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Chris Lattnere6794492002-08-12 21:17:25 +00001//===- InstructionCombining.cpp - Combine multiple instructions -----------===//
Misha Brukmanb1c93172005-04-21 23:48:37 +00002//
John Criswell482202a2003-10-20 19:43:21 +00003// The LLVM Compiler Infrastructure
4//
5// This file was developed by the LLVM research group and is distributed under
6// the University of Illinois Open Source License. See LICENSE.TXT for details.
Misha Brukmanb1c93172005-04-21 23:48:37 +00007//
John Criswell482202a2003-10-20 19:43:21 +00008//===----------------------------------------------------------------------===//
Chris Lattnerca081252001-12-14 16:52:21 +00009//
10// InstructionCombining - Combine instructions to form fewer, simple
Chris Lattner99f48c62002-09-02 04:59:56 +000011// instructions. This pass does not modify the CFG This pass is where algebraic
12// simplification happens.
Chris Lattnerca081252001-12-14 16:52:21 +000013//
14// This pass combines things like:
Chris Lattner07418422007-03-18 22:51:34 +000015// %Y = add i32 %X, 1
16// %Z = add i32 %Y, 1
Chris Lattnerca081252001-12-14 16:52:21 +000017// into:
Chris Lattner07418422007-03-18 22:51:34 +000018// %Z = add i32 %X, 2
Chris Lattnerca081252001-12-14 16:52:21 +000019//
20// This is a simple worklist driven algorithm.
21//
Chris Lattner216c7b82003-09-10 05:29:43 +000022// This pass guarantees that the following canonicalizations are performed on
Chris Lattnerbfb1d032003-07-23 21:41:57 +000023// the program:
24// 1. If a binary operator has a constant operand, it is moved to the RHS
Chris Lattnerdeaa0dd2003-08-12 21:53:41 +000025// 2. Bitwise operators with constant operands are always grouped so that
26// shifts are performed first, then or's, then and's, then xor's.
Reid Spencer266e42b2006-12-23 06:05:41 +000027// 3. Compare instructions are converted from <,>,<=,>= to ==,!= if possible
28// 4. All cmp instructions on boolean values are replaced with logical ops
Chris Lattnerede3fe02003-08-13 04:18:28 +000029// 5. add X, X is represented as (X*2) => (X << 1)
30// 6. Multiplies with a power-of-two constant argument are transformed into
31// shifts.
Chris Lattner7515cab2004-11-14 19:13:23 +000032// ... etc.
Chris Lattnerbfb1d032003-07-23 21:41:57 +000033//
Chris Lattnerca081252001-12-14 16:52:21 +000034//===----------------------------------------------------------------------===//
35
Chris Lattner7d2a5392004-03-13 23:54:27 +000036#define DEBUG_TYPE "instcombine"
Chris Lattnerb4cfa7f2002-05-07 20:03:00 +000037#include "llvm/Transforms/Scalar.h"
Chris Lattner00648e12004-10-12 04:52:52 +000038#include "llvm/IntrinsicInst.h"
Chris Lattner04805fa2002-02-26 21:46:54 +000039#include "llvm/Pass.h"
Chris Lattner1085bdf2002-11-04 16:18:53 +000040#include "llvm/DerivedTypes.h"
Chris Lattner0f1d8a32003-06-26 05:06:25 +000041#include "llvm/GlobalVariable.h"
Chris Lattner024f4ab2007-01-30 23:46:24 +000042#include "llvm/Analysis/ConstantFolding.h"
Chris Lattnerf4ad1652003-11-02 05:57:39 +000043#include "llvm/Target/TargetData.h"
44#include "llvm/Transforms/Utils/BasicBlockUtils.h"
45#include "llvm/Transforms/Utils/Local.h"
Chris Lattner69193f92004-04-05 01:30:19 +000046#include "llvm/Support/CallSite.h"
Chris Lattner39c98bb2004-12-08 23:43:58 +000047#include "llvm/Support/Debug.h"
Chris Lattner69193f92004-04-05 01:30:19 +000048#include "llvm/Support/GetElementPtrTypeIterator.h"
Chris Lattner260ab202002-04-18 17:39:14 +000049#include "llvm/Support/InstVisitor.h"
Chris Lattner22d00a82005-08-02 19:16:58 +000050#include "llvm/Support/MathExtras.h"
Chris Lattnerd4252a72004-07-30 07:50:03 +000051#include "llvm/Support/PatternMatch.h"
Chris Lattner3d27be12006-08-27 12:54:02 +000052#include "llvm/Support/Compiler.h"
Chris Lattnerb15e2b12007-03-02 21:28:56 +000053#include "llvm/ADT/DenseMap.h"
Chris Lattnerf96f4a82007-01-31 04:40:53 +000054#include "llvm/ADT/SmallVector.h"
Chris Lattner7907e5f2007-02-15 19:41:52 +000055#include "llvm/ADT/SmallPtrSet.h"
Reid Spencer7c16caa2004-09-01 22:55:40 +000056#include "llvm/ADT/Statistic.h"
Chris Lattner39c98bb2004-12-08 23:43:58 +000057#include "llvm/ADT/STLExtras.h"
Chris Lattner053c0932002-05-14 15:24:07 +000058#include <algorithm>
Reid Spencer3f4e6e82007-02-04 00:40:42 +000059#include <set>
Chris Lattner8427bff2003-12-07 01:24:23 +000060using namespace llvm;
Chris Lattnerd4252a72004-07-30 07:50:03 +000061using namespace llvm::PatternMatch;
Brian Gaeke960707c2003-11-11 22:41:34 +000062
Chris Lattner79a42ac2006-12-19 21:40:18 +000063STATISTIC(NumCombined , "Number of insts combined");
64STATISTIC(NumConstProp, "Number of constant folds");
65STATISTIC(NumDeadInst , "Number of dead inst eliminated");
66STATISTIC(NumDeadStore, "Number of dead stores eliminated");
67STATISTIC(NumSunkInst , "Number of instructions sunk");
Chris Lattnerbf3a0992002-10-01 22:38:41 +000068
Chris Lattner79a42ac2006-12-19 21:40:18 +000069namespace {
Chris Lattner4a4c7fe2006-06-28 22:08:15 +000070 class VISIBILITY_HIDDEN InstCombiner
71 : public FunctionPass,
72 public InstVisitor<InstCombiner, Instruction*> {
Chris Lattner260ab202002-04-18 17:39:14 +000073 // Worklist of all of the instructions that need to be simplified.
Chris Lattnerb15e2b12007-03-02 21:28:56 +000074 std::vector<Instruction*> Worklist;
75 DenseMap<Instruction*, unsigned> WorklistMap;
Chris Lattnerf4ad1652003-11-02 05:57:39 +000076 TargetData *TD;
Chris Lattner8258b442007-03-04 04:27:24 +000077 bool MustPreserveLCSSA;
Chris Lattnerb15e2b12007-03-02 21:28:56 +000078 public:
79 /// AddToWorkList - Add the specified instruction to the worklist if it
80 /// isn't already in it.
81 void AddToWorkList(Instruction *I) {
82 if (WorklistMap.insert(std::make_pair(I, Worklist.size())))
83 Worklist.push_back(I);
84 }
85
86 // RemoveFromWorkList - remove I from the worklist if it exists.
87 void RemoveFromWorkList(Instruction *I) {
88 DenseMap<Instruction*, unsigned>::iterator It = WorklistMap.find(I);
89 if (It == WorklistMap.end()) return; // Not in worklist.
90
91 // Don't bother moving everything down, just null out the slot.
92 Worklist[It->second] = 0;
93
94 WorklistMap.erase(It);
95 }
96
97 Instruction *RemoveOneFromWorkList() {
98 Instruction *I = Worklist.back();
99 Worklist.pop_back();
100 WorklistMap.erase(I);
101 return I;
102 }
Chris Lattner260ab202002-04-18 17:39:14 +0000103
Chris Lattnerb15e2b12007-03-02 21:28:56 +0000104
Chris Lattner51ea1272004-02-28 05:22:00 +0000105 /// AddUsersToWorkList - When an instruction is simplified, add all users of
106 /// the instruction to the work lists because they might get more simplified
107 /// now.
108 ///
Chris Lattner2590e512006-02-07 06:56:34 +0000109 void AddUsersToWorkList(Value &I) {
Chris Lattner113f4f42002-06-25 16:13:24 +0000110 for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
Chris Lattner260ab202002-04-18 17:39:14 +0000111 UI != UE; ++UI)
Chris Lattnerb15e2b12007-03-02 21:28:56 +0000112 AddToWorkList(cast<Instruction>(*UI));
Chris Lattner260ab202002-04-18 17:39:14 +0000113 }
114
Chris Lattner51ea1272004-02-28 05:22:00 +0000115 /// AddUsesToWorkList - When an instruction is simplified, add operands to
116 /// the work lists because they might get more simplified now.
117 ///
118 void AddUsesToWorkList(Instruction &I) {
119 for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
120 if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i)))
Chris Lattnerb15e2b12007-03-02 21:28:56 +0000121 AddToWorkList(Op);
Chris Lattner51ea1272004-02-28 05:22:00 +0000122 }
Chris Lattner2deeaea2006-10-05 06:55:50 +0000123
124 /// AddSoonDeadInstToWorklist - The specified instruction is about to become
125 /// dead. Add all of its operands to the worklist, turning them into
126 /// undef's to reduce the number of uses of those instructions.
127 ///
128 /// Return the specified operand before it is turned into an undef.
129 ///
130 Value *AddSoonDeadInstToWorklist(Instruction &I, unsigned op) {
131 Value *R = I.getOperand(op);
132
133 for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
134 if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i))) {
Chris Lattnerb15e2b12007-03-02 21:28:56 +0000135 AddToWorkList(Op);
Chris Lattner2deeaea2006-10-05 06:55:50 +0000136 // Set the operand to undef to drop the use.
137 I.setOperand(i, UndefValue::get(Op->getType()));
138 }
139
140 return R;
141 }
Chris Lattner51ea1272004-02-28 05:22:00 +0000142
Chris Lattner260ab202002-04-18 17:39:14 +0000143 public:
Chris Lattner113f4f42002-06-25 16:13:24 +0000144 virtual bool runOnFunction(Function &F);
Chris Lattner960a5432007-03-03 02:04:50 +0000145
146 bool DoOneIteration(Function &F, unsigned ItNum);
Chris Lattner260ab202002-04-18 17:39:14 +0000147
Chris Lattnerf12cc842002-04-28 21:27:06 +0000148 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
Chris Lattnerf4ad1652003-11-02 05:57:39 +0000149 AU.addRequired<TargetData>();
Owen Andersona6968f82006-07-10 19:03:49 +0000150 AU.addPreservedID(LCSSAID);
Chris Lattner820d9712002-10-21 20:00:28 +0000151 AU.setPreservesCFG();
Chris Lattnerf12cc842002-04-28 21:27:06 +0000152 }
153
Chris Lattner69193f92004-04-05 01:30:19 +0000154 TargetData &getTargetData() const { return *TD; }
155
Chris Lattner260ab202002-04-18 17:39:14 +0000156 // Visitation implementation - Implement instruction combining for different
157 // instruction types. The semantics are as follows:
158 // Return Value:
159 // null - No change was made
Chris Lattnere6794492002-08-12 21:17:25 +0000160 // I - Change was made, I is still valid, I may be dead though
Chris Lattner260ab202002-04-18 17:39:14 +0000161 // otherwise - Change was made, replace I with returned instruction
Misha Brukmanb1c93172005-04-21 23:48:37 +0000162 //
Chris Lattner113f4f42002-06-25 16:13:24 +0000163 Instruction *visitAdd(BinaryOperator &I);
164 Instruction *visitSub(BinaryOperator &I);
165 Instruction *visitMul(BinaryOperator &I);
Reid Spencer7eb55b32006-11-02 01:53:59 +0000166 Instruction *visitURem(BinaryOperator &I);
167 Instruction *visitSRem(BinaryOperator &I);
168 Instruction *visitFRem(BinaryOperator &I);
169 Instruction *commonRemTransforms(BinaryOperator &I);
170 Instruction *commonIRemTransforms(BinaryOperator &I);
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000171 Instruction *commonDivTransforms(BinaryOperator &I);
172 Instruction *commonIDivTransforms(BinaryOperator &I);
173 Instruction *visitUDiv(BinaryOperator &I);
174 Instruction *visitSDiv(BinaryOperator &I);
175 Instruction *visitFDiv(BinaryOperator &I);
Chris Lattner113f4f42002-06-25 16:13:24 +0000176 Instruction *visitAnd(BinaryOperator &I);
177 Instruction *visitOr (BinaryOperator &I);
178 Instruction *visitXor(BinaryOperator &I);
Reid Spencer2341c222007-02-02 02:16:23 +0000179 Instruction *visitShl(BinaryOperator &I);
180 Instruction *visitAShr(BinaryOperator &I);
181 Instruction *visitLShr(BinaryOperator &I);
182 Instruction *commonShiftTransforms(BinaryOperator &I);
Reid Spencer266e42b2006-12-23 06:05:41 +0000183 Instruction *visitFCmpInst(FCmpInst &I);
184 Instruction *visitICmpInst(ICmpInst &I);
185 Instruction *visitICmpInstWithCastAndCast(ICmpInst &ICI);
Chris Lattnerd1f46d32005-04-24 06:59:08 +0000186
Reid Spencer266e42b2006-12-23 06:05:41 +0000187 Instruction *FoldGEPICmp(User *GEPLHS, Value *RHS,
188 ICmpInst::Predicate Cond, Instruction &I);
Reid Spencere0fc4df2006-10-20 07:07:24 +0000189 Instruction *FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
Reid Spencer2341c222007-02-02 02:16:23 +0000190 BinaryOperator &I);
Reid Spencer6c38f0b2006-11-27 01:05:10 +0000191 Instruction *commonCastTransforms(CastInst &CI);
192 Instruction *commonIntCastTransforms(CastInst &CI);
193 Instruction *visitTrunc(CastInst &CI);
194 Instruction *visitZExt(CastInst &CI);
195 Instruction *visitSExt(CastInst &CI);
196 Instruction *visitFPTrunc(CastInst &CI);
197 Instruction *visitFPExt(CastInst &CI);
198 Instruction *visitFPToUI(CastInst &CI);
199 Instruction *visitFPToSI(CastInst &CI);
200 Instruction *visitUIToFP(CastInst &CI);
201 Instruction *visitSIToFP(CastInst &CI);
202 Instruction *visitPtrToInt(CastInst &CI);
203 Instruction *visitIntToPtr(CastInst &CI);
204 Instruction *visitBitCast(CastInst &CI);
Chris Lattner411336f2005-01-19 21:50:18 +0000205 Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
206 Instruction *FI);
Chris Lattnerb909e8b2004-03-12 05:52:32 +0000207 Instruction *visitSelectInst(SelectInst &CI);
Chris Lattner970c33a2003-06-19 17:00:31 +0000208 Instruction *visitCallInst(CallInst &CI);
209 Instruction *visitInvokeInst(InvokeInst &II);
Chris Lattner113f4f42002-06-25 16:13:24 +0000210 Instruction *visitPHINode(PHINode &PN);
211 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
Chris Lattner1085bdf2002-11-04 16:18:53 +0000212 Instruction *visitAllocationInst(AllocationInst &AI);
Chris Lattner8427bff2003-12-07 01:24:23 +0000213 Instruction *visitFreeInst(FreeInst &FI);
Chris Lattner0f1d8a32003-06-26 05:06:25 +0000214 Instruction *visitLoadInst(LoadInst &LI);
Chris Lattner31f486c2005-01-31 05:36:43 +0000215 Instruction *visitStoreInst(StoreInst &SI);
Chris Lattner9eef8a72003-06-04 04:46:00 +0000216 Instruction *visitBranchInst(BranchInst &BI);
Chris Lattner4c9c20a2004-07-03 00:26:11 +0000217 Instruction *visitSwitchInst(SwitchInst &SI);
Chris Lattner39fac442006-04-15 01:39:45 +0000218 Instruction *visitInsertElementInst(InsertElementInst &IE);
Robert Bocchinoa8352962006-01-13 22:48:06 +0000219 Instruction *visitExtractElementInst(ExtractElementInst &EI);
Chris Lattnerfbb77a42006-04-10 22:45:52 +0000220 Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI);
Chris Lattner260ab202002-04-18 17:39:14 +0000221
222 // visitInstruction - Specify what to return for unhandled instructions...
Chris Lattner113f4f42002-06-25 16:13:24 +0000223 Instruction *visitInstruction(Instruction &I) { return 0; }
Chris Lattner6d14f2a2002-08-09 23:47:40 +0000224
Chris Lattner970c33a2003-06-19 17:00:31 +0000225 private:
Chris Lattneraec3d942003-10-07 22:32:43 +0000226 Instruction *visitCallSite(CallSite CS);
Chris Lattner970c33a2003-06-19 17:00:31 +0000227 bool transformConstExprCastCall(CallSite CS);
228
Chris Lattner69193f92004-04-05 01:30:19 +0000229 public:
Chris Lattner6d14f2a2002-08-09 23:47:40 +0000230 // InsertNewInstBefore - insert an instruction New before instruction Old
231 // in the program. Add the new instruction to the worklist.
232 //
Chris Lattner623826c2004-09-28 21:48:02 +0000233 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
Chris Lattner65217ff2002-08-23 18:32:43 +0000234 assert(New && New->getParent() == 0 &&
235 "New instruction already inserted into a basic block!");
Chris Lattner6d14f2a2002-08-09 23:47:40 +0000236 BasicBlock *BB = Old.getParent();
237 BB->getInstList().insert(&Old, New); // Insert inst
Chris Lattnerb15e2b12007-03-02 21:28:56 +0000238 AddToWorkList(New);
Chris Lattnere79e8542004-02-23 06:38:22 +0000239 return New;
Chris Lattner6d14f2a2002-08-09 23:47:40 +0000240 }
241
Chris Lattner7e794272004-09-24 15:21:34 +0000242 /// InsertCastBefore - Insert a cast of V to TY before the instruction POS.
243 /// This also adds the cast to the worklist. Finally, this returns the
244 /// cast.
Reid Spencer13bc5d72006-12-12 09:18:51 +0000245 Value *InsertCastBefore(Instruction::CastOps opc, Value *V, const Type *Ty,
246 Instruction &Pos) {
Chris Lattner7e794272004-09-24 15:21:34 +0000247 if (V->getType() == Ty) return V;
Misha Brukmanb1c93172005-04-21 23:48:37 +0000248
Chris Lattnere79d2492006-04-06 19:19:17 +0000249 if (Constant *CV = dyn_cast<Constant>(V))
Reid Spencer13bc5d72006-12-12 09:18:51 +0000250 return ConstantExpr::getCast(opc, CV, Ty);
Chris Lattnere79d2492006-04-06 19:19:17 +0000251
Reid Spencer13bc5d72006-12-12 09:18:51 +0000252 Instruction *C = CastInst::create(opc, V, Ty, V->getName(), &Pos);
Chris Lattnerb15e2b12007-03-02 21:28:56 +0000253 AddToWorkList(C);
Chris Lattner7e794272004-09-24 15:21:34 +0000254 return C;
255 }
256
Chris Lattner6d14f2a2002-08-09 23:47:40 +0000257 // ReplaceInstUsesWith - This method is to be used when an instruction is
258 // found to be dead, replacable with another preexisting expression. Here
259 // we add all uses of I to the worklist, replace all uses of I with the new
260 // value, then return I, so that the inst combiner will know that I was
261 // modified.
262 //
263 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
Chris Lattner51ea1272004-02-28 05:22:00 +0000264 AddUsersToWorkList(I); // Add all modified instrs to worklist
Chris Lattner8953b902004-04-05 02:10:19 +0000265 if (&I != V) {
266 I.replaceAllUsesWith(V);
267 return &I;
268 } else {
269 // If we are replacing the instruction with itself, this must be in a
270 // segment of unreachable code, so just clobber the instruction.
Chris Lattner8ba9ec92004-10-18 02:59:09 +0000271 I.replaceAllUsesWith(UndefValue::get(I.getType()));
Chris Lattner8953b902004-04-05 02:10:19 +0000272 return &I;
273 }
Chris Lattner6d14f2a2002-08-09 23:47:40 +0000274 }
Chris Lattner51ea1272004-02-28 05:22:00 +0000275
Chris Lattner2590e512006-02-07 06:56:34 +0000276 // UpdateValueUsesWith - This method is to be used when an value is
277 // found to be replacable with another preexisting expression or was
278 // updated. Here we add all uses of I to the worklist, replace all uses of
279 // I with the new value (unless the instruction was just updated), then
280 // return true, so that the inst combiner will know that I was modified.
281 //
282 bool UpdateValueUsesWith(Value *Old, Value *New) {
283 AddUsersToWorkList(*Old); // Add all modified instrs to worklist
284 if (Old != New)
285 Old->replaceAllUsesWith(New);
286 if (Instruction *I = dyn_cast<Instruction>(Old))
Chris Lattnerb15e2b12007-03-02 21:28:56 +0000287 AddToWorkList(I);
Chris Lattner5b2edb12006-02-12 08:02:11 +0000288 if (Instruction *I = dyn_cast<Instruction>(New))
Chris Lattnerb15e2b12007-03-02 21:28:56 +0000289 AddToWorkList(I);
Chris Lattner2590e512006-02-07 06:56:34 +0000290 return true;
291 }
292
Chris Lattner51ea1272004-02-28 05:22:00 +0000293 // EraseInstFromFunction - When dealing with an instruction that has side
294 // effects or produces a void value, we can't rely on DCE to delete the
295 // instruction. Instead, visit methods should return the value returned by
296 // this function.
297 Instruction *EraseInstFromFunction(Instruction &I) {
298 assert(I.use_empty() && "Cannot erase instruction that is used!");
299 AddUsesToWorkList(I);
Chris Lattnerb15e2b12007-03-02 21:28:56 +0000300 RemoveFromWorkList(&I);
Chris Lattner95307542004-11-18 21:41:39 +0000301 I.eraseFromParent();
Chris Lattner51ea1272004-02-28 05:22:00 +0000302 return 0; // Don't do anything with FI
303 }
304
Chris Lattner3ac7c262003-08-13 20:16:26 +0000305 private:
Chris Lattnerdfae8be2003-07-24 17:35:25 +0000306 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
307 /// InsertBefore instruction. This is specialized a bit to avoid inserting
308 /// casts that are known to not do anything...
309 ///
Reid Spencer13bc5d72006-12-12 09:18:51 +0000310 Value *InsertOperandCastBefore(Instruction::CastOps opcode,
311 Value *V, const Type *DestTy,
Chris Lattnerdfae8be2003-07-24 17:35:25 +0000312 Instruction *InsertBefore);
313
Reid Spencer266e42b2006-12-23 06:05:41 +0000314 /// SimplifyCommutative - This performs a few simplifications for
315 /// commutative operators.
Chris Lattner7fb29e12003-03-11 00:12:48 +0000316 bool SimplifyCommutative(BinaryOperator &I);
Chris Lattnerba1cb382003-09-19 17:17:26 +0000317
Reid Spencer266e42b2006-12-23 06:05:41 +0000318 /// SimplifyCompare - This reorders the operands of a CmpInst to get them in
319 /// most-complex to least-complex order.
320 bool SimplifyCompare(CmpInst &I);
321
Reid Spencer1791f232007-03-12 17:25:59 +0000322 bool SimplifyDemandedBits(Value *V, uint64_t DemandedMask,
Chris Lattner0157e7f2006-02-11 09:31:47 +0000323 uint64_t &KnownZero, uint64_t &KnownOne,
324 unsigned Depth = 0);
Chris Lattner6a4adcd2004-09-29 05:07:12 +0000325
Reid Spencer1791f232007-03-12 17:25:59 +0000326 bool SimplifyDemandedBits(Value *V, APInt DemandedMask,
327 APInt& KnownZero, APInt& KnownOne,
328 unsigned Depth = 0);
329
Chris Lattner2deeaea2006-10-05 06:55:50 +0000330 Value *SimplifyDemandedVectorElts(Value *V, uint64_t DemandedElts,
331 uint64_t &UndefElts, unsigned Depth = 0);
332
Chris Lattner6a4adcd2004-09-29 05:07:12 +0000333 // FoldOpIntoPhi - Given a binary operator or cast instruction which has a
334 // PHI node as operand #0, see if we can fold the instruction into the PHI
335 // (which is only possible if all operands to the PHI are constants).
336 Instruction *FoldOpIntoPhi(Instruction &I);
337
Chris Lattner7515cab2004-11-14 19:13:23 +0000338 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
339 // operator and they all are only used by the PHI, PHI together their
340 // inputs, and do the operation once, to the result of the PHI.
341 Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
Chris Lattnercadac0c2006-11-01 04:51:18 +0000342 Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN);
343
344
Zhou Sheng75b871f2007-01-11 12:24:14 +0000345 Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS,
346 ConstantInt *AndRHS, BinaryOperator &TheAnd);
Chris Lattneraf517572005-09-18 04:24:45 +0000347
Zhou Sheng75b871f2007-01-11 12:24:14 +0000348 Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask,
Chris Lattneraf517572005-09-18 04:24:45 +0000349 bool isSub, Instruction &I);
Chris Lattner6862fbd2004-09-29 17:40:11 +0000350 Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
Reid Spencer266e42b2006-12-23 06:05:41 +0000351 bool isSigned, bool Inside, Instruction &IB);
Chris Lattner216be912005-10-24 06:03:58 +0000352 Instruction *PromoteCastOfAllocation(CastInst &CI, AllocationInst &AI);
Chris Lattnerc482a9e2006-06-15 19:07:26 +0000353 Instruction *MatchBSwap(BinaryOperator &I);
354
Reid Spencer74a528b2006-12-13 18:21:21 +0000355 Value *EvaluateInDifferentType(Value *V, const Type *Ty, bool isSigned);
Chris Lattner260ab202002-04-18 17:39:14 +0000356 };
Chris Lattnerb28b6802002-07-23 18:06:35 +0000357
Chris Lattnerc2d3d312006-08-27 22:42:52 +0000358 RegisterPass<InstCombiner> X("instcombine", "Combine redundant instructions");
Chris Lattner260ab202002-04-18 17:39:14 +0000359}
360
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000361// getComplexity: Assign a complexity or rank value to LLVM Values...
Chris Lattner81a7a232004-10-16 18:11:37 +0000362// 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000363static unsigned getComplexity(Value *V) {
364 if (isa<Instruction>(V)) {
365 if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V))
Chris Lattner81a7a232004-10-16 18:11:37 +0000366 return 3;
367 return 4;
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000368 }
Chris Lattner81a7a232004-10-16 18:11:37 +0000369 if (isa<Argument>(V)) return 3;
370 return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000371}
Chris Lattner260ab202002-04-18 17:39:14 +0000372
Chris Lattner7fb29e12003-03-11 00:12:48 +0000373// isOnlyUse - Return true if this instruction will be deleted if we stop using
374// it.
375static bool isOnlyUse(Value *V) {
Chris Lattnerf95d9b92003-10-15 16:48:29 +0000376 return V->hasOneUse() || isa<Constant>(V);
Chris Lattner7fb29e12003-03-11 00:12:48 +0000377}
378
Chris Lattnere79e8542004-02-23 06:38:22 +0000379// getPromotedType - Return the specified type promoted as it would be to pass
380// though a va_arg area...
381static const Type *getPromotedType(const Type *Ty) {
Reid Spencer7a9c62b2007-01-12 07:05:14 +0000382 if (const IntegerType* ITy = dyn_cast<IntegerType>(Ty)) {
383 if (ITy->getBitWidth() < 32)
384 return Type::Int32Ty;
385 } else if (Ty == Type::FloatTy)
386 return Type::DoubleTy;
387 return Ty;
Chris Lattnere79e8542004-02-23 06:38:22 +0000388}
389
Reid Spencer6c38f0b2006-11-27 01:05:10 +0000390/// getBitCastOperand - If the specified operand is a CastInst or a constant
391/// expression bitcast, return the operand value, otherwise return null.
392static Value *getBitCastOperand(Value *V) {
393 if (BitCastInst *I = dyn_cast<BitCastInst>(V))
Chris Lattner567b81f2005-09-13 00:40:14 +0000394 return I->getOperand(0);
395 else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
Reid Spencer6c38f0b2006-11-27 01:05:10 +0000396 if (CE->getOpcode() == Instruction::BitCast)
Chris Lattner567b81f2005-09-13 00:40:14 +0000397 return CE->getOperand(0);
398 return 0;
399}
400
Reid Spencer6c38f0b2006-11-27 01:05:10 +0000401/// This function is a wrapper around CastInst::isEliminableCastPair. It
402/// simply extracts arguments and returns what that function returns.
Reid Spencer6c38f0b2006-11-27 01:05:10 +0000403static Instruction::CastOps
404isEliminableCastPair(
405 const CastInst *CI, ///< The first cast instruction
406 unsigned opcode, ///< The opcode of the second cast instruction
407 const Type *DstTy, ///< The target type for the second cast instruction
408 TargetData *TD ///< The target data for pointer size
409) {
410
411 const Type *SrcTy = CI->getOperand(0)->getType(); // A from above
412 const Type *MidTy = CI->getType(); // B from above
Chris Lattner1d441ad2006-05-06 09:00:16 +0000413
Reid Spencer6c38f0b2006-11-27 01:05:10 +0000414 // Get the opcodes of the two Cast instructions
415 Instruction::CastOps firstOp = Instruction::CastOps(CI->getOpcode());
416 Instruction::CastOps secondOp = Instruction::CastOps(opcode);
Chris Lattner1d441ad2006-05-06 09:00:16 +0000417
Reid Spencer6c38f0b2006-11-27 01:05:10 +0000418 return Instruction::CastOps(
419 CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy,
420 DstTy, TD->getIntPtrType()));
Chris Lattner1d441ad2006-05-06 09:00:16 +0000421}
422
423/// ValueRequiresCast - Return true if the cast from "V to Ty" actually results
424/// in any code being generated. It does not require codegen if V is simple
425/// enough or if the cast can be folded into other casts.
Reid Spencer266e42b2006-12-23 06:05:41 +0000426static bool ValueRequiresCast(Instruction::CastOps opcode, const Value *V,
427 const Type *Ty, TargetData *TD) {
Chris Lattner1d441ad2006-05-06 09:00:16 +0000428 if (V->getType() == Ty || isa<Constant>(V)) return false;
429
Chris Lattner99155be2006-05-25 23:24:33 +0000430 // If this is another cast that can be eliminated, it isn't codegen either.
Chris Lattner1d441ad2006-05-06 09:00:16 +0000431 if (const CastInst *CI = dyn_cast<CastInst>(V))
Reid Spencer266e42b2006-12-23 06:05:41 +0000432 if (isEliminableCastPair(CI, opcode, Ty, TD))
Chris Lattner1d441ad2006-05-06 09:00:16 +0000433 return false;
434 return true;
435}
436
437/// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
438/// InsertBefore instruction. This is specialized a bit to avoid inserting
439/// casts that are known to not do anything...
440///
Reid Spencer13bc5d72006-12-12 09:18:51 +0000441Value *InstCombiner::InsertOperandCastBefore(Instruction::CastOps opcode,
442 Value *V, const Type *DestTy,
Chris Lattner1d441ad2006-05-06 09:00:16 +0000443 Instruction *InsertBefore) {
444 if (V->getType() == DestTy) return V;
445 if (Constant *C = dyn_cast<Constant>(V))
Reid Spencer13bc5d72006-12-12 09:18:51 +0000446 return ConstantExpr::getCast(opcode, C, DestTy);
Chris Lattner1d441ad2006-05-06 09:00:16 +0000447
Reid Spencer13bc5d72006-12-12 09:18:51 +0000448 return InsertCastBefore(opcode, V, DestTy, *InsertBefore);
Chris Lattner1d441ad2006-05-06 09:00:16 +0000449}
450
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000451// SimplifyCommutative - This performs a few simplifications for commutative
452// operators:
Chris Lattner260ab202002-04-18 17:39:14 +0000453//
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000454// 1. Order operands such that they are listed from right (least complex) to
455// left (most complex). This puts constants before unary operators before
456// binary operators.
457//
Chris Lattner7fb29e12003-03-11 00:12:48 +0000458// 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
459// 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000460//
Chris Lattner7fb29e12003-03-11 00:12:48 +0000461bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000462 bool Changed = false;
463 if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
464 Changed = !I.swapOperands();
Misha Brukmanb1c93172005-04-21 23:48:37 +0000465
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000466 if (!I.isAssociative()) return Changed;
467 Instruction::BinaryOps Opcode = I.getOpcode();
Chris Lattner7fb29e12003-03-11 00:12:48 +0000468 if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
469 if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
470 if (isa<Constant>(I.getOperand(1))) {
Chris Lattner34428442003-05-27 16:40:51 +0000471 Constant *Folded = ConstantExpr::get(I.getOpcode(),
472 cast<Constant>(I.getOperand(1)),
473 cast<Constant>(Op->getOperand(1)));
Chris Lattner7fb29e12003-03-11 00:12:48 +0000474 I.setOperand(0, Op->getOperand(0));
475 I.setOperand(1, Folded);
476 return true;
477 } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
478 if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
479 isOnlyUse(Op) && isOnlyUse(Op1)) {
480 Constant *C1 = cast<Constant>(Op->getOperand(1));
481 Constant *C2 = cast<Constant>(Op1->getOperand(1));
482
483 // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
Chris Lattner34428442003-05-27 16:40:51 +0000484 Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
Chris Lattner7fb29e12003-03-11 00:12:48 +0000485 Instruction *New = BinaryOperator::create(Opcode, Op->getOperand(0),
486 Op1->getOperand(0),
487 Op1->getName(), &I);
Chris Lattnerb15e2b12007-03-02 21:28:56 +0000488 AddToWorkList(New);
Chris Lattner7fb29e12003-03-11 00:12:48 +0000489 I.setOperand(0, New);
490 I.setOperand(1, Folded);
491 return true;
Misha Brukmanb1c93172005-04-21 23:48:37 +0000492 }
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000493 }
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000494 return Changed;
Chris Lattner260ab202002-04-18 17:39:14 +0000495}
Chris Lattnerca081252001-12-14 16:52:21 +0000496
Reid Spencer266e42b2006-12-23 06:05:41 +0000497/// SimplifyCompare - For a CmpInst this function just orders the operands
498/// so that theyare listed from right (least complex) to left (most complex).
499/// This puts constants before unary operators before binary operators.
500bool InstCombiner::SimplifyCompare(CmpInst &I) {
501 if (getComplexity(I.getOperand(0)) >= getComplexity(I.getOperand(1)))
502 return false;
503 I.swapOperands();
504 // Compare instructions are not associative so there's nothing else we can do.
505 return true;
506}
507
Chris Lattnerbb74e222003-03-10 23:06:50 +0000508// dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
509// if the LHS is a constant zero (which is the 'negate' form).
Chris Lattner9fa53de2002-05-06 16:49:18 +0000510//
Chris Lattnerbb74e222003-03-10 23:06:50 +0000511static inline Value *dyn_castNegVal(Value *V) {
512 if (BinaryOperator::isNeg(V))
Chris Lattnerd6f636a2005-04-24 07:30:14 +0000513 return BinaryOperator::getNegArgument(V);
Chris Lattnerbb74e222003-03-10 23:06:50 +0000514
Chris Lattner9ad0d552004-12-14 20:08:06 +0000515 // Constants can be considered to be negated values if they can be folded.
516 if (ConstantInt *C = dyn_cast<ConstantInt>(V))
517 return ConstantExpr::getNeg(C);
Chris Lattnerbb74e222003-03-10 23:06:50 +0000518 return 0;
Chris Lattner9fa53de2002-05-06 16:49:18 +0000519}
520
Chris Lattnerbb74e222003-03-10 23:06:50 +0000521static inline Value *dyn_castNotVal(Value *V) {
522 if (BinaryOperator::isNot(V))
Chris Lattnerd6f636a2005-04-24 07:30:14 +0000523 return BinaryOperator::getNotArgument(V);
Chris Lattnerbb74e222003-03-10 23:06:50 +0000524
525 // Constants can be considered to be not'ed values...
Zhou Sheng75b871f2007-01-11 12:24:14 +0000526 if (ConstantInt *C = dyn_cast<ConstantInt>(V))
Chris Lattnerc8e7e292004-06-10 02:12:35 +0000527 return ConstantExpr::getNot(C);
Chris Lattnerbb74e222003-03-10 23:06:50 +0000528 return 0;
529}
530
Chris Lattner7fb29e12003-03-11 00:12:48 +0000531// dyn_castFoldableMul - If this value is a multiply that can be folded into
532// other computations (because it has a constant operand), return the
Chris Lattner8c3e7b92004-11-13 19:50:12 +0000533// non-constant operand of the multiply, and set CST to point to the multiplier.
534// Otherwise, return null.
Chris Lattner7fb29e12003-03-11 00:12:48 +0000535//
Chris Lattner8c3e7b92004-11-13 19:50:12 +0000536static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
Chris Lattner03c49532007-01-15 02:27:26 +0000537 if (V->hasOneUse() && V->getType()->isInteger())
Chris Lattner8c3e7b92004-11-13 19:50:12 +0000538 if (Instruction *I = dyn_cast<Instruction>(V)) {
Chris Lattner7fb29e12003-03-11 00:12:48 +0000539 if (I->getOpcode() == Instruction::Mul)
Chris Lattner970136362004-11-15 05:54:07 +0000540 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
Chris Lattner7fb29e12003-03-11 00:12:48 +0000541 return I->getOperand(0);
Chris Lattner8c3e7b92004-11-13 19:50:12 +0000542 if (I->getOpcode() == Instruction::Shl)
Chris Lattner970136362004-11-15 05:54:07 +0000543 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
Chris Lattner8c3e7b92004-11-13 19:50:12 +0000544 // The multiplier is really 1 << CST.
545 Constant *One = ConstantInt::get(V->getType(), 1);
546 CST = cast<ConstantInt>(ConstantExpr::getShl(One, CST));
547 return I->getOperand(0);
548 }
549 }
Chris Lattner7fb29e12003-03-11 00:12:48 +0000550 return 0;
Chris Lattner3082c5a2003-02-18 19:28:33 +0000551}
Chris Lattner31ae8632002-08-14 17:51:49 +0000552
Chris Lattner0798af32005-01-13 20:14:25 +0000553/// dyn_castGetElementPtr - If this is a getelementptr instruction or constant
554/// expression, return it.
555static User *dyn_castGetElementPtr(Value *V) {
556 if (isa<GetElementPtrInst>(V)) return cast<User>(V);
557 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
558 if (CE->getOpcode() == Instruction::GetElementPtr)
559 return cast<User>(V);
560 return false;
561}
562
Chris Lattner623826c2004-09-28 21:48:02 +0000563// AddOne, SubOne - Add or subtract a constant one from an integer constant...
Chris Lattner6862fbd2004-09-29 17:40:11 +0000564static ConstantInt *AddOne(ConstantInt *C) {
565 return cast<ConstantInt>(ConstantExpr::getAdd(C,
566 ConstantInt::get(C->getType(), 1)));
Chris Lattner623826c2004-09-28 21:48:02 +0000567}
Chris Lattner6862fbd2004-09-29 17:40:11 +0000568static ConstantInt *SubOne(ConstantInt *C) {
569 return cast<ConstantInt>(ConstantExpr::getSub(C,
570 ConstantInt::get(C->getType(), 1)));
Chris Lattner623826c2004-09-28 21:48:02 +0000571}
572
Chris Lattner4534dd592006-02-09 07:38:58 +0000573/// ComputeMaskedBits - Determine which of the bits specified in Mask are
574/// known to be either zero or one and return them in the KnownZero/KnownOne
Reid Spenceraa696402007-03-08 01:46:38 +0000575/// bit sets. This code only analyzes bits in Mask, in order to short-circuit
576/// processing.
577/// NOTE: we cannot consider 'undef' to be "IsZero" here. The problem is that
578/// we cannot optimize based on the assumption that it is zero without changing
579/// it to be an explicit zero. If we don't change it to zero, other code could
580/// optimized based on the contradictory assumption that it is non-zero.
581/// Because instcombine aggressively folds operations with undef args anyway,
582/// this won't lose us code quality.
583static void ComputeMaskedBits(Value *V, APInt Mask, APInt& KnownZero,
584 APInt& KnownOne, unsigned Depth = 0) {
Zhou Shengaf4341d2007-03-13 02:23:10 +0000585 assert(V && "No Value?");
586 assert(Depth <= 6 && "Limit Search Depth");
Reid Spenceraa696402007-03-08 01:46:38 +0000587 uint32_t BitWidth = Mask.getBitWidth();
Zhou Shengaf4341d2007-03-13 02:23:10 +0000588 const IntegerType *VTy = cast<IntegerType>(V->getType());
589 assert(VTy->getBitWidth() == BitWidth &&
590 KnownZero.getBitWidth() == BitWidth &&
Reid Spenceraa696402007-03-08 01:46:38 +0000591 KnownOne.getBitWidth() == BitWidth &&
Zhou Shengaf4341d2007-03-13 02:23:10 +0000592 "VTy, Mask, KnownOne and KnownZero should have same BitWidth");
Reid Spenceraa696402007-03-08 01:46:38 +0000593 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
594 // We know all of the bits for a constant!
Zhou Shengaf4341d2007-03-13 02:23:10 +0000595 KnownOne = CI->getValue() & Mask;
Reid Spenceraa696402007-03-08 01:46:38 +0000596 KnownZero = ~KnownOne & Mask;
597 return;
598 }
599
Reid Spenceraa696402007-03-08 01:46:38 +0000600 if (Depth == 6 || Mask == 0)
601 return; // Limit search depth.
602
603 Instruction *I = dyn_cast<Instruction>(V);
604 if (!I) return;
605
Zhou Shengaf4341d2007-03-13 02:23:10 +0000606 KnownZero.clear(); KnownOne.clear(); // Don't know anything.
Reid Spenceraa696402007-03-08 01:46:38 +0000607 APInt KnownZero2(KnownZero), KnownOne2(KnownOne);
Zhou Shengaf4341d2007-03-13 02:23:10 +0000608 Mask &= APInt::getAllOnesValue(BitWidth);
Reid Spenceraa696402007-03-08 01:46:38 +0000609
610 switch (I->getOpcode()) {
611 case Instruction::And:
612 // If either the LHS or the RHS are Zero, the result is zero.
613 ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
614 Mask &= ~KnownZero;
615 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
616 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
617 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
618
619 // Output known-1 bits are only known if set in both the LHS & RHS.
620 KnownOne &= KnownOne2;
621 // Output known-0 are known to be clear if zero in either the LHS | RHS.
622 KnownZero |= KnownZero2;
623 return;
624 case Instruction::Or:
625 ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
626 Mask &= ~KnownOne;
627 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
628 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
629 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
630
631 // Output known-0 bits are only known if clear in both the LHS & RHS.
632 KnownZero &= KnownZero2;
633 // Output known-1 are known to be set if set in either the LHS | RHS.
634 KnownOne |= KnownOne2;
635 return;
636 case Instruction::Xor: {
637 ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
638 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
639 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
640 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
641
642 // Output known-0 bits are known if clear or set in both the LHS & RHS.
643 APInt KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2);
644 // Output known-1 are known to be set if set in only one of the LHS, RHS.
645 KnownOne = (KnownZero & KnownOne2) | (KnownOne & KnownZero2);
646 KnownZero = KnownZeroOut;
647 return;
648 }
649 case Instruction::Select:
650 ComputeMaskedBits(I->getOperand(2), Mask, KnownZero, KnownOne, Depth+1);
651 ComputeMaskedBits(I->getOperand(1), Mask, KnownZero2, KnownOne2, Depth+1);
652 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
653 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
654
655 // Only known if known in both the LHS and RHS.
656 KnownOne &= KnownOne2;
657 KnownZero &= KnownZero2;
658 return;
659 case Instruction::FPTrunc:
660 case Instruction::FPExt:
661 case Instruction::FPToUI:
662 case Instruction::FPToSI:
663 case Instruction::SIToFP:
664 case Instruction::PtrToInt:
665 case Instruction::UIToFP:
666 case Instruction::IntToPtr:
667 return; // Can't work with floating point or pointers
Zhou Shengaf4341d2007-03-13 02:23:10 +0000668 case Instruction::Trunc: {
Reid Spenceraa696402007-03-08 01:46:38 +0000669 // All these have integer operands
Zhou Shengaf4341d2007-03-13 02:23:10 +0000670 uint32_t SrcBitWidth =
671 cast<IntegerType>(I->getOperand(0)->getType())->getBitWidth();
672 ComputeMaskedBits(I->getOperand(0), Mask.zext(SrcBitWidth),
673 KnownZero.zext(SrcBitWidth), KnownOne.zext(SrcBitWidth), Depth+1);
674 KnownZero.trunc(BitWidth);
675 KnownOne.trunc(BitWidth);
Reid Spenceraa696402007-03-08 01:46:38 +0000676 return;
Zhou Shengaf4341d2007-03-13 02:23:10 +0000677 }
Reid Spenceraa696402007-03-08 01:46:38 +0000678 case Instruction::BitCast: {
679 const Type *SrcTy = I->getOperand(0)->getType();
680 if (SrcTy->isInteger()) {
681 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
682 return;
683 }
684 break;
685 }
686 case Instruction::ZExt: {
687 // Compute the bits in the result that are not present in the input.
688 const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
Zhou Sheng387d7b12007-03-08 05:42:00 +0000689 APInt NewBits(APInt::getAllOnesValue(BitWidth).shl(SrcTy->getBitWidth()));
Reid Spenceraa696402007-03-08 01:46:38 +0000690
Zhou Shengaf4341d2007-03-13 02:23:10 +0000691 uint32_t SrcBitWidth = SrcTy->getBitWidth();
692 ComputeMaskedBits(I->getOperand(0), Mask.trunc(SrcBitWidth),
693 KnownZero.trunc(SrcBitWidth), KnownOne.trunc(SrcBitWidth), Depth+1);
Reid Spenceraa696402007-03-08 01:46:38 +0000694 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
695 // The top bits are known to be zero.
Zhou Shengaf4341d2007-03-13 02:23:10 +0000696 KnownZero.zext(BitWidth);
697 KnownOne.zext(BitWidth);
Reid Spenceraa696402007-03-08 01:46:38 +0000698 KnownZero |= NewBits;
699 return;
700 }
701 case Instruction::SExt: {
702 // Compute the bits in the result that are not present in the input.
703 const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
Zhou Sheng387d7b12007-03-08 05:42:00 +0000704 APInt NewBits(APInt::getAllOnesValue(BitWidth).shl(SrcTy->getBitWidth()));
Reid Spenceraa696402007-03-08 01:46:38 +0000705
Zhou Shengaf4341d2007-03-13 02:23:10 +0000706 uint32_t SrcBitWidth = SrcTy->getBitWidth();
707 ComputeMaskedBits(I->getOperand(0), Mask.trunc(SrcBitWidth),
708 KnownZero.trunc(SrcBitWidth), KnownOne.trunc(SrcBitWidth), Depth+1);
Reid Spenceraa696402007-03-08 01:46:38 +0000709 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
Zhou Shengaf4341d2007-03-13 02:23:10 +0000710 KnownZero.zext(BitWidth);
711 KnownOne.zext(BitWidth);
Reid Spenceraa696402007-03-08 01:46:38 +0000712
713 // If the sign bit of the input is known set or clear, then we know the
714 // top bits of the result.
Zhou Shengb3e00c42007-03-12 05:44:52 +0000715 APInt InSignBit(APInt::getSignBit(SrcTy->getBitWidth()));
Zhou Shengaf4341d2007-03-13 02:23:10 +0000716 InSignBit.zext(BitWidth);
Reid Spenceraa696402007-03-08 01:46:38 +0000717 if ((KnownZero & InSignBit) != 0) { // Input sign bit known zero
718 KnownZero |= NewBits;
719 KnownOne &= ~NewBits;
720 } else if ((KnownOne & InSignBit) != 0) { // Input sign bit known set
721 KnownOne |= NewBits;
722 KnownZero &= ~NewBits;
723 } else { // Input sign bit unknown
724 KnownZero &= ~NewBits;
725 KnownOne &= ~NewBits;
726 }
727 return;
728 }
729 case Instruction::Shl:
730 // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0
731 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
732 uint64_t ShiftAmt = SA->getZExtValue();
733 Mask = APIntOps::lshr(Mask, ShiftAmt);
734 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
735 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
Zhou Shengb3e00c42007-03-12 05:44:52 +0000736 KnownZero <<= ShiftAmt;
737 KnownOne <<= ShiftAmt;
Reid Spenceraa696402007-03-08 01:46:38 +0000738 KnownZero |= APInt(BitWidth, 1ULL).shl(ShiftAmt)-1; // low bits known zero.
739 return;
740 }
741 break;
742 case Instruction::LShr:
743 // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
744 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
745 // Compute the new bits that are at the top now.
746 uint64_t ShiftAmt = SA->getZExtValue();
747 APInt HighBits(APInt::getAllOnesValue(BitWidth).shl(BitWidth-ShiftAmt));
748
749 // Unsigned shift right.
Zhou Shengb3e00c42007-03-12 05:44:52 +0000750 Mask <<= ShiftAmt;
Reid Spenceraa696402007-03-08 01:46:38 +0000751 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero,KnownOne,Depth+1);
752 assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?");
753 KnownZero = APIntOps::lshr(KnownZero, ShiftAmt);
754 KnownOne = APIntOps::lshr(KnownOne, ShiftAmt);
755 KnownZero |= HighBits; // high bits known zero.
756 return;
757 }
758 break;
759 case Instruction::AShr:
760 // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
761 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
762 // Compute the new bits that are at the top now.
763 uint64_t ShiftAmt = SA->getZExtValue();
764 APInt HighBits(APInt::getAllOnesValue(BitWidth).shl(BitWidth-ShiftAmt));
765
766 // Signed shift right.
Zhou Shengb3e00c42007-03-12 05:44:52 +0000767 Mask <<= ShiftAmt;
Reid Spenceraa696402007-03-08 01:46:38 +0000768 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero,KnownOne,Depth+1);
769 assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?");
770 KnownZero = APIntOps::lshr(KnownZero, ShiftAmt);
771 KnownOne = APIntOps::lshr(KnownOne, ShiftAmt);
772
773 // Handle the sign bits and adjust to where it is now in the mask.
Zhou Shengb3e00c42007-03-12 05:44:52 +0000774 APInt SignBit(APInt::getSignBit(BitWidth).lshr(ShiftAmt));
Reid Spenceraa696402007-03-08 01:46:38 +0000775
776 if ((KnownZero & SignBit) != 0) { // New bits are known zero.
777 KnownZero |= HighBits;
778 } else if ((KnownOne & SignBit) != 0) { // New bits are known one.
779 KnownOne |= HighBits;
780 }
781 return;
782 }
783 break;
784 }
785}
786
787/// ComputeMaskedBits - Determine which of the bits specified in Mask are
788/// known to be either zero or one and return them in the KnownZero/KnownOne
Chris Lattner4534dd592006-02-09 07:38:58 +0000789/// bitsets. This code only analyzes bits in Mask, in order to short-circuit
790/// processing.
Reid Spenceraa696402007-03-08 01:46:38 +0000791static void ComputeMaskedBits(Value *V, uint64_t Mask, uint64_t &KnownZero,
Chris Lattner4534dd592006-02-09 07:38:58 +0000792 uint64_t &KnownOne, unsigned Depth = 0) {
Chris Lattner0b3557f2005-09-24 23:43:33 +0000793 // Note, we cannot consider 'undef' to be "IsZero" here. The problem is that
794 // we cannot optimize based on the assumption that it is zero without changing
Chris Lattnerc3ebf402006-02-07 07:27:52 +0000795 // it to be an explicit zero. If we don't change it to zero, other code could
Chris Lattner0b3557f2005-09-24 23:43:33 +0000796 // optimized based on the contradictory assumption that it is non-zero.
797 // Because instcombine aggressively folds operations with undef args anyway,
798 // this won't lose us code quality.
Zhou Sheng75b871f2007-01-11 12:24:14 +0000799 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
Chris Lattner4534dd592006-02-09 07:38:58 +0000800 // We know all of the bits for a constant!
Chris Lattner0157e7f2006-02-11 09:31:47 +0000801 KnownOne = CI->getZExtValue() & Mask;
Chris Lattner4534dd592006-02-09 07:38:58 +0000802 KnownZero = ~KnownOne & Mask;
803 return;
804 }
805
806 KnownZero = KnownOne = 0; // Don't know anything.
Chris Lattner92a68652006-02-07 08:05:22 +0000807 if (Depth == 6 || Mask == 0)
Chris Lattner4534dd592006-02-09 07:38:58 +0000808 return; // Limit search depth.
809
810 uint64_t KnownZero2, KnownOne2;
Chris Lattner0157e7f2006-02-11 09:31:47 +0000811 Instruction *I = dyn_cast<Instruction>(V);
812 if (!I) return;
813
Reid Spencera94d3942007-01-19 21:13:56 +0000814 Mask &= cast<IntegerType>(V->getType())->getBitMask();
Chris Lattnerfb296922006-05-04 17:33:35 +0000815
Chris Lattner0157e7f2006-02-11 09:31:47 +0000816 switch (I->getOpcode()) {
817 case Instruction::And:
818 // If either the LHS or the RHS are Zero, the result is zero.
819 ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
820 Mask &= ~KnownZero;
821 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
822 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
823 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
824
825 // Output known-1 bits are only known if set in both the LHS & RHS.
826 KnownOne &= KnownOne2;
827 // Output known-0 are known to be clear if zero in either the LHS | RHS.
828 KnownZero |= KnownZero2;
829 return;
830 case Instruction::Or:
831 ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
832 Mask &= ~KnownOne;
833 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
834 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
835 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
836
837 // Output known-0 bits are only known if clear in both the LHS & RHS.
838 KnownZero &= KnownZero2;
839 // Output known-1 are known to be set if set in either the LHS | RHS.
840 KnownOne |= KnownOne2;
841 return;
842 case Instruction::Xor: {
843 ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
844 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
845 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
846 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
847
848 // Output known-0 bits are known if clear or set in both the LHS & RHS.
849 uint64_t KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2);
850 // Output known-1 are known to be set if set in only one of the LHS, RHS.
851 KnownOne = (KnownZero & KnownOne2) | (KnownOne & KnownZero2);
852 KnownZero = KnownZeroOut;
853 return;
854 }
855 case Instruction::Select:
856 ComputeMaskedBits(I->getOperand(2), Mask, KnownZero, KnownOne, Depth+1);
857 ComputeMaskedBits(I->getOperand(1), Mask, KnownZero2, KnownOne2, Depth+1);
858 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
859 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
860
861 // Only known if known in both the LHS and RHS.
862 KnownOne &= KnownOne2;
863 KnownZero &= KnownZero2;
864 return;
Reid Spencer6c38f0b2006-11-27 01:05:10 +0000865 case Instruction::FPTrunc:
866 case Instruction::FPExt:
867 case Instruction::FPToUI:
868 case Instruction::FPToSI:
869 case Instruction::SIToFP:
870 case Instruction::PtrToInt:
871 case Instruction::UIToFP:
872 case Instruction::IntToPtr:
873 return; // Can't work with floating point or pointers
874 case Instruction::Trunc:
875 // All these have integer operands
876 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
877 return;
878 case Instruction::BitCast: {
Chris Lattner0157e7f2006-02-11 09:31:47 +0000879 const Type *SrcTy = I->getOperand(0)->getType();
Chris Lattner03c49532007-01-15 02:27:26 +0000880 if (SrcTy->isInteger()) {
Chris Lattner0157e7f2006-02-11 09:31:47 +0000881 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
Chris Lattner4534dd592006-02-09 07:38:58 +0000882 return;
883 }
Reid Spencer6c38f0b2006-11-27 01:05:10 +0000884 break;
885 }
886 case Instruction::ZExt: {
887 // Compute the bits in the result that are not present in the input.
Reid Spencera94d3942007-01-19 21:13:56 +0000888 const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
889 uint64_t NotIn = ~SrcTy->getBitMask();
890 uint64_t NewBits = cast<IntegerType>(I->getType())->getBitMask() & NotIn;
Chris Lattner62010c42005-10-09 06:36:35 +0000891
Reid Spencera94d3942007-01-19 21:13:56 +0000892 Mask &= SrcTy->getBitMask();
Reid Spencer6c38f0b2006-11-27 01:05:10 +0000893 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
894 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
895 // The top bits are known to be zero.
896 KnownZero |= NewBits;
897 return;
898 }
899 case Instruction::SExt: {
900 // Compute the bits in the result that are not present in the input.
Reid Spencera94d3942007-01-19 21:13:56 +0000901 const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
902 uint64_t NotIn = ~SrcTy->getBitMask();
903 uint64_t NewBits = cast<IntegerType>(I->getType())->getBitMask() & NotIn;
Reid Spencer6c38f0b2006-11-27 01:05:10 +0000904
Reid Spencera94d3942007-01-19 21:13:56 +0000905 Mask &= SrcTy->getBitMask();
Reid Spencer6c38f0b2006-11-27 01:05:10 +0000906 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
907 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
Chris Lattner92a68652006-02-07 08:05:22 +0000908
Reid Spencer6c38f0b2006-11-27 01:05:10 +0000909 // If the sign bit of the input is known set or clear, then we know the
910 // top bits of the result.
911 uint64_t InSignBit = 1ULL << (SrcTy->getPrimitiveSizeInBits()-1);
912 if (KnownZero & InSignBit) { // Input sign bit known zero
913 KnownZero |= NewBits;
914 KnownOne &= ~NewBits;
915 } else if (KnownOne & InSignBit) { // Input sign bit known set
916 KnownOne |= NewBits;
917 KnownZero &= ~NewBits;
918 } else { // Input sign bit unknown
919 KnownZero &= ~NewBits;
920 KnownOne &= ~NewBits;
Chris Lattner0157e7f2006-02-11 09:31:47 +0000921 }
922 return;
923 }
924 case Instruction::Shl:
925 // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0
Reid Spencere0fc4df2006-10-20 07:07:24 +0000926 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
927 uint64_t ShiftAmt = SA->getZExtValue();
928 Mask >>= ShiftAmt;
Chris Lattner0157e7f2006-02-11 09:31:47 +0000929 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
930 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
Reid Spencere0fc4df2006-10-20 07:07:24 +0000931 KnownZero <<= ShiftAmt;
932 KnownOne <<= ShiftAmt;
933 KnownZero |= (1ULL << ShiftAmt)-1; // low bits known zero.
Chris Lattner0157e7f2006-02-11 09:31:47 +0000934 return;
935 }
936 break;
Reid Spencerfdff9382006-11-08 06:47:33 +0000937 case Instruction::LShr:
Chris Lattner0157e7f2006-02-11 09:31:47 +0000938 // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
Reid Spencere0fc4df2006-10-20 07:07:24 +0000939 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
Chris Lattner0157e7f2006-02-11 09:31:47 +0000940 // Compute the new bits that are at the top now.
Reid Spencere0fc4df2006-10-20 07:07:24 +0000941 uint64_t ShiftAmt = SA->getZExtValue();
942 uint64_t HighBits = (1ULL << ShiftAmt)-1;
943 HighBits <<= I->getType()->getPrimitiveSizeInBits()-ShiftAmt;
Chris Lattner0157e7f2006-02-11 09:31:47 +0000944
Reid Spencerfdff9382006-11-08 06:47:33 +0000945 // Unsigned shift right.
946 Mask <<= ShiftAmt;
947 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero,KnownOne,Depth+1);
948 assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?");
949 KnownZero >>= ShiftAmt;
950 KnownOne >>= ShiftAmt;
951 KnownZero |= HighBits; // high bits known zero.
952 return;
953 }
954 break;
955 case Instruction::AShr:
956 // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
957 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
958 // Compute the new bits that are at the top now.
959 uint64_t ShiftAmt = SA->getZExtValue();
960 uint64_t HighBits = (1ULL << ShiftAmt)-1;
961 HighBits <<= I->getType()->getPrimitiveSizeInBits()-ShiftAmt;
962
963 // Signed shift right.
964 Mask <<= ShiftAmt;
965 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero,KnownOne,Depth+1);
966 assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?");
967 KnownZero >>= ShiftAmt;
968 KnownOne >>= ShiftAmt;
Chris Lattner0157e7f2006-02-11 09:31:47 +0000969
Reid Spencerfdff9382006-11-08 06:47:33 +0000970 // Handle the sign bits.
971 uint64_t SignBit = 1ULL << (I->getType()->getPrimitiveSizeInBits()-1);
972 SignBit >>= ShiftAmt; // Adjust to where it is now in the mask.
Chris Lattner0157e7f2006-02-11 09:31:47 +0000973
Reid Spencerfdff9382006-11-08 06:47:33 +0000974 if (KnownZero & SignBit) { // New bits are known zero.
975 KnownZero |= HighBits;
976 } else if (KnownOne & SignBit) { // New bits are known one.
977 KnownOne |= HighBits;
Chris Lattner4534dd592006-02-09 07:38:58 +0000978 }
979 return;
Chris Lattner62010c42005-10-09 06:36:35 +0000980 }
Chris Lattner0157e7f2006-02-11 09:31:47 +0000981 break;
Chris Lattner0b3557f2005-09-24 23:43:33 +0000982 }
Chris Lattner92a68652006-02-07 08:05:22 +0000983}
984
985/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
986/// this predicate to simplify operations downstream. Mask is known to be zero
987/// for bits that V cannot have.
988static bool MaskedValueIsZero(Value *V, uint64_t Mask, unsigned Depth = 0) {
Chris Lattner4534dd592006-02-09 07:38:58 +0000989 uint64_t KnownZero, KnownOne;
990 ComputeMaskedBits(V, Mask, KnownZero, KnownOne, Depth);
991 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
992 return (KnownZero & Mask) == Mask;
Chris Lattner0b3557f2005-09-24 23:43:33 +0000993}
994
Chris Lattnerd1bce952007-03-13 14:27:42 +0000995#if 0
Reid Spencerbb5741f2007-03-08 01:52:58 +0000996/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
997/// this predicate to simplify operations downstream. Mask is known to be zero
998/// for bits that V cannot have.
999static bool MaskedValueIsZero(Value *V, const APInt& Mask, unsigned Depth = 0) {
Zhou Shengbe171ee2007-03-12 16:54:56 +00001000 APInt KnownZero(Mask.getBitWidth(), 0), KnownOne(Mask.getBitWidth(), 0);
Reid Spencerbb5741f2007-03-08 01:52:58 +00001001 ComputeMaskedBits(V, Mask, KnownZero, KnownOne, Depth);
1002 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
1003 return (KnownZero & Mask) == Mask;
1004}
Chris Lattnerd1bce952007-03-13 14:27:42 +00001005#endif
Reid Spencerbb5741f2007-03-08 01:52:58 +00001006
Chris Lattner0157e7f2006-02-11 09:31:47 +00001007/// ShrinkDemandedConstant - Check to see if the specified operand of the
1008/// specified instruction is a constant integer. If so, check to see if there
1009/// are any bits set in the constant that are not demanded. If so, shrink the
1010/// constant and return true.
1011static bool ShrinkDemandedConstant(Instruction *I, unsigned OpNo,
1012 uint64_t Demanded) {
1013 ConstantInt *OpC = dyn_cast<ConstantInt>(I->getOperand(OpNo));
1014 if (!OpC) return false;
1015
1016 // If there are no bits set that aren't demanded, nothing to do.
1017 if ((~Demanded & OpC->getZExtValue()) == 0)
1018 return false;
1019
1020 // This is producing any bits that are not needed, shrink the RHS.
1021 uint64_t Val = Demanded & OpC->getZExtValue();
Zhou Sheng75b871f2007-01-11 12:24:14 +00001022 I->setOperand(OpNo, ConstantInt::get(OpC->getType(), Val));
Chris Lattner0157e7f2006-02-11 09:31:47 +00001023 return true;
1024}
1025
Reid Spencerd9281782007-03-12 17:15:10 +00001026/// ShrinkDemandedConstant - Check to see if the specified operand of the
1027/// specified instruction is a constant integer. If so, check to see if there
1028/// are any bits set in the constant that are not demanded. If so, shrink the
1029/// constant and return true.
1030static bool ShrinkDemandedConstant(Instruction *I, unsigned OpNo,
1031 APInt Demanded) {
1032 assert(I && "No instruction?");
1033 assert(OpNo < I->getNumOperands() && "Operand index too large");
1034
1035 // If the operand is not a constant integer, nothing to do.
1036 ConstantInt *OpC = dyn_cast<ConstantInt>(I->getOperand(OpNo));
1037 if (!OpC) return false;
1038
1039 // If there are no bits set that aren't demanded, nothing to do.
1040 Demanded.zextOrTrunc(OpC->getValue().getBitWidth());
1041 if ((~Demanded & OpC->getValue()) == 0)
1042 return false;
1043
1044 // This instruction is producing bits that are not demanded. Shrink the RHS.
1045 Demanded &= OpC->getValue();
1046 I->setOperand(OpNo, ConstantInt::get(Demanded));
1047 return true;
1048}
1049
Chris Lattneree0f2802006-02-12 02:07:56 +00001050// ComputeSignedMinMaxValuesFromKnownBits - Given a signed integer type and a
1051// set of known zero and one bits, compute the maximum and minimum values that
1052// could have the specified known zero and known one bits, returning them in
1053// min/max.
1054static void ComputeSignedMinMaxValuesFromKnownBits(const Type *Ty,
1055 uint64_t KnownZero,
1056 uint64_t KnownOne,
1057 int64_t &Min, int64_t &Max) {
Reid Spencera94d3942007-01-19 21:13:56 +00001058 uint64_t TypeBits = cast<IntegerType>(Ty)->getBitMask();
Chris Lattneree0f2802006-02-12 02:07:56 +00001059 uint64_t UnknownBits = ~(KnownZero|KnownOne) & TypeBits;
1060
1061 uint64_t SignBit = 1ULL << (Ty->getPrimitiveSizeInBits()-1);
1062
1063 // The minimum value is when all unknown bits are zeros, EXCEPT for the sign
1064 // bit if it is unknown.
1065 Min = KnownOne;
1066 Max = KnownOne|UnknownBits;
1067
1068 if (SignBit & UnknownBits) { // Sign bit is unknown
1069 Min |= SignBit;
1070 Max &= ~SignBit;
1071 }
1072
1073 // Sign extend the min/max values.
1074 int ShAmt = 64-Ty->getPrimitiveSizeInBits();
1075 Min = (Min << ShAmt) >> ShAmt;
1076 Max = (Max << ShAmt) >> ShAmt;
1077}
1078
1079// ComputeUnsignedMinMaxValuesFromKnownBits - Given an unsigned integer type and
1080// a set of known zero and one bits, compute the maximum and minimum values that
1081// could have the specified known zero and known one bits, returning them in
1082// min/max.
1083static void ComputeUnsignedMinMaxValuesFromKnownBits(const Type *Ty,
1084 uint64_t KnownZero,
1085 uint64_t KnownOne,
1086 uint64_t &Min,
1087 uint64_t &Max) {
Reid Spencera94d3942007-01-19 21:13:56 +00001088 uint64_t TypeBits = cast<IntegerType>(Ty)->getBitMask();
Chris Lattneree0f2802006-02-12 02:07:56 +00001089 uint64_t UnknownBits = ~(KnownZero|KnownOne) & TypeBits;
1090
1091 // The minimum value is when the unknown bits are all zeros.
1092 Min = KnownOne;
1093 // The maximum value is when the unknown bits are all ones.
1094 Max = KnownOne|UnknownBits;
1095}
Chris Lattner0157e7f2006-02-11 09:31:47 +00001096
1097
1098/// SimplifyDemandedBits - Look at V. At this point, we know that only the
1099/// DemandedMask bits of the result of V are ever used downstream. If we can
1100/// use this information to simplify V, do so and return true. Otherwise,
1101/// analyze the expression and return a mask of KnownOne and KnownZero bits for
1102/// the expression (used to simplify the caller). The KnownZero/One bits may
1103/// only be accurate for those bits in the DemandedMask.
1104bool InstCombiner::SimplifyDemandedBits(Value *V, uint64_t DemandedMask,
1105 uint64_t &KnownZero, uint64_t &KnownOne,
Chris Lattner2590e512006-02-07 06:56:34 +00001106 unsigned Depth) {
Chris Lattnerab2f9132007-03-04 23:16:36 +00001107 const IntegerType *VTy = cast<IntegerType>(V->getType());
Zhou Sheng75b871f2007-01-11 12:24:14 +00001108 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
Chris Lattner0157e7f2006-02-11 09:31:47 +00001109 // We know all of the bits for a constant!
1110 KnownOne = CI->getZExtValue() & DemandedMask;
1111 KnownZero = ~KnownOne & DemandedMask;
1112 return false;
1113 }
1114
1115 KnownZero = KnownOne = 0;
Chris Lattner2590e512006-02-07 06:56:34 +00001116 if (!V->hasOneUse()) { // Other users may use these bits.
Chris Lattner0157e7f2006-02-11 09:31:47 +00001117 if (Depth != 0) { // Not at the root.
1118 // Just compute the KnownZero/KnownOne bits to simplify things downstream.
1119 ComputeMaskedBits(V, DemandedMask, KnownZero, KnownOne, Depth);
Chris Lattner2590e512006-02-07 06:56:34 +00001120 return false;
Chris Lattner0157e7f2006-02-11 09:31:47 +00001121 }
Chris Lattner2590e512006-02-07 06:56:34 +00001122 // If this is the root being simplified, allow it to have multiple uses,
Chris Lattner0157e7f2006-02-11 09:31:47 +00001123 // just set the DemandedMask to all bits.
Chris Lattnerab2f9132007-03-04 23:16:36 +00001124 DemandedMask = VTy->getBitMask();
Chris Lattner0157e7f2006-02-11 09:31:47 +00001125 } else if (DemandedMask == 0) { // Not demanding any bits from V.
Chris Lattnerab2f9132007-03-04 23:16:36 +00001126 if (V != UndefValue::get(VTy))
1127 return UpdateValueUsesWith(V, UndefValue::get(VTy));
Chris Lattner92a68652006-02-07 08:05:22 +00001128 return false;
Chris Lattner2590e512006-02-07 06:56:34 +00001129 } else if (Depth == 6) { // Limit search depth.
1130 return false;
1131 }
1132
1133 Instruction *I = dyn_cast<Instruction>(V);
1134 if (!I) return false; // Only analyze instructions.
1135
Chris Lattnerab2f9132007-03-04 23:16:36 +00001136 DemandedMask &= VTy->getBitMask();
Chris Lattnerfb296922006-05-04 17:33:35 +00001137
Reid Spencer6c38f0b2006-11-27 01:05:10 +00001138 uint64_t KnownZero2 = 0, KnownOne2 = 0;
Chris Lattner2590e512006-02-07 06:56:34 +00001139 switch (I->getOpcode()) {
1140 default: break;
1141 case Instruction::And:
Chris Lattner0157e7f2006-02-11 09:31:47 +00001142 // If either the LHS or the RHS are Zero, the result is zero.
1143 if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
1144 KnownZero, KnownOne, Depth+1))
1145 return true;
1146 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
1147
1148 // If something is known zero on the RHS, the bits aren't demanded on the
1149 // LHS.
1150 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask & ~KnownZero,
1151 KnownZero2, KnownOne2, Depth+1))
1152 return true;
1153 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
1154
Reid Spencer6c38f0b2006-11-27 01:05:10 +00001155 // If all of the demanded bits are known 1 on one side, return the other.
Chris Lattner0157e7f2006-02-11 09:31:47 +00001156 // These bits cannot contribute to the result of the 'and'.
1157 if ((DemandedMask & ~KnownZero2 & KnownOne) == (DemandedMask & ~KnownZero2))
1158 return UpdateValueUsesWith(I, I->getOperand(0));
1159 if ((DemandedMask & ~KnownZero & KnownOne2) == (DemandedMask & ~KnownZero))
1160 return UpdateValueUsesWith(I, I->getOperand(1));
Chris Lattner5b2edb12006-02-12 08:02:11 +00001161
1162 // If all of the demanded bits in the inputs are known zeros, return zero.
1163 if ((DemandedMask & (KnownZero|KnownZero2)) == DemandedMask)
Chris Lattnerab2f9132007-03-04 23:16:36 +00001164 return UpdateValueUsesWith(I, Constant::getNullValue(VTy));
Chris Lattner5b2edb12006-02-12 08:02:11 +00001165
Chris Lattner0157e7f2006-02-11 09:31:47 +00001166 // If the RHS is a constant, see if we can simplify it.
Chris Lattner5b2edb12006-02-12 08:02:11 +00001167 if (ShrinkDemandedConstant(I, 1, DemandedMask & ~KnownZero2))
Chris Lattner0157e7f2006-02-11 09:31:47 +00001168 return UpdateValueUsesWith(I, I);
1169
1170 // Output known-1 bits are only known if set in both the LHS & RHS.
1171 KnownOne &= KnownOne2;
1172 // Output known-0 are known to be clear if zero in either the LHS | RHS.
1173 KnownZero |= KnownZero2;
1174 break;
1175 case Instruction::Or:
1176 if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
1177 KnownZero, KnownOne, Depth+1))
1178 return true;
1179 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
1180 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask & ~KnownOne,
1181 KnownZero2, KnownOne2, Depth+1))
1182 return true;
1183 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
1184
1185 // If all of the demanded bits are known zero on one side, return the other.
1186 // These bits cannot contribute to the result of the 'or'.
Jeff Cohen0add83e2006-02-18 03:20:33 +00001187 if ((DemandedMask & ~KnownOne2 & KnownZero) == (DemandedMask & ~KnownOne2))
Chris Lattner0157e7f2006-02-11 09:31:47 +00001188 return UpdateValueUsesWith(I, I->getOperand(0));
Jeff Cohen0add83e2006-02-18 03:20:33 +00001189 if ((DemandedMask & ~KnownOne & KnownZero2) == (DemandedMask & ~KnownOne))
Chris Lattner0157e7f2006-02-11 09:31:47 +00001190 return UpdateValueUsesWith(I, I->getOperand(1));
Chris Lattner5b2edb12006-02-12 08:02:11 +00001191
1192 // If all of the potentially set bits on one side are known to be set on
1193 // the other side, just use the 'other' side.
1194 if ((DemandedMask & (~KnownZero) & KnownOne2) ==
1195 (DemandedMask & (~KnownZero)))
1196 return UpdateValueUsesWith(I, I->getOperand(0));
Nate Begeman8a77efe2006-02-16 21:11:51 +00001197 if ((DemandedMask & (~KnownZero2) & KnownOne) ==
1198 (DemandedMask & (~KnownZero2)))
1199 return UpdateValueUsesWith(I, I->getOperand(1));
Chris Lattner0157e7f2006-02-11 09:31:47 +00001200
1201 // If the RHS is a constant, see if we can simplify it.
1202 if (ShrinkDemandedConstant(I, 1, DemandedMask))
1203 return UpdateValueUsesWith(I, I);
1204
1205 // Output known-0 bits are only known if clear in both the LHS & RHS.
1206 KnownZero &= KnownZero2;
1207 // Output known-1 are known to be set if set in either the LHS | RHS.
1208 KnownOne |= KnownOne2;
1209 break;
1210 case Instruction::Xor: {
1211 if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
1212 KnownZero, KnownOne, Depth+1))
1213 return true;
1214 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
1215 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
1216 KnownZero2, KnownOne2, Depth+1))
1217 return true;
1218 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
1219
1220 // If all of the demanded bits are known zero on one side, return the other.
1221 // These bits cannot contribute to the result of the 'xor'.
1222 if ((DemandedMask & KnownZero) == DemandedMask)
1223 return UpdateValueUsesWith(I, I->getOperand(0));
1224 if ((DemandedMask & KnownZero2) == DemandedMask)
1225 return UpdateValueUsesWith(I, I->getOperand(1));
1226
1227 // Output known-0 bits are known if clear or set in both the LHS & RHS.
1228 uint64_t KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2);
1229 // Output known-1 are known to be set if set in only one of the LHS, RHS.
1230 uint64_t KnownOneOut = (KnownZero & KnownOne2) | (KnownOne & KnownZero2);
1231
Chris Lattner8e9a7b72006-11-27 19:55:07 +00001232 // If all of the demanded bits are known to be zero on one side or the
1233 // other, turn this into an *inclusive* or.
Chris Lattner5b2edb12006-02-12 08:02:11 +00001234 // e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
Chris Lattner8e9a7b72006-11-27 19:55:07 +00001235 if ((DemandedMask & ~KnownZero & ~KnownZero2) == 0) {
1236 Instruction *Or =
1237 BinaryOperator::createOr(I->getOperand(0), I->getOperand(1),
1238 I->getName());
1239 InsertNewInstBefore(Or, *I);
1240 return UpdateValueUsesWith(I, Or);
Chris Lattner2590e512006-02-07 06:56:34 +00001241 }
Chris Lattner0157e7f2006-02-11 09:31:47 +00001242
Chris Lattner5b2edb12006-02-12 08:02:11 +00001243 // If all of the demanded bits on one side are known, and all of the set
1244 // bits on that side are also known to be set on the other side, turn this
1245 // into an AND, as we know the bits will be cleared.
1246 // e.g. (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
1247 if ((DemandedMask & (KnownZero|KnownOne)) == DemandedMask) { // all known
1248 if ((KnownOne & KnownOne2) == KnownOne) {
Chris Lattnerab2f9132007-03-04 23:16:36 +00001249 Constant *AndC = ConstantInt::get(VTy, ~KnownOne & DemandedMask);
Chris Lattner5b2edb12006-02-12 08:02:11 +00001250 Instruction *And =
1251 BinaryOperator::createAnd(I->getOperand(0), AndC, "tmp");
1252 InsertNewInstBefore(And, *I);
1253 return UpdateValueUsesWith(I, And);
1254 }
1255 }
1256
Chris Lattner0157e7f2006-02-11 09:31:47 +00001257 // If the RHS is a constant, see if we can simplify it.
1258 // FIXME: for XOR, we prefer to force bits to 1 if they will make a -1.
1259 if (ShrinkDemandedConstant(I, 1, DemandedMask))
1260 return UpdateValueUsesWith(I, I);
1261
1262 KnownZero = KnownZeroOut;
1263 KnownOne = KnownOneOut;
1264 break;
1265 }
1266 case Instruction::Select:
1267 if (SimplifyDemandedBits(I->getOperand(2), DemandedMask,
1268 KnownZero, KnownOne, Depth+1))
1269 return true;
1270 if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
1271 KnownZero2, KnownOne2, Depth+1))
1272 return true;
1273 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
1274 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
1275
1276 // If the operands are constants, see if we can simplify them.
1277 if (ShrinkDemandedConstant(I, 1, DemandedMask))
1278 return UpdateValueUsesWith(I, I);
1279 if (ShrinkDemandedConstant(I, 2, DemandedMask))
1280 return UpdateValueUsesWith(I, I);
1281
1282 // Only known if known in both the LHS and RHS.
1283 KnownOne &= KnownOne2;
1284 KnownZero &= KnownZero2;
1285 break;
Reid Spencer6c38f0b2006-11-27 01:05:10 +00001286 case Instruction::Trunc:
1287 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
1288 KnownZero, KnownOne, Depth+1))
1289 return true;
1290 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
1291 break;
1292 case Instruction::BitCast:
Chris Lattner03c49532007-01-15 02:27:26 +00001293 if (!I->getOperand(0)->getType()->isInteger())
Reid Spencer6c38f0b2006-11-27 01:05:10 +00001294 return false;
Chris Lattner850465d2006-09-16 03:14:10 +00001295
Reid Spencer6c38f0b2006-11-27 01:05:10 +00001296 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
1297 KnownZero, KnownOne, Depth+1))
1298 return true;
1299 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
1300 break;
1301 case Instruction::ZExt: {
1302 // Compute the bits in the result that are not present in the input.
Reid Spencera94d3942007-01-19 21:13:56 +00001303 const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
1304 uint64_t NotIn = ~SrcTy->getBitMask();
Chris Lattnerab2f9132007-03-04 23:16:36 +00001305 uint64_t NewBits = VTy->getBitMask() & NotIn;
Chris Lattner0157e7f2006-02-11 09:31:47 +00001306
Reid Spencera94d3942007-01-19 21:13:56 +00001307 DemandedMask &= SrcTy->getBitMask();
Reid Spencer6c38f0b2006-11-27 01:05:10 +00001308 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
1309 KnownZero, KnownOne, Depth+1))
1310 return true;
1311 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
1312 // The top bits are known to be zero.
1313 KnownZero |= NewBits;
1314 break;
1315 }
1316 case Instruction::SExt: {
1317 // Compute the bits in the result that are not present in the input.
Reid Spencera94d3942007-01-19 21:13:56 +00001318 const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
1319 uint64_t NotIn = ~SrcTy->getBitMask();
Chris Lattnerab2f9132007-03-04 23:16:36 +00001320 uint64_t NewBits = VTy->getBitMask() & NotIn;
Reid Spencer6c38f0b2006-11-27 01:05:10 +00001321
1322 // Get the sign bit for the source type
1323 uint64_t InSignBit = 1ULL << (SrcTy->getPrimitiveSizeInBits()-1);
Reid Spencera94d3942007-01-19 21:13:56 +00001324 int64_t InputDemandedBits = DemandedMask & SrcTy->getBitMask();
Chris Lattner7d852282006-02-13 22:41:07 +00001325
Reid Spencer6c38f0b2006-11-27 01:05:10 +00001326 // If any of the sign extended bits are demanded, we know that the sign
1327 // bit is demanded.
1328 if (NewBits & DemandedMask)
1329 InputDemandedBits |= InSignBit;
Chris Lattner7d852282006-02-13 22:41:07 +00001330
Reid Spencer6c38f0b2006-11-27 01:05:10 +00001331 if (SimplifyDemandedBits(I->getOperand(0), InputDemandedBits,
1332 KnownZero, KnownOne, Depth+1))
1333 return true;
1334 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
Chris Lattner0157e7f2006-02-11 09:31:47 +00001335
Reid Spencer6c38f0b2006-11-27 01:05:10 +00001336 // If the sign bit of the input is known set or clear, then we know the
1337 // top bits of the result.
Chris Lattner2590e512006-02-07 06:56:34 +00001338
Reid Spencer6c38f0b2006-11-27 01:05:10 +00001339 // If the input sign bit is known zero, or if the NewBits are not demanded
1340 // convert this into a zero extension.
1341 if ((KnownZero & InSignBit) || (NewBits & ~DemandedMask) == NewBits) {
1342 // Convert to ZExt cast
Chris Lattnerab2f9132007-03-04 23:16:36 +00001343 CastInst *NewCast = new ZExtInst(I->getOperand(0), VTy, I->getName(), I);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00001344 return UpdateValueUsesWith(I, NewCast);
1345 } else if (KnownOne & InSignBit) { // Input sign bit known set
1346 KnownOne |= NewBits;
1347 KnownZero &= ~NewBits;
1348 } else { // Input sign bit unknown
1349 KnownZero &= ~NewBits;
1350 KnownOne &= ~NewBits;
Chris Lattner2590e512006-02-07 06:56:34 +00001351 }
Chris Lattner0157e7f2006-02-11 09:31:47 +00001352 break;
Chris Lattner2590e512006-02-07 06:56:34 +00001353 }
Chris Lattner6e2c15c2006-11-09 05:12:27 +00001354 case Instruction::Add:
1355 // If there is a constant on the RHS, there are a variety of xformations
1356 // we can do.
1357 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
1358 // If null, this should be simplified elsewhere. Some of the xforms here
1359 // won't work if the RHS is zero.
1360 if (RHS->isNullValue())
1361 break;
1362
1363 // Figure out what the input bits are. If the top bits of the and result
1364 // are not demanded, then the add doesn't demand them from its input
1365 // either.
1366
1367 // Shift the demanded mask up so that it's at the top of the uint64_t.
Chris Lattnerab2f9132007-03-04 23:16:36 +00001368 unsigned BitWidth = VTy->getPrimitiveSizeInBits();
Chris Lattner6e2c15c2006-11-09 05:12:27 +00001369 unsigned NLZ = CountLeadingZeros_64(DemandedMask << (64-BitWidth));
1370
1371 // If the top bit of the output is demanded, demand everything from the
1372 // input. Otherwise, we demand all the input bits except NLZ top bits.
Jeff Cohen223004c2007-01-08 20:17:17 +00001373 uint64_t InDemandedBits = ~0ULL >> (64-BitWidth+NLZ);
Chris Lattner6e2c15c2006-11-09 05:12:27 +00001374
1375 // Find information about known zero/one bits in the input.
1376 if (SimplifyDemandedBits(I->getOperand(0), InDemandedBits,
1377 KnownZero2, KnownOne2, Depth+1))
1378 return true;
1379
1380 // If the RHS of the add has bits set that can't affect the input, reduce
1381 // the constant.
1382 if (ShrinkDemandedConstant(I, 1, InDemandedBits))
1383 return UpdateValueUsesWith(I, I);
1384
1385 // Avoid excess work.
1386 if (KnownZero2 == 0 && KnownOne2 == 0)
1387 break;
1388
1389 // Turn it into OR if input bits are zero.
1390 if ((KnownZero2 & RHS->getZExtValue()) == RHS->getZExtValue()) {
1391 Instruction *Or =
1392 BinaryOperator::createOr(I->getOperand(0), I->getOperand(1),
1393 I->getName());
1394 InsertNewInstBefore(Or, *I);
1395 return UpdateValueUsesWith(I, Or);
1396 }
1397
1398 // We can say something about the output known-zero and known-one bits,
1399 // depending on potential carries from the input constant and the
1400 // unknowns. For example if the LHS is known to have at most the 0x0F0F0
1401 // bits set and the RHS constant is 0x01001, then we know we have a known
1402 // one mask of 0x00001 and a known zero mask of 0xE0F0E.
1403
1404 // To compute this, we first compute the potential carry bits. These are
1405 // the bits which may be modified. I'm not aware of a better way to do
1406 // this scan.
1407 uint64_t RHSVal = RHS->getZExtValue();
1408
1409 bool CarryIn = false;
1410 uint64_t CarryBits = 0;
1411 uint64_t CurBit = 1;
1412 for (unsigned i = 0; i != BitWidth; ++i, CurBit <<= 1) {
1413 // Record the current carry in.
1414 if (CarryIn) CarryBits |= CurBit;
1415
1416 bool CarryOut;
1417
1418 // This bit has a carry out unless it is "zero + zero" or
1419 // "zero + anything" with no carry in.
1420 if ((KnownZero2 & CurBit) && ((RHSVal & CurBit) == 0)) {
1421 CarryOut = false; // 0 + 0 has no carry out, even with carry in.
1422 } else if (!CarryIn &&
1423 ((KnownZero2 & CurBit) || ((RHSVal & CurBit) == 0))) {
1424 CarryOut = false; // 0 + anything has no carry out if no carry in.
1425 } else {
1426 // Otherwise, we have to assume we have a carry out.
1427 CarryOut = true;
1428 }
1429
1430 // This stage's carry out becomes the next stage's carry-in.
1431 CarryIn = CarryOut;
1432 }
1433
1434 // Now that we know which bits have carries, compute the known-1/0 sets.
1435
1436 // Bits are known one if they are known zero in one operand and one in the
1437 // other, and there is no input carry.
1438 KnownOne = ((KnownZero2 & RHSVal) | (KnownOne2 & ~RHSVal)) & ~CarryBits;
1439
1440 // Bits are known zero if they are known zero in both operands and there
1441 // is no input carry.
1442 KnownZero = KnownZero2 & ~RHSVal & ~CarryBits;
Chris Lattner5fdded12007-03-05 00:02:29 +00001443 } else {
1444 // If the high-bits of this ADD are not demanded, then it does not demand
1445 // the high bits of its LHS or RHS.
1446 if ((DemandedMask & VTy->getSignBit()) == 0) {
1447 // Right fill the mask of bits for this ADD to demand the most
1448 // significant bit and all those below it.
1449 unsigned NLZ = CountLeadingZeros_64(DemandedMask);
1450 uint64_t DemandedFromOps = ~0ULL >> NLZ;
1451 if (SimplifyDemandedBits(I->getOperand(0), DemandedFromOps,
1452 KnownZero2, KnownOne2, Depth+1))
1453 return true;
1454 if (SimplifyDemandedBits(I->getOperand(1), DemandedFromOps,
1455 KnownZero2, KnownOne2, Depth+1))
1456 return true;
1457 }
1458 }
1459 break;
1460 case Instruction::Sub:
1461 // If the high-bits of this SUB are not demanded, then it does not demand
1462 // the high bits of its LHS or RHS.
1463 if ((DemandedMask & VTy->getSignBit()) == 0) {
1464 // Right fill the mask of bits for this SUB to demand the most
1465 // significant bit and all those below it.
1466 unsigned NLZ = CountLeadingZeros_64(DemandedMask);
1467 uint64_t DemandedFromOps = ~0ULL >> NLZ;
1468 if (SimplifyDemandedBits(I->getOperand(0), DemandedFromOps,
1469 KnownZero2, KnownOne2, Depth+1))
1470 return true;
1471 if (SimplifyDemandedBits(I->getOperand(1), DemandedFromOps,
1472 KnownZero2, KnownOne2, Depth+1))
1473 return true;
Chris Lattner6e2c15c2006-11-09 05:12:27 +00001474 }
1475 break;
Chris Lattner2590e512006-02-07 06:56:34 +00001476 case Instruction::Shl:
Reid Spencere0fc4df2006-10-20 07:07:24 +00001477 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
1478 uint64_t ShiftAmt = SA->getZExtValue();
1479 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask >> ShiftAmt,
Chris Lattner0157e7f2006-02-11 09:31:47 +00001480 KnownZero, KnownOne, Depth+1))
1481 return true;
1482 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
Reid Spencere0fc4df2006-10-20 07:07:24 +00001483 KnownZero <<= ShiftAmt;
1484 KnownOne <<= ShiftAmt;
1485 KnownZero |= (1ULL << ShiftAmt) - 1; // low bits known zero.
Chris Lattner0157e7f2006-02-11 09:31:47 +00001486 }
Chris Lattner2590e512006-02-07 06:56:34 +00001487 break;
Reid Spencerfdff9382006-11-08 06:47:33 +00001488 case Instruction::LShr:
1489 // For a logical shift right
1490 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
1491 unsigned ShiftAmt = SA->getZExtValue();
1492
1493 // Compute the new bits that are at the top now.
1494 uint64_t HighBits = (1ULL << ShiftAmt)-1;
Chris Lattnerab2f9132007-03-04 23:16:36 +00001495 HighBits <<= VTy->getBitWidth() - ShiftAmt;
1496 uint64_t TypeMask = VTy->getBitMask();
Reid Spencerfdff9382006-11-08 06:47:33 +00001497 // Unsigned shift right.
1498 if (SimplifyDemandedBits(I->getOperand(0),
1499 (DemandedMask << ShiftAmt) & TypeMask,
1500 KnownZero, KnownOne, Depth+1))
1501 return true;
1502 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
1503 KnownZero &= TypeMask;
1504 KnownOne &= TypeMask;
1505 KnownZero >>= ShiftAmt;
1506 KnownOne >>= ShiftAmt;
1507 KnownZero |= HighBits; // high bits known zero.
1508 }
1509 break;
1510 case Instruction::AShr:
Chris Lattner420c4bc2006-09-18 04:31:40 +00001511 // If this is an arithmetic shift right and only the low-bit is set, we can
1512 // always convert this into a logical shr, even if the shift amount is
1513 // variable. The low bit of the shift cannot be an input sign bit unless
1514 // the shift amount is >= the size of the datatype, which is undefined.
Reid Spencerfdff9382006-11-08 06:47:33 +00001515 if (DemandedMask == 1) {
1516 // Perform the logical shift right.
Reid Spencer0d5f9232007-02-02 14:08:20 +00001517 Value *NewVal = BinaryOperator::createLShr(
Reid Spencer2341c222007-02-02 02:16:23 +00001518 I->getOperand(0), I->getOperand(1), I->getName());
Reid Spencer00c482b2006-10-26 19:19:06 +00001519 InsertNewInstBefore(cast<Instruction>(NewVal), *I);
Chris Lattner420c4bc2006-09-18 04:31:40 +00001520 return UpdateValueUsesWith(I, NewVal);
1521 }
1522
Reid Spencere0fc4df2006-10-20 07:07:24 +00001523 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
1524 unsigned ShiftAmt = SA->getZExtValue();
Chris Lattner0157e7f2006-02-11 09:31:47 +00001525
1526 // Compute the new bits that are at the top now.
Reid Spencere0fc4df2006-10-20 07:07:24 +00001527 uint64_t HighBits = (1ULL << ShiftAmt)-1;
Chris Lattnerab2f9132007-03-04 23:16:36 +00001528 HighBits <<= VTy->getBitWidth() - ShiftAmt;
1529 uint64_t TypeMask = VTy->getBitMask();
Reid Spencerfdff9382006-11-08 06:47:33 +00001530 // Signed shift right.
1531 if (SimplifyDemandedBits(I->getOperand(0),
1532 (DemandedMask << ShiftAmt) & TypeMask,
1533 KnownZero, KnownOne, Depth+1))
1534 return true;
1535 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
1536 KnownZero &= TypeMask;
1537 KnownOne &= TypeMask;
1538 KnownZero >>= ShiftAmt;
1539 KnownOne >>= ShiftAmt;
Chris Lattner0157e7f2006-02-11 09:31:47 +00001540
Reid Spencerfdff9382006-11-08 06:47:33 +00001541 // Handle the sign bits.
Chris Lattnerab2f9132007-03-04 23:16:36 +00001542 uint64_t SignBit = 1ULL << (VTy->getBitWidth()-1);
Reid Spencerfdff9382006-11-08 06:47:33 +00001543 SignBit >>= ShiftAmt; // Adjust to where it is now in the mask.
Chris Lattner0157e7f2006-02-11 09:31:47 +00001544
Reid Spencerfdff9382006-11-08 06:47:33 +00001545 // If the input sign bit is known to be zero, or if none of the top bits
1546 // are demanded, turn this into an unsigned shift right.
1547 if ((KnownZero & SignBit) || (HighBits & ~DemandedMask) == HighBits) {
1548 // Perform the logical shift right.
Reid Spencer0d5f9232007-02-02 14:08:20 +00001549 Value *NewVal = BinaryOperator::createLShr(
Reid Spencer2341c222007-02-02 02:16:23 +00001550 I->getOperand(0), SA, I->getName());
Reid Spencerfdff9382006-11-08 06:47:33 +00001551 InsertNewInstBefore(cast<Instruction>(NewVal), *I);
1552 return UpdateValueUsesWith(I, NewVal);
1553 } else if (KnownOne & SignBit) { // New bits are known one.
1554 KnownOne |= HighBits;
Chris Lattner2590e512006-02-07 06:56:34 +00001555 }
Chris Lattner0157e7f2006-02-11 09:31:47 +00001556 }
Chris Lattner2590e512006-02-07 06:56:34 +00001557 break;
1558 }
Chris Lattner0157e7f2006-02-11 09:31:47 +00001559
1560 // If the client is only demanding bits that we know, return the known
1561 // constant.
1562 if ((DemandedMask & (KnownZero|KnownOne)) == DemandedMask)
Chris Lattnerab2f9132007-03-04 23:16:36 +00001563 return UpdateValueUsesWith(I, ConstantInt::get(VTy, KnownOne));
Chris Lattner2590e512006-02-07 06:56:34 +00001564 return false;
1565}
1566
Reid Spencer1791f232007-03-12 17:25:59 +00001567/// SimplifyDemandedBits - This function attempts to replace V with a simpler
1568/// value based on the demanded bits. When this function is called, it is known
1569/// that only the bits set in DemandedMask of the result of V are ever used
1570/// downstream. Consequently, depending on the mask and V, it may be possible
1571/// to replace V with a constant or one of its operands. In such cases, this
1572/// function does the replacement and returns true. In all other cases, it
1573/// returns false after analyzing the expression and setting KnownOne and known
1574/// to be one in the expression. KnownZero contains all the bits that are known
1575/// to be zero in the expression. These are provided to potentially allow the
1576/// caller (which might recursively be SimplifyDemandedBits itself) to simplify
1577/// the expression. KnownOne and KnownZero always follow the invariant that
1578/// KnownOne & KnownZero == 0. That is, a bit can't be both 1 and 0. Note that
1579/// the bits in KnownOne and KnownZero may only be accurate for those bits set
1580/// in DemandedMask. Note also that the bitwidth of V, DemandedMask, KnownZero
1581/// and KnownOne must all be the same.
1582bool InstCombiner::SimplifyDemandedBits(Value *V, APInt DemandedMask,
1583 APInt& KnownZero, APInt& KnownOne,
1584 unsigned Depth) {
1585 assert(V != 0 && "Null pointer of Value???");
1586 assert(Depth <= 6 && "Limit Search Depth");
1587 uint32_t BitWidth = DemandedMask.getBitWidth();
1588 const IntegerType *VTy = cast<IntegerType>(V->getType());
1589 assert(VTy->getBitWidth() == BitWidth &&
1590 KnownZero.getBitWidth() == BitWidth &&
1591 KnownOne.getBitWidth() == BitWidth &&
1592 "Value *V, DemandedMask, KnownZero and KnownOne \
1593 must have same BitWidth");
1594 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
1595 // We know all of the bits for a constant!
1596 KnownOne = CI->getValue() & DemandedMask;
1597 KnownZero = ~KnownOne & DemandedMask;
1598 return false;
1599 }
1600
Zhou Shengb9128442007-03-14 03:21:24 +00001601 KnownZero.clear();
1602 KnownOne.clear();
Reid Spencer1791f232007-03-12 17:25:59 +00001603 if (!V->hasOneUse()) { // Other users may use these bits.
1604 if (Depth != 0) { // Not at the root.
1605 // Just compute the KnownZero/KnownOne bits to simplify things downstream.
1606 ComputeMaskedBits(V, DemandedMask, KnownZero, KnownOne, Depth);
1607 return false;
1608 }
1609 // If this is the root being simplified, allow it to have multiple uses,
1610 // just set the DemandedMask to all bits.
1611 DemandedMask = APInt::getAllOnesValue(BitWidth);
1612 } else if (DemandedMask == 0) { // Not demanding any bits from V.
1613 if (V != UndefValue::get(VTy))
1614 return UpdateValueUsesWith(V, UndefValue::get(VTy));
1615 return false;
1616 } else if (Depth == 6) { // Limit search depth.
1617 return false;
1618 }
1619
1620 Instruction *I = dyn_cast<Instruction>(V);
1621 if (!I) return false; // Only analyze instructions.
1622
1623 DemandedMask &= APInt::getAllOnesValue(BitWidth);
1624
1625 APInt LHSKnownZero(BitWidth, 0), LHSKnownOne(BitWidth, 0);
1626 APInt &RHSKnownZero = KnownZero, &RHSKnownOne = KnownOne;
1627 switch (I->getOpcode()) {
1628 default: break;
1629 case Instruction::And:
1630 // If either the LHS or the RHS are Zero, the result is zero.
1631 if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
1632 RHSKnownZero, RHSKnownOne, Depth+1))
1633 return true;
1634 assert((RHSKnownZero & RHSKnownOne) == 0 &&
1635 "Bits known to be one AND zero?");
1636
1637 // If something is known zero on the RHS, the bits aren't demanded on the
1638 // LHS.
1639 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask & ~RHSKnownZero,
1640 LHSKnownZero, LHSKnownOne, Depth+1))
1641 return true;
1642 assert((LHSKnownZero & LHSKnownOne) == 0 &&
1643 "Bits known to be one AND zero?");
1644
1645 // If all of the demanded bits are known 1 on one side, return the other.
1646 // These bits cannot contribute to the result of the 'and'.
1647 if ((DemandedMask & ~LHSKnownZero & RHSKnownOne) ==
1648 (DemandedMask & ~LHSKnownZero))
1649 return UpdateValueUsesWith(I, I->getOperand(0));
1650 if ((DemandedMask & ~RHSKnownZero & LHSKnownOne) ==
1651 (DemandedMask & ~RHSKnownZero))
1652 return UpdateValueUsesWith(I, I->getOperand(1));
1653
1654 // If all of the demanded bits in the inputs are known zeros, return zero.
1655 if ((DemandedMask & (RHSKnownZero|LHSKnownZero)) == DemandedMask)
1656 return UpdateValueUsesWith(I, Constant::getNullValue(VTy));
1657
1658 // If the RHS is a constant, see if we can simplify it.
1659 if (ShrinkDemandedConstant(I, 1, DemandedMask & ~LHSKnownZero))
1660 return UpdateValueUsesWith(I, I);
1661
1662 // Output known-1 bits are only known if set in both the LHS & RHS.
1663 RHSKnownOne &= LHSKnownOne;
1664 // Output known-0 are known to be clear if zero in either the LHS | RHS.
1665 RHSKnownZero |= LHSKnownZero;
1666 break;
1667 case Instruction::Or:
1668 // If either the LHS or the RHS are One, the result is One.
1669 if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
1670 RHSKnownZero, RHSKnownOne, Depth+1))
1671 return true;
1672 assert((RHSKnownZero & RHSKnownOne) == 0 &&
1673 "Bits known to be one AND zero?");
1674 // If something is known one on the RHS, the bits aren't demanded on the
1675 // LHS.
1676 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask & ~RHSKnownOne,
1677 LHSKnownZero, LHSKnownOne, Depth+1))
1678 return true;
1679 assert((LHSKnownZero & LHSKnownOne) == 0 &&
1680 "Bits known to be one AND zero?");
1681
1682 // If all of the demanded bits are known zero on one side, return the other.
1683 // These bits cannot contribute to the result of the 'or'.
1684 if ((DemandedMask & ~LHSKnownOne & RHSKnownZero) ==
1685 (DemandedMask & ~LHSKnownOne))
1686 return UpdateValueUsesWith(I, I->getOperand(0));
1687 if ((DemandedMask & ~RHSKnownOne & LHSKnownZero) ==
1688 (DemandedMask & ~RHSKnownOne))
1689 return UpdateValueUsesWith(I, I->getOperand(1));
1690
1691 // If all of the potentially set bits on one side are known to be set on
1692 // the other side, just use the 'other' side.
1693 if ((DemandedMask & (~RHSKnownZero) & LHSKnownOne) ==
1694 (DemandedMask & (~RHSKnownZero)))
1695 return UpdateValueUsesWith(I, I->getOperand(0));
1696 if ((DemandedMask & (~LHSKnownZero) & RHSKnownOne) ==
1697 (DemandedMask & (~LHSKnownZero)))
1698 return UpdateValueUsesWith(I, I->getOperand(1));
1699
1700 // If the RHS is a constant, see if we can simplify it.
1701 if (ShrinkDemandedConstant(I, 1, DemandedMask))
1702 return UpdateValueUsesWith(I, I);
1703
1704 // Output known-0 bits are only known if clear in both the LHS & RHS.
1705 RHSKnownZero &= LHSKnownZero;
1706 // Output known-1 are known to be set if set in either the LHS | RHS.
1707 RHSKnownOne |= LHSKnownOne;
1708 break;
1709 case Instruction::Xor: {
1710 if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
1711 RHSKnownZero, RHSKnownOne, Depth+1))
1712 return true;
1713 assert((RHSKnownZero & RHSKnownOne) == 0 &&
1714 "Bits known to be one AND zero?");
1715 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
1716 LHSKnownZero, LHSKnownOne, Depth+1))
1717 return true;
1718 assert((LHSKnownZero & LHSKnownOne) == 0 &&
1719 "Bits known to be one AND zero?");
1720
1721 // If all of the demanded bits are known zero on one side, return the other.
1722 // These bits cannot contribute to the result of the 'xor'.
1723 if ((DemandedMask & RHSKnownZero) == DemandedMask)
1724 return UpdateValueUsesWith(I, I->getOperand(0));
1725 if ((DemandedMask & LHSKnownZero) == DemandedMask)
1726 return UpdateValueUsesWith(I, I->getOperand(1));
1727
1728 // Output known-0 bits are known if clear or set in both the LHS & RHS.
1729 APInt KnownZeroOut = (RHSKnownZero & LHSKnownZero) |
1730 (RHSKnownOne & LHSKnownOne);
1731 // Output known-1 are known to be set if set in only one of the LHS, RHS.
1732 APInt KnownOneOut = (RHSKnownZero & LHSKnownOne) |
1733 (RHSKnownOne & LHSKnownZero);
1734
1735 // If all of the demanded bits are known to be zero on one side or the
1736 // other, turn this into an *inclusive* or.
1737 // e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
1738 if ((DemandedMask & ~RHSKnownZero & ~LHSKnownZero) == 0) {
1739 Instruction *Or =
1740 BinaryOperator::createOr(I->getOperand(0), I->getOperand(1),
1741 I->getName());
1742 InsertNewInstBefore(Or, *I);
1743 return UpdateValueUsesWith(I, Or);
1744 }
1745
1746 // If all of the demanded bits on one side are known, and all of the set
1747 // bits on that side are also known to be set on the other side, turn this
1748 // into an AND, as we know the bits will be cleared.
1749 // e.g. (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
1750 if ((DemandedMask & (RHSKnownZero|RHSKnownOne)) == DemandedMask) {
1751 // all known
1752 if ((RHSKnownOne & LHSKnownOne) == RHSKnownOne) {
1753 Constant *AndC = ConstantInt::get(~RHSKnownOne & DemandedMask);
1754 Instruction *And =
1755 BinaryOperator::createAnd(I->getOperand(0), AndC, "tmp");
1756 InsertNewInstBefore(And, *I);
1757 return UpdateValueUsesWith(I, And);
1758 }
1759 }
1760
1761 // If the RHS is a constant, see if we can simplify it.
1762 // FIXME: for XOR, we prefer to force bits to 1 if they will make a -1.
1763 if (ShrinkDemandedConstant(I, 1, DemandedMask))
1764 return UpdateValueUsesWith(I, I);
1765
1766 RHSKnownZero = KnownZeroOut;
1767 RHSKnownOne = KnownOneOut;
1768 break;
1769 }
1770 case Instruction::Select:
1771 if (SimplifyDemandedBits(I->getOperand(2), DemandedMask,
1772 RHSKnownZero, RHSKnownOne, Depth+1))
1773 return true;
1774 if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
1775 LHSKnownZero, LHSKnownOne, Depth+1))
1776 return true;
1777 assert((RHSKnownZero & RHSKnownOne) == 0 &&
1778 "Bits known to be one AND zero?");
1779 assert((LHSKnownZero & LHSKnownOne) == 0 &&
1780 "Bits known to be one AND zero?");
1781
1782 // If the operands are constants, see if we can simplify them.
1783 if (ShrinkDemandedConstant(I, 1, DemandedMask))
1784 return UpdateValueUsesWith(I, I);
1785 if (ShrinkDemandedConstant(I, 2, DemandedMask))
1786 return UpdateValueUsesWith(I, I);
1787
1788 // Only known if known in both the LHS and RHS.
1789 RHSKnownOne &= LHSKnownOne;
1790 RHSKnownZero &= LHSKnownZero;
1791 break;
1792 case Instruction::Trunc: {
1793 uint32_t truncBf =
1794 cast<IntegerType>(I->getOperand(0)->getType())->getBitWidth();
1795 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask.zext(truncBf),
1796 RHSKnownZero.zext(truncBf), RHSKnownOne.zext(truncBf), Depth+1))
1797 return true;
1798 DemandedMask.trunc(BitWidth);
1799 RHSKnownZero.trunc(BitWidth);
1800 RHSKnownOne.trunc(BitWidth);
1801 assert((RHSKnownZero & RHSKnownOne) == 0 &&
1802 "Bits known to be one AND zero?");
1803 break;
1804 }
1805 case Instruction::BitCast:
1806 if (!I->getOperand(0)->getType()->isInteger())
1807 return false;
1808
1809 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
1810 RHSKnownZero, RHSKnownOne, Depth+1))
1811 return true;
1812 assert((RHSKnownZero & RHSKnownOne) == 0 &&
1813 "Bits known to be one AND zero?");
1814 break;
1815 case Instruction::ZExt: {
1816 // Compute the bits in the result that are not present in the input.
1817 const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
1818 APInt NewBits(APInt::getAllOnesValue(BitWidth).shl(SrcTy->getBitWidth()));
1819
1820 DemandedMask &= SrcTy->getMask().zext(BitWidth);
1821 uint32_t zextBf = SrcTy->getBitWidth();
1822 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask.trunc(zextBf),
1823 RHSKnownZero.trunc(zextBf), RHSKnownOne.trunc(zextBf), Depth+1))
1824 return true;
1825 DemandedMask.zext(BitWidth);
1826 RHSKnownZero.zext(BitWidth);
1827 RHSKnownOne.zext(BitWidth);
1828 assert((RHSKnownZero & RHSKnownOne) == 0 &&
1829 "Bits known to be one AND zero?");
1830 // The top bits are known to be zero.
1831 RHSKnownZero |= NewBits;
1832 break;
1833 }
1834 case Instruction::SExt: {
1835 // Compute the bits in the result that are not present in the input.
1836 const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
1837 APInt NewBits(APInt::getAllOnesValue(BitWidth).shl(SrcTy->getBitWidth()));
1838
1839 // Get the sign bit for the source type
1840 APInt InSignBit(APInt::getSignBit(SrcTy->getPrimitiveSizeInBits()));
1841 InSignBit.zext(BitWidth);
1842 APInt InputDemandedBits = DemandedMask &
1843 SrcTy->getMask().zext(BitWidth);
1844
1845 // If any of the sign extended bits are demanded, we know that the sign
1846 // bit is demanded.
1847 if ((NewBits & DemandedMask) != 0)
1848 InputDemandedBits |= InSignBit;
1849
1850 uint32_t sextBf = SrcTy->getBitWidth();
1851 if (SimplifyDemandedBits(I->getOperand(0), InputDemandedBits.trunc(sextBf),
1852 RHSKnownZero.trunc(sextBf), RHSKnownOne.trunc(sextBf), Depth+1))
1853 return true;
1854 InputDemandedBits.zext(BitWidth);
1855 RHSKnownZero.zext(BitWidth);
1856 RHSKnownOne.zext(BitWidth);
1857 assert((RHSKnownZero & RHSKnownOne) == 0 &&
1858 "Bits known to be one AND zero?");
1859
1860 // If the sign bit of the input is known set or clear, then we know the
1861 // top bits of the result.
1862
1863 // If the input sign bit is known zero, or if the NewBits are not demanded
1864 // convert this into a zero extension.
1865 if ((RHSKnownZero & InSignBit) != 0 || (NewBits & ~DemandedMask) == NewBits)
1866 {
1867 // Convert to ZExt cast
1868 CastInst *NewCast = new ZExtInst(I->getOperand(0), VTy, I->getName(), I);
1869 return UpdateValueUsesWith(I, NewCast);
1870 } else if ((RHSKnownOne & InSignBit) != 0) { // Input sign bit known set
1871 RHSKnownOne |= NewBits;
1872 RHSKnownZero &= ~NewBits;
1873 } else { // Input sign bit unknown
1874 RHSKnownZero &= ~NewBits;
1875 RHSKnownOne &= ~NewBits;
1876 }
1877 break;
1878 }
1879 case Instruction::Add: {
1880 // Figure out what the input bits are. If the top bits of the and result
1881 // are not demanded, then the add doesn't demand them from its input
1882 // either.
1883 unsigned NLZ = DemandedMask.countLeadingZeros();
1884
1885 // If there is a constant on the RHS, there are a variety of xformations
1886 // we can do.
1887 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
1888 // If null, this should be simplified elsewhere. Some of the xforms here
1889 // won't work if the RHS is zero.
1890 if (RHS->isZero())
1891 break;
1892
1893 // If the top bit of the output is demanded, demand everything from the
1894 // input. Otherwise, we demand all the input bits except NLZ top bits.
1895 APInt InDemandedBits(APInt::getAllOnesValue(BitWidth).lshr(NLZ));
1896
1897 // Find information about known zero/one bits in the input.
1898 if (SimplifyDemandedBits(I->getOperand(0), InDemandedBits,
1899 LHSKnownZero, LHSKnownOne, Depth+1))
1900 return true;
1901
1902 // If the RHS of the add has bits set that can't affect the input, reduce
1903 // the constant.
1904 if (ShrinkDemandedConstant(I, 1, InDemandedBits))
1905 return UpdateValueUsesWith(I, I);
1906
1907 // Avoid excess work.
1908 if (LHSKnownZero == 0 && LHSKnownOne == 0)
1909 break;
1910
1911 // Turn it into OR if input bits are zero.
1912 if ((LHSKnownZero & RHS->getValue()) == RHS->getValue()) {
1913 Instruction *Or =
1914 BinaryOperator::createOr(I->getOperand(0), I->getOperand(1),
1915 I->getName());
1916 InsertNewInstBefore(Or, *I);
1917 return UpdateValueUsesWith(I, Or);
1918 }
1919
1920 // We can say something about the output known-zero and known-one bits,
1921 // depending on potential carries from the input constant and the
1922 // unknowns. For example if the LHS is known to have at most the 0x0F0F0
1923 // bits set and the RHS constant is 0x01001, then we know we have a known
1924 // one mask of 0x00001 and a known zero mask of 0xE0F0E.
1925
1926 // To compute this, we first compute the potential carry bits. These are
1927 // the bits which may be modified. I'm not aware of a better way to do
1928 // this scan.
1929 APInt RHSVal(RHS->getValue());
1930
1931 bool CarryIn = false;
1932 APInt CarryBits(BitWidth, 0);
1933 const uint64_t *LHSKnownZeroRawVal = LHSKnownZero.getRawData(),
1934 *RHSRawVal = RHSVal.getRawData();
1935 for (uint32_t i = 0; i != RHSVal.getNumWords(); ++i) {
1936 uint64_t AddVal = ~LHSKnownZeroRawVal[i] + RHSRawVal[i],
1937 XorVal = ~LHSKnownZeroRawVal[i] ^ RHSRawVal[i];
1938 uint64_t WordCarryBits = AddVal ^ XorVal + CarryIn;
1939 if (AddVal < RHSRawVal[i])
1940 CarryIn = true;
1941 else
1942 CarryIn = false;
1943 CarryBits.setWordToValue(i, WordCarryBits);
1944 }
1945
1946 // Now that we know which bits have carries, compute the known-1/0 sets.
1947
1948 // Bits are known one if they are known zero in one operand and one in the
1949 // other, and there is no input carry.
1950 RHSKnownOne = ((LHSKnownZero & RHSVal) |
1951 (LHSKnownOne & ~RHSVal)) & ~CarryBits;
1952
1953 // Bits are known zero if they are known zero in both operands and there
1954 // is no input carry.
1955 RHSKnownZero = LHSKnownZero & ~RHSVal & ~CarryBits;
1956 } else {
1957 // If the high-bits of this ADD are not demanded, then it does not demand
1958 // the high bits of its LHS or RHS.
1959 if ((DemandedMask & APInt::getSignBit(BitWidth)) == 0) {
1960 // Right fill the mask of bits for this ADD to demand the most
1961 // significant bit and all those below it.
1962 APInt DemandedFromOps = APInt::getAllOnesValue(BitWidth).lshr(NLZ);
1963 if (SimplifyDemandedBits(I->getOperand(0), DemandedFromOps,
1964 LHSKnownZero, LHSKnownOne, Depth+1))
1965 return true;
1966 if (SimplifyDemandedBits(I->getOperand(1), DemandedFromOps,
1967 LHSKnownZero, LHSKnownOne, Depth+1))
1968 return true;
1969 }
1970 }
1971 break;
1972 }
1973 case Instruction::Sub:
1974 // If the high-bits of this SUB are not demanded, then it does not demand
1975 // the high bits of its LHS or RHS.
1976 if ((DemandedMask & APInt::getSignBit(BitWidth)) == 0) {
1977 // Right fill the mask of bits for this SUB to demand the most
1978 // significant bit and all those below it.
1979 unsigned NLZ = DemandedMask.countLeadingZeros();
1980 APInt DemandedFromOps(APInt::getAllOnesValue(BitWidth).lshr(NLZ));
1981 if (SimplifyDemandedBits(I->getOperand(0), DemandedFromOps,
1982 LHSKnownZero, LHSKnownOne, Depth+1))
1983 return true;
1984 if (SimplifyDemandedBits(I->getOperand(1), DemandedFromOps,
1985 LHSKnownZero, LHSKnownOne, Depth+1))
1986 return true;
1987 }
1988 break;
1989 case Instruction::Shl:
1990 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
1991 uint64_t ShiftAmt = SA->getZExtValue();
1992 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask.lshr(ShiftAmt),
1993 RHSKnownZero, RHSKnownOne, Depth+1))
1994 return true;
1995 assert((RHSKnownZero & RHSKnownOne) == 0 &&
1996 "Bits known to be one AND zero?");
1997 RHSKnownZero <<= ShiftAmt;
1998 RHSKnownOne <<= ShiftAmt;
1999 // low bits known zero.
Zhou Shengd8c645b2007-03-14 09:07:33 +00002000 if (ShiftAmt)
2001 RHSKnownZero |= APInt::getAllOnesValue(ShiftAmt).zextOrCopy(BitWidth);
Reid Spencer1791f232007-03-12 17:25:59 +00002002 }
2003 break;
2004 case Instruction::LShr:
2005 // For a logical shift right
2006 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
2007 unsigned ShiftAmt = SA->getZExtValue();
2008
2009 APInt TypeMask(APInt::getAllOnesValue(BitWidth));
2010 // Unsigned shift right.
2011 if (SimplifyDemandedBits(I->getOperand(0),
2012 (DemandedMask.shl(ShiftAmt)) & TypeMask,
2013 RHSKnownZero, RHSKnownOne, Depth+1))
2014 return true;
2015 assert((RHSKnownZero & RHSKnownOne) == 0 &&
2016 "Bits known to be one AND zero?");
Reid Spencer1791f232007-03-12 17:25:59 +00002017 RHSKnownZero &= TypeMask;
2018 RHSKnownOne &= TypeMask;
2019 RHSKnownZero = APIntOps::lshr(RHSKnownZero, ShiftAmt);
2020 RHSKnownOne = APIntOps::lshr(RHSKnownOne, ShiftAmt);
Zhou Shengd8c645b2007-03-14 09:07:33 +00002021 if (ShiftAmt) {
2022 // Compute the new bits that are at the top now.
2023 APInt HighBits(APInt::getAllOnesValue(BitWidth).shl(
2024 BitWidth - ShiftAmt));
2025 RHSKnownZero |= HighBits; // high bits known zero.
2026 }
Reid Spencer1791f232007-03-12 17:25:59 +00002027 }
2028 break;
2029 case Instruction::AShr:
2030 // If this is an arithmetic shift right and only the low-bit is set, we can
2031 // always convert this into a logical shr, even if the shift amount is
2032 // variable. The low bit of the shift cannot be an input sign bit unless
2033 // the shift amount is >= the size of the datatype, which is undefined.
2034 if (DemandedMask == 1) {
2035 // Perform the logical shift right.
2036 Value *NewVal = BinaryOperator::createLShr(
2037 I->getOperand(0), I->getOperand(1), I->getName());
2038 InsertNewInstBefore(cast<Instruction>(NewVal), *I);
2039 return UpdateValueUsesWith(I, NewVal);
2040 }
2041
2042 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
2043 unsigned ShiftAmt = SA->getZExtValue();
2044
2045 APInt TypeMask(APInt::getAllOnesValue(BitWidth));
2046 // Signed shift right.
2047 if (SimplifyDemandedBits(I->getOperand(0),
2048 (DemandedMask.shl(ShiftAmt)) & TypeMask,
2049 RHSKnownZero, RHSKnownOne, Depth+1))
2050 return true;
2051 assert((RHSKnownZero & RHSKnownOne) == 0 &&
2052 "Bits known to be one AND zero?");
2053 // Compute the new bits that are at the top now.
Zhou Shengd8c645b2007-03-14 09:07:33 +00002054 APInt HighBits(APInt::getAllOnesValue(BitWidth).shl(BitWidth - ShiftAmt));
Reid Spencer1791f232007-03-12 17:25:59 +00002055 RHSKnownZero &= TypeMask;
2056 RHSKnownOne &= TypeMask;
2057 RHSKnownZero = APIntOps::lshr(RHSKnownZero, ShiftAmt);
2058 RHSKnownOne = APIntOps::lshr(RHSKnownOne, ShiftAmt);
2059
2060 // Handle the sign bits.
2061 APInt SignBit(APInt::getSignBit(BitWidth));
2062 // Adjust to where it is now in the mask.
2063 SignBit = APIntOps::lshr(SignBit, ShiftAmt);
2064
2065 // If the input sign bit is known to be zero, or if none of the top bits
2066 // are demanded, turn this into an unsigned shift right.
2067 if ((RHSKnownZero & SignBit) != 0 ||
2068 (HighBits & ~DemandedMask) == HighBits) {
2069 // Perform the logical shift right.
2070 Value *NewVal = BinaryOperator::createLShr(
2071 I->getOperand(0), SA, I->getName());
2072 InsertNewInstBefore(cast<Instruction>(NewVal), *I);
2073 return UpdateValueUsesWith(I, NewVal);
2074 } else if ((RHSKnownOne & SignBit) != 0) { // New bits are known one.
2075 RHSKnownOne |= HighBits;
2076 }
2077 }
2078 break;
2079 }
2080
2081 // If the client is only demanding bits that we know, return the known
2082 // constant.
2083 if ((DemandedMask & (RHSKnownZero|RHSKnownOne)) == DemandedMask)
2084 return UpdateValueUsesWith(I, ConstantInt::get(RHSKnownOne));
2085 return false;
2086}
2087
Chris Lattner2deeaea2006-10-05 06:55:50 +00002088
2089/// SimplifyDemandedVectorElts - The specified value producecs a vector with
2090/// 64 or fewer elements. DemandedElts contains the set of elements that are
2091/// actually used by the caller. This method analyzes which elements of the
2092/// operand are undef and returns that information in UndefElts.
2093///
2094/// If the information about demanded elements can be used to simplify the
2095/// operation, the operation is simplified, then the resultant value is
2096/// returned. This returns null if no change was made.
2097Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, uint64_t DemandedElts,
2098 uint64_t &UndefElts,
2099 unsigned Depth) {
Reid Spencerd84d35b2007-02-15 02:26:10 +00002100 unsigned VWidth = cast<VectorType>(V->getType())->getNumElements();
Chris Lattner2deeaea2006-10-05 06:55:50 +00002101 assert(VWidth <= 64 && "Vector too wide to analyze!");
2102 uint64_t EltMask = ~0ULL >> (64-VWidth);
2103 assert(DemandedElts != EltMask && (DemandedElts & ~EltMask) == 0 &&
2104 "Invalid DemandedElts!");
2105
2106 if (isa<UndefValue>(V)) {
2107 // If the entire vector is undefined, just return this info.
2108 UndefElts = EltMask;
2109 return 0;
2110 } else if (DemandedElts == 0) { // If nothing is demanded, provide undef.
2111 UndefElts = EltMask;
2112 return UndefValue::get(V->getType());
2113 }
2114
2115 UndefElts = 0;
Reid Spencerd84d35b2007-02-15 02:26:10 +00002116 if (ConstantVector *CP = dyn_cast<ConstantVector>(V)) {
2117 const Type *EltTy = cast<VectorType>(V->getType())->getElementType();
Chris Lattner2deeaea2006-10-05 06:55:50 +00002118 Constant *Undef = UndefValue::get(EltTy);
2119
2120 std::vector<Constant*> Elts;
2121 for (unsigned i = 0; i != VWidth; ++i)
2122 if (!(DemandedElts & (1ULL << i))) { // If not demanded, set to undef.
2123 Elts.push_back(Undef);
2124 UndefElts |= (1ULL << i);
2125 } else if (isa<UndefValue>(CP->getOperand(i))) { // Already undef.
2126 Elts.push_back(Undef);
2127 UndefElts |= (1ULL << i);
2128 } else { // Otherwise, defined.
2129 Elts.push_back(CP->getOperand(i));
2130 }
2131
2132 // If we changed the constant, return it.
Reid Spencerd84d35b2007-02-15 02:26:10 +00002133 Constant *NewCP = ConstantVector::get(Elts);
Chris Lattner2deeaea2006-10-05 06:55:50 +00002134 return NewCP != CP ? NewCP : 0;
2135 } else if (isa<ConstantAggregateZero>(V)) {
Reid Spencerd84d35b2007-02-15 02:26:10 +00002136 // Simplify the CAZ to a ConstantVector where the non-demanded elements are
Chris Lattner2deeaea2006-10-05 06:55:50 +00002137 // set to undef.
Reid Spencerd84d35b2007-02-15 02:26:10 +00002138 const Type *EltTy = cast<VectorType>(V->getType())->getElementType();
Chris Lattner2deeaea2006-10-05 06:55:50 +00002139 Constant *Zero = Constant::getNullValue(EltTy);
2140 Constant *Undef = UndefValue::get(EltTy);
2141 std::vector<Constant*> Elts;
2142 for (unsigned i = 0; i != VWidth; ++i)
2143 Elts.push_back((DemandedElts & (1ULL << i)) ? Zero : Undef);
2144 UndefElts = DemandedElts ^ EltMask;
Reid Spencerd84d35b2007-02-15 02:26:10 +00002145 return ConstantVector::get(Elts);
Chris Lattner2deeaea2006-10-05 06:55:50 +00002146 }
2147
2148 if (!V->hasOneUse()) { // Other users may use these bits.
2149 if (Depth != 0) { // Not at the root.
2150 // TODO: Just compute the UndefElts information recursively.
2151 return false;
2152 }
2153 return false;
2154 } else if (Depth == 10) { // Limit search depth.
2155 return false;
2156 }
2157
2158 Instruction *I = dyn_cast<Instruction>(V);
2159 if (!I) return false; // Only analyze instructions.
2160
2161 bool MadeChange = false;
2162 uint64_t UndefElts2;
2163 Value *TmpV;
2164 switch (I->getOpcode()) {
2165 default: break;
2166
2167 case Instruction::InsertElement: {
2168 // If this is a variable index, we don't know which element it overwrites.
2169 // demand exactly the same input as we produce.
Reid Spencere0fc4df2006-10-20 07:07:24 +00002170 ConstantInt *Idx = dyn_cast<ConstantInt>(I->getOperand(2));
Chris Lattner2deeaea2006-10-05 06:55:50 +00002171 if (Idx == 0) {
2172 // Note that we can't propagate undef elt info, because we don't know
2173 // which elt is getting updated.
2174 TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts,
2175 UndefElts2, Depth+1);
2176 if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
2177 break;
2178 }
2179
2180 // If this is inserting an element that isn't demanded, remove this
2181 // insertelement.
Reid Spencere0fc4df2006-10-20 07:07:24 +00002182 unsigned IdxNo = Idx->getZExtValue();
Chris Lattner2deeaea2006-10-05 06:55:50 +00002183 if (IdxNo >= VWidth || (DemandedElts & (1ULL << IdxNo)) == 0)
2184 return AddSoonDeadInstToWorklist(*I, 0);
2185
2186 // Otherwise, the element inserted overwrites whatever was there, so the
2187 // input demanded set is simpler than the output set.
2188 TmpV = SimplifyDemandedVectorElts(I->getOperand(0),
2189 DemandedElts & ~(1ULL << IdxNo),
2190 UndefElts, Depth+1);
2191 if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
2192
2193 // The inserted element is defined.
2194 UndefElts |= 1ULL << IdxNo;
2195 break;
2196 }
2197
2198 case Instruction::And:
2199 case Instruction::Or:
2200 case Instruction::Xor:
2201 case Instruction::Add:
2202 case Instruction::Sub:
2203 case Instruction::Mul:
2204 // div/rem demand all inputs, because they don't want divide by zero.
2205 TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts,
2206 UndefElts, Depth+1);
2207 if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
2208 TmpV = SimplifyDemandedVectorElts(I->getOperand(1), DemandedElts,
2209 UndefElts2, Depth+1);
2210 if (TmpV) { I->setOperand(1, TmpV); MadeChange = true; }
2211
2212 // Output elements are undefined if both are undefined. Consider things
2213 // like undef&0. The result is known zero, not undef.
2214 UndefElts &= UndefElts2;
2215 break;
2216
2217 case Instruction::Call: {
2218 IntrinsicInst *II = dyn_cast<IntrinsicInst>(I);
2219 if (!II) break;
2220 switch (II->getIntrinsicID()) {
2221 default: break;
2222
2223 // Binary vector operations that work column-wise. A dest element is a
2224 // function of the corresponding input elements from the two inputs.
2225 case Intrinsic::x86_sse_sub_ss:
2226 case Intrinsic::x86_sse_mul_ss:
2227 case Intrinsic::x86_sse_min_ss:
2228 case Intrinsic::x86_sse_max_ss:
2229 case Intrinsic::x86_sse2_sub_sd:
2230 case Intrinsic::x86_sse2_mul_sd:
2231 case Intrinsic::x86_sse2_min_sd:
2232 case Intrinsic::x86_sse2_max_sd:
2233 TmpV = SimplifyDemandedVectorElts(II->getOperand(1), DemandedElts,
2234 UndefElts, Depth+1);
2235 if (TmpV) { II->setOperand(1, TmpV); MadeChange = true; }
2236 TmpV = SimplifyDemandedVectorElts(II->getOperand(2), DemandedElts,
2237 UndefElts2, Depth+1);
2238 if (TmpV) { II->setOperand(2, TmpV); MadeChange = true; }
2239
2240 // If only the low elt is demanded and this is a scalarizable intrinsic,
2241 // scalarize it now.
2242 if (DemandedElts == 1) {
2243 switch (II->getIntrinsicID()) {
2244 default: break;
2245 case Intrinsic::x86_sse_sub_ss:
2246 case Intrinsic::x86_sse_mul_ss:
2247 case Intrinsic::x86_sse2_sub_sd:
2248 case Intrinsic::x86_sse2_mul_sd:
2249 // TODO: Lower MIN/MAX/ABS/etc
2250 Value *LHS = II->getOperand(1);
2251 Value *RHS = II->getOperand(2);
2252 // Extract the element as scalars.
2253 LHS = InsertNewInstBefore(new ExtractElementInst(LHS, 0U,"tmp"), *II);
2254 RHS = InsertNewInstBefore(new ExtractElementInst(RHS, 0U,"tmp"), *II);
2255
2256 switch (II->getIntrinsicID()) {
2257 default: assert(0 && "Case stmts out of sync!");
2258 case Intrinsic::x86_sse_sub_ss:
2259 case Intrinsic::x86_sse2_sub_sd:
2260 TmpV = InsertNewInstBefore(BinaryOperator::createSub(LHS, RHS,
2261 II->getName()), *II);
2262 break;
2263 case Intrinsic::x86_sse_mul_ss:
2264 case Intrinsic::x86_sse2_mul_sd:
2265 TmpV = InsertNewInstBefore(BinaryOperator::createMul(LHS, RHS,
2266 II->getName()), *II);
2267 break;
2268 }
2269
2270 Instruction *New =
2271 new InsertElementInst(UndefValue::get(II->getType()), TmpV, 0U,
2272 II->getName());
2273 InsertNewInstBefore(New, *II);
2274 AddSoonDeadInstToWorklist(*II, 0);
2275 return New;
2276 }
2277 }
2278
2279 // Output elements are undefined if both are undefined. Consider things
2280 // like undef&0. The result is known zero, not undef.
2281 UndefElts &= UndefElts2;
2282 break;
2283 }
2284 break;
2285 }
2286 }
2287 return MadeChange ? I : 0;
2288}
2289
Reid Spencer266e42b2006-12-23 06:05:41 +00002290/// @returns true if the specified compare instruction is
2291/// true when both operands are equal...
2292/// @brief Determine if the ICmpInst returns true if both operands are equal
2293static bool isTrueWhenEqual(ICmpInst &ICI) {
2294 ICmpInst::Predicate pred = ICI.getPredicate();
2295 return pred == ICmpInst::ICMP_EQ || pred == ICmpInst::ICMP_UGE ||
2296 pred == ICmpInst::ICMP_SGE || pred == ICmpInst::ICMP_ULE ||
2297 pred == ICmpInst::ICMP_SLE;
2298}
2299
Chris Lattnerb8b97502003-08-13 19:01:45 +00002300/// AssociativeOpt - Perform an optimization on an associative operator. This
2301/// function is designed to check a chain of associative operators for a
2302/// potential to apply a certain optimization. Since the optimization may be
2303/// applicable if the expression was reassociated, this checks the chain, then
2304/// reassociates the expression as necessary to expose the optimization
2305/// opportunity. This makes use of a special Functor, which must define
2306/// 'shouldApply' and 'apply' methods.
2307///
2308template<typename Functor>
2309Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
2310 unsigned Opcode = Root.getOpcode();
2311 Value *LHS = Root.getOperand(0);
2312
2313 // Quick check, see if the immediate LHS matches...
2314 if (F.shouldApply(LHS))
2315 return F.apply(Root);
2316
2317 // Otherwise, if the LHS is not of the same opcode as the root, return.
2318 Instruction *LHSI = dyn_cast<Instruction>(LHS);
Chris Lattnerf95d9b92003-10-15 16:48:29 +00002319 while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
Chris Lattnerb8b97502003-08-13 19:01:45 +00002320 // Should we apply this transform to the RHS?
2321 bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
2322
2323 // If not to the RHS, check to see if we should apply to the LHS...
2324 if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
2325 cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
2326 ShouldApply = true;
2327 }
2328
2329 // If the functor wants to apply the optimization to the RHS of LHSI,
2330 // reassociate the expression from ((? op A) op B) to (? op (A op B))
2331 if (ShouldApply) {
2332 BasicBlock *BB = Root.getParent();
Misha Brukmanb1c93172005-04-21 23:48:37 +00002333
Chris Lattnerb8b97502003-08-13 19:01:45 +00002334 // Now all of the instructions are in the current basic block, go ahead
2335 // and perform the reassociation.
2336 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
2337
2338 // First move the selected RHS to the LHS of the root...
2339 Root.setOperand(0, LHSI->getOperand(1));
2340
2341 // Make what used to be the LHS of the root be the user of the root...
2342 Value *ExtraOperand = TmpLHSI->getOperand(1);
Chris Lattner284d3b02004-04-16 18:08:07 +00002343 if (&Root == TmpLHSI) {
Chris Lattner8953b902004-04-05 02:10:19 +00002344 Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
2345 return 0;
2346 }
Chris Lattner284d3b02004-04-16 18:08:07 +00002347 Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
Chris Lattnerb8b97502003-08-13 19:01:45 +00002348 TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
Chris Lattner284d3b02004-04-16 18:08:07 +00002349 TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
2350 BasicBlock::iterator ARI = &Root; ++ARI;
2351 BB->getInstList().insert(ARI, TmpLHSI); // Move TmpLHSI to after Root
2352 ARI = Root;
Chris Lattnerb8b97502003-08-13 19:01:45 +00002353
2354 // Now propagate the ExtraOperand down the chain of instructions until we
2355 // get to LHSI.
2356 while (TmpLHSI != LHSI) {
2357 Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
Chris Lattner284d3b02004-04-16 18:08:07 +00002358 // Move the instruction to immediately before the chain we are
2359 // constructing to avoid breaking dominance properties.
2360 NextLHSI->getParent()->getInstList().remove(NextLHSI);
2361 BB->getInstList().insert(ARI, NextLHSI);
2362 ARI = NextLHSI;
2363
Chris Lattnerb8b97502003-08-13 19:01:45 +00002364 Value *NextOp = NextLHSI->getOperand(1);
2365 NextLHSI->setOperand(1, ExtraOperand);
2366 TmpLHSI = NextLHSI;
2367 ExtraOperand = NextOp;
2368 }
Misha Brukmanb1c93172005-04-21 23:48:37 +00002369
Chris Lattnerb8b97502003-08-13 19:01:45 +00002370 // Now that the instructions are reassociated, have the functor perform
2371 // the transformation...
2372 return F.apply(Root);
2373 }
Misha Brukmanb1c93172005-04-21 23:48:37 +00002374
Chris Lattnerb8b97502003-08-13 19:01:45 +00002375 LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
2376 }
2377 return 0;
2378}
2379
2380
2381// AddRHS - Implements: X + X --> X << 1
2382struct AddRHS {
2383 Value *RHS;
2384 AddRHS(Value *rhs) : RHS(rhs) {}
2385 bool shouldApply(Value *LHS) const { return LHS == RHS; }
2386 Instruction *apply(BinaryOperator &Add) const {
Reid Spencer0d5f9232007-02-02 14:08:20 +00002387 return BinaryOperator::createShl(Add.getOperand(0),
Reid Spencer2341c222007-02-02 02:16:23 +00002388 ConstantInt::get(Add.getType(), 1));
Chris Lattnerb8b97502003-08-13 19:01:45 +00002389 }
2390};
2391
2392// AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
2393// iff C1&C2 == 0
2394struct AddMaskingAnd {
2395 Constant *C2;
2396 AddMaskingAnd(Constant *c) : C2(c) {}
2397 bool shouldApply(Value *LHS) const {
Chris Lattnerd4252a72004-07-30 07:50:03 +00002398 ConstantInt *C1;
Misha Brukmanb1c93172005-04-21 23:48:37 +00002399 return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
Chris Lattnerd4252a72004-07-30 07:50:03 +00002400 ConstantExpr::getAnd(C1, C2)->isNullValue();
Chris Lattnerb8b97502003-08-13 19:01:45 +00002401 }
2402 Instruction *apply(BinaryOperator &Add) const {
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00002403 return BinaryOperator::createOr(Add.getOperand(0), Add.getOperand(1));
Chris Lattnerb8b97502003-08-13 19:01:45 +00002404 }
2405};
2406
Chris Lattner86102b82005-01-01 16:22:27 +00002407static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
Chris Lattner183b3362004-04-09 19:05:30 +00002408 InstCombiner *IC) {
Reid Spencer6c38f0b2006-11-27 01:05:10 +00002409 if (CastInst *CI = dyn_cast<CastInst>(&I)) {
Chris Lattner86102b82005-01-01 16:22:27 +00002410 if (Constant *SOC = dyn_cast<Constant>(SO))
Reid Spencer6c38f0b2006-11-27 01:05:10 +00002411 return ConstantExpr::getCast(CI->getOpcode(), SOC, I.getType());
Misha Brukmanb1c93172005-04-21 23:48:37 +00002412
Reid Spencer6c38f0b2006-11-27 01:05:10 +00002413 return IC->InsertNewInstBefore(CastInst::create(
2414 CI->getOpcode(), SO, I.getType(), SO->getName() + ".cast"), I);
Chris Lattner86102b82005-01-01 16:22:27 +00002415 }
2416
Chris Lattner183b3362004-04-09 19:05:30 +00002417 // Figure out if the constant is the left or the right argument.
Chris Lattner86102b82005-01-01 16:22:27 +00002418 bool ConstIsRHS = isa<Constant>(I.getOperand(1));
2419 Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
Chris Lattnerb8b97502003-08-13 19:01:45 +00002420
Chris Lattner183b3362004-04-09 19:05:30 +00002421 if (Constant *SOC = dyn_cast<Constant>(SO)) {
2422 if (ConstIsRHS)
Chris Lattner86102b82005-01-01 16:22:27 +00002423 return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
2424 return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
Chris Lattner183b3362004-04-09 19:05:30 +00002425 }
2426
2427 Value *Op0 = SO, *Op1 = ConstOperand;
2428 if (!ConstIsRHS)
2429 std::swap(Op0, Op1);
2430 Instruction *New;
Chris Lattner86102b82005-01-01 16:22:27 +00002431 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
2432 New = BinaryOperator::create(BO->getOpcode(), Op0, Op1,SO->getName()+".op");
Reid Spencer266e42b2006-12-23 06:05:41 +00002433 else if (CmpInst *CI = dyn_cast<CmpInst>(&I))
2434 New = CmpInst::create(CI->getOpcode(), CI->getPredicate(), Op0, Op1,
2435 SO->getName()+".cmp");
Chris Lattnerf9d96652004-04-10 19:15:56 +00002436 else {
Chris Lattner183b3362004-04-09 19:05:30 +00002437 assert(0 && "Unknown binary instruction type!");
Chris Lattnerf9d96652004-04-10 19:15:56 +00002438 abort();
2439 }
Chris Lattner86102b82005-01-01 16:22:27 +00002440 return IC->InsertNewInstBefore(New, I);
2441}
2442
2443// FoldOpIntoSelect - Given an instruction with a select as one operand and a
2444// constant as the other operand, try to fold the binary operator into the
2445// select arguments. This also works for Cast instructions, which obviously do
2446// not have a second operand.
2447static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
2448 InstCombiner *IC) {
2449 // Don't modify shared select instructions
2450 if (!SI->hasOneUse()) return 0;
2451 Value *TV = SI->getOperand(1);
2452 Value *FV = SI->getOperand(2);
2453
2454 if (isa<Constant>(TV) || isa<Constant>(FV)) {
Chris Lattner374e6592005-04-21 05:43:13 +00002455 // Bool selects with constant operands can be folded to logical ops.
Reid Spencer542964f2007-01-11 18:21:29 +00002456 if (SI->getType() == Type::Int1Ty) return 0;
Chris Lattner374e6592005-04-21 05:43:13 +00002457
Chris Lattner86102b82005-01-01 16:22:27 +00002458 Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
2459 Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
2460
2461 return new SelectInst(SI->getCondition(), SelectTrueVal,
2462 SelectFalseVal);
2463 }
2464 return 0;
Chris Lattner183b3362004-04-09 19:05:30 +00002465}
2466
Chris Lattner6a4adcd2004-09-29 05:07:12 +00002467
2468/// FoldOpIntoPhi - Given a binary operator or cast instruction which has a PHI
2469/// node as operand #0, see if we can fold the instruction into the PHI (which
2470/// is only possible if all operands to the PHI are constants).
2471Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
2472 PHINode *PN = cast<PHINode>(I.getOperand(0));
Chris Lattner7515cab2004-11-14 19:13:23 +00002473 unsigned NumPHIValues = PN->getNumIncomingValues();
Chris Lattner04689872006-09-09 22:02:56 +00002474 if (!PN->hasOneUse() || NumPHIValues == 0) return 0;
Chris Lattner6a4adcd2004-09-29 05:07:12 +00002475
Chris Lattner04689872006-09-09 22:02:56 +00002476 // Check to see if all of the operands of the PHI are constants. If there is
2477 // one non-constant value, remember the BB it is. If there is more than one
Chris Lattnerc4d8e7e2007-02-24 01:03:45 +00002478 // or if *it* is a PHI, bail out.
Chris Lattner04689872006-09-09 22:02:56 +00002479 BasicBlock *NonConstBB = 0;
2480 for (unsigned i = 0; i != NumPHIValues; ++i)
2481 if (!isa<Constant>(PN->getIncomingValue(i))) {
2482 if (NonConstBB) return 0; // More than one non-const value.
Chris Lattnerc4d8e7e2007-02-24 01:03:45 +00002483 if (isa<PHINode>(PN->getIncomingValue(i))) return 0; // Itself a phi.
Chris Lattner04689872006-09-09 22:02:56 +00002484 NonConstBB = PN->getIncomingBlock(i);
2485
2486 // If the incoming non-constant value is in I's block, we have an infinite
2487 // loop.
2488 if (NonConstBB == I.getParent())
2489 return 0;
2490 }
2491
2492 // If there is exactly one non-constant value, we can insert a copy of the
2493 // operation in that block. However, if this is a critical edge, we would be
2494 // inserting the computation one some other paths (e.g. inside a loop). Only
2495 // do this if the pred block is unconditionally branching into the phi block.
2496 if (NonConstBB) {
2497 BranchInst *BI = dyn_cast<BranchInst>(NonConstBB->getTerminator());
2498 if (!BI || !BI->isUnconditional()) return 0;
2499 }
Chris Lattner6a4adcd2004-09-29 05:07:12 +00002500
2501 // Okay, we can do the transformation: create the new PHI node.
Chris Lattner6e0123b2007-02-11 01:23:03 +00002502 PHINode *NewPN = new PHINode(I.getType(), "");
Chris Lattnerd8e20182005-01-29 00:39:08 +00002503 NewPN->reserveOperandSpace(PN->getNumOperands()/2);
Chris Lattner6a4adcd2004-09-29 05:07:12 +00002504 InsertNewInstBefore(NewPN, *PN);
Chris Lattner6e0123b2007-02-11 01:23:03 +00002505 NewPN->takeName(PN);
Chris Lattner6a4adcd2004-09-29 05:07:12 +00002506
2507 // Next, add all of the operands to the PHI.
2508 if (I.getNumOperands() == 2) {
2509 Constant *C = cast<Constant>(I.getOperand(1));
Chris Lattner7515cab2004-11-14 19:13:23 +00002510 for (unsigned i = 0; i != NumPHIValues; ++i) {
Chris Lattner04689872006-09-09 22:02:56 +00002511 Value *InV;
2512 if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
Reid Spencer266e42b2006-12-23 06:05:41 +00002513 if (CmpInst *CI = dyn_cast<CmpInst>(&I))
2514 InV = ConstantExpr::getCompare(CI->getPredicate(), InC, C);
2515 else
2516 InV = ConstantExpr::get(I.getOpcode(), InC, C);
Chris Lattner04689872006-09-09 22:02:56 +00002517 } else {
2518 assert(PN->getIncomingBlock(i) == NonConstBB);
2519 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
2520 InV = BinaryOperator::create(BO->getOpcode(),
2521 PN->getIncomingValue(i), C, "phitmp",
2522 NonConstBB->getTerminator());
Reid Spencer266e42b2006-12-23 06:05:41 +00002523 else if (CmpInst *CI = dyn_cast<CmpInst>(&I))
2524 InV = CmpInst::create(CI->getOpcode(),
2525 CI->getPredicate(),
2526 PN->getIncomingValue(i), C, "phitmp",
2527 NonConstBB->getTerminator());
Chris Lattner04689872006-09-09 22:02:56 +00002528 else
2529 assert(0 && "Unknown binop!");
2530
Chris Lattnerb15e2b12007-03-02 21:28:56 +00002531 AddToWorkList(cast<Instruction>(InV));
Chris Lattner04689872006-09-09 22:02:56 +00002532 }
2533 NewPN->addIncoming(InV, PN->getIncomingBlock(i));
Chris Lattner6a4adcd2004-09-29 05:07:12 +00002534 }
Reid Spencer6c38f0b2006-11-27 01:05:10 +00002535 } else {
2536 CastInst *CI = cast<CastInst>(&I);
2537 const Type *RetTy = CI->getType();
Chris Lattner7515cab2004-11-14 19:13:23 +00002538 for (unsigned i = 0; i != NumPHIValues; ++i) {
Chris Lattner04689872006-09-09 22:02:56 +00002539 Value *InV;
2540 if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
Reid Spencer6c38f0b2006-11-27 01:05:10 +00002541 InV = ConstantExpr::getCast(CI->getOpcode(), InC, RetTy);
Chris Lattner04689872006-09-09 22:02:56 +00002542 } else {
2543 assert(PN->getIncomingBlock(i) == NonConstBB);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00002544 InV = CastInst::create(CI->getOpcode(), PN->getIncomingValue(i),
2545 I.getType(), "phitmp",
2546 NonConstBB->getTerminator());
Chris Lattnerb15e2b12007-03-02 21:28:56 +00002547 AddToWorkList(cast<Instruction>(InV));
Chris Lattner04689872006-09-09 22:02:56 +00002548 }
2549 NewPN->addIncoming(InV, PN->getIncomingBlock(i));
Chris Lattner6a4adcd2004-09-29 05:07:12 +00002550 }
2551 }
2552 return ReplaceInstUsesWith(I, NewPN);
2553}
2554
Chris Lattner113f4f42002-06-25 16:13:24 +00002555Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
Chris Lattnerdcf240a2003-03-10 21:43:22 +00002556 bool Changed = SimplifyCommutative(I);
Chris Lattner113f4f42002-06-25 16:13:24 +00002557 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
Chris Lattner9fa53de2002-05-06 16:49:18 +00002558
Chris Lattnercf4a9962004-04-10 22:01:55 +00002559 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
Chris Lattner81a7a232004-10-16 18:11:37 +00002560 // X + undef -> undef
2561 if (isa<UndefValue>(RHS))
2562 return ReplaceInstUsesWith(I, RHS);
2563
Chris Lattnercf4a9962004-04-10 22:01:55 +00002564 // X + 0 --> X
Chris Lattner7a002fe2006-12-02 00:13:08 +00002565 if (!I.getType()->isFPOrFPVector()) { // NOTE: -0 + +0 = +0.
Chris Lattner7fde91e2005-10-17 17:56:38 +00002566 if (RHSC->isNullValue())
2567 return ReplaceInstUsesWith(I, LHS);
Chris Lattnerda1b1522005-10-17 20:18:38 +00002568 } else if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
2569 if (CFP->isExactlyValue(-0.0))
2570 return ReplaceInstUsesWith(I, LHS);
Chris Lattner7fde91e2005-10-17 17:56:38 +00002571 }
Misha Brukmanb1c93172005-04-21 23:48:37 +00002572
Chris Lattnercf4a9962004-04-10 22:01:55 +00002573 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
Chris Lattner6e2c15c2006-11-09 05:12:27 +00002574 // X + (signbit) --> X ^ signbit
Chris Lattner92a68652006-02-07 08:05:22 +00002575 uint64_t Val = CI->getZExtValue();
Chris Lattner77defba2006-02-07 07:00:41 +00002576 if (Val == (1ULL << (CI->getType()->getPrimitiveSizeInBits()-1)))
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00002577 return BinaryOperator::createXor(LHS, RHS);
Chris Lattner6e2c15c2006-11-09 05:12:27 +00002578
2579 // See if SimplifyDemandedBits can simplify this. This handles stuff like
2580 // (X & 254)+1 -> (X&254)|1
2581 uint64_t KnownZero, KnownOne;
Reid Spencerd84d35b2007-02-15 02:26:10 +00002582 if (!isa<VectorType>(I.getType()) &&
Reid Spencera94d3942007-01-19 21:13:56 +00002583 SimplifyDemandedBits(&I, cast<IntegerType>(I.getType())->getBitMask(),
Chris Lattner6e2c15c2006-11-09 05:12:27 +00002584 KnownZero, KnownOne))
2585 return &I;
Chris Lattnercf4a9962004-04-10 22:01:55 +00002586 }
Chris Lattner6a4adcd2004-09-29 05:07:12 +00002587
2588 if (isa<PHINode>(LHS))
2589 if (Instruction *NV = FoldOpIntoPhi(I))
2590 return NV;
Chris Lattner0b3557f2005-09-24 23:43:33 +00002591
Chris Lattner330628a2006-01-06 17:59:59 +00002592 ConstantInt *XorRHS = 0;
2593 Value *XorLHS = 0;
Chris Lattner4284f642007-01-30 22:32:46 +00002594 if (isa<ConstantInt>(RHSC) &&
2595 match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
Chris Lattner0b3557f2005-09-24 23:43:33 +00002596 unsigned TySizeBits = I.getType()->getPrimitiveSizeInBits();
2597 int64_t RHSSExt = cast<ConstantInt>(RHSC)->getSExtValue();
2598 uint64_t RHSZExt = cast<ConstantInt>(RHSC)->getZExtValue();
2599
2600 uint64_t C0080Val = 1ULL << 31;
2601 int64_t CFF80Val = -C0080Val;
2602 unsigned Size = 32;
2603 do {
2604 if (TySizeBits > Size) {
2605 bool Found = false;
2606 // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
2607 // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
2608 if (RHSSExt == CFF80Val) {
2609 if (XorRHS->getZExtValue() == C0080Val)
2610 Found = true;
2611 } else if (RHSZExt == C0080Val) {
2612 if (XorRHS->getSExtValue() == CFF80Val)
2613 Found = true;
2614 }
2615 if (Found) {
2616 // This is a sign extend if the top bits are known zero.
Chris Lattner4534dd592006-02-09 07:38:58 +00002617 uint64_t Mask = ~0ULL;
Chris Lattnerc3ebf402006-02-07 07:27:52 +00002618 Mask <<= 64-(TySizeBits-Size);
Reid Spencera94d3942007-01-19 21:13:56 +00002619 Mask &= cast<IntegerType>(XorLHS->getType())->getBitMask();
Chris Lattnerc3ebf402006-02-07 07:27:52 +00002620 if (!MaskedValueIsZero(XorLHS, Mask))
Chris Lattner0b3557f2005-09-24 23:43:33 +00002621 Size = 0; // Not a sign ext, but can't be any others either.
2622 goto FoundSExt;
2623 }
2624 }
2625 Size >>= 1;
2626 C0080Val >>= Size;
2627 CFF80Val >>= Size;
2628 } while (Size >= 8);
2629
2630FoundSExt:
2631 const Type *MiddleType = 0;
2632 switch (Size) {
2633 default: break;
Reid Spencerc635f472006-12-31 05:48:39 +00002634 case 32: MiddleType = Type::Int32Ty; break;
2635 case 16: MiddleType = Type::Int16Ty; break;
2636 case 8: MiddleType = Type::Int8Ty; break;
Chris Lattner0b3557f2005-09-24 23:43:33 +00002637 }
2638 if (MiddleType) {
Reid Spencerbb65ebf2006-12-12 23:36:14 +00002639 Instruction *NewTrunc = new TruncInst(XorLHS, MiddleType, "sext");
Chris Lattner0b3557f2005-09-24 23:43:33 +00002640 InsertNewInstBefore(NewTrunc, I);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00002641 return new SExtInst(NewTrunc, I.getType());
Chris Lattner0b3557f2005-09-24 23:43:33 +00002642 }
2643 }
Chris Lattnercf4a9962004-04-10 22:01:55 +00002644 }
Chris Lattner9fa53de2002-05-06 16:49:18 +00002645
Chris Lattnerb8b97502003-08-13 19:01:45 +00002646 // X + X --> X << 1
Chris Lattner03c49532007-01-15 02:27:26 +00002647 if (I.getType()->isInteger() && I.getType() != Type::Int1Ty) {
Chris Lattnerb8b97502003-08-13 19:01:45 +00002648 if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
Chris Lattner47060462005-04-07 17:14:51 +00002649
2650 if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
2651 if (RHSI->getOpcode() == Instruction::Sub)
2652 if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B
2653 return ReplaceInstUsesWith(I, RHSI->getOperand(0));
2654 }
2655 if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
2656 if (LHSI->getOpcode() == Instruction::Sub)
2657 if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B
2658 return ReplaceInstUsesWith(I, LHSI->getOperand(0));
2659 }
Robert Bocchino7b5b86c2004-07-27 21:02:21 +00002660 }
Chris Lattnerede3fe02003-08-13 04:18:28 +00002661
Chris Lattner147e9752002-05-08 22:46:53 +00002662 // -A + B --> B - A
Chris Lattnerbb74e222003-03-10 23:06:50 +00002663 if (Value *V = dyn_castNegVal(LHS))
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00002664 return BinaryOperator::createSub(RHS, V);
Chris Lattner9fa53de2002-05-06 16:49:18 +00002665
2666 // A + -B --> A - B
Chris Lattnerbb74e222003-03-10 23:06:50 +00002667 if (!isa<Constant>(RHS))
2668 if (Value *V = dyn_castNegVal(RHS))
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00002669 return BinaryOperator::createSub(LHS, V);
Chris Lattner260ab202002-04-18 17:39:14 +00002670
Misha Brukmanb1c93172005-04-21 23:48:37 +00002671
Chris Lattner8c3e7b92004-11-13 19:50:12 +00002672 ConstantInt *C2;
2673 if (Value *X = dyn_castFoldableMul(LHS, C2)) {
2674 if (X == RHS) // X*C + X --> X * (C+1)
2675 return BinaryOperator::createMul(RHS, AddOne(C2));
2676
2677 // X*C1 + X*C2 --> X * (C1+C2)
2678 ConstantInt *C1;
2679 if (X == dyn_castFoldableMul(RHS, C1))
2680 return BinaryOperator::createMul(X, ConstantExpr::getAdd(C1, C2));
Chris Lattner57c8d992003-02-18 19:57:07 +00002681 }
2682
2683 // X + X*C --> X * (C+1)
Chris Lattner8c3e7b92004-11-13 19:50:12 +00002684 if (dyn_castFoldableMul(RHS, C2) == LHS)
2685 return BinaryOperator::createMul(LHS, AddOne(C2));
2686
Chris Lattner23eb8ec2007-01-05 02:17:46 +00002687 // X + ~X --> -1 since ~X = -X-1
2688 if (dyn_castNotVal(LHS) == RHS ||
2689 dyn_castNotVal(RHS) == LHS)
2690 return ReplaceInstUsesWith(I, ConstantInt::getAllOnesValue(I.getType()));
2691
Chris Lattner57c8d992003-02-18 19:57:07 +00002692
Chris Lattnerb8b97502003-08-13 19:01:45 +00002693 // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
Chris Lattnerd4252a72004-07-30 07:50:03 +00002694 if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
Chris Lattner23eb8ec2007-01-05 02:17:46 +00002695 if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2)))
2696 return R;
Chris Lattner7fb29e12003-03-11 00:12:48 +00002697
Chris Lattnerb9cde762003-10-02 15:11:26 +00002698 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
Chris Lattner330628a2006-01-06 17:59:59 +00002699 Value *X = 0;
Chris Lattnerd4252a72004-07-30 07:50:03 +00002700 if (match(LHS, m_Not(m_Value(X)))) { // ~X + C --> (C-1) - X
2701 Constant *C= ConstantExpr::getSub(CRHS, ConstantInt::get(I.getType(), 1));
2702 return BinaryOperator::createSub(C, X);
Chris Lattnerb9cde762003-10-02 15:11:26 +00002703 }
Chris Lattnerd4252a72004-07-30 07:50:03 +00002704
Chris Lattnerbff91d92004-10-08 05:07:56 +00002705 // (X & FF00) + xx00 -> (X+xx00) & FF00
2706 if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
2707 Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
2708 if (Anded == CRHS) {
2709 // See if all bits from the first bit set in the Add RHS up are included
2710 // in the mask. First, get the rightmost bit.
Reid Spencere0fc4df2006-10-20 07:07:24 +00002711 uint64_t AddRHSV = CRHS->getZExtValue();
Chris Lattnerbff91d92004-10-08 05:07:56 +00002712
2713 // Form a mask of all bits from the lowest bit added through the top.
2714 uint64_t AddRHSHighBits = ~((AddRHSV & -AddRHSV)-1);
Reid Spencera94d3942007-01-19 21:13:56 +00002715 AddRHSHighBits &= C2->getType()->getBitMask();
Chris Lattnerbff91d92004-10-08 05:07:56 +00002716
2717 // See if the and mask includes all of these bits.
Reid Spencere0fc4df2006-10-20 07:07:24 +00002718 uint64_t AddRHSHighBitsAnd = AddRHSHighBits & C2->getZExtValue();
Misha Brukmanb1c93172005-04-21 23:48:37 +00002719
Chris Lattnerbff91d92004-10-08 05:07:56 +00002720 if (AddRHSHighBits == AddRHSHighBitsAnd) {
2721 // Okay, the xform is safe. Insert the new add pronto.
2722 Value *NewAdd = InsertNewInstBefore(BinaryOperator::createAdd(X, CRHS,
2723 LHS->getName()), I);
2724 return BinaryOperator::createAnd(NewAdd, C2);
2725 }
2726 }
2727 }
2728
Chris Lattnerd4252a72004-07-30 07:50:03 +00002729 // Try to fold constant add into select arguments.
2730 if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
Chris Lattner86102b82005-01-01 16:22:27 +00002731 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
Chris Lattnerd4252a72004-07-30 07:50:03 +00002732 return R;
Chris Lattnerb9cde762003-10-02 15:11:26 +00002733 }
2734
Reid Spencer7e80b0b2006-10-26 06:15:43 +00002735 // add (cast *A to intptrtype) B ->
2736 // cast (GEP (cast *A to sbyte*) B) ->
2737 // intptrtype
Andrew Lenharth4f339be2006-09-19 18:24:51 +00002738 {
Reid Spencer6c38f0b2006-11-27 01:05:10 +00002739 CastInst *CI = dyn_cast<CastInst>(LHS);
2740 Value *Other = RHS;
Andrew Lenharth4f339be2006-09-19 18:24:51 +00002741 if (!CI) {
2742 CI = dyn_cast<CastInst>(RHS);
2743 Other = LHS;
2744 }
Andrew Lenharth44cb67a2006-09-20 15:37:57 +00002745 if (CI && CI->getType()->isSized() &&
Reid Spencer8f166b02007-01-08 16:32:00 +00002746 (CI->getType()->getPrimitiveSizeInBits() ==
2747 TD->getIntPtrType()->getPrimitiveSizeInBits())
Andrew Lenharth44cb67a2006-09-20 15:37:57 +00002748 && isa<PointerType>(CI->getOperand(0)->getType())) {
Reid Spencer13bc5d72006-12-12 09:18:51 +00002749 Value *I2 = InsertCastBefore(Instruction::BitCast, CI->getOperand(0),
Reid Spencerc635f472006-12-31 05:48:39 +00002750 PointerType::get(Type::Int8Ty), I);
Andrew Lenharth44cb67a2006-09-20 15:37:57 +00002751 I2 = InsertNewInstBefore(new GetElementPtrInst(I2, Other, "ctg2"), I);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00002752 return new PtrToIntInst(I2, CI->getType());
Andrew Lenharth4f339be2006-09-19 18:24:51 +00002753 }
2754 }
2755
Chris Lattner113f4f42002-06-25 16:13:24 +00002756 return Changed ? &I : 0;
Chris Lattner260ab202002-04-18 17:39:14 +00002757}
2758
Chris Lattnerbdb0ce02003-07-22 21:46:59 +00002759// isSignBit - Return true if the value represented by the constant only has the
2760// highest order bit set.
2761static bool isSignBit(ConstantInt *CI) {
Chris Lattnerd1f46d32005-04-24 06:59:08 +00002762 unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
Reid Spencer450434e2007-03-19 20:58:18 +00002763 return CI->getValue() == APInt::getSignBit(NumBits);
Chris Lattnerbdb0ce02003-07-22 21:46:59 +00002764}
2765
Chris Lattner113f4f42002-06-25 16:13:24 +00002766Instruction *InstCombiner::visitSub(BinaryOperator &I) {
Chris Lattner113f4f42002-06-25 16:13:24 +00002767 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00002768
Chris Lattnere6794492002-08-12 21:17:25 +00002769 if (Op0 == Op1) // sub X, X -> 0
2770 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
Chris Lattner260ab202002-04-18 17:39:14 +00002771
Chris Lattnere6794492002-08-12 21:17:25 +00002772 // If this is a 'B = x-(-A)', change to B = x+A...
Chris Lattnerbb74e222003-03-10 23:06:50 +00002773 if (Value *V = dyn_castNegVal(Op1))
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00002774 return BinaryOperator::createAdd(Op0, V);
Chris Lattner9fa53de2002-05-06 16:49:18 +00002775
Chris Lattner81a7a232004-10-16 18:11:37 +00002776 if (isa<UndefValue>(Op0))
2777 return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
2778 if (isa<UndefValue>(Op1))
2779 return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
2780
Chris Lattner8f2f5982003-11-05 01:06:05 +00002781 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
2782 // Replace (-1 - A) with (~A)...
Chris Lattner3082c5a2003-02-18 19:28:33 +00002783 if (C->isAllOnesValue())
2784 return BinaryOperator::createNot(Op1);
Chris Lattnerad3c4952002-05-09 01:29:19 +00002785
Chris Lattner8f2f5982003-11-05 01:06:05 +00002786 // C - ~X == X + (1+C)
Reid Spencer4fdd96c2005-06-18 17:37:34 +00002787 Value *X = 0;
Chris Lattnerd4252a72004-07-30 07:50:03 +00002788 if (match(Op1, m_Not(m_Value(X))))
2789 return BinaryOperator::createAdd(X,
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00002790 ConstantExpr::getAdd(C, ConstantInt::get(I.getType(), 1)));
Chris Lattner27df1db2007-01-15 07:02:54 +00002791 // -(X >>u 31) -> (X >>s 31)
2792 // -(X >>s 31) -> (X >>u 31)
Chris Lattner022167f2004-03-13 00:11:49 +00002793 if (C->isNullValue()) {
Reid Spencer2341c222007-02-02 02:16:23 +00002794 if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op1))
Reid Spencerfdff9382006-11-08 06:47:33 +00002795 if (SI->getOpcode() == Instruction::LShr) {
Reid Spencere0fc4df2006-10-20 07:07:24 +00002796 if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
Chris Lattner92295c52004-03-12 23:53:13 +00002797 // Check to see if we are shifting out everything but the sign bit.
Reid Spencere0fc4df2006-10-20 07:07:24 +00002798 if (CU->getZExtValue() ==
2799 SI->getType()->getPrimitiveSizeInBits()-1) {
Reid Spencerfdff9382006-11-08 06:47:33 +00002800 // Ok, the transformation is safe. Insert AShr.
Reid Spencer2341c222007-02-02 02:16:23 +00002801 return BinaryOperator::create(Instruction::AShr,
2802 SI->getOperand(0), CU, SI->getName());
Chris Lattner92295c52004-03-12 23:53:13 +00002803 }
2804 }
Reid Spencerfdff9382006-11-08 06:47:33 +00002805 }
2806 else if (SI->getOpcode() == Instruction::AShr) {
2807 if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
2808 // Check to see if we are shifting out everything but the sign bit.
2809 if (CU->getZExtValue() ==
2810 SI->getType()->getPrimitiveSizeInBits()-1) {
Reid Spencerc635f472006-12-31 05:48:39 +00002811 // Ok, the transformation is safe. Insert LShr.
Reid Spencer0d5f9232007-02-02 14:08:20 +00002812 return BinaryOperator::createLShr(
Reid Spencer2341c222007-02-02 02:16:23 +00002813 SI->getOperand(0), CU, SI->getName());
Reid Spencerfdff9382006-11-08 06:47:33 +00002814 }
2815 }
2816 }
Chris Lattner022167f2004-03-13 00:11:49 +00002817 }
Chris Lattner183b3362004-04-09 19:05:30 +00002818
2819 // Try to fold constant sub into select arguments.
2820 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
Chris Lattner86102b82005-01-01 16:22:27 +00002821 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
Chris Lattner183b3362004-04-09 19:05:30 +00002822 return R;
Chris Lattner6a4adcd2004-09-29 05:07:12 +00002823
2824 if (isa<PHINode>(Op0))
2825 if (Instruction *NV = FoldOpIntoPhi(I))
2826 return NV;
Chris Lattner8f2f5982003-11-05 01:06:05 +00002827 }
2828
Chris Lattnera9be4492005-04-07 16:15:25 +00002829 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
2830 if (Op1I->getOpcode() == Instruction::Add &&
Chris Lattner7a002fe2006-12-02 00:13:08 +00002831 !Op0->getType()->isFPOrFPVector()) {
Chris Lattnerc7f3c1a2005-04-07 16:28:01 +00002832 if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
Chris Lattnera9be4492005-04-07 16:15:25 +00002833 return BinaryOperator::createNeg(Op1I->getOperand(1), I.getName());
Chris Lattnerc7f3c1a2005-04-07 16:28:01 +00002834 else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
Chris Lattnera9be4492005-04-07 16:15:25 +00002835 return BinaryOperator::createNeg(Op1I->getOperand(0), I.getName());
Chris Lattnerc7f3c1a2005-04-07 16:28:01 +00002836 else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
2837 if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
2838 // C1-(X+C2) --> (C1-C2)-X
2839 return BinaryOperator::createSub(ConstantExpr::getSub(CI1, CI2),
2840 Op1I->getOperand(0));
2841 }
Chris Lattnera9be4492005-04-07 16:15:25 +00002842 }
2843
Chris Lattnerf95d9b92003-10-15 16:48:29 +00002844 if (Op1I->hasOneUse()) {
Chris Lattner3082c5a2003-02-18 19:28:33 +00002845 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
2846 // is not used by anyone else...
2847 //
Chris Lattnerc2f0aa52004-02-02 20:09:56 +00002848 if (Op1I->getOpcode() == Instruction::Sub &&
Chris Lattner7a002fe2006-12-02 00:13:08 +00002849 !Op1I->getType()->isFPOrFPVector()) {
Chris Lattner3082c5a2003-02-18 19:28:33 +00002850 // Swap the two operands of the subexpr...
2851 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
2852 Op1I->setOperand(0, IIOp1);
2853 Op1I->setOperand(1, IIOp0);
Misha Brukmanb1c93172005-04-21 23:48:37 +00002854
Chris Lattner3082c5a2003-02-18 19:28:33 +00002855 // Create the new top level add instruction...
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00002856 return BinaryOperator::createAdd(Op0, Op1);
Chris Lattner3082c5a2003-02-18 19:28:33 +00002857 }
2858
2859 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
2860 //
2861 if (Op1I->getOpcode() == Instruction::And &&
2862 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
2863 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
2864
Chris Lattner396dbfe2004-06-09 05:08:07 +00002865 Value *NewNot =
2866 InsertNewInstBefore(BinaryOperator::createNot(OtherOp, "B.not"), I);
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00002867 return BinaryOperator::createAnd(Op0, NewNot);
Chris Lattner3082c5a2003-02-18 19:28:33 +00002868 }
Chris Lattner57c8d992003-02-18 19:57:07 +00002869
Reid Spencer3c514952006-10-16 23:08:08 +00002870 // 0 - (X sdiv C) -> (X sdiv -C)
Reid Spencer7e80b0b2006-10-26 06:15:43 +00002871 if (Op1I->getOpcode() == Instruction::SDiv)
Reid Spencere0fc4df2006-10-20 07:07:24 +00002872 if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
Reid Spencer7e80b0b2006-10-26 06:15:43 +00002873 if (CSI->isNullValue())
Chris Lattner0aee4b72004-10-06 15:08:25 +00002874 if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
Reid Spencer7e80b0b2006-10-26 06:15:43 +00002875 return BinaryOperator::createSDiv(Op1I->getOperand(0),
Chris Lattner0aee4b72004-10-06 15:08:25 +00002876 ConstantExpr::getNeg(DivRHS));
2877
Chris Lattner57c8d992003-02-18 19:57:07 +00002878 // X - X*C --> X * (1-C)
Reid Spencer4fdd96c2005-06-18 17:37:34 +00002879 ConstantInt *C2 = 0;
Chris Lattner8c3e7b92004-11-13 19:50:12 +00002880 if (dyn_castFoldableMul(Op1I, C2) == Op0) {
Misha Brukmanb1c93172005-04-21 23:48:37 +00002881 Constant *CP1 =
Chris Lattner8c3e7b92004-11-13 19:50:12 +00002882 ConstantExpr::getSub(ConstantInt::get(I.getType(), 1), C2);
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00002883 return BinaryOperator::createMul(Op0, CP1);
Chris Lattner57c8d992003-02-18 19:57:07 +00002884 }
Chris Lattnerad3c4952002-05-09 01:29:19 +00002885 }
Chris Lattnera9be4492005-04-07 16:15:25 +00002886 }
Chris Lattner3082c5a2003-02-18 19:28:33 +00002887
Chris Lattner7a002fe2006-12-02 00:13:08 +00002888 if (!Op0->getType()->isFPOrFPVector())
Chris Lattner47060462005-04-07 17:14:51 +00002889 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
2890 if (Op0I->getOpcode() == Instruction::Add) {
Chris Lattner411336f2005-01-19 21:50:18 +00002891 if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
2892 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
2893 else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
2894 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
Chris Lattner47060462005-04-07 17:14:51 +00002895 } else if (Op0I->getOpcode() == Instruction::Sub) {
2896 if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
2897 return BinaryOperator::createNeg(Op0I->getOperand(1), I.getName());
Chris Lattner411336f2005-01-19 21:50:18 +00002898 }
Misha Brukmanb1c93172005-04-21 23:48:37 +00002899
Chris Lattner8c3e7b92004-11-13 19:50:12 +00002900 ConstantInt *C1;
2901 if (Value *X = dyn_castFoldableMul(Op0, C1)) {
2902 if (X == Op1) { // X*C - X --> X * (C-1)
2903 Constant *CP1 = ConstantExpr::getSub(C1, ConstantInt::get(I.getType(),1));
2904 return BinaryOperator::createMul(Op1, CP1);
2905 }
Chris Lattner57c8d992003-02-18 19:57:07 +00002906
Chris Lattner8c3e7b92004-11-13 19:50:12 +00002907 ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
2908 if (X == dyn_castFoldableMul(Op1, C2))
2909 return BinaryOperator::createMul(Op1, ConstantExpr::getSub(C1, C2));
2910 }
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00002911 return 0;
Chris Lattner260ab202002-04-18 17:39:14 +00002912}
2913
Reid Spencer266e42b2006-12-23 06:05:41 +00002914/// isSignBitCheck - Given an exploded icmp instruction, return true if it
Chris Lattnere79e8542004-02-23 06:38:22 +00002915/// really just returns true if the most significant (sign) bit is set.
Reid Spencer266e42b2006-12-23 06:05:41 +00002916static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS) {
2917 switch (pred) {
2918 case ICmpInst::ICMP_SLT:
2919 // True if LHS s< RHS and RHS == 0
2920 return RHS->isNullValue();
2921 case ICmpInst::ICMP_SLE:
2922 // True if LHS s<= RHS and RHS == -1
2923 return RHS->isAllOnesValue();
2924 case ICmpInst::ICMP_UGE:
2925 // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc)
2926 return RHS->getZExtValue() == (1ULL <<
2927 (RHS->getType()->getPrimitiveSizeInBits()-1));
2928 case ICmpInst::ICMP_UGT:
2929 // True if LHS u> RHS and RHS == high-bit-mask - 1
2930 return RHS->getZExtValue() ==
Chris Lattnerd1f46d32005-04-24 06:59:08 +00002931 (1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1))-1;
Reid Spencer266e42b2006-12-23 06:05:41 +00002932 default:
2933 return false;
Chris Lattnere79e8542004-02-23 06:38:22 +00002934 }
Chris Lattnere79e8542004-02-23 06:38:22 +00002935}
2936
Chris Lattner113f4f42002-06-25 16:13:24 +00002937Instruction *InstCombiner::visitMul(BinaryOperator &I) {
Chris Lattnerdcf240a2003-03-10 21:43:22 +00002938 bool Changed = SimplifyCommutative(I);
Chris Lattner3082c5a2003-02-18 19:28:33 +00002939 Value *Op0 = I.getOperand(0);
Chris Lattner260ab202002-04-18 17:39:14 +00002940
Chris Lattner81a7a232004-10-16 18:11:37 +00002941 if (isa<UndefValue>(I.getOperand(1))) // undef * X -> 0
2942 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2943
Chris Lattnere6794492002-08-12 21:17:25 +00002944 // Simplify mul instructions with a constant RHS...
Chris Lattner3082c5a2003-02-18 19:28:33 +00002945 if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
2946 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
Chris Lattnerede3fe02003-08-13 04:18:28 +00002947
2948 // ((X << C1)*C2) == (X * (C2 << C1))
Reid Spencer2341c222007-02-02 02:16:23 +00002949 if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op0))
Chris Lattnerede3fe02003-08-13 04:18:28 +00002950 if (SI->getOpcode() == Instruction::Shl)
2951 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00002952 return BinaryOperator::createMul(SI->getOperand(0),
2953 ConstantExpr::getShl(CI, ShOp));
Misha Brukmanb1c93172005-04-21 23:48:37 +00002954
Chris Lattnercce81be2003-09-11 22:24:54 +00002955 if (CI->isNullValue())
2956 return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
2957 if (CI->equalsInt(1)) // X * 1 == X
2958 return ReplaceInstUsesWith(I, Op0);
2959 if (CI->isAllOnesValue()) // X * -1 == 0 - X
Chris Lattner35236d82003-06-25 17:09:20 +00002960 return BinaryOperator::createNeg(Op0, I.getName());
Chris Lattner31ba1292002-04-29 22:24:47 +00002961
Reid Spencere0fc4df2006-10-20 07:07:24 +00002962 int64_t Val = (int64_t)cast<ConstantInt>(CI)->getZExtValue();
Chris Lattner22d00a82005-08-02 19:16:58 +00002963 if (isPowerOf2_64(Val)) { // Replace X*(2^C) with X << C
2964 uint64_t C = Log2_64(Val);
Reid Spencer0d5f9232007-02-02 14:08:20 +00002965 return BinaryOperator::createShl(Op0,
Reid Spencer2341c222007-02-02 02:16:23 +00002966 ConstantInt::get(Op0->getType(), C));
Chris Lattner22d00a82005-08-02 19:16:58 +00002967 }
Robert Bocchino7b5b86c2004-07-27 21:02:21 +00002968 } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) {
Chris Lattner3082c5a2003-02-18 19:28:33 +00002969 if (Op1F->isNullValue())
2970 return ReplaceInstUsesWith(I, Op1);
Chris Lattner31ba1292002-04-29 22:24:47 +00002971
Chris Lattner3082c5a2003-02-18 19:28:33 +00002972 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
2973 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
2974 if (Op1F->getValue() == 1.0)
2975 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
2976 }
Chris Lattner32c01df2006-03-04 06:04:02 +00002977
2978 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
2979 if (Op0I->getOpcode() == Instruction::Add && Op0I->hasOneUse() &&
2980 isa<ConstantInt>(Op0I->getOperand(1))) {
2981 // Canonicalize (X+C1)*C2 -> X*C2+C1*C2.
2982 Instruction *Add = BinaryOperator::createMul(Op0I->getOperand(0),
2983 Op1, "tmp");
2984 InsertNewInstBefore(Add, I);
2985 Value *C1C2 = ConstantExpr::getMul(Op1,
2986 cast<Constant>(Op0I->getOperand(1)));
2987 return BinaryOperator::createAdd(Add, C1C2);
2988
2989 }
Chris Lattner183b3362004-04-09 19:05:30 +00002990
2991 // Try to fold constant mul into select arguments.
2992 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
Chris Lattner86102b82005-01-01 16:22:27 +00002993 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
Chris Lattner183b3362004-04-09 19:05:30 +00002994 return R;
Chris Lattner6a4adcd2004-09-29 05:07:12 +00002995
2996 if (isa<PHINode>(Op0))
2997 if (Instruction *NV = FoldOpIntoPhi(I))
2998 return NV;
Chris Lattner260ab202002-04-18 17:39:14 +00002999 }
3000
Chris Lattner934a64cf2003-03-10 23:23:04 +00003001 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
3002 if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00003003 return BinaryOperator::createMul(Op0v, Op1v);
Chris Lattner934a64cf2003-03-10 23:23:04 +00003004
Chris Lattner2635b522004-02-23 05:39:21 +00003005 // If one of the operands of the multiply is a cast from a boolean value, then
3006 // we know the bool is either zero or one, so this is a 'masking' multiply.
3007 // See if we can simplify things based on how the boolean was originally
3008 // formed.
3009 CastInst *BoolCast = 0;
Reid Spencer74a528b2006-12-13 18:21:21 +00003010 if (ZExtInst *CI = dyn_cast<ZExtInst>(I.getOperand(0)))
Reid Spencer542964f2007-01-11 18:21:29 +00003011 if (CI->getOperand(0)->getType() == Type::Int1Ty)
Chris Lattner2635b522004-02-23 05:39:21 +00003012 BoolCast = CI;
3013 if (!BoolCast)
Reid Spencer74a528b2006-12-13 18:21:21 +00003014 if (ZExtInst *CI = dyn_cast<ZExtInst>(I.getOperand(1)))
Reid Spencer542964f2007-01-11 18:21:29 +00003015 if (CI->getOperand(0)->getType() == Type::Int1Ty)
Chris Lattner2635b522004-02-23 05:39:21 +00003016 BoolCast = CI;
3017 if (BoolCast) {
Reid Spencer266e42b2006-12-23 06:05:41 +00003018 if (ICmpInst *SCI = dyn_cast<ICmpInst>(BoolCast->getOperand(0))) {
Chris Lattner2635b522004-02-23 05:39:21 +00003019 Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
3020 const Type *SCOpTy = SCIOp0->getType();
3021
Reid Spencer266e42b2006-12-23 06:05:41 +00003022 // If the icmp is true iff the sign bit of X is set, then convert this
Chris Lattnere79e8542004-02-23 06:38:22 +00003023 // multiply into a shift/and combination.
3024 if (isa<ConstantInt>(SCIOp1) &&
Reid Spencer266e42b2006-12-23 06:05:41 +00003025 isSignBitCheck(SCI->getPredicate(), cast<ConstantInt>(SCIOp1))) {
Chris Lattner2635b522004-02-23 05:39:21 +00003026 // Shift the X value right to turn it into "all signbits".
Reid Spencer2341c222007-02-02 02:16:23 +00003027 Constant *Amt = ConstantInt::get(SCIOp0->getType(),
Chris Lattnerd1f46d32005-04-24 06:59:08 +00003028 SCOpTy->getPrimitiveSizeInBits()-1);
Chris Lattnere79e8542004-02-23 06:38:22 +00003029 Value *V =
Reid Spencer2341c222007-02-02 02:16:23 +00003030 InsertNewInstBefore(
3031 BinaryOperator::create(Instruction::AShr, SCIOp0, Amt,
Chris Lattnere79e8542004-02-23 06:38:22 +00003032 BoolCast->getOperand(0)->getName()+
3033 ".mask"), I);
Chris Lattner2635b522004-02-23 05:39:21 +00003034
3035 // If the multiply type is not the same as the source type, sign extend
3036 // or truncate to the multiply type.
Reid Spencer13bc5d72006-12-12 09:18:51 +00003037 if (I.getType() != V->getType()) {
3038 unsigned SrcBits = V->getType()->getPrimitiveSizeInBits();
3039 unsigned DstBits = I.getType()->getPrimitiveSizeInBits();
3040 Instruction::CastOps opcode =
3041 (SrcBits == DstBits ? Instruction::BitCast :
3042 (SrcBits < DstBits ? Instruction::SExt : Instruction::Trunc));
3043 V = InsertCastBefore(opcode, V, I.getType(), I);
3044 }
Misha Brukmanb1c93172005-04-21 23:48:37 +00003045
Chris Lattner2635b522004-02-23 05:39:21 +00003046 Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00003047 return BinaryOperator::createAnd(V, OtherOp);
Chris Lattner2635b522004-02-23 05:39:21 +00003048 }
3049 }
3050 }
3051
Chris Lattner113f4f42002-06-25 16:13:24 +00003052 return Changed ? &I : 0;
Chris Lattner260ab202002-04-18 17:39:14 +00003053}
3054
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003055/// This function implements the transforms on div instructions that work
3056/// regardless of the kind of div instruction it is (udiv, sdiv, or fdiv). It is
3057/// used by the visitors to those instructions.
3058/// @brief Transforms common to all three div instructions
Reid Spencer6c38f0b2006-11-27 01:05:10 +00003059Instruction *InstCombiner::commonDivTransforms(BinaryOperator &I) {
Chris Lattnerbf5b7cf2004-12-12 21:48:58 +00003060 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
Chris Lattner81a7a232004-10-16 18:11:37 +00003061
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003062 // undef / X -> 0
3063 if (isa<UndefValue>(Op0))
Chris Lattnerbf5b7cf2004-12-12 21:48:58 +00003064 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003065
3066 // X / undef -> undef
Chris Lattnerbf5b7cf2004-12-12 21:48:58 +00003067 if (isa<UndefValue>(Op1))
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003068 return ReplaceInstUsesWith(I, Op1);
Chris Lattnerbf5b7cf2004-12-12 21:48:58 +00003069
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003070 // Handle cases involving: div X, (select Cond, Y, Z)
Chris Lattnerd79dc792006-09-09 20:26:32 +00003071 if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
3072 // div X, (Cond ? 0 : Y) -> div X, Y. If the div and the select are in the
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003073 // same basic block, then we replace the select with Y, and the condition
3074 // of the select with false (if the cond value is in the same BB). If the
Chris Lattnerd79dc792006-09-09 20:26:32 +00003075 // select has uses other than the div, this allows them to be simplified
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003076 // also. Note that div X, Y is just as good as div X, 0 (undef)
Chris Lattnerd79dc792006-09-09 20:26:32 +00003077 if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
3078 if (ST->isNullValue()) {
3079 Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0));
3080 if (CondI && CondI->getParent() == I.getParent())
Zhou Sheng75b871f2007-01-11 12:24:14 +00003081 UpdateValueUsesWith(CondI, ConstantInt::getFalse());
Chris Lattnerd79dc792006-09-09 20:26:32 +00003082 else if (I.getParent() != SI->getParent() || SI->hasOneUse())
3083 I.setOperand(1, SI->getOperand(2));
3084 else
3085 UpdateValueUsesWith(SI, SI->getOperand(2));
3086 return &I;
3087 }
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003088
Chris Lattnerd79dc792006-09-09 20:26:32 +00003089 // Likewise for: div X, (Cond ? Y : 0) -> div X, Y
3090 if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
3091 if (ST->isNullValue()) {
3092 Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0));
3093 if (CondI && CondI->getParent() == I.getParent())
Zhou Sheng75b871f2007-01-11 12:24:14 +00003094 UpdateValueUsesWith(CondI, ConstantInt::getTrue());
Chris Lattnerd79dc792006-09-09 20:26:32 +00003095 else if (I.getParent() != SI->getParent() || SI->hasOneUse())
3096 I.setOperand(1, SI->getOperand(1));
3097 else
3098 UpdateValueUsesWith(SI, SI->getOperand(1));
3099 return &I;
3100 }
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003101 }
Chris Lattnerd79dc792006-09-09 20:26:32 +00003102
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003103 return 0;
3104}
Misha Brukmanb1c93172005-04-21 23:48:37 +00003105
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003106/// This function implements the transforms common to both integer division
3107/// instructions (udiv and sdiv). It is called by the visitors to those integer
3108/// division instructions.
3109/// @brief Common integer divide transforms
Reid Spencer6c38f0b2006-11-27 01:05:10 +00003110Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003111 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3112
3113 if (Instruction *Common = commonDivTransforms(I))
3114 return Common;
3115
3116 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
3117 // div X, 1 == X
3118 if (RHS->equalsInt(1))
3119 return ReplaceInstUsesWith(I, Op0);
3120
3121 // (X / C1) / C2 -> X / (C1*C2)
3122 if (Instruction *LHS = dyn_cast<Instruction>(Op0))
3123 if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode())
3124 if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
3125 return BinaryOperator::create(I.getOpcode(), LHS->getOperand(0),
3126 ConstantExpr::getMul(RHS, LHSRHS));
Chris Lattner42362612005-04-08 04:03:26 +00003127 }
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003128
3129 if (!RHS->isNullValue()) { // avoid X udiv 0
3130 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
3131 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3132 return R;
3133 if (isa<PHINode>(Op0))
3134 if (Instruction *NV = FoldOpIntoPhi(I))
3135 return NV;
3136 }
Chris Lattnerd79dc792006-09-09 20:26:32 +00003137 }
Misha Brukmanb1c93172005-04-21 23:48:37 +00003138
Chris Lattner3082c5a2003-02-18 19:28:33 +00003139 // 0 / X == 0, we don't need to preserve faults!
Chris Lattnerbf5b7cf2004-12-12 21:48:58 +00003140 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
Chris Lattner3082c5a2003-02-18 19:28:33 +00003141 if (LHS->equalsInt(0))
3142 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3143
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003144 return 0;
3145}
3146
3147Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
3148 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3149
3150 // Handle the integer div common cases
3151 if (Instruction *Common = commonIDivTransforms(I))
3152 return Common;
3153
3154 // X udiv C^2 -> X >> C
3155 // Check to see if this is an unsigned division with an exact power of 2,
3156 // if so, convert to a right shift.
3157 if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) {
3158 if (uint64_t Val = C->getZExtValue()) // Don't break X / 0
3159 if (isPowerOf2_64(Val)) {
3160 uint64_t ShiftAmt = Log2_64(Val);
Reid Spencer0d5f9232007-02-02 14:08:20 +00003161 return BinaryOperator::createLShr(Op0,
Reid Spencer2341c222007-02-02 02:16:23 +00003162 ConstantInt::get(Op0->getType(), ShiftAmt));
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003163 }
3164 }
3165
3166 // X udiv (C1 << N), where C1 is "1<<C2" --> X >> (N+C2)
Reid Spencer2341c222007-02-02 02:16:23 +00003167 if (BinaryOperator *RHSI = dyn_cast<BinaryOperator>(I.getOperand(1))) {
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003168 if (RHSI->getOpcode() == Instruction::Shl &&
3169 isa<ConstantInt>(RHSI->getOperand(0))) {
3170 uint64_t C1 = cast<ConstantInt>(RHSI->getOperand(0))->getZExtValue();
3171 if (isPowerOf2_64(C1)) {
3172 Value *N = RHSI->getOperand(1);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00003173 const Type *NTy = N->getType();
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003174 if (uint64_t C2 = Log2_64(C1)) {
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003175 Constant *C2V = ConstantInt::get(NTy, C2);
3176 N = InsertNewInstBefore(BinaryOperator::createAdd(N, C2V, "tmp"), I);
Chris Lattner2e90b732006-02-05 07:54:04 +00003177 }
Reid Spencer0d5f9232007-02-02 14:08:20 +00003178 return BinaryOperator::createLShr(Op0, N);
Chris Lattner2e90b732006-02-05 07:54:04 +00003179 }
3180 }
Chris Lattnerdd0c1742005-11-05 07:40:31 +00003181 }
3182
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003183 // udiv X, (Select Cond, C1, C2) --> Select Cond, (shr X, C1), (shr X, C2)
3184 // where C1&C2 are powers of two.
Reid Spencer3939b1a2007-03-05 23:36:13 +00003185 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003186 if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
Reid Spencer3939b1a2007-03-05 23:36:13 +00003187 if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
3188 uint64_t TVA = STO->getZExtValue(), FVA = SFO->getZExtValue();
3189 if (isPowerOf2_64(TVA) && isPowerOf2_64(FVA)) {
3190 // Compute the shift amounts
3191 unsigned TSA = Log2_64(TVA), FSA = Log2_64(FVA);
3192 // Construct the "on true" case of the select
3193 Constant *TC = ConstantInt::get(Op0->getType(), TSA);
3194 Instruction *TSI = BinaryOperator::createLShr(
3195 Op0, TC, SI->getName()+".t");
3196 TSI = InsertNewInstBefore(TSI, I);
3197
3198 // Construct the "on false" case of the select
3199 Constant *FC = ConstantInt::get(Op0->getType(), FSA);
3200 Instruction *FSI = BinaryOperator::createLShr(
3201 Op0, FC, SI->getName()+".f");
3202 FSI = InsertNewInstBefore(FSI, I);
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003203
Reid Spencer3939b1a2007-03-05 23:36:13 +00003204 // construct the select instruction and return it.
3205 return new SelectInst(SI->getOperand(0), TSI, FSI, SI->getName());
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003206 }
Reid Spencer3939b1a2007-03-05 23:36:13 +00003207 }
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00003208 return 0;
3209}
3210
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003211Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
3212 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3213
3214 // Handle the integer div common cases
3215 if (Instruction *Common = commonIDivTransforms(I))
3216 return Common;
3217
3218 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
3219 // sdiv X, -1 == -X
3220 if (RHS->isAllOnesValue())
3221 return BinaryOperator::createNeg(Op0);
3222
3223 // -X/C -> X/-C
3224 if (Value *LHSNeg = dyn_castNegVal(Op0))
3225 return BinaryOperator::createSDiv(LHSNeg, ConstantExpr::getNeg(RHS));
3226 }
3227
3228 // If the sign bits of both operands are zero (i.e. we can prove they are
3229 // unsigned inputs), turn this into a udiv.
Chris Lattner03c49532007-01-15 02:27:26 +00003230 if (I.getType()->isInteger()) {
Reid Spencer7e80b0b2006-10-26 06:15:43 +00003231 uint64_t Mask = 1ULL << (I.getType()->getPrimitiveSizeInBits()-1);
3232 if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
3233 return BinaryOperator::createUDiv(Op0, Op1, I.getName());
3234 }
3235 }
3236
3237 return 0;
3238}
3239
3240Instruction *InstCombiner::visitFDiv(BinaryOperator &I) {
3241 return commonDivTransforms(I);
3242}
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00003243
Chris Lattner85dda9a2006-03-02 06:50:58 +00003244/// GetFactor - If we can prove that the specified value is at least a multiple
3245/// of some factor, return that factor.
3246static Constant *GetFactor(Value *V) {
3247 if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
3248 return CI;
3249
3250 // Unless we can be tricky, we know this is a multiple of 1.
3251 Constant *Result = ConstantInt::get(V->getType(), 1);
3252
3253 Instruction *I = dyn_cast<Instruction>(V);
3254 if (!I) return Result;
3255
3256 if (I->getOpcode() == Instruction::Mul) {
3257 // Handle multiplies by a constant, etc.
3258 return ConstantExpr::getMul(GetFactor(I->getOperand(0)),
3259 GetFactor(I->getOperand(1)));
3260 } else if (I->getOpcode() == Instruction::Shl) {
3261 // (X<<C) -> X * (1 << C)
3262 if (Constant *ShRHS = dyn_cast<Constant>(I->getOperand(1))) {
3263 ShRHS = ConstantExpr::getShl(Result, ShRHS);
3264 return ConstantExpr::getMul(GetFactor(I->getOperand(0)), ShRHS);
3265 }
3266 } else if (I->getOpcode() == Instruction::And) {
3267 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
3268 // X & 0xFFF0 is known to be a multiple of 16.
3269 unsigned Zeros = CountTrailingZeros_64(RHS->getZExtValue());
3270 if (Zeros != V->getType()->getPrimitiveSizeInBits())
3271 return ConstantExpr::getShl(Result,
Reid Spencer2341c222007-02-02 02:16:23 +00003272 ConstantInt::get(Result->getType(), Zeros));
Chris Lattner85dda9a2006-03-02 06:50:58 +00003273 }
Reid Spencer6c38f0b2006-11-27 01:05:10 +00003274 } else if (CastInst *CI = dyn_cast<CastInst>(I)) {
Chris Lattner85dda9a2006-03-02 06:50:58 +00003275 // Only handle int->int casts.
Reid Spencer6c38f0b2006-11-27 01:05:10 +00003276 if (!CI->isIntegerCast())
3277 return Result;
3278 Value *Op = CI->getOperand(0);
3279 return ConstantExpr::getCast(CI->getOpcode(), GetFactor(Op), V->getType());
Chris Lattner85dda9a2006-03-02 06:50:58 +00003280 }
3281 return Result;
3282}
3283
Reid Spencer7eb55b32006-11-02 01:53:59 +00003284/// This function implements the transforms on rem instructions that work
3285/// regardless of the kind of rem instruction it is (urem, srem, or frem). It
3286/// is used by the visitors to those instructions.
3287/// @brief Transforms common to all three rem instructions
3288Instruction *InstCombiner::commonRemTransforms(BinaryOperator &I) {
Chris Lattnerbf5b7cf2004-12-12 21:48:58 +00003289 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
Reid Spencer7eb55b32006-11-02 01:53:59 +00003290
Chris Lattner0de4a8d2006-02-28 05:30:45 +00003291 // 0 % X == 0, we don't need to preserve faults!
3292 if (Constant *LHS = dyn_cast<Constant>(Op0))
3293 if (LHS->isNullValue())
3294 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3295
3296 if (isa<UndefValue>(Op0)) // undef % X -> 0
3297 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3298 if (isa<UndefValue>(Op1))
3299 return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
Reid Spencer7eb55b32006-11-02 01:53:59 +00003300
3301 // Handle cases involving: rem X, (select Cond, Y, Z)
3302 if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
3303 // rem X, (Cond ? 0 : Y) -> rem X, Y. If the rem and the select are in
3304 // the same basic block, then we replace the select with Y, and the
3305 // condition of the select with false (if the cond value is in the same
3306 // BB). If the select has uses other than the div, this allows them to be
3307 // simplified also.
3308 if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
3309 if (ST->isNullValue()) {
3310 Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0));
3311 if (CondI && CondI->getParent() == I.getParent())
Zhou Sheng75b871f2007-01-11 12:24:14 +00003312 UpdateValueUsesWith(CondI, ConstantInt::getFalse());
Reid Spencer7eb55b32006-11-02 01:53:59 +00003313 else if (I.getParent() != SI->getParent() || SI->hasOneUse())
3314 I.setOperand(1, SI->getOperand(2));
3315 else
3316 UpdateValueUsesWith(SI, SI->getOperand(2));
Chris Lattner7fd5f072004-07-06 07:01:22 +00003317 return &I;
3318 }
Reid Spencer7eb55b32006-11-02 01:53:59 +00003319 // Likewise for: rem X, (Cond ? Y : 0) -> rem X, Y
3320 if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
3321 if (ST->isNullValue()) {
3322 Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0));
3323 if (CondI && CondI->getParent() == I.getParent())
Zhou Sheng75b871f2007-01-11 12:24:14 +00003324 UpdateValueUsesWith(CondI, ConstantInt::getTrue());
Reid Spencer7eb55b32006-11-02 01:53:59 +00003325 else if (I.getParent() != SI->getParent() || SI->hasOneUse())
3326 I.setOperand(1, SI->getOperand(1));
3327 else
3328 UpdateValueUsesWith(SI, SI->getOperand(1));
3329 return &I;
3330 }
Chris Lattnere9ff0ea2005-11-05 07:28:37 +00003331 }
Chris Lattner7fd5f072004-07-06 07:01:22 +00003332
Reid Spencer7eb55b32006-11-02 01:53:59 +00003333 return 0;
3334}
3335
3336/// This function implements the transforms common to both integer remainder
3337/// instructions (urem and srem). It is called by the visitors to those integer
3338/// remainder instructions.
3339/// @brief Common integer remainder transforms
3340Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) {
3341 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3342
3343 if (Instruction *common = commonRemTransforms(I))
3344 return common;
3345
Chris Lattnerbf5b7cf2004-12-12 21:48:58 +00003346 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
Chris Lattner0de4a8d2006-02-28 05:30:45 +00003347 // X % 0 == undef, we don't need to preserve faults!
3348 if (RHS->equalsInt(0))
3349 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
3350
Chris Lattner3082c5a2003-02-18 19:28:33 +00003351 if (RHS->equalsInt(1)) // X % 1 == 0
3352 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3353
Chris Lattnerb70f1412006-02-28 05:49:21 +00003354 if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) {
3355 if (SelectInst *SI = dyn_cast<SelectInst>(Op0I)) {
3356 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3357 return R;
3358 } else if (isa<PHINode>(Op0I)) {
3359 if (Instruction *NV = FoldOpIntoPhi(I))
3360 return NV;
Chris Lattnerb70f1412006-02-28 05:49:21 +00003361 }
Reid Spencer7eb55b32006-11-02 01:53:59 +00003362 // (X * C1) % C2 --> 0 iff C1 % C2 == 0
3363 if (ConstantExpr::getSRem(GetFactor(Op0I), RHS)->isNullValue())
Chris Lattner85dda9a2006-03-02 06:50:58 +00003364 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
Chris Lattnerb70f1412006-02-28 05:49:21 +00003365 }
Chris Lattner3082c5a2003-02-18 19:28:33 +00003366 }
3367
Reid Spencer7eb55b32006-11-02 01:53:59 +00003368 return 0;
3369}
3370
3371Instruction *InstCombiner::visitURem(BinaryOperator &I) {
3372 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3373
3374 if (Instruction *common = commonIRemTransforms(I))
3375 return common;
3376
3377 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
3378 // X urem C^2 -> X and C
3379 // Check to see if this is an unsigned remainder with an exact power of 2,
3380 // if so, convert to a bitwise and.
3381 if (ConstantInt *C = dyn_cast<ConstantInt>(RHS))
3382 if (isPowerOf2_64(C->getZExtValue()))
3383 return BinaryOperator::createAnd(Op0, SubOne(C));
3384 }
3385
Chris Lattner2e90b732006-02-05 07:54:04 +00003386 if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) {
Reid Spencer7eb55b32006-11-02 01:53:59 +00003387 // Turn A % (C << N), where C is 2^k, into A & ((C << N)-1)
3388 if (RHSI->getOpcode() == Instruction::Shl &&
3389 isa<ConstantInt>(RHSI->getOperand(0))) {
Reid Spencere0fc4df2006-10-20 07:07:24 +00003390 unsigned C1 = cast<ConstantInt>(RHSI->getOperand(0))->getZExtValue();
Chris Lattner2e90b732006-02-05 07:54:04 +00003391 if (isPowerOf2_64(C1)) {
3392 Constant *N1 = ConstantInt::getAllOnesValue(I.getType());
3393 Value *Add = InsertNewInstBefore(BinaryOperator::createAdd(RHSI, N1,
3394 "tmp"), I);
3395 return BinaryOperator::createAnd(Op0, Add);
3396 }
3397 }
Reid Spencer7eb55b32006-11-02 01:53:59 +00003398 }
Chris Lattnerd79dc792006-09-09 20:26:32 +00003399
Reid Spencer7eb55b32006-11-02 01:53:59 +00003400 // urem X, (select Cond, 2^C1, 2^C2) --> select Cond, (and X, C1), (and X, C2)
3401 // where C1&C2 are powers of two.
3402 if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
3403 if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
3404 if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
3405 // STO == 0 and SFO == 0 handled above.
3406 if (isPowerOf2_64(STO->getZExtValue()) &&
3407 isPowerOf2_64(SFO->getZExtValue())) {
3408 Value *TrueAnd = InsertNewInstBefore(
3409 BinaryOperator::createAnd(Op0, SubOne(STO), SI->getName()+".t"), I);
3410 Value *FalseAnd = InsertNewInstBefore(
3411 BinaryOperator::createAnd(Op0, SubOne(SFO), SI->getName()+".f"), I);
3412 return new SelectInst(SI->getOperand(0), TrueAnd, FalseAnd);
3413 }
3414 }
Chris Lattner2e90b732006-02-05 07:54:04 +00003415 }
3416
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00003417 return 0;
3418}
3419
Reid Spencer7eb55b32006-11-02 01:53:59 +00003420Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
3421 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3422
3423 if (Instruction *common = commonIRemTransforms(I))
3424 return common;
3425
3426 if (Value *RHSNeg = dyn_castNegVal(Op1))
3427 if (!isa<ConstantInt>(RHSNeg) ||
3428 cast<ConstantInt>(RHSNeg)->getSExtValue() > 0) {
3429 // X % -Y -> X % Y
3430 AddUsesToWorkList(I);
3431 I.setOperand(1, RHSNeg);
3432 return &I;
3433 }
3434
3435 // If the top bits of both operands are zero (i.e. we can prove they are
3436 // unsigned inputs), turn this into a urem.
3437 uint64_t Mask = 1ULL << (I.getType()->getPrimitiveSizeInBits()-1);
3438 if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
3439 // X srem Y -> X urem Y, iff X and Y don't have sign bit set
3440 return BinaryOperator::createURem(Op0, Op1, I.getName());
3441 }
3442
3443 return 0;
3444}
3445
3446Instruction *InstCombiner::visitFRem(BinaryOperator &I) {
Reid Spencer7eb55b32006-11-02 01:53:59 +00003447 return commonRemTransforms(I);
3448}
3449
Chris Lattner6d14f2a2002-08-09 23:47:40 +00003450// isMaxValueMinusOne - return true if this is Max-1
Reid Spencer266e42b2006-12-23 06:05:41 +00003451static bool isMaxValueMinusOne(const ConstantInt *C, bool isSigned) {
3452 if (isSigned) {
3453 // Calculate 0111111111..11111
3454 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
3455 int64_t Val = INT64_MAX; // All ones
3456 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
3457 return C->getSExtValue() == Val-1;
3458 }
Reid Spencera94d3942007-01-19 21:13:56 +00003459 return C->getZExtValue() == C->getType()->getBitMask()-1;
Chris Lattner6d14f2a2002-08-09 23:47:40 +00003460}
3461
3462// isMinValuePlusOne - return true if this is Min+1
Reid Spencer266e42b2006-12-23 06:05:41 +00003463static bool isMinValuePlusOne(const ConstantInt *C, bool isSigned) {
3464 if (isSigned) {
3465 // Calculate 1111111111000000000000
3466 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
3467 int64_t Val = -1; // All ones
3468 Val <<= TypeBits-1; // Shift over to the right spot
3469 return C->getSExtValue() == Val+1;
3470 }
3471 return C->getZExtValue() == 1; // unsigned
Chris Lattner6d14f2a2002-08-09 23:47:40 +00003472}
3473
Chris Lattner35167c32004-06-09 07:59:58 +00003474// isOneBitSet - Return true if there is exactly one bit set in the specified
3475// constant.
3476static bool isOneBitSet(const ConstantInt *CI) {
Reid Spencer129a8672007-03-19 21:04:43 +00003477 return CI->getValue().countPopulation() == 1;
Chris Lattner35167c32004-06-09 07:59:58 +00003478}
3479
Chris Lattner8fc5af42004-09-23 21:46:38 +00003480#if 0 // Currently unused
3481// isLowOnes - Return true if the constant is of the form 0+1+.
3482static bool isLowOnes(const ConstantInt *CI) {
Reid Spencere0fc4df2006-10-20 07:07:24 +00003483 uint64_t V = CI->getZExtValue();
Chris Lattner8fc5af42004-09-23 21:46:38 +00003484
3485 // There won't be bits set in parts that the type doesn't contain.
Reid Spencere0fc4df2006-10-20 07:07:24 +00003486 V &= ConstantInt::getAllOnesValue(CI->getType())->getZExtValue();
Chris Lattner8fc5af42004-09-23 21:46:38 +00003487
3488 uint64_t U = V+1; // If it is low ones, this should be a power of two.
3489 return U && V && (U & V) == 0;
3490}
3491#endif
3492
3493// isHighOnes - Return true if the constant is of the form 1+0+.
3494// This is the same as lowones(~X).
3495static bool isHighOnes(const ConstantInt *CI) {
Reid Spencere0fc4df2006-10-20 07:07:24 +00003496 uint64_t V = ~CI->getZExtValue();
Chris Lattner2c14cf72005-08-07 07:03:10 +00003497 if (~V == 0) return false; // 0's does not match "1+"
Chris Lattner8fc5af42004-09-23 21:46:38 +00003498
3499 // There won't be bits set in parts that the type doesn't contain.
Reid Spencere0fc4df2006-10-20 07:07:24 +00003500 V &= ConstantInt::getAllOnesValue(CI->getType())->getZExtValue();
Chris Lattner8fc5af42004-09-23 21:46:38 +00003501
3502 uint64_t U = V+1; // If it is low ones, this should be a power of two.
3503 return U && V && (U & V) == 0;
3504}
3505
Reid Spencer266e42b2006-12-23 06:05:41 +00003506/// getICmpCode - Encode a icmp predicate into a three bit mask. These bits
Chris Lattner3ac7c262003-08-13 20:16:26 +00003507/// are carefully arranged to allow folding of expressions such as:
3508///
3509/// (A < B) | (A > B) --> (A != B)
3510///
Reid Spencer266e42b2006-12-23 06:05:41 +00003511/// Note that this is only valid if the first and second predicates have the
3512/// same sign. Is illegal to do: (A u< B) | (A s> B)
Chris Lattner3ac7c262003-08-13 20:16:26 +00003513///
Reid Spencer266e42b2006-12-23 06:05:41 +00003514/// Three bits are used to represent the condition, as follows:
3515/// 0 A > B
3516/// 1 A == B
3517/// 2 A < B
3518///
3519/// <=> Value Definition
3520/// 000 0 Always false
3521/// 001 1 A > B
3522/// 010 2 A == B
3523/// 011 3 A >= B
3524/// 100 4 A < B
3525/// 101 5 A != B
3526/// 110 6 A <= B
3527/// 111 7 Always true
3528///
3529static unsigned getICmpCode(const ICmpInst *ICI) {
3530 switch (ICI->getPredicate()) {
Chris Lattner3ac7c262003-08-13 20:16:26 +00003531 // False -> 0
Reid Spencer266e42b2006-12-23 06:05:41 +00003532 case ICmpInst::ICMP_UGT: return 1; // 001
3533 case ICmpInst::ICMP_SGT: return 1; // 001
3534 case ICmpInst::ICMP_EQ: return 2; // 010
3535 case ICmpInst::ICMP_UGE: return 3; // 011
3536 case ICmpInst::ICMP_SGE: return 3; // 011
3537 case ICmpInst::ICMP_ULT: return 4; // 100
3538 case ICmpInst::ICMP_SLT: return 4; // 100
3539 case ICmpInst::ICMP_NE: return 5; // 101
3540 case ICmpInst::ICMP_ULE: return 6; // 110
3541 case ICmpInst::ICMP_SLE: return 6; // 110
Chris Lattner3ac7c262003-08-13 20:16:26 +00003542 // True -> 7
3543 default:
Reid Spencer266e42b2006-12-23 06:05:41 +00003544 assert(0 && "Invalid ICmp predicate!");
Chris Lattner3ac7c262003-08-13 20:16:26 +00003545 return 0;
3546 }
3547}
3548
Reid Spencer266e42b2006-12-23 06:05:41 +00003549/// getICmpValue - This is the complement of getICmpCode, which turns an
3550/// opcode and two operands into either a constant true or false, or a brand
3551/// new /// ICmp instruction. The sign is passed in to determine which kind
3552/// of predicate to use in new icmp instructions.
3553static Value *getICmpValue(bool sign, unsigned code, Value *LHS, Value *RHS) {
3554 switch (code) {
3555 default: assert(0 && "Illegal ICmp code!");
Zhou Sheng75b871f2007-01-11 12:24:14 +00003556 case 0: return ConstantInt::getFalse();
Reid Spencer266e42b2006-12-23 06:05:41 +00003557 case 1:
3558 if (sign)
3559 return new ICmpInst(ICmpInst::ICMP_SGT, LHS, RHS);
3560 else
3561 return new ICmpInst(ICmpInst::ICMP_UGT, LHS, RHS);
3562 case 2: return new ICmpInst(ICmpInst::ICMP_EQ, LHS, RHS);
3563 case 3:
3564 if (sign)
3565 return new ICmpInst(ICmpInst::ICMP_SGE, LHS, RHS);
3566 else
3567 return new ICmpInst(ICmpInst::ICMP_UGE, LHS, RHS);
3568 case 4:
3569 if (sign)
3570 return new ICmpInst(ICmpInst::ICMP_SLT, LHS, RHS);
3571 else
3572 return new ICmpInst(ICmpInst::ICMP_ULT, LHS, RHS);
3573 case 5: return new ICmpInst(ICmpInst::ICMP_NE, LHS, RHS);
3574 case 6:
3575 if (sign)
3576 return new ICmpInst(ICmpInst::ICMP_SLE, LHS, RHS);
3577 else
3578 return new ICmpInst(ICmpInst::ICMP_ULE, LHS, RHS);
Zhou Sheng75b871f2007-01-11 12:24:14 +00003579 case 7: return ConstantInt::getTrue();
Chris Lattner3ac7c262003-08-13 20:16:26 +00003580 }
3581}
3582
Reid Spencer266e42b2006-12-23 06:05:41 +00003583static bool PredicatesFoldable(ICmpInst::Predicate p1, ICmpInst::Predicate p2) {
3584 return (ICmpInst::isSignedPredicate(p1) == ICmpInst::isSignedPredicate(p2)) ||
3585 (ICmpInst::isSignedPredicate(p1) &&
3586 (p2 == ICmpInst::ICMP_EQ || p2 == ICmpInst::ICMP_NE)) ||
3587 (ICmpInst::isSignedPredicate(p2) &&
3588 (p1 == ICmpInst::ICMP_EQ || p1 == ICmpInst::ICMP_NE));
3589}
3590
3591namespace {
3592// FoldICmpLogical - Implements (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
3593struct FoldICmpLogical {
Chris Lattner3ac7c262003-08-13 20:16:26 +00003594 InstCombiner &IC;
3595 Value *LHS, *RHS;
Reid Spencer266e42b2006-12-23 06:05:41 +00003596 ICmpInst::Predicate pred;
3597 FoldICmpLogical(InstCombiner &ic, ICmpInst *ICI)
3598 : IC(ic), LHS(ICI->getOperand(0)), RHS(ICI->getOperand(1)),
3599 pred(ICI->getPredicate()) {}
Chris Lattner3ac7c262003-08-13 20:16:26 +00003600 bool shouldApply(Value *V) const {
Reid Spencer266e42b2006-12-23 06:05:41 +00003601 if (ICmpInst *ICI = dyn_cast<ICmpInst>(V))
3602 if (PredicatesFoldable(pred, ICI->getPredicate()))
3603 return (ICI->getOperand(0) == LHS && ICI->getOperand(1) == RHS ||
3604 ICI->getOperand(0) == RHS && ICI->getOperand(1) == LHS);
Chris Lattner3ac7c262003-08-13 20:16:26 +00003605 return false;
3606 }
Reid Spencer266e42b2006-12-23 06:05:41 +00003607 Instruction *apply(Instruction &Log) const {
3608 ICmpInst *ICI = cast<ICmpInst>(Log.getOperand(0));
3609 if (ICI->getOperand(0) != LHS) {
3610 assert(ICI->getOperand(1) == LHS);
3611 ICI->swapOperands(); // Swap the LHS and RHS of the ICmp
Chris Lattner3ac7c262003-08-13 20:16:26 +00003612 }
3613
Chris Lattnerd1bce952007-03-13 14:27:42 +00003614 ICmpInst *RHSICI = cast<ICmpInst>(Log.getOperand(1));
Reid Spencer266e42b2006-12-23 06:05:41 +00003615 unsigned LHSCode = getICmpCode(ICI);
Chris Lattnerd1bce952007-03-13 14:27:42 +00003616 unsigned RHSCode = getICmpCode(RHSICI);
Chris Lattner3ac7c262003-08-13 20:16:26 +00003617 unsigned Code;
3618 switch (Log.getOpcode()) {
3619 case Instruction::And: Code = LHSCode & RHSCode; break;
3620 case Instruction::Or: Code = LHSCode | RHSCode; break;
3621 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
Chris Lattner2caaaba2003-09-22 20:33:34 +00003622 default: assert(0 && "Illegal logical opcode!"); return 0;
Chris Lattner3ac7c262003-08-13 20:16:26 +00003623 }
3624
Chris Lattnerd1bce952007-03-13 14:27:42 +00003625 bool isSigned = ICmpInst::isSignedPredicate(RHSICI->getPredicate()) ||
3626 ICmpInst::isSignedPredicate(ICI->getPredicate());
3627
3628 Value *RV = getICmpValue(isSigned, Code, LHS, RHS);
Chris Lattner3ac7c262003-08-13 20:16:26 +00003629 if (Instruction *I = dyn_cast<Instruction>(RV))
3630 return I;
3631 // Otherwise, it's a constant boolean value...
3632 return IC.ReplaceInstUsesWith(Log, RV);
3633 }
3634};
Chris Lattnere3a63d12006-11-15 04:53:24 +00003635} // end anonymous namespace
Chris Lattner3ac7c262003-08-13 20:16:26 +00003636
Chris Lattnerba1cb382003-09-19 17:17:26 +00003637// OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
3638// the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
Reid Spencer2341c222007-02-02 02:16:23 +00003639// guaranteed to be a binary operator.
Chris Lattnerba1cb382003-09-19 17:17:26 +00003640Instruction *InstCombiner::OptAndOp(Instruction *Op,
Zhou Sheng75b871f2007-01-11 12:24:14 +00003641 ConstantInt *OpRHS,
3642 ConstantInt *AndRHS,
Chris Lattnerba1cb382003-09-19 17:17:26 +00003643 BinaryOperator &TheAnd) {
3644 Value *X = Op->getOperand(0);
Chris Lattnerfcf21a72004-01-12 19:47:05 +00003645 Constant *Together = 0;
Reid Spencer2341c222007-02-02 02:16:23 +00003646 if (!Op->isShift())
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00003647 Together = ConstantExpr::getAnd(AndRHS, OpRHS);
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00003648
Chris Lattnerba1cb382003-09-19 17:17:26 +00003649 switch (Op->getOpcode()) {
3650 case Instruction::Xor:
Chris Lattner86102b82005-01-01 16:22:27 +00003651 if (Op->hasOneUse()) {
Chris Lattnerba1cb382003-09-19 17:17:26 +00003652 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
Chris Lattner6e0123b2007-02-11 01:23:03 +00003653 Instruction *And = BinaryOperator::createAnd(X, AndRHS);
Chris Lattnerba1cb382003-09-19 17:17:26 +00003654 InsertNewInstBefore(And, TheAnd);
Chris Lattner6e0123b2007-02-11 01:23:03 +00003655 And->takeName(Op);
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00003656 return BinaryOperator::createXor(And, Together);
Chris Lattnerba1cb382003-09-19 17:17:26 +00003657 }
3658 break;
3659 case Instruction::Or:
Chris Lattner86102b82005-01-01 16:22:27 +00003660 if (Together == AndRHS) // (X | C) & C --> C
3661 return ReplaceInstUsesWith(TheAnd, AndRHS);
Misha Brukmanb1c93172005-04-21 23:48:37 +00003662
Chris Lattner86102b82005-01-01 16:22:27 +00003663 if (Op->hasOneUse() && Together != OpRHS) {
3664 // (X | C1) & C2 --> (X | (C1&C2)) & C2
Chris Lattner6e0123b2007-02-11 01:23:03 +00003665 Instruction *Or = BinaryOperator::createOr(X, Together);
Chris Lattner86102b82005-01-01 16:22:27 +00003666 InsertNewInstBefore(Or, TheAnd);
Chris Lattner6e0123b2007-02-11 01:23:03 +00003667 Or->takeName(Op);
Chris Lattner86102b82005-01-01 16:22:27 +00003668 return BinaryOperator::createAnd(Or, AndRHS);
Chris Lattnerba1cb382003-09-19 17:17:26 +00003669 }
3670 break;
3671 case Instruction::Add:
Chris Lattnerf95d9b92003-10-15 16:48:29 +00003672 if (Op->hasOneUse()) {
Chris Lattnerba1cb382003-09-19 17:17:26 +00003673 // Adding a one to a single bit bit-field should be turned into an XOR
3674 // of the bit. First thing to check is to see if this AND is with a
3675 // single bit constant.
Reid Spencere0fc4df2006-10-20 07:07:24 +00003676 uint64_t AndRHSV = cast<ConstantInt>(AndRHS)->getZExtValue();
Chris Lattnerba1cb382003-09-19 17:17:26 +00003677
3678 // Clear bits that are not part of the constant.
Reid Spencera94d3942007-01-19 21:13:56 +00003679 AndRHSV &= AndRHS->getType()->getBitMask();
Chris Lattnerba1cb382003-09-19 17:17:26 +00003680
3681 // If there is only one bit set...
Chris Lattner35167c32004-06-09 07:59:58 +00003682 if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
Chris Lattnerba1cb382003-09-19 17:17:26 +00003683 // Ok, at this point, we know that we are masking the result of the
3684 // ADD down to exactly one bit. If the constant we are adding has
3685 // no bits set below this bit, then we can eliminate the ADD.
Reid Spencere0fc4df2006-10-20 07:07:24 +00003686 uint64_t AddRHS = cast<ConstantInt>(OpRHS)->getZExtValue();
Misha Brukmanb1c93172005-04-21 23:48:37 +00003687
Chris Lattnerba1cb382003-09-19 17:17:26 +00003688 // Check to see if any bits below the one bit set in AndRHSV are set.
3689 if ((AddRHS & (AndRHSV-1)) == 0) {
3690 // If not, the only thing that can effect the output of the AND is
3691 // the bit specified by AndRHSV. If that bit is set, the effect of
3692 // the XOR is to toggle the bit. If it is clear, then the ADD has
3693 // no effect.
3694 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
3695 TheAnd.setOperand(0, X);
3696 return &TheAnd;
3697 } else {
Chris Lattnerba1cb382003-09-19 17:17:26 +00003698 // Pull the XOR out of the AND.
Chris Lattner6e0123b2007-02-11 01:23:03 +00003699 Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS);
Chris Lattnerba1cb382003-09-19 17:17:26 +00003700 InsertNewInstBefore(NewAnd, TheAnd);
Chris Lattner6e0123b2007-02-11 01:23:03 +00003701 NewAnd->takeName(Op);
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00003702 return BinaryOperator::createXor(NewAnd, AndRHS);
Chris Lattnerba1cb382003-09-19 17:17:26 +00003703 }
3704 }
3705 }
3706 }
3707 break;
Chris Lattner2da29172003-09-19 19:05:02 +00003708
3709 case Instruction::Shl: {
3710 // We know that the AND will not produce any of the bits shifted in, so if
3711 // the anded constant includes them, clear them now!
3712 //
Zhou Sheng75b871f2007-01-11 12:24:14 +00003713 Constant *AllOne = ConstantInt::getAllOnesValue(AndRHS->getType());
Chris Lattner7e794272004-09-24 15:21:34 +00003714 Constant *ShlMask = ConstantExpr::getShl(AllOne, OpRHS);
3715 Constant *CI = ConstantExpr::getAnd(AndRHS, ShlMask);
Misha Brukmanb1c93172005-04-21 23:48:37 +00003716
Chris Lattner7e794272004-09-24 15:21:34 +00003717 if (CI == ShlMask) { // Masking out bits that the shift already masks
3718 return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
3719 } else if (CI != AndRHS) { // Reducing bits set in and.
Chris Lattner2da29172003-09-19 19:05:02 +00003720 TheAnd.setOperand(1, CI);
3721 return &TheAnd;
3722 }
3723 break;
Misha Brukmanb1c93172005-04-21 23:48:37 +00003724 }
Reid Spencerfdff9382006-11-08 06:47:33 +00003725 case Instruction::LShr:
3726 {
Chris Lattner2da29172003-09-19 19:05:02 +00003727 // We know that the AND will not produce any of the bits shifted in, so if
3728 // the anded constant includes them, clear them now! This only applies to
3729 // unsigned shifts, because a signed shr may bring in set bits!
3730 //
Zhou Sheng75b871f2007-01-11 12:24:14 +00003731 Constant *AllOne = ConstantInt::getAllOnesValue(AndRHS->getType());
Reid Spencerfdff9382006-11-08 06:47:33 +00003732 Constant *ShrMask = ConstantExpr::getLShr(AllOne, OpRHS);
3733 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
Chris Lattner7e794272004-09-24 15:21:34 +00003734
Reid Spencerfdff9382006-11-08 06:47:33 +00003735 if (CI == ShrMask) { // Masking out bits that the shift already masks.
3736 return ReplaceInstUsesWith(TheAnd, Op);
3737 } else if (CI != AndRHS) {
3738 TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
3739 return &TheAnd;
3740 }
3741 break;
3742 }
3743 case Instruction::AShr:
3744 // Signed shr.
3745 // See if this is shifting in some sign extension, then masking it out
3746 // with an and.
3747 if (Op->hasOneUse()) {
Zhou Sheng75b871f2007-01-11 12:24:14 +00003748 Constant *AllOne = ConstantInt::getAllOnesValue(AndRHS->getType());
Reid Spencerfdff9382006-11-08 06:47:33 +00003749 Constant *ShrMask = ConstantExpr::getLShr(AllOne, OpRHS);
Reid Spencer2a499b02006-12-13 17:19:09 +00003750 Constant *C = ConstantExpr::getAnd(AndRHS, ShrMask);
3751 if (C == AndRHS) { // Masking out bits shifted in.
Reid Spencer13bc5d72006-12-12 09:18:51 +00003752 // (Val ashr C1) & C2 -> (Val lshr C1) & C2
Reid Spencerfdff9382006-11-08 06:47:33 +00003753 // Make the argument unsigned.
3754 Value *ShVal = Op->getOperand(0);
Reid Spencer2341c222007-02-02 02:16:23 +00003755 ShVal = InsertNewInstBefore(
Reid Spencer0d5f9232007-02-02 14:08:20 +00003756 BinaryOperator::createLShr(ShVal, OpRHS,
Reid Spencer2341c222007-02-02 02:16:23 +00003757 Op->getName()), TheAnd);
Reid Spencer2a499b02006-12-13 17:19:09 +00003758 return BinaryOperator::createAnd(ShVal, AndRHS, TheAnd.getName());
Chris Lattner7e794272004-09-24 15:21:34 +00003759 }
Chris Lattner2da29172003-09-19 19:05:02 +00003760 }
3761 break;
Chris Lattnerba1cb382003-09-19 17:17:26 +00003762 }
3763 return 0;
3764}
3765
Chris Lattner6d14f2a2002-08-09 23:47:40 +00003766
Chris Lattner6862fbd2004-09-29 17:40:11 +00003767/// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
3768/// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
Reid Spencer266e42b2006-12-23 06:05:41 +00003769/// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. isSigned indicates
3770/// whether to treat the V, Lo and HI as signed or not. IB is the location to
Chris Lattner6862fbd2004-09-29 17:40:11 +00003771/// insert new instructions.
3772Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
Reid Spencer266e42b2006-12-23 06:05:41 +00003773 bool isSigned, bool Inside,
3774 Instruction &IB) {
Zhou Sheng75b871f2007-01-11 12:24:14 +00003775 assert(cast<ConstantInt>(ConstantExpr::getICmp((isSigned ?
Reid Spencercddc9df2007-01-12 04:24:46 +00003776 ICmpInst::ICMP_SLE:ICmpInst::ICMP_ULE), Lo, Hi))->getZExtValue() &&
Chris Lattner6862fbd2004-09-29 17:40:11 +00003777 "Lo is not <= Hi in range emission code!");
Reid Spencer266e42b2006-12-23 06:05:41 +00003778
Chris Lattner6862fbd2004-09-29 17:40:11 +00003779 if (Inside) {
3780 if (Lo == Hi) // Trivially false.
Reid Spencer266e42b2006-12-23 06:05:41 +00003781 return new ICmpInst(ICmpInst::ICMP_NE, V, V);
Misha Brukmanb1c93172005-04-21 23:48:37 +00003782
Reid Spencer266e42b2006-12-23 06:05:41 +00003783 // V >= Min && V < Hi --> V < Hi
Zhou Sheng75b871f2007-01-11 12:24:14 +00003784 if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
Reid Spencer266e42b2006-12-23 06:05:41 +00003785 ICmpInst::Predicate pred = (isSigned ?
3786 ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT);
3787 return new ICmpInst(pred, V, Hi);
3788 }
3789
3790 // Emit V-Lo <u Hi-Lo
3791 Constant *NegLo = ConstantExpr::getNeg(Lo);
3792 Instruction *Add = BinaryOperator::createAdd(V, NegLo, V->getName()+".off");
Chris Lattner6862fbd2004-09-29 17:40:11 +00003793 InsertNewInstBefore(Add, IB);
Reid Spencer266e42b2006-12-23 06:05:41 +00003794 Constant *UpperBound = ConstantExpr::getAdd(NegLo, Hi);
3795 return new ICmpInst(ICmpInst::ICMP_ULT, Add, UpperBound);
Chris Lattner6862fbd2004-09-29 17:40:11 +00003796 }
3797
3798 if (Lo == Hi) // Trivially true.
Reid Spencer266e42b2006-12-23 06:05:41 +00003799 return new ICmpInst(ICmpInst::ICMP_EQ, V, V);
Chris Lattner6862fbd2004-09-29 17:40:11 +00003800
Reid Spencer266e42b2006-12-23 06:05:41 +00003801 // V < Min || V >= Hi ->'V > Hi-1'
Chris Lattner6862fbd2004-09-29 17:40:11 +00003802 Hi = SubOne(cast<ConstantInt>(Hi));
Zhou Sheng75b871f2007-01-11 12:24:14 +00003803 if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
Reid Spencer266e42b2006-12-23 06:05:41 +00003804 ICmpInst::Predicate pred = (isSigned ?
3805 ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT);
3806 return new ICmpInst(pred, V, Hi);
3807 }
Reid Spencere0fc4df2006-10-20 07:07:24 +00003808
Reid Spencer266e42b2006-12-23 06:05:41 +00003809 // Emit V-Lo > Hi-1-Lo
3810 Constant *NegLo = ConstantExpr::getNeg(Lo);
3811 Instruction *Add = BinaryOperator::createAdd(V, NegLo, V->getName()+".off");
Chris Lattner6862fbd2004-09-29 17:40:11 +00003812 InsertNewInstBefore(Add, IB);
Reid Spencer266e42b2006-12-23 06:05:41 +00003813 Constant *LowerBound = ConstantExpr::getAdd(NegLo, Hi);
3814 return new ICmpInst(ICmpInst::ICMP_UGT, Add, LowerBound);
Chris Lattner6862fbd2004-09-29 17:40:11 +00003815}
3816
Chris Lattnerb4b25302005-09-18 07:22:02 +00003817// isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with
3818// any number of 0s on either side. The 1s are allowed to wrap from LSB to
3819// MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is
3820// not, since all 1s are not contiguous.
Zhou Sheng75b871f2007-01-11 12:24:14 +00003821static bool isRunOfOnes(ConstantInt *Val, unsigned &MB, unsigned &ME) {
Reid Spencere0fc4df2006-10-20 07:07:24 +00003822 uint64_t V = Val->getZExtValue();
Chris Lattnerb4b25302005-09-18 07:22:02 +00003823 if (!isShiftedMask_64(V)) return false;
3824
3825 // look for the first zero bit after the run of ones
3826 MB = 64-CountLeadingZeros_64((V - 1) ^ V);
3827 // look for the first non-zero bit
3828 ME = 64-CountLeadingZeros_64(V);
3829 return true;
3830}
3831
3832
3833
3834/// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask,
3835/// where isSub determines whether the operator is a sub. If we can fold one of
3836/// the following xforms:
Chris Lattneraf517572005-09-18 04:24:45 +00003837///
3838/// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
3839/// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
3840/// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
3841///
3842/// return (A +/- B).
3843///
3844Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
Zhou Sheng75b871f2007-01-11 12:24:14 +00003845 ConstantInt *Mask, bool isSub,
Chris Lattneraf517572005-09-18 04:24:45 +00003846 Instruction &I) {
3847 Instruction *LHSI = dyn_cast<Instruction>(LHS);
3848 if (!LHSI || LHSI->getNumOperands() != 2 ||
3849 !isa<ConstantInt>(LHSI->getOperand(1))) return 0;
3850
3851 ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
3852
3853 switch (LHSI->getOpcode()) {
3854 default: return 0;
3855 case Instruction::And:
Chris Lattnerb4b25302005-09-18 07:22:02 +00003856 if (ConstantExpr::getAnd(N, Mask) == Mask) {
3857 // If the AndRHS is a power of two minus one (0+1+), this is simple.
Reid Spencere0fc4df2006-10-20 07:07:24 +00003858 if ((Mask->getZExtValue() & Mask->getZExtValue()+1) == 0)
Chris Lattnerb4b25302005-09-18 07:22:02 +00003859 break;
3860
3861 // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
3862 // part, we don't need any explicit masks to take them out of A. If that
3863 // is all N is, ignore it.
3864 unsigned MB, ME;
3865 if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
Reid Spencera94d3942007-01-19 21:13:56 +00003866 uint64_t Mask = cast<IntegerType>(RHS->getType())->getBitMask();
Chris Lattnerc3ebf402006-02-07 07:27:52 +00003867 Mask >>= 64-MB+1;
3868 if (MaskedValueIsZero(RHS, Mask))
Chris Lattnerb4b25302005-09-18 07:22:02 +00003869 break;
3870 }
3871 }
Chris Lattneraf517572005-09-18 04:24:45 +00003872 return 0;
3873 case Instruction::Or:
3874 case Instruction::Xor:
Chris Lattnerb4b25302005-09-18 07:22:02 +00003875 // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
Reid Spencere0fc4df2006-10-20 07:07:24 +00003876 if ((Mask->getZExtValue() & Mask->getZExtValue()+1) == 0 &&
Chris Lattnerb4b25302005-09-18 07:22:02 +00003877 ConstantExpr::getAnd(N, Mask)->isNullValue())
Chris Lattneraf517572005-09-18 04:24:45 +00003878 break;
3879 return 0;
3880 }
3881
3882 Instruction *New;
3883 if (isSub)
3884 New = BinaryOperator::createSub(LHSI->getOperand(0), RHS, "fold");
3885 else
3886 New = BinaryOperator::createAdd(LHSI->getOperand(0), RHS, "fold");
3887 return InsertNewInstBefore(New, I);
3888}
3889
Chris Lattner113f4f42002-06-25 16:13:24 +00003890Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
Chris Lattnerdcf240a2003-03-10 21:43:22 +00003891 bool Changed = SimplifyCommutative(I);
Chris Lattner113f4f42002-06-25 16:13:24 +00003892 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00003893
Chris Lattner81a7a232004-10-16 18:11:37 +00003894 if (isa<UndefValue>(Op1)) // X & undef -> 0
3895 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3896
Chris Lattner86102b82005-01-01 16:22:27 +00003897 // and X, X = X
3898 if (Op0 == Op1)
Chris Lattnere6794492002-08-12 21:17:25 +00003899 return ReplaceInstUsesWith(I, Op1);
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00003900
Chris Lattner5b2edb12006-02-12 08:02:11 +00003901 // See if we can simplify any instructions used by the instruction whose sole
Chris Lattner5997cf92006-02-08 03:25:32 +00003902 // purpose is to compute bits we don't care about.
Chris Lattner0157e7f2006-02-11 09:31:47 +00003903 uint64_t KnownZero, KnownOne;
Reid Spencerd84d35b2007-02-15 02:26:10 +00003904 if (!isa<VectorType>(I.getType())) {
Reid Spencera94d3942007-01-19 21:13:56 +00003905 if (SimplifyDemandedBits(&I, cast<IntegerType>(I.getType())->getBitMask(),
Chris Lattner120ab032007-01-18 22:16:33 +00003906 KnownZero, KnownOne))
Chris Lattner5997cf92006-02-08 03:25:32 +00003907 return &I;
Chris Lattner120ab032007-01-18 22:16:33 +00003908 } else {
Reid Spencerd84d35b2007-02-15 02:26:10 +00003909 if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1)) {
Chris Lattner120ab032007-01-18 22:16:33 +00003910 if (CP->isAllOnesValue())
3911 return ReplaceInstUsesWith(I, I.getOperand(0));
3912 }
3913 }
Chris Lattner5997cf92006-02-08 03:25:32 +00003914
Zhou Sheng75b871f2007-01-11 12:24:14 +00003915 if (ConstantInt *AndRHS = dyn_cast<ConstantInt>(Op1)) {
Chris Lattnerab2dc4d2006-02-08 07:34:50 +00003916 uint64_t AndRHSMask = AndRHS->getZExtValue();
Reid Spencera94d3942007-01-19 21:13:56 +00003917 uint64_t TypeMask = cast<IntegerType>(Op0->getType())->getBitMask();
Chris Lattnerab2dc4d2006-02-08 07:34:50 +00003918 uint64_t NotAndRHS = AndRHSMask^TypeMask;
Chris Lattner86102b82005-01-01 16:22:27 +00003919
Chris Lattnerba1cb382003-09-19 17:17:26 +00003920 // Optimize a variety of ((val OP C1) & C2) combinations...
Reid Spencer2341c222007-02-02 02:16:23 +00003921 if (isa<BinaryOperator>(Op0)) {
Chris Lattnerba1cb382003-09-19 17:17:26 +00003922 Instruction *Op0I = cast<Instruction>(Op0);
Chris Lattner86102b82005-01-01 16:22:27 +00003923 Value *Op0LHS = Op0I->getOperand(0);
3924 Value *Op0RHS = Op0I->getOperand(1);
3925 switch (Op0I->getOpcode()) {
3926 case Instruction::Xor:
3927 case Instruction::Or:
Chris Lattner9e2c7fa2005-01-23 20:26:55 +00003928 // If the mask is only needed on one incoming arm, push it up.
3929 if (Op0I->hasOneUse()) {
3930 if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
3931 // Not masking anything out for the LHS, move to RHS.
3932 Instruction *NewRHS = BinaryOperator::createAnd(Op0RHS, AndRHS,
3933 Op0RHS->getName()+".masked");
3934 InsertNewInstBefore(NewRHS, I);
3935 return BinaryOperator::create(
3936 cast<BinaryOperator>(Op0I)->getOpcode(), Op0LHS, NewRHS);
Misha Brukmanb1c93172005-04-21 23:48:37 +00003937 }
Chris Lattnerc3ebf402006-02-07 07:27:52 +00003938 if (!isa<Constant>(Op0RHS) &&
Chris Lattner9e2c7fa2005-01-23 20:26:55 +00003939 MaskedValueIsZero(Op0RHS, NotAndRHS)) {
3940 // Not masking anything out for the RHS, move to LHS.
3941 Instruction *NewLHS = BinaryOperator::createAnd(Op0LHS, AndRHS,
3942 Op0LHS->getName()+".masked");
3943 InsertNewInstBefore(NewLHS, I);
3944 return BinaryOperator::create(
3945 cast<BinaryOperator>(Op0I)->getOpcode(), NewLHS, Op0RHS);
3946 }
3947 }
3948
Chris Lattner86102b82005-01-01 16:22:27 +00003949 break;
Chris Lattneraf517572005-09-18 04:24:45 +00003950 case Instruction::Add:
Chris Lattnerb4b25302005-09-18 07:22:02 +00003951 // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
3952 // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
3953 // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
3954 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
3955 return BinaryOperator::createAnd(V, AndRHS);
3956 if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
3957 return BinaryOperator::createAnd(V, AndRHS); // Add commutes
Chris Lattneraf517572005-09-18 04:24:45 +00003958 break;
3959
3960 case Instruction::Sub:
Chris Lattnerb4b25302005-09-18 07:22:02 +00003961 // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
3962 // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
3963 // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
3964 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
3965 return BinaryOperator::createAnd(V, AndRHS);
Chris Lattneraf517572005-09-18 04:24:45 +00003966 break;
Chris Lattner86102b82005-01-01 16:22:27 +00003967 }
3968
Chris Lattner16464b32003-07-23 19:25:52 +00003969 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
Chris Lattner86102b82005-01-01 16:22:27 +00003970 if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
Chris Lattnerba1cb382003-09-19 17:17:26 +00003971 return Res;
Chris Lattner86102b82005-01-01 16:22:27 +00003972 } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
Chris Lattner2c14cf72005-08-07 07:03:10 +00003973 // If this is an integer truncation or change from signed-to-unsigned, and
3974 // if the source is an and/or with immediate, transform it. This
3975 // frequently occurs for bitfield accesses.
3976 if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) {
Reid Spencer6c38f0b2006-11-27 01:05:10 +00003977 if ((isa<TruncInst>(CI) || isa<BitCastInst>(CI)) &&
Chris Lattner2c14cf72005-08-07 07:03:10 +00003978 CastOp->getNumOperands() == 2)
Chris Lattnerab2dc4d2006-02-08 07:34:50 +00003979 if (ConstantInt *AndCI = dyn_cast<ConstantInt>(CastOp->getOperand(1)))
Chris Lattner2c14cf72005-08-07 07:03:10 +00003980 if (CastOp->getOpcode() == Instruction::And) {
3981 // Change: and (cast (and X, C1) to T), C2
Reid Spencer6c38f0b2006-11-27 01:05:10 +00003982 // into : and (cast X to T), trunc_or_bitcast(C1)&C2
3983 // This will fold the two constants together, which may allow
3984 // other simplifications.
Reid Spencerbb65ebf2006-12-12 23:36:14 +00003985 Instruction *NewCast = CastInst::createTruncOrBitCast(
3986 CastOp->getOperand(0), I.getType(),
3987 CastOp->getName()+".shrunk");
Chris Lattner2c14cf72005-08-07 07:03:10 +00003988 NewCast = InsertNewInstBefore(NewCast, I);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00003989 // trunc_or_bitcast(C1)&C2
Reid Spencerbb65ebf2006-12-12 23:36:14 +00003990 Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType());
Reid Spencer6c38f0b2006-11-27 01:05:10 +00003991 C3 = ConstantExpr::getAnd(C3, AndRHS);
Chris Lattner2c14cf72005-08-07 07:03:10 +00003992 return BinaryOperator::createAnd(NewCast, C3);
3993 } else if (CastOp->getOpcode() == Instruction::Or) {
3994 // Change: and (cast (or X, C1) to T), C2
3995 // into : trunc(C1)&C2 iff trunc(C1)&C2 == C2
Chris Lattner2dc148e2006-12-12 19:11:20 +00003996 Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType());
Chris Lattner2c14cf72005-08-07 07:03:10 +00003997 if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS) // trunc(C1)&C2
3998 return ReplaceInstUsesWith(I, AndRHS);
3999 }
4000 }
Chris Lattner33217db2003-07-23 19:36:21 +00004001 }
Chris Lattner183b3362004-04-09 19:05:30 +00004002
4003 // Try to fold constant and into select arguments.
4004 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
Chris Lattner86102b82005-01-01 16:22:27 +00004005 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
Chris Lattner183b3362004-04-09 19:05:30 +00004006 return R;
Chris Lattner6a4adcd2004-09-29 05:07:12 +00004007 if (isa<PHINode>(Op0))
4008 if (Instruction *NV = FoldOpIntoPhi(I))
4009 return NV;
Chris Lattner49b47ae2003-07-23 17:57:01 +00004010 }
4011
Chris Lattnerbb74e222003-03-10 23:06:50 +00004012 Value *Op0NotVal = dyn_castNotVal(Op0);
4013 Value *Op1NotVal = dyn_castNotVal(Op1);
Chris Lattner3082c5a2003-02-18 19:28:33 +00004014
Chris Lattner023a4832004-06-18 06:07:51 +00004015 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
4016 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
4017
Misha Brukman9c003d82004-07-30 12:50:08 +00004018 // (~A & ~B) == (~(A | B)) - De Morgan's Law
Chris Lattnerbb74e222003-03-10 23:06:50 +00004019 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00004020 Instruction *Or = BinaryOperator::createOr(Op0NotVal, Op1NotVal,
4021 I.getName()+".demorgan");
Chris Lattner49b47ae2003-07-23 17:57:01 +00004022 InsertNewInstBefore(Or, I);
Chris Lattner3082c5a2003-02-18 19:28:33 +00004023 return BinaryOperator::createNot(Or);
4024 }
Chris Lattner8b10ab32006-02-13 23:07:23 +00004025
4026 {
4027 Value *A = 0, *B = 0;
Chris Lattner8b10ab32006-02-13 23:07:23 +00004028 if (match(Op0, m_Or(m_Value(A), m_Value(B))))
4029 if (A == Op1 || B == Op1) // (A | ?) & A --> A
4030 return ReplaceInstUsesWith(I, Op1);
4031 if (match(Op1, m_Or(m_Value(A), m_Value(B))))
4032 if (A == Op0 || B == Op0) // A & (A | ?) --> A
4033 return ReplaceInstUsesWith(I, Op0);
Chris Lattnerdcd07922006-04-01 08:03:55 +00004034
4035 if (Op0->hasOneUse() &&
4036 match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
4037 if (A == Op1) { // (A^B)&A -> A&(A^B)
4038 I.swapOperands(); // Simplify below
4039 std::swap(Op0, Op1);
4040 } else if (B == Op1) { // (A^B)&B -> B&(B^A)
4041 cast<BinaryOperator>(Op0)->swapOperands();
4042 I.swapOperands(); // Simplify below
4043 std::swap(Op0, Op1);
4044 }
4045 }
4046 if (Op1->hasOneUse() &&
4047 match(Op1, m_Xor(m_Value(A), m_Value(B)))) {
4048 if (B == Op0) { // B&(A^B) -> B&(B^A)
4049 cast<BinaryOperator>(Op1)->swapOperands();
4050 std::swap(A, B);
4051 }
4052 if (A == Op0) { // A&(A^B) -> A & ~B
4053 Instruction *NotB = BinaryOperator::createNot(B, "tmp");
4054 InsertNewInstBefore(NotB, I);
4055 return BinaryOperator::createAnd(A, NotB);
4056 }
4057 }
Chris Lattner8b10ab32006-02-13 23:07:23 +00004058 }
4059
Reid Spencer266e42b2006-12-23 06:05:41 +00004060 if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1)) {
4061 // (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
4062 if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
Chris Lattner3ac7c262003-08-13 20:16:26 +00004063 return R;
4064
Chris Lattner623826c2004-09-28 21:48:02 +00004065 Value *LHSVal, *RHSVal;
4066 ConstantInt *LHSCst, *RHSCst;
Reid Spencer266e42b2006-12-23 06:05:41 +00004067 ICmpInst::Predicate LHSCC, RHSCC;
4068 if (match(Op0, m_ICmp(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
4069 if (match(RHS, m_ICmp(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
4070 if (LHSVal == RHSVal && // Found (X icmp C1) & (X icmp C2)
4071 // ICMP_[GL]E X, CST is folded to ICMP_[GL]T elsewhere.
4072 LHSCC != ICmpInst::ICMP_UGE && LHSCC != ICmpInst::ICMP_ULE &&
4073 RHSCC != ICmpInst::ICMP_UGE && RHSCC != ICmpInst::ICMP_ULE &&
4074 LHSCC != ICmpInst::ICMP_SGE && LHSCC != ICmpInst::ICMP_SLE &&
4075 RHSCC != ICmpInst::ICMP_SGE && RHSCC != ICmpInst::ICMP_SLE) {
Chris Lattner623826c2004-09-28 21:48:02 +00004076 // Ensure that the larger constant is on the RHS.
Reid Spencer266e42b2006-12-23 06:05:41 +00004077 ICmpInst::Predicate GT = ICmpInst::isSignedPredicate(LHSCC) ?
4078 ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
4079 Constant *Cmp = ConstantExpr::getICmp(GT, LHSCst, RHSCst);
4080 ICmpInst *LHS = cast<ICmpInst>(Op0);
Reid Spencercddc9df2007-01-12 04:24:46 +00004081 if (cast<ConstantInt>(Cmp)->getZExtValue()) {
Chris Lattner623826c2004-09-28 21:48:02 +00004082 std::swap(LHS, RHS);
4083 std::swap(LHSCst, RHSCst);
4084 std::swap(LHSCC, RHSCC);
4085 }
4086
Reid Spencer266e42b2006-12-23 06:05:41 +00004087 // At this point, we know we have have two icmp instructions
Chris Lattner623826c2004-09-28 21:48:02 +00004088 // comparing a value against two constants and and'ing the result
4089 // together. Because of the above check, we know that we only have
Reid Spencer266e42b2006-12-23 06:05:41 +00004090 // icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know
4091 // (from the FoldICmpLogical check above), that the two constants
4092 // are not equal and that the larger constant is on the RHS
Chris Lattner623826c2004-09-28 21:48:02 +00004093 assert(LHSCst != RHSCst && "Compares not folded above?");
4094
4095 switch (LHSCC) {
4096 default: assert(0 && "Unknown integer condition code!");
Reid Spencer266e42b2006-12-23 06:05:41 +00004097 case ICmpInst::ICMP_EQ:
Chris Lattner623826c2004-09-28 21:48:02 +00004098 switch (RHSCC) {
4099 default: assert(0 && "Unknown integer condition code!");
Reid Spencer266e42b2006-12-23 06:05:41 +00004100 case ICmpInst::ICMP_EQ: // (X == 13 & X == 15) -> false
4101 case ICmpInst::ICMP_UGT: // (X == 13 & X > 15) -> false
4102 case ICmpInst::ICMP_SGT: // (X == 13 & X > 15) -> false
Zhou Sheng75b871f2007-01-11 12:24:14 +00004103 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
Reid Spencer266e42b2006-12-23 06:05:41 +00004104 case ICmpInst::ICMP_NE: // (X == 13 & X != 15) -> X == 13
4105 case ICmpInst::ICMP_ULT: // (X == 13 & X < 15) -> X == 13
4106 case ICmpInst::ICMP_SLT: // (X == 13 & X < 15) -> X == 13
Chris Lattner623826c2004-09-28 21:48:02 +00004107 return ReplaceInstUsesWith(I, LHS);
4108 }
Reid Spencer266e42b2006-12-23 06:05:41 +00004109 case ICmpInst::ICMP_NE:
Chris Lattner623826c2004-09-28 21:48:02 +00004110 switch (RHSCC) {
4111 default: assert(0 && "Unknown integer condition code!");
Reid Spencer266e42b2006-12-23 06:05:41 +00004112 case ICmpInst::ICMP_ULT:
4113 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X u< 14) -> X < 13
4114 return new ICmpInst(ICmpInst::ICMP_ULT, LHSVal, LHSCst);
4115 break; // (X != 13 & X u< 15) -> no change
4116 case ICmpInst::ICMP_SLT:
4117 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X s< 14) -> X < 13
4118 return new ICmpInst(ICmpInst::ICMP_SLT, LHSVal, LHSCst);
4119 break; // (X != 13 & X s< 15) -> no change
4120 case ICmpInst::ICMP_EQ: // (X != 13 & X == 15) -> X == 15
4121 case ICmpInst::ICMP_UGT: // (X != 13 & X u> 15) -> X u> 15
4122 case ICmpInst::ICMP_SGT: // (X != 13 & X s> 15) -> X s> 15
Chris Lattner623826c2004-09-28 21:48:02 +00004123 return ReplaceInstUsesWith(I, RHS);
Reid Spencer266e42b2006-12-23 06:05:41 +00004124 case ICmpInst::ICMP_NE:
4125 if (LHSCst == SubOne(RHSCst)){// (X != 13 & X != 14) -> X-13 >u 1
Chris Lattner623826c2004-09-28 21:48:02 +00004126 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
4127 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
4128 LHSVal->getName()+".off");
4129 InsertNewInstBefore(Add, I);
Chris Lattnerc8fb6de2007-01-27 23:08:34 +00004130 return new ICmpInst(ICmpInst::ICMP_UGT, Add,
4131 ConstantInt::get(Add->getType(), 1));
Chris Lattner623826c2004-09-28 21:48:02 +00004132 }
4133 break; // (X != 13 & X != 15) -> no change
4134 }
4135 break;
Reid Spencer266e42b2006-12-23 06:05:41 +00004136 case ICmpInst::ICMP_ULT:
Chris Lattner623826c2004-09-28 21:48:02 +00004137 switch (RHSCC) {
4138 default: assert(0 && "Unknown integer condition code!");
Reid Spencer266e42b2006-12-23 06:05:41 +00004139 case ICmpInst::ICMP_EQ: // (X u< 13 & X == 15) -> false
4140 case ICmpInst::ICMP_UGT: // (X u< 13 & X u> 15) -> false
Zhou Sheng75b871f2007-01-11 12:24:14 +00004141 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
Reid Spencer266e42b2006-12-23 06:05:41 +00004142 case ICmpInst::ICMP_SGT: // (X u< 13 & X s> 15) -> no change
4143 break;
4144 case ICmpInst::ICMP_NE: // (X u< 13 & X != 15) -> X u< 13
4145 case ICmpInst::ICMP_ULT: // (X u< 13 & X u< 15) -> X u< 13
Chris Lattner623826c2004-09-28 21:48:02 +00004146 return ReplaceInstUsesWith(I, LHS);
Reid Spencer266e42b2006-12-23 06:05:41 +00004147 case ICmpInst::ICMP_SLT: // (X u< 13 & X s< 15) -> no change
4148 break;
Chris Lattner623826c2004-09-28 21:48:02 +00004149 }
Reid Spencer266e42b2006-12-23 06:05:41 +00004150 break;
4151 case ICmpInst::ICMP_SLT:
Chris Lattner623826c2004-09-28 21:48:02 +00004152 switch (RHSCC) {
4153 default: assert(0 && "Unknown integer condition code!");
Reid Spencer266e42b2006-12-23 06:05:41 +00004154 case ICmpInst::ICMP_EQ: // (X s< 13 & X == 15) -> false
4155 case ICmpInst::ICMP_SGT: // (X s< 13 & X s> 15) -> false
Zhou Sheng75b871f2007-01-11 12:24:14 +00004156 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
Reid Spencer266e42b2006-12-23 06:05:41 +00004157 case ICmpInst::ICMP_UGT: // (X s< 13 & X u> 15) -> no change
4158 break;
4159 case ICmpInst::ICMP_NE: // (X s< 13 & X != 15) -> X < 13
4160 case ICmpInst::ICMP_SLT: // (X s< 13 & X s< 15) -> X < 13
Chris Lattner623826c2004-09-28 21:48:02 +00004161 return ReplaceInstUsesWith(I, LHS);
Reid Spencer266e42b2006-12-23 06:05:41 +00004162 case ICmpInst::ICMP_ULT: // (X s< 13 & X u< 15) -> no change
4163 break;
Chris Lattner623826c2004-09-28 21:48:02 +00004164 }
Reid Spencer266e42b2006-12-23 06:05:41 +00004165 break;
4166 case ICmpInst::ICMP_UGT:
4167 switch (RHSCC) {
4168 default: assert(0 && "Unknown integer condition code!");
4169 case ICmpInst::ICMP_EQ: // (X u> 13 & X == 15) -> X > 13
4170 return ReplaceInstUsesWith(I, LHS);
4171 case ICmpInst::ICMP_UGT: // (X u> 13 & X u> 15) -> X u> 15
4172 return ReplaceInstUsesWith(I, RHS);
4173 case ICmpInst::ICMP_SGT: // (X u> 13 & X s> 15) -> no change
4174 break;
4175 case ICmpInst::ICMP_NE:
4176 if (RHSCst == AddOne(LHSCst)) // (X u> 13 & X != 14) -> X u> 14
4177 return new ICmpInst(LHSCC, LHSVal, RHSCst);
4178 break; // (X u> 13 & X != 15) -> no change
4179 case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) ->(X-14) <u 1
4180 return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, false,
4181 true, I);
4182 case ICmpInst::ICMP_SLT: // (X u> 13 & X s< 15) -> no change
4183 break;
4184 }
4185 break;
4186 case ICmpInst::ICMP_SGT:
4187 switch (RHSCC) {
4188 default: assert(0 && "Unknown integer condition code!");
4189 case ICmpInst::ICMP_EQ: // (X s> 13 & X == 15) -> X s> 13
4190 return ReplaceInstUsesWith(I, LHS);
4191 case ICmpInst::ICMP_SGT: // (X s> 13 & X s> 15) -> X s> 15
4192 return ReplaceInstUsesWith(I, RHS);
4193 case ICmpInst::ICMP_UGT: // (X s> 13 & X u> 15) -> no change
4194 break;
4195 case ICmpInst::ICMP_NE:
4196 if (RHSCst == AddOne(LHSCst)) // (X s> 13 & X != 14) -> X s> 14
4197 return new ICmpInst(LHSCC, LHSVal, RHSCst);
4198 break; // (X s> 13 & X != 15) -> no change
4199 case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) ->(X-14) s< 1
4200 return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true,
4201 true, I);
4202 case ICmpInst::ICMP_ULT: // (X s> 13 & X u< 15) -> no change
4203 break;
4204 }
4205 break;
Chris Lattner623826c2004-09-28 21:48:02 +00004206 }
4207 }
4208 }
4209
Chris Lattner3af10532006-05-05 06:39:07 +00004210 // fold (and (cast A), (cast B)) -> (cast (and A, B))
Reid Spencer799b5bf2006-12-13 08:27:15 +00004211 if (CastInst *Op0C = dyn_cast<CastInst>(Op0))
4212 if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
4213 if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind ?
4214 const Type *SrcTy = Op0C->getOperand(0)->getType();
Chris Lattner03c49532007-01-15 02:27:26 +00004215 if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
Reid Spencer799b5bf2006-12-13 08:27:15 +00004216 // Only do this if the casts both really cause code to be generated.
Reid Spencer266e42b2006-12-23 06:05:41 +00004217 ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
4218 I.getType(), TD) &&
4219 ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
4220 I.getType(), TD)) {
Reid Spencer799b5bf2006-12-13 08:27:15 +00004221 Instruction *NewOp = BinaryOperator::createAnd(Op0C->getOperand(0),
4222 Op1C->getOperand(0),
4223 I.getName());
4224 InsertNewInstBefore(NewOp, I);
4225 return CastInst::create(Op0C->getOpcode(), NewOp, I.getType());
4226 }
Chris Lattner3af10532006-05-05 06:39:07 +00004227 }
Chris Lattnerf05d69a2006-11-14 07:46:50 +00004228
4229 // (X >> Z) & (Y >> Z) -> (X&Y) >> Z for all shifts.
Reid Spencer2341c222007-02-02 02:16:23 +00004230 if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
4231 if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
4232 if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
Chris Lattnerf05d69a2006-11-14 07:46:50 +00004233 SI0->getOperand(1) == SI1->getOperand(1) &&
4234 (SI0->hasOneUse() || SI1->hasOneUse())) {
4235 Instruction *NewOp =
4236 InsertNewInstBefore(BinaryOperator::createAnd(SI0->getOperand(0),
4237 SI1->getOperand(0),
4238 SI0->getName()), I);
Reid Spencer2341c222007-02-02 02:16:23 +00004239 return BinaryOperator::create(SI1->getOpcode(), NewOp,
4240 SI1->getOperand(1));
Chris Lattnerf05d69a2006-11-14 07:46:50 +00004241 }
Chris Lattner3af10532006-05-05 06:39:07 +00004242 }
4243
Chris Lattner113f4f42002-06-25 16:13:24 +00004244 return Changed ? &I : 0;
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00004245}
4246
Chris Lattnerc482a9e2006-06-15 19:07:26 +00004247/// CollectBSwapParts - Look to see if the specified value defines a single byte
4248/// in the result. If it does, and if the specified byte hasn't been filled in
4249/// yet, fill it in and return false.
Chris Lattner99c6cf62007-02-15 22:52:10 +00004250static bool CollectBSwapParts(Value *V, SmallVector<Value*, 8> &ByteValues) {
Chris Lattnerc482a9e2006-06-15 19:07:26 +00004251 Instruction *I = dyn_cast<Instruction>(V);
4252 if (I == 0) return true;
4253
4254 // If this is an or instruction, it is an inner node of the bswap.
4255 if (I->getOpcode() == Instruction::Or)
4256 return CollectBSwapParts(I->getOperand(0), ByteValues) ||
4257 CollectBSwapParts(I->getOperand(1), ByteValues);
4258
4259 // If this is a shift by a constant int, and it is "24", then its operand
4260 // defines a byte. We only handle unsigned types here.
Reid Spencer2341c222007-02-02 02:16:23 +00004261 if (I->isShift() && isa<ConstantInt>(I->getOperand(1))) {
Chris Lattnerc482a9e2006-06-15 19:07:26 +00004262 // Not shifting the entire input by N-1 bytes?
Reid Spencere0fc4df2006-10-20 07:07:24 +00004263 if (cast<ConstantInt>(I->getOperand(1))->getZExtValue() !=
Chris Lattnerc482a9e2006-06-15 19:07:26 +00004264 8*(ByteValues.size()-1))
4265 return true;
4266
4267 unsigned DestNo;
4268 if (I->getOpcode() == Instruction::Shl) {
4269 // X << 24 defines the top byte with the lowest of the input bytes.
4270 DestNo = ByteValues.size()-1;
4271 } else {
4272 // X >>u 24 defines the low byte with the highest of the input bytes.
4273 DestNo = 0;
4274 }
4275
4276 // If the destination byte value is already defined, the values are or'd
4277 // together, which isn't a bswap (unless it's an or of the same bits).
4278 if (ByteValues[DestNo] && ByteValues[DestNo] != I->getOperand(0))
4279 return true;
4280 ByteValues[DestNo] = I->getOperand(0);
4281 return false;
4282 }
4283
4284 // Otherwise, we can only handle and(shift X, imm), imm). Bail out of if we
4285 // don't have this.
4286 Value *Shift = 0, *ShiftLHS = 0;
4287 ConstantInt *AndAmt = 0, *ShiftAmt = 0;
4288 if (!match(I, m_And(m_Value(Shift), m_ConstantInt(AndAmt))) ||
4289 !match(Shift, m_Shift(m_Value(ShiftLHS), m_ConstantInt(ShiftAmt))))
4290 return true;
4291 Instruction *SI = cast<Instruction>(Shift);
4292
4293 // Make sure that the shift amount is by a multiple of 8 and isn't too big.
Reid Spencere0fc4df2006-10-20 07:07:24 +00004294 if (ShiftAmt->getZExtValue() & 7 ||
4295 ShiftAmt->getZExtValue() > 8*ByteValues.size())
Chris Lattnerc482a9e2006-06-15 19:07:26 +00004296 return true;
4297
4298 // Turn 0xFF -> 0, 0xFF00 -> 1, 0xFF0000 -> 2, etc.
4299 unsigned DestByte;
4300 for (DestByte = 0; DestByte != ByteValues.size(); ++DestByte)
Reid Spencere0fc4df2006-10-20 07:07:24 +00004301 if (AndAmt->getZExtValue() == uint64_t(0xFF) << 8*DestByte)
Chris Lattnerc482a9e2006-06-15 19:07:26 +00004302 break;
4303 // Unknown mask for bswap.
4304 if (DestByte == ByteValues.size()) return true;
4305
Reid Spencere0fc4df2006-10-20 07:07:24 +00004306 unsigned ShiftBytes = ShiftAmt->getZExtValue()/8;
Chris Lattnerc482a9e2006-06-15 19:07:26 +00004307 unsigned SrcByte;
4308 if (SI->getOpcode() == Instruction::Shl)
4309 SrcByte = DestByte - ShiftBytes;
4310 else
4311 SrcByte = DestByte + ShiftBytes;
4312
4313 // If the SrcByte isn't a bswapped value from the DestByte, reject it.
4314 if (SrcByte != ByteValues.size()-DestByte-1)
4315 return true;
4316
4317 // If the destination byte value is already defined, the values are or'd
4318 // together, which isn't a bswap (unless it's an or of the same bits).
4319 if (ByteValues[DestByte] && ByteValues[DestByte] != SI->getOperand(0))
4320 return true;
4321 ByteValues[DestByte] = SI->getOperand(0);
4322 return false;
4323}
4324
4325/// MatchBSwap - Given an OR instruction, check to see if this is a bswap idiom.
4326/// If so, insert the new bswap intrinsic and return it.
4327Instruction *InstCombiner::MatchBSwap(BinaryOperator &I) {
Reid Spencer2341c222007-02-02 02:16:23 +00004328 // We cannot bswap one byte.
Reid Spencerc635f472006-12-31 05:48:39 +00004329 if (I.getType() == Type::Int8Ty)
Chris Lattnerc482a9e2006-06-15 19:07:26 +00004330 return 0;
4331
4332 /// ByteValues - For each byte of the result, we keep track of which value
4333 /// defines each byte.
Chris Lattner99c6cf62007-02-15 22:52:10 +00004334 SmallVector<Value*, 8> ByteValues;
Reid Spencer7a9c62b2007-01-12 07:05:14 +00004335 ByteValues.resize(TD->getTypeSize(I.getType()));
Chris Lattnerc482a9e2006-06-15 19:07:26 +00004336
4337 // Try to find all the pieces corresponding to the bswap.
4338 if (CollectBSwapParts(I.getOperand(0), ByteValues) ||
4339 CollectBSwapParts(I.getOperand(1), ByteValues))
4340 return 0;
4341
4342 // Check to see if all of the bytes come from the same value.
4343 Value *V = ByteValues[0];
4344 if (V == 0) return 0; // Didn't find a byte? Must be zero.
4345
4346 // Check to make sure that all of the bytes come from the same value.
4347 for (unsigned i = 1, e = ByteValues.size(); i != e; ++i)
4348 if (ByteValues[i] != V)
4349 return 0;
4350
4351 // If they do then *success* we can turn this into a bswap. Figure out what
4352 // bswap to make it into.
4353 Module *M = I.getParent()->getParent()->getParent();
Chris Lattner091b6ea2006-07-11 18:31:26 +00004354 const char *FnName = 0;
Reid Spencerc635f472006-12-31 05:48:39 +00004355 if (I.getType() == Type::Int16Ty)
Chris Lattnerc482a9e2006-06-15 19:07:26 +00004356 FnName = "llvm.bswap.i16";
Reid Spencerc635f472006-12-31 05:48:39 +00004357 else if (I.getType() == Type::Int32Ty)
Chris Lattnerc482a9e2006-06-15 19:07:26 +00004358 FnName = "llvm.bswap.i32";
Reid Spencerc635f472006-12-31 05:48:39 +00004359 else if (I.getType() == Type::Int64Ty)
Chris Lattnerc482a9e2006-06-15 19:07:26 +00004360 FnName = "llvm.bswap.i64";
4361 else
4362 assert(0 && "Unknown integer type!");
Chris Lattnerfbc524f2007-01-07 06:58:05 +00004363 Constant *F = M->getOrInsertFunction(FnName, I.getType(), I.getType(), NULL);
Chris Lattnerc482a9e2006-06-15 19:07:26 +00004364 return new CallInst(F, V);
4365}
4366
4367
Chris Lattner113f4f42002-06-25 16:13:24 +00004368Instruction *InstCombiner::visitOr(BinaryOperator &I) {
Chris Lattnerdcf240a2003-03-10 21:43:22 +00004369 bool Changed = SimplifyCommutative(I);
Chris Lattner113f4f42002-06-25 16:13:24 +00004370 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00004371
Chris Lattner81a7a232004-10-16 18:11:37 +00004372 if (isa<UndefValue>(Op1))
4373 return ReplaceInstUsesWith(I, // X | undef -> -1
Zhou Sheng75b871f2007-01-11 12:24:14 +00004374 ConstantInt::getAllOnesValue(I.getType()));
Chris Lattner81a7a232004-10-16 18:11:37 +00004375
Chris Lattner5b2edb12006-02-12 08:02:11 +00004376 // or X, X = X
4377 if (Op0 == Op1)
Chris Lattnere6794492002-08-12 21:17:25 +00004378 return ReplaceInstUsesWith(I, Op0);
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00004379
Chris Lattner5b2edb12006-02-12 08:02:11 +00004380 // See if we can simplify any instructions used by the instruction whose sole
4381 // purpose is to compute bits we don't care about.
4382 uint64_t KnownZero, KnownOne;
Reid Spencerd84d35b2007-02-15 02:26:10 +00004383 if (!isa<VectorType>(I.getType()) &&
Reid Spencera94d3942007-01-19 21:13:56 +00004384 SimplifyDemandedBits(&I, cast<IntegerType>(I.getType())->getBitMask(),
Chris Lattner5b2edb12006-02-12 08:02:11 +00004385 KnownZero, KnownOne))
4386 return &I;
4387
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00004388 // or X, -1 == -1
Zhou Sheng75b871f2007-01-11 12:24:14 +00004389 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
Chris Lattner330628a2006-01-06 17:59:59 +00004390 ConstantInt *C1 = 0; Value *X = 0;
Chris Lattnerd4252a72004-07-30 07:50:03 +00004391 // (X & C1) | C2 --> (X | C2) & (C1|C2)
4392 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
Chris Lattner6e0123b2007-02-11 01:23:03 +00004393 Instruction *Or = BinaryOperator::createOr(X, RHS);
Chris Lattnerd4252a72004-07-30 07:50:03 +00004394 InsertNewInstBefore(Or, I);
Chris Lattner6e0123b2007-02-11 01:23:03 +00004395 Or->takeName(Op0);
Chris Lattnerd4252a72004-07-30 07:50:03 +00004396 return BinaryOperator::createAnd(Or, ConstantExpr::getOr(RHS, C1));
4397 }
Chris Lattner8f0d1562003-07-23 18:29:44 +00004398
Chris Lattnerd4252a72004-07-30 07:50:03 +00004399 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
4400 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
Chris Lattner6e0123b2007-02-11 01:23:03 +00004401 Instruction *Or = BinaryOperator::createOr(X, RHS);
Chris Lattnerd4252a72004-07-30 07:50:03 +00004402 InsertNewInstBefore(Or, I);
Chris Lattner6e0123b2007-02-11 01:23:03 +00004403 Or->takeName(Op0);
Chris Lattnerd4252a72004-07-30 07:50:03 +00004404 return BinaryOperator::createXor(Or,
4405 ConstantExpr::getAnd(C1, ConstantExpr::getNot(RHS)));
Chris Lattner8f0d1562003-07-23 18:29:44 +00004406 }
Chris Lattner183b3362004-04-09 19:05:30 +00004407
4408 // Try to fold constant and into select arguments.
4409 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
Chris Lattner86102b82005-01-01 16:22:27 +00004410 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
Chris Lattner183b3362004-04-09 19:05:30 +00004411 return R;
Chris Lattner6a4adcd2004-09-29 05:07:12 +00004412 if (isa<PHINode>(Op0))
4413 if (Instruction *NV = FoldOpIntoPhi(I))
4414 return NV;
Chris Lattner8f0d1562003-07-23 18:29:44 +00004415 }
4416
Chris Lattner330628a2006-01-06 17:59:59 +00004417 Value *A = 0, *B = 0;
4418 ConstantInt *C1 = 0, *C2 = 0;
Chris Lattner4294cec2005-05-07 23:49:08 +00004419
4420 if (match(Op0, m_And(m_Value(A), m_Value(B))))
4421 if (A == Op1 || B == Op1) // (A & ?) | A --> A
4422 return ReplaceInstUsesWith(I, Op1);
4423 if (match(Op1, m_And(m_Value(A), m_Value(B))))
4424 if (A == Op0 || B == Op0) // A | (A & ?) --> A
4425 return ReplaceInstUsesWith(I, Op0);
4426
Chris Lattnerb7845d62006-07-10 20:25:24 +00004427 // (A | B) | C and A | (B | C) -> bswap if possible.
4428 // (A >> B) | (C << D) and (A << B) | (B >> C) -> bswap if possible.
Chris Lattnerc482a9e2006-06-15 19:07:26 +00004429 if (match(Op0, m_Or(m_Value(), m_Value())) ||
Chris Lattnerb7845d62006-07-10 20:25:24 +00004430 match(Op1, m_Or(m_Value(), m_Value())) ||
4431 (match(Op0, m_Shift(m_Value(), m_Value())) &&
4432 match(Op1, m_Shift(m_Value(), m_Value())))) {
Chris Lattnerc482a9e2006-06-15 19:07:26 +00004433 if (Instruction *BSwap = MatchBSwap(I))
4434 return BSwap;
4435 }
4436
Chris Lattnerb62f5082005-05-09 04:58:36 +00004437 // (X^C)|Y -> (X|Y)^C iff Y&C == 0
4438 if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
Chris Lattnerc3ebf402006-02-07 07:27:52 +00004439 MaskedValueIsZero(Op1, C1->getZExtValue())) {
Chris Lattner6e0123b2007-02-11 01:23:03 +00004440 Instruction *NOr = BinaryOperator::createOr(A, Op1);
4441 InsertNewInstBefore(NOr, I);
4442 NOr->takeName(Op0);
4443 return BinaryOperator::createXor(NOr, C1);
Chris Lattnerb62f5082005-05-09 04:58:36 +00004444 }
4445
4446 // Y|(X^C) -> (X|Y)^C iff Y&C == 0
4447 if (Op1->hasOneUse() && match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
Chris Lattnerc3ebf402006-02-07 07:27:52 +00004448 MaskedValueIsZero(Op0, C1->getZExtValue())) {
Chris Lattner6e0123b2007-02-11 01:23:03 +00004449 Instruction *NOr = BinaryOperator::createOr(A, Op0);
4450 InsertNewInstBefore(NOr, I);
4451 NOr->takeName(Op0);
4452 return BinaryOperator::createXor(NOr, C1);
Chris Lattnerb62f5082005-05-09 04:58:36 +00004453 }
4454
Chris Lattner15212982005-09-18 03:42:07 +00004455 // (A & C1)|(B & C2)
Chris Lattnerd4252a72004-07-30 07:50:03 +00004456 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
Chris Lattner15212982005-09-18 03:42:07 +00004457 match(Op1, m_And(m_Value(B), m_ConstantInt(C2)))) {
4458
4459 if (A == B) // (A & C1)|(A & C2) == A & (C1|C2)
4460 return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2));
4461
4462
Chris Lattner01f56c62005-09-18 06:02:59 +00004463 // If we have: ((V + N) & C1) | (V & C2)
4464 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
4465 // replace with V+N.
4466 if (C1 == ConstantExpr::getNot(C2)) {
Chris Lattner330628a2006-01-06 17:59:59 +00004467 Value *V1 = 0, *V2 = 0;
Reid Spencere0fc4df2006-10-20 07:07:24 +00004468 if ((C2->getZExtValue() & (C2->getZExtValue()+1)) == 0 && // C2 == 0+1+
Chris Lattner01f56c62005-09-18 06:02:59 +00004469 match(A, m_Add(m_Value(V1), m_Value(V2)))) {
4470 // Add commutes, try both ways.
Chris Lattnerc3ebf402006-02-07 07:27:52 +00004471 if (V1 == B && MaskedValueIsZero(V2, C2->getZExtValue()))
Chris Lattner01f56c62005-09-18 06:02:59 +00004472 return ReplaceInstUsesWith(I, A);
Chris Lattnerc3ebf402006-02-07 07:27:52 +00004473 if (V2 == B && MaskedValueIsZero(V1, C2->getZExtValue()))
Chris Lattner01f56c62005-09-18 06:02:59 +00004474 return ReplaceInstUsesWith(I, A);
4475 }
4476 // Or commutes, try both ways.
Reid Spencere0fc4df2006-10-20 07:07:24 +00004477 if ((C1->getZExtValue() & (C1->getZExtValue()+1)) == 0 &&
Chris Lattner01f56c62005-09-18 06:02:59 +00004478 match(B, m_Add(m_Value(V1), m_Value(V2)))) {
4479 // Add commutes, try both ways.
Chris Lattnerc3ebf402006-02-07 07:27:52 +00004480 if (V1 == A && MaskedValueIsZero(V2, C1->getZExtValue()))
Chris Lattner01f56c62005-09-18 06:02:59 +00004481 return ReplaceInstUsesWith(I, B);
Chris Lattnerc3ebf402006-02-07 07:27:52 +00004482 if (V2 == A && MaskedValueIsZero(V1, C1->getZExtValue()))
Chris Lattner01f56c62005-09-18 06:02:59 +00004483 return ReplaceInstUsesWith(I, B);
Chris Lattner15212982005-09-18 03:42:07 +00004484 }
4485 }
4486 }
Chris Lattnerf05d69a2006-11-14 07:46:50 +00004487
4488 // (X >> Z) | (Y >> Z) -> (X|Y) >> Z for all shifts.
Reid Spencer2341c222007-02-02 02:16:23 +00004489 if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
4490 if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
4491 if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
Chris Lattnerf05d69a2006-11-14 07:46:50 +00004492 SI0->getOperand(1) == SI1->getOperand(1) &&
4493 (SI0->hasOneUse() || SI1->hasOneUse())) {
4494 Instruction *NewOp =
4495 InsertNewInstBefore(BinaryOperator::createOr(SI0->getOperand(0),
4496 SI1->getOperand(0),
4497 SI0->getName()), I);
Reid Spencer2341c222007-02-02 02:16:23 +00004498 return BinaryOperator::create(SI1->getOpcode(), NewOp,
4499 SI1->getOperand(1));
Chris Lattnerf05d69a2006-11-14 07:46:50 +00004500 }
4501 }
Chris Lattner812aab72003-08-12 19:11:07 +00004502
Chris Lattnerd4252a72004-07-30 07:50:03 +00004503 if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
4504 if (A == Op1) // ~A | A == -1
Misha Brukmanb1c93172005-04-21 23:48:37 +00004505 return ReplaceInstUsesWith(I,
Zhou Sheng75b871f2007-01-11 12:24:14 +00004506 ConstantInt::getAllOnesValue(I.getType()));
Chris Lattnerd4252a72004-07-30 07:50:03 +00004507 } else {
4508 A = 0;
4509 }
Chris Lattner4294cec2005-05-07 23:49:08 +00004510 // Note, A is still live here!
Chris Lattnerd4252a72004-07-30 07:50:03 +00004511 if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
4512 if (Op0 == B)
Misha Brukmanb1c93172005-04-21 23:48:37 +00004513 return ReplaceInstUsesWith(I,
Zhou Sheng75b871f2007-01-11 12:24:14 +00004514 ConstantInt::getAllOnesValue(I.getType()));
Chris Lattner3e327a42003-03-10 23:13:59 +00004515
Misha Brukman9c003d82004-07-30 12:50:08 +00004516 // (~A | ~B) == (~(A & B)) - De Morgan's Law
Chris Lattnerd4252a72004-07-30 07:50:03 +00004517 if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
4518 Value *And = InsertNewInstBefore(BinaryOperator::createAnd(A, B,
4519 I.getName()+".demorgan"), I);
4520 return BinaryOperator::createNot(And);
4521 }
Chris Lattner3e327a42003-03-10 23:13:59 +00004522 }
Chris Lattner3082c5a2003-02-18 19:28:33 +00004523
Reid Spencer266e42b2006-12-23 06:05:41 +00004524 // (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B)
4525 if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1))) {
4526 if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
Chris Lattner3ac7c262003-08-13 20:16:26 +00004527 return R;
4528
Chris Lattnerdcf756e2004-09-28 22:33:08 +00004529 Value *LHSVal, *RHSVal;
4530 ConstantInt *LHSCst, *RHSCst;
Reid Spencer266e42b2006-12-23 06:05:41 +00004531 ICmpInst::Predicate LHSCC, RHSCC;
4532 if (match(Op0, m_ICmp(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
4533 if (match(RHS, m_ICmp(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
4534 if (LHSVal == RHSVal && // Found (X icmp C1) | (X icmp C2)
4535 // icmp [us][gl]e x, cst is folded to icmp [us][gl]t elsewhere.
4536 LHSCC != ICmpInst::ICMP_UGE && LHSCC != ICmpInst::ICMP_ULE &&
4537 RHSCC != ICmpInst::ICMP_UGE && RHSCC != ICmpInst::ICMP_ULE &&
4538 LHSCC != ICmpInst::ICMP_SGE && LHSCC != ICmpInst::ICMP_SLE &&
4539 RHSCC != ICmpInst::ICMP_SGE && RHSCC != ICmpInst::ICMP_SLE) {
Chris Lattnerdcf756e2004-09-28 22:33:08 +00004540 // Ensure that the larger constant is on the RHS.
Reid Spencer266e42b2006-12-23 06:05:41 +00004541 ICmpInst::Predicate GT = ICmpInst::isSignedPredicate(LHSCC) ?
4542 ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
4543 Constant *Cmp = ConstantExpr::getICmp(GT, LHSCst, RHSCst);
4544 ICmpInst *LHS = cast<ICmpInst>(Op0);
Reid Spencercddc9df2007-01-12 04:24:46 +00004545 if (cast<ConstantInt>(Cmp)->getZExtValue()) {
Chris Lattnerdcf756e2004-09-28 22:33:08 +00004546 std::swap(LHS, RHS);
4547 std::swap(LHSCst, RHSCst);
4548 std::swap(LHSCC, RHSCC);
4549 }
4550
Reid Spencer266e42b2006-12-23 06:05:41 +00004551 // At this point, we know we have have two icmp instructions
Chris Lattnerdcf756e2004-09-28 22:33:08 +00004552 // comparing a value against two constants and or'ing the result
4553 // together. Because of the above check, we know that we only have
Reid Spencer266e42b2006-12-23 06:05:41 +00004554 // ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the
4555 // FoldICmpLogical check above), that the two constants are not
Chris Lattnerdcf756e2004-09-28 22:33:08 +00004556 // equal.
4557 assert(LHSCst != RHSCst && "Compares not folded above?");
4558
4559 switch (LHSCC) {
4560 default: assert(0 && "Unknown integer condition code!");
Reid Spencer266e42b2006-12-23 06:05:41 +00004561 case ICmpInst::ICMP_EQ:
Chris Lattnerdcf756e2004-09-28 22:33:08 +00004562 switch (RHSCC) {
4563 default: assert(0 && "Unknown integer condition code!");
Reid Spencer266e42b2006-12-23 06:05:41 +00004564 case ICmpInst::ICMP_EQ:
Chris Lattnerdcf756e2004-09-28 22:33:08 +00004565 if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2
4566 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
4567 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
4568 LHSVal->getName()+".off");
4569 InsertNewInstBefore(Add, I);
Chris Lattnerdcf756e2004-09-28 22:33:08 +00004570 AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
Reid Spencer266e42b2006-12-23 06:05:41 +00004571 return new ICmpInst(ICmpInst::ICMP_ULT, Add, AddCST);
Chris Lattnerdcf756e2004-09-28 22:33:08 +00004572 }
Reid Spencer266e42b2006-12-23 06:05:41 +00004573 break; // (X == 13 | X == 15) -> no change
4574 case ICmpInst::ICMP_UGT: // (X == 13 | X u> 14) -> no change
4575 case ICmpInst::ICMP_SGT: // (X == 13 | X s> 14) -> no change
Chris Lattner5c219462005-04-19 06:04:18 +00004576 break;
Reid Spencer266e42b2006-12-23 06:05:41 +00004577 case ICmpInst::ICMP_NE: // (X == 13 | X != 15) -> X != 15
4578 case ICmpInst::ICMP_ULT: // (X == 13 | X u< 15) -> X u< 15
4579 case ICmpInst::ICMP_SLT: // (X == 13 | X s< 15) -> X s< 15
Chris Lattnerdcf756e2004-09-28 22:33:08 +00004580 return ReplaceInstUsesWith(I, RHS);
4581 }
4582 break;
Reid Spencer266e42b2006-12-23 06:05:41 +00004583 case ICmpInst::ICMP_NE:
Chris Lattnerdcf756e2004-09-28 22:33:08 +00004584 switch (RHSCC) {
4585 default: assert(0 && "Unknown integer condition code!");
Reid Spencer266e42b2006-12-23 06:05:41 +00004586 case ICmpInst::ICMP_EQ: // (X != 13 | X == 15) -> X != 13
4587 case ICmpInst::ICMP_UGT: // (X != 13 | X u> 15) -> X != 13
4588 case ICmpInst::ICMP_SGT: // (X != 13 | X s> 15) -> X != 13
Chris Lattnerdcf756e2004-09-28 22:33:08 +00004589 return ReplaceInstUsesWith(I, LHS);
Reid Spencer266e42b2006-12-23 06:05:41 +00004590 case ICmpInst::ICMP_NE: // (X != 13 | X != 15) -> true
4591 case ICmpInst::ICMP_ULT: // (X != 13 | X u< 15) -> true
4592 case ICmpInst::ICMP_SLT: // (X != 13 | X s< 15) -> true
Zhou Sheng75b871f2007-01-11 12:24:14 +00004593 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
Chris Lattnerdcf756e2004-09-28 22:33:08 +00004594 }
4595 break;
Reid Spencer266e42b2006-12-23 06:05:41 +00004596 case ICmpInst::ICMP_ULT:
Chris Lattnerdcf756e2004-09-28 22:33:08 +00004597 switch (RHSCC) {
4598 default: assert(0 && "Unknown integer condition code!");
Reid Spencer266e42b2006-12-23 06:05:41 +00004599 case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change
Chris Lattnerdcf756e2004-09-28 22:33:08 +00004600 break;
Reid Spencer266e42b2006-12-23 06:05:41 +00004601 case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) ->(X-13) u> 2
4602 return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false,
4603 false, I);
4604 case ICmpInst::ICMP_SGT: // (X u< 13 | X s> 15) -> no change
4605 break;
4606 case ICmpInst::ICMP_NE: // (X u< 13 | X != 15) -> X != 15
4607 case ICmpInst::ICMP_ULT: // (X u< 13 | X u< 15) -> X u< 15
Chris Lattnerdcf756e2004-09-28 22:33:08 +00004608 return ReplaceInstUsesWith(I, RHS);
Reid Spencer266e42b2006-12-23 06:05:41 +00004609 case ICmpInst::ICMP_SLT: // (X u< 13 | X s< 15) -> no change
4610 break;
Chris Lattnerdcf756e2004-09-28 22:33:08 +00004611 }
4612 break;
Reid Spencer266e42b2006-12-23 06:05:41 +00004613 case ICmpInst::ICMP_SLT:
Chris Lattnerdcf756e2004-09-28 22:33:08 +00004614 switch (RHSCC) {
4615 default: assert(0 && "Unknown integer condition code!");
Reid Spencer266e42b2006-12-23 06:05:41 +00004616 case ICmpInst::ICMP_EQ: // (X s< 13 | X == 14) -> no change
4617 break;
4618 case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) ->(X-13) s> 2
4619 return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), true,
4620 false, I);
4621 case ICmpInst::ICMP_UGT: // (X s< 13 | X u> 15) -> no change
4622 break;
4623 case ICmpInst::ICMP_NE: // (X s< 13 | X != 15) -> X != 15
4624 case ICmpInst::ICMP_SLT: // (X s< 13 | X s< 15) -> X s< 15
4625 return ReplaceInstUsesWith(I, RHS);
4626 case ICmpInst::ICMP_ULT: // (X s< 13 | X u< 15) -> no change
4627 break;
Chris Lattnerdcf756e2004-09-28 22:33:08 +00004628 }
Reid Spencer266e42b2006-12-23 06:05:41 +00004629 break;
4630 case ICmpInst::ICMP_UGT:
4631 switch (RHSCC) {
4632 default: assert(0 && "Unknown integer condition code!");
4633 case ICmpInst::ICMP_EQ: // (X u> 13 | X == 15) -> X u> 13
4634 case ICmpInst::ICMP_UGT: // (X u> 13 | X u> 15) -> X u> 13
4635 return ReplaceInstUsesWith(I, LHS);
4636 case ICmpInst::ICMP_SGT: // (X u> 13 | X s> 15) -> no change
4637 break;
4638 case ICmpInst::ICMP_NE: // (X u> 13 | X != 15) -> true
4639 case ICmpInst::ICMP_ULT: // (X u> 13 | X u< 15) -> true
Zhou Sheng75b871f2007-01-11 12:24:14 +00004640 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
Reid Spencer266e42b2006-12-23 06:05:41 +00004641 case ICmpInst::ICMP_SLT: // (X u> 13 | X s< 15) -> no change
4642 break;
4643 }
4644 break;
4645 case ICmpInst::ICMP_SGT:
4646 switch (RHSCC) {
4647 default: assert(0 && "Unknown integer condition code!");
4648 case ICmpInst::ICMP_EQ: // (X s> 13 | X == 15) -> X > 13
4649 case ICmpInst::ICMP_SGT: // (X s> 13 | X s> 15) -> X > 13
4650 return ReplaceInstUsesWith(I, LHS);
4651 case ICmpInst::ICMP_UGT: // (X s> 13 | X u> 15) -> no change
4652 break;
4653 case ICmpInst::ICMP_NE: // (X s> 13 | X != 15) -> true
4654 case ICmpInst::ICMP_SLT: // (X s> 13 | X s< 15) -> true
Zhou Sheng75b871f2007-01-11 12:24:14 +00004655 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
Reid Spencer266e42b2006-12-23 06:05:41 +00004656 case ICmpInst::ICMP_ULT: // (X s> 13 | X u< 15) -> no change
4657 break;
4658 }
4659 break;
Chris Lattnerdcf756e2004-09-28 22:33:08 +00004660 }
4661 }
4662 }
Chris Lattner3af10532006-05-05 06:39:07 +00004663
4664 // fold (or (cast A), (cast B)) -> (cast (or A, B))
Reid Spencer799b5bf2006-12-13 08:27:15 +00004665 if (CastInst *Op0C = dyn_cast<CastInst>(Op0))
Chris Lattner3af10532006-05-05 06:39:07 +00004666 if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
Reid Spencer799b5bf2006-12-13 08:27:15 +00004667 if (Op0C->getOpcode() == Op1C->getOpcode()) {// same cast kind ?
4668 const Type *SrcTy = Op0C->getOperand(0)->getType();
Chris Lattner03c49532007-01-15 02:27:26 +00004669 if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
Reid Spencer799b5bf2006-12-13 08:27:15 +00004670 // Only do this if the casts both really cause code to be generated.
Reid Spencer266e42b2006-12-23 06:05:41 +00004671 ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
4672 I.getType(), TD) &&
4673 ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
4674 I.getType(), TD)) {
Reid Spencer799b5bf2006-12-13 08:27:15 +00004675 Instruction *NewOp = BinaryOperator::createOr(Op0C->getOperand(0),
4676 Op1C->getOperand(0),
4677 I.getName());
4678 InsertNewInstBefore(NewOp, I);
4679 return CastInst::create(Op0C->getOpcode(), NewOp, I.getType());
4680 }
Chris Lattner3af10532006-05-05 06:39:07 +00004681 }
Chris Lattner3af10532006-05-05 06:39:07 +00004682
Chris Lattner15212982005-09-18 03:42:07 +00004683
Chris Lattner113f4f42002-06-25 16:13:24 +00004684 return Changed ? &I : 0;
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00004685}
4686
Chris Lattnerc2076352004-02-16 01:20:27 +00004687// XorSelf - Implements: X ^ X --> 0
4688struct XorSelf {
4689 Value *RHS;
4690 XorSelf(Value *rhs) : RHS(rhs) {}
4691 bool shouldApply(Value *LHS) const { return LHS == RHS; }
4692 Instruction *apply(BinaryOperator &Xor) const {
4693 return &Xor;
4694 }
4695};
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00004696
4697
Chris Lattner113f4f42002-06-25 16:13:24 +00004698Instruction *InstCombiner::visitXor(BinaryOperator &I) {
Chris Lattnerdcf240a2003-03-10 21:43:22 +00004699 bool Changed = SimplifyCommutative(I);
Chris Lattner113f4f42002-06-25 16:13:24 +00004700 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00004701
Chris Lattner81a7a232004-10-16 18:11:37 +00004702 if (isa<UndefValue>(Op1))
4703 return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
4704
Chris Lattnerc2076352004-02-16 01:20:27 +00004705 // xor X, X = 0, even if X is nested in a sequence of Xor's.
4706 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
4707 assert(Result == &I && "AssociativeOpt didn't work?");
Chris Lattnere6794492002-08-12 21:17:25 +00004708 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
Chris Lattnerc2076352004-02-16 01:20:27 +00004709 }
Chris Lattner5b2edb12006-02-12 08:02:11 +00004710
4711 // See if we can simplify any instructions used by the instruction whose sole
4712 // purpose is to compute bits we don't care about.
4713 uint64_t KnownZero, KnownOne;
Reid Spencerd84d35b2007-02-15 02:26:10 +00004714 if (!isa<VectorType>(I.getType()) &&
Reid Spencera94d3942007-01-19 21:13:56 +00004715 SimplifyDemandedBits(&I, cast<IntegerType>(I.getType())->getBitMask(),
Chris Lattner5b2edb12006-02-12 08:02:11 +00004716 KnownZero, KnownOne))
4717 return &I;
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00004718
Zhou Sheng75b871f2007-01-11 12:24:14 +00004719 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
Reid Spencer266e42b2006-12-23 06:05:41 +00004720 // xor (icmp A, B), true = not (icmp A, B) = !icmp A, B
4721 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Op0))
Zhou Sheng75b871f2007-01-11 12:24:14 +00004722 if (RHS == ConstantInt::getTrue() && ICI->hasOneUse())
Reid Spencer266e42b2006-12-23 06:05:41 +00004723 return new ICmpInst(ICI->getInversePredicate(),
4724 ICI->getOperand(0), ICI->getOperand(1));
Chris Lattnere5806662003-11-04 23:50:51 +00004725
Reid Spencer266e42b2006-12-23 06:05:41 +00004726 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
Chris Lattner8f2f5982003-11-05 01:06:05 +00004727 // ~(c-X) == X-c-1 == X+(-c-1)
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00004728 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
4729 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00004730 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
4731 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00004732 ConstantInt::get(I.getType(), 1));
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00004733 return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS);
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00004734 }
Chris Lattner023a4832004-06-18 06:07:51 +00004735
4736 // ~(~X & Y) --> (X | ~Y)
4737 if (Op0I->getOpcode() == Instruction::And && RHS->isAllOnesValue()) {
4738 if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
4739 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
4740 Instruction *NotY =
Misha Brukmanb1c93172005-04-21 23:48:37 +00004741 BinaryOperator::createNot(Op0I->getOperand(1),
Chris Lattner023a4832004-06-18 06:07:51 +00004742 Op0I->getOperand(1)->getName()+".not");
4743 InsertNewInstBefore(NotY, I);
4744 return BinaryOperator::createOr(Op0NotVal, NotY);
4745 }
4746 }
Misha Brukmanb1c93172005-04-21 23:48:37 +00004747
Chris Lattner97638592003-07-23 21:37:07 +00004748 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
Chris Lattner5b2edb12006-02-12 08:02:11 +00004749 if (Op0I->getOpcode() == Instruction::Add) {
Chris Lattner0f68fa62003-11-04 23:37:10 +00004750 // ~(X-c) --> (-c-1)-X
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00004751 if (RHS->isAllOnesValue()) {
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00004752 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
4753 return BinaryOperator::createSub(
4754 ConstantExpr::getSub(NegOp0CI,
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00004755 ConstantInt::get(I.getType(), 1)),
Chris Lattner0f68fa62003-11-04 23:37:10 +00004756 Op0I->getOperand(0));
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00004757 }
Chris Lattnerf78df7c2006-02-26 19:57:54 +00004758 } else if (Op0I->getOpcode() == Instruction::Or) {
4759 // (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0
4760 if (MaskedValueIsZero(Op0I->getOperand(0), Op0CI->getZExtValue())) {
4761 Constant *NewRHS = ConstantExpr::getOr(Op0CI, RHS);
4762 // Anything in both C1 and C2 is known to be zero, remove it from
4763 // NewRHS.
4764 Constant *CommonBits = ConstantExpr::getAnd(Op0CI, RHS);
4765 NewRHS = ConstantExpr::getAnd(NewRHS,
4766 ConstantExpr::getNot(CommonBits));
Chris Lattnerb15e2b12007-03-02 21:28:56 +00004767 AddToWorkList(Op0I);
Chris Lattnerf78df7c2006-02-26 19:57:54 +00004768 I.setOperand(0, Op0I->getOperand(0));
4769 I.setOperand(1, NewRHS);
4770 return &I;
4771 }
Chris Lattner97638592003-07-23 21:37:07 +00004772 }
Chris Lattnerb8d6e402002-08-20 18:24:26 +00004773 }
Chris Lattner183b3362004-04-09 19:05:30 +00004774
4775 // Try to fold constant and into select arguments.
4776 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
Chris Lattner86102b82005-01-01 16:22:27 +00004777 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
Chris Lattner183b3362004-04-09 19:05:30 +00004778 return R;
Chris Lattner6a4adcd2004-09-29 05:07:12 +00004779 if (isa<PHINode>(Op0))
4780 if (Instruction *NV = FoldOpIntoPhi(I))
4781 return NV;
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00004782 }
4783
Chris Lattnerbb74e222003-03-10 23:06:50 +00004784 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
Chris Lattner3082c5a2003-02-18 19:28:33 +00004785 if (X == Op1)
4786 return ReplaceInstUsesWith(I,
Zhou Sheng75b871f2007-01-11 12:24:14 +00004787 ConstantInt::getAllOnesValue(I.getType()));
Chris Lattner3082c5a2003-02-18 19:28:33 +00004788
Chris Lattnerbb74e222003-03-10 23:06:50 +00004789 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
Chris Lattner3082c5a2003-02-18 19:28:33 +00004790 if (X == Op0)
Chris Lattner07418422007-03-18 22:51:34 +00004791 return ReplaceInstUsesWith(I, ConstantInt::getAllOnesValue(I.getType()));
Chris Lattner3082c5a2003-02-18 19:28:33 +00004792
Chris Lattner07418422007-03-18 22:51:34 +00004793
4794 BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1);
4795 if (Op1I) {
4796 Value *A, *B;
4797 if (match(Op1I, m_Or(m_Value(A), m_Value(B)))) {
4798 if (A == Op0) { // B^(B|A) == (A|B)^B
Chris Lattnerdcd07922006-04-01 08:03:55 +00004799 Op1I->swapOperands();
Chris Lattner1bbb7b62003-03-10 18:24:17 +00004800 I.swapOperands();
4801 std::swap(Op0, Op1);
Chris Lattner07418422007-03-18 22:51:34 +00004802 } else if (B == Op0) { // B^(A|B) == (A|B)^B
Chris Lattnerdcd07922006-04-01 08:03:55 +00004803 I.swapOperands(); // Simplified below.
Chris Lattner1bbb7b62003-03-10 18:24:17 +00004804 std::swap(Op0, Op1);
Misha Brukmanb1c93172005-04-21 23:48:37 +00004805 }
Chris Lattner07418422007-03-18 22:51:34 +00004806 } else if (match(Op1I, m_Xor(m_Value(A), m_Value(B)))) {
4807 if (Op0 == A) // A^(A^B) == B
4808 return ReplaceInstUsesWith(I, B);
4809 else if (Op0 == B) // A^(B^A) == B
4810 return ReplaceInstUsesWith(I, A);
4811 } else if (match(Op1I, m_And(m_Value(A), m_Value(B))) && Op1I->hasOneUse()){
4812 if (A == Op0) // A^(A&B) -> A^(B&A)
Chris Lattnerdcd07922006-04-01 08:03:55 +00004813 Op1I->swapOperands();
Chris Lattner07418422007-03-18 22:51:34 +00004814 if (B == Op0) { // A^(B&A) -> (B&A)^A
Chris Lattnerdcd07922006-04-01 08:03:55 +00004815 I.swapOperands(); // Simplified below.
4816 std::swap(Op0, Op1);
4817 }
Chris Lattnerb36d9082004-02-16 03:54:20 +00004818 }
Chris Lattner07418422007-03-18 22:51:34 +00004819 }
4820
4821 BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0);
4822 if (Op0I) {
4823 Value *A, *B;
4824 if (match(Op0I, m_Or(m_Value(A), m_Value(B))) && Op0I->hasOneUse()) {
4825 if (A == Op1) // (B|A)^B == (A|B)^B
4826 std::swap(A, B);
4827 if (B == Op1) { // (A|B)^B == A & ~B
4828 Instruction *NotB =
4829 InsertNewInstBefore(BinaryOperator::createNot(Op1, "tmp"), I);
4830 return BinaryOperator::createAnd(A, NotB);
Chris Lattner1bbb7b62003-03-10 18:24:17 +00004831 }
Chris Lattner07418422007-03-18 22:51:34 +00004832 } else if (match(Op0I, m_Xor(m_Value(A), m_Value(B)))) {
4833 if (Op1 == A) // (A^B)^A == B
4834 return ReplaceInstUsesWith(I, B);
4835 else if (Op1 == B) // (B^A)^A == B
4836 return ReplaceInstUsesWith(I, A);
4837 } else if (match(Op0I, m_And(m_Value(A), m_Value(B))) && Op0I->hasOneUse()){
4838 if (A == Op1) // (A&B)^A -> (B&A)^A
4839 std::swap(A, B);
4840 if (B == Op1 && // (B&A)^A == ~B & A
Chris Lattner6cf49142006-04-01 22:05:01 +00004841 !isa<ConstantInt>(Op1)) { // Canonical form is (B&C)^C
Chris Lattner07418422007-03-18 22:51:34 +00004842 Instruction *N =
4843 InsertNewInstBefore(BinaryOperator::createNot(A, "tmp"), I);
Chris Lattnerdcd07922006-04-01 08:03:55 +00004844 return BinaryOperator::createAnd(N, Op1);
4845 }
Chris Lattner1bbb7b62003-03-10 18:24:17 +00004846 }
Chris Lattner07418422007-03-18 22:51:34 +00004847 }
4848
4849 // (X >> Z) ^ (Y >> Z) -> (X^Y) >> Z for all shifts.
4850 if (Op0I && Op1I && Op0I->isShift() &&
4851 Op0I->getOpcode() == Op1I->getOpcode() &&
4852 Op0I->getOperand(1) == Op1I->getOperand(1) &&
4853 (Op1I->hasOneUse() || Op1I->hasOneUse())) {
4854 Instruction *NewOp =
4855 InsertNewInstBefore(BinaryOperator::createXor(Op0I->getOperand(0),
4856 Op1I->getOperand(0),
4857 Op0I->getName()), I);
4858 return BinaryOperator::create(Op1I->getOpcode(), NewOp,
4859 Op1I->getOperand(1));
4860 }
4861
4862 if (Op0I && Op1I) {
4863 Value *A, *B, *C, *D;
4864 // (A & B)^(A | B) -> A ^ B
4865 if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
4866 match(Op1I, m_Or(m_Value(C), m_Value(D)))) {
4867 if ((A == C && B == D) || (A == D && B == C))
4868 return BinaryOperator::createXor(A, B);
4869 }
4870 // (A | B)^(A & B) -> A ^ B
4871 if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
4872 match(Op1I, m_And(m_Value(C), m_Value(D)))) {
4873 if ((A == C && B == D) || (A == D && B == C))
4874 return BinaryOperator::createXor(A, B);
4875 }
4876
4877 // (A & B)^(C & D)
4878 if ((Op0I->hasOneUse() || Op1I->hasOneUse()) &&
4879 match(Op0I, m_And(m_Value(A), m_Value(B))) &&
4880 match(Op1I, m_And(m_Value(C), m_Value(D)))) {
4881 // (X & Y)^(X & Y) -> (Y^Z) & X
4882 Value *X = 0, *Y = 0, *Z = 0;
4883 if (A == C)
4884 X = A, Y = B, Z = D;
4885 else if (A == D)
4886 X = A, Y = B, Z = C;
4887 else if (B == C)
4888 X = B, Y = A, Z = D;
4889 else if (B == D)
4890 X = B, Y = A, Z = C;
4891
4892 if (X) {
4893 Instruction *NewOp =
4894 InsertNewInstBefore(BinaryOperator::createXor(Y, Z, Op0->getName()), I);
4895 return BinaryOperator::createAnd(NewOp, X);
4896 }
4897 }
4898 }
4899
Reid Spencer266e42b2006-12-23 06:05:41 +00004900 // (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B)
4901 if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1)))
4902 if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
Chris Lattner3ac7c262003-08-13 20:16:26 +00004903 return R;
4904
Chris Lattner3af10532006-05-05 06:39:07 +00004905 // fold (xor (cast A), (cast B)) -> (cast (xor A, B))
Reid Spencer799b5bf2006-12-13 08:27:15 +00004906 if (CastInst *Op0C = dyn_cast<CastInst>(Op0))
Chris Lattner3af10532006-05-05 06:39:07 +00004907 if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
Reid Spencer799b5bf2006-12-13 08:27:15 +00004908 if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind?
4909 const Type *SrcTy = Op0C->getOperand(0)->getType();
Chris Lattner03c49532007-01-15 02:27:26 +00004910 if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
Reid Spencer799b5bf2006-12-13 08:27:15 +00004911 // Only do this if the casts both really cause code to be generated.
Reid Spencer266e42b2006-12-23 06:05:41 +00004912 ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
4913 I.getType(), TD) &&
4914 ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
4915 I.getType(), TD)) {
Reid Spencer799b5bf2006-12-13 08:27:15 +00004916 Instruction *NewOp = BinaryOperator::createXor(Op0C->getOperand(0),
4917 Op1C->getOperand(0),
4918 I.getName());
4919 InsertNewInstBefore(NewOp, I);
4920 return CastInst::create(Op0C->getOpcode(), NewOp, I.getType());
4921 }
Chris Lattner3af10532006-05-05 06:39:07 +00004922 }
Chris Lattnerf05d69a2006-11-14 07:46:50 +00004923
Chris Lattner113f4f42002-06-25 16:13:24 +00004924 return Changed ? &I : 0;
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00004925}
4926
Chris Lattner6862fbd2004-09-29 17:40:11 +00004927/// AddWithOverflow - Compute Result = In1+In2, returning true if the result
4928/// overflowed for this type.
4929static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
4930 ConstantInt *In2) {
4931 Result = cast<ConstantInt>(ConstantExpr::getAdd(In1, In2));
4932
Reid Spencerc635f472006-12-31 05:48:39 +00004933 return cast<ConstantInt>(Result)->getZExtValue() <
4934 cast<ConstantInt>(In1)->getZExtValue();
Chris Lattner6862fbd2004-09-29 17:40:11 +00004935}
4936
Chris Lattner0798af32005-01-13 20:14:25 +00004937/// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
4938/// code necessary to compute the offset from the base pointer (without adding
4939/// in the base pointer). Return the result as a signed integer of intptr size.
4940static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) {
4941 TargetData &TD = IC.getTargetData();
4942 gep_type_iterator GTI = gep_type_begin(GEP);
Reid Spencer266e42b2006-12-23 06:05:41 +00004943 const Type *IntPtrTy = TD.getIntPtrType();
4944 Value *Result = Constant::getNullValue(IntPtrTy);
Chris Lattner0798af32005-01-13 20:14:25 +00004945
4946 // Build a mask for high order bits.
Chris Lattner77defba2006-02-07 07:00:41 +00004947 uint64_t PtrSizeMask = ~0ULL >> (64-TD.getPointerSize()*8);
Chris Lattner0798af32005-01-13 20:14:25 +00004948
Chris Lattner0798af32005-01-13 20:14:25 +00004949 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
4950 Value *Op = GEP->getOperand(i);
Chris Lattnerd35d2102005-01-13 23:26:48 +00004951 uint64_t Size = TD.getTypeSize(GTI.getIndexedType()) & PtrSizeMask;
Reid Spencer266e42b2006-12-23 06:05:41 +00004952 Constant *Scale = ConstantInt::get(IntPtrTy, Size);
Chris Lattner0798af32005-01-13 20:14:25 +00004953 if (Constant *OpC = dyn_cast<Constant>(Op)) {
4954 if (!OpC->isNullValue()) {
Reid Spencer266e42b2006-12-23 06:05:41 +00004955 OpC = ConstantExpr::getIntegerCast(OpC, IntPtrTy, true /*SExt*/);
Chris Lattner0798af32005-01-13 20:14:25 +00004956 Scale = ConstantExpr::getMul(OpC, Scale);
4957 if (Constant *RC = dyn_cast<Constant>(Result))
4958 Result = ConstantExpr::getAdd(RC, Scale);
4959 else {
4960 // Emit an add instruction.
4961 Result = IC.InsertNewInstBefore(
4962 BinaryOperator::createAdd(Result, Scale,
4963 GEP->getName()+".offs"), I);
4964 }
4965 }
4966 } else {
Chris Lattner7aa41cf2005-01-14 17:17:59 +00004967 // Convert to correct type.
Reid Spencer266e42b2006-12-23 06:05:41 +00004968 Op = IC.InsertNewInstBefore(CastInst::createSExtOrBitCast(Op, IntPtrTy,
Chris Lattner7aa41cf2005-01-14 17:17:59 +00004969 Op->getName()+".c"), I);
4970 if (Size != 1)
Chris Lattner4cb9fa32005-01-13 20:40:58 +00004971 // We'll let instcombine(mul) convert this to a shl if possible.
4972 Op = IC.InsertNewInstBefore(BinaryOperator::createMul(Op, Scale,
4973 GEP->getName()+".idx"), I);
Chris Lattner0798af32005-01-13 20:14:25 +00004974
4975 // Emit an add instruction.
Chris Lattner4cb9fa32005-01-13 20:40:58 +00004976 Result = IC.InsertNewInstBefore(BinaryOperator::createAdd(Op, Result,
Chris Lattner0798af32005-01-13 20:14:25 +00004977 GEP->getName()+".offs"), I);
4978 }
4979 }
4980 return Result;
4981}
4982
Reid Spencer266e42b2006-12-23 06:05:41 +00004983/// FoldGEPICmp - Fold comparisons between a GEP instruction and something
Chris Lattner0798af32005-01-13 20:14:25 +00004984/// else. At this point we know that the GEP is on the LHS of the comparison.
Reid Spencer266e42b2006-12-23 06:05:41 +00004985Instruction *InstCombiner::FoldGEPICmp(User *GEPLHS, Value *RHS,
4986 ICmpInst::Predicate Cond,
4987 Instruction &I) {
Chris Lattner0798af32005-01-13 20:14:25 +00004988 assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!");
Chris Lattner81e84172005-01-13 22:25:21 +00004989
4990 if (CastInst *CI = dyn_cast<CastInst>(RHS))
4991 if (isa<PointerType>(CI->getOperand(0)->getType()))
4992 RHS = CI->getOperand(0);
4993
Chris Lattner0798af32005-01-13 20:14:25 +00004994 Value *PtrBase = GEPLHS->getOperand(0);
4995 if (PtrBase == RHS) {
4996 // As an optimization, we don't actually have to compute the actual value of
Reid Spencer266e42b2006-12-23 06:05:41 +00004997 // OFFSET if this is a icmp_eq or icmp_ne comparison, just return whether
4998 // each index is zero or not.
4999 if (Cond == ICmpInst::ICMP_EQ || Cond == ICmpInst::ICMP_NE) {
Chris Lattner81e84172005-01-13 22:25:21 +00005000 Instruction *InVal = 0;
Chris Lattnercd517ff2005-01-28 19:32:01 +00005001 gep_type_iterator GTI = gep_type_begin(GEPLHS);
5002 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i, ++GTI) {
Chris Lattner81e84172005-01-13 22:25:21 +00005003 bool EmitIt = true;
5004 if (Constant *C = dyn_cast<Constant>(GEPLHS->getOperand(i))) {
5005 if (isa<UndefValue>(C)) // undef index -> undef.
5006 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
5007 if (C->isNullValue())
5008 EmitIt = false;
Chris Lattnercd517ff2005-01-28 19:32:01 +00005009 else if (TD->getTypeSize(GTI.getIndexedType()) == 0) {
5010 EmitIt = false; // This is indexing into a zero sized array?
Misha Brukmanb1c93172005-04-21 23:48:37 +00005011 } else if (isa<ConstantInt>(C))
Chris Lattner81e84172005-01-13 22:25:21 +00005012 return ReplaceInstUsesWith(I, // No comparison is needed here.
Reid Spencercddc9df2007-01-12 04:24:46 +00005013 ConstantInt::get(Type::Int1Ty,
5014 Cond == ICmpInst::ICMP_NE));
Chris Lattner81e84172005-01-13 22:25:21 +00005015 }
5016
5017 if (EmitIt) {
Misha Brukmanb1c93172005-04-21 23:48:37 +00005018 Instruction *Comp =
Reid Spencer266e42b2006-12-23 06:05:41 +00005019 new ICmpInst(Cond, GEPLHS->getOperand(i),
Chris Lattner81e84172005-01-13 22:25:21 +00005020 Constant::getNullValue(GEPLHS->getOperand(i)->getType()));
5021 if (InVal == 0)
5022 InVal = Comp;
5023 else {
5024 InVal = InsertNewInstBefore(InVal, I);
5025 InsertNewInstBefore(Comp, I);
Reid Spencer266e42b2006-12-23 06:05:41 +00005026 if (Cond == ICmpInst::ICMP_NE) // True if any are unequal
Chris Lattner81e84172005-01-13 22:25:21 +00005027 InVal = BinaryOperator::createOr(InVal, Comp);
5028 else // True if all are equal
5029 InVal = BinaryOperator::createAnd(InVal, Comp);
5030 }
5031 }
5032 }
5033
5034 if (InVal)
5035 return InVal;
5036 else
Reid Spencer266e42b2006-12-23 06:05:41 +00005037 // No comparison is needed here, all indexes = 0
Reid Spencercddc9df2007-01-12 04:24:46 +00005038 ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
5039 Cond == ICmpInst::ICMP_EQ));
Chris Lattner81e84172005-01-13 22:25:21 +00005040 }
Chris Lattner0798af32005-01-13 20:14:25 +00005041
Reid Spencer266e42b2006-12-23 06:05:41 +00005042 // Only lower this if the icmp is the only user of the GEP or if we expect
Chris Lattner0798af32005-01-13 20:14:25 +00005043 // the result to fold to a constant!
5044 if (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) {
5045 // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
5046 Value *Offset = EmitGEPOffset(GEPLHS, I, *this);
Reid Spencer266e42b2006-12-23 06:05:41 +00005047 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset,
5048 Constant::getNullValue(Offset->getType()));
Chris Lattner0798af32005-01-13 20:14:25 +00005049 }
5050 } else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) {
Chris Lattnera21bf8d2005-04-25 20:17:30 +00005051 // If the base pointers are different, but the indices are the same, just
5052 // compare the base pointer.
5053 if (PtrBase != GEPRHS->getOperand(0)) {
5054 bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
Jeff Cohen5f4ef3c2005-07-27 06:12:32 +00005055 IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
Chris Lattnerbd43b9d2005-04-26 14:40:41 +00005056 GEPRHS->getOperand(0)->getType();
Chris Lattnera21bf8d2005-04-25 20:17:30 +00005057 if (IndicesTheSame)
5058 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
5059 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
5060 IndicesTheSame = false;
5061 break;
5062 }
5063
5064 // If all indices are the same, just compare the base pointers.
5065 if (IndicesTheSame)
Reid Spencer266e42b2006-12-23 06:05:41 +00005066 return new ICmpInst(ICmpInst::getSignedPredicate(Cond),
5067 GEPLHS->getOperand(0), GEPRHS->getOperand(0));
Chris Lattnera21bf8d2005-04-25 20:17:30 +00005068
5069 // Otherwise, the base pointers are different and the indices are
5070 // different, bail out.
Chris Lattner0798af32005-01-13 20:14:25 +00005071 return 0;
Chris Lattnera21bf8d2005-04-25 20:17:30 +00005072 }
Chris Lattner0798af32005-01-13 20:14:25 +00005073
Chris Lattner81e84172005-01-13 22:25:21 +00005074 // If one of the GEPs has all zero indices, recurse.
5075 bool AllZeros = true;
5076 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
5077 if (!isa<Constant>(GEPLHS->getOperand(i)) ||
5078 !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
5079 AllZeros = false;
5080 break;
5081 }
5082 if (AllZeros)
Reid Spencer266e42b2006-12-23 06:05:41 +00005083 return FoldGEPICmp(GEPRHS, GEPLHS->getOperand(0),
5084 ICmpInst::getSwappedPredicate(Cond), I);
Chris Lattner4fa89822005-01-14 00:20:05 +00005085
5086 // If the other GEP has all zero indices, recurse.
Chris Lattner81e84172005-01-13 22:25:21 +00005087 AllZeros = true;
5088 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
5089 if (!isa<Constant>(GEPRHS->getOperand(i)) ||
5090 !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
5091 AllZeros = false;
5092 break;
5093 }
5094 if (AllZeros)
Reid Spencer266e42b2006-12-23 06:05:41 +00005095 return FoldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I);
Chris Lattner81e84172005-01-13 22:25:21 +00005096
Chris Lattner4fa89822005-01-14 00:20:05 +00005097 if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
5098 // If the GEPs only differ by one index, compare it.
5099 unsigned NumDifferences = 0; // Keep track of # differences.
5100 unsigned DiffOperand = 0; // The operand that differs.
5101 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
5102 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
Chris Lattnerd1f46d32005-04-24 06:59:08 +00005103 if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
5104 GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
Chris Lattnerfc4429e2005-01-21 23:06:49 +00005105 // Irreconcilable differences.
Chris Lattner4fa89822005-01-14 00:20:05 +00005106 NumDifferences = 2;
5107 break;
5108 } else {
5109 if (NumDifferences++) break;
5110 DiffOperand = i;
5111 }
5112 }
5113
5114 if (NumDifferences == 0) // SAME GEP?
5115 return ReplaceInstUsesWith(I, // No comparison is needed here.
Reid Spencercddc9df2007-01-12 04:24:46 +00005116 ConstantInt::get(Type::Int1Ty,
5117 Cond == ICmpInst::ICMP_EQ));
Chris Lattner4fa89822005-01-14 00:20:05 +00005118 else if (NumDifferences == 1) {
Chris Lattnerfc4429e2005-01-21 23:06:49 +00005119 Value *LHSV = GEPLHS->getOperand(DiffOperand);
5120 Value *RHSV = GEPRHS->getOperand(DiffOperand);
Reid Spencer266e42b2006-12-23 06:05:41 +00005121 // Make sure we do a signed comparison here.
5122 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV);
Chris Lattner4fa89822005-01-14 00:20:05 +00005123 }
5124 }
5125
Reid Spencer266e42b2006-12-23 06:05:41 +00005126 // Only lower this if the icmp is the only user of the GEP or if we expect
Chris Lattner0798af32005-01-13 20:14:25 +00005127 // the result to fold to a constant!
5128 if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
5129 (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
5130 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
5131 Value *L = EmitGEPOffset(GEPLHS, I, *this);
5132 Value *R = EmitGEPOffset(GEPRHS, I, *this);
Reid Spencer266e42b2006-12-23 06:05:41 +00005133 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R);
Chris Lattner0798af32005-01-13 20:14:25 +00005134 }
5135 }
5136 return 0;
5137}
5138
Reid Spencer266e42b2006-12-23 06:05:41 +00005139Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
5140 bool Changed = SimplifyCompare(I);
Chris Lattner6d14f2a2002-08-09 23:47:40 +00005141 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00005142
Chris Lattner6ee923f2007-01-14 19:42:17 +00005143 // Fold trivial predicates.
5144 if (I.getPredicate() == FCmpInst::FCMP_FALSE)
5145 return ReplaceInstUsesWith(I, Constant::getNullValue(Type::Int1Ty));
5146 if (I.getPredicate() == FCmpInst::FCMP_TRUE)
5147 return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, 1));
5148
5149 // Simplify 'fcmp pred X, X'
5150 if (Op0 == Op1) {
5151 switch (I.getPredicate()) {
5152 default: assert(0 && "Unknown predicate!");
5153 case FCmpInst::FCMP_UEQ: // True if unordered or equal
5154 case FCmpInst::FCMP_UGE: // True if unordered, greater than, or equal
5155 case FCmpInst::FCMP_ULE: // True if unordered, less than, or equal
5156 return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, 1));
5157 case FCmpInst::FCMP_OGT: // True if ordered and greater than
5158 case FCmpInst::FCMP_OLT: // True if ordered and less than
5159 case FCmpInst::FCMP_ONE: // True if ordered and operands are unequal
5160 return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, 0));
5161
5162 case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y)
5163 case FCmpInst::FCMP_ULT: // True if unordered or less than
5164 case FCmpInst::FCMP_UGT: // True if unordered or greater than
5165 case FCmpInst::FCMP_UNE: // True if unordered or not equal
5166 // Canonicalize these to be 'fcmp uno %X, 0.0'.
5167 I.setPredicate(FCmpInst::FCMP_UNO);
5168 I.setOperand(1, Constant::getNullValue(Op0->getType()));
5169 return &I;
5170
5171 case FCmpInst::FCMP_ORD: // True if ordered (no nans)
5172 case FCmpInst::FCMP_OEQ: // True if ordered and equal
5173 case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal
5174 case FCmpInst::FCMP_OLE: // True if ordered and less than or equal
5175 // Canonicalize these to be 'fcmp ord %X, 0.0'.
5176 I.setPredicate(FCmpInst::FCMP_ORD);
5177 I.setOperand(1, Constant::getNullValue(Op0->getType()));
5178 return &I;
5179 }
5180 }
5181
Reid Spencer266e42b2006-12-23 06:05:41 +00005182 if (isa<UndefValue>(Op1)) // fcmp pred X, undef -> undef
Reid Spencer542964f2007-01-11 18:21:29 +00005183 return ReplaceInstUsesWith(I, UndefValue::get(Type::Int1Ty));
Chris Lattner81a7a232004-10-16 18:11:37 +00005184
Reid Spencer266e42b2006-12-23 06:05:41 +00005185 // Handle fcmp with constant RHS
5186 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
5187 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
5188 switch (LHSI->getOpcode()) {
5189 case Instruction::PHI:
5190 if (Instruction *NV = FoldOpIntoPhi(I))
5191 return NV;
5192 break;
5193 case Instruction::Select:
5194 // If either operand of the select is a constant, we can fold the
5195 // comparison into the select arms, which will cause one to be
5196 // constant folded and the select turned into a bitwise or.
5197 Value *Op1 = 0, *Op2 = 0;
5198 if (LHSI->hasOneUse()) {
5199 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
5200 // Fold the known value into the constant operand.
5201 Op1 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
5202 // Insert a new FCmp of the other select operand.
5203 Op2 = InsertNewInstBefore(new FCmpInst(I.getPredicate(),
5204 LHSI->getOperand(2), RHSC,
5205 I.getName()), I);
5206 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
5207 // Fold the known value into the constant operand.
5208 Op2 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
5209 // Insert a new FCmp of the other select operand.
5210 Op1 = InsertNewInstBefore(new FCmpInst(I.getPredicate(),
5211 LHSI->getOperand(1), RHSC,
5212 I.getName()), I);
5213 }
5214 }
5215
5216 if (Op1)
5217 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
5218 break;
5219 }
5220 }
5221
5222 return Changed ? &I : 0;
5223}
5224
5225Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
5226 bool Changed = SimplifyCompare(I);
5227 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
5228 const Type *Ty = Op0->getType();
5229
5230 // icmp X, X
5231 if (Op0 == Op1)
Reid Spencercddc9df2007-01-12 04:24:46 +00005232 return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
5233 isTrueWhenEqual(I)));
Reid Spencer266e42b2006-12-23 06:05:41 +00005234
5235 if (isa<UndefValue>(Op1)) // X icmp undef -> undef
Reid Spencer542964f2007-01-11 18:21:29 +00005236 return ReplaceInstUsesWith(I, UndefValue::get(Type::Int1Ty));
Reid Spencer266e42b2006-12-23 06:05:41 +00005237
5238 // icmp of GlobalValues can never equal each other as long as they aren't
5239 // external weak linkage type.
5240 if (GlobalValue *GV0 = dyn_cast<GlobalValue>(Op0))
5241 if (GlobalValue *GV1 = dyn_cast<GlobalValue>(Op1))
5242 if (!GV0->hasExternalWeakLinkage() || !GV1->hasExternalWeakLinkage())
Reid Spencercddc9df2007-01-12 04:24:46 +00005243 return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
5244 !isTrueWhenEqual(I)));
Reid Spencer266e42b2006-12-23 06:05:41 +00005245
5246 // icmp <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
Chris Lattner15ff1e12004-11-14 07:33:16 +00005247 // addresses never equal each other! We already know that Op0 != Op1.
Misha Brukmanb1c93172005-04-21 23:48:37 +00005248 if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||
5249 isa<ConstantPointerNull>(Op0)) &&
5250 (isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) ||
Chris Lattner15ff1e12004-11-14 07:33:16 +00005251 isa<ConstantPointerNull>(Op1)))
Reid Spencercddc9df2007-01-12 04:24:46 +00005252 return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
5253 !isTrueWhenEqual(I)));
Chris Lattner6d14f2a2002-08-09 23:47:40 +00005254
Reid Spencer266e42b2006-12-23 06:05:41 +00005255 // icmp's with boolean values can always be turned into bitwise operations
Reid Spencer542964f2007-01-11 18:21:29 +00005256 if (Ty == Type::Int1Ty) {
Reid Spencer266e42b2006-12-23 06:05:41 +00005257 switch (I.getPredicate()) {
5258 default: assert(0 && "Invalid icmp instruction!");
5259 case ICmpInst::ICMP_EQ: { // icmp eq bool %A, %B -> ~(A^B)
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00005260 Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp");
Chris Lattner6d14f2a2002-08-09 23:47:40 +00005261 InsertNewInstBefore(Xor, I);
Chris Lattner16930792003-11-03 04:25:02 +00005262 return BinaryOperator::createNot(Xor);
Chris Lattner6d14f2a2002-08-09 23:47:40 +00005263 }
Reid Spencer266e42b2006-12-23 06:05:41 +00005264 case ICmpInst::ICMP_NE: // icmp eq bool %A, %B -> A^B
Chris Lattner4456da62004-08-11 00:50:51 +00005265 return BinaryOperator::createXor(Op0, Op1);
Chris Lattner6d14f2a2002-08-09 23:47:40 +00005266
Reid Spencer266e42b2006-12-23 06:05:41 +00005267 case ICmpInst::ICMP_UGT:
5268 case ICmpInst::ICMP_SGT:
5269 std::swap(Op0, Op1); // Change icmp gt -> icmp lt
Chris Lattner4456da62004-08-11 00:50:51 +00005270 // FALL THROUGH
Reid Spencer266e42b2006-12-23 06:05:41 +00005271 case ICmpInst::ICMP_ULT:
5272 case ICmpInst::ICMP_SLT: { // icmp lt bool A, B -> ~X & Y
Chris Lattner4456da62004-08-11 00:50:51 +00005273 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
5274 InsertNewInstBefore(Not, I);
5275 return BinaryOperator::createAnd(Not, Op1);
5276 }
Reid Spencer266e42b2006-12-23 06:05:41 +00005277 case ICmpInst::ICMP_UGE:
5278 case ICmpInst::ICMP_SGE:
5279 std::swap(Op0, Op1); // Change icmp ge -> icmp le
Chris Lattner4456da62004-08-11 00:50:51 +00005280 // FALL THROUGH
Reid Spencer266e42b2006-12-23 06:05:41 +00005281 case ICmpInst::ICMP_ULE:
5282 case ICmpInst::ICMP_SLE: { // icmp le bool %A, %B -> ~A | B
Chris Lattner4456da62004-08-11 00:50:51 +00005283 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
5284 InsertNewInstBefore(Not, I);
5285 return BinaryOperator::createOr(Not, Op1);
5286 }
5287 }
Chris Lattner6d14f2a2002-08-09 23:47:40 +00005288 }
5289
Chris Lattner2dd01742004-06-09 04:24:29 +00005290 // See if we are doing a comparison between a constant and an instruction that
5291 // can be folded into the comparison.
Chris Lattner6d14f2a2002-08-09 23:47:40 +00005292 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
Reid Spencer266e42b2006-12-23 06:05:41 +00005293 switch (I.getPredicate()) {
5294 default: break;
5295 case ICmpInst::ICMP_ULT: // A <u MIN -> FALSE
5296 if (CI->isMinValue(false))
Zhou Sheng75b871f2007-01-11 12:24:14 +00005297 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
Reid Spencer266e42b2006-12-23 06:05:41 +00005298 if (CI->isMaxValue(false)) // A <u MAX -> A != MAX
5299 return new ICmpInst(ICmpInst::ICMP_NE, Op0,Op1);
5300 if (isMinValuePlusOne(CI,false)) // A <u MIN+1 -> A == MIN
5301 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, SubOne(CI));
5302 break;
Chris Lattner6862fbd2004-09-29 17:40:11 +00005303
Reid Spencer266e42b2006-12-23 06:05:41 +00005304 case ICmpInst::ICMP_SLT:
5305 if (CI->isMinValue(true)) // A <s MIN -> FALSE
Zhou Sheng75b871f2007-01-11 12:24:14 +00005306 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
Reid Spencer266e42b2006-12-23 06:05:41 +00005307 if (CI->isMaxValue(true)) // A <s MAX -> A != MAX
5308 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
5309 if (isMinValuePlusOne(CI,true)) // A <s MIN+1 -> A == MIN
5310 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, SubOne(CI));
5311 break;
5312
5313 case ICmpInst::ICMP_UGT:
5314 if (CI->isMaxValue(false)) // A >u MAX -> FALSE
Zhou Sheng75b871f2007-01-11 12:24:14 +00005315 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
Reid Spencer266e42b2006-12-23 06:05:41 +00005316 if (CI->isMinValue(false)) // A >u MIN -> A != MIN
5317 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
5318 if (isMaxValueMinusOne(CI, false)) // A >u MAX-1 -> A == MAX
5319 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, AddOne(CI));
5320 break;
5321
5322 case ICmpInst::ICMP_SGT:
5323 if (CI->isMaxValue(true)) // A >s MAX -> FALSE
Zhou Sheng75b871f2007-01-11 12:24:14 +00005324 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
Reid Spencer266e42b2006-12-23 06:05:41 +00005325 if (CI->isMinValue(true)) // A >s MIN -> A != MIN
5326 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
5327 if (isMaxValueMinusOne(CI, true)) // A >s MAX-1 -> A == MAX
5328 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, AddOne(CI));
5329 break;
5330
5331 case ICmpInst::ICMP_ULE:
5332 if (CI->isMaxValue(false)) // A <=u MAX -> TRUE
Zhou Sheng75b871f2007-01-11 12:24:14 +00005333 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
Reid Spencer266e42b2006-12-23 06:05:41 +00005334 if (CI->isMinValue(false)) // A <=u MIN -> A == MIN
5335 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
5336 if (isMaxValueMinusOne(CI,false)) // A <=u MAX-1 -> A != MAX
5337 return new ICmpInst(ICmpInst::ICMP_NE, Op0, AddOne(CI));
5338 break;
Chris Lattner6862fbd2004-09-29 17:40:11 +00005339
Reid Spencer266e42b2006-12-23 06:05:41 +00005340 case ICmpInst::ICMP_SLE:
5341 if (CI->isMaxValue(true)) // A <=s MAX -> TRUE
Zhou Sheng75b871f2007-01-11 12:24:14 +00005342 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
Reid Spencer266e42b2006-12-23 06:05:41 +00005343 if (CI->isMinValue(true)) // A <=s MIN -> A == MIN
5344 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
5345 if (isMaxValueMinusOne(CI,true)) // A <=s MAX-1 -> A != MAX
5346 return new ICmpInst(ICmpInst::ICMP_NE, Op0, AddOne(CI));
5347 break;
Chris Lattner6862fbd2004-09-29 17:40:11 +00005348
Reid Spencer266e42b2006-12-23 06:05:41 +00005349 case ICmpInst::ICMP_UGE:
5350 if (CI->isMinValue(false)) // A >=u MIN -> TRUE
Zhou Sheng75b871f2007-01-11 12:24:14 +00005351 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
Reid Spencer266e42b2006-12-23 06:05:41 +00005352 if (CI->isMaxValue(false)) // A >=u MAX -> A == MAX
5353 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
5354 if (isMinValuePlusOne(CI,false)) // A >=u MIN-1 -> A != MIN
5355 return new ICmpInst(ICmpInst::ICMP_NE, Op0, SubOne(CI));
5356 break;
5357
5358 case ICmpInst::ICMP_SGE:
5359 if (CI->isMinValue(true)) // A >=s MIN -> TRUE
Zhou Sheng75b871f2007-01-11 12:24:14 +00005360 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
Reid Spencer266e42b2006-12-23 06:05:41 +00005361 if (CI->isMaxValue(true)) // A >=s MAX -> A == MAX
5362 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
5363 if (isMinValuePlusOne(CI,true)) // A >=s MIN-1 -> A != MIN
5364 return new ICmpInst(ICmpInst::ICMP_NE, Op0, SubOne(CI));
5365 break;
Chris Lattner6862fbd2004-09-29 17:40:11 +00005366 }
5367
Reid Spencer266e42b2006-12-23 06:05:41 +00005368 // If we still have a icmp le or icmp ge instruction, turn it into the
5369 // appropriate icmp lt or icmp gt instruction. Since the border cases have
Chris Lattner6862fbd2004-09-29 17:40:11 +00005370 // already been handled above, this requires little checking.
5371 //
Reid Spencer266e42b2006-12-23 06:05:41 +00005372 if (I.getPredicate() == ICmpInst::ICMP_ULE)
5373 return new ICmpInst(ICmpInst::ICMP_ULT, Op0, AddOne(CI));
5374 if (I.getPredicate() == ICmpInst::ICMP_SLE)
5375 return new ICmpInst(ICmpInst::ICMP_SLT, Op0, AddOne(CI));
5376 if (I.getPredicate() == ICmpInst::ICMP_UGE)
5377 return new ICmpInst( ICmpInst::ICMP_UGT, Op0, SubOne(CI));
5378 if (I.getPredicate() == ICmpInst::ICMP_SGE)
5379 return new ICmpInst(ICmpInst::ICMP_SGT, Op0, SubOne(CI));
Chris Lattneree0f2802006-02-12 02:07:56 +00005380
5381 // See if we can fold the comparison based on bits known to be zero or one
5382 // in the input.
5383 uint64_t KnownZero, KnownOne;
Reid Spencera94d3942007-01-19 21:13:56 +00005384 if (SimplifyDemandedBits(Op0, cast<IntegerType>(Ty)->getBitMask(),
Chris Lattneree0f2802006-02-12 02:07:56 +00005385 KnownZero, KnownOne, 0))
5386 return &I;
5387
5388 // Given the known and unknown bits, compute a range that the LHS could be
5389 // in.
5390 if (KnownOne | KnownZero) {
Reid Spencer266e42b2006-12-23 06:05:41 +00005391 // Compute the Min, Max and RHS values based on the known bits. For the
5392 // EQ and NE we use unsigned values.
Reid Spencer910f23f2006-12-23 19:17:57 +00005393 uint64_t UMin = 0, UMax = 0, URHSVal = 0;
5394 int64_t SMin = 0, SMax = 0, SRHSVal = 0;
Reid Spencer266e42b2006-12-23 06:05:41 +00005395 if (ICmpInst::isSignedPredicate(I.getPredicate())) {
5396 SRHSVal = CI->getSExtValue();
5397 ComputeSignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne, SMin,
5398 SMax);
5399 } else {
5400 URHSVal = CI->getZExtValue();
5401 ComputeUnsignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne, UMin,
5402 UMax);
5403 }
5404 switch (I.getPredicate()) { // LE/GE have been folded already.
5405 default: assert(0 && "Unknown icmp opcode!");
5406 case ICmpInst::ICMP_EQ:
5407 if (UMax < URHSVal || UMin > URHSVal)
Zhou Sheng75b871f2007-01-11 12:24:14 +00005408 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
Reid Spencer266e42b2006-12-23 06:05:41 +00005409 break;
5410 case ICmpInst::ICMP_NE:
5411 if (UMax < URHSVal || UMin > URHSVal)
Zhou Sheng75b871f2007-01-11 12:24:14 +00005412 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
Reid Spencer266e42b2006-12-23 06:05:41 +00005413 break;
5414 case ICmpInst::ICMP_ULT:
5415 if (UMax < URHSVal)
Zhou Sheng75b871f2007-01-11 12:24:14 +00005416 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
Reid Spencer266e42b2006-12-23 06:05:41 +00005417 if (UMin > URHSVal)
Zhou Sheng75b871f2007-01-11 12:24:14 +00005418 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
Reid Spencer266e42b2006-12-23 06:05:41 +00005419 break;
5420 case ICmpInst::ICMP_UGT:
5421 if (UMin > URHSVal)
Zhou Sheng75b871f2007-01-11 12:24:14 +00005422 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
Reid Spencer266e42b2006-12-23 06:05:41 +00005423 if (UMax < URHSVal)
Zhou Sheng75b871f2007-01-11 12:24:14 +00005424 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
Reid Spencer266e42b2006-12-23 06:05:41 +00005425 break;
5426 case ICmpInst::ICMP_SLT:
5427 if (SMax < SRHSVal)
Zhou Sheng75b871f2007-01-11 12:24:14 +00005428 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
Reid Spencer266e42b2006-12-23 06:05:41 +00005429 if (SMin > SRHSVal)
Zhou Sheng75b871f2007-01-11 12:24:14 +00005430 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
Reid Spencer266e42b2006-12-23 06:05:41 +00005431 break;
5432 case ICmpInst::ICMP_SGT:
5433 if (SMin > SRHSVal)
Zhou Sheng75b871f2007-01-11 12:24:14 +00005434 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
Reid Spencer266e42b2006-12-23 06:05:41 +00005435 if (SMax < SRHSVal)
Zhou Sheng75b871f2007-01-11 12:24:14 +00005436 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
Reid Spencer266e42b2006-12-23 06:05:41 +00005437 break;
Chris Lattneree0f2802006-02-12 02:07:56 +00005438 }
5439 }
5440
Reid Spencer266e42b2006-12-23 06:05:41 +00005441 // Since the RHS is a ConstantInt (CI), if the left hand side is an
Reid Spencer7e80b0b2006-10-26 06:15:43 +00005442 // instruction, see if that instruction also has constants so that the
Reid Spencer266e42b2006-12-23 06:05:41 +00005443 // instruction can be folded into the icmp
Chris Lattnere1e10e12004-05-25 06:32:08 +00005444 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
Chris Lattnere1b4d2a2004-09-23 21:52:49 +00005445 switch (LHSI->getOpcode()) {
5446 case Instruction::And:
5447 if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
5448 LHSI->getOperand(0)->hasOneUse()) {
Chris Lattner4922a0e2006-09-18 05:27:43 +00005449 ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
5450
Reid Spencer266e42b2006-12-23 06:05:41 +00005451 // If the LHS is an AND of a truncating cast, we can widen the
Chris Lattner4922a0e2006-09-18 05:27:43 +00005452 // and/compare to be the input width without changing the value
5453 // produced, eliminating a cast.
5454 if (CastInst *Cast = dyn_cast<CastInst>(LHSI->getOperand(0))) {
5455 // We can do this transformation if either the AND constant does not
5456 // have its sign bit set or if it is an equality comparison.
5457 // Extending a relational comparison when we're checking the sign
5458 // bit would not work.
Reid Spencer6c38f0b2006-11-27 01:05:10 +00005459 if (Cast->hasOneUse() && isa<TruncInst>(Cast) &&
Chris Lattner4922a0e2006-09-18 05:27:43 +00005460 (I.isEquality() ||
5461 (AndCST->getZExtValue() == (uint64_t)AndCST->getSExtValue()) &&
5462 (CI->getZExtValue() == (uint64_t)CI->getSExtValue()))) {
5463 ConstantInt *NewCST;
5464 ConstantInt *NewCI;
Reid Spencerc635f472006-12-31 05:48:39 +00005465 NewCST = ConstantInt::get(Cast->getOperand(0)->getType(),
5466 AndCST->getZExtValue());
5467 NewCI = ConstantInt::get(Cast->getOperand(0)->getType(),
5468 CI->getZExtValue());
Chris Lattner4922a0e2006-09-18 05:27:43 +00005469 Instruction *NewAnd =
5470 BinaryOperator::createAnd(Cast->getOperand(0), NewCST,
5471 LHSI->getName());
5472 InsertNewInstBefore(NewAnd, I);
Reid Spencer266e42b2006-12-23 06:05:41 +00005473 return new ICmpInst(I.getPredicate(), NewAnd, NewCI);
Chris Lattner4922a0e2006-09-18 05:27:43 +00005474 }
5475 }
5476
Chris Lattnere1b4d2a2004-09-23 21:52:49 +00005477 // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
5478 // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
5479 // happens a LOT in code produced by the C front-end, for bitfield
5480 // access.
Reid Spencer2341c222007-02-02 02:16:23 +00005481 BinaryOperator *Shift = dyn_cast<BinaryOperator>(LHSI->getOperand(0));
5482 if (Shift && !Shift->isShift())
5483 Shift = 0;
Chris Lattneree0f2802006-02-12 02:07:56 +00005484
Reid Spencere0fc4df2006-10-20 07:07:24 +00005485 ConstantInt *ShAmt;
5486 ShAmt = Shift ? dyn_cast<ConstantInt>(Shift->getOperand(1)) : 0;
Chris Lattneree0f2802006-02-12 02:07:56 +00005487 const Type *Ty = Shift ? Shift->getType() : 0; // Type of the shift.
5488 const Type *AndTy = AndCST->getType(); // Type of the and.
Misha Brukmanb1c93172005-04-21 23:48:37 +00005489
Chris Lattnere1b4d2a2004-09-23 21:52:49 +00005490 // We can fold this as long as we can't shift unknown bits
5491 // into the mask. This can only happen with signed shift
5492 // rights, as they sign-extend.
5493 if (ShAmt) {
Chris Lattnerb3f24c92006-09-18 04:22:48 +00005494 bool CanFold = Shift->isLogicalShift();
Chris Lattnere1b4d2a2004-09-23 21:52:49 +00005495 if (!CanFold) {
5496 // To test for the bad case of the signed shr, see if any
5497 // of the bits shifted in could be tested after the mask.
Reid Spencere0fc4df2006-10-20 07:07:24 +00005498 int ShAmtVal = Ty->getPrimitiveSizeInBits()-ShAmt->getZExtValue();
Chris Lattnerc53cb9d2005-06-17 01:29:28 +00005499 if (ShAmtVal < 0) ShAmtVal = 0; // Out of range shift.
5500
Reid Spencer2341c222007-02-02 02:16:23 +00005501 Constant *OShAmt = ConstantInt::get(AndTy, ShAmtVal);
Misha Brukmanb1c93172005-04-21 23:48:37 +00005502 Constant *ShVal =
Chris Lattneree0f2802006-02-12 02:07:56 +00005503 ConstantExpr::getShl(ConstantInt::getAllOnesValue(AndTy),
5504 OShAmt);
Chris Lattnere1b4d2a2004-09-23 21:52:49 +00005505 if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())
5506 CanFold = true;
5507 }
Misha Brukmanb1c93172005-04-21 23:48:37 +00005508
Chris Lattnere1b4d2a2004-09-23 21:52:49 +00005509 if (CanFold) {
Chris Lattner6afc02f2004-09-28 17:54:07 +00005510 Constant *NewCst;
5511 if (Shift->getOpcode() == Instruction::Shl)
Reid Spencerfdff9382006-11-08 06:47:33 +00005512 NewCst = ConstantExpr::getLShr(CI, ShAmt);
Chris Lattner6afc02f2004-09-28 17:54:07 +00005513 else
5514 NewCst = ConstantExpr::getShl(CI, ShAmt);
Chris Lattnerbfff18a2004-09-27 19:29:18 +00005515
Chris Lattnere1b4d2a2004-09-23 21:52:49 +00005516 // Check to see if we are shifting out any of the bits being
5517 // compared.
5518 if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){
5519 // If we shifted bits out, the fold is not going to work out.
5520 // As a special case, check to see if this means that the
5521 // result is always true or false now.
Reid Spencer266e42b2006-12-23 06:05:41 +00005522 if (I.getPredicate() == ICmpInst::ICMP_EQ)
Zhou Sheng75b871f2007-01-11 12:24:14 +00005523 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
Reid Spencer266e42b2006-12-23 06:05:41 +00005524 if (I.getPredicate() == ICmpInst::ICMP_NE)
Zhou Sheng75b871f2007-01-11 12:24:14 +00005525 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
Chris Lattnere1b4d2a2004-09-23 21:52:49 +00005526 } else {
5527 I.setOperand(1, NewCst);
Chris Lattner6afc02f2004-09-28 17:54:07 +00005528 Constant *NewAndCST;
5529 if (Shift->getOpcode() == Instruction::Shl)
Reid Spencerfdff9382006-11-08 06:47:33 +00005530 NewAndCST = ConstantExpr::getLShr(AndCST, ShAmt);
Chris Lattner6afc02f2004-09-28 17:54:07 +00005531 else
5532 NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
5533 LHSI->setOperand(1, NewAndCST);
Reid Spencer6ff3e732007-01-04 05:23:51 +00005534 LHSI->setOperand(0, Shift->getOperand(0));
Chris Lattnerb15e2b12007-03-02 21:28:56 +00005535 AddToWorkList(Shift); // Shift is dead.
Chris Lattnere1b4d2a2004-09-23 21:52:49 +00005536 AddUsesToWorkList(I);
5537 return &I;
Chris Lattner1638de42004-07-21 19:50:44 +00005538 }
5539 }
Chris Lattner35167c32004-06-09 07:59:58 +00005540 }
Chris Lattnerb3f24c92006-09-18 04:22:48 +00005541
5542 // Turn ((X >> Y) & C) == 0 into (X & (C << Y)) == 0. The later is
5543 // preferable because it allows the C<<Y expression to be hoisted out
5544 // of a loop if Y is invariant and X is not.
5545 if (Shift && Shift->hasOneUse() && CI->isNullValue() &&
Chris Lattnerde077922006-09-18 18:27:05 +00005546 I.isEquality() && !Shift->isArithmeticShift() &&
5547 isa<Instruction>(Shift->getOperand(0))) {
Chris Lattnerb3f24c92006-09-18 04:22:48 +00005548 // Compute C << Y.
5549 Value *NS;
Reid Spencerfdff9382006-11-08 06:47:33 +00005550 if (Shift->getOpcode() == Instruction::LShr) {
Reid Spencer0d5f9232007-02-02 14:08:20 +00005551 NS = BinaryOperator::createShl(AndCST,
Reid Spencer2341c222007-02-02 02:16:23 +00005552 Shift->getOperand(1), "tmp");
Chris Lattnerb3f24c92006-09-18 04:22:48 +00005553 } else {
Reid Spencer2a499b02006-12-13 17:19:09 +00005554 // Insert a logical shift.
Reid Spencer0d5f9232007-02-02 14:08:20 +00005555 NS = BinaryOperator::createLShr(AndCST,
Reid Spencer2341c222007-02-02 02:16:23 +00005556 Shift->getOperand(1), "tmp");
Chris Lattnerb3f24c92006-09-18 04:22:48 +00005557 }
5558 InsertNewInstBefore(cast<Instruction>(NS), I);
5559
Chris Lattnerb3f24c92006-09-18 04:22:48 +00005560 // Compute X & (C << Y).
Reid Spencer6ff3e732007-01-04 05:23:51 +00005561 Instruction *NewAnd = BinaryOperator::createAnd(
5562 Shift->getOperand(0), NS, LHSI->getName());
Chris Lattnerb3f24c92006-09-18 04:22:48 +00005563 InsertNewInstBefore(NewAnd, I);
5564
5565 I.setOperand(0, NewAnd);
5566 return &I;
5567 }
Chris Lattnere1b4d2a2004-09-23 21:52:49 +00005568 }
5569 break;
Chris Lattnerbfff18a2004-09-27 19:29:18 +00005570
Reid Spencer266e42b2006-12-23 06:05:41 +00005571 case Instruction::Shl: // (icmp pred (shl X, ShAmt), CI)
Reid Spencere0fc4df2006-10-20 07:07:24 +00005572 if (ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
Chris Lattnerb3f24c92006-09-18 04:22:48 +00005573 if (I.isEquality()) {
Chris Lattner19b57f52005-06-15 20:53:31 +00005574 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
5575
5576 // Check that the shift amount is in range. If not, don't perform
5577 // undefined shifts. When the shift is visited it will be
5578 // simplified.
Reid Spencere0fc4df2006-10-20 07:07:24 +00005579 if (ShAmt->getZExtValue() >= TypeBits)
Chris Lattner19b57f52005-06-15 20:53:31 +00005580 break;
5581
Chris Lattner272d5ca2004-09-28 18:22:15 +00005582 // If we are comparing against bits always shifted out, the
5583 // comparison cannot succeed.
Misha Brukmanb1c93172005-04-21 23:48:37 +00005584 Constant *Comp =
Reid Spencerfdff9382006-11-08 06:47:33 +00005585 ConstantExpr::getShl(ConstantExpr::getLShr(CI, ShAmt), ShAmt);
Chris Lattner272d5ca2004-09-28 18:22:15 +00005586 if (Comp != CI) {// Comparing against a bit that we know is zero.
Reid Spencer266e42b2006-12-23 06:05:41 +00005587 bool IsICMP_NE = I.getPredicate() == ICmpInst::ICMP_NE;
Reid Spencercddc9df2007-01-12 04:24:46 +00005588 Constant *Cst = ConstantInt::get(Type::Int1Ty, IsICMP_NE);
Chris Lattner272d5ca2004-09-28 18:22:15 +00005589 return ReplaceInstUsesWith(I, Cst);
5590 }
5591
5592 if (LHSI->hasOneUse()) {
5593 // Otherwise strength reduce the shift into an and.
Reid Spencere0fc4df2006-10-20 07:07:24 +00005594 unsigned ShAmtVal = (unsigned)ShAmt->getZExtValue();
Chris Lattner272d5ca2004-09-28 18:22:15 +00005595 uint64_t Val = (1ULL << (TypeBits-ShAmtVal))-1;
Reid Spencerc635f472006-12-31 05:48:39 +00005596 Constant *Mask = ConstantInt::get(CI->getType(), Val);
Misha Brukmanb1c93172005-04-21 23:48:37 +00005597
Chris Lattner272d5ca2004-09-28 18:22:15 +00005598 Instruction *AndI =
5599 BinaryOperator::createAnd(LHSI->getOperand(0),
5600 Mask, LHSI->getName()+".mask");
5601 Value *And = InsertNewInstBefore(AndI, I);
Reid Spencer266e42b2006-12-23 06:05:41 +00005602 return new ICmpInst(I.getPredicate(), And,
Reid Spencerfdff9382006-11-08 06:47:33 +00005603 ConstantExpr::getLShr(CI, ShAmt));
Chris Lattner272d5ca2004-09-28 18:22:15 +00005604 }
5605 }
Chris Lattner272d5ca2004-09-28 18:22:15 +00005606 }
5607 break;
5608
Reid Spencer266e42b2006-12-23 06:05:41 +00005609 case Instruction::LShr: // (icmp pred (shr X, ShAmt), CI)
Reid Spencerfdff9382006-11-08 06:47:33 +00005610 case Instruction::AShr:
Reid Spencere0fc4df2006-10-20 07:07:24 +00005611 if (ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
Chris Lattnerb3f24c92006-09-18 04:22:48 +00005612 if (I.isEquality()) {
Chris Lattner19b57f52005-06-15 20:53:31 +00005613 // Check that the shift amount is in range. If not, don't perform
5614 // undefined shifts. When the shift is visited it will be
5615 // simplified.
Chris Lattner104002b2005-06-16 01:52:07 +00005616 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
Reid Spencere0fc4df2006-10-20 07:07:24 +00005617 if (ShAmt->getZExtValue() >= TypeBits)
Chris Lattner19b57f52005-06-15 20:53:31 +00005618 break;
5619
Chris Lattner1023b872004-09-27 16:18:50 +00005620 // If we are comparing against bits always shifted out, the
5621 // comparison cannot succeed.
Reid Spencerfdff9382006-11-08 06:47:33 +00005622 Constant *Comp;
Reid Spencerc635f472006-12-31 05:48:39 +00005623 if (LHSI->getOpcode() == Instruction::LShr)
Reid Spencerfdff9382006-11-08 06:47:33 +00005624 Comp = ConstantExpr::getLShr(ConstantExpr::getShl(CI, ShAmt),
5625 ShAmt);
5626 else
5627 Comp = ConstantExpr::getAShr(ConstantExpr::getShl(CI, ShAmt),
5628 ShAmt);
Misha Brukmanb1c93172005-04-21 23:48:37 +00005629
Chris Lattner1023b872004-09-27 16:18:50 +00005630 if (Comp != CI) {// Comparing against a bit that we know is zero.
Reid Spencer266e42b2006-12-23 06:05:41 +00005631 bool IsICMP_NE = I.getPredicate() == ICmpInst::ICMP_NE;
Reid Spencercddc9df2007-01-12 04:24:46 +00005632 Constant *Cst = ConstantInt::get(Type::Int1Ty, IsICMP_NE);
Chris Lattner1023b872004-09-27 16:18:50 +00005633 return ReplaceInstUsesWith(I, Cst);
5634 }
Misha Brukmanb1c93172005-04-21 23:48:37 +00005635
Chris Lattner1023b872004-09-27 16:18:50 +00005636 if (LHSI->hasOneUse() || CI->isNullValue()) {
Reid Spencere0fc4df2006-10-20 07:07:24 +00005637 unsigned ShAmtVal = (unsigned)ShAmt->getZExtValue();
Chris Lattner272d5ca2004-09-28 18:22:15 +00005638
Chris Lattner1023b872004-09-27 16:18:50 +00005639 // Otherwise strength reduce the shift into an and.
5640 uint64_t Val = ~0ULL; // All ones.
5641 Val <<= ShAmtVal; // Shift over to the right spot.
Reid Spencerc635f472006-12-31 05:48:39 +00005642 Val &= ~0ULL >> (64-TypeBits);
5643 Constant *Mask = ConstantInt::get(CI->getType(), Val);
Misha Brukmanb1c93172005-04-21 23:48:37 +00005644
Chris Lattner1023b872004-09-27 16:18:50 +00005645 Instruction *AndI =
5646 BinaryOperator::createAnd(LHSI->getOperand(0),
5647 Mask, LHSI->getName()+".mask");
5648 Value *And = InsertNewInstBefore(AndI, I);
Reid Spencer266e42b2006-12-23 06:05:41 +00005649 return new ICmpInst(I.getPredicate(), And,
Chris Lattner1023b872004-09-27 16:18:50 +00005650 ConstantExpr::getShl(CI, ShAmt));
5651 }
Chris Lattner1023b872004-09-27 16:18:50 +00005652 }
5653 }
5654 break;
Chris Lattner7e794272004-09-24 15:21:34 +00005655
Reid Spencer7e80b0b2006-10-26 06:15:43 +00005656 case Instruction::SDiv:
5657 case Instruction::UDiv:
Reid Spencer266e42b2006-12-23 06:05:41 +00005658 // Fold: icmp pred ([us]div X, C1), C2 -> range test
Reid Spencer7e80b0b2006-10-26 06:15:43 +00005659 // Fold this div into the comparison, producing a range check.
5660 // Determine, based on the divide type, what the range is being
5661 // checked. If there is an overflow on the low or high side, remember
5662 // it, otherwise compute the range [low, hi) bounding the new value.
5663 // See: InsertRangeTest above for the kinds of replacements possible.
Chris Lattner6862fbd2004-09-29 17:40:11 +00005664 if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
Reid Spencer7e80b0b2006-10-26 06:15:43 +00005665 // FIXME: If the operand types don't match the type of the divide
5666 // then don't attempt this transform. The code below doesn't have the
5667 // logic to deal with a signed divide and an unsigned compare (and
5668 // vice versa). This is because (x /s C1) <s C2 produces different
5669 // results than (x /s C1) <u C2 or (x /u C1) <s C2 or even
5670 // (x /u C1) <u C2. Simply casting the operands and result won't
5671 // work. :( The if statement below tests that condition and bails
5672 // if it finds it.
Reid Spencer266e42b2006-12-23 06:05:41 +00005673 bool DivIsSigned = LHSI->getOpcode() == Instruction::SDiv;
5674 if (!I.isEquality() && DivIsSigned != I.isSignedPredicate())
Reid Spencer7e80b0b2006-10-26 06:15:43 +00005675 break;
5676
5677 // Initialize the variables that will indicate the nature of the
5678 // range check.
5679 bool LoOverflow = false, HiOverflow = false;
Chris Lattner6862fbd2004-09-29 17:40:11 +00005680 ConstantInt *LoBound = 0, *HiBound = 0;
5681
Reid Spencer7e80b0b2006-10-26 06:15:43 +00005682 // Compute Prod = CI * DivRHS. We are essentially solving an equation
5683 // of form X/C1=C2. We solve for X by multiplying C1 (DivRHS) and
5684 // C2 (CI). By solving for X we can turn this into a range check
5685 // instead of computing a divide.
5686 ConstantInt *Prod =
5687 cast<ConstantInt>(ConstantExpr::getMul(CI, DivRHS));
Chris Lattner6862fbd2004-09-29 17:40:11 +00005688
Reid Spencer7e80b0b2006-10-26 06:15:43 +00005689 // Determine if the product overflows by seeing if the product is
5690 // not equal to the divide. Make sure we do the same kind of divide
5691 // as in the LHS instruction that we're folding.
5692 bool ProdOV = !DivRHS->isNullValue() &&
Reid Spencer266e42b2006-12-23 06:05:41 +00005693 (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS) :
Reid Spencer7e80b0b2006-10-26 06:15:43 +00005694 ConstantExpr::getUDiv(Prod, DivRHS)) != CI;
5695
Reid Spencer266e42b2006-12-23 06:05:41 +00005696 // Get the ICmp opcode
5697 ICmpInst::Predicate predicate = I.getPredicate();
Chris Lattnera92af962004-10-11 19:40:04 +00005698
Reid Spencer7e80b0b2006-10-26 06:15:43 +00005699 if (DivRHS->isNullValue()) {
5700 // Don't hack on divide by zeros!
Reid Spencer266e42b2006-12-23 06:05:41 +00005701 } else if (!DivIsSigned) { // udiv
Chris Lattner6862fbd2004-09-29 17:40:11 +00005702 LoBound = Prod;
5703 LoOverflow = ProdOV;
5704 HiOverflow = ProdOV || AddWithOverflow(HiBound, LoBound, DivRHS);
Reid Spencer450434e2007-03-19 20:58:18 +00005705 } else if (DivRHS->getValue().isPositive()) { // Divisor is > 0.
Chris Lattner6862fbd2004-09-29 17:40:11 +00005706 if (CI->isNullValue()) { // (X / pos) op 0
5707 // Can't overflow.
5708 LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
5709 HiBound = DivRHS;
Reid Spencer450434e2007-03-19 20:58:18 +00005710 } else if (CI->getValue().isPositive()) { // (X / pos) op pos
Chris Lattner6862fbd2004-09-29 17:40:11 +00005711 LoBound = Prod;
5712 LoOverflow = ProdOV;
5713 HiOverflow = ProdOV || AddWithOverflow(HiBound, Prod, DivRHS);
5714 } else { // (X / pos) op neg
5715 Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS));
5716 LoOverflow = AddWithOverflow(LoBound, Prod,
5717 cast<ConstantInt>(DivRHSH));
5718 HiBound = Prod;
5719 HiOverflow = ProdOV;
5720 }
Reid Spencer7e80b0b2006-10-26 06:15:43 +00005721 } else { // Divisor is < 0.
Chris Lattner6862fbd2004-09-29 17:40:11 +00005722 if (CI->isNullValue()) { // (X / neg) op 0
5723 LoBound = AddOne(DivRHS);
5724 HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
Chris Lattner73bcba52005-06-17 02:05:55 +00005725 if (HiBound == DivRHS)
Reid Spencer7e80b0b2006-10-26 06:15:43 +00005726 LoBound = 0; // - INTMIN = INTMIN
Reid Spencer450434e2007-03-19 20:58:18 +00005727 } else if (CI->getValue().isPositive()) { // (X / neg) op pos
Chris Lattner6862fbd2004-09-29 17:40:11 +00005728 HiOverflow = LoOverflow = ProdOV;
5729 if (!LoOverflow)
5730 LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS));
5731 HiBound = AddOne(Prod);
5732 } else { // (X / neg) op neg
5733 LoBound = Prod;
5734 LoOverflow = HiOverflow = ProdOV;
5735 HiBound = cast<ConstantInt>(ConstantExpr::getSub(Prod, DivRHS));
5736 }
Chris Lattner0b41e862004-10-08 19:15:44 +00005737
Chris Lattnera92af962004-10-11 19:40:04 +00005738 // Dividing by a negate swaps the condition.
Reid Spencer266e42b2006-12-23 06:05:41 +00005739 predicate = ICmpInst::getSwappedPredicate(predicate);
Chris Lattner6862fbd2004-09-29 17:40:11 +00005740 }
5741
5742 if (LoBound) {
5743 Value *X = LHSI->getOperand(0);
Reid Spencer266e42b2006-12-23 06:05:41 +00005744 switch (predicate) {
5745 default: assert(0 && "Unhandled icmp opcode!");
5746 case ICmpInst::ICMP_EQ:
Chris Lattner6862fbd2004-09-29 17:40:11 +00005747 if (LoOverflow && HiOverflow)
Zhou Sheng75b871f2007-01-11 12:24:14 +00005748 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
Chris Lattner6862fbd2004-09-29 17:40:11 +00005749 else if (HiOverflow)
Reid Spencer266e42b2006-12-23 06:05:41 +00005750 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
5751 ICmpInst::ICMP_UGE, X, LoBound);
Chris Lattner6862fbd2004-09-29 17:40:11 +00005752 else if (LoOverflow)
Reid Spencer266e42b2006-12-23 06:05:41 +00005753 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
5754 ICmpInst::ICMP_ULT, X, HiBound);
Chris Lattner6862fbd2004-09-29 17:40:11 +00005755 else
Reid Spencer266e42b2006-12-23 06:05:41 +00005756 return InsertRangeTest(X, LoBound, HiBound, DivIsSigned,
5757 true, I);
5758 case ICmpInst::ICMP_NE:
Chris Lattner6862fbd2004-09-29 17:40:11 +00005759 if (LoOverflow && HiOverflow)
Zhou Sheng75b871f2007-01-11 12:24:14 +00005760 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
Chris Lattner6862fbd2004-09-29 17:40:11 +00005761 else if (HiOverflow)
Reid Spencer266e42b2006-12-23 06:05:41 +00005762 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
5763 ICmpInst::ICMP_ULT, X, LoBound);
Chris Lattner6862fbd2004-09-29 17:40:11 +00005764 else if (LoOverflow)
Reid Spencer266e42b2006-12-23 06:05:41 +00005765 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
5766 ICmpInst::ICMP_UGE, X, HiBound);
Chris Lattner6862fbd2004-09-29 17:40:11 +00005767 else
Reid Spencer266e42b2006-12-23 06:05:41 +00005768 return InsertRangeTest(X, LoBound, HiBound, DivIsSigned,
5769 false, I);
5770 case ICmpInst::ICMP_ULT:
5771 case ICmpInst::ICMP_SLT:
Chris Lattner6862fbd2004-09-29 17:40:11 +00005772 if (LoOverflow)
Zhou Sheng75b871f2007-01-11 12:24:14 +00005773 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
Reid Spencer266e42b2006-12-23 06:05:41 +00005774 return new ICmpInst(predicate, X, LoBound);
5775 case ICmpInst::ICMP_UGT:
5776 case ICmpInst::ICMP_SGT:
Chris Lattner6862fbd2004-09-29 17:40:11 +00005777 if (HiOverflow)
Zhou Sheng75b871f2007-01-11 12:24:14 +00005778 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
Reid Spencer266e42b2006-12-23 06:05:41 +00005779 if (predicate == ICmpInst::ICMP_UGT)
5780 return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound);
5781 else
5782 return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound);
Chris Lattner6862fbd2004-09-29 17:40:11 +00005783 }
5784 }
5785 }
5786 break;
Chris Lattnere1b4d2a2004-09-23 21:52:49 +00005787 }
Misha Brukmanb1c93172005-04-21 23:48:37 +00005788
Reid Spencer266e42b2006-12-23 06:05:41 +00005789 // Simplify icmp_eq and icmp_ne instructions with integer constant RHS.
Chris Lattnerb3f24c92006-09-18 04:22:48 +00005790 if (I.isEquality()) {
Reid Spencer266e42b2006-12-23 06:05:41 +00005791 bool isICMP_NE = I.getPredicate() == ICmpInst::ICMP_NE;
Chris Lattnerd492a0b2003-07-23 17:02:11 +00005792
Reid Spencere0fc4df2006-10-20 07:07:24 +00005793 // If the first operand is (add|sub|and|or|xor|rem) with a constant, and
5794 // the second operand is a constant, simplify a bit.
Chris Lattnerc992add2003-08-13 05:33:12 +00005795 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) {
5796 switch (BO->getOpcode()) {
Reid Spencere0fc4df2006-10-20 07:07:24 +00005797 case Instruction::SRem:
5798 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
5799 if (CI->isNullValue() && isa<ConstantInt>(BO->getOperand(1)) &&
5800 BO->hasOneUse()) {
5801 int64_t V = cast<ConstantInt>(BO->getOperand(1))->getSExtValue();
5802 if (V > 1 && isPowerOf2_64(V)) {
Reid Spencer7eb55b32006-11-02 01:53:59 +00005803 Value *NewRem = InsertNewInstBefore(BinaryOperator::createURem(
5804 BO->getOperand(0), BO->getOperand(1), BO->getName()), I);
Reid Spencer266e42b2006-12-23 06:05:41 +00005805 return new ICmpInst(I.getPredicate(), NewRem,
5806 Constant::getNullValue(BO->getType()));
Chris Lattner23b47b62004-07-06 07:38:18 +00005807 }
Chris Lattner22d00a82005-08-02 19:16:58 +00005808 }
Misha Brukmanb1c93172005-04-21 23:48:37 +00005809 break;
Chris Lattnerc992add2003-08-13 05:33:12 +00005810 case Instruction::Add:
Chris Lattner6e079362004-06-27 22:51:36 +00005811 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
5812 if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
Chris Lattnerb121ae12004-09-21 21:35:23 +00005813 if (BO->hasOneUse())
Reid Spencer266e42b2006-12-23 06:05:41 +00005814 return new ICmpInst(I.getPredicate(), BO->getOperand(0),
5815 ConstantExpr::getSub(CI, BOp1C));
Chris Lattner6e079362004-06-27 22:51:36 +00005816 } else if (CI->isNullValue()) {
Chris Lattnerc992add2003-08-13 05:33:12 +00005817 // Replace ((add A, B) != 0) with (A != -B) if A or B is
5818 // efficiently invertible, or if the add has just this one use.
5819 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
Misha Brukmanb1c93172005-04-21 23:48:37 +00005820
Chris Lattnerc992add2003-08-13 05:33:12 +00005821 if (Value *NegVal = dyn_castNegVal(BOp1))
Reid Spencer266e42b2006-12-23 06:05:41 +00005822 return new ICmpInst(I.getPredicate(), BOp0, NegVal);
Chris Lattnerc992add2003-08-13 05:33:12 +00005823 else if (Value *NegVal = dyn_castNegVal(BOp0))
Reid Spencer266e42b2006-12-23 06:05:41 +00005824 return new ICmpInst(I.getPredicate(), NegVal, BOp1);
Chris Lattnerf95d9b92003-10-15 16:48:29 +00005825 else if (BO->hasOneUse()) {
Chris Lattner6e0123b2007-02-11 01:23:03 +00005826 Instruction *Neg = BinaryOperator::createNeg(BOp1);
Chris Lattnerc992add2003-08-13 05:33:12 +00005827 InsertNewInstBefore(Neg, I);
Chris Lattner6e0123b2007-02-11 01:23:03 +00005828 Neg->takeName(BO);
Reid Spencer266e42b2006-12-23 06:05:41 +00005829 return new ICmpInst(I.getPredicate(), BOp0, Neg);
Chris Lattnerc992add2003-08-13 05:33:12 +00005830 }
5831 }
5832 break;
5833 case Instruction::Xor:
5834 // For the xor case, we can xor two constants together, eliminating
5835 // the explicit xor.
5836 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
Reid Spencer266e42b2006-12-23 06:05:41 +00005837 return new ICmpInst(I.getPredicate(), BO->getOperand(0),
5838 ConstantExpr::getXor(CI, BOC));
Chris Lattnerc992add2003-08-13 05:33:12 +00005839
5840 // FALLTHROUGH
5841 case Instruction::Sub:
5842 // Replace (([sub|xor] A, B) != 0) with (A != B)
5843 if (CI->isNullValue())
Reid Spencer266e42b2006-12-23 06:05:41 +00005844 return new ICmpInst(I.getPredicate(), BO->getOperand(0),
5845 BO->getOperand(1));
Chris Lattnerc992add2003-08-13 05:33:12 +00005846 break;
5847
5848 case Instruction::Or:
5849 // If bits are being or'd in that are not present in the constant we
5850 // are comparing against, then the comparison could never succeed!
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00005851 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
Chris Lattnerc8e7e292004-06-10 02:12:35 +00005852 Constant *NotCI = ConstantExpr::getNot(CI);
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00005853 if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
Reid Spencercddc9df2007-01-12 04:24:46 +00005854 return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
5855 isICMP_NE));
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00005856 }
Chris Lattnerc992add2003-08-13 05:33:12 +00005857 break;
5858
5859 case Instruction::And:
5860 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
Chris Lattnerd492a0b2003-07-23 17:02:11 +00005861 // If bits are being compared against that are and'd out, then the
5862 // comparison can never succeed!
Chris Lattnerc8e7e292004-06-10 02:12:35 +00005863 if (!ConstantExpr::getAnd(CI,
5864 ConstantExpr::getNot(BOC))->isNullValue())
Reid Spencercddc9df2007-01-12 04:24:46 +00005865 return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
5866 isICMP_NE));
Chris Lattnerc992add2003-08-13 05:33:12 +00005867
Chris Lattner35167c32004-06-09 07:59:58 +00005868 // If we have ((X & C) == C), turn it into ((X & C) != 0).
Chris Lattneree59d4b2004-06-10 02:33:20 +00005869 if (CI == BOC && isOneBitSet(CI))
Reid Spencer266e42b2006-12-23 06:05:41 +00005870 return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ :
5871 ICmpInst::ICMP_NE, Op0,
5872 Constant::getNullValue(CI->getType()));
Chris Lattner35167c32004-06-09 07:59:58 +00005873
Reid Spencer266e42b2006-12-23 06:05:41 +00005874 // Replace (and X, (1 << size(X)-1) != 0) with x s< 0
Chris Lattnerc992add2003-08-13 05:33:12 +00005875 if (isSignBit(BOC)) {
5876 Value *X = BO->getOperand(0);
Reid Spencer266e42b2006-12-23 06:05:41 +00005877 Constant *Zero = Constant::getNullValue(X->getType());
5878 ICmpInst::Predicate pred = isICMP_NE ?
5879 ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
5880 return new ICmpInst(pred, X, Zero);
Chris Lattnerc992add2003-08-13 05:33:12 +00005881 }
Misha Brukmanb1c93172005-04-21 23:48:37 +00005882
Chris Lattnerbfff18a2004-09-27 19:29:18 +00005883 // ((X & ~7) == 0) --> X < 8
Chris Lattner8fc5af42004-09-23 21:46:38 +00005884 if (CI->isNullValue() && isHighOnes(BOC)) {
5885 Value *X = BO->getOperand(0);
Chris Lattnerbfff18a2004-09-27 19:29:18 +00005886 Constant *NegX = ConstantExpr::getNeg(BOC);
Reid Spencer266e42b2006-12-23 06:05:41 +00005887 ICmpInst::Predicate pred = isICMP_NE ?
5888 ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
5889 return new ICmpInst(pred, X, NegX);
Chris Lattner8fc5af42004-09-23 21:46:38 +00005890 }
5891
Chris Lattnerd492a0b2003-07-23 17:02:11 +00005892 }
Chris Lattnerc992add2003-08-13 05:33:12 +00005893 default: break;
5894 }
Chris Lattnera7942b72006-11-29 05:02:16 +00005895 } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Op0)) {
5896 // Handle set{eq|ne} <intrinsic>, intcst.
5897 switch (II->getIntrinsicID()) {
5898 default: break;
Reid Spencer266e42b2006-12-23 06:05:41 +00005899 case Intrinsic::bswap_i16:
5900 // icmp eq (bswap(x)), c -> icmp eq (x,bswap(c))
Chris Lattnerb15e2b12007-03-02 21:28:56 +00005901 AddToWorkList(II); // Dead?
Chris Lattnera7942b72006-11-29 05:02:16 +00005902 I.setOperand(0, II->getOperand(1));
Reid Spencerc635f472006-12-31 05:48:39 +00005903 I.setOperand(1, ConstantInt::get(Type::Int16Ty,
Chris Lattnera7942b72006-11-29 05:02:16 +00005904 ByteSwap_16(CI->getZExtValue())));
5905 return &I;
Reid Spencer266e42b2006-12-23 06:05:41 +00005906 case Intrinsic::bswap_i32:
5907 // icmp eq (bswap(x)), c -> icmp eq (x,bswap(c))
Chris Lattnerb15e2b12007-03-02 21:28:56 +00005908 AddToWorkList(II); // Dead?
Chris Lattnera7942b72006-11-29 05:02:16 +00005909 I.setOperand(0, II->getOperand(1));
Reid Spencerc635f472006-12-31 05:48:39 +00005910 I.setOperand(1, ConstantInt::get(Type::Int32Ty,
Chris Lattnera7942b72006-11-29 05:02:16 +00005911 ByteSwap_32(CI->getZExtValue())));
5912 return &I;
Reid Spencer266e42b2006-12-23 06:05:41 +00005913 case Intrinsic::bswap_i64:
5914 // icmp eq (bswap(x)), c -> icmp eq (x,bswap(c))
Chris Lattnerb15e2b12007-03-02 21:28:56 +00005915 AddToWorkList(II); // Dead?
Chris Lattnera7942b72006-11-29 05:02:16 +00005916 I.setOperand(0, II->getOperand(1));
Reid Spencerc635f472006-12-31 05:48:39 +00005917 I.setOperand(1, ConstantInt::get(Type::Int64Ty,
Chris Lattnera7942b72006-11-29 05:02:16 +00005918 ByteSwap_64(CI->getZExtValue())));
5919 return &I;
5920 }
Chris Lattnerc992add2003-08-13 05:33:12 +00005921 }
Reid Spencer266e42b2006-12-23 06:05:41 +00005922 } else { // Not a ICMP_EQ/ICMP_NE
5923 // If the LHS is a cast from an integral value of the same size, then
5924 // since we know the RHS is a constant, try to simlify.
Chris Lattner2b55ea32004-02-23 07:16:20 +00005925 if (CastInst *Cast = dyn_cast<CastInst>(Op0)) {
5926 Value *CastOp = Cast->getOperand(0);
5927 const Type *SrcTy = CastOp->getType();
Chris Lattnerd1f46d32005-04-24 06:59:08 +00005928 unsigned SrcTySize = SrcTy->getPrimitiveSizeInBits();
Chris Lattner03c49532007-01-15 02:27:26 +00005929 if (SrcTy->isInteger() &&
Chris Lattnerd1f46d32005-04-24 06:59:08 +00005930 SrcTySize == Cast->getType()->getPrimitiveSizeInBits()) {
Reid Spencer266e42b2006-12-23 06:05:41 +00005931 // If this is an unsigned comparison, try to make the comparison use
5932 // smaller constant values.
5933 switch (I.getPredicate()) {
5934 default: break;
5935 case ICmpInst::ICMP_ULT: { // X u< 128 => X s> -1
5936 ConstantInt *CUI = cast<ConstantInt>(CI);
5937 if (CUI->getZExtValue() == 1ULL << (SrcTySize-1))
5938 return new ICmpInst(ICmpInst::ICMP_SGT, CastOp,
Reid Spencer24f1a0e2007-03-01 19:33:52 +00005939 ConstantInt::get(SrcTy, -1ULL));
Reid Spencer266e42b2006-12-23 06:05:41 +00005940 break;
5941 }
5942 case ICmpInst::ICMP_UGT: { // X u> 127 => X s< 0
5943 ConstantInt *CUI = cast<ConstantInt>(CI);
5944 if (CUI->getZExtValue() == (1ULL << (SrcTySize-1))-1)
5945 return new ICmpInst(ICmpInst::ICMP_SLT, CastOp,
5946 Constant::getNullValue(SrcTy));
5947 break;
5948 }
Chris Lattner2b55ea32004-02-23 07:16:20 +00005949 }
Reid Spencer266e42b2006-12-23 06:05:41 +00005950
Chris Lattner2b55ea32004-02-23 07:16:20 +00005951 }
5952 }
Chris Lattnere967b342003-06-04 05:10:11 +00005953 }
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00005954 }
5955
Reid Spencer266e42b2006-12-23 06:05:41 +00005956 // Handle icmp with constant RHS
Chris Lattner77c32c32005-04-23 15:31:55 +00005957 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
5958 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
5959 switch (LHSI->getOpcode()) {
Chris Lattnera816eee2005-05-01 04:42:15 +00005960 case Instruction::GetElementPtr:
5961 if (RHSC->isNullValue()) {
Reid Spencer266e42b2006-12-23 06:05:41 +00005962 // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null
Chris Lattnera816eee2005-05-01 04:42:15 +00005963 bool isAllZeros = true;
5964 for (unsigned i = 1, e = LHSI->getNumOperands(); i != e; ++i)
5965 if (!isa<Constant>(LHSI->getOperand(i)) ||
5966 !cast<Constant>(LHSI->getOperand(i))->isNullValue()) {
5967 isAllZeros = false;
5968 break;
5969 }
5970 if (isAllZeros)
Reid Spencer266e42b2006-12-23 06:05:41 +00005971 return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
Chris Lattnera816eee2005-05-01 04:42:15 +00005972 Constant::getNullValue(LHSI->getOperand(0)->getType()));
5973 }
5974 break;
5975
Chris Lattner77c32c32005-04-23 15:31:55 +00005976 case Instruction::PHI:
5977 if (Instruction *NV = FoldOpIntoPhi(I))
5978 return NV;
5979 break;
5980 case Instruction::Select:
5981 // If either operand of the select is a constant, we can fold the
5982 // comparison into the select arms, which will cause one to be
5983 // constant folded and the select turned into a bitwise or.
5984 Value *Op1 = 0, *Op2 = 0;
5985 if (LHSI->hasOneUse()) {
5986 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
5987 // Fold the known value into the constant operand.
Reid Spencer266e42b2006-12-23 06:05:41 +00005988 Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
5989 // Insert a new ICmp of the other select operand.
5990 Op2 = InsertNewInstBefore(new ICmpInst(I.getPredicate(),
5991 LHSI->getOperand(2), RHSC,
5992 I.getName()), I);
Chris Lattner77c32c32005-04-23 15:31:55 +00005993 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
5994 // Fold the known value into the constant operand.
Reid Spencer266e42b2006-12-23 06:05:41 +00005995 Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
5996 // Insert a new ICmp of the other select operand.
5997 Op1 = InsertNewInstBefore(new ICmpInst(I.getPredicate(),
5998 LHSI->getOperand(1), RHSC,
5999 I.getName()), I);
Chris Lattner77c32c32005-04-23 15:31:55 +00006000 }
6001 }
Jeff Cohen82639852005-04-23 21:38:35 +00006002
Chris Lattner77c32c32005-04-23 15:31:55 +00006003 if (Op1)
6004 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
6005 break;
6006 }
6007 }
6008
Reid Spencer266e42b2006-12-23 06:05:41 +00006009 // If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now.
Chris Lattner0798af32005-01-13 20:14:25 +00006010 if (User *GEP = dyn_castGetElementPtr(Op0))
Reid Spencer266e42b2006-12-23 06:05:41 +00006011 if (Instruction *NI = FoldGEPICmp(GEP, Op1, I.getPredicate(), I))
Chris Lattner0798af32005-01-13 20:14:25 +00006012 return NI;
6013 if (User *GEP = dyn_castGetElementPtr(Op1))
Reid Spencer266e42b2006-12-23 06:05:41 +00006014 if (Instruction *NI = FoldGEPICmp(GEP, Op0,
6015 ICmpInst::getSwappedPredicate(I.getPredicate()), I))
Chris Lattner0798af32005-01-13 20:14:25 +00006016 return NI;
6017
Reid Spencer266e42b2006-12-23 06:05:41 +00006018 // Test to see if the operands of the icmp are casted versions of other
Chris Lattner64d87b02007-01-06 01:45:59 +00006019 // values. If the ptr->ptr cast can be stripped off both arguments, we do so
6020 // now.
6021 if (BitCastInst *CI = dyn_cast<BitCastInst>(Op0)) {
6022 if (isa<PointerType>(Op0->getType()) &&
6023 (isa<Constant>(Op1) || isa<BitCastInst>(Op1))) {
Chris Lattner16930792003-11-03 04:25:02 +00006024 // We keep moving the cast from the left operand over to the right
6025 // operand, where it can often be eliminated completely.
Chris Lattner64d87b02007-01-06 01:45:59 +00006026 Op0 = CI->getOperand(0);
Misha Brukmanb1c93172005-04-21 23:48:37 +00006027
Chris Lattner64d87b02007-01-06 01:45:59 +00006028 // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast
6029 // so eliminate it as well.
6030 if (BitCastInst *CI2 = dyn_cast<BitCastInst>(Op1))
6031 Op1 = CI2->getOperand(0);
Misha Brukmanb1c93172005-04-21 23:48:37 +00006032
Chris Lattner16930792003-11-03 04:25:02 +00006033 // If Op1 is a constant, we can fold the cast into the constant.
Chris Lattner64d87b02007-01-06 01:45:59 +00006034 if (Op0->getType() != Op1->getType())
Chris Lattner16930792003-11-03 04:25:02 +00006035 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
Reid Spencerbb65ebf2006-12-12 23:36:14 +00006036 Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType());
Chris Lattner16930792003-11-03 04:25:02 +00006037 } else {
Reid Spencer266e42b2006-12-23 06:05:41 +00006038 // Otherwise, cast the RHS right before the icmp
Reid Spencer13bc5d72006-12-12 09:18:51 +00006039 Op1 = InsertCastBefore(Instruction::BitCast, Op1, Op0->getType(), I);
Chris Lattner16930792003-11-03 04:25:02 +00006040 }
Reid Spencer266e42b2006-12-23 06:05:41 +00006041 return new ICmpInst(I.getPredicate(), Op0, Op1);
Chris Lattner16930792003-11-03 04:25:02 +00006042 }
Chris Lattner64d87b02007-01-06 01:45:59 +00006043 }
6044
6045 if (isa<CastInst>(Op0)) {
Reid Spencer266e42b2006-12-23 06:05:41 +00006046 // Handle the special case of: icmp (cast bool to X), <cst>
Chris Lattner6444c372003-11-03 05:17:03 +00006047 // This comes up when you have code like
6048 // int X = A < B;
6049 // if (X) ...
6050 // For generality, we handle any zero-extension of any operand comparison
Chris Lattnerd1f46d32005-04-24 06:59:08 +00006051 // with a constant or another cast from the same type.
6052 if (isa<ConstantInt>(Op1) || isa<CastInst>(Op1))
Reid Spencer266e42b2006-12-23 06:05:41 +00006053 if (Instruction *R = visitICmpInstWithCastAndCast(I))
Chris Lattnerd1f46d32005-04-24 06:59:08 +00006054 return R;
Chris Lattner6444c372003-11-03 05:17:03 +00006055 }
Chris Lattnerf5c8a0b2006-02-27 01:44:11 +00006056
Chris Lattnerb3f24c92006-09-18 04:22:48 +00006057 if (I.isEquality()) {
Chris Lattner17c7c032007-01-05 03:04:57 +00006058 Value *A, *B, *C, *D;
6059 if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
6060 if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0
6061 Value *OtherVal = A == Op1 ? B : A;
6062 return new ICmpInst(I.getPredicate(), OtherVal,
6063 Constant::getNullValue(A->getType()));
6064 }
6065
6066 if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) {
6067 // A^c1 == C^c2 --> A == C^(c1^c2)
6068 if (ConstantInt *C1 = dyn_cast<ConstantInt>(B))
6069 if (ConstantInt *C2 = dyn_cast<ConstantInt>(D))
6070 if (Op1->hasOneUse()) {
6071 Constant *NC = ConstantExpr::getXor(C1, C2);
6072 Instruction *Xor = BinaryOperator::createXor(C, NC, "tmp");
6073 return new ICmpInst(I.getPredicate(), A,
6074 InsertNewInstBefore(Xor, I));
6075 }
6076
6077 // A^B == A^D -> B == D
6078 if (A == C) return new ICmpInst(I.getPredicate(), B, D);
6079 if (A == D) return new ICmpInst(I.getPredicate(), B, C);
6080 if (B == C) return new ICmpInst(I.getPredicate(), A, D);
6081 if (B == D) return new ICmpInst(I.getPredicate(), A, C);
6082 }
6083 }
6084
6085 if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
6086 (A == Op0 || B == Op0)) {
Chris Lattnerf5c8a0b2006-02-27 01:44:11 +00006087 // A == (A^B) -> B == 0
6088 Value *OtherVal = A == Op0 ? B : A;
Reid Spencer266e42b2006-12-23 06:05:41 +00006089 return new ICmpInst(I.getPredicate(), OtherVal,
6090 Constant::getNullValue(A->getType()));
Chris Lattner17c7c032007-01-05 03:04:57 +00006091 }
6092 if (match(Op0, m_Sub(m_Value(A), m_Value(B))) && A == Op1) {
Chris Lattnerf5c8a0b2006-02-27 01:44:11 +00006093 // (A-B) == A -> B == 0
Reid Spencer266e42b2006-12-23 06:05:41 +00006094 return new ICmpInst(I.getPredicate(), B,
6095 Constant::getNullValue(B->getType()));
Chris Lattner17c7c032007-01-05 03:04:57 +00006096 }
6097 if (match(Op1, m_Sub(m_Value(A), m_Value(B))) && A == Op0) {
Chris Lattnerf5c8a0b2006-02-27 01:44:11 +00006098 // A == (A-B) -> B == 0
Reid Spencer266e42b2006-12-23 06:05:41 +00006099 return new ICmpInst(I.getPredicate(), B,
6100 Constant::getNullValue(B->getType()));
Chris Lattnerf5c8a0b2006-02-27 01:44:11 +00006101 }
Chris Lattnerd12a4bf2006-11-14 06:06:06 +00006102
Chris Lattnerd12a4bf2006-11-14 06:06:06 +00006103 // (X&Z) == (Y&Z) -> (X^Y) & Z == 0
6104 if (Op0->hasOneUse() && Op1->hasOneUse() &&
6105 match(Op0, m_And(m_Value(A), m_Value(B))) &&
6106 match(Op1, m_And(m_Value(C), m_Value(D)))) {
6107 Value *X = 0, *Y = 0, *Z = 0;
6108
6109 if (A == C) {
6110 X = B; Y = D; Z = A;
6111 } else if (A == D) {
6112 X = B; Y = C; Z = A;
6113 } else if (B == C) {
6114 X = A; Y = D; Z = B;
6115 } else if (B == D) {
6116 X = A; Y = C; Z = B;
6117 }
6118
6119 if (X) { // Build (X^Y) & Z
6120 Op1 = InsertNewInstBefore(BinaryOperator::createXor(X, Y, "tmp"), I);
6121 Op1 = InsertNewInstBefore(BinaryOperator::createAnd(Op1, Z, "tmp"), I);
6122 I.setOperand(0, Op1);
6123 I.setOperand(1, Constant::getNullValue(Op1->getType()));
6124 return &I;
6125 }
6126 }
Chris Lattnerf5c8a0b2006-02-27 01:44:11 +00006127 }
Chris Lattner113f4f42002-06-25 16:13:24 +00006128 return Changed ? &I : 0;
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00006129}
6130
Reid Spencer266e42b2006-12-23 06:05:41 +00006131// visitICmpInstWithCastAndCast - Handle icmp (cast x to y), (cast/cst).
Chris Lattnerd1f46d32005-04-24 06:59:08 +00006132// We only handle extending casts so far.
6133//
Reid Spencer266e42b2006-12-23 06:05:41 +00006134Instruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) {
6135 const CastInst *LHSCI = cast<CastInst>(ICI.getOperand(0));
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006136 Value *LHSCIOp = LHSCI->getOperand(0);
6137 const Type *SrcTy = LHSCIOp->getType();
Reid Spencer266e42b2006-12-23 06:05:41 +00006138 const Type *DestTy = LHSCI->getType();
Chris Lattnerd1f46d32005-04-24 06:59:08 +00006139 Value *RHSCIOp;
6140
Reid Spencer266e42b2006-12-23 06:05:41 +00006141 // We only handle extension cast instructions, so far. Enforce this.
6142 if (LHSCI->getOpcode() != Instruction::ZExt &&
6143 LHSCI->getOpcode() != Instruction::SExt)
Chris Lattner03f06f12005-01-17 03:20:02 +00006144 return 0;
6145
Reid Spencer266e42b2006-12-23 06:05:41 +00006146 bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt;
6147 bool isSignedCmp = ICI.isSignedPredicate();
Chris Lattnerd1f46d32005-04-24 06:59:08 +00006148
Reid Spencer266e42b2006-12-23 06:05:41 +00006149 if (CastInst *CI = dyn_cast<CastInst>(ICI.getOperand(1))) {
Chris Lattnerd1f46d32005-04-24 06:59:08 +00006150 // Not an extension from the same type?
6151 RHSCIOp = CI->getOperand(0);
Reid Spencer266e42b2006-12-23 06:05:41 +00006152 if (RHSCIOp->getType() != LHSCIOp->getType())
6153 return 0;
Chris Lattner387bf3f2007-01-13 23:11:38 +00006154
6155 // If the signedness of the two compares doesn't agree (i.e. one is a sext
6156 // and the other is a zext), then we can't handle this.
6157 if (CI->getOpcode() != LHSCI->getOpcode())
6158 return 0;
6159
6160 // Likewise, if the signedness of the [sz]exts and the compare don't match,
6161 // then we can't handle this.
6162 if (isSignedExt != isSignedCmp && !ICI.isEquality())
6163 return 0;
6164
6165 // Okay, just insert a compare of the reduced operands now!
6166 return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
Reid Spencer279fa252004-11-28 21:31:15 +00006167 }
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00006168
Reid Spencer266e42b2006-12-23 06:05:41 +00006169 // If we aren't dealing with a constant on the RHS, exit early
6170 ConstantInt *CI = dyn_cast<ConstantInt>(ICI.getOperand(1));
6171 if (!CI)
6172 return 0;
6173
6174 // Compute the constant that would happen if we truncated to SrcTy then
6175 // reextended to DestTy.
6176 Constant *Res1 = ConstantExpr::getTrunc(CI, SrcTy);
6177 Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(), Res1, DestTy);
6178
6179 // If the re-extended constant didn't change...
6180 if (Res2 == CI) {
6181 // Make sure that sign of the Cmp and the sign of the Cast are the same.
6182 // For example, we might have:
6183 // %A = sext short %X to uint
6184 // %B = icmp ugt uint %A, 1330
6185 // It is incorrect to transform this into
6186 // %B = icmp ugt short %X, 1330
6187 // because %A may have negative value.
6188 //
6189 // However, it is OK if SrcTy is bool (See cast-set.ll testcase)
6190 // OR operation is EQ/NE.
Reid Spencer542964f2007-01-11 18:21:29 +00006191 if (isSignedExt == isSignedCmp || SrcTy == Type::Int1Ty || ICI.isEquality())
Reid Spencer266e42b2006-12-23 06:05:41 +00006192 return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
6193 else
6194 return 0;
6195 }
6196
6197 // The re-extended constant changed so the constant cannot be represented
6198 // in the shorter type. Consequently, we cannot emit a simple comparison.
6199
6200 // First, handle some easy cases. We know the result cannot be equal at this
6201 // point so handle the ICI.isEquality() cases
6202 if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
Zhou Sheng75b871f2007-01-11 12:24:14 +00006203 return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
Reid Spencer266e42b2006-12-23 06:05:41 +00006204 if (ICI.getPredicate() == ICmpInst::ICMP_NE)
Zhou Sheng75b871f2007-01-11 12:24:14 +00006205 return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
Reid Spencer266e42b2006-12-23 06:05:41 +00006206
6207 // Evaluate the comparison for LT (we invert for GT below). LE and GE cases
6208 // should have been folded away previously and not enter in here.
6209 Value *Result;
6210 if (isSignedCmp) {
6211 // We're performing a signed comparison.
6212 if (cast<ConstantInt>(CI)->getSExtValue() < 0)
Zhou Sheng75b871f2007-01-11 12:24:14 +00006213 Result = ConstantInt::getFalse(); // X < (small) --> false
Reid Spencer266e42b2006-12-23 06:05:41 +00006214 else
Zhou Sheng75b871f2007-01-11 12:24:14 +00006215 Result = ConstantInt::getTrue(); // X < (large) --> true
Reid Spencer266e42b2006-12-23 06:05:41 +00006216 } else {
6217 // We're performing an unsigned comparison.
6218 if (isSignedExt) {
6219 // We're performing an unsigned comp with a sign extended value.
6220 // This is true if the input is >= 0. [aka >s -1]
Zhou Sheng75b871f2007-01-11 12:24:14 +00006221 Constant *NegOne = ConstantInt::getAllOnesValue(SrcTy);
Reid Spencer266e42b2006-12-23 06:05:41 +00006222 Result = InsertNewInstBefore(new ICmpInst(ICmpInst::ICMP_SGT, LHSCIOp,
6223 NegOne, ICI.getName()), ICI);
6224 } else {
6225 // Unsigned extend & unsigned compare -> always true.
Zhou Sheng75b871f2007-01-11 12:24:14 +00006226 Result = ConstantInt::getTrue();
Reid Spencer266e42b2006-12-23 06:05:41 +00006227 }
6228 }
6229
6230 // Finally, return the value computed.
6231 if (ICI.getPredicate() == ICmpInst::ICMP_ULT ||
6232 ICI.getPredicate() == ICmpInst::ICMP_SLT) {
6233 return ReplaceInstUsesWith(ICI, Result);
6234 } else {
6235 assert((ICI.getPredicate()==ICmpInst::ICMP_UGT ||
6236 ICI.getPredicate()==ICmpInst::ICMP_SGT) &&
6237 "ICmp should be folded!");
6238 if (Constant *CI = dyn_cast<Constant>(Result))
6239 return ReplaceInstUsesWith(ICI, ConstantExpr::getNot(CI));
6240 else
6241 return BinaryOperator::createNot(Result);
6242 }
Chris Lattnerd1f46d32005-04-24 06:59:08 +00006243}
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00006244
Reid Spencer2341c222007-02-02 02:16:23 +00006245Instruction *InstCombiner::visitShl(BinaryOperator &I) {
6246 return commonShiftTransforms(I);
6247}
6248
6249Instruction *InstCombiner::visitLShr(BinaryOperator &I) {
6250 return commonShiftTransforms(I);
6251}
6252
6253Instruction *InstCombiner::visitAShr(BinaryOperator &I) {
6254 return commonShiftTransforms(I);
6255}
6256
6257Instruction *InstCombiner::commonShiftTransforms(BinaryOperator &I) {
6258 assert(I.getOperand(1)->getType() == I.getOperand(0)->getType());
Chris Lattner113f4f42002-06-25 16:13:24 +00006259 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00006260
6261 // shl X, 0 == X and shr X, 0 == X
6262 // shl 0, X == 0 and shr 0, X == 0
Reid Spencer2341c222007-02-02 02:16:23 +00006263 if (Op1 == Constant::getNullValue(Op1->getType()) ||
Chris Lattnere6794492002-08-12 21:17:25 +00006264 Op0 == Constant::getNullValue(Op0->getType()))
6265 return ReplaceInstUsesWith(I, Op0);
Chris Lattnerf5b4ef72006-02-12 08:07:37 +00006266
Reid Spencer266e42b2006-12-23 06:05:41 +00006267 if (isa<UndefValue>(Op0)) {
6268 if (I.getOpcode() == Instruction::AShr) // undef >>s X -> undef
Chris Lattner67f05452004-10-16 23:28:04 +00006269 return ReplaceInstUsesWith(I, Op0);
Reid Spencer266e42b2006-12-23 06:05:41 +00006270 else // undef << X -> 0, undef >>u X -> 0
Chris Lattner81a7a232004-10-16 18:11:37 +00006271 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
6272 }
6273 if (isa<UndefValue>(Op1)) {
Reid Spencer266e42b2006-12-23 06:05:41 +00006274 if (I.getOpcode() == Instruction::AShr) // X >>s undef -> X
6275 return ReplaceInstUsesWith(I, Op0);
6276 else // X << undef, X >>u undef -> 0
Chris Lattner81a7a232004-10-16 18:11:37 +00006277 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
Chris Lattner81a7a232004-10-16 18:11:37 +00006278 }
6279
Chris Lattnerd4dee402006-11-10 23:38:52 +00006280 // ashr int -1, X = -1 (for any arithmetic shift rights of ~0)
6281 if (I.getOpcode() == Instruction::AShr)
Reid Spencere0fc4df2006-10-20 07:07:24 +00006282 if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
Chris Lattnerd4dee402006-11-10 23:38:52 +00006283 if (CSI->isAllOnesValue())
Chris Lattnerdeaa0dd2003-08-12 21:53:41 +00006284 return ReplaceInstUsesWith(I, CSI);
6285
Chris Lattner183b3362004-04-09 19:05:30 +00006286 // Try to fold constant and into select arguments.
6287 if (isa<Constant>(Op0))
6288 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
Chris Lattner86102b82005-01-01 16:22:27 +00006289 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
Chris Lattner183b3362004-04-09 19:05:30 +00006290 return R;
6291
Chris Lattnerb18dbbf2005-05-08 17:34:56 +00006292 // See if we can turn a signed shr into an unsigned shr.
Chris Lattnerb3f24c92006-09-18 04:22:48 +00006293 if (I.isArithmeticShift()) {
Chris Lattnerc3ebf402006-02-07 07:27:52 +00006294 if (MaskedValueIsZero(Op0,
6295 1ULL << (I.getType()->getPrimitiveSizeInBits()-1))) {
Reid Spencer0d5f9232007-02-02 14:08:20 +00006296 return BinaryOperator::createLShr(Op0, Op1, I.getName());
Chris Lattnerb18dbbf2005-05-08 17:34:56 +00006297 }
6298 }
Jeff Cohen5f4ef3c2005-07-27 06:12:32 +00006299
Reid Spencere0fc4df2006-10-20 07:07:24 +00006300 if (ConstantInt *CUI = dyn_cast<ConstantInt>(Op1))
Reid Spencerc635f472006-12-31 05:48:39 +00006301 if (Instruction *Res = FoldShiftByConstant(Op0, CUI, I))
6302 return Res;
Chris Lattner14553932006-01-06 07:12:35 +00006303 return 0;
6304}
6305
Reid Spencere0fc4df2006-10-20 07:07:24 +00006306Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
Reid Spencer2341c222007-02-02 02:16:23 +00006307 BinaryOperator &I) {
Reid Spencer266e42b2006-12-23 06:05:41 +00006308 bool isLeftShift = I.getOpcode() == Instruction::Shl;
Chris Lattner14553932006-01-06 07:12:35 +00006309
Chris Lattnerf5b4ef72006-02-12 08:07:37 +00006310 // See if we can simplify any instructions used by the instruction whose sole
6311 // purpose is to compute bits we don't care about.
6312 uint64_t KnownZero, KnownOne;
Reid Spencera94d3942007-01-19 21:13:56 +00006313 if (SimplifyDemandedBits(&I, cast<IntegerType>(I.getType())->getBitMask(),
Chris Lattnerf5b4ef72006-02-12 08:07:37 +00006314 KnownZero, KnownOne))
6315 return &I;
6316
Chris Lattner14553932006-01-06 07:12:35 +00006317 // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
6318 // of a signed value.
6319 //
6320 unsigned TypeBits = Op0->getType()->getPrimitiveSizeInBits();
Reid Spencere0fc4df2006-10-20 07:07:24 +00006321 if (Op1->getZExtValue() >= TypeBits) {
Chris Lattnerd5fea612007-02-02 05:29:55 +00006322 if (I.getOpcode() != Instruction::AShr)
Chris Lattner14553932006-01-06 07:12:35 +00006323 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
6324 else {
Chris Lattnerd5fea612007-02-02 05:29:55 +00006325 I.setOperand(1, ConstantInt::get(I.getType(), TypeBits-1));
Chris Lattner14553932006-01-06 07:12:35 +00006326 return &I;
Chris Lattnerf5ce2542004-02-23 20:30:06 +00006327 }
Chris Lattner14553932006-01-06 07:12:35 +00006328 }
6329
6330 // ((X*C1) << C2) == (X * (C1 << C2))
6331 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
6332 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
6333 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
6334 return BinaryOperator::createMul(BO->getOperand(0),
6335 ConstantExpr::getShl(BOOp, Op1));
6336
6337 // Try to fold constant and into select arguments.
6338 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
6339 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
6340 return R;
6341 if (isa<PHINode>(Op0))
6342 if (Instruction *NV = FoldOpIntoPhi(I))
6343 return NV;
6344
6345 if (Op0->hasOneUse()) {
Chris Lattner14553932006-01-06 07:12:35 +00006346 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
6347 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
6348 Value *V1, *V2;
6349 ConstantInt *CC;
6350 switch (Op0BO->getOpcode()) {
Chris Lattner27cb9db2005-09-18 05:12:10 +00006351 default: break;
6352 case Instruction::Add:
6353 case Instruction::And:
6354 case Instruction::Or:
Reid Spencer2f34b982007-02-02 14:41:37 +00006355 case Instruction::Xor: {
Chris Lattner27cb9db2005-09-18 05:12:10 +00006356 // These operators commute.
6357 // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
Chris Lattner797dee72005-09-18 06:30:59 +00006358 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
6359 match(Op0BO->getOperand(1),
Chris Lattner14553932006-01-06 07:12:35 +00006360 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == Op1) {
Reid Spencer0d5f9232007-02-02 14:08:20 +00006361 Instruction *YS = BinaryOperator::createShl(
Chris Lattner14553932006-01-06 07:12:35 +00006362 Op0BO->getOperand(0), Op1,
Chris Lattner797dee72005-09-18 06:30:59 +00006363 Op0BO->getName());
6364 InsertNewInstBefore(YS, I); // (Y << C)
Chris Lattner24cd2fa2006-02-09 07:41:14 +00006365 Instruction *X =
6366 BinaryOperator::create(Op0BO->getOpcode(), YS, V1,
6367 Op0BO->getOperand(1)->getName());
Chris Lattner797dee72005-09-18 06:30:59 +00006368 InsertNewInstBefore(X, I); // (X + (Y << C))
6369 Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
Chris Lattner14553932006-01-06 07:12:35 +00006370 C2 = ConstantExpr::getShl(C2, Op1);
Chris Lattner797dee72005-09-18 06:30:59 +00006371 return BinaryOperator::createAnd(X, C2);
6372 }
Chris Lattner14553932006-01-06 07:12:35 +00006373
Chris Lattner797dee72005-09-18 06:30:59 +00006374 // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
Reid Spencer2f34b982007-02-02 14:41:37 +00006375 Value *Op0BOOp1 = Op0BO->getOperand(1);
Chris Lattnerfe53cf22007-03-05 00:11:19 +00006376 if (isLeftShift && Op0BOOp1->hasOneUse() &&
Reid Spencer2f34b982007-02-02 14:41:37 +00006377 match(Op0BOOp1,
6378 m_And(m_Shr(m_Value(V1), m_Value(V2)),m_ConstantInt(CC))) &&
Chris Lattnerfe53cf22007-03-05 00:11:19 +00006379 cast<BinaryOperator>(Op0BOOp1)->getOperand(0)->hasOneUse() &&
6380 V2 == Op1) {
Reid Spencer0d5f9232007-02-02 14:08:20 +00006381 Instruction *YS = BinaryOperator::createShl(
Reid Spencer2341c222007-02-02 02:16:23 +00006382 Op0BO->getOperand(0), Op1,
6383 Op0BO->getName());
Chris Lattner797dee72005-09-18 06:30:59 +00006384 InsertNewInstBefore(YS, I); // (Y << C)
6385 Instruction *XM =
Chris Lattner14553932006-01-06 07:12:35 +00006386 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, Op1),
Chris Lattner797dee72005-09-18 06:30:59 +00006387 V1->getName()+".mask");
6388 InsertNewInstBefore(XM, I); // X & (CC << C)
6389
6390 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
6391 }
Reid Spencer2f34b982007-02-02 14:41:37 +00006392 }
Chris Lattner14553932006-01-06 07:12:35 +00006393
Reid Spencer2f34b982007-02-02 14:41:37 +00006394 // FALL THROUGH.
6395 case Instruction::Sub: {
Chris Lattner27cb9db2005-09-18 05:12:10 +00006396 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
Chris Lattner797dee72005-09-18 06:30:59 +00006397 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
6398 match(Op0BO->getOperand(0),
Chris Lattner14553932006-01-06 07:12:35 +00006399 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == Op1) {
Reid Spencer0d5f9232007-02-02 14:08:20 +00006400 Instruction *YS = BinaryOperator::createShl(
Reid Spencer2341c222007-02-02 02:16:23 +00006401 Op0BO->getOperand(1), Op1,
6402 Op0BO->getName());
Chris Lattner797dee72005-09-18 06:30:59 +00006403 InsertNewInstBefore(YS, I); // (Y << C)
Chris Lattner24cd2fa2006-02-09 07:41:14 +00006404 Instruction *X =
Chris Lattner1df0e982006-05-31 21:14:00 +00006405 BinaryOperator::create(Op0BO->getOpcode(), V1, YS,
Chris Lattner24cd2fa2006-02-09 07:41:14 +00006406 Op0BO->getOperand(0)->getName());
Chris Lattner797dee72005-09-18 06:30:59 +00006407 InsertNewInstBefore(X, I); // (X + (Y << C))
6408 Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
Chris Lattner14553932006-01-06 07:12:35 +00006409 C2 = ConstantExpr::getShl(C2, Op1);
Chris Lattner797dee72005-09-18 06:30:59 +00006410 return BinaryOperator::createAnd(X, C2);
6411 }
Chris Lattner14553932006-01-06 07:12:35 +00006412
Chris Lattner1df0e982006-05-31 21:14:00 +00006413 // Turn (((X >> C)&CC) + Y) << C -> (X + (Y << C)) & (CC << C)
Chris Lattner797dee72005-09-18 06:30:59 +00006414 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
6415 match(Op0BO->getOperand(0),
6416 m_And(m_Shr(m_Value(V1), m_Value(V2)),
Chris Lattner14553932006-01-06 07:12:35 +00006417 m_ConstantInt(CC))) && V2 == Op1 &&
Chris Lattner24cd2fa2006-02-09 07:41:14 +00006418 cast<BinaryOperator>(Op0BO->getOperand(0))
6419 ->getOperand(0)->hasOneUse()) {
Reid Spencer0d5f9232007-02-02 14:08:20 +00006420 Instruction *YS = BinaryOperator::createShl(
Reid Spencer2341c222007-02-02 02:16:23 +00006421 Op0BO->getOperand(1), Op1,
6422 Op0BO->getName());
Chris Lattner797dee72005-09-18 06:30:59 +00006423 InsertNewInstBefore(YS, I); // (Y << C)
6424 Instruction *XM =
Chris Lattner14553932006-01-06 07:12:35 +00006425 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, Op1),
Chris Lattner797dee72005-09-18 06:30:59 +00006426 V1->getName()+".mask");
6427 InsertNewInstBefore(XM, I); // X & (CC << C)
6428
Chris Lattner1df0e982006-05-31 21:14:00 +00006429 return BinaryOperator::create(Op0BO->getOpcode(), XM, YS);
Chris Lattner797dee72005-09-18 06:30:59 +00006430 }
Chris Lattner14553932006-01-06 07:12:35 +00006431
Chris Lattner27cb9db2005-09-18 05:12:10 +00006432 break;
Reid Spencer2f34b982007-02-02 14:41:37 +00006433 }
Chris Lattner14553932006-01-06 07:12:35 +00006434 }
6435
6436
6437 // If the operand is an bitwise operator with a constant RHS, and the
6438 // shift is the only use, we can pull it out of the shift.
6439 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
6440 bool isValid = true; // Valid only for And, Or, Xor
6441 bool highBitSet = false; // Transform if high bit of constant set?
6442
6443 switch (Op0BO->getOpcode()) {
Chris Lattnerdeaa0dd2003-08-12 21:53:41 +00006444 default: isValid = false; break; // Do not perform transform!
Chris Lattner44bd3922004-10-08 03:46:20 +00006445 case Instruction::Add:
6446 isValid = isLeftShift;
6447 break;
Chris Lattnerdeaa0dd2003-08-12 21:53:41 +00006448 case Instruction::Or:
6449 case Instruction::Xor:
6450 highBitSet = false;
6451 break;
6452 case Instruction::And:
6453 highBitSet = true;
6454 break;
Chris Lattner14553932006-01-06 07:12:35 +00006455 }
6456
6457 // If this is a signed shift right, and the high bit is modified
6458 // by the logical operation, do not perform the transformation.
6459 // The highBitSet boolean indicates the value of the high bit of
6460 // the constant which would cause it to be modified for this
6461 // operation.
6462 //
Chris Lattner3e009e82007-02-05 00:57:54 +00006463 if (isValid && !isLeftShift && I.getOpcode() == Instruction::AShr) {
Reid Spencere0fc4df2006-10-20 07:07:24 +00006464 uint64_t Val = Op0C->getZExtValue();
Chris Lattner14553932006-01-06 07:12:35 +00006465 isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet;
6466 }
6467
6468 if (isValid) {
6469 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, Op1);
6470
6471 Instruction *NewShift =
Chris Lattner6e0123b2007-02-11 01:23:03 +00006472 BinaryOperator::create(I.getOpcode(), Op0BO->getOperand(0), Op1);
Chris Lattner14553932006-01-06 07:12:35 +00006473 InsertNewInstBefore(NewShift, I);
Chris Lattner6e0123b2007-02-11 01:23:03 +00006474 NewShift->takeName(Op0BO);
Chris Lattner14553932006-01-06 07:12:35 +00006475
6476 return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
6477 NewRHS);
6478 }
6479 }
6480 }
6481 }
6482
Chris Lattnereb372a02006-01-06 07:52:12 +00006483 // Find out if this is a shift of a shift by a constant.
Reid Spencer2341c222007-02-02 02:16:23 +00006484 BinaryOperator *ShiftOp = dyn_cast<BinaryOperator>(Op0);
6485 if (ShiftOp && !ShiftOp->isShift())
6486 ShiftOp = 0;
Chris Lattnereb372a02006-01-06 07:52:12 +00006487
Reid Spencere0fc4df2006-10-20 07:07:24 +00006488 if (ShiftOp && isa<ConstantInt>(ShiftOp->getOperand(1))) {
Reid Spencere0fc4df2006-10-20 07:07:24 +00006489 ConstantInt *ShiftAmt1C = cast<ConstantInt>(ShiftOp->getOperand(1));
Reid Spencere0fc4df2006-10-20 07:07:24 +00006490 unsigned ShiftAmt1 = (unsigned)ShiftAmt1C->getZExtValue();
6491 unsigned ShiftAmt2 = (unsigned)Op1->getZExtValue();
Chris Lattner3e009e82007-02-05 00:57:54 +00006492 assert(ShiftAmt2 != 0 && "Should have been simplified earlier");
6493 if (ShiftAmt1 == 0) return 0; // Will be simplified in the future.
6494 Value *X = ShiftOp->getOperand(0);
Chris Lattnereb372a02006-01-06 07:52:12 +00006495
Chris Lattner3e009e82007-02-05 00:57:54 +00006496 unsigned AmtSum = ShiftAmt1+ShiftAmt2; // Fold into one big shift.
6497 if (AmtSum > I.getType()->getPrimitiveSizeInBits())
6498 AmtSum = I.getType()->getPrimitiveSizeInBits();
6499
6500 const IntegerType *Ty = cast<IntegerType>(I.getType());
6501
6502 // Check for (X << c1) << c2 and (X >> c1) >> c2
Chris Lattner6c344e52007-02-03 23:28:07 +00006503 if (I.getOpcode() == ShiftOp->getOpcode()) {
Chris Lattner3e009e82007-02-05 00:57:54 +00006504 return BinaryOperator::create(I.getOpcode(), X,
6505 ConstantInt::get(Ty, AmtSum));
6506 } else if (ShiftOp->getOpcode() == Instruction::LShr &&
6507 I.getOpcode() == Instruction::AShr) {
6508 // ((X >>u C1) >>s C2) -> (X >>u (C1+C2)) since C1 != 0.
6509 return BinaryOperator::createLShr(X, ConstantInt::get(Ty, AmtSum));
6510 } else if (ShiftOp->getOpcode() == Instruction::AShr &&
6511 I.getOpcode() == Instruction::LShr) {
6512 // ((X >>s C1) >>u C2) -> ((X >>s (C1+C2)) & mask) since C1 != 0.
6513 Instruction *Shift =
6514 BinaryOperator::createAShr(X, ConstantInt::get(Ty, AmtSum));
6515 InsertNewInstBefore(Shift, I);
6516
6517 uint64_t Mask = Ty->getBitMask() >> ShiftAmt2;
6518 return BinaryOperator::createAnd(Shift, ConstantInt::get(Ty, Mask));
Chris Lattnereb372a02006-01-06 07:52:12 +00006519 }
6520
Chris Lattner3e009e82007-02-05 00:57:54 +00006521 // Okay, if we get here, one shift must be left, and the other shift must be
6522 // right. See if the amounts are equal.
6523 if (ShiftAmt1 == ShiftAmt2) {
6524 // If we have ((X >>? C) << C), turn this into X & (-1 << C).
6525 if (I.getOpcode() == Instruction::Shl) {
Chris Lattner0a28e902007-02-05 04:09:35 +00006526 uint64_t Mask = Ty->getBitMask() << ShiftAmt1;
Chris Lattner3e009e82007-02-05 00:57:54 +00006527 return BinaryOperator::createAnd(X, ConstantInt::get(Ty, Mask));
6528 }
6529 // If we have ((X << C) >>u C), turn this into X & (-1 >>u C).
6530 if (I.getOpcode() == Instruction::LShr) {
Chris Lattner0a28e902007-02-05 04:09:35 +00006531 uint64_t Mask = Ty->getBitMask() >> ShiftAmt1;
Chris Lattner3e009e82007-02-05 00:57:54 +00006532 return BinaryOperator::createAnd(X, ConstantInt::get(Ty, Mask));
6533 }
6534 // We can simplify ((X << C) >>s C) into a trunc + sext.
6535 // NOTE: we could do this for any C, but that would make 'unusual' integer
6536 // types. For now, just stick to ones well-supported by the code
6537 // generators.
6538 const Type *SExtType = 0;
6539 switch (Ty->getBitWidth() - ShiftAmt1) {
6540 case 8 : SExtType = Type::Int8Ty; break;
6541 case 16: SExtType = Type::Int16Ty; break;
6542 case 32: SExtType = Type::Int32Ty; break;
6543 default: break;
6544 }
6545 if (SExtType) {
6546 Instruction *NewTrunc = new TruncInst(X, SExtType, "sext");
6547 InsertNewInstBefore(NewTrunc, I);
6548 return new SExtInst(NewTrunc, Ty);
6549 }
6550 // Otherwise, we can't handle it yet.
6551 } else if (ShiftAmt1 < ShiftAmt2) {
6552 unsigned ShiftDiff = ShiftAmt2-ShiftAmt1;
Chris Lattnereb372a02006-01-06 07:52:12 +00006553
Chris Lattner83ac5ae92007-02-05 05:57:49 +00006554 // (X >>? C1) << C2 --> X << (C2-C1) & (-1 << C2)
Chris Lattner3e009e82007-02-05 00:57:54 +00006555 if (I.getOpcode() == Instruction::Shl) {
6556 assert(ShiftOp->getOpcode() == Instruction::LShr ||
6557 ShiftOp->getOpcode() == Instruction::AShr);
Chris Lattner9cbfbc22006-01-07 01:32:28 +00006558 Instruction *Shift =
Chris Lattner3e009e82007-02-05 00:57:54 +00006559 BinaryOperator::createShl(X, ConstantInt::get(Ty, ShiftDiff));
Chris Lattner9cbfbc22006-01-07 01:32:28 +00006560 InsertNewInstBefore(Shift, I);
6561
Chris Lattner83ac5ae92007-02-05 05:57:49 +00006562 uint64_t Mask = Ty->getBitMask() << ShiftAmt2;
Chris Lattner3e009e82007-02-05 00:57:54 +00006563 return BinaryOperator::createAnd(Shift, ConstantInt::get(Ty, Mask));
Chris Lattnereb372a02006-01-06 07:52:12 +00006564 }
Chris Lattner3e009e82007-02-05 00:57:54 +00006565
Chris Lattner83ac5ae92007-02-05 05:57:49 +00006566 // (X << C1) >>u C2 --> X >>u (C2-C1) & (-1 >> C2)
Chris Lattner3e009e82007-02-05 00:57:54 +00006567 if (I.getOpcode() == Instruction::LShr) {
6568 assert(ShiftOp->getOpcode() == Instruction::Shl);
6569 Instruction *Shift =
6570 BinaryOperator::createLShr(X, ConstantInt::get(Ty, ShiftDiff));
6571 InsertNewInstBefore(Shift, I);
Chris Lattnereb372a02006-01-06 07:52:12 +00006572
Chris Lattner83ac5ae92007-02-05 05:57:49 +00006573 uint64_t Mask = Ty->getBitMask() >> ShiftAmt2;
Chris Lattner3e009e82007-02-05 00:57:54 +00006574 return BinaryOperator::createAnd(Shift, ConstantInt::get(Ty, Mask));
Chris Lattner27cb9db2005-09-18 05:12:10 +00006575 }
Chris Lattner3e009e82007-02-05 00:57:54 +00006576
6577 // We can't handle (X << C1) >>s C2, it shifts arbitrary bits in.
6578 } else {
6579 assert(ShiftAmt2 < ShiftAmt1);
6580 unsigned ShiftDiff = ShiftAmt1-ShiftAmt2;
6581
Chris Lattner83ac5ae92007-02-05 05:57:49 +00006582 // (X >>? C1) << C2 --> X >>? (C1-C2) & (-1 << C2)
Chris Lattner3e009e82007-02-05 00:57:54 +00006583 if (I.getOpcode() == Instruction::Shl) {
6584 assert(ShiftOp->getOpcode() == Instruction::LShr ||
6585 ShiftOp->getOpcode() == Instruction::AShr);
6586 Instruction *Shift =
6587 BinaryOperator::create(ShiftOp->getOpcode(), X,
6588 ConstantInt::get(Ty, ShiftDiff));
6589 InsertNewInstBefore(Shift, I);
6590
6591 uint64_t Mask = Ty->getBitMask() << ShiftAmt2;
6592 return BinaryOperator::createAnd(Shift, ConstantInt::get(Ty, Mask));
6593 }
6594
Chris Lattner83ac5ae92007-02-05 05:57:49 +00006595 // (X << C1) >>u C2 --> X << (C1-C2) & (-1 >> C2)
Chris Lattner3e009e82007-02-05 00:57:54 +00006596 if (I.getOpcode() == Instruction::LShr) {
6597 assert(ShiftOp->getOpcode() == Instruction::Shl);
6598 Instruction *Shift =
6599 BinaryOperator::createShl(X, ConstantInt::get(Ty, ShiftDiff));
6600 InsertNewInstBefore(Shift, I);
6601
6602 uint64_t Mask = Ty->getBitMask() >> ShiftAmt2;
6603 return BinaryOperator::createAnd(Shift, ConstantInt::get(Ty, Mask));
6604 }
6605
6606 // We can't handle (X << C1) >>a C2, it shifts arbitrary bits in.
Chris Lattner86102b82005-01-01 16:22:27 +00006607 }
Chris Lattnereb372a02006-01-06 07:52:12 +00006608 }
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00006609 return 0;
6610}
6611
Chris Lattner48a44f72002-05-02 17:06:02 +00006612
Chris Lattner8f663e82005-10-29 04:36:15 +00006613/// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear
6614/// expression. If so, decompose it, returning some value X, such that Val is
6615/// X*Scale+Offset.
6616///
6617static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
6618 unsigned &Offset) {
Reid Spencerc635f472006-12-31 05:48:39 +00006619 assert(Val->getType() == Type::Int32Ty && "Unexpected allocation size type!");
Reid Spencere0fc4df2006-10-20 07:07:24 +00006620 if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) {
Reid Spencerc635f472006-12-31 05:48:39 +00006621 Offset = CI->getZExtValue();
6622 Scale = 1;
6623 return ConstantInt::get(Type::Int32Ty, 0);
Chris Lattner8f663e82005-10-29 04:36:15 +00006624 } else if (Instruction *I = dyn_cast<Instruction>(Val)) {
6625 if (I->getNumOperands() == 2) {
Reid Spencere0fc4df2006-10-20 07:07:24 +00006626 if (ConstantInt *CUI = dyn_cast<ConstantInt>(I->getOperand(1))) {
Reid Spencerc635f472006-12-31 05:48:39 +00006627 if (I->getOpcode() == Instruction::Shl) {
6628 // This is a value scaled by '1 << the shift amt'.
6629 Scale = 1U << CUI->getZExtValue();
6630 Offset = 0;
6631 return I->getOperand(0);
6632 } else if (I->getOpcode() == Instruction::Mul) {
6633 // This value is scaled by 'CUI'.
6634 Scale = CUI->getZExtValue();
6635 Offset = 0;
6636 return I->getOperand(0);
6637 } else if (I->getOpcode() == Instruction::Add) {
6638 // We have X+C. Check to see if we really have (X*C2)+C1,
6639 // where C1 is divisible by C2.
6640 unsigned SubScale;
6641 Value *SubVal =
6642 DecomposeSimpleLinearExpr(I->getOperand(0), SubScale, Offset);
6643 Offset += CUI->getZExtValue();
6644 if (SubScale > 1 && (Offset % SubScale == 0)) {
6645 Scale = SubScale;
6646 return SubVal;
Chris Lattner8f663e82005-10-29 04:36:15 +00006647 }
6648 }
6649 }
6650 }
6651 }
6652
6653 // Otherwise, we can't look past this.
6654 Scale = 1;
6655 Offset = 0;
6656 return Val;
6657}
6658
6659
Chris Lattner216be912005-10-24 06:03:58 +00006660/// PromoteCastOfAllocation - If we find a cast of an allocation instruction,
6661/// try to eliminate the cast by moving the type information into the alloc.
6662Instruction *InstCombiner::PromoteCastOfAllocation(CastInst &CI,
6663 AllocationInst &AI) {
6664 const PointerType *PTy = dyn_cast<PointerType>(CI.getType());
Chris Lattnerbb171802005-10-27 05:53:56 +00006665 if (!PTy) return 0; // Not casting the allocation to a pointer type.
Chris Lattner216be912005-10-24 06:03:58 +00006666
Chris Lattnerac87beb2005-10-24 06:22:12 +00006667 // Remove any uses of AI that are dead.
6668 assert(!CI.use_empty() && "Dead instructions should be removed earlier!");
Chris Lattner99c6cf62007-02-15 22:52:10 +00006669
Chris Lattnerac87beb2005-10-24 06:22:12 +00006670 for (Value::use_iterator UI = AI.use_begin(), E = AI.use_end(); UI != E; ) {
6671 Instruction *User = cast<Instruction>(*UI++);
6672 if (isInstructionTriviallyDead(User)) {
6673 while (UI != E && *UI == User)
6674 ++UI; // If this instruction uses AI more than once, don't break UI.
6675
Chris Lattnerac87beb2005-10-24 06:22:12 +00006676 ++NumDeadInst;
Bill Wendling5dbf43c2006-11-26 09:46:52 +00006677 DOUT << "IC: DCE: " << *User;
Chris Lattner51f54572007-03-02 19:59:19 +00006678 EraseInstFromFunction(*User);
Chris Lattnerac87beb2005-10-24 06:22:12 +00006679 }
6680 }
6681
Chris Lattner216be912005-10-24 06:03:58 +00006682 // Get the type really allocated and the type casted to.
6683 const Type *AllocElTy = AI.getAllocatedType();
6684 const Type *CastElTy = PTy->getElementType();
6685 if (!AllocElTy->isSized() || !CastElTy->isSized()) return 0;
Chris Lattner355ecc02005-10-24 06:26:18 +00006686
Chris Lattner945e4372007-02-14 05:52:17 +00006687 unsigned AllocElTyAlign = TD->getABITypeAlignment(AllocElTy);
6688 unsigned CastElTyAlign = TD->getABITypeAlignment(CastElTy);
Chris Lattner355ecc02005-10-24 06:26:18 +00006689 if (CastElTyAlign < AllocElTyAlign) return 0;
6690
Chris Lattner46705b22005-10-24 06:35:18 +00006691 // If the allocation has multiple uses, only promote it if we are strictly
6692 // increasing the alignment of the resultant allocation. If we keep it the
6693 // same, we open the door to infinite loops of various kinds.
6694 if (!AI.hasOneUse() && CastElTyAlign == AllocElTyAlign) return 0;
6695
Chris Lattner216be912005-10-24 06:03:58 +00006696 uint64_t AllocElTySize = TD->getTypeSize(AllocElTy);
6697 uint64_t CastElTySize = TD->getTypeSize(CastElTy);
Chris Lattnerbb171802005-10-27 05:53:56 +00006698 if (CastElTySize == 0 || AllocElTySize == 0) return 0;
Chris Lattner355ecc02005-10-24 06:26:18 +00006699
Chris Lattner8270c332005-10-29 03:19:53 +00006700 // See if we can satisfy the modulus by pulling a scale out of the array
6701 // size argument.
Chris Lattner8f663e82005-10-29 04:36:15 +00006702 unsigned ArraySizeScale, ArrayOffset;
6703 Value *NumElements = // See if the array size is a decomposable linear expr.
6704 DecomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset);
6705
Chris Lattner8270c332005-10-29 03:19:53 +00006706 // If we can now satisfy the modulus, by using a non-1 scale, we really can
6707 // do the xform.
Chris Lattner8f663e82005-10-29 04:36:15 +00006708 if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
6709 (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return 0;
Chris Lattnerb3ecf962005-10-27 06:12:00 +00006710
Chris Lattner8270c332005-10-29 03:19:53 +00006711 unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
6712 Value *Amt = 0;
6713 if (Scale == 1) {
6714 Amt = NumElements;
6715 } else {
Reid Spencere0fc4df2006-10-20 07:07:24 +00006716 // If the allocation size is constant, form a constant mul expression
Reid Spencerc635f472006-12-31 05:48:39 +00006717 Amt = ConstantInt::get(Type::Int32Ty, Scale);
6718 if (isa<ConstantInt>(NumElements))
Reid Spencere0fc4df2006-10-20 07:07:24 +00006719 Amt = ConstantExpr::getMul(
6720 cast<ConstantInt>(NumElements), cast<ConstantInt>(Amt));
6721 // otherwise multiply the amount and the number of elements
Chris Lattner8270c332005-10-29 03:19:53 +00006722 else if (Scale != 1) {
6723 Instruction *Tmp = BinaryOperator::createMul(Amt, NumElements, "tmp");
6724 Amt = InsertNewInstBefore(Tmp, AI);
Chris Lattnerb3ecf962005-10-27 06:12:00 +00006725 }
Chris Lattnerbb171802005-10-27 05:53:56 +00006726 }
6727
Chris Lattner8f663e82005-10-29 04:36:15 +00006728 if (unsigned Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
Reid Spencerc635f472006-12-31 05:48:39 +00006729 Value *Off = ConstantInt::get(Type::Int32Ty, Offset);
Chris Lattner8f663e82005-10-29 04:36:15 +00006730 Instruction *Tmp = BinaryOperator::createAdd(Amt, Off, "tmp");
6731 Amt = InsertNewInstBefore(Tmp, AI);
6732 }
6733
Chris Lattner216be912005-10-24 06:03:58 +00006734 AllocationInst *New;
6735 if (isa<MallocInst>(AI))
Chris Lattner6e0123b2007-02-11 01:23:03 +00006736 New = new MallocInst(CastElTy, Amt, AI.getAlignment());
Chris Lattner216be912005-10-24 06:03:58 +00006737 else
Chris Lattner6e0123b2007-02-11 01:23:03 +00006738 New = new AllocaInst(CastElTy, Amt, AI.getAlignment());
Chris Lattner216be912005-10-24 06:03:58 +00006739 InsertNewInstBefore(New, AI);
Chris Lattner6e0123b2007-02-11 01:23:03 +00006740 New->takeName(&AI);
Chris Lattner46705b22005-10-24 06:35:18 +00006741
6742 // If the allocation has multiple uses, insert a cast and change all things
6743 // that used it to use the new cast. This will also hack on CI, but it will
6744 // die soon.
6745 if (!AI.hasOneUse()) {
6746 AddUsesToWorkList(AI);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006747 // New is the allocation instruction, pointer typed. AI is the original
6748 // allocation instruction, also pointer typed. Thus, cast to use is BitCast.
6749 CastInst *NewCast = new BitCastInst(New, AI.getType(), "tmpcast");
Chris Lattner46705b22005-10-24 06:35:18 +00006750 InsertNewInstBefore(NewCast, AI);
6751 AI.replaceAllUsesWith(NewCast);
6752 }
Chris Lattner216be912005-10-24 06:03:58 +00006753 return ReplaceInstUsesWith(CI, New);
6754}
6755
Chris Lattner1ebbe6a2006-05-13 02:06:03 +00006756/// CanEvaluateInDifferentType - Return true if we can take the specified value
Chris Lattnerda1d04a2007-03-03 05:27:34 +00006757/// and return it as type Ty without inserting any new casts and without
6758/// changing the computed value. This is used by code that tries to decide
6759/// whether promoting or shrinking integer operations to wider or smaller types
6760/// will allow us to eliminate a truncate or extend.
6761///
6762/// This is a truncation operation if Ty is smaller than V->getType(), or an
6763/// extension operation if Ty is larger.
6764static bool CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
Chris Lattner1ebbe6a2006-05-13 02:06:03 +00006765 int &NumCastsRemoved) {
Chris Lattnerda1d04a2007-03-03 05:27:34 +00006766 // We can always evaluate constants in another type.
6767 if (isa<ConstantInt>(V))
6768 return true;
Chris Lattner1ebbe6a2006-05-13 02:06:03 +00006769
6770 Instruction *I = dyn_cast<Instruction>(V);
Chris Lattnerda1d04a2007-03-03 05:27:34 +00006771 if (!I) return false;
6772
6773 const IntegerType *OrigTy = cast<IntegerType>(V->getType());
Chris Lattner1ebbe6a2006-05-13 02:06:03 +00006774
6775 switch (I->getOpcode()) {
Chris Lattnerda1d04a2007-03-03 05:27:34 +00006776 case Instruction::Add:
6777 case Instruction::Sub:
Chris Lattner1ebbe6a2006-05-13 02:06:03 +00006778 case Instruction::And:
6779 case Instruction::Or:
6780 case Instruction::Xor:
Chris Lattnerda1d04a2007-03-03 05:27:34 +00006781 if (!I->hasOneUse()) return false;
Chris Lattner1ebbe6a2006-05-13 02:06:03 +00006782 // These operators can all arbitrarily be extended or truncated.
6783 return CanEvaluateInDifferentType(I->getOperand(0), Ty, NumCastsRemoved) &&
6784 CanEvaluateInDifferentType(I->getOperand(1), Ty, NumCastsRemoved);
Chris Lattnerda1d04a2007-03-03 05:27:34 +00006785
Chris Lattner960acb02006-11-29 07:18:39 +00006786 case Instruction::Shl:
Chris Lattnerda1d04a2007-03-03 05:27:34 +00006787 if (!I->hasOneUse()) return false;
6788 // If we are truncating the result of this SHL, and if it's a shift of a
6789 // constant amount, we can always perform a SHL in a smaller type.
6790 if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
6791 if (Ty->getBitWidth() < OrigTy->getBitWidth() &&
6792 CI->getZExtValue() < Ty->getBitWidth())
6793 return CanEvaluateInDifferentType(I->getOperand(0), Ty,NumCastsRemoved);
6794 }
6795 break;
6796 case Instruction::LShr:
6797 if (!I->hasOneUse()) return false;
6798 // If this is a truncate of a logical shr, we can truncate it to a smaller
6799 // lshr iff we know that the bits we would otherwise be shifting in are
6800 // already zeros.
6801 if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
6802 if (Ty->getBitWidth() < OrigTy->getBitWidth() &&
6803 MaskedValueIsZero(I->getOperand(0),
6804 OrigTy->getBitMask() & ~Ty->getBitMask()) &&
6805 CI->getZExtValue() < Ty->getBitWidth()) {
6806 return CanEvaluateInDifferentType(I->getOperand(0), Ty, NumCastsRemoved);
6807 }
6808 }
Chris Lattner960acb02006-11-29 07:18:39 +00006809 break;
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006810 case Instruction::Trunc:
6811 case Instruction::ZExt:
6812 case Instruction::SExt:
Chris Lattner1ebbe6a2006-05-13 02:06:03 +00006813 // If this is a cast from the destination type, we can trivially eliminate
6814 // it, and this will remove a cast overall.
6815 if (I->getOperand(0)->getType() == Ty) {
Chris Lattner3fda3862006-06-28 17:34:50 +00006816 // If the first operand is itself a cast, and is eliminable, do not count
6817 // this as an eliminable cast. We would prefer to eliminate those two
6818 // casts first.
Reid Spencerde46e482006-11-02 20:25:50 +00006819 if (isa<CastInst>(I->getOperand(0)))
Chris Lattner3fda3862006-06-28 17:34:50 +00006820 return true;
6821
Chris Lattner1ebbe6a2006-05-13 02:06:03 +00006822 ++NumCastsRemoved;
6823 return true;
6824 }
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006825 break;
6826 default:
Chris Lattner1ebbe6a2006-05-13 02:06:03 +00006827 // TODO: Can handle more cases here.
6828 break;
6829 }
6830
6831 return false;
6832}
6833
6834/// EvaluateInDifferentType - Given an expression that
6835/// CanEvaluateInDifferentType returns true for, actually insert the code to
6836/// evaluate the expression.
Reid Spencer74a528b2006-12-13 18:21:21 +00006837Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty,
Chris Lattnerda1d04a2007-03-03 05:27:34 +00006838 bool isSigned) {
Chris Lattner1ebbe6a2006-05-13 02:06:03 +00006839 if (Constant *C = dyn_cast<Constant>(V))
Reid Spencer74a528b2006-12-13 18:21:21 +00006840 return ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/);
Chris Lattner1ebbe6a2006-05-13 02:06:03 +00006841
6842 // Otherwise, it must be an instruction.
6843 Instruction *I = cast<Instruction>(V);
Chris Lattnerd0622b62006-05-20 23:14:03 +00006844 Instruction *Res = 0;
Chris Lattner1ebbe6a2006-05-13 02:06:03 +00006845 switch (I->getOpcode()) {
Chris Lattnerda1d04a2007-03-03 05:27:34 +00006846 case Instruction::Add:
6847 case Instruction::Sub:
Chris Lattner1ebbe6a2006-05-13 02:06:03 +00006848 case Instruction::And:
6849 case Instruction::Or:
Chris Lattnerda1d04a2007-03-03 05:27:34 +00006850 case Instruction::Xor:
Chris Lattner960acb02006-11-29 07:18:39 +00006851 case Instruction::AShr:
6852 case Instruction::LShr:
6853 case Instruction::Shl: {
Reid Spencer74a528b2006-12-13 18:21:21 +00006854 Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned);
Chris Lattnerda1d04a2007-03-03 05:27:34 +00006855 Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
6856 Res = BinaryOperator::create((Instruction::BinaryOps)I->getOpcode(),
6857 LHS, RHS, I->getName());
Chris Lattner960acb02006-11-29 07:18:39 +00006858 break;
6859 }
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006860 case Instruction::Trunc:
6861 case Instruction::ZExt:
6862 case Instruction::SExt:
6863 case Instruction::BitCast:
6864 // If the source type of the cast is the type we're trying for then we can
6865 // just return the source. There's no need to insert it because its not new.
Chris Lattner1ebbe6a2006-05-13 02:06:03 +00006866 if (I->getOperand(0)->getType() == Ty)
6867 return I->getOperand(0);
6868
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006869 // Some other kind of cast, which shouldn't happen, so just ..
6870 // FALL THROUGH
6871 default:
Chris Lattner1ebbe6a2006-05-13 02:06:03 +00006872 // TODO: Can handle more cases here.
6873 assert(0 && "Unreachable!");
6874 break;
6875 }
6876
6877 return InsertNewInstBefore(Res, *I);
6878}
6879
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006880/// @brief Implement the transforms common to all CastInst visitors.
6881Instruction *InstCombiner::commonCastTransforms(CastInst &CI) {
Chris Lattner55d4bda2003-06-23 21:59:52 +00006882 Value *Src = CI.getOperand(0);
6883
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006884 // Casting undef to anything results in undef so might as just replace it and
6885 // get rid of the cast.
Chris Lattner81a7a232004-10-16 18:11:37 +00006886 if (isa<UndefValue>(Src)) // cast undef -> undef
6887 return ReplaceInstUsesWith(CI, UndefValue::get(CI.getType()));
6888
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006889 // Many cases of "cast of a cast" are eliminable. If its eliminable we just
6890 // eliminate it now.
Chris Lattner86102b82005-01-01 16:22:27 +00006891 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006892 if (Instruction::CastOps opc =
6893 isEliminableCastPair(CSrc, CI.getOpcode(), CI.getType(), TD)) {
6894 // The first cast (CSrc) is eliminable so we need to fix up or replace
6895 // the second cast (CI). CSrc will then have a good chance of being dead.
6896 return CastInst::create(opc, CSrc->getOperand(0), CI.getType());
Chris Lattner650b6da2002-08-02 20:00:25 +00006897 }
6898 }
Chris Lattner03841652004-05-25 04:29:21 +00006899
Chris Lattnerd0d51602003-06-21 23:12:02 +00006900 // If casting the result of a getelementptr instruction with no offset, turn
6901 // this into a cast of the original pointer!
6902 //
Chris Lattner55d4bda2003-06-23 21:59:52 +00006903 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
Chris Lattnerd0d51602003-06-21 23:12:02 +00006904 bool AllZeroOperands = true;
6905 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
6906 if (!isa<Constant>(GEP->getOperand(i)) ||
6907 !cast<Constant>(GEP->getOperand(i))->isNullValue()) {
6908 AllZeroOperands = false;
6909 break;
6910 }
6911 if (AllZeroOperands) {
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006912 // Changing the cast operand is usually not a good idea but it is safe
6913 // here because the pointer operand is being replaced with another
6914 // pointer operand so the opcode doesn't need to change.
Chris Lattnerd0d51602003-06-21 23:12:02 +00006915 CI.setOperand(0, GEP->getOperand(0));
6916 return &CI;
6917 }
6918 }
Chris Lattnerec45a4c2006-11-21 17:05:13 +00006919
Chris Lattnerf4ad1652003-11-02 05:57:39 +00006920 // If we are casting a malloc or alloca to a pointer to a type of the same
6921 // size, rewrite the allocation instruction to allocate the "right" type.
Chris Lattnerf4ad1652003-11-02 05:57:39 +00006922 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
Chris Lattner216be912005-10-24 06:03:58 +00006923 if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
6924 return V;
Chris Lattnerf4ad1652003-11-02 05:57:39 +00006925
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006926 // If we are casting a select then fold the cast into the select
Chris Lattner86102b82005-01-01 16:22:27 +00006927 if (SelectInst *SI = dyn_cast<SelectInst>(Src))
6928 if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
6929 return NV;
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006930
6931 // If we are casting a PHI then fold the cast into the PHI
Chris Lattner6a4adcd2004-09-29 05:07:12 +00006932 if (isa<PHINode>(Src))
6933 if (Instruction *NV = FoldOpIntoPhi(CI))
6934 return NV;
Chris Lattnerb19a5c62006-04-12 18:09:35 +00006935
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006936 return 0;
6937}
6938
Chris Lattnerda1d04a2007-03-03 05:27:34 +00006939/// Only the TRUNC, ZEXT, SEXT, and BITCAST can both operand and result as
6940/// integer types. This function implements the common transforms for all those
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006941/// cases.
6942/// @brief Implement the transforms common to CastInst with integer operands
6943Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) {
6944 if (Instruction *Result = commonCastTransforms(CI))
6945 return Result;
6946
6947 Value *Src = CI.getOperand(0);
6948 const Type *SrcTy = Src->getType();
6949 const Type *DestTy = CI.getType();
6950 unsigned SrcBitSize = SrcTy->getPrimitiveSizeInBits();
6951 unsigned DestBitSize = DestTy->getPrimitiveSizeInBits();
6952
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006953 // See if we can simplify any instructions used by the LHS whose sole
6954 // purpose is to compute bits we don't care about.
6955 uint64_t KnownZero = 0, KnownOne = 0;
Reid Spencera94d3942007-01-19 21:13:56 +00006956 if (SimplifyDemandedBits(&CI, cast<IntegerType>(DestTy)->getBitMask(),
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006957 KnownZero, KnownOne))
6958 return &CI;
6959
6960 // If the source isn't an instruction or has more than one use then we
6961 // can't do anything more.
Reid Spencer266e42b2006-12-23 06:05:41 +00006962 Instruction *SrcI = dyn_cast<Instruction>(Src);
6963 if (!SrcI || !Src->hasOneUse())
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006964 return 0;
6965
Chris Lattnerda1d04a2007-03-03 05:27:34 +00006966 // Attempt to propagate the cast into the instruction for int->int casts.
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006967 int NumCastsRemoved = 0;
Chris Lattnerda1d04a2007-03-03 05:27:34 +00006968 if (!isa<BitCastInst>(CI) &&
6969 CanEvaluateInDifferentType(SrcI, cast<IntegerType>(DestTy),
6970 NumCastsRemoved)) {
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006971 // If this cast is a truncate, evaluting in a different type always
6972 // eliminates the cast, so it is always a win. If this is a noop-cast
6973 // this just removes a noop cast which isn't pointful, but simplifies
6974 // the code. If this is a zero-extension, we need to do an AND to
6975 // maintain the clear top-part of the computation, so we require that
6976 // the input have eliminated at least one cast. If this is a sign
6977 // extension, we insert two new casts (to do the extension) so we
6978 // require that two casts have been eliminated.
Chris Lattnerda1d04a2007-03-03 05:27:34 +00006979 bool DoXForm;
6980 switch (CI.getOpcode()) {
6981 default:
6982 // All the others use floating point so we shouldn't actually
6983 // get here because of the check above.
6984 assert(0 && "Unknown cast type");
6985 case Instruction::Trunc:
6986 DoXForm = true;
6987 break;
6988 case Instruction::ZExt:
6989 DoXForm = NumCastsRemoved >= 1;
6990 break;
6991 case Instruction::SExt:
6992 DoXForm = NumCastsRemoved >= 2;
6993 break;
6994 case Instruction::BitCast:
6995 DoXForm = false;
6996 break;
Reid Spencer6c38f0b2006-11-27 01:05:10 +00006997 }
6998
6999 if (DoXForm) {
Reid Spencer74a528b2006-12-13 18:21:21 +00007000 Value *Res = EvaluateInDifferentType(SrcI, DestTy,
7001 CI.getOpcode() == Instruction::SExt);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007002 assert(Res->getType() == DestTy);
7003 switch (CI.getOpcode()) {
7004 default: assert(0 && "Unknown cast type!");
7005 case Instruction::Trunc:
7006 case Instruction::BitCast:
7007 // Just replace this cast with the result.
7008 return ReplaceInstUsesWith(CI, Res);
7009 case Instruction::ZExt: {
7010 // We need to emit an AND to clear the high bits.
7011 assert(SrcBitSize < DestBitSize && "Not a zext?");
7012 Constant *C =
Reid Spencerc635f472006-12-31 05:48:39 +00007013 ConstantInt::get(Type::Int64Ty, (1ULL << SrcBitSize)-1);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007014 if (DestBitSize < 64)
7015 C = ConstantExpr::getTrunc(C, DestTy);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007016 return BinaryOperator::createAnd(Res, C);
7017 }
7018 case Instruction::SExt:
7019 // We need to emit a cast to truncate, then a cast to sext.
7020 return CastInst::create(Instruction::SExt,
Reid Spencer13bc5d72006-12-12 09:18:51 +00007021 InsertCastBefore(Instruction::Trunc, Res, Src->getType(),
7022 CI), DestTy);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007023 }
7024 }
7025 }
7026
7027 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
7028 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
7029
7030 switch (SrcI->getOpcode()) {
7031 case Instruction::Add:
7032 case Instruction::Mul:
7033 case Instruction::And:
7034 case Instruction::Or:
7035 case Instruction::Xor:
7036 // If we are discarding information, or just changing the sign,
7037 // rewrite.
7038 if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
7039 // Don't insert two casts if they cannot be eliminated. We allow
7040 // two casts to be inserted if the sizes are the same. This could
7041 // only be converting signedness, which is a noop.
7042 if (DestBitSize == SrcBitSize ||
Reid Spencer266e42b2006-12-23 06:05:41 +00007043 !ValueRequiresCast(CI.getOpcode(), Op1, DestTy,TD) ||
7044 !ValueRequiresCast(CI.getOpcode(), Op0, DestTy, TD)) {
Reid Spencer2a499b02006-12-13 17:19:09 +00007045 Instruction::CastOps opcode = CI.getOpcode();
Reid Spencer13bc5d72006-12-12 09:18:51 +00007046 Value *Op0c = InsertOperandCastBefore(opcode, Op0, DestTy, SrcI);
7047 Value *Op1c = InsertOperandCastBefore(opcode, Op1, DestTy, SrcI);
7048 return BinaryOperator::create(
7049 cast<BinaryOperator>(SrcI)->getOpcode(), Op0c, Op1c);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007050 }
7051 }
7052
7053 // cast (xor bool X, true) to int --> xor (cast bool X to int), 1
7054 if (isa<ZExtInst>(CI) && SrcBitSize == 1 &&
7055 SrcI->getOpcode() == Instruction::Xor &&
Zhou Sheng75b871f2007-01-11 12:24:14 +00007056 Op1 == ConstantInt::getTrue() &&
Reid Spencer266e42b2006-12-23 06:05:41 +00007057 (!Op0->hasOneUse() || !isa<CmpInst>(Op0))) {
Reid Spencer13bc5d72006-12-12 09:18:51 +00007058 Value *New = InsertOperandCastBefore(Instruction::ZExt, Op0, DestTy, &CI);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007059 return BinaryOperator::createXor(New, ConstantInt::get(CI.getType(), 1));
7060 }
7061 break;
7062 case Instruction::SDiv:
7063 case Instruction::UDiv:
7064 case Instruction::SRem:
7065 case Instruction::URem:
7066 // If we are just changing the sign, rewrite.
7067 if (DestBitSize == SrcBitSize) {
7068 // Don't insert two casts if they cannot be eliminated. We allow
7069 // two casts to be inserted if the sizes are the same. This could
7070 // only be converting signedness, which is a noop.
Reid Spencer266e42b2006-12-23 06:05:41 +00007071 if (!ValueRequiresCast(CI.getOpcode(), Op1, DestTy, TD) ||
7072 !ValueRequiresCast(CI.getOpcode(), Op0, DestTy, TD)) {
Reid Spencer13bc5d72006-12-12 09:18:51 +00007073 Value *Op0c = InsertOperandCastBefore(Instruction::BitCast,
7074 Op0, DestTy, SrcI);
7075 Value *Op1c = InsertOperandCastBefore(Instruction::BitCast,
7076 Op1, DestTy, SrcI);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007077 return BinaryOperator::create(
7078 cast<BinaryOperator>(SrcI)->getOpcode(), Op0c, Op1c);
7079 }
7080 }
7081 break;
7082
7083 case Instruction::Shl:
7084 // Allow changing the sign of the source operand. Do not allow
7085 // changing the size of the shift, UNLESS the shift amount is a
7086 // constant. We must not change variable sized shifts to a smaller
7087 // size, because it is undefined to shift more bits out than exist
7088 // in the value.
7089 if (DestBitSize == SrcBitSize ||
7090 (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
Reid Spencer13bc5d72006-12-12 09:18:51 +00007091 Instruction::CastOps opcode = (DestBitSize == SrcBitSize ?
7092 Instruction::BitCast : Instruction::Trunc);
7093 Value *Op0c = InsertOperandCastBefore(opcode, Op0, DestTy, SrcI);
Reid Spencer2341c222007-02-02 02:16:23 +00007094 Value *Op1c = InsertOperandCastBefore(opcode, Op1, DestTy, SrcI);
Reid Spencer0d5f9232007-02-02 14:08:20 +00007095 return BinaryOperator::createShl(Op0c, Op1c);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007096 }
7097 break;
7098 case Instruction::AShr:
7099 // If this is a signed shr, and if all bits shifted in are about to be
7100 // truncated off, turn it into an unsigned shr to allow greater
7101 // simplifications.
7102 if (DestBitSize < SrcBitSize &&
7103 isa<ConstantInt>(Op1)) {
7104 unsigned ShiftAmt = cast<ConstantInt>(Op1)->getZExtValue();
7105 if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) {
7106 // Insert the new logical shift right.
Reid Spencer0d5f9232007-02-02 14:08:20 +00007107 return BinaryOperator::createLShr(Op0, Op1);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007108 }
7109 }
7110 break;
7111
Reid Spencer266e42b2006-12-23 06:05:41 +00007112 case Instruction::ICmp:
7113 // If we are just checking for a icmp eq of a single bit and casting it
7114 // to an integer, then shift the bit to the appropriate place and then
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007115 // cast to integer to avoid the comparison.
7116 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
7117 uint64_t Op1CV = Op1C->getZExtValue();
7118 // cast (X == 0) to int --> X^1 iff X has only the low bit set.
7119 // cast (X == 0) to int --> (X>>1)^1 iff X has only the 2nd bit set.
7120 // cast (X == 1) to int --> X iff X has only the low bit set.
7121 // cast (X == 2) to int --> X>>1 iff X has only the 2nd bit set.
7122 // cast (X != 0) to int --> X iff X has only the low bit set.
7123 // cast (X != 0) to int --> X>>1 iff X has only the 2nd bit set.
7124 // cast (X != 1) to int --> X^1 iff X has only the low bit set.
7125 // cast (X != 2) to int --> (X>>1)^1 iff X has only the 2nd bit set.
7126 if (Op1CV == 0 || isPowerOf2_64(Op1CV)) {
7127 // If Op1C some other power of two, convert:
7128 uint64_t KnownZero, KnownOne;
Reid Spencera94d3942007-01-19 21:13:56 +00007129 uint64_t TypeMask = Op1C->getType()->getBitMask();
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007130 ComputeMaskedBits(Op0, TypeMask, KnownZero, KnownOne);
Reid Spencer266e42b2006-12-23 06:05:41 +00007131
7132 // This only works for EQ and NE
7133 ICmpInst::Predicate pred = cast<ICmpInst>(SrcI)->getPredicate();
7134 if (pred != ICmpInst::ICMP_NE && pred != ICmpInst::ICMP_EQ)
7135 break;
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007136
7137 if (isPowerOf2_64(KnownZero^TypeMask)) { // Exactly 1 possible 1?
Reid Spencer266e42b2006-12-23 06:05:41 +00007138 bool isNE = pred == ICmpInst::ICMP_NE;
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007139 if (Op1CV && (Op1CV != (KnownZero^TypeMask))) {
7140 // (X&4) == 2 --> false
7141 // (X&4) != 2 --> true
Reid Spencercddc9df2007-01-12 04:24:46 +00007142 Constant *Res = ConstantInt::get(Type::Int1Ty, isNE);
Reid Spencerbb65ebf2006-12-12 23:36:14 +00007143 Res = ConstantExpr::getZExt(Res, CI.getType());
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007144 return ReplaceInstUsesWith(CI, Res);
7145 }
7146
7147 unsigned ShiftAmt = Log2_64(KnownZero^TypeMask);
7148 Value *In = Op0;
7149 if (ShiftAmt) {
7150 // Perform a logical shr by shiftamt.
7151 // Insert the shift to put the result in the low bit.
7152 In = InsertNewInstBefore(
Reid Spencer0d5f9232007-02-02 14:08:20 +00007153 BinaryOperator::createLShr(In,
Reid Spencer2341c222007-02-02 02:16:23 +00007154 ConstantInt::get(In->getType(), ShiftAmt),
7155 In->getName()+".lobit"), CI);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007156 }
7157
Reid Spencer266e42b2006-12-23 06:05:41 +00007158 if ((Op1CV != 0) == isNE) { // Toggle the low bit.
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007159 Constant *One = ConstantInt::get(In->getType(), 1);
7160 In = BinaryOperator::createXor(In, One, "tmp");
7161 InsertNewInstBefore(cast<Instruction>(In), CI);
7162 }
7163
7164 if (CI.getType() == In->getType())
7165 return ReplaceInstUsesWith(CI, In);
7166 else
Reid Spencerbb65ebf2006-12-12 23:36:14 +00007167 return CastInst::createIntegerCast(In, CI.getType(), false/*ZExt*/);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007168 }
7169 }
7170 }
7171 break;
7172 }
7173 return 0;
7174}
7175
7176Instruction *InstCombiner::visitTrunc(CastInst &CI) {
Chris Lattnerd747f012006-11-29 07:04:07 +00007177 if (Instruction *Result = commonIntCastTransforms(CI))
7178 return Result;
7179
7180 Value *Src = CI.getOperand(0);
7181 const Type *Ty = CI.getType();
7182 unsigned DestBitWidth = Ty->getPrimitiveSizeInBits();
7183
7184 if (Instruction *SrcI = dyn_cast<Instruction>(Src)) {
7185 switch (SrcI->getOpcode()) {
7186 default: break;
7187 case Instruction::LShr:
7188 // We can shrink lshr to something smaller if we know the bits shifted in
7189 // are already zeros.
7190 if (ConstantInt *ShAmtV = dyn_cast<ConstantInt>(SrcI->getOperand(1))) {
7191 unsigned ShAmt = ShAmtV->getZExtValue();
7192
7193 // Get a mask for the bits shifting in.
7194 uint64_t Mask = (~0ULL >> (64-ShAmt)) << DestBitWidth;
Reid Spencer13bc5d72006-12-12 09:18:51 +00007195 Value* SrcIOp0 = SrcI->getOperand(0);
7196 if (SrcI->hasOneUse() && MaskedValueIsZero(SrcIOp0, Mask)) {
Chris Lattnerd747f012006-11-29 07:04:07 +00007197 if (ShAmt >= DestBitWidth) // All zeros.
7198 return ReplaceInstUsesWith(CI, Constant::getNullValue(Ty));
7199
7200 // Okay, we can shrink this. Truncate the input, then return a new
7201 // shift.
Reid Spencer2341c222007-02-02 02:16:23 +00007202 Value *V1 = InsertCastBefore(Instruction::Trunc, SrcIOp0, Ty, CI);
7203 Value *V2 = InsertCastBefore(Instruction::Trunc, SrcI->getOperand(1),
7204 Ty, CI);
Reid Spencer0d5f9232007-02-02 14:08:20 +00007205 return BinaryOperator::createLShr(V1, V2);
Chris Lattnerd747f012006-11-29 07:04:07 +00007206 }
Chris Lattnerc209b582006-12-05 01:26:29 +00007207 } else { // This is a variable shr.
7208
7209 // Turn 'trunc (lshr X, Y) to bool' into '(X & (1 << Y)) != 0'. This is
7210 // more LLVM instructions, but allows '1 << Y' to be hoisted if
7211 // loop-invariant and CSE'd.
Reid Spencer542964f2007-01-11 18:21:29 +00007212 if (CI.getType() == Type::Int1Ty && SrcI->hasOneUse()) {
Chris Lattnerc209b582006-12-05 01:26:29 +00007213 Value *One = ConstantInt::get(SrcI->getType(), 1);
7214
Reid Spencer2341c222007-02-02 02:16:23 +00007215 Value *V = InsertNewInstBefore(
Reid Spencer0d5f9232007-02-02 14:08:20 +00007216 BinaryOperator::createShl(One, SrcI->getOperand(1),
Reid Spencer2341c222007-02-02 02:16:23 +00007217 "tmp"), CI);
Chris Lattnerc209b582006-12-05 01:26:29 +00007218 V = InsertNewInstBefore(BinaryOperator::createAnd(V,
7219 SrcI->getOperand(0),
7220 "tmp"), CI);
7221 Value *Zero = Constant::getNullValue(V->getType());
Reid Spencer266e42b2006-12-23 06:05:41 +00007222 return new ICmpInst(ICmpInst::ICMP_NE, V, Zero);
Chris Lattnerc209b582006-12-05 01:26:29 +00007223 }
Chris Lattnerd747f012006-11-29 07:04:07 +00007224 }
7225 break;
7226 }
7227 }
7228
7229 return 0;
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007230}
7231
7232Instruction *InstCombiner::visitZExt(CastInst &CI) {
7233 // If one of the common conversion will work ..
7234 if (Instruction *Result = commonIntCastTransforms(CI))
7235 return Result;
7236
7237 Value *Src = CI.getOperand(0);
7238
7239 // If this is a cast of a cast
7240 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007241 // If this is a TRUNC followed by a ZEXT then we are dealing with integral
7242 // types and if the sizes are just right we can convert this into a logical
7243 // 'and' which will be much cheaper than the pair of casts.
7244 if (isa<TruncInst>(CSrc)) {
7245 // Get the sizes of the types involved
7246 Value *A = CSrc->getOperand(0);
7247 unsigned SrcSize = A->getType()->getPrimitiveSizeInBits();
7248 unsigned MidSize = CSrc->getType()->getPrimitiveSizeInBits();
7249 unsigned DstSize = CI.getType()->getPrimitiveSizeInBits();
7250 // If we're actually extending zero bits and the trunc is a no-op
7251 if (MidSize < DstSize && SrcSize == DstSize) {
7252 // Replace both of the casts with an And of the type mask.
Reid Spencera94d3942007-01-19 21:13:56 +00007253 uint64_t AndValue = cast<IntegerType>(CSrc->getType())->getBitMask();
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007254 Constant *AndConst = ConstantInt::get(A->getType(), AndValue);
7255 Instruction *And =
7256 BinaryOperator::createAnd(CSrc->getOperand(0), AndConst);
7257 // Unfortunately, if the type changed, we need to cast it back.
7258 if (And->getType() != CI.getType()) {
7259 And->setName(CSrc->getName()+".mask");
7260 InsertNewInstBefore(And, CI);
Reid Spencerbb65ebf2006-12-12 23:36:14 +00007261 And = CastInst::createIntegerCast(And, CI.getType(), false/*ZExt*/);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007262 }
7263 return And;
7264 }
7265 }
7266 }
7267
7268 return 0;
7269}
7270
7271Instruction *InstCombiner::visitSExt(CastInst &CI) {
7272 return commonIntCastTransforms(CI);
7273}
7274
7275Instruction *InstCombiner::visitFPTrunc(CastInst &CI) {
7276 return commonCastTransforms(CI);
7277}
7278
7279Instruction *InstCombiner::visitFPExt(CastInst &CI) {
7280 return commonCastTransforms(CI);
7281}
7282
7283Instruction *InstCombiner::visitFPToUI(CastInst &CI) {
Reid Spencerad05ee92006-11-30 23:13:36 +00007284 return commonCastTransforms(CI);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007285}
7286
7287Instruction *InstCombiner::visitFPToSI(CastInst &CI) {
Reid Spencerad05ee92006-11-30 23:13:36 +00007288 return commonCastTransforms(CI);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007289}
7290
7291Instruction *InstCombiner::visitUIToFP(CastInst &CI) {
7292 return commonCastTransforms(CI);
7293}
7294
7295Instruction *InstCombiner::visitSIToFP(CastInst &CI) {
7296 return commonCastTransforms(CI);
7297}
7298
7299Instruction *InstCombiner::visitPtrToInt(CastInst &CI) {
Reid Spencerad05ee92006-11-30 23:13:36 +00007300 return commonCastTransforms(CI);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007301}
7302
7303Instruction *InstCombiner::visitIntToPtr(CastInst &CI) {
7304 return commonCastTransforms(CI);
7305}
7306
7307Instruction *InstCombiner::visitBitCast(CastInst &CI) {
7308
7309 // If the operands are integer typed then apply the integer transforms,
7310 // otherwise just apply the common ones.
7311 Value *Src = CI.getOperand(0);
7312 const Type *SrcTy = Src->getType();
7313 const Type *DestTy = CI.getType();
7314
Chris Lattner03c49532007-01-15 02:27:26 +00007315 if (SrcTy->isInteger() && DestTy->isInteger()) {
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007316 if (Instruction *Result = commonIntCastTransforms(CI))
7317 return Result;
7318 } else {
7319 if (Instruction *Result = commonCastTransforms(CI))
7320 return Result;
7321 }
7322
7323
7324 // Get rid of casts from one type to the same type. These are useless and can
7325 // be replaced by the operand.
7326 if (DestTy == Src->getType())
7327 return ReplaceInstUsesWith(CI, Src);
7328
Chris Lattnerb19a5c62006-04-12 18:09:35 +00007329 // If the source and destination are pointers, and this cast is equivalent to
7330 // a getelementptr X, 0, 0, 0... turn it into the appropriate getelementptr.
7331 // This can enhance SROA and other transforms that want type-safe pointers.
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007332 if (const PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) {
7333 if (const PointerType *SrcPTy = dyn_cast<PointerType>(SrcTy)) {
7334 const Type *DstElTy = DstPTy->getElementType();
7335 const Type *SrcElTy = SrcPTy->getElementType();
Chris Lattnerb19a5c62006-04-12 18:09:35 +00007336
Reid Spencerc635f472006-12-31 05:48:39 +00007337 Constant *ZeroUInt = Constant::getNullValue(Type::Int32Ty);
Chris Lattnerb19a5c62006-04-12 18:09:35 +00007338 unsigned NumZeros = 0;
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007339 while (SrcElTy != DstElTy &&
7340 isa<CompositeType>(SrcElTy) && !isa<PointerType>(SrcElTy) &&
7341 SrcElTy->getNumContainedTypes() /* not "{}" */) {
7342 SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(ZeroUInt);
Chris Lattnerb19a5c62006-04-12 18:09:35 +00007343 ++NumZeros;
7344 }
Chris Lattner6a4adcd2004-09-29 05:07:12 +00007345
Chris Lattnerb19a5c62006-04-12 18:09:35 +00007346 // If we found a path from the src to dest, create the getelementptr now.
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007347 if (SrcElTy == DstElTy) {
Chris Lattner416a8932007-01-31 20:08:52 +00007348 SmallVector<Value*, 8> Idxs(NumZeros+1, ZeroUInt);
7349 return new GetElementPtrInst(Src, &Idxs[0], Idxs.size());
Chris Lattnerb19a5c62006-04-12 18:09:35 +00007350 }
7351 }
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007352 }
Chris Lattnerdfae8be2003-07-24 17:35:25 +00007353
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007354 if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) {
7355 if (SVI->hasOneUse()) {
7356 // Okay, we have (bitconvert (shuffle ..)). Check to see if this is
7357 // a bitconvert to a vector with the same # elts.
Reid Spencerd84d35b2007-02-15 02:26:10 +00007358 if (isa<VectorType>(DestTy) &&
7359 cast<VectorType>(DestTy)->getNumElements() ==
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007360 SVI->getType()->getNumElements()) {
7361 CastInst *Tmp;
7362 // If either of the operands is a cast from CI.getType(), then
7363 // evaluating the shuffle in the casted destination's type will allow
7364 // us to eliminate at least one cast.
7365 if (((Tmp = dyn_cast<CastInst>(SVI->getOperand(0))) &&
7366 Tmp->getOperand(0)->getType() == DestTy) ||
7367 ((Tmp = dyn_cast<CastInst>(SVI->getOperand(1))) &&
7368 Tmp->getOperand(0)->getType() == DestTy)) {
Reid Spencer13bc5d72006-12-12 09:18:51 +00007369 Value *LHS = InsertOperandCastBefore(Instruction::BitCast,
7370 SVI->getOperand(0), DestTy, &CI);
7371 Value *RHS = InsertOperandCastBefore(Instruction::BitCast,
7372 SVI->getOperand(1), DestTy, &CI);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007373 // Return a new shuffle vector. Use the same element ID's, as we
7374 // know the vector types match #elts.
7375 return new ShuffleVectorInst(LHS, RHS, SVI->getOperand(2));
Chris Lattner99155be2006-05-25 23:24:33 +00007376 }
7377 }
7378 }
7379 }
Chris Lattner260ab202002-04-18 17:39:14 +00007380 return 0;
Chris Lattnerca081252001-12-14 16:52:21 +00007381}
7382
Chris Lattner56e4d3d2004-04-09 23:46:01 +00007383/// GetSelectFoldableOperands - We want to turn code that looks like this:
7384/// %C = or %A, %B
7385/// %D = select %cond, %C, %A
7386/// into:
7387/// %C = select %cond, %B, 0
7388/// %D = or %A, %C
7389///
7390/// Assuming that the specified instruction is an operand to the select, return
7391/// a bitmask indicating which operands of this instruction are foldable if they
7392/// equal the other incoming value of the select.
7393///
7394static unsigned GetSelectFoldableOperands(Instruction *I) {
7395 switch (I->getOpcode()) {
7396 case Instruction::Add:
7397 case Instruction::Mul:
7398 case Instruction::And:
7399 case Instruction::Or:
7400 case Instruction::Xor:
7401 return 3; // Can fold through either operand.
7402 case Instruction::Sub: // Can only fold on the amount subtracted.
7403 case Instruction::Shl: // Can only fold on the shift amount.
Reid Spencerfdff9382006-11-08 06:47:33 +00007404 case Instruction::LShr:
7405 case Instruction::AShr:
Misha Brukmanb1c93172005-04-21 23:48:37 +00007406 return 1;
Chris Lattner56e4d3d2004-04-09 23:46:01 +00007407 default:
7408 return 0; // Cannot fold
7409 }
7410}
7411
7412/// GetSelectFoldableConstant - For the same transformation as the previous
7413/// function, return the identity constant that goes into the select.
7414static Constant *GetSelectFoldableConstant(Instruction *I) {
7415 switch (I->getOpcode()) {
7416 default: assert(0 && "This cannot happen!"); abort();
7417 case Instruction::Add:
7418 case Instruction::Sub:
7419 case Instruction::Or:
7420 case Instruction::Xor:
Chris Lattner56e4d3d2004-04-09 23:46:01 +00007421 case Instruction::Shl:
Reid Spencerfdff9382006-11-08 06:47:33 +00007422 case Instruction::LShr:
7423 case Instruction::AShr:
Reid Spencer2341c222007-02-02 02:16:23 +00007424 return Constant::getNullValue(I->getType());
Chris Lattner56e4d3d2004-04-09 23:46:01 +00007425 case Instruction::And:
7426 return ConstantInt::getAllOnesValue(I->getType());
7427 case Instruction::Mul:
7428 return ConstantInt::get(I->getType(), 1);
7429 }
7430}
7431
Chris Lattner411336f2005-01-19 21:50:18 +00007432/// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
7433/// have the same opcode and only one use each. Try to simplify this.
7434Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
7435 Instruction *FI) {
7436 if (TI->getNumOperands() == 1) {
7437 // If this is a non-volatile load or a cast from the same type,
7438 // merge.
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007439 if (TI->isCast()) {
Chris Lattner411336f2005-01-19 21:50:18 +00007440 if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
7441 return 0;
7442 } else {
7443 return 0; // unknown unary op.
7444 }
Misha Brukmanb1c93172005-04-21 23:48:37 +00007445
Chris Lattner411336f2005-01-19 21:50:18 +00007446 // Fold this by inserting a select from the input values.
7447 SelectInst *NewSI = new SelectInst(SI.getCondition(), TI->getOperand(0),
7448 FI->getOperand(0), SI.getName()+".v");
7449 InsertNewInstBefore(NewSI, SI);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007450 return CastInst::create(Instruction::CastOps(TI->getOpcode()), NewSI,
7451 TI->getType());
Chris Lattner411336f2005-01-19 21:50:18 +00007452 }
7453
Reid Spencer2341c222007-02-02 02:16:23 +00007454 // Only handle binary operators here.
7455 if (!isa<BinaryOperator>(TI))
Chris Lattner411336f2005-01-19 21:50:18 +00007456 return 0;
7457
7458 // Figure out if the operations have any operands in common.
7459 Value *MatchOp, *OtherOpT, *OtherOpF;
7460 bool MatchIsOpZero;
7461 if (TI->getOperand(0) == FI->getOperand(0)) {
7462 MatchOp = TI->getOperand(0);
7463 OtherOpT = TI->getOperand(1);
7464 OtherOpF = FI->getOperand(1);
7465 MatchIsOpZero = true;
7466 } else if (TI->getOperand(1) == FI->getOperand(1)) {
7467 MatchOp = TI->getOperand(1);
7468 OtherOpT = TI->getOperand(0);
7469 OtherOpF = FI->getOperand(0);
7470 MatchIsOpZero = false;
7471 } else if (!TI->isCommutative()) {
7472 return 0;
7473 } else if (TI->getOperand(0) == FI->getOperand(1)) {
7474 MatchOp = TI->getOperand(0);
7475 OtherOpT = TI->getOperand(1);
7476 OtherOpF = FI->getOperand(0);
7477 MatchIsOpZero = true;
7478 } else if (TI->getOperand(1) == FI->getOperand(0)) {
7479 MatchOp = TI->getOperand(1);
7480 OtherOpT = TI->getOperand(0);
7481 OtherOpF = FI->getOperand(1);
7482 MatchIsOpZero = true;
7483 } else {
7484 return 0;
7485 }
7486
7487 // If we reach here, they do have operations in common.
7488 SelectInst *NewSI = new SelectInst(SI.getCondition(), OtherOpT,
7489 OtherOpF, SI.getName()+".v");
7490 InsertNewInstBefore(NewSI, SI);
7491
7492 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
7493 if (MatchIsOpZero)
7494 return BinaryOperator::create(BO->getOpcode(), MatchOp, NewSI);
7495 else
7496 return BinaryOperator::create(BO->getOpcode(), NewSI, MatchOp);
Chris Lattner411336f2005-01-19 21:50:18 +00007497 }
Reid Spencer2f34b982007-02-02 14:41:37 +00007498 assert(0 && "Shouldn't get here");
7499 return 0;
Chris Lattner411336f2005-01-19 21:50:18 +00007500}
7501
Chris Lattnerb909e8b2004-03-12 05:52:32 +00007502Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
Chris Lattner533bc492004-03-30 19:37:13 +00007503 Value *CondVal = SI.getCondition();
7504 Value *TrueVal = SI.getTrueValue();
7505 Value *FalseVal = SI.getFalseValue();
7506
7507 // select true, X, Y -> X
7508 // select false, X, Y -> Y
Zhou Sheng75b871f2007-01-11 12:24:14 +00007509 if (ConstantInt *C = dyn_cast<ConstantInt>(CondVal))
Reid Spencercddc9df2007-01-12 04:24:46 +00007510 return ReplaceInstUsesWith(SI, C->getZExtValue() ? TrueVal : FalseVal);
Chris Lattner533bc492004-03-30 19:37:13 +00007511
7512 // select C, X, X -> X
7513 if (TrueVal == FalseVal)
7514 return ReplaceInstUsesWith(SI, TrueVal);
7515
Chris Lattner81a7a232004-10-16 18:11:37 +00007516 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
7517 return ReplaceInstUsesWith(SI, FalseVal);
7518 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
7519 return ReplaceInstUsesWith(SI, TrueVal);
7520 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
7521 if (isa<Constant>(TrueVal))
7522 return ReplaceInstUsesWith(SI, TrueVal);
7523 else
7524 return ReplaceInstUsesWith(SI, FalseVal);
7525 }
7526
Reid Spencer542964f2007-01-11 18:21:29 +00007527 if (SI.getType() == Type::Int1Ty) {
Reid Spencer7a9c62b2007-01-12 07:05:14 +00007528 if (ConstantInt *C = dyn_cast<ConstantInt>(TrueVal)) {
Reid Spencercddc9df2007-01-12 04:24:46 +00007529 if (C->getZExtValue()) {
Chris Lattner1c631e82004-04-08 04:43:23 +00007530 // Change: A = select B, true, C --> A = or B, C
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00007531 return BinaryOperator::createOr(CondVal, FalseVal);
Chris Lattner1c631e82004-04-08 04:43:23 +00007532 } else {
7533 // Change: A = select B, false, C --> A = and !B, C
7534 Value *NotCond =
7535 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
7536 "not."+CondVal->getName()), SI);
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00007537 return BinaryOperator::createAnd(NotCond, FalseVal);
Chris Lattner1c631e82004-04-08 04:43:23 +00007538 }
Reid Spencer7a9c62b2007-01-12 07:05:14 +00007539 } else if (ConstantInt *C = dyn_cast<ConstantInt>(FalseVal)) {
Reid Spencercddc9df2007-01-12 04:24:46 +00007540 if (C->getZExtValue() == false) {
Chris Lattner1c631e82004-04-08 04:43:23 +00007541 // Change: A = select B, C, false --> A = and B, C
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00007542 return BinaryOperator::createAnd(CondVal, TrueVal);
Chris Lattner1c631e82004-04-08 04:43:23 +00007543 } else {
7544 // Change: A = select B, C, true --> A = or !B, C
7545 Value *NotCond =
7546 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
7547 "not."+CondVal->getName()), SI);
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00007548 return BinaryOperator::createOr(NotCond, TrueVal);
Chris Lattner1c631e82004-04-08 04:43:23 +00007549 }
7550 }
Zhou Sheng75b871f2007-01-11 12:24:14 +00007551 }
Chris Lattner1c631e82004-04-08 04:43:23 +00007552
Chris Lattner183b3362004-04-09 19:05:30 +00007553 // Selecting between two integer constants?
7554 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
7555 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
7556 // select C, 1, 0 -> cast C to int
Reid Spencere0fc4df2006-10-20 07:07:24 +00007557 if (FalseValC->isNullValue() && TrueValC->getZExtValue() == 1) {
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007558 return CastInst::create(Instruction::ZExt, CondVal, SI.getType());
Reid Spencere0fc4df2006-10-20 07:07:24 +00007559 } else if (TrueValC->isNullValue() && FalseValC->getZExtValue() == 1) {
Chris Lattner183b3362004-04-09 19:05:30 +00007560 // select C, 0, 1 -> cast !C to int
7561 Value *NotCond =
7562 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
Chris Lattnercf7baf32004-04-09 18:19:44 +00007563 "not."+CondVal->getName()), SI);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007564 return CastInst::create(Instruction::ZExt, NotCond, SI.getType());
Chris Lattnercf7baf32004-04-09 18:19:44 +00007565 }
Chris Lattner35167c32004-06-09 07:59:58 +00007566
Reid Spencer266e42b2006-12-23 06:05:41 +00007567 if (ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition())) {
Chris Lattner380c7e92006-09-20 04:44:59 +00007568
Reid Spencer266e42b2006-12-23 06:05:41 +00007569 // (x <s 0) ? -1 : 0 -> ashr x, 31
7570 // (x >u 2147483647) ? -1 : 0 -> ashr x, 31
Chris Lattner380c7e92006-09-20 04:44:59 +00007571 if (TrueValC->isAllOnesValue() && FalseValC->isNullValue())
7572 if (ConstantInt *CmpCst = dyn_cast<ConstantInt>(IC->getOperand(1))) {
7573 bool CanXForm = false;
Reid Spencer266e42b2006-12-23 06:05:41 +00007574 if (IC->isSignedPredicate())
Chris Lattner380c7e92006-09-20 04:44:59 +00007575 CanXForm = CmpCst->isNullValue() &&
Reid Spencer266e42b2006-12-23 06:05:41 +00007576 IC->getPredicate() == ICmpInst::ICMP_SLT;
Chris Lattner380c7e92006-09-20 04:44:59 +00007577 else {
7578 unsigned Bits = CmpCst->getType()->getPrimitiveSizeInBits();
Reid Spencere0fc4df2006-10-20 07:07:24 +00007579 CanXForm = (CmpCst->getZExtValue() == ~0ULL >> (64-Bits+1)) &&
Reid Spencer266e42b2006-12-23 06:05:41 +00007580 IC->getPredicate() == ICmpInst::ICMP_UGT;
Chris Lattner380c7e92006-09-20 04:44:59 +00007581 }
7582
7583 if (CanXForm) {
7584 // The comparison constant and the result are not neccessarily the
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007585 // same width. Make an all-ones value by inserting a AShr.
Chris Lattner380c7e92006-09-20 04:44:59 +00007586 Value *X = IC->getOperand(0);
Chris Lattner380c7e92006-09-20 04:44:59 +00007587 unsigned Bits = X->getType()->getPrimitiveSizeInBits();
Reid Spencer2341c222007-02-02 02:16:23 +00007588 Constant *ShAmt = ConstantInt::get(X->getType(), Bits-1);
7589 Instruction *SRA = BinaryOperator::create(Instruction::AShr, X,
7590 ShAmt, "ones");
Chris Lattner380c7e92006-09-20 04:44:59 +00007591 InsertNewInstBefore(SRA, SI);
7592
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007593 // Finally, convert to the type of the select RHS. We figure out
7594 // if this requires a SExt, Trunc or BitCast based on the sizes.
7595 Instruction::CastOps opc = Instruction::BitCast;
7596 unsigned SRASize = SRA->getType()->getPrimitiveSizeInBits();
7597 unsigned SISize = SI.getType()->getPrimitiveSizeInBits();
7598 if (SRASize < SISize)
7599 opc = Instruction::SExt;
7600 else if (SRASize > SISize)
7601 opc = Instruction::Trunc;
7602 return CastInst::create(opc, SRA, SI.getType());
Chris Lattner380c7e92006-09-20 04:44:59 +00007603 }
7604 }
7605
7606
7607 // If one of the constants is zero (we know they can't both be) and we
Reid Spencer266e42b2006-12-23 06:05:41 +00007608 // have a fcmp instruction with zero, and we have an 'and' with the
Chris Lattner380c7e92006-09-20 04:44:59 +00007609 // non-constant value, eliminate this whole mess. This corresponds to
7610 // cases like this: ((X & 27) ? 27 : 0)
7611 if (TrueValC->isNullValue() || FalseValC->isNullValue())
Chris Lattnerb3f24c92006-09-18 04:22:48 +00007612 if (IC->isEquality() && isa<ConstantInt>(IC->getOperand(1)) &&
Chris Lattner35167c32004-06-09 07:59:58 +00007613 cast<Constant>(IC->getOperand(1))->isNullValue())
7614 if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
7615 if (ICA->getOpcode() == Instruction::And &&
Misha Brukmanb1c93172005-04-21 23:48:37 +00007616 isa<ConstantInt>(ICA->getOperand(1)) &&
7617 (ICA->getOperand(1) == TrueValC ||
7618 ICA->getOperand(1) == FalseValC) &&
Chris Lattner35167c32004-06-09 07:59:58 +00007619 isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
7620 // Okay, now we know that everything is set up, we just don't
Reid Spencer266e42b2006-12-23 06:05:41 +00007621 // know whether we have a icmp_ne or icmp_eq and whether the
7622 // true or false val is the zero.
Chris Lattner35167c32004-06-09 07:59:58 +00007623 bool ShouldNotVal = !TrueValC->isNullValue();
Reid Spencer266e42b2006-12-23 06:05:41 +00007624 ShouldNotVal ^= IC->getPredicate() == ICmpInst::ICMP_NE;
Chris Lattner35167c32004-06-09 07:59:58 +00007625 Value *V = ICA;
7626 if (ShouldNotVal)
7627 V = InsertNewInstBefore(BinaryOperator::create(
7628 Instruction::Xor, V, ICA->getOperand(1)), SI);
7629 return ReplaceInstUsesWith(SI, V);
7630 }
Chris Lattner380c7e92006-09-20 04:44:59 +00007631 }
Chris Lattner533bc492004-03-30 19:37:13 +00007632 }
Chris Lattner623fba12004-04-10 22:21:27 +00007633
7634 // See if we are selecting two values based on a comparison of the two values.
Reid Spencer266e42b2006-12-23 06:05:41 +00007635 if (FCmpInst *FCI = dyn_cast<FCmpInst>(CondVal)) {
7636 if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) {
Chris Lattner623fba12004-04-10 22:21:27 +00007637 // Transform (X == Y) ? X : Y -> Y
Reid Spencer266e42b2006-12-23 06:05:41 +00007638 if (FCI->getPredicate() == FCmpInst::FCMP_OEQ)
Chris Lattner623fba12004-04-10 22:21:27 +00007639 return ReplaceInstUsesWith(SI, FalseVal);
7640 // Transform (X != Y) ? X : Y -> X
Reid Spencer266e42b2006-12-23 06:05:41 +00007641 if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
Chris Lattner623fba12004-04-10 22:21:27 +00007642 return ReplaceInstUsesWith(SI, TrueVal);
7643 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
7644
Reid Spencer266e42b2006-12-23 06:05:41 +00007645 } else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){
Chris Lattner623fba12004-04-10 22:21:27 +00007646 // Transform (X == Y) ? Y : X -> X
Reid Spencer266e42b2006-12-23 06:05:41 +00007647 if (FCI->getPredicate() == FCmpInst::FCMP_OEQ)
Chris Lattner24cf0202004-04-11 01:39:19 +00007648 return ReplaceInstUsesWith(SI, FalseVal);
Chris Lattner623fba12004-04-10 22:21:27 +00007649 // Transform (X != Y) ? Y : X -> Y
Reid Spencer266e42b2006-12-23 06:05:41 +00007650 if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
7651 return ReplaceInstUsesWith(SI, TrueVal);
7652 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
7653 }
7654 }
7655
7656 // See if we are selecting two values based on a comparison of the two values.
7657 if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal)) {
7658 if (ICI->getOperand(0) == TrueVal && ICI->getOperand(1) == FalseVal) {
7659 // Transform (X == Y) ? X : Y -> Y
7660 if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
7661 return ReplaceInstUsesWith(SI, FalseVal);
7662 // Transform (X != Y) ? X : Y -> X
7663 if (ICI->getPredicate() == ICmpInst::ICMP_NE)
7664 return ReplaceInstUsesWith(SI, TrueVal);
7665 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
7666
7667 } else if (ICI->getOperand(0) == FalseVal && ICI->getOperand(1) == TrueVal){
7668 // Transform (X == Y) ? Y : X -> X
7669 if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
7670 return ReplaceInstUsesWith(SI, FalseVal);
7671 // Transform (X != Y) ? Y : X -> Y
7672 if (ICI->getPredicate() == ICmpInst::ICMP_NE)
Chris Lattner24cf0202004-04-11 01:39:19 +00007673 return ReplaceInstUsesWith(SI, TrueVal);
Chris Lattner623fba12004-04-10 22:21:27 +00007674 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
7675 }
7676 }
Misha Brukmanb1c93172005-04-21 23:48:37 +00007677
Chris Lattnera04c9042005-01-13 22:52:24 +00007678 if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
7679 if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
7680 if (TI->hasOneUse() && FI->hasOneUse()) {
Chris Lattnera04c9042005-01-13 22:52:24 +00007681 Instruction *AddOp = 0, *SubOp = 0;
7682
Chris Lattner411336f2005-01-19 21:50:18 +00007683 // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
7684 if (TI->getOpcode() == FI->getOpcode())
7685 if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
7686 return IV;
7687
7688 // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
7689 // even legal for FP.
Chris Lattnera04c9042005-01-13 22:52:24 +00007690 if (TI->getOpcode() == Instruction::Sub &&
7691 FI->getOpcode() == Instruction::Add) {
7692 AddOp = FI; SubOp = TI;
7693 } else if (FI->getOpcode() == Instruction::Sub &&
7694 TI->getOpcode() == Instruction::Add) {
7695 AddOp = TI; SubOp = FI;
7696 }
7697
7698 if (AddOp) {
7699 Value *OtherAddOp = 0;
7700 if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
7701 OtherAddOp = AddOp->getOperand(1);
7702 } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
7703 OtherAddOp = AddOp->getOperand(0);
7704 }
7705
7706 if (OtherAddOp) {
Chris Lattnerb580d262006-02-24 18:05:58 +00007707 // So at this point we know we have (Y -> OtherAddOp):
7708 // select C, (add X, Y), (sub X, Z)
7709 Value *NegVal; // Compute -Z
7710 if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
7711 NegVal = ConstantExpr::getNeg(C);
7712 } else {
7713 NegVal = InsertNewInstBefore(
7714 BinaryOperator::createNeg(SubOp->getOperand(1), "tmp"), SI);
Chris Lattnera04c9042005-01-13 22:52:24 +00007715 }
Chris Lattnerb580d262006-02-24 18:05:58 +00007716
7717 Value *NewTrueOp = OtherAddOp;
7718 Value *NewFalseOp = NegVal;
7719 if (AddOp != TI)
7720 std::swap(NewTrueOp, NewFalseOp);
7721 Instruction *NewSel =
7722 new SelectInst(CondVal, NewTrueOp,NewFalseOp,SI.getName()+".p");
7723
7724 NewSel = InsertNewInstBefore(NewSel, SI);
7725 return BinaryOperator::createAdd(SubOp->getOperand(0), NewSel);
Chris Lattnera04c9042005-01-13 22:52:24 +00007726 }
7727 }
7728 }
Misha Brukmanb1c93172005-04-21 23:48:37 +00007729
Chris Lattner56e4d3d2004-04-09 23:46:01 +00007730 // See if we can fold the select into one of our operands.
Chris Lattner03c49532007-01-15 02:27:26 +00007731 if (SI.getType()->isInteger()) {
Chris Lattner56e4d3d2004-04-09 23:46:01 +00007732 // See the comment above GetSelectFoldableOperands for a description of the
7733 // transformation we are doing here.
7734 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
7735 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
7736 !isa<Constant>(FalseVal))
7737 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
7738 unsigned OpToFold = 0;
7739 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
7740 OpToFold = 1;
7741 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
7742 OpToFold = 2;
7743 }
7744
7745 if (OpToFold) {
7746 Constant *C = GetSelectFoldableConstant(TVI);
Chris Lattner56e4d3d2004-04-09 23:46:01 +00007747 Instruction *NewSel =
Chris Lattner6e0123b2007-02-11 01:23:03 +00007748 new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C);
Chris Lattner56e4d3d2004-04-09 23:46:01 +00007749 InsertNewInstBefore(NewSel, SI);
Chris Lattner6e0123b2007-02-11 01:23:03 +00007750 NewSel->takeName(TVI);
Chris Lattner56e4d3d2004-04-09 23:46:01 +00007751 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
7752 return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
Chris Lattner56e4d3d2004-04-09 23:46:01 +00007753 else {
7754 assert(0 && "Unknown instruction!!");
7755 }
7756 }
7757 }
Chris Lattner6862fbd2004-09-29 17:40:11 +00007758
Chris Lattner56e4d3d2004-04-09 23:46:01 +00007759 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
7760 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
7761 !isa<Constant>(TrueVal))
7762 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
7763 unsigned OpToFold = 0;
7764 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
7765 OpToFold = 1;
7766 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
7767 OpToFold = 2;
7768 }
7769
7770 if (OpToFold) {
7771 Constant *C = GetSelectFoldableConstant(FVI);
Chris Lattner56e4d3d2004-04-09 23:46:01 +00007772 Instruction *NewSel =
Chris Lattner6e0123b2007-02-11 01:23:03 +00007773 new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold));
Chris Lattner56e4d3d2004-04-09 23:46:01 +00007774 InsertNewInstBefore(NewSel, SI);
Chris Lattner6e0123b2007-02-11 01:23:03 +00007775 NewSel->takeName(FVI);
Chris Lattner56e4d3d2004-04-09 23:46:01 +00007776 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
7777 return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
Reid Spencer2341c222007-02-02 02:16:23 +00007778 else
Chris Lattner56e4d3d2004-04-09 23:46:01 +00007779 assert(0 && "Unknown instruction!!");
Chris Lattner56e4d3d2004-04-09 23:46:01 +00007780 }
7781 }
7782 }
Chris Lattnerd6f636a2005-04-24 07:30:14 +00007783
7784 if (BinaryOperator::isNot(CondVal)) {
7785 SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
7786 SI.setOperand(1, FalseVal);
7787 SI.setOperand(2, TrueVal);
7788 return &SI;
7789 }
7790
Chris Lattnerb909e8b2004-03-12 05:52:32 +00007791 return 0;
7792}
7793
Chris Lattner82f2ef22006-03-06 20:18:44 +00007794/// GetKnownAlignment - If the specified pointer has an alignment that we can
7795/// determine, return it, otherwise return 0.
7796static unsigned GetKnownAlignment(Value *V, TargetData *TD) {
7797 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
7798 unsigned Align = GV->getAlignment();
7799 if (Align == 0 && TD)
Chris Lattner945e4372007-02-14 05:52:17 +00007800 Align = TD->getPrefTypeAlignment(GV->getType()->getElementType());
Chris Lattner82f2ef22006-03-06 20:18:44 +00007801 return Align;
7802 } else if (AllocationInst *AI = dyn_cast<AllocationInst>(V)) {
7803 unsigned Align = AI->getAlignment();
7804 if (Align == 0 && TD) {
7805 if (isa<AllocaInst>(AI))
Chris Lattner945e4372007-02-14 05:52:17 +00007806 Align = TD->getPrefTypeAlignment(AI->getType()->getElementType());
Chris Lattner82f2ef22006-03-06 20:18:44 +00007807 else if (isa<MallocInst>(AI)) {
7808 // Malloc returns maximally aligned memory.
Chris Lattner945e4372007-02-14 05:52:17 +00007809 Align = TD->getABITypeAlignment(AI->getType()->getElementType());
Chris Lattner50ee0e42007-01-20 22:35:55 +00007810 Align =
7811 std::max(Align,
Chris Lattner945e4372007-02-14 05:52:17 +00007812 (unsigned)TD->getABITypeAlignment(Type::DoubleTy));
Chris Lattner50ee0e42007-01-20 22:35:55 +00007813 Align =
7814 std::max(Align,
Chris Lattner945e4372007-02-14 05:52:17 +00007815 (unsigned)TD->getABITypeAlignment(Type::Int64Ty));
Chris Lattner82f2ef22006-03-06 20:18:44 +00007816 }
7817 }
7818 return Align;
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007819 } else if (isa<BitCastInst>(V) ||
Chris Lattner53ef5a02006-03-07 01:28:57 +00007820 (isa<ConstantExpr>(V) &&
Reid Spencer6c38f0b2006-11-27 01:05:10 +00007821 cast<ConstantExpr>(V)->getOpcode() == Instruction::BitCast)) {
Chris Lattner53ef5a02006-03-07 01:28:57 +00007822 User *CI = cast<User>(V);
Chris Lattner82f2ef22006-03-06 20:18:44 +00007823 if (isa<PointerType>(CI->getOperand(0)->getType()))
7824 return GetKnownAlignment(CI->getOperand(0), TD);
7825 return 0;
Chris Lattner53ef5a02006-03-07 01:28:57 +00007826 } else if (isa<GetElementPtrInst>(V) ||
7827 (isa<ConstantExpr>(V) &&
7828 cast<ConstantExpr>(V)->getOpcode()==Instruction::GetElementPtr)) {
7829 User *GEPI = cast<User>(V);
Chris Lattner82f2ef22006-03-06 20:18:44 +00007830 unsigned BaseAlignment = GetKnownAlignment(GEPI->getOperand(0), TD);
7831 if (BaseAlignment == 0) return 0;
7832
7833 // If all indexes are zero, it is just the alignment of the base pointer.
7834 bool AllZeroOperands = true;
7835 for (unsigned i = 1, e = GEPI->getNumOperands(); i != e; ++i)
7836 if (!isa<Constant>(GEPI->getOperand(i)) ||
7837 !cast<Constant>(GEPI->getOperand(i))->isNullValue()) {
7838 AllZeroOperands = false;
7839 break;
7840 }
7841 if (AllZeroOperands)
7842 return BaseAlignment;
7843
7844 // Otherwise, if the base alignment is >= the alignment we expect for the
7845 // base pointer type, then we know that the resultant pointer is aligned at
7846 // least as much as its type requires.
7847 if (!TD) return 0;
7848
7849 const Type *BasePtrTy = GEPI->getOperand(0)->getType();
Chris Lattner50ee0e42007-01-20 22:35:55 +00007850 const PointerType *PtrTy = cast<PointerType>(BasePtrTy);
Chris Lattner945e4372007-02-14 05:52:17 +00007851 if (TD->getABITypeAlignment(PtrTy->getElementType())
Chris Lattner53ef5a02006-03-07 01:28:57 +00007852 <= BaseAlignment) {
7853 const Type *GEPTy = GEPI->getType();
Chris Lattner50ee0e42007-01-20 22:35:55 +00007854 const PointerType *GEPPtrTy = cast<PointerType>(GEPTy);
Chris Lattner945e4372007-02-14 05:52:17 +00007855 return TD->getABITypeAlignment(GEPPtrTy->getElementType());
Chris Lattner53ef5a02006-03-07 01:28:57 +00007856 }
Chris Lattner82f2ef22006-03-06 20:18:44 +00007857 return 0;
7858 }
7859 return 0;
7860}
7861
Chris Lattnerb909e8b2004-03-12 05:52:32 +00007862
Chris Lattnerc66b2232006-01-13 20:11:04 +00007863/// visitCallInst - CallInst simplification. This mostly only handles folding
7864/// of intrinsic instructions. For normal calls, it allows visitCallSite to do
7865/// the heavy lifting.
7866///
Chris Lattner970c33a2003-06-19 17:00:31 +00007867Instruction *InstCombiner::visitCallInst(CallInst &CI) {
Chris Lattnerc66b2232006-01-13 20:11:04 +00007868 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI);
7869 if (!II) return visitCallSite(&CI);
7870
Chris Lattner51ea1272004-02-28 05:22:00 +00007871 // Intrinsics cannot occur in an invoke, so handle them here instead of in
7872 // visitCallSite.
Chris Lattnerc66b2232006-01-13 20:11:04 +00007873 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) {
Chris Lattner00648e12004-10-12 04:52:52 +00007874 bool Changed = false;
7875
7876 // memmove/cpy/set of zero bytes is a noop.
7877 if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
7878 if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
7879
Chris Lattner00648e12004-10-12 04:52:52 +00007880 if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
Reid Spencere0fc4df2006-10-20 07:07:24 +00007881 if (CI->getZExtValue() == 1) {
Chris Lattner00648e12004-10-12 04:52:52 +00007882 // Replace the instruction with just byte operations. We would
7883 // transform other cases to loads/stores, but we don't know if
7884 // alignment is sufficient.
7885 }
Chris Lattner51ea1272004-02-28 05:22:00 +00007886 }
7887
Chris Lattner00648e12004-10-12 04:52:52 +00007888 // If we have a memmove and the source operation is a constant global,
7889 // then the source and dest pointers can't alias, so we can change this
7890 // into a call to memcpy.
Chris Lattner82f2ef22006-03-06 20:18:44 +00007891 if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(II)) {
Chris Lattner00648e12004-10-12 04:52:52 +00007892 if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
7893 if (GVSrc->isConstant()) {
7894 Module *M = CI.getParent()->getParent()->getParent();
Chris Lattner681ef2f2006-03-03 01:34:17 +00007895 const char *Name;
Andrew Lenharth0ebb0b02006-11-03 22:45:50 +00007896 if (CI.getCalledFunction()->getFunctionType()->getParamType(2) ==
Reid Spencerc635f472006-12-31 05:48:39 +00007897 Type::Int32Ty)
Chris Lattner681ef2f2006-03-03 01:34:17 +00007898 Name = "llvm.memcpy.i32";
7899 else
7900 Name = "llvm.memcpy.i64";
Chris Lattnerfbc524f2007-01-07 06:58:05 +00007901 Constant *MemCpy = M->getOrInsertFunction(Name,
Chris Lattner00648e12004-10-12 04:52:52 +00007902 CI.getCalledFunction()->getFunctionType());
7903 CI.setOperand(0, MemCpy);
7904 Changed = true;
7905 }
Chris Lattner82f2ef22006-03-06 20:18:44 +00007906 }
Chris Lattner00648e12004-10-12 04:52:52 +00007907
Chris Lattner82f2ef22006-03-06 20:18:44 +00007908 // If we can determine a pointer alignment that is bigger than currently
7909 // set, update the alignment.
7910 if (isa<MemCpyInst>(MI) || isa<MemMoveInst>(MI)) {
7911 unsigned Alignment1 = GetKnownAlignment(MI->getOperand(1), TD);
7912 unsigned Alignment2 = GetKnownAlignment(MI->getOperand(2), TD);
7913 unsigned Align = std::min(Alignment1, Alignment2);
Reid Spencere0fc4df2006-10-20 07:07:24 +00007914 if (MI->getAlignment()->getZExtValue() < Align) {
Reid Spencerc635f472006-12-31 05:48:39 +00007915 MI->setAlignment(ConstantInt::get(Type::Int32Ty, Align));
Chris Lattner82f2ef22006-03-06 20:18:44 +00007916 Changed = true;
7917 }
7918 } else if (isa<MemSetInst>(MI)) {
7919 unsigned Alignment = GetKnownAlignment(MI->getDest(), TD);
Reid Spencere0fc4df2006-10-20 07:07:24 +00007920 if (MI->getAlignment()->getZExtValue() < Alignment) {
Reid Spencerc635f472006-12-31 05:48:39 +00007921 MI->setAlignment(ConstantInt::get(Type::Int32Ty, Alignment));
Chris Lattner82f2ef22006-03-06 20:18:44 +00007922 Changed = true;
7923 }
7924 }
7925
Chris Lattnerc66b2232006-01-13 20:11:04 +00007926 if (Changed) return II;
Chris Lattner503221f2006-01-13 21:28:09 +00007927 } else {
7928 switch (II->getIntrinsicID()) {
7929 default: break;
Chris Lattnerf42d0ae2006-04-02 05:30:25 +00007930 case Intrinsic::ppc_altivec_lvx:
7931 case Intrinsic::ppc_altivec_lvxl:
Chris Lattner36dd7c92006-04-17 22:26:56 +00007932 case Intrinsic::x86_sse_loadu_ps:
7933 case Intrinsic::x86_sse2_loadu_pd:
7934 case Intrinsic::x86_sse2_loadu_dq:
7935 // Turn PPC lvx -> load if the pointer is known aligned.
7936 // Turn X86 loadups -> load if the pointer is known aligned.
Chris Lattnerf42d0ae2006-04-02 05:30:25 +00007937 if (GetKnownAlignment(II->getOperand(1), TD) >= 16) {
Reid Spencer13bc5d72006-12-12 09:18:51 +00007938 Value *Ptr = InsertCastBefore(Instruction::BitCast, II->getOperand(1),
Chris Lattnere79d2492006-04-06 19:19:17 +00007939 PointerType::get(II->getType()), CI);
Chris Lattnerf42d0ae2006-04-02 05:30:25 +00007940 return new LoadInst(Ptr);
7941 }
7942 break;
7943 case Intrinsic::ppc_altivec_stvx:
7944 case Intrinsic::ppc_altivec_stvxl:
7945 // Turn stvx -> store if the pointer is known aligned.
7946 if (GetKnownAlignment(II->getOperand(2), TD) >= 16) {
Chris Lattnere79d2492006-04-06 19:19:17 +00007947 const Type *OpPtrTy = PointerType::get(II->getOperand(1)->getType());
Reid Spencer13bc5d72006-12-12 09:18:51 +00007948 Value *Ptr = InsertCastBefore(Instruction::BitCast, II->getOperand(2),
7949 OpPtrTy, CI);
Chris Lattnerf42d0ae2006-04-02 05:30:25 +00007950 return new StoreInst(II->getOperand(1), Ptr);
7951 }
7952 break;
Chris Lattner36dd7c92006-04-17 22:26:56 +00007953 case Intrinsic::x86_sse_storeu_ps:
7954 case Intrinsic::x86_sse2_storeu_pd:
7955 case Intrinsic::x86_sse2_storeu_dq:
7956 case Intrinsic::x86_sse2_storel_dq:
7957 // Turn X86 storeu -> store if the pointer is known aligned.
7958 if (GetKnownAlignment(II->getOperand(1), TD) >= 16) {
7959 const Type *OpPtrTy = PointerType::get(II->getOperand(2)->getType());
Reid Spencer13bc5d72006-12-12 09:18:51 +00007960 Value *Ptr = InsertCastBefore(Instruction::BitCast, II->getOperand(1),
7961 OpPtrTy, CI);
Chris Lattner36dd7c92006-04-17 22:26:56 +00007962 return new StoreInst(II->getOperand(2), Ptr);
7963 }
7964 break;
Chris Lattner2deeaea2006-10-05 06:55:50 +00007965
7966 case Intrinsic::x86_sse_cvttss2si: {
7967 // These intrinsics only demands the 0th element of its input vector. If
7968 // we can simplify the input based on that, do so now.
7969 uint64_t UndefElts;
7970 if (Value *V = SimplifyDemandedVectorElts(II->getOperand(1), 1,
7971 UndefElts)) {
7972 II->setOperand(1, V);
7973 return II;
7974 }
7975 break;
7976 }
7977
Chris Lattnere79d2492006-04-06 19:19:17 +00007978 case Intrinsic::ppc_altivec_vperm:
7979 // Turn vperm(V1,V2,mask) -> shuffle(V1,V2,mask) if mask is a constant.
Reid Spencerd84d35b2007-02-15 02:26:10 +00007980 if (ConstantVector *Mask = dyn_cast<ConstantVector>(II->getOperand(3))) {
Chris Lattnere79d2492006-04-06 19:19:17 +00007981 assert(Mask->getNumOperands() == 16 && "Bad type for intrinsic!");
7982
7983 // Check that all of the elements are integer constants or undefs.
7984 bool AllEltsOk = true;
7985 for (unsigned i = 0; i != 16; ++i) {
7986 if (!isa<ConstantInt>(Mask->getOperand(i)) &&
7987 !isa<UndefValue>(Mask->getOperand(i))) {
7988 AllEltsOk = false;
7989 break;
7990 }
7991 }
7992
7993 if (AllEltsOk) {
7994 // Cast the input vectors to byte vectors.
Reid Spencer13bc5d72006-12-12 09:18:51 +00007995 Value *Op0 = InsertCastBefore(Instruction::BitCast,
7996 II->getOperand(1), Mask->getType(), CI);
7997 Value *Op1 = InsertCastBefore(Instruction::BitCast,
7998 II->getOperand(2), Mask->getType(), CI);
Chris Lattnere79d2492006-04-06 19:19:17 +00007999 Value *Result = UndefValue::get(Op0->getType());
8000
8001 // Only extract each element once.
8002 Value *ExtractedElts[32];
8003 memset(ExtractedElts, 0, sizeof(ExtractedElts));
8004
8005 for (unsigned i = 0; i != 16; ++i) {
8006 if (isa<UndefValue>(Mask->getOperand(i)))
8007 continue;
Reid Spencere0fc4df2006-10-20 07:07:24 +00008008 unsigned Idx =cast<ConstantInt>(Mask->getOperand(i))->getZExtValue();
Chris Lattnere79d2492006-04-06 19:19:17 +00008009 Idx &= 31; // Match the hardware behavior.
8010
8011 if (ExtractedElts[Idx] == 0) {
8012 Instruction *Elt =
Chris Lattner2deeaea2006-10-05 06:55:50 +00008013 new ExtractElementInst(Idx < 16 ? Op0 : Op1, Idx&15, "tmp");
Chris Lattnere79d2492006-04-06 19:19:17 +00008014 InsertNewInstBefore(Elt, CI);
8015 ExtractedElts[Idx] = Elt;
8016 }
8017
8018 // Insert this value into the result vector.
Chris Lattner2deeaea2006-10-05 06:55:50 +00008019 Result = new InsertElementInst(Result, ExtractedElts[Idx], i,"tmp");
Chris Lattnere79d2492006-04-06 19:19:17 +00008020 InsertNewInstBefore(cast<Instruction>(Result), CI);
8021 }
Reid Spencer6c38f0b2006-11-27 01:05:10 +00008022 return CastInst::create(Instruction::BitCast, Result, CI.getType());
Chris Lattnere79d2492006-04-06 19:19:17 +00008023 }
8024 }
8025 break;
8026
Chris Lattner503221f2006-01-13 21:28:09 +00008027 case Intrinsic::stackrestore: {
8028 // If the save is right next to the restore, remove the restore. This can
8029 // happen when variable allocas are DCE'd.
8030 if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getOperand(1))) {
8031 if (SS->getIntrinsicID() == Intrinsic::stacksave) {
8032 BasicBlock::iterator BI = SS;
8033 if (&*++BI == II)
8034 return EraseInstFromFunction(CI);
8035 }
8036 }
8037
8038 // If the stack restore is in a return/unwind block and if there are no
8039 // allocas or calls between the restore and the return, nuke the restore.
8040 TerminatorInst *TI = II->getParent()->getTerminator();
8041 if (isa<ReturnInst>(TI) || isa<UnwindInst>(TI)) {
8042 BasicBlock::iterator BI = II;
8043 bool CannotRemove = false;
8044 for (++BI; &*BI != TI; ++BI) {
8045 if (isa<AllocaInst>(BI) ||
8046 (isa<CallInst>(BI) && !isa<IntrinsicInst>(BI))) {
8047 CannotRemove = true;
8048 break;
8049 }
8050 }
8051 if (!CannotRemove)
8052 return EraseInstFromFunction(CI);
8053 }
8054 break;
8055 }
8056 }
Chris Lattner00648e12004-10-12 04:52:52 +00008057 }
8058
Chris Lattnerc66b2232006-01-13 20:11:04 +00008059 return visitCallSite(II);
Chris Lattner970c33a2003-06-19 17:00:31 +00008060}
8061
8062// InvokeInst simplification
8063//
8064Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
Chris Lattneraec3d942003-10-07 22:32:43 +00008065 return visitCallSite(&II);
Chris Lattner970c33a2003-06-19 17:00:31 +00008066}
8067
Chris Lattneraec3d942003-10-07 22:32:43 +00008068// visitCallSite - Improvements for call and invoke instructions.
8069//
8070Instruction *InstCombiner::visitCallSite(CallSite CS) {
Chris Lattner75b4d1d2003-10-07 22:54:13 +00008071 bool Changed = false;
8072
8073 // If the callee is a constexpr cast of a function, attempt to move the cast
8074 // to the arguments of the call/invoke.
Chris Lattneraec3d942003-10-07 22:32:43 +00008075 if (transformConstExprCastCall(CS)) return 0;
8076
Chris Lattner75b4d1d2003-10-07 22:54:13 +00008077 Value *Callee = CS.getCalledValue();
Chris Lattner81a7a232004-10-16 18:11:37 +00008078
Chris Lattner61d9d812005-05-13 07:09:09 +00008079 if (Function *CalleeF = dyn_cast<Function>(Callee))
8080 if (CalleeF->getCallingConv() != CS.getCallingConv()) {
8081 Instruction *OldCall = CS.getInstruction();
8082 // If the call and callee calling conventions don't match, this call must
8083 // be unreachable, as the call is undefined.
Zhou Sheng75b871f2007-01-11 12:24:14 +00008084 new StoreInst(ConstantInt::getTrue(),
Reid Spencer542964f2007-01-11 18:21:29 +00008085 UndefValue::get(PointerType::get(Type::Int1Ty)), OldCall);
Chris Lattner61d9d812005-05-13 07:09:09 +00008086 if (!OldCall->use_empty())
8087 OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
8088 if (isa<CallInst>(OldCall)) // Not worth removing an invoke here.
8089 return EraseInstFromFunction(*OldCall);
8090 return 0;
8091 }
8092
Chris Lattner8ba9ec92004-10-18 02:59:09 +00008093 if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
8094 // This instruction is not reachable, just remove it. We insert a store to
8095 // undef so that we know that this code is not reachable, despite the fact
8096 // that we can't modify the CFG here.
Zhou Sheng75b871f2007-01-11 12:24:14 +00008097 new StoreInst(ConstantInt::getTrue(),
Reid Spencer542964f2007-01-11 18:21:29 +00008098 UndefValue::get(PointerType::get(Type::Int1Ty)),
Chris Lattner8ba9ec92004-10-18 02:59:09 +00008099 CS.getInstruction());
8100
8101 if (!CS.getInstruction()->use_empty())
8102 CS.getInstruction()->
8103 replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
8104
8105 if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
8106 // Don't break the CFG, insert a dummy cond branch.
8107 new BranchInst(II->getNormalDest(), II->getUnwindDest(),
Zhou Sheng75b871f2007-01-11 12:24:14 +00008108 ConstantInt::getTrue(), II);
Chris Lattner81a7a232004-10-16 18:11:37 +00008109 }
Chris Lattner8ba9ec92004-10-18 02:59:09 +00008110 return EraseInstFromFunction(*CS.getInstruction());
8111 }
Chris Lattner81a7a232004-10-16 18:11:37 +00008112
Chris Lattner75b4d1d2003-10-07 22:54:13 +00008113 const PointerType *PTy = cast<PointerType>(Callee->getType());
8114 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
8115 if (FTy->isVarArg()) {
8116 // See if we can optimize any arguments passed through the varargs area of
8117 // the call.
8118 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
8119 E = CS.arg_end(); I != E; ++I)
8120 if (CastInst *CI = dyn_cast<CastInst>(*I)) {
8121 // If this cast does not effect the value passed through the varargs
8122 // area, we can eliminate the use of the cast.
8123 Value *Op = CI->getOperand(0);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00008124 if (CI->isLosslessCast()) {
Chris Lattner75b4d1d2003-10-07 22:54:13 +00008125 *I = Op;
8126 Changed = true;
8127 }
8128 }
8129 }
Misha Brukmanb1c93172005-04-21 23:48:37 +00008130
Chris Lattner75b4d1d2003-10-07 22:54:13 +00008131 return Changed ? CS.getInstruction() : 0;
Chris Lattneraec3d942003-10-07 22:32:43 +00008132}
8133
Chris Lattner970c33a2003-06-19 17:00:31 +00008134// transformConstExprCastCall - If the callee is a constexpr cast of a function,
8135// attempt to move the cast to the arguments of the call/invoke.
8136//
8137bool InstCombiner::transformConstExprCastCall(CallSite CS) {
8138 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
8139 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
Reid Spencer6c38f0b2006-11-27 01:05:10 +00008140 if (CE->getOpcode() != Instruction::BitCast ||
8141 !isa<Function>(CE->getOperand(0)))
Chris Lattner970c33a2003-06-19 17:00:31 +00008142 return false;
Reid Spencer87436872004-07-18 00:38:32 +00008143 Function *Callee = cast<Function>(CE->getOperand(0));
Chris Lattner970c33a2003-06-19 17:00:31 +00008144 Instruction *Caller = CS.getInstruction();
8145
8146 // Okay, this is a cast from a function to a different type. Unless doing so
8147 // would cause a type conversion of one of our arguments, change this call to
8148 // be a direct call with arguments casted to the appropriate types.
8149 //
8150 const FunctionType *FT = Callee->getFunctionType();
8151 const Type *OldRetTy = Caller->getType();
8152
Chris Lattner1f7942f2004-01-14 06:06:08 +00008153 // Check to see if we are changing the return type...
8154 if (OldRetTy != FT->getReturnType()) {
Reid Spencer5301e7c2007-01-30 20:08:39 +00008155 if (Callee->isDeclaration() && !Caller->use_empty() &&
Chris Lattner7051d752007-01-06 19:53:32 +00008156 // Conversion is ok if changing from pointer to int of same size.
8157 !(isa<PointerType>(FT->getReturnType()) &&
8158 TD->getIntPtrType() == OldRetTy))
Chris Lattner400f9592007-01-06 02:09:32 +00008159 return false; // Cannot transform this return value.
Chris Lattner1f7942f2004-01-14 06:06:08 +00008160
8161 // If the callsite is an invoke instruction, and the return value is used by
8162 // a PHI node in a successor, we cannot change the return type of the call
8163 // because there is no place to put the cast instruction (without breaking
8164 // the critical edge). Bail out in this case.
8165 if (!Caller->use_empty())
8166 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
8167 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
8168 UI != E; ++UI)
8169 if (PHINode *PN = dyn_cast<PHINode>(*UI))
8170 if (PN->getParent() == II->getNormalDest() ||
Chris Lattnerfae8ab32004-02-08 21:44:31 +00008171 PN->getParent() == II->getUnwindDest())
Chris Lattner1f7942f2004-01-14 06:06:08 +00008172 return false;
8173 }
Chris Lattner970c33a2003-06-19 17:00:31 +00008174
8175 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
8176 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
Misha Brukmanb1c93172005-04-21 23:48:37 +00008177
Chris Lattner970c33a2003-06-19 17:00:31 +00008178 CallSite::arg_iterator AI = CS.arg_begin();
8179 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
8180 const Type *ParamTy = FT->getParamType(i);
Andrew Lenharthebfa24e2006-06-28 01:01:52 +00008181 const Type *ActTy = (*AI)->getType();
Reid Spencer6c38f0b2006-11-27 01:05:10 +00008182 ConstantInt *c = dyn_cast<ConstantInt>(*AI);
Andrew Lenharthebfa24e2006-06-28 01:01:52 +00008183 //Either we can cast directly, or we can upconvert the argument
Chris Lattner400f9592007-01-06 02:09:32 +00008184 bool isConvertible = ActTy == ParamTy ||
Chris Lattner7051d752007-01-06 19:53:32 +00008185 (isa<PointerType>(ParamTy) && isa<PointerType>(ActTy)) ||
Chris Lattner03c49532007-01-15 02:27:26 +00008186 (ParamTy->isInteger() && ActTy->isInteger() &&
Reid Spencer8f166b02007-01-08 16:32:00 +00008187 ParamTy->getPrimitiveSizeInBits() >= ActTy->getPrimitiveSizeInBits()) ||
8188 (c && ParamTy->getPrimitiveSizeInBits() >= ActTy->getPrimitiveSizeInBits()
8189 && c->getSExtValue() > 0);
Reid Spencer5301e7c2007-01-30 20:08:39 +00008190 if (Callee->isDeclaration() && !isConvertible) return false;
Chris Lattner970c33a2003-06-19 17:00:31 +00008191 }
8192
8193 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
Reid Spencer5301e7c2007-01-30 20:08:39 +00008194 Callee->isDeclaration())
Chris Lattner970c33a2003-06-19 17:00:31 +00008195 return false; // Do not delete arguments unless we have a function body...
8196
8197 // Okay, we decided that this is a safe thing to do: go ahead and start
8198 // inserting cast instructions as necessary...
8199 std::vector<Value*> Args;
8200 Args.reserve(NumActualArgs);
8201
8202 AI = CS.arg_begin();
8203 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
8204 const Type *ParamTy = FT->getParamType(i);
8205 if ((*AI)->getType() == ParamTy) {
8206 Args.push_back(*AI);
8207 } else {
Reid Spencer668d90f2006-12-18 08:47:13 +00008208 Instruction::CastOps opcode = CastInst::getCastOpcode(*AI,
Reid Spencerc635f472006-12-31 05:48:39 +00008209 false, ParamTy, false);
Reid Spencer668d90f2006-12-18 08:47:13 +00008210 CastInst *NewCast = CastInst::create(opcode, *AI, ParamTy, "tmp");
Reid Spencer6c38f0b2006-11-27 01:05:10 +00008211 Args.push_back(InsertNewInstBefore(NewCast, *Caller));
Chris Lattner970c33a2003-06-19 17:00:31 +00008212 }
8213 }
8214
8215 // If the function takes more arguments than the call was taking, add them
8216 // now...
8217 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
8218 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
8219
8220 // If we are removing arguments to the function, emit an obnoxious warning...
8221 if (FT->getNumParams() < NumActualArgs)
8222 if (!FT->isVarArg()) {
Bill Wendlingf3baad32006-12-07 01:30:32 +00008223 cerr << "WARNING: While resolving call to function '"
8224 << Callee->getName() << "' arguments were dropped!\n";
Chris Lattner970c33a2003-06-19 17:00:31 +00008225 } else {
8226 // Add all of the arguments in their promoted form to the arg list...
8227 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
8228 const Type *PTy = getPromotedType((*AI)->getType());
8229 if (PTy != (*AI)->getType()) {
8230 // Must promote to pass through va_arg area!
Reid Spencerc635f472006-12-31 05:48:39 +00008231 Instruction::CastOps opcode = CastInst::getCastOpcode(*AI, false,
8232 PTy, false);
Reid Spencer668d90f2006-12-18 08:47:13 +00008233 Instruction *Cast = CastInst::create(opcode, *AI, PTy, "tmp");
Chris Lattner970c33a2003-06-19 17:00:31 +00008234 InsertNewInstBefore(Cast, *Caller);
8235 Args.push_back(Cast);
8236 } else {
8237 Args.push_back(*AI);
8238 }
8239 }
8240 }
8241
8242 if (FT->getReturnType() == Type::VoidTy)
Chris Lattner6e0123b2007-02-11 01:23:03 +00008243 Caller->setName(""); // Void type should not have a name.
Chris Lattner970c33a2003-06-19 17:00:31 +00008244
8245 Instruction *NC;
8246 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
Chris Lattnerfae8ab32004-02-08 21:44:31 +00008247 NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
Chris Lattnera06a8fd2007-02-13 02:10:56 +00008248 &Args[0], Args.size(), Caller->getName(), Caller);
Chris Lattner05c703e2005-05-14 12:25:32 +00008249 cast<InvokeInst>(II)->setCallingConv(II->getCallingConv());
Chris Lattner970c33a2003-06-19 17:00:31 +00008250 } else {
Chris Lattnera06a8fd2007-02-13 02:10:56 +00008251 NC = new CallInst(Callee, &Args[0], Args.size(), Caller->getName(), Caller);
Chris Lattner6aacb0f2005-05-06 06:48:21 +00008252 if (cast<CallInst>(Caller)->isTailCall())
8253 cast<CallInst>(NC)->setTailCall();
Chris Lattner05c703e2005-05-14 12:25:32 +00008254 cast<CallInst>(NC)->setCallingConv(cast<CallInst>(Caller)->getCallingConv());
Chris Lattner970c33a2003-06-19 17:00:31 +00008255 }
8256
Chris Lattner6e0123b2007-02-11 01:23:03 +00008257 // Insert a cast of the return type as necessary.
Chris Lattner970c33a2003-06-19 17:00:31 +00008258 Value *NV = NC;
8259 if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
8260 if (NV->getType() != Type::VoidTy) {
Reid Spencer668d90f2006-12-18 08:47:13 +00008261 const Type *CallerTy = Caller->getType();
Reid Spencerc635f472006-12-31 05:48:39 +00008262 Instruction::CastOps opcode = CastInst::getCastOpcode(NC, false,
8263 CallerTy, false);
Reid Spencer668d90f2006-12-18 08:47:13 +00008264 NV = NC = CastInst::create(opcode, NC, CallerTy, "tmp");
Chris Lattner686767f2003-10-30 00:46:41 +00008265
8266 // If this is an invoke instruction, we should insert it after the first
8267 // non-phi, instruction in the normal successor block.
8268 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
8269 BasicBlock::iterator I = II->getNormalDest()->begin();
8270 while (isa<PHINode>(I)) ++I;
8271 InsertNewInstBefore(NC, *I);
8272 } else {
8273 // Otherwise, it's a call, just insert cast right after the call instr
8274 InsertNewInstBefore(NC, *Caller);
8275 }
Chris Lattner51ea1272004-02-28 05:22:00 +00008276 AddUsersToWorkList(*Caller);
Chris Lattner970c33a2003-06-19 17:00:31 +00008277 } else {
Chris Lattnere29d6342004-10-17 21:22:38 +00008278 NV = UndefValue::get(Caller->getType());
Chris Lattner970c33a2003-06-19 17:00:31 +00008279 }
8280 }
8281
8282 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
8283 Caller->replaceAllUsesWith(NV);
Chris Lattner51f54572007-03-02 19:59:19 +00008284 Caller->eraseFromParent();
Chris Lattnerb15e2b12007-03-02 21:28:56 +00008285 RemoveFromWorkList(Caller);
Chris Lattner970c33a2003-06-19 17:00:31 +00008286 return true;
8287}
8288
Chris Lattnercadac0c2006-11-01 04:51:18 +00008289/// FoldPHIArgBinOpIntoPHI - If we have something like phi [add (a,b), add(c,d)]
8290/// and if a/b/c/d and the add's all have a single use, turn this into two phi's
8291/// and a single binop.
8292Instruction *InstCombiner::FoldPHIArgBinOpIntoPHI(PHINode &PN) {
8293 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
Reid Spencer2341c222007-02-02 02:16:23 +00008294 assert(isa<BinaryOperator>(FirstInst) || isa<GetElementPtrInst>(FirstInst) ||
8295 isa<CmpInst>(FirstInst));
Chris Lattnercadac0c2006-11-01 04:51:18 +00008296 unsigned Opc = FirstInst->getOpcode();
Chris Lattnercd62f112006-11-08 19:29:23 +00008297 Value *LHSVal = FirstInst->getOperand(0);
8298 Value *RHSVal = FirstInst->getOperand(1);
8299
8300 const Type *LHSType = LHSVal->getType();
8301 const Type *RHSType = RHSVal->getType();
Chris Lattnercadac0c2006-11-01 04:51:18 +00008302
8303 // Scan to see if all operands are the same opcode, all have one use, and all
8304 // kill their operands (i.e. the operands have one use).
Chris Lattnerdc826fc2006-11-01 04:55:47 +00008305 for (unsigned i = 0; i != PN.getNumIncomingValues(); ++i) {
Chris Lattnercadac0c2006-11-01 04:51:18 +00008306 Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i));
Chris Lattnerdc826fc2006-11-01 04:55:47 +00008307 if (!I || I->getOpcode() != Opc || !I->hasOneUse() ||
Reid Spencer266e42b2006-12-23 06:05:41 +00008308 // Verify type of the LHS matches so we don't fold cmp's of different
Chris Lattnereebea432006-11-01 07:43:41 +00008309 // types or GEP's with different index types.
8310 I->getOperand(0)->getType() != LHSType ||
8311 I->getOperand(1)->getType() != RHSType)
Chris Lattnercadac0c2006-11-01 04:51:18 +00008312 return 0;
Reid Spencer266e42b2006-12-23 06:05:41 +00008313
8314 // If they are CmpInst instructions, check their predicates
8315 if (Opc == Instruction::ICmp || Opc == Instruction::FCmp)
8316 if (cast<CmpInst>(I)->getPredicate() !=
8317 cast<CmpInst>(FirstInst)->getPredicate())
8318 return 0;
Chris Lattnercd62f112006-11-08 19:29:23 +00008319
8320 // Keep track of which operand needs a phi node.
8321 if (I->getOperand(0) != LHSVal) LHSVal = 0;
8322 if (I->getOperand(1) != RHSVal) RHSVal = 0;
Chris Lattnercadac0c2006-11-01 04:51:18 +00008323 }
8324
Chris Lattner4f218d52006-11-08 19:42:28 +00008325 // Otherwise, this is safe to transform, determine if it is profitable.
8326
8327 // If this is a GEP, and if the index (not the pointer) needs a PHI, bail out.
8328 // Indexes are often folded into load/store instructions, so we don't want to
8329 // hide them behind a phi.
8330 if (isa<GetElementPtrInst>(FirstInst) && RHSVal == 0)
8331 return 0;
8332
Chris Lattnercadac0c2006-11-01 04:51:18 +00008333 Value *InLHS = FirstInst->getOperand(0);
Chris Lattnercadac0c2006-11-01 04:51:18 +00008334 Value *InRHS = FirstInst->getOperand(1);
Chris Lattner4f218d52006-11-08 19:42:28 +00008335 PHINode *NewLHS = 0, *NewRHS = 0;
Chris Lattnercd62f112006-11-08 19:29:23 +00008336 if (LHSVal == 0) {
8337 NewLHS = new PHINode(LHSType, FirstInst->getOperand(0)->getName()+".pn");
8338 NewLHS->reserveOperandSpace(PN.getNumOperands()/2);
8339 NewLHS->addIncoming(InLHS, PN.getIncomingBlock(0));
Chris Lattnereebea432006-11-01 07:43:41 +00008340 InsertNewInstBefore(NewLHS, PN);
8341 LHSVal = NewLHS;
8342 }
Chris Lattnercd62f112006-11-08 19:29:23 +00008343
8344 if (RHSVal == 0) {
8345 NewRHS = new PHINode(RHSType, FirstInst->getOperand(1)->getName()+".pn");
8346 NewRHS->reserveOperandSpace(PN.getNumOperands()/2);
8347 NewRHS->addIncoming(InRHS, PN.getIncomingBlock(0));
Chris Lattnereebea432006-11-01 07:43:41 +00008348 InsertNewInstBefore(NewRHS, PN);
8349 RHSVal = NewRHS;
8350 }
8351
Chris Lattnercd62f112006-11-08 19:29:23 +00008352 // Add all operands to the new PHIs.
8353 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
8354 if (NewLHS) {
8355 Value *NewInLHS =cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
8356 NewLHS->addIncoming(NewInLHS, PN.getIncomingBlock(i));
8357 }
8358 if (NewRHS) {
8359 Value *NewInRHS =cast<Instruction>(PN.getIncomingValue(i))->getOperand(1);
8360 NewRHS->addIncoming(NewInRHS, PN.getIncomingBlock(i));
8361 }
8362 }
8363
Chris Lattnercadac0c2006-11-01 04:51:18 +00008364 if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
Chris Lattnereebea432006-11-01 07:43:41 +00008365 return BinaryOperator::create(BinOp->getOpcode(), LHSVal, RHSVal);
Reid Spencer266e42b2006-12-23 06:05:41 +00008366 else if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst))
8367 return CmpInst::create(CIOp->getOpcode(), CIOp->getPredicate(), LHSVal,
8368 RHSVal);
Chris Lattnereebea432006-11-01 07:43:41 +00008369 else {
8370 assert(isa<GetElementPtrInst>(FirstInst));
8371 return new GetElementPtrInst(LHSVal, RHSVal);
8372 }
Chris Lattnercadac0c2006-11-01 04:51:18 +00008373}
8374
Chris Lattner14f82c72006-11-01 07:13:54 +00008375/// isSafeToSinkLoad - Return true if we know that it is safe sink the load out
8376/// of the block that defines it. This means that it must be obvious the value
8377/// of the load is not changed from the point of the load to the end of the
8378/// block it is in.
Chris Lattnerc9042052007-02-01 22:30:07 +00008379///
8380/// Finally, it is safe, but not profitable, to sink a load targetting a
8381/// non-address-taken alloca. Doing so will cause us to not promote the alloca
8382/// to a register.
Chris Lattner14f82c72006-11-01 07:13:54 +00008383static bool isSafeToSinkLoad(LoadInst *L) {
8384 BasicBlock::iterator BBI = L, E = L->getParent()->end();
8385
8386 for (++BBI; BBI != E; ++BBI)
8387 if (BBI->mayWriteToMemory())
8388 return false;
Chris Lattnerc9042052007-02-01 22:30:07 +00008389
8390 // Check for non-address taken alloca. If not address-taken already, it isn't
8391 // profitable to do this xform.
8392 if (AllocaInst *AI = dyn_cast<AllocaInst>(L->getOperand(0))) {
8393 bool isAddressTaken = false;
8394 for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
8395 UI != E; ++UI) {
8396 if (isa<LoadInst>(UI)) continue;
8397 if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
8398 // If storing TO the alloca, then the address isn't taken.
8399 if (SI->getOperand(1) == AI) continue;
8400 }
8401 isAddressTaken = true;
8402 break;
8403 }
8404
8405 if (!isAddressTaken)
8406 return false;
8407 }
8408
Chris Lattner14f82c72006-11-01 07:13:54 +00008409 return true;
8410}
8411
Chris Lattner970c33a2003-06-19 17:00:31 +00008412
Chris Lattner7515cab2004-11-14 19:13:23 +00008413// FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
8414// operator and they all are only used by the PHI, PHI together their
8415// inputs, and do the operation once, to the result of the PHI.
8416Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
8417 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
8418
8419 // Scan the instruction, looking for input operations that can be folded away.
8420 // If all input operands to the phi are the same instruction (e.g. a cast from
8421 // the same type or "+42") we can pull the operation through the PHI, reducing
8422 // code size and simplifying code.
8423 Constant *ConstantOp = 0;
8424 const Type *CastSrcTy = 0;
Chris Lattner14f82c72006-11-01 07:13:54 +00008425 bool isVolatile = false;
Chris Lattner7515cab2004-11-14 19:13:23 +00008426 if (isa<CastInst>(FirstInst)) {
8427 CastSrcTy = FirstInst->getOperand(0)->getType();
Reid Spencer2341c222007-02-02 02:16:23 +00008428 } else if (isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst)) {
Reid Spencer266e42b2006-12-23 06:05:41 +00008429 // Can fold binop, compare or shift here if the RHS is a constant,
8430 // otherwise call FoldPHIArgBinOpIntoPHI.
Chris Lattner7515cab2004-11-14 19:13:23 +00008431 ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
Chris Lattnercadac0c2006-11-01 04:51:18 +00008432 if (ConstantOp == 0)
8433 return FoldPHIArgBinOpIntoPHI(PN);
Chris Lattner14f82c72006-11-01 07:13:54 +00008434 } else if (LoadInst *LI = dyn_cast<LoadInst>(FirstInst)) {
8435 isVolatile = LI->isVolatile();
8436 // We can't sink the load if the loaded value could be modified between the
8437 // load and the PHI.
8438 if (LI->getParent() != PN.getIncomingBlock(0) ||
8439 !isSafeToSinkLoad(LI))
8440 return 0;
Chris Lattnereebea432006-11-01 07:43:41 +00008441 } else if (isa<GetElementPtrInst>(FirstInst)) {
Chris Lattner4f218d52006-11-08 19:42:28 +00008442 if (FirstInst->getNumOperands() == 2)
Chris Lattnereebea432006-11-01 07:43:41 +00008443 return FoldPHIArgBinOpIntoPHI(PN);
8444 // Can't handle general GEPs yet.
8445 return 0;
Chris Lattner7515cab2004-11-14 19:13:23 +00008446 } else {
8447 return 0; // Cannot fold this operation.
8448 }
8449
8450 // Check to see if all arguments are the same operation.
8451 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
8452 if (!isa<Instruction>(PN.getIncomingValue(i))) return 0;
8453 Instruction *I = cast<Instruction>(PN.getIncomingValue(i));
Reid Spencer266e42b2006-12-23 06:05:41 +00008454 if (!I->hasOneUse() || !I->isSameOperationAs(FirstInst))
Chris Lattner7515cab2004-11-14 19:13:23 +00008455 return 0;
8456 if (CastSrcTy) {
8457 if (I->getOperand(0)->getType() != CastSrcTy)
8458 return 0; // Cast operation must match.
Chris Lattner14f82c72006-11-01 07:13:54 +00008459 } else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
Reid Spencer266e42b2006-12-23 06:05:41 +00008460 // We can't sink the load if the loaded value could be modified between
8461 // the load and the PHI.
Chris Lattner14f82c72006-11-01 07:13:54 +00008462 if (LI->isVolatile() != isVolatile ||
8463 LI->getParent() != PN.getIncomingBlock(i) ||
8464 !isSafeToSinkLoad(LI))
8465 return 0;
Chris Lattner7515cab2004-11-14 19:13:23 +00008466 } else if (I->getOperand(1) != ConstantOp) {
8467 return 0;
8468 }
8469 }
8470
8471 // Okay, they are all the same operation. Create a new PHI node of the
8472 // correct type, and PHI together all of the LHS's of the instructions.
8473 PHINode *NewPN = new PHINode(FirstInst->getOperand(0)->getType(),
8474 PN.getName()+".in");
Chris Lattnerd8e20182005-01-29 00:39:08 +00008475 NewPN->reserveOperandSpace(PN.getNumOperands()/2);
Chris Lattner46dd5a62004-11-14 19:29:34 +00008476
8477 Value *InVal = FirstInst->getOperand(0);
8478 NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
Chris Lattner7515cab2004-11-14 19:13:23 +00008479
8480 // Add all operands to the new PHI.
Chris Lattner46dd5a62004-11-14 19:29:34 +00008481 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
8482 Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
8483 if (NewInVal != InVal)
8484 InVal = 0;
8485 NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
8486 }
8487
8488 Value *PhiVal;
8489 if (InVal) {
8490 // The new PHI unions all of the same values together. This is really
8491 // common, so we handle it intelligently here for compile-time speed.
8492 PhiVal = InVal;
8493 delete NewPN;
8494 } else {
8495 InsertNewInstBefore(NewPN, PN);
8496 PhiVal = NewPN;
8497 }
Misha Brukmanb1c93172005-04-21 23:48:37 +00008498
Chris Lattner7515cab2004-11-14 19:13:23 +00008499 // Insert and return the new operation.
Reid Spencer6c38f0b2006-11-27 01:05:10 +00008500 if (CastInst* FirstCI = dyn_cast<CastInst>(FirstInst))
8501 return CastInst::create(FirstCI->getOpcode(), PhiVal, PN.getType());
Reid Spencerde46e482006-11-02 20:25:50 +00008502 else if (isa<LoadInst>(FirstInst))
Chris Lattner14f82c72006-11-01 07:13:54 +00008503 return new LoadInst(PhiVal, "", isVolatile);
Chris Lattner7515cab2004-11-14 19:13:23 +00008504 else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
Chris Lattner46dd5a62004-11-14 19:29:34 +00008505 return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp);
Reid Spencer266e42b2006-12-23 06:05:41 +00008506 else if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst))
8507 return CmpInst::create(CIOp->getOpcode(), CIOp->getPredicate(),
8508 PhiVal, ConstantOp);
Chris Lattner7515cab2004-11-14 19:13:23 +00008509 else
Reid Spencer2341c222007-02-02 02:16:23 +00008510 assert(0 && "Unknown operation");
Jeff Cohenb622c112007-03-05 00:00:42 +00008511 return 0;
Chris Lattner7515cab2004-11-14 19:13:23 +00008512}
Chris Lattner48a44f72002-05-02 17:06:02 +00008513
Chris Lattner71536432005-01-17 05:10:15 +00008514/// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
8515/// that is dead.
8516static bool DeadPHICycle(PHINode *PN, std::set<PHINode*> &PotentiallyDeadPHIs) {
8517 if (PN->use_empty()) return true;
8518 if (!PN->hasOneUse()) return false;
8519
8520 // Remember this node, and if we find the cycle, return.
8521 if (!PotentiallyDeadPHIs.insert(PN).second)
8522 return true;
8523
8524 if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
8525 return DeadPHICycle(PU, PotentiallyDeadPHIs);
Misha Brukmanb1c93172005-04-21 23:48:37 +00008526
Chris Lattner71536432005-01-17 05:10:15 +00008527 return false;
8528}
8529
Chris Lattnerbbbdd852002-05-06 18:06:38 +00008530// PHINode simplification
8531//
Chris Lattner113f4f42002-06-25 16:13:24 +00008532Instruction *InstCombiner::visitPHINode(PHINode &PN) {
Owen Andersonbbf89902006-07-10 22:15:25 +00008533 // If LCSSA is around, don't mess with Phi nodes
Chris Lattner8258b442007-03-04 04:27:24 +00008534 if (MustPreserveLCSSA) return 0;
Owen Andersona6968f82006-07-10 19:03:49 +00008535
Owen Andersonae8aa642006-07-10 22:03:18 +00008536 if (Value *V = PN.hasConstantValue())
8537 return ReplaceInstUsesWith(PN, V);
8538
Owen Andersonae8aa642006-07-10 22:03:18 +00008539 // If all PHI operands are the same operation, pull them through the PHI,
8540 // reducing code size.
8541 if (isa<Instruction>(PN.getIncomingValue(0)) &&
8542 PN.getIncomingValue(0)->hasOneUse())
8543 if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
8544 return Result;
8545
8546 // If this is a trivial cycle in the PHI node graph, remove it. Basically, if
8547 // this PHI only has a single use (a PHI), and if that PHI only has one use (a
8548 // PHI)... break the cycle.
Chris Lattnerc8dcede2007-01-15 07:30:06 +00008549 if (PN.hasOneUse()) {
8550 Instruction *PHIUser = cast<Instruction>(PN.use_back());
8551 if (PHINode *PU = dyn_cast<PHINode>(PHIUser)) {
Owen Andersonae8aa642006-07-10 22:03:18 +00008552 std::set<PHINode*> PotentiallyDeadPHIs;
8553 PotentiallyDeadPHIs.insert(&PN);
8554 if (DeadPHICycle(PU, PotentiallyDeadPHIs))
8555 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
8556 }
Chris Lattnerc8dcede2007-01-15 07:30:06 +00008557
8558 // If this phi has a single use, and if that use just computes a value for
8559 // the next iteration of a loop, delete the phi. This occurs with unused
8560 // induction variables, e.g. "for (int j = 0; ; ++j);". Detecting this
8561 // common case here is good because the only other things that catch this
8562 // are induction variable analysis (sometimes) and ADCE, which is only run
8563 // late.
8564 if (PHIUser->hasOneUse() &&
8565 (isa<BinaryOperator>(PHIUser) || isa<GetElementPtrInst>(PHIUser)) &&
8566 PHIUser->use_back() == &PN) {
8567 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
8568 }
8569 }
Owen Andersonae8aa642006-07-10 22:03:18 +00008570
Chris Lattner91daeb52003-12-19 05:58:40 +00008571 return 0;
Chris Lattnerbbbdd852002-05-06 18:06:38 +00008572}
8573
Reid Spencer13bc5d72006-12-12 09:18:51 +00008574static Value *InsertCastToIntPtrTy(Value *V, const Type *DTy,
8575 Instruction *InsertPoint,
8576 InstCombiner *IC) {
Reid Spencer8f166b02007-01-08 16:32:00 +00008577 unsigned PtrSize = DTy->getPrimitiveSizeInBits();
8578 unsigned VTySize = V->getType()->getPrimitiveSizeInBits();
Reid Spencer13bc5d72006-12-12 09:18:51 +00008579 // We must cast correctly to the pointer type. Ensure that we
8580 // sign extend the integer value if it is smaller as this is
8581 // used for address computation.
8582 Instruction::CastOps opcode =
8583 (VTySize < PtrSize ? Instruction::SExt :
8584 (VTySize == PtrSize ? Instruction::BitCast : Instruction::Trunc));
8585 return IC->InsertCastBefore(opcode, V, DTy, *InsertPoint);
Chris Lattner69193f92004-04-05 01:30:19 +00008586}
8587
Chris Lattner48a44f72002-05-02 17:06:02 +00008588
Chris Lattner113f4f42002-06-25 16:13:24 +00008589Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
Chris Lattner5f667a62004-05-07 22:09:22 +00008590 Value *PtrOp = GEP.getOperand(0);
Chris Lattner471bd762003-05-22 19:07:21 +00008591 // Is it 'getelementptr %P, long 0' or 'getelementptr %P'
Chris Lattner113f4f42002-06-25 16:13:24 +00008592 // If so, eliminate the noop.
Chris Lattner8d0bacb2004-02-22 05:25:17 +00008593 if (GEP.getNumOperands() == 1)
Chris Lattner5f667a62004-05-07 22:09:22 +00008594 return ReplaceInstUsesWith(GEP, PtrOp);
Chris Lattner8d0bacb2004-02-22 05:25:17 +00008595
Chris Lattner81a7a232004-10-16 18:11:37 +00008596 if (isa<UndefValue>(GEP.getOperand(0)))
8597 return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
8598
Chris Lattner8d0bacb2004-02-22 05:25:17 +00008599 bool HasZeroPointerIndex = false;
8600 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
8601 HasZeroPointerIndex = C->isNullValue();
8602
8603 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
Chris Lattner5f667a62004-05-07 22:09:22 +00008604 return ReplaceInstUsesWith(GEP, PtrOp);
Chris Lattner48a44f72002-05-02 17:06:02 +00008605
Chris Lattner69193f92004-04-05 01:30:19 +00008606 // Eliminate unneeded casts for indices.
8607 bool MadeChange = false;
Chris Lattner2b2412d2004-04-07 18:38:20 +00008608 gep_type_iterator GTI = gep_type_begin(GEP);
8609 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI)
8610 if (isa<SequentialType>(*GTI)) {
8611 if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
Chris Lattner27df1db2007-01-15 07:02:54 +00008612 if (CI->getOpcode() == Instruction::ZExt ||
8613 CI->getOpcode() == Instruction::SExt) {
8614 const Type *SrcTy = CI->getOperand(0)->getType();
8615 // We can eliminate a cast from i32 to i64 iff the target
8616 // is a 32-bit pointer target.
8617 if (SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) {
8618 MadeChange = true;
8619 GEP.setOperand(i, CI->getOperand(0));
Chris Lattner69193f92004-04-05 01:30:19 +00008620 }
8621 }
8622 }
Chris Lattner2b2412d2004-04-07 18:38:20 +00008623 // If we are using a wider index than needed for this platform, shrink it
8624 // to what we need. If the incoming value needs a cast instruction,
8625 // insert it. This explicit cast can make subsequent optimizations more
8626 // obvious.
8627 Value *Op = GEP.getOperand(i);
Reid Spencer7a9c62b2007-01-12 07:05:14 +00008628 if (TD->getTypeSize(Op->getType()) > TD->getPointerSize())
Chris Lattner1e9ac1a2004-04-17 18:16:10 +00008629 if (Constant *C = dyn_cast<Constant>(Op)) {
Reid Spencer266e42b2006-12-23 06:05:41 +00008630 GEP.setOperand(i, ConstantExpr::getTrunc(C, TD->getIntPtrType()));
Chris Lattner1e9ac1a2004-04-17 18:16:10 +00008631 MadeChange = true;
8632 } else {
Reid Spencer13bc5d72006-12-12 09:18:51 +00008633 Op = InsertCastBefore(Instruction::Trunc, Op, TD->getIntPtrType(),
8634 GEP);
Chris Lattner2b2412d2004-04-07 18:38:20 +00008635 GEP.setOperand(i, Op);
8636 MadeChange = true;
8637 }
Chris Lattner69193f92004-04-05 01:30:19 +00008638 }
8639 if (MadeChange) return &GEP;
8640
Chris Lattnerae7a0d32002-08-02 19:29:35 +00008641 // Combine Indices - If the source pointer to this getelementptr instruction
8642 // is a getelementptr instruction, combine the indices of the two
8643 // getelementptr instructions into a single instruction.
8644 //
Chris Lattneraf6094f2007-02-15 22:48:32 +00008645 SmallVector<Value*, 8> SrcGEPOperands;
Chris Lattner0798af32005-01-13 20:14:25 +00008646 if (User *Src = dyn_castGetElementPtr(PtrOp))
Chris Lattneraf6094f2007-02-15 22:48:32 +00008647 SrcGEPOperands.append(Src->op_begin(), Src->op_end());
Chris Lattner57c67b02004-03-25 22:59:29 +00008648
8649 if (!SrcGEPOperands.empty()) {
Chris Lattner5f667a62004-05-07 22:09:22 +00008650 // Note that if our source is a gep chain itself that we wait for that
8651 // chain to be resolved before we perform this transformation. This
8652 // avoids us creating a TON of code in some cases.
8653 //
8654 if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
8655 cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
8656 return 0; // Wait until our source is folded to completion.
8657
Chris Lattneraf6094f2007-02-15 22:48:32 +00008658 SmallVector<Value*, 8> Indices;
Chris Lattner5f667a62004-05-07 22:09:22 +00008659
8660 // Find out whether the last index in the source GEP is a sequential idx.
8661 bool EndsWithSequential = false;
8662 for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
8663 E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
Chris Lattner8ec5f882004-05-08 22:41:42 +00008664 EndsWithSequential = !isa<StructType>(*I);
Misha Brukmanb1c93172005-04-21 23:48:37 +00008665
Chris Lattnerae7a0d32002-08-02 19:29:35 +00008666 // Can we combine the two pointer arithmetics offsets?
Chris Lattner5f667a62004-05-07 22:09:22 +00008667 if (EndsWithSequential) {
Chris Lattner235af562003-03-05 22:33:14 +00008668 // Replace: gep (gep %P, long B), long A, ...
8669 // With: T = long A+B; gep %P, T, ...
8670 //
Chris Lattner5f667a62004-05-07 22:09:22 +00008671 Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
Chris Lattner69193f92004-04-05 01:30:19 +00008672 if (SO1 == Constant::getNullValue(SO1->getType())) {
8673 Sum = GO1;
8674 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
8675 Sum = SO1;
8676 } else {
8677 // If they aren't the same type, convert both to an integer of the
8678 // target's pointer size.
8679 if (SO1->getType() != GO1->getType()) {
8680 if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
Reid Spencer13bc5d72006-12-12 09:18:51 +00008681 SO1 = ConstantExpr::getIntegerCast(SO1C, GO1->getType(), true);
Chris Lattner69193f92004-04-05 01:30:19 +00008682 } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
Reid Spencer13bc5d72006-12-12 09:18:51 +00008683 GO1 = ConstantExpr::getIntegerCast(GO1C, SO1->getType(), true);
Chris Lattner69193f92004-04-05 01:30:19 +00008684 } else {
8685 unsigned PS = TD->getPointerSize();
Reid Spencer7a9c62b2007-01-12 07:05:14 +00008686 if (TD->getTypeSize(SO1->getType()) == PS) {
Chris Lattner69193f92004-04-05 01:30:19 +00008687 // Convert GO1 to SO1's type.
Reid Spencer13bc5d72006-12-12 09:18:51 +00008688 GO1 = InsertCastToIntPtrTy(GO1, SO1->getType(), &GEP, this);
Chris Lattner69193f92004-04-05 01:30:19 +00008689
Reid Spencer7a9c62b2007-01-12 07:05:14 +00008690 } else if (TD->getTypeSize(GO1->getType()) == PS) {
Chris Lattner69193f92004-04-05 01:30:19 +00008691 // Convert SO1 to GO1's type.
Reid Spencer13bc5d72006-12-12 09:18:51 +00008692 SO1 = InsertCastToIntPtrTy(SO1, GO1->getType(), &GEP, this);
Chris Lattner69193f92004-04-05 01:30:19 +00008693 } else {
8694 const Type *PT = TD->getIntPtrType();
Reid Spencer13bc5d72006-12-12 09:18:51 +00008695 SO1 = InsertCastToIntPtrTy(SO1, PT, &GEP, this);
8696 GO1 = InsertCastToIntPtrTy(GO1, PT, &GEP, this);
Chris Lattner69193f92004-04-05 01:30:19 +00008697 }
8698 }
8699 }
Chris Lattner5f667a62004-05-07 22:09:22 +00008700 if (isa<Constant>(SO1) && isa<Constant>(GO1))
8701 Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
8702 else {
Chris Lattnerdf20a4d2004-06-10 02:07:29 +00008703 Sum = BinaryOperator::createAdd(SO1, GO1, PtrOp->getName()+".sum");
8704 InsertNewInstBefore(cast<Instruction>(Sum), GEP);
Chris Lattner5f667a62004-05-07 22:09:22 +00008705 }
Chris Lattner69193f92004-04-05 01:30:19 +00008706 }
Chris Lattner5f667a62004-05-07 22:09:22 +00008707
8708 // Recycle the GEP we already have if possible.
8709 if (SrcGEPOperands.size() == 2) {
8710 GEP.setOperand(0, SrcGEPOperands[0]);
8711 GEP.setOperand(1, Sum);
8712 return &GEP;
8713 } else {
8714 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
8715 SrcGEPOperands.end()-1);
8716 Indices.push_back(Sum);
8717 Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
8718 }
Misha Brukmanb1c93172005-04-21 23:48:37 +00008719 } else if (isa<Constant>(*GEP.idx_begin()) &&
Chris Lattner69193f92004-04-05 01:30:19 +00008720 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
Misha Brukmanb1c93172005-04-21 23:48:37 +00008721 SrcGEPOperands.size() != 1) {
Chris Lattnerae7a0d32002-08-02 19:29:35 +00008722 // Otherwise we can do the fold if the first index of the GEP is a zero
Chris Lattner57c67b02004-03-25 22:59:29 +00008723 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
8724 SrcGEPOperands.end());
Chris Lattnerae7a0d32002-08-02 19:29:35 +00008725 Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
8726 }
8727
8728 if (!Indices.empty())
Chris Lattnera7315132007-02-12 22:56:41 +00008729 return new GetElementPtrInst(SrcGEPOperands[0], &Indices[0],
8730 Indices.size(), GEP.getName());
Chris Lattnerc59af1d2002-08-17 22:21:59 +00008731
Chris Lattner5f667a62004-05-07 22:09:22 +00008732 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
Chris Lattnerc59af1d2002-08-17 22:21:59 +00008733 // GEP of global variable. If all of the indices for this GEP are
8734 // constants, we can promote this to a constexpr instead of an instruction.
8735
8736 // Scan for nonconstants...
Chris Lattnerf96f4a82007-01-31 04:40:53 +00008737 SmallVector<Constant*, 8> Indices;
Chris Lattnerc59af1d2002-08-17 22:21:59 +00008738 User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
8739 for (; I != E && isa<Constant>(*I); ++I)
8740 Indices.push_back(cast<Constant>(*I));
8741
8742 if (I == E) { // If they are all constants...
Chris Lattnerf96f4a82007-01-31 04:40:53 +00008743 Constant *CE = ConstantExpr::getGetElementPtr(GV,
8744 &Indices[0],Indices.size());
Chris Lattnerc59af1d2002-08-17 22:21:59 +00008745
8746 // Replace all uses of the GEP with the new constexpr...
8747 return ReplaceInstUsesWith(GEP, CE);
8748 }
Reid Spencer6c38f0b2006-11-27 01:05:10 +00008749 } else if (Value *X = getBitCastOperand(PtrOp)) { // Is the operand a cast?
Chris Lattner567b81f2005-09-13 00:40:14 +00008750 if (!isa<PointerType>(X->getType())) {
8751 // Not interesting. Source pointer must be a cast from pointer.
8752 } else if (HasZeroPointerIndex) {
8753 // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
8754 // into : GEP [10 x ubyte]* X, long 0, ...
8755 //
8756 // This occurs when the program declares an array extern like "int X[];"
8757 //
8758 const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
8759 const PointerType *XTy = cast<PointerType>(X->getType());
8760 if (const ArrayType *XATy =
8761 dyn_cast<ArrayType>(XTy->getElementType()))
8762 if (const ArrayType *CATy =
8763 dyn_cast<ArrayType>(CPTy->getElementType()))
8764 if (CATy->getElementType() == XATy->getElementType()) {
8765 // At this point, we know that the cast source type is a pointer
8766 // to an array of the same type as the destination pointer
8767 // array. Because the array type is never stepped over (there
8768 // is a leading zero) we can fold the cast into this GEP.
8769 GEP.setOperand(0, X);
8770 return &GEP;
8771 }
8772 } else if (GEP.getNumOperands() == 2) {
8773 // Transform things like:
Chris Lattner2a893292005-09-13 18:36:04 +00008774 // %t = getelementptr ubyte* cast ([2 x int]* %str to uint*), uint %V
8775 // into: %t1 = getelementptr [2 x int*]* %str, int 0, uint %V; cast
Chris Lattner567b81f2005-09-13 00:40:14 +00008776 const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
8777 const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
8778 if (isa<ArrayType>(SrcElTy) &&
8779 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
8780 TD->getTypeSize(ResElTy)) {
8781 Value *V = InsertNewInstBefore(
Reid Spencerc635f472006-12-31 05:48:39 +00008782 new GetElementPtrInst(X, Constant::getNullValue(Type::Int32Ty),
Chris Lattner567b81f2005-09-13 00:40:14 +00008783 GEP.getOperand(1), GEP.getName()), GEP);
Reid Spencer6c38f0b2006-11-27 01:05:10 +00008784 // V and GEP are both pointer types --> BitCast
8785 return new BitCastInst(V, GEP.getType());
Chris Lattner8d0bacb2004-02-22 05:25:17 +00008786 }
Chris Lattner2a893292005-09-13 18:36:04 +00008787
8788 // Transform things like:
8789 // getelementptr sbyte* cast ([100 x double]* X to sbyte*), int %tmp
8790 // (where tmp = 8*tmp2) into:
8791 // getelementptr [100 x double]* %arr, int 0, int %tmp.2
8792
8793 if (isa<ArrayType>(SrcElTy) &&
Reid Spencerc635f472006-12-31 05:48:39 +00008794 (ResElTy == Type::Int8Ty || ResElTy == Type::Int8Ty)) {
Chris Lattner2a893292005-09-13 18:36:04 +00008795 uint64_t ArrayEltSize =
8796 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType());
8797
8798 // Check to see if "tmp" is a scale by a multiple of ArrayEltSize. We
8799 // allow either a mul, shift, or constant here.
8800 Value *NewIdx = 0;
8801 ConstantInt *Scale = 0;
8802 if (ArrayEltSize == 1) {
8803 NewIdx = GEP.getOperand(1);
8804 Scale = ConstantInt::get(NewIdx->getType(), 1);
8805 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) {
Chris Lattnera393e4d2005-09-14 17:32:56 +00008806 NewIdx = ConstantInt::get(CI->getType(), 1);
Chris Lattner2a893292005-09-13 18:36:04 +00008807 Scale = CI;
8808 } else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){
8809 if (Inst->getOpcode() == Instruction::Shl &&
8810 isa<ConstantInt>(Inst->getOperand(1))) {
Reid Spencere0fc4df2006-10-20 07:07:24 +00008811 unsigned ShAmt =
8812 cast<ConstantInt>(Inst->getOperand(1))->getZExtValue();
Reid Spencer266e42b2006-12-23 06:05:41 +00008813 Scale = ConstantInt::get(Inst->getType(), 1ULL << ShAmt);
Chris Lattner2a893292005-09-13 18:36:04 +00008814 NewIdx = Inst->getOperand(0);
8815 } else if (Inst->getOpcode() == Instruction::Mul &&
8816 isa<ConstantInt>(Inst->getOperand(1))) {
8817 Scale = cast<ConstantInt>(Inst->getOperand(1));
8818 NewIdx = Inst->getOperand(0);
8819 }
8820 }
8821
8822 // If the index will be to exactly the right offset with the scale taken
8823 // out, perform the transformation.
Reid Spencere0fc4df2006-10-20 07:07:24 +00008824 if (Scale && Scale->getZExtValue() % ArrayEltSize == 0) {
Reid Spencerde46e482006-11-02 20:25:50 +00008825 if (isa<ConstantInt>(Scale))
Reid Spencere0fc4df2006-10-20 07:07:24 +00008826 Scale = ConstantInt::get(Scale->getType(),
8827 Scale->getZExtValue() / ArrayEltSize);
8828 if (Scale->getZExtValue() != 1) {
Reid Spencer13bc5d72006-12-12 09:18:51 +00008829 Constant *C = ConstantExpr::getIntegerCast(Scale, NewIdx->getType(),
8830 true /*SExt*/);
Chris Lattner2a893292005-09-13 18:36:04 +00008831 Instruction *Sc = BinaryOperator::createMul(NewIdx, C, "idxscale");
8832 NewIdx = InsertNewInstBefore(Sc, GEP);
8833 }
8834
8835 // Insert the new GEP instruction.
Reid Spencer6c38f0b2006-11-27 01:05:10 +00008836 Instruction *NewGEP =
Reid Spencerc635f472006-12-31 05:48:39 +00008837 new GetElementPtrInst(X, Constant::getNullValue(Type::Int32Ty),
Chris Lattner2a893292005-09-13 18:36:04 +00008838 NewIdx, GEP.getName());
Reid Spencer6c38f0b2006-11-27 01:05:10 +00008839 NewGEP = InsertNewInstBefore(NewGEP, GEP);
8840 // The NewGEP must be pointer typed, so must the old one -> BitCast
8841 return new BitCastInst(NewGEP, GEP.getType());
Chris Lattner2a893292005-09-13 18:36:04 +00008842 }
8843 }
Chris Lattner8d0bacb2004-02-22 05:25:17 +00008844 }
Chris Lattnerca081252001-12-14 16:52:21 +00008845 }
8846
Chris Lattnerca081252001-12-14 16:52:21 +00008847 return 0;
8848}
8849
Chris Lattner1085bdf2002-11-04 16:18:53 +00008850Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
8851 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
8852 if (AI.isArrayAllocation()) // Check C != 1
Reid Spencere0fc4df2006-10-20 07:07:24 +00008853 if (const ConstantInt *C = dyn_cast<ConstantInt>(AI.getArraySize())) {
8854 const Type *NewTy =
8855 ArrayType::get(AI.getAllocatedType(), C->getZExtValue());
Chris Lattnera2620ac2002-11-09 00:49:43 +00008856 AllocationInst *New = 0;
Chris Lattner1085bdf2002-11-04 16:18:53 +00008857
8858 // Create and insert the replacement instruction...
8859 if (isa<MallocInst>(AI))
Nate Begeman848622f2005-11-05 09:21:28 +00008860 New = new MallocInst(NewTy, 0, AI.getAlignment(), AI.getName());
Chris Lattnera2620ac2002-11-09 00:49:43 +00008861 else {
8862 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
Nate Begeman848622f2005-11-05 09:21:28 +00008863 New = new AllocaInst(NewTy, 0, AI.getAlignment(), AI.getName());
Chris Lattnera2620ac2002-11-09 00:49:43 +00008864 }
Chris Lattnerabb77c92004-03-19 06:08:10 +00008865
8866 InsertNewInstBefore(New, AI);
Misha Brukmanb1c93172005-04-21 23:48:37 +00008867
Chris Lattner1085bdf2002-11-04 16:18:53 +00008868 // Scan to the end of the allocation instructions, to skip over a block of
8869 // allocas if possible...
8870 //
8871 BasicBlock::iterator It = New;
8872 while (isa<AllocationInst>(*It)) ++It;
8873
8874 // Now that I is pointing to the first non-allocation-inst in the block,
8875 // insert our getelementptr instruction...
8876 //
Reid Spencerc635f472006-12-31 05:48:39 +00008877 Value *NullIdx = Constant::getNullValue(Type::Int32Ty);
Chris Lattner809dfac2005-05-04 19:10:26 +00008878 Value *V = new GetElementPtrInst(New, NullIdx, NullIdx,
8879 New->getName()+".sub", It);
Chris Lattner1085bdf2002-11-04 16:18:53 +00008880
8881 // Now make everything use the getelementptr instead of the original
8882 // allocation.
Chris Lattnerabb77c92004-03-19 06:08:10 +00008883 return ReplaceInstUsesWith(AI, V);
Chris Lattner81a7a232004-10-16 18:11:37 +00008884 } else if (isa<UndefValue>(AI.getArraySize())) {
8885 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
Chris Lattner1085bdf2002-11-04 16:18:53 +00008886 }
Chris Lattnerabb77c92004-03-19 06:08:10 +00008887
8888 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
8889 // Note that we only do this for alloca's, because malloc should allocate and
8890 // return a unique pointer, even for a zero byte allocation.
Misha Brukmanb1c93172005-04-21 23:48:37 +00008891 if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() &&
Chris Lattner49df6ce2004-07-02 22:55:47 +00008892 TD->getTypeSize(AI.getAllocatedType()) == 0)
Chris Lattnerabb77c92004-03-19 06:08:10 +00008893 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
8894
Chris Lattner1085bdf2002-11-04 16:18:53 +00008895 return 0;
8896}
8897
Chris Lattner8427bff2003-12-07 01:24:23 +00008898Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
8899 Value *Op = FI.getOperand(0);
8900
8901 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
8902 if (CastInst *CI = dyn_cast<CastInst>(Op))
8903 if (isa<PointerType>(CI->getOperand(0)->getType())) {
8904 FI.setOperand(0, CI->getOperand(0));
8905 return &FI;
8906 }
8907
Chris Lattner8ba9ec92004-10-18 02:59:09 +00008908 // free undef -> unreachable.
8909 if (isa<UndefValue>(Op)) {
8910 // Insert a new store to null because we cannot modify the CFG here.
Zhou Sheng75b871f2007-01-11 12:24:14 +00008911 new StoreInst(ConstantInt::getTrue(),
Reid Spencer542964f2007-01-11 18:21:29 +00008912 UndefValue::get(PointerType::get(Type::Int1Ty)), &FI);
Chris Lattner8ba9ec92004-10-18 02:59:09 +00008913 return EraseInstFromFunction(FI);
8914 }
8915
Chris Lattnerf3a36602004-02-28 04:57:37 +00008916 // If we have 'free null' delete the instruction. This can happen in stl code
8917 // when lots of inlining happens.
Chris Lattner8ba9ec92004-10-18 02:59:09 +00008918 if (isa<ConstantPointerNull>(Op))
Chris Lattner51ea1272004-02-28 05:22:00 +00008919 return EraseInstFromFunction(FI);
Chris Lattnerf3a36602004-02-28 04:57:37 +00008920
Chris Lattner8427bff2003-12-07 01:24:23 +00008921 return 0;
8922}
8923
8924
Chris Lattner72684fe2005-01-31 05:51:45 +00008925/// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
Chris Lattner35e24772004-07-13 01:49:43 +00008926static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
8927 User *CI = cast<User>(LI.getOperand(0));
Chris Lattnerfe1b0b82005-01-31 04:50:46 +00008928 Value *CastOp = CI->getOperand(0);
Chris Lattner35e24772004-07-13 01:49:43 +00008929
8930 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
Chris Lattnerfe1b0b82005-01-31 04:50:46 +00008931 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
Chris Lattner35e24772004-07-13 01:49:43 +00008932 const Type *SrcPTy = SrcTy->getElementType();
Chris Lattnerfe1b0b82005-01-31 04:50:46 +00008933
Reid Spencer31a4ef42007-01-22 05:51:25 +00008934 if (DestPTy->isInteger() || isa<PointerType>(DestPTy) ||
Reid Spencerd84d35b2007-02-15 02:26:10 +00008935 isa<VectorType>(DestPTy)) {
Chris Lattnerfe1b0b82005-01-31 04:50:46 +00008936 // If the source is an array, the code below will not succeed. Check to
8937 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
8938 // constants.
8939 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
8940 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
8941 if (ASrcTy->getNumElements() != 0) {
Chris Lattnerf96f4a82007-01-31 04:40:53 +00008942 Value *Idxs[2];
8943 Idxs[0] = Idxs[1] = Constant::getNullValue(Type::Int32Ty);
8944 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs, 2);
Chris Lattnerfe1b0b82005-01-31 04:50:46 +00008945 SrcTy = cast<PointerType>(CastOp->getType());
8946 SrcPTy = SrcTy->getElementType();
8947 }
8948
Reid Spencer31a4ef42007-01-22 05:51:25 +00008949 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy) ||
Reid Spencerd84d35b2007-02-15 02:26:10 +00008950 isa<VectorType>(SrcPTy)) &&
Chris Lattnerecfa9b52005-03-29 06:37:47 +00008951 // Do not allow turning this into a load of an integer, which is then
8952 // casted to a pointer, this pessimizes pointer analysis a lot.
8953 (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
Reid Spencer31a4ef42007-01-22 05:51:25 +00008954 IC.getTargetData().getTypeSizeInBits(SrcPTy) ==
8955 IC.getTargetData().getTypeSizeInBits(DestPTy)) {
Misha Brukmanb1c93172005-04-21 23:48:37 +00008956
Chris Lattnerfe1b0b82005-01-31 04:50:46 +00008957 // Okay, we are casting from one integer or pointer type to another of
8958 // the same size. Instead of casting the pointer before the load, cast
8959 // the result of the loaded value.
8960 Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CastOp,
8961 CI->getName(),
8962 LI.isVolatile()),LI);
8963 // Now cast the result of the load.
Reid Spencerbb65ebf2006-12-12 23:36:14 +00008964 return new BitCastInst(NewLoad, LI.getType());
Chris Lattnerfe1b0b82005-01-31 04:50:46 +00008965 }
Chris Lattner35e24772004-07-13 01:49:43 +00008966 }
8967 }
8968 return 0;
8969}
8970
Chris Lattnerf62ea8e2004-09-19 18:43:46 +00008971/// isSafeToLoadUnconditionally - Return true if we know that executing a load
Chris Lattnere6f13092004-09-19 19:18:10 +00008972/// from this value cannot trap. If it is not obviously safe to load from the
8973/// specified pointer, we do a quick local scan of the basic block containing
8974/// ScanFrom, to determine if the address is already accessed.
8975static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
8976 // If it is an alloca or global variable, it is always safe to load from.
8977 if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true;
8978
8979 // Otherwise, be a little bit agressive by scanning the local block where we
8980 // want to check to see if the pointer is already being loaded or stored
Alkis Evlogimenosd59cebf2004-09-20 06:42:58 +00008981 // from/to. If so, the previous load or store would have already trapped,
8982 // so there is no harm doing an extra load (also, CSE will later eliminate
8983 // the load entirely).
Chris Lattnere6f13092004-09-19 19:18:10 +00008984 BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
8985
Alkis Evlogimenosd59cebf2004-09-20 06:42:58 +00008986 while (BBI != E) {
Chris Lattnere6f13092004-09-19 19:18:10 +00008987 --BBI;
8988
8989 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
8990 if (LI->getOperand(0) == V) return true;
8991 } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
8992 if (SI->getOperand(1) == V) return true;
Misha Brukmanb1c93172005-04-21 23:48:37 +00008993
Alkis Evlogimenosd59cebf2004-09-20 06:42:58 +00008994 }
Chris Lattnere6f13092004-09-19 19:18:10 +00008995 return false;
Chris Lattnerf62ea8e2004-09-19 18:43:46 +00008996}
8997
Chris Lattner0f1d8a32003-06-26 05:06:25 +00008998Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
8999 Value *Op = LI.getOperand(0);
Chris Lattner7e8af382004-01-12 04:13:56 +00009000
Chris Lattnera9d84e32005-05-01 04:24:53 +00009001 // load (cast X) --> cast (load X) iff safe
Reid Spencerde46e482006-11-02 20:25:50 +00009002 if (isa<CastInst>(Op))
Chris Lattnera9d84e32005-05-01 04:24:53 +00009003 if (Instruction *Res = InstCombineLoadCast(*this, LI))
9004 return Res;
9005
9006 // None of the following transforms are legal for volatile loads.
9007 if (LI.isVolatile()) return 0;
Chris Lattnerb990f7d2005-09-12 22:00:15 +00009008
Chris Lattnerb990f7d2005-09-12 22:00:15 +00009009 if (&LI.getParent()->front() != &LI) {
9010 BasicBlock::iterator BBI = &LI; --BBI;
Chris Lattnere0bfdf12005-09-12 22:21:03 +00009011 // If the instruction immediately before this is a store to the same
9012 // address, do a simple form of store->load forwarding.
Chris Lattnerb990f7d2005-09-12 22:00:15 +00009013 if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
9014 if (SI->getOperand(1) == LI.getOperand(0))
9015 return ReplaceInstUsesWith(LI, SI->getOperand(0));
Chris Lattnere0bfdf12005-09-12 22:21:03 +00009016 if (LoadInst *LIB = dyn_cast<LoadInst>(BBI))
9017 if (LIB->getOperand(0) == LI.getOperand(0))
9018 return ReplaceInstUsesWith(LI, LIB);
Chris Lattnerb990f7d2005-09-12 22:00:15 +00009019 }
Chris Lattnera9d84e32005-05-01 04:24:53 +00009020
9021 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op))
9022 if (isa<ConstantPointerNull>(GEPI->getOperand(0)) ||
9023 isa<UndefValue>(GEPI->getOperand(0))) {
9024 // Insert a new store to null instruction before the load to indicate
9025 // that this code is not reachable. We do this instead of inserting
9026 // an unreachable instruction directly because we cannot modify the
9027 // CFG.
9028 new StoreInst(UndefValue::get(LI.getType()),
9029 Constant::getNullValue(Op->getType()), &LI);
9030 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
9031 }
9032
Chris Lattner81a7a232004-10-16 18:11:37 +00009033 if (Constant *C = dyn_cast<Constant>(Op)) {
Chris Lattnera9d84e32005-05-01 04:24:53 +00009034 // load null/undef -> undef
9035 if ((C->isNullValue() || isa<UndefValue>(C))) {
Chris Lattner8ba9ec92004-10-18 02:59:09 +00009036 // Insert a new store to null instruction before the load to indicate that
9037 // this code is not reachable. We do this instead of inserting an
9038 // unreachable instruction directly because we cannot modify the CFG.
Chris Lattnera9d84e32005-05-01 04:24:53 +00009039 new StoreInst(UndefValue::get(LI.getType()),
9040 Constant::getNullValue(Op->getType()), &LI);
Chris Lattner81a7a232004-10-16 18:11:37 +00009041 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
Chris Lattner8ba9ec92004-10-18 02:59:09 +00009042 }
Chris Lattner0f1d8a32003-06-26 05:06:25 +00009043
Chris Lattner81a7a232004-10-16 18:11:37 +00009044 // Instcombine load (constant global) into the value loaded.
9045 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
Reid Spencer5301e7c2007-01-30 20:08:39 +00009046 if (GV->isConstant() && !GV->isDeclaration())
Chris Lattner81a7a232004-10-16 18:11:37 +00009047 return ReplaceInstUsesWith(LI, GV->getInitializer());
Misha Brukmanb1c93172005-04-21 23:48:37 +00009048
Chris Lattner81a7a232004-10-16 18:11:37 +00009049 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
9050 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
9051 if (CE->getOpcode() == Instruction::GetElementPtr) {
9052 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
Reid Spencer5301e7c2007-01-30 20:08:39 +00009053 if (GV->isConstant() && !GV->isDeclaration())
Chris Lattner0b011ec2005-09-26 05:28:06 +00009054 if (Constant *V =
9055 ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
Chris Lattner81a7a232004-10-16 18:11:37 +00009056 return ReplaceInstUsesWith(LI, V);
Chris Lattnera9d84e32005-05-01 04:24:53 +00009057 if (CE->getOperand(0)->isNullValue()) {
9058 // Insert a new store to null instruction before the load to indicate
9059 // that this code is not reachable. We do this instead of inserting
9060 // an unreachable instruction directly because we cannot modify the
9061 // CFG.
9062 new StoreInst(UndefValue::get(LI.getType()),
9063 Constant::getNullValue(Op->getType()), &LI);
9064 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
9065 }
9066
Reid Spencer6c38f0b2006-11-27 01:05:10 +00009067 } else if (CE->isCast()) {
Chris Lattner81a7a232004-10-16 18:11:37 +00009068 if (Instruction *Res = InstCombineLoadCast(*this, LI))
9069 return Res;
9070 }
9071 }
Chris Lattnere228ee52004-04-08 20:39:49 +00009072
Chris Lattnera9d84e32005-05-01 04:24:53 +00009073 if (Op->hasOneUse()) {
Chris Lattnerf62ea8e2004-09-19 18:43:46 +00009074 // Change select and PHI nodes to select values instead of addresses: this
9075 // helps alias analysis out a lot, allows many others simplifications, and
9076 // exposes redundancy in the code.
9077 //
9078 // Note that we cannot do the transformation unless we know that the
9079 // introduced loads cannot trap! Something like this is valid as long as
9080 // the condition is always false: load (select bool %C, int* null, int* %G),
9081 // but it would not be valid if we transformed it to load from null
9082 // unconditionally.
9083 //
9084 if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
9085 // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
Chris Lattnere6f13092004-09-19 19:18:10 +00009086 if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
9087 isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
Chris Lattnerf62ea8e2004-09-19 18:43:46 +00009088 Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
Chris Lattner42618552004-09-20 10:15:10 +00009089 SI->getOperand(1)->getName()+".val"), LI);
Chris Lattnerf62ea8e2004-09-19 18:43:46 +00009090 Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
Chris Lattner42618552004-09-20 10:15:10 +00009091 SI->getOperand(2)->getName()+".val"), LI);
Chris Lattnerf62ea8e2004-09-19 18:43:46 +00009092 return new SelectInst(SI->getCondition(), V1, V2);
9093 }
9094
Chris Lattnerbdcf41a2004-09-23 15:46:00 +00009095 // load (select (cond, null, P)) -> load P
9096 if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
9097 if (C->isNullValue()) {
9098 LI.setOperand(0, SI->getOperand(2));
9099 return &LI;
9100 }
9101
9102 // load (select (cond, P, null)) -> load P
9103 if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
9104 if (C->isNullValue()) {
9105 LI.setOperand(0, SI->getOperand(1));
9106 return &LI;
9107 }
Chris Lattnerf62ea8e2004-09-19 18:43:46 +00009108 }
9109 }
Chris Lattner0f1d8a32003-06-26 05:06:25 +00009110 return 0;
9111}
9112
Reid Spencere928a152007-01-19 21:20:31 +00009113/// InstCombineStoreToCast - Fold store V, (cast P) -> store (cast V), P
Chris Lattner72684fe2005-01-31 05:51:45 +00009114/// when possible.
9115static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
9116 User *CI = cast<User>(SI.getOperand(1));
9117 Value *CastOp = CI->getOperand(0);
9118
9119 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
9120 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
9121 const Type *SrcPTy = SrcTy->getElementType();
9122
Reid Spencer31a4ef42007-01-22 05:51:25 +00009123 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
Chris Lattner72684fe2005-01-31 05:51:45 +00009124 // If the source is an array, the code below will not succeed. Check to
9125 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
9126 // constants.
9127 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
9128 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
9129 if (ASrcTy->getNumElements() != 0) {
Chris Lattnerf96f4a82007-01-31 04:40:53 +00009130 Value* Idxs[2];
9131 Idxs[0] = Idxs[1] = Constant::getNullValue(Type::Int32Ty);
9132 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs, 2);
Chris Lattner72684fe2005-01-31 05:51:45 +00009133 SrcTy = cast<PointerType>(CastOp->getType());
9134 SrcPTy = SrcTy->getElementType();
9135 }
9136
Reid Spencer9a4bed02007-01-20 23:35:48 +00009137 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
9138 IC.getTargetData().getTypeSizeInBits(SrcPTy) ==
9139 IC.getTargetData().getTypeSizeInBits(DestPTy)) {
Chris Lattner72684fe2005-01-31 05:51:45 +00009140
9141 // Okay, we are casting from one integer or pointer type to another of
Reid Spencerc050af92007-01-18 18:54:33 +00009142 // the same size. Instead of casting the pointer before
9143 // the store, cast the value to be stored.
Chris Lattner72684fe2005-01-31 05:51:45 +00009144 Value *NewCast;
Reid Spencerbb65ebf2006-12-12 23:36:14 +00009145 Value *SIOp0 = SI.getOperand(0);
Reid Spencerc050af92007-01-18 18:54:33 +00009146 Instruction::CastOps opcode = Instruction::BitCast;
9147 const Type* CastSrcTy = SIOp0->getType();
9148 const Type* CastDstTy = SrcPTy;
9149 if (isa<PointerType>(CastDstTy)) {
9150 if (CastSrcTy->isInteger())
Reid Spencerbb65ebf2006-12-12 23:36:14 +00009151 opcode = Instruction::IntToPtr;
Reid Spencer9a4bed02007-01-20 23:35:48 +00009152 } else if (isa<IntegerType>(CastDstTy)) {
Reid Spencer74a528b2006-12-13 18:21:21 +00009153 if (isa<PointerType>(SIOp0->getType()))
Reid Spencerbb65ebf2006-12-12 23:36:14 +00009154 opcode = Instruction::PtrToInt;
9155 }
9156 if (Constant *C = dyn_cast<Constant>(SIOp0))
Reid Spencerc050af92007-01-18 18:54:33 +00009157 NewCast = ConstantExpr::getCast(opcode, C, CastDstTy);
Chris Lattner72684fe2005-01-31 05:51:45 +00009158 else
Reid Spencer6c38f0b2006-11-27 01:05:10 +00009159 NewCast = IC.InsertNewInstBefore(
Reid Spencerc050af92007-01-18 18:54:33 +00009160 CastInst::create(opcode, SIOp0, CastDstTy, SIOp0->getName()+".c"),
9161 SI);
Chris Lattner72684fe2005-01-31 05:51:45 +00009162 return new StoreInst(NewCast, CastOp);
9163 }
9164 }
9165 }
9166 return 0;
9167}
9168
Chris Lattner31f486c2005-01-31 05:36:43 +00009169Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
9170 Value *Val = SI.getOperand(0);
9171 Value *Ptr = SI.getOperand(1);
9172
9173 if (isa<UndefValue>(Ptr)) { // store X, undef -> noop (even if volatile)
Chris Lattner5997cf92006-02-08 03:25:32 +00009174 EraseInstFromFunction(SI);
Chris Lattner31f486c2005-01-31 05:36:43 +00009175 ++NumCombined;
9176 return 0;
9177 }
Chris Lattnera4beeef2007-01-15 06:51:56 +00009178
9179 // If the RHS is an alloca with a single use, zapify the store, making the
9180 // alloca dead.
9181 if (Ptr->hasOneUse()) {
9182 if (isa<AllocaInst>(Ptr)) {
9183 EraseInstFromFunction(SI);
9184 ++NumCombined;
9185 return 0;
9186 }
9187
9188 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr))
9189 if (isa<AllocaInst>(GEP->getOperand(0)) &&
9190 GEP->getOperand(0)->hasOneUse()) {
9191 EraseInstFromFunction(SI);
9192 ++NumCombined;
9193 return 0;
9194 }
9195 }
Chris Lattner31f486c2005-01-31 05:36:43 +00009196
Chris Lattner5997cf92006-02-08 03:25:32 +00009197 // Do really simple DSE, to catch cases where there are several consequtive
9198 // stores to the same location, separated by a few arithmetic operations. This
9199 // situation often occurs with bitfield accesses.
9200 BasicBlock::iterator BBI = &SI;
9201 for (unsigned ScanInsts = 6; BBI != SI.getParent()->begin() && ScanInsts;
9202 --ScanInsts) {
9203 --BBI;
9204
9205 if (StoreInst *PrevSI = dyn_cast<StoreInst>(BBI)) {
9206 // Prev store isn't volatile, and stores to the same location?
9207 if (!PrevSI->isVolatile() && PrevSI->getOperand(1) == SI.getOperand(1)) {
9208 ++NumDeadStore;
9209 ++BBI;
9210 EraseInstFromFunction(*PrevSI);
9211 continue;
9212 }
9213 break;
9214 }
9215
Chris Lattnerdab43b22006-05-26 19:19:20 +00009216 // If this is a load, we have to stop. However, if the loaded value is from
9217 // the pointer we're loading and is producing the pointer we're storing,
9218 // then *this* store is dead (X = load P; store X -> P).
9219 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
9220 if (LI == Val && LI->getOperand(0) == Ptr) {
9221 EraseInstFromFunction(SI);
9222 ++NumCombined;
9223 return 0;
9224 }
9225 // Otherwise, this is a load from some other location. Stores before it
9226 // may not be dead.
9227 break;
9228 }
9229
Chris Lattner5997cf92006-02-08 03:25:32 +00009230 // Don't skip over loads or things that can modify memory.
Chris Lattnerdab43b22006-05-26 19:19:20 +00009231 if (BBI->mayWriteToMemory())
Chris Lattner5997cf92006-02-08 03:25:32 +00009232 break;
9233 }
9234
9235
9236 if (SI.isVolatile()) return 0; // Don't hack volatile stores.
Chris Lattner31f486c2005-01-31 05:36:43 +00009237
9238 // store X, null -> turns into 'unreachable' in SimplifyCFG
9239 if (isa<ConstantPointerNull>(Ptr)) {
9240 if (!isa<UndefValue>(Val)) {
9241 SI.setOperand(0, UndefValue::get(Val->getType()));
9242 if (Instruction *U = dyn_cast<Instruction>(Val))
Chris Lattnerb15e2b12007-03-02 21:28:56 +00009243 AddToWorkList(U); // Dropped a use.
Chris Lattner31f486c2005-01-31 05:36:43 +00009244 ++NumCombined;
9245 }
9246 return 0; // Do not modify these!
9247 }
9248
9249 // store undef, Ptr -> noop
9250 if (isa<UndefValue>(Val)) {
Chris Lattner5997cf92006-02-08 03:25:32 +00009251 EraseInstFromFunction(SI);
Chris Lattner31f486c2005-01-31 05:36:43 +00009252 ++NumCombined;
9253 return 0;
9254 }
9255
Chris Lattner72684fe2005-01-31 05:51:45 +00009256 // If the pointer destination is a cast, see if we can fold the cast into the
9257 // source instead.
Reid Spencerde46e482006-11-02 20:25:50 +00009258 if (isa<CastInst>(Ptr))
Chris Lattner72684fe2005-01-31 05:51:45 +00009259 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
9260 return Res;
9261 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
Reid Spencer6c38f0b2006-11-27 01:05:10 +00009262 if (CE->isCast())
Chris Lattner72684fe2005-01-31 05:51:45 +00009263 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
9264 return Res;
9265
Chris Lattner219175c2005-09-12 23:23:25 +00009266
9267 // If this store is the last instruction in the basic block, and if the block
9268 // ends with an unconditional branch, try to move it to the successor block.
Chris Lattner5997cf92006-02-08 03:25:32 +00009269 BBI = &SI; ++BBI;
Chris Lattner219175c2005-09-12 23:23:25 +00009270 if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
9271 if (BI->isUnconditional()) {
9272 // Check to see if the successor block has exactly two incoming edges. If
9273 // so, see if the other predecessor contains a store to the same location.
9274 // if so, insert a PHI node (if needed) and move the stores down.
9275 BasicBlock *Dest = BI->getSuccessor(0);
9276
9277 pred_iterator PI = pred_begin(Dest);
9278 BasicBlock *Other = 0;
9279 if (*PI != BI->getParent())
9280 Other = *PI;
9281 ++PI;
9282 if (PI != pred_end(Dest)) {
9283 if (*PI != BI->getParent())
9284 if (Other)
9285 Other = 0;
9286 else
9287 Other = *PI;
9288 if (++PI != pred_end(Dest))
9289 Other = 0;
9290 }
9291 if (Other) { // If only one other pred...
9292 BBI = Other->getTerminator();
9293 // Make sure this other block ends in an unconditional branch and that
9294 // there is an instruction before the branch.
9295 if (isa<BranchInst>(BBI) && cast<BranchInst>(BBI)->isUnconditional() &&
9296 BBI != Other->begin()) {
9297 --BBI;
9298 StoreInst *OtherStore = dyn_cast<StoreInst>(BBI);
9299
9300 // If this instruction is a store to the same location.
9301 if (OtherStore && OtherStore->getOperand(1) == SI.getOperand(1)) {
9302 // Okay, we know we can perform this transformation. Insert a PHI
9303 // node now if we need it.
9304 Value *MergedVal = OtherStore->getOperand(0);
9305 if (MergedVal != SI.getOperand(0)) {
9306 PHINode *PN = new PHINode(MergedVal->getType(), "storemerge");
9307 PN->reserveOperandSpace(2);
9308 PN->addIncoming(SI.getOperand(0), SI.getParent());
9309 PN->addIncoming(OtherStore->getOperand(0), Other);
9310 MergedVal = InsertNewInstBefore(PN, Dest->front());
9311 }
9312
9313 // Advance to a place where it is safe to insert the new store and
9314 // insert it.
9315 BBI = Dest->begin();
9316 while (isa<PHINode>(BBI)) ++BBI;
9317 InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
9318 OtherStore->isVolatile()), *BBI);
9319
9320 // Nuke the old stores.
Chris Lattner5997cf92006-02-08 03:25:32 +00009321 EraseInstFromFunction(SI);
9322 EraseInstFromFunction(*OtherStore);
Chris Lattner219175c2005-09-12 23:23:25 +00009323 ++NumCombined;
9324 return 0;
9325 }
9326 }
9327 }
9328 }
9329
Chris Lattner31f486c2005-01-31 05:36:43 +00009330 return 0;
9331}
9332
9333
Chris Lattner9eef8a72003-06-04 04:46:00 +00009334Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
9335 // Change br (not X), label True, label False to: br X, label False, True
Reid Spencer4fdd96c2005-06-18 17:37:34 +00009336 Value *X = 0;
Chris Lattnerd4252a72004-07-30 07:50:03 +00009337 BasicBlock *TrueDest;
9338 BasicBlock *FalseDest;
9339 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
9340 !isa<Constant>(X)) {
9341 // Swap Destinations and condition...
9342 BI.setCondition(X);
9343 BI.setSuccessor(0, FalseDest);
9344 BI.setSuccessor(1, TrueDest);
9345 return &BI;
9346 }
9347
Reid Spencer266e42b2006-12-23 06:05:41 +00009348 // Cannonicalize fcmp_one -> fcmp_oeq
9349 FCmpInst::Predicate FPred; Value *Y;
9350 if (match(&BI, m_Br(m_FCmp(FPred, m_Value(X), m_Value(Y)),
9351 TrueDest, FalseDest)))
9352 if ((FPred == FCmpInst::FCMP_ONE || FPred == FCmpInst::FCMP_OLE ||
9353 FPred == FCmpInst::FCMP_OGE) && BI.getCondition()->hasOneUse()) {
9354 FCmpInst *I = cast<FCmpInst>(BI.getCondition());
Reid Spencer266e42b2006-12-23 06:05:41 +00009355 FCmpInst::Predicate NewPred = FCmpInst::getInversePredicate(FPred);
Chris Lattner6e0123b2007-02-11 01:23:03 +00009356 Instruction *NewSCC = new FCmpInst(NewPred, X, Y, "", I);
9357 NewSCC->takeName(I);
Reid Spencer266e42b2006-12-23 06:05:41 +00009358 // Swap Destinations and condition...
9359 BI.setCondition(NewSCC);
9360 BI.setSuccessor(0, FalseDest);
9361 BI.setSuccessor(1, TrueDest);
Chris Lattnerb15e2b12007-03-02 21:28:56 +00009362 RemoveFromWorkList(I);
Chris Lattner6e0123b2007-02-11 01:23:03 +00009363 I->eraseFromParent();
Chris Lattnerb15e2b12007-03-02 21:28:56 +00009364 AddToWorkList(NewSCC);
Reid Spencer266e42b2006-12-23 06:05:41 +00009365 return &BI;
9366 }
9367
9368 // Cannonicalize icmp_ne -> icmp_eq
9369 ICmpInst::Predicate IPred;
9370 if (match(&BI, m_Br(m_ICmp(IPred, m_Value(X), m_Value(Y)),
9371 TrueDest, FalseDest)))
9372 if ((IPred == ICmpInst::ICMP_NE || IPred == ICmpInst::ICMP_ULE ||
9373 IPred == ICmpInst::ICMP_SLE || IPred == ICmpInst::ICMP_UGE ||
9374 IPred == ICmpInst::ICMP_SGE) && BI.getCondition()->hasOneUse()) {
9375 ICmpInst *I = cast<ICmpInst>(BI.getCondition());
Reid Spencer266e42b2006-12-23 06:05:41 +00009376 ICmpInst::Predicate NewPred = ICmpInst::getInversePredicate(IPred);
Chris Lattner6e0123b2007-02-11 01:23:03 +00009377 Instruction *NewSCC = new ICmpInst(NewPred, X, Y, "", I);
9378 NewSCC->takeName(I);
Chris Lattnere967b342003-06-04 05:10:11 +00009379 // Swap Destinations and condition...
Chris Lattnerd4252a72004-07-30 07:50:03 +00009380 BI.setCondition(NewSCC);
Chris Lattnere967b342003-06-04 05:10:11 +00009381 BI.setSuccessor(0, FalseDest);
9382 BI.setSuccessor(1, TrueDest);
Chris Lattnerb15e2b12007-03-02 21:28:56 +00009383 RemoveFromWorkList(I);
Chris Lattner6e0123b2007-02-11 01:23:03 +00009384 I->eraseFromParent();;
Chris Lattnerb15e2b12007-03-02 21:28:56 +00009385 AddToWorkList(NewSCC);
Chris Lattnere967b342003-06-04 05:10:11 +00009386 return &BI;
9387 }
Misha Brukmanb1c93172005-04-21 23:48:37 +00009388
Chris Lattner9eef8a72003-06-04 04:46:00 +00009389 return 0;
9390}
Chris Lattner1085bdf2002-11-04 16:18:53 +00009391
Chris Lattner4c9c20a2004-07-03 00:26:11 +00009392Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
9393 Value *Cond = SI.getCondition();
9394 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
9395 if (I->getOpcode() == Instruction::Add)
9396 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
9397 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
9398 for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
Chris Lattner81a7a232004-10-16 18:11:37 +00009399 SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
Chris Lattner4c9c20a2004-07-03 00:26:11 +00009400 AddRHS));
9401 SI.setOperand(0, I->getOperand(0));
Chris Lattnerb15e2b12007-03-02 21:28:56 +00009402 AddToWorkList(I);
Chris Lattner4c9c20a2004-07-03 00:26:11 +00009403 return &SI;
9404 }
9405 }
9406 return 0;
9407}
9408
Chris Lattner6bc98652006-03-05 00:22:33 +00009409/// CheapToScalarize - Return true if the value is cheaper to scalarize than it
9410/// is to leave as a vector operation.
9411static bool CheapToScalarize(Value *V, bool isConstant) {
9412 if (isa<ConstantAggregateZero>(V))
9413 return true;
Reid Spencerd84d35b2007-02-15 02:26:10 +00009414 if (ConstantVector *C = dyn_cast<ConstantVector>(V)) {
Chris Lattner6bc98652006-03-05 00:22:33 +00009415 if (isConstant) return true;
9416 // If all elts are the same, we can extract.
9417 Constant *Op0 = C->getOperand(0);
9418 for (unsigned i = 1; i < C->getNumOperands(); ++i)
9419 if (C->getOperand(i) != Op0)
9420 return false;
9421 return true;
9422 }
9423 Instruction *I = dyn_cast<Instruction>(V);
9424 if (!I) return false;
9425
9426 // Insert element gets simplified to the inserted element or is deleted if
9427 // this is constant idx extract element and its a constant idx insertelt.
9428 if (I->getOpcode() == Instruction::InsertElement && isConstant &&
9429 isa<ConstantInt>(I->getOperand(2)))
9430 return true;
9431 if (I->getOpcode() == Instruction::Load && I->hasOneUse())
9432 return true;
9433 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I))
9434 if (BO->hasOneUse() &&
9435 (CheapToScalarize(BO->getOperand(0), isConstant) ||
9436 CheapToScalarize(BO->getOperand(1), isConstant)))
9437 return true;
Reid Spencer266e42b2006-12-23 06:05:41 +00009438 if (CmpInst *CI = dyn_cast<CmpInst>(I))
9439 if (CI->hasOneUse() &&
9440 (CheapToScalarize(CI->getOperand(0), isConstant) ||
9441 CheapToScalarize(CI->getOperand(1), isConstant)))
9442 return true;
Chris Lattner6bc98652006-03-05 00:22:33 +00009443
9444 return false;
9445}
9446
Chris Lattner945e4372007-02-14 05:52:17 +00009447/// Read and decode a shufflevector mask.
9448///
9449/// It turns undef elements into values that are larger than the number of
9450/// elements in the input.
Chris Lattner12249be2006-05-25 23:48:38 +00009451static std::vector<unsigned> getShuffleMask(const ShuffleVectorInst *SVI) {
9452 unsigned NElts = SVI->getType()->getNumElements();
9453 if (isa<ConstantAggregateZero>(SVI->getOperand(2)))
9454 return std::vector<unsigned>(NElts, 0);
9455 if (isa<UndefValue>(SVI->getOperand(2)))
9456 return std::vector<unsigned>(NElts, 2*NElts);
9457
9458 std::vector<unsigned> Result;
Reid Spencerd84d35b2007-02-15 02:26:10 +00009459 const ConstantVector *CP = cast<ConstantVector>(SVI->getOperand(2));
Chris Lattner12249be2006-05-25 23:48:38 +00009460 for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i)
9461 if (isa<UndefValue>(CP->getOperand(i)))
9462 Result.push_back(NElts*2); // undef -> 8
9463 else
Reid Spencere0fc4df2006-10-20 07:07:24 +00009464 Result.push_back(cast<ConstantInt>(CP->getOperand(i))->getZExtValue());
Chris Lattner12249be2006-05-25 23:48:38 +00009465 return Result;
9466}
9467
Chris Lattner8d1d8d32006-03-31 23:01:56 +00009468/// FindScalarElement - Given a vector and an element number, see if the scalar
9469/// value is already around as a register, for example if it were inserted then
9470/// extracted from the vector.
9471static Value *FindScalarElement(Value *V, unsigned EltNo) {
Reid Spencerd84d35b2007-02-15 02:26:10 +00009472 assert(isa<VectorType>(V->getType()) && "Not looking at a vector?");
9473 const VectorType *PTy = cast<VectorType>(V->getType());
Chris Lattner2d37f922006-04-10 23:06:36 +00009474 unsigned Width = PTy->getNumElements();
9475 if (EltNo >= Width) // Out of range access.
Chris Lattner8d1d8d32006-03-31 23:01:56 +00009476 return UndefValue::get(PTy->getElementType());
9477
9478 if (isa<UndefValue>(V))
9479 return UndefValue::get(PTy->getElementType());
9480 else if (isa<ConstantAggregateZero>(V))
9481 return Constant::getNullValue(PTy->getElementType());
Reid Spencerd84d35b2007-02-15 02:26:10 +00009482 else if (ConstantVector *CP = dyn_cast<ConstantVector>(V))
Chris Lattner8d1d8d32006-03-31 23:01:56 +00009483 return CP->getOperand(EltNo);
9484 else if (InsertElementInst *III = dyn_cast<InsertElementInst>(V)) {
9485 // If this is an insert to a variable element, we don't know what it is.
Reid Spencere0fc4df2006-10-20 07:07:24 +00009486 if (!isa<ConstantInt>(III->getOperand(2)))
9487 return 0;
9488 unsigned IIElt = cast<ConstantInt>(III->getOperand(2))->getZExtValue();
Chris Lattner8d1d8d32006-03-31 23:01:56 +00009489
9490 // If this is an insert to the element we are looking for, return the
9491 // inserted value.
Reid Spencere0fc4df2006-10-20 07:07:24 +00009492 if (EltNo == IIElt)
9493 return III->getOperand(1);
Chris Lattner8d1d8d32006-03-31 23:01:56 +00009494
9495 // Otherwise, the insertelement doesn't modify the value, recurse on its
9496 // vector input.
9497 return FindScalarElement(III->getOperand(0), EltNo);
Chris Lattner2d37f922006-04-10 23:06:36 +00009498 } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(V)) {
Chris Lattner12249be2006-05-25 23:48:38 +00009499 unsigned InEl = getShuffleMask(SVI)[EltNo];
9500 if (InEl < Width)
9501 return FindScalarElement(SVI->getOperand(0), InEl);
9502 else if (InEl < Width*2)
9503 return FindScalarElement(SVI->getOperand(1), InEl - Width);
9504 else
9505 return UndefValue::get(PTy->getElementType());
Chris Lattner8d1d8d32006-03-31 23:01:56 +00009506 }
9507
9508 // Otherwise, we don't know.
9509 return 0;
9510}
9511
Robert Bocchinoa8352962006-01-13 22:48:06 +00009512Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
Chris Lattner8d1d8d32006-03-31 23:01:56 +00009513
Chris Lattner92346c32006-03-31 18:25:14 +00009514 // If packed val is undef, replace extract with scalar undef.
9515 if (isa<UndefValue>(EI.getOperand(0)))
9516 return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
9517
9518 // If packed val is constant 0, replace extract with scalar 0.
9519 if (isa<ConstantAggregateZero>(EI.getOperand(0)))
9520 return ReplaceInstUsesWith(EI, Constant::getNullValue(EI.getType()));
9521
Reid Spencerd84d35b2007-02-15 02:26:10 +00009522 if (ConstantVector *C = dyn_cast<ConstantVector>(EI.getOperand(0))) {
Robert Bocchinoa8352962006-01-13 22:48:06 +00009523 // If packed val is constant with uniform operands, replace EI
9524 // with that operand
Chris Lattner6bc98652006-03-05 00:22:33 +00009525 Constant *op0 = C->getOperand(0);
Robert Bocchinoa8352962006-01-13 22:48:06 +00009526 for (unsigned i = 1; i < C->getNumOperands(); ++i)
Chris Lattner6bc98652006-03-05 00:22:33 +00009527 if (C->getOperand(i) != op0) {
9528 op0 = 0;
9529 break;
9530 }
9531 if (op0)
9532 return ReplaceInstUsesWith(EI, op0);
Robert Bocchinoa8352962006-01-13 22:48:06 +00009533 }
Chris Lattner6bc98652006-03-05 00:22:33 +00009534
Chris Lattner8d1d8d32006-03-31 23:01:56 +00009535 // If extracting a specified index from the vector, see if we can recursively
9536 // find a previously computed scalar that was inserted into the vector.
Reid Spencere0fc4df2006-10-20 07:07:24 +00009537 if (ConstantInt *IdxC = dyn_cast<ConstantInt>(EI.getOperand(1))) {
Chris Lattner2deeaea2006-10-05 06:55:50 +00009538 // This instruction only demands the single element from the input vector.
9539 // If the input vector has a single use, simplify it based on this use
9540 // property.
Reid Spencere0fc4df2006-10-20 07:07:24 +00009541 uint64_t IndexVal = IdxC->getZExtValue();
Chris Lattner2deeaea2006-10-05 06:55:50 +00009542 if (EI.getOperand(0)->hasOneUse()) {
9543 uint64_t UndefElts;
9544 if (Value *V = SimplifyDemandedVectorElts(EI.getOperand(0),
Reid Spencere0fc4df2006-10-20 07:07:24 +00009545 1 << IndexVal,
Chris Lattner2deeaea2006-10-05 06:55:50 +00009546 UndefElts)) {
9547 EI.setOperand(0, V);
9548 return &EI;
9549 }
9550 }
9551
Reid Spencere0fc4df2006-10-20 07:07:24 +00009552 if (Value *Elt = FindScalarElement(EI.getOperand(0), IndexVal))
Chris Lattner8d1d8d32006-03-31 23:01:56 +00009553 return ReplaceInstUsesWith(EI, Elt);
Chris Lattner2d37f922006-04-10 23:06:36 +00009554 }
Chris Lattner8d1d8d32006-03-31 23:01:56 +00009555
Chris Lattner83f65782006-05-25 22:53:38 +00009556 if (Instruction *I = dyn_cast<Instruction>(EI.getOperand(0))) {
Robert Bocchinoa8352962006-01-13 22:48:06 +00009557 if (I->hasOneUse()) {
9558 // Push extractelement into predecessor operation if legal and
9559 // profitable to do so
9560 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
Chris Lattner6bc98652006-03-05 00:22:33 +00009561 bool isConstantElt = isa<ConstantInt>(EI.getOperand(1));
9562 if (CheapToScalarize(BO, isConstantElt)) {
9563 ExtractElementInst *newEI0 =
9564 new ExtractElementInst(BO->getOperand(0), EI.getOperand(1),
9565 EI.getName()+".lhs");
9566 ExtractElementInst *newEI1 =
9567 new ExtractElementInst(BO->getOperand(1), EI.getOperand(1),
9568 EI.getName()+".rhs");
9569 InsertNewInstBefore(newEI0, EI);
9570 InsertNewInstBefore(newEI1, EI);
9571 return BinaryOperator::create(BO->getOpcode(), newEI0, newEI1);
9572 }
Reid Spencerde46e482006-11-02 20:25:50 +00009573 } else if (isa<LoadInst>(I)) {
Reid Spencer13bc5d72006-12-12 09:18:51 +00009574 Value *Ptr = InsertCastBefore(Instruction::BitCast, I->getOperand(0),
Robert Bocchinoa8352962006-01-13 22:48:06 +00009575 PointerType::get(EI.getType()), EI);
9576 GetElementPtrInst *GEP =
Reid Spencera736fdf2006-11-29 01:11:01 +00009577 new GetElementPtrInst(Ptr, EI.getOperand(1), I->getName() + ".gep");
Robert Bocchinoa8352962006-01-13 22:48:06 +00009578 InsertNewInstBefore(GEP, EI);
9579 return new LoadInst(GEP);
Chris Lattner83f65782006-05-25 22:53:38 +00009580 }
9581 }
9582 if (InsertElementInst *IE = dyn_cast<InsertElementInst>(I)) {
9583 // Extracting the inserted element?
9584 if (IE->getOperand(2) == EI.getOperand(1))
9585 return ReplaceInstUsesWith(EI, IE->getOperand(1));
9586 // If the inserted and extracted elements are constants, they must not
9587 // be the same value, extract from the pre-inserted value instead.
9588 if (isa<Constant>(IE->getOperand(2)) &&
9589 isa<Constant>(EI.getOperand(1))) {
9590 AddUsesToWorkList(EI);
9591 EI.setOperand(0, IE->getOperand(0));
9592 return &EI;
9593 }
9594 } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I)) {
9595 // If this is extracting an element from a shufflevector, figure out where
9596 // it came from and extract from the appropriate input element instead.
Reid Spencere0fc4df2006-10-20 07:07:24 +00009597 if (ConstantInt *Elt = dyn_cast<ConstantInt>(EI.getOperand(1))) {
9598 unsigned SrcIdx = getShuffleMask(SVI)[Elt->getZExtValue()];
Chris Lattner12249be2006-05-25 23:48:38 +00009599 Value *Src;
9600 if (SrcIdx < SVI->getType()->getNumElements())
9601 Src = SVI->getOperand(0);
9602 else if (SrcIdx < SVI->getType()->getNumElements()*2) {
9603 SrcIdx -= SVI->getType()->getNumElements();
9604 Src = SVI->getOperand(1);
9605 } else {
9606 return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
Chris Lattner612fa8e2006-03-30 22:02:40 +00009607 }
Chris Lattner2deeaea2006-10-05 06:55:50 +00009608 return new ExtractElementInst(Src, SrcIdx);
Robert Bocchinoa8352962006-01-13 22:48:06 +00009609 }
9610 }
Chris Lattner83f65782006-05-25 22:53:38 +00009611 }
Robert Bocchinoa8352962006-01-13 22:48:06 +00009612 return 0;
9613}
9614
Chris Lattner90951862006-04-16 00:51:47 +00009615/// CollectSingleShuffleElements - If V is a shuffle of values that ONLY returns
9616/// elements from either LHS or RHS, return the shuffle mask and true.
9617/// Otherwise, return false.
9618static bool CollectSingleShuffleElements(Value *V, Value *LHS, Value *RHS,
9619 std::vector<Constant*> &Mask) {
9620 assert(V->getType() == LHS->getType() && V->getType() == RHS->getType() &&
9621 "Invalid CollectSingleShuffleElements");
Reid Spencerd84d35b2007-02-15 02:26:10 +00009622 unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
Chris Lattner90951862006-04-16 00:51:47 +00009623
9624 if (isa<UndefValue>(V)) {
Reid Spencerc635f472006-12-31 05:48:39 +00009625 Mask.assign(NumElts, UndefValue::get(Type::Int32Ty));
Chris Lattner90951862006-04-16 00:51:47 +00009626 return true;
9627 } else if (V == LHS) {
9628 for (unsigned i = 0; i != NumElts; ++i)
Reid Spencerc635f472006-12-31 05:48:39 +00009629 Mask.push_back(ConstantInt::get(Type::Int32Ty, i));
Chris Lattner90951862006-04-16 00:51:47 +00009630 return true;
9631 } else if (V == RHS) {
9632 for (unsigned i = 0; i != NumElts; ++i)
Reid Spencerc635f472006-12-31 05:48:39 +00009633 Mask.push_back(ConstantInt::get(Type::Int32Ty, i+NumElts));
Chris Lattner90951862006-04-16 00:51:47 +00009634 return true;
9635 } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
9636 // If this is an insert of an extract from some other vector, include it.
9637 Value *VecOp = IEI->getOperand(0);
9638 Value *ScalarOp = IEI->getOperand(1);
9639 Value *IdxOp = IEI->getOperand(2);
9640
Chris Lattnerb6cb64b2006-04-27 21:14:21 +00009641 if (!isa<ConstantInt>(IdxOp))
9642 return false;
Reid Spencere0fc4df2006-10-20 07:07:24 +00009643 unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
Chris Lattnerb6cb64b2006-04-27 21:14:21 +00009644
9645 if (isa<UndefValue>(ScalarOp)) { // inserting undef into vector.
9646 // Okay, we can handle this if the vector we are insertinting into is
9647 // transitively ok.
9648 if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
9649 // If so, update the mask to reflect the inserted undef.
Reid Spencerc635f472006-12-31 05:48:39 +00009650 Mask[InsertedIdx] = UndefValue::get(Type::Int32Ty);
Chris Lattnerb6cb64b2006-04-27 21:14:21 +00009651 return true;
9652 }
9653 } else if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)){
9654 if (isa<ConstantInt>(EI->getOperand(1)) &&
Chris Lattner90951862006-04-16 00:51:47 +00009655 EI->getOperand(0)->getType() == V->getType()) {
9656 unsigned ExtractedIdx =
Reid Spencere0fc4df2006-10-20 07:07:24 +00009657 cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
Chris Lattner90951862006-04-16 00:51:47 +00009658
9659 // This must be extracting from either LHS or RHS.
9660 if (EI->getOperand(0) == LHS || EI->getOperand(0) == RHS) {
9661 // Okay, we can handle this if the vector we are insertinting into is
9662 // transitively ok.
9663 if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
9664 // If so, update the mask to reflect the inserted value.
9665 if (EI->getOperand(0) == LHS) {
9666 Mask[InsertedIdx & (NumElts-1)] =
Reid Spencerc635f472006-12-31 05:48:39 +00009667 ConstantInt::get(Type::Int32Ty, ExtractedIdx);
Chris Lattner90951862006-04-16 00:51:47 +00009668 } else {
9669 assert(EI->getOperand(0) == RHS);
9670 Mask[InsertedIdx & (NumElts-1)] =
Reid Spencerc635f472006-12-31 05:48:39 +00009671 ConstantInt::get(Type::Int32Ty, ExtractedIdx+NumElts);
Chris Lattner90951862006-04-16 00:51:47 +00009672
9673 }
9674 return true;
9675 }
9676 }
9677 }
9678 }
9679 }
9680 // TODO: Handle shufflevector here!
9681
9682 return false;
9683}
9684
9685/// CollectShuffleElements - We are building a shuffle of V, using RHS as the
9686/// RHS of the shuffle instruction, if it is not null. Return a shuffle mask
9687/// that computes V and the LHS value of the shuffle.
Chris Lattner39fac442006-04-15 01:39:45 +00009688static Value *CollectShuffleElements(Value *V, std::vector<Constant*> &Mask,
Chris Lattner90951862006-04-16 00:51:47 +00009689 Value *&RHS) {
Reid Spencerd84d35b2007-02-15 02:26:10 +00009690 assert(isa<VectorType>(V->getType()) &&
Chris Lattner90951862006-04-16 00:51:47 +00009691 (RHS == 0 || V->getType() == RHS->getType()) &&
Chris Lattner39fac442006-04-15 01:39:45 +00009692 "Invalid shuffle!");
Reid Spencerd84d35b2007-02-15 02:26:10 +00009693 unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
Chris Lattner39fac442006-04-15 01:39:45 +00009694
9695 if (isa<UndefValue>(V)) {
Reid Spencerc635f472006-12-31 05:48:39 +00009696 Mask.assign(NumElts, UndefValue::get(Type::Int32Ty));
Chris Lattner39fac442006-04-15 01:39:45 +00009697 return V;
9698 } else if (isa<ConstantAggregateZero>(V)) {
Reid Spencerc635f472006-12-31 05:48:39 +00009699 Mask.assign(NumElts, ConstantInt::get(Type::Int32Ty, 0));
Chris Lattner39fac442006-04-15 01:39:45 +00009700 return V;
9701 } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
9702 // If this is an insert of an extract from some other vector, include it.
9703 Value *VecOp = IEI->getOperand(0);
9704 Value *ScalarOp = IEI->getOperand(1);
9705 Value *IdxOp = IEI->getOperand(2);
9706
9707 if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
9708 if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
9709 EI->getOperand(0)->getType() == V->getType()) {
9710 unsigned ExtractedIdx =
Reid Spencere0fc4df2006-10-20 07:07:24 +00009711 cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
9712 unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
Chris Lattner39fac442006-04-15 01:39:45 +00009713
9714 // Either the extracted from or inserted into vector must be RHSVec,
9715 // otherwise we'd end up with a shuffle of three inputs.
Chris Lattner90951862006-04-16 00:51:47 +00009716 if (EI->getOperand(0) == RHS || RHS == 0) {
9717 RHS = EI->getOperand(0);
9718 Value *V = CollectShuffleElements(VecOp, Mask, RHS);
Chris Lattner39fac442006-04-15 01:39:45 +00009719 Mask[InsertedIdx & (NumElts-1)] =
Reid Spencerc635f472006-12-31 05:48:39 +00009720 ConstantInt::get(Type::Int32Ty, NumElts+ExtractedIdx);
Chris Lattner39fac442006-04-15 01:39:45 +00009721 return V;
9722 }
9723
Chris Lattner90951862006-04-16 00:51:47 +00009724 if (VecOp == RHS) {
9725 Value *V = CollectShuffleElements(EI->getOperand(0), Mask, RHS);
Chris Lattner39fac442006-04-15 01:39:45 +00009726 // Everything but the extracted element is replaced with the RHS.
9727 for (unsigned i = 0; i != NumElts; ++i) {
9728 if (i != InsertedIdx)
Reid Spencerc635f472006-12-31 05:48:39 +00009729 Mask[i] = ConstantInt::get(Type::Int32Ty, NumElts+i);
Chris Lattner39fac442006-04-15 01:39:45 +00009730 }
9731 return V;
9732 }
Chris Lattner90951862006-04-16 00:51:47 +00009733
9734 // If this insertelement is a chain that comes from exactly these two
9735 // vectors, return the vector and the effective shuffle.
9736 if (CollectSingleShuffleElements(IEI, EI->getOperand(0), RHS, Mask))
9737 return EI->getOperand(0);
9738
Chris Lattner39fac442006-04-15 01:39:45 +00009739 }
9740 }
9741 }
Chris Lattner90951862006-04-16 00:51:47 +00009742 // TODO: Handle shufflevector here!
Chris Lattner39fac442006-04-15 01:39:45 +00009743
9744 // Otherwise, can't do anything fancy. Return an identity vector.
9745 for (unsigned i = 0; i != NumElts; ++i)
Reid Spencerc635f472006-12-31 05:48:39 +00009746 Mask.push_back(ConstantInt::get(Type::Int32Ty, i));
Chris Lattner39fac442006-04-15 01:39:45 +00009747 return V;
9748}
9749
9750Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
9751 Value *VecOp = IE.getOperand(0);
9752 Value *ScalarOp = IE.getOperand(1);
9753 Value *IdxOp = IE.getOperand(2);
9754
9755 // If the inserted element was extracted from some other vector, and if the
9756 // indexes are constant, try to turn this into a shufflevector operation.
9757 if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
9758 if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
9759 EI->getOperand(0)->getType() == IE.getType()) {
9760 unsigned NumVectorElts = IE.getType()->getNumElements();
Reid Spencere0fc4df2006-10-20 07:07:24 +00009761 unsigned ExtractedIdx=cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
9762 unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
Chris Lattner39fac442006-04-15 01:39:45 +00009763
9764 if (ExtractedIdx >= NumVectorElts) // Out of range extract.
9765 return ReplaceInstUsesWith(IE, VecOp);
9766
9767 if (InsertedIdx >= NumVectorElts) // Out of range insert.
9768 return ReplaceInstUsesWith(IE, UndefValue::get(IE.getType()));
9769
9770 // If we are extracting a value from a vector, then inserting it right
9771 // back into the same place, just use the input vector.
9772 if (EI->getOperand(0) == VecOp && ExtractedIdx == InsertedIdx)
9773 return ReplaceInstUsesWith(IE, VecOp);
9774
9775 // We could theoretically do this for ANY input. However, doing so could
9776 // turn chains of insertelement instructions into a chain of shufflevector
9777 // instructions, and right now we do not merge shufflevectors. As such,
9778 // only do this in a situation where it is clear that there is benefit.
9779 if (isa<UndefValue>(VecOp) || isa<ConstantAggregateZero>(VecOp)) {
9780 // Turn this into shuffle(EIOp0, VecOp, Mask). The result has all of
9781 // the values of VecOp, except then one read from EIOp0.
9782 // Build a new shuffle mask.
9783 std::vector<Constant*> Mask;
9784 if (isa<UndefValue>(VecOp))
Reid Spencerc635f472006-12-31 05:48:39 +00009785 Mask.assign(NumVectorElts, UndefValue::get(Type::Int32Ty));
Chris Lattner39fac442006-04-15 01:39:45 +00009786 else {
9787 assert(isa<ConstantAggregateZero>(VecOp) && "Unknown thing");
Reid Spencerc635f472006-12-31 05:48:39 +00009788 Mask.assign(NumVectorElts, ConstantInt::get(Type::Int32Ty,
Chris Lattner39fac442006-04-15 01:39:45 +00009789 NumVectorElts));
9790 }
Reid Spencerc635f472006-12-31 05:48:39 +00009791 Mask[InsertedIdx] = ConstantInt::get(Type::Int32Ty, ExtractedIdx);
Chris Lattner39fac442006-04-15 01:39:45 +00009792 return new ShuffleVectorInst(EI->getOperand(0), VecOp,
Reid Spencerd84d35b2007-02-15 02:26:10 +00009793 ConstantVector::get(Mask));
Chris Lattner39fac442006-04-15 01:39:45 +00009794 }
9795
9796 // If this insertelement isn't used by some other insertelement, turn it
9797 // (and any insertelements it points to), into one big shuffle.
9798 if (!IE.hasOneUse() || !isa<InsertElementInst>(IE.use_back())) {
9799 std::vector<Constant*> Mask;
Chris Lattner90951862006-04-16 00:51:47 +00009800 Value *RHS = 0;
9801 Value *LHS = CollectShuffleElements(&IE, Mask, RHS);
9802 if (RHS == 0) RHS = UndefValue::get(LHS->getType());
9803 // We now have a shuffle of LHS, RHS, Mask.
Reid Spencerd84d35b2007-02-15 02:26:10 +00009804 return new ShuffleVectorInst(LHS, RHS, ConstantVector::get(Mask));
Chris Lattner39fac442006-04-15 01:39:45 +00009805 }
9806 }
9807 }
9808
9809 return 0;
9810}
9811
9812
Chris Lattnerfbb77a42006-04-10 22:45:52 +00009813Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
9814 Value *LHS = SVI.getOperand(0);
9815 Value *RHS = SVI.getOperand(1);
Chris Lattner12249be2006-05-25 23:48:38 +00009816 std::vector<unsigned> Mask = getShuffleMask(&SVI);
Chris Lattnerfbb77a42006-04-10 22:45:52 +00009817
9818 bool MadeChange = false;
9819
Chris Lattner2deeaea2006-10-05 06:55:50 +00009820 // Undefined shuffle mask -> undefined value.
Chris Lattner12249be2006-05-25 23:48:38 +00009821 if (isa<UndefValue>(SVI.getOperand(2)))
Chris Lattnerfbb77a42006-04-10 22:45:52 +00009822 return ReplaceInstUsesWith(SVI, UndefValue::get(SVI.getType()));
9823
Chris Lattnerd7b6ea12007-01-05 07:36:08 +00009824 // If we have shuffle(x, undef, mask) and any elements of mask refer to
Chris Lattner39fac442006-04-15 01:39:45 +00009825 // the undef, change them to undefs.
Chris Lattnerd7b6ea12007-01-05 07:36:08 +00009826 if (isa<UndefValue>(SVI.getOperand(1))) {
9827 // Scan to see if there are any references to the RHS. If so, replace them
9828 // with undef element refs and set MadeChange to true.
9829 for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
9830 if (Mask[i] >= e && Mask[i] != 2*e) {
9831 Mask[i] = 2*e;
9832 MadeChange = true;
9833 }
9834 }
9835
9836 if (MadeChange) {
9837 // Remap any references to RHS to use LHS.
9838 std::vector<Constant*> Elts;
9839 for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
9840 if (Mask[i] == 2*e)
9841 Elts.push_back(UndefValue::get(Type::Int32Ty));
9842 else
9843 Elts.push_back(ConstantInt::get(Type::Int32Ty, Mask[i]));
9844 }
Reid Spencerd84d35b2007-02-15 02:26:10 +00009845 SVI.setOperand(2, ConstantVector::get(Elts));
Chris Lattnerd7b6ea12007-01-05 07:36:08 +00009846 }
9847 }
Chris Lattner39fac442006-04-15 01:39:45 +00009848
Chris Lattner12249be2006-05-25 23:48:38 +00009849 // Canonicalize shuffle(x ,x,mask) -> shuffle(x, undef,mask')
9850 // Canonicalize shuffle(undef,x,mask) -> shuffle(x, undef,mask').
9851 if (LHS == RHS || isa<UndefValue>(LHS)) {
9852 if (isa<UndefValue>(LHS) && LHS == RHS) {
Chris Lattnerfbb77a42006-04-10 22:45:52 +00009853 // shuffle(undef,undef,mask) -> undef.
9854 return ReplaceInstUsesWith(SVI, LHS);
9855 }
9856
Chris Lattner12249be2006-05-25 23:48:38 +00009857 // Remap any references to RHS to use LHS.
9858 std::vector<Constant*> Elts;
9859 for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
Chris Lattner0e477162006-05-26 00:29:06 +00009860 if (Mask[i] >= 2*e)
Reid Spencerc635f472006-12-31 05:48:39 +00009861 Elts.push_back(UndefValue::get(Type::Int32Ty));
Chris Lattner0e477162006-05-26 00:29:06 +00009862 else {
9863 if ((Mask[i] >= e && isa<UndefValue>(RHS)) ||
9864 (Mask[i] < e && isa<UndefValue>(LHS)))
9865 Mask[i] = 2*e; // Turn into undef.
9866 else
9867 Mask[i] &= (e-1); // Force to LHS.
Reid Spencerc635f472006-12-31 05:48:39 +00009868 Elts.push_back(ConstantInt::get(Type::Int32Ty, Mask[i]));
Chris Lattner0e477162006-05-26 00:29:06 +00009869 }
Chris Lattnerfbb77a42006-04-10 22:45:52 +00009870 }
Chris Lattner12249be2006-05-25 23:48:38 +00009871 SVI.setOperand(0, SVI.getOperand(1));
Chris Lattnerfbb77a42006-04-10 22:45:52 +00009872 SVI.setOperand(1, UndefValue::get(RHS->getType()));
Reid Spencerd84d35b2007-02-15 02:26:10 +00009873 SVI.setOperand(2, ConstantVector::get(Elts));
Chris Lattner0e477162006-05-26 00:29:06 +00009874 LHS = SVI.getOperand(0);
9875 RHS = SVI.getOperand(1);
Chris Lattnerfbb77a42006-04-10 22:45:52 +00009876 MadeChange = true;
9877 }
9878
Chris Lattner0e477162006-05-26 00:29:06 +00009879 // Analyze the shuffle, are the LHS or RHS and identity shuffles?
Chris Lattner12249be2006-05-25 23:48:38 +00009880 bool isLHSID = true, isRHSID = true;
Chris Lattner34cebe72006-04-16 00:03:56 +00009881
Chris Lattner12249be2006-05-25 23:48:38 +00009882 for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
9883 if (Mask[i] >= e*2) continue; // Ignore undef values.
9884 // Is this an identity shuffle of the LHS value?
9885 isLHSID &= (Mask[i] == i);
9886
9887 // Is this an identity shuffle of the RHS value?
9888 isRHSID &= (Mask[i]-e == i);
Chris Lattner34cebe72006-04-16 00:03:56 +00009889 }
Chris Lattnerfbb77a42006-04-10 22:45:52 +00009890
Chris Lattner12249be2006-05-25 23:48:38 +00009891 // Eliminate identity shuffles.
9892 if (isLHSID) return ReplaceInstUsesWith(SVI, LHS);
9893 if (isRHSID) return ReplaceInstUsesWith(SVI, RHS);
Chris Lattnerfbb77a42006-04-10 22:45:52 +00009894
Chris Lattner0e477162006-05-26 00:29:06 +00009895 // If the LHS is a shufflevector itself, see if we can combine it with this
9896 // one without producing an unusual shuffle. Here we are really conservative:
9897 // we are absolutely afraid of producing a shuffle mask not in the input
9898 // program, because the code gen may not be smart enough to turn a merged
9899 // shuffle into two specific shuffles: it may produce worse code. As such,
9900 // we only merge two shuffles if the result is one of the two input shuffle
9901 // masks. In this case, merging the shuffles just removes one instruction,
9902 // which we know is safe. This is good for things like turning:
9903 // (splat(splat)) -> splat.
9904 if (ShuffleVectorInst *LHSSVI = dyn_cast<ShuffleVectorInst>(LHS)) {
9905 if (isa<UndefValue>(RHS)) {
9906 std::vector<unsigned> LHSMask = getShuffleMask(LHSSVI);
9907
9908 std::vector<unsigned> NewMask;
9909 for (unsigned i = 0, e = Mask.size(); i != e; ++i)
9910 if (Mask[i] >= 2*e)
9911 NewMask.push_back(2*e);
9912 else
9913 NewMask.push_back(LHSMask[Mask[i]]);
9914
9915 // If the result mask is equal to the src shuffle or this shuffle mask, do
9916 // the replacement.
9917 if (NewMask == LHSMask || NewMask == Mask) {
9918 std::vector<Constant*> Elts;
9919 for (unsigned i = 0, e = NewMask.size(); i != e; ++i) {
9920 if (NewMask[i] >= e*2) {
Reid Spencerc635f472006-12-31 05:48:39 +00009921 Elts.push_back(UndefValue::get(Type::Int32Ty));
Chris Lattner0e477162006-05-26 00:29:06 +00009922 } else {
Reid Spencerc635f472006-12-31 05:48:39 +00009923 Elts.push_back(ConstantInt::get(Type::Int32Ty, NewMask[i]));
Chris Lattner0e477162006-05-26 00:29:06 +00009924 }
9925 }
9926 return new ShuffleVectorInst(LHSSVI->getOperand(0),
9927 LHSSVI->getOperand(1),
Reid Spencerd84d35b2007-02-15 02:26:10 +00009928 ConstantVector::get(Elts));
Chris Lattner0e477162006-05-26 00:29:06 +00009929 }
9930 }
9931 }
Chris Lattner4284f642007-01-30 22:32:46 +00009932
Chris Lattnerfbb77a42006-04-10 22:45:52 +00009933 return MadeChange ? &SVI : 0;
9934}
9935
9936
Robert Bocchinoa8352962006-01-13 22:48:06 +00009937
Chris Lattner39c98bb2004-12-08 23:43:58 +00009938
9939/// TryToSinkInstruction - Try to move the specified instruction from its
9940/// current block into the beginning of DestBlock, which can only happen if it's
9941/// safe to move the instruction past all of the instructions between it and the
9942/// end of its block.
9943static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
9944 assert(I->hasOneUse() && "Invariants didn't hold!");
9945
Chris Lattnerc4f67e62005-10-27 17:13:11 +00009946 // Cannot move control-flow-involving, volatile loads, vaarg, etc.
9947 if (isa<PHINode>(I) || I->mayWriteToMemory()) return false;
Misha Brukmanb1c93172005-04-21 23:48:37 +00009948
Chris Lattner39c98bb2004-12-08 23:43:58 +00009949 // Do not sink alloca instructions out of the entry block.
9950 if (isa<AllocaInst>(I) && I->getParent() == &DestBlock->getParent()->front())
9951 return false;
9952
Chris Lattnerf17a2fb2004-12-09 07:14:34 +00009953 // We can only sink load instructions if there is nothing between the load and
9954 // the end of block that could change the value.
9955 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
Chris Lattnerf17a2fb2004-12-09 07:14:34 +00009956 for (BasicBlock::iterator Scan = LI, E = LI->getParent()->end();
9957 Scan != E; ++Scan)
9958 if (Scan->mayWriteToMemory())
9959 return false;
Chris Lattnerf17a2fb2004-12-09 07:14:34 +00009960 }
Chris Lattner39c98bb2004-12-08 23:43:58 +00009961
9962 BasicBlock::iterator InsertPos = DestBlock->begin();
9963 while (isa<PHINode>(InsertPos)) ++InsertPos;
9964
Chris Lattner9f269e42005-08-08 19:11:57 +00009965 I->moveBefore(InsertPos);
Chris Lattner39c98bb2004-12-08 23:43:58 +00009966 ++NumSunkInst;
9967 return true;
9968}
9969
Chris Lattnera36ee4e2006-05-10 19:00:36 +00009970
9971/// AddReachableCodeToWorklist - Walk the function in depth-first order, adding
9972/// all reachable code to the worklist.
9973///
9974/// This has a couple of tricks to make the code faster and more powerful. In
9975/// particular, we constant fold and DCE instructions as we go, to avoid adding
9976/// them to the worklist (this significantly speeds up instcombine on code where
9977/// many instructions are dead or constant). Additionally, if we find a branch
9978/// whose condition is a known constant, we only visit the reachable successors.
9979///
9980static void AddReachableCodeToWorklist(BasicBlock *BB,
Chris Lattner7907e5f2007-02-15 19:41:52 +00009981 SmallPtrSet<BasicBlock*, 64> &Visited,
Chris Lattnerb15e2b12007-03-02 21:28:56 +00009982 InstCombiner &IC,
Chris Lattner1443bc52006-05-11 17:11:52 +00009983 const TargetData *TD) {
Chris Lattnera36ee4e2006-05-10 19:00:36 +00009984 // We have now visited this block! If we've already been here, bail out.
Chris Lattner7907e5f2007-02-15 19:41:52 +00009985 if (!Visited.insert(BB)) return;
Chris Lattnera36ee4e2006-05-10 19:00:36 +00009986
9987 for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
9988 Instruction *Inst = BBI++;
9989
9990 // DCE instruction if trivially dead.
9991 if (isInstructionTriviallyDead(Inst)) {
9992 ++NumDeadInst;
Bill Wendling5dbf43c2006-11-26 09:46:52 +00009993 DOUT << "IC: DCE: " << *Inst;
Chris Lattnera36ee4e2006-05-10 19:00:36 +00009994 Inst->eraseFromParent();
9995 continue;
9996 }
9997
9998 // ConstantProp instruction if trivially constant.
Chris Lattnere3eda252007-01-30 23:16:15 +00009999 if (Constant *C = ConstantFoldInstruction(Inst, TD)) {
Bill Wendling5dbf43c2006-11-26 09:46:52 +000010000 DOUT << "IC: ConstFold to: " << *C << " from: " << *Inst;
Chris Lattnera36ee4e2006-05-10 19:00:36 +000010001 Inst->replaceAllUsesWith(C);
10002 ++NumConstProp;
10003 Inst->eraseFromParent();
10004 continue;
10005 }
10006
Chris Lattnerb15e2b12007-03-02 21:28:56 +000010007 IC.AddToWorkList(Inst);
Chris Lattnera36ee4e2006-05-10 19:00:36 +000010008 }
10009
10010 // Recursively visit successors. If this is a branch or switch on a constant,
10011 // only visit the reachable successor.
10012 TerminatorInst *TI = BB->getTerminator();
10013 if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
Reid Spencer7a9c62b2007-01-12 07:05:14 +000010014 if (BI->isConditional() && isa<ConstantInt>(BI->getCondition())) {
Reid Spencercddc9df2007-01-12 04:24:46 +000010015 bool CondVal = cast<ConstantInt>(BI->getCondition())->getZExtValue();
Chris Lattnerb15e2b12007-03-02 21:28:56 +000010016 AddReachableCodeToWorklist(BI->getSuccessor(!CondVal), Visited, IC, TD);
Chris Lattnera36ee4e2006-05-10 19:00:36 +000010017 return;
10018 }
10019 } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
10020 if (ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition())) {
10021 // See if this is an explicit destination.
10022 for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i)
10023 if (SI->getCaseValue(i) == Cond) {
Chris Lattnerb15e2b12007-03-02 21:28:56 +000010024 AddReachableCodeToWorklist(SI->getSuccessor(i), Visited, IC, TD);
Chris Lattnera36ee4e2006-05-10 19:00:36 +000010025 return;
10026 }
10027
10028 // Otherwise it is the default destination.
Chris Lattnerb15e2b12007-03-02 21:28:56 +000010029 AddReachableCodeToWorklist(SI->getSuccessor(0), Visited, IC, TD);
Chris Lattnera36ee4e2006-05-10 19:00:36 +000010030 return;
10031 }
10032 }
10033
10034 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
Chris Lattnerb15e2b12007-03-02 21:28:56 +000010035 AddReachableCodeToWorklist(TI->getSuccessor(i), Visited, IC, TD);
Chris Lattnera36ee4e2006-05-10 19:00:36 +000010036}
10037
Chris Lattner960a5432007-03-03 02:04:50 +000010038bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
Chris Lattner260ab202002-04-18 17:39:14 +000010039 bool Changed = false;
Chris Lattnerf4ad1652003-11-02 05:57:39 +000010040 TD = &getAnalysis<TargetData>();
Chris Lattner960a5432007-03-03 02:04:50 +000010041
10042 DEBUG(DOUT << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
10043 << F.getNameStr() << "\n");
Chris Lattnerca081252001-12-14 16:52:21 +000010044
Chris Lattner4ed40f72005-07-07 20:40:38 +000010045 {
Chris Lattnera36ee4e2006-05-10 19:00:36 +000010046 // Do a depth-first traversal of the function, populate the worklist with
10047 // the reachable instructions. Ignore blocks that are not reachable. Keep
10048 // track of which blocks we visit.
Chris Lattner7907e5f2007-02-15 19:41:52 +000010049 SmallPtrSet<BasicBlock*, 64> Visited;
Chris Lattnerb15e2b12007-03-02 21:28:56 +000010050 AddReachableCodeToWorklist(F.begin(), Visited, *this, TD);
Jeff Cohen5f4ef3c2005-07-27 06:12:32 +000010051
Chris Lattner4ed40f72005-07-07 20:40:38 +000010052 // Do a quick scan over the function. If we find any blocks that are
10053 // unreachable, remove any instructions inside of them. This prevents
10054 // the instcombine code from having to deal with some bad special cases.
10055 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
10056 if (!Visited.count(BB)) {
10057 Instruction *Term = BB->getTerminator();
10058 while (Term != BB->begin()) { // Remove instrs bottom-up
10059 BasicBlock::iterator I = Term; --I;
Chris Lattner2d3a7a62004-04-27 15:13:33 +000010060
Bill Wendling5dbf43c2006-11-26 09:46:52 +000010061 DOUT << "IC: DCE: " << *I;
Chris Lattner4ed40f72005-07-07 20:40:38 +000010062 ++NumDeadInst;
10063
10064 if (!I->use_empty())
10065 I->replaceAllUsesWith(UndefValue::get(I->getType()));
10066 I->eraseFromParent();
10067 }
10068 }
10069 }
Chris Lattnerca081252001-12-14 16:52:21 +000010070
Chris Lattnerb15e2b12007-03-02 21:28:56 +000010071 while (!Worklist.empty()) {
10072 Instruction *I = RemoveOneFromWorkList();
10073 if (I == 0) continue; // skip null values.
Chris Lattnerca081252001-12-14 16:52:21 +000010074
Chris Lattner1443bc52006-05-11 17:11:52 +000010075 // Check to see if we can DCE the instruction.
Chris Lattner99f48c62002-09-02 04:59:56 +000010076 if (isInstructionTriviallyDead(I)) {
Chris Lattner1443bc52006-05-11 17:11:52 +000010077 // Add operands to the worklist.
Chris Lattnere8ed4ef2003-10-06 17:11:01 +000010078 if (I->getNumOperands() < 4)
Chris Lattner51ea1272004-02-28 05:22:00 +000010079 AddUsesToWorkList(*I);
Chris Lattner99f48c62002-09-02 04:59:56 +000010080 ++NumDeadInst;
Chris Lattnere8ed4ef2003-10-06 17:11:01 +000010081
Bill Wendling5dbf43c2006-11-26 09:46:52 +000010082 DOUT << "IC: DCE: " << *I;
Chris Lattnercd517ff2005-01-28 19:32:01 +000010083
10084 I->eraseFromParent();
Chris Lattnerb15e2b12007-03-02 21:28:56 +000010085 RemoveFromWorkList(I);
Chris Lattnere8ed4ef2003-10-06 17:11:01 +000010086 continue;
10087 }
Chris Lattner99f48c62002-09-02 04:59:56 +000010088
Chris Lattner1443bc52006-05-11 17:11:52 +000010089 // Instruction isn't dead, see if we can constant propagate it.
Chris Lattnere3eda252007-01-30 23:16:15 +000010090 if (Constant *C = ConstantFoldInstruction(I, TD)) {
Bill Wendling5dbf43c2006-11-26 09:46:52 +000010091 DOUT << "IC: ConstFold to: " << *C << " from: " << *I;
Chris Lattnercd517ff2005-01-28 19:32:01 +000010092
Chris Lattner1443bc52006-05-11 17:11:52 +000010093 // Add operands to the worklist.
Chris Lattner51ea1272004-02-28 05:22:00 +000010094 AddUsesToWorkList(*I);
Chris Lattnerc6509f42002-12-05 22:41:53 +000010095 ReplaceInstUsesWith(*I, C);
10096
Chris Lattner99f48c62002-09-02 04:59:56 +000010097 ++NumConstProp;
Chris Lattnera36ee4e2006-05-10 19:00:36 +000010098 I->eraseFromParent();
Chris Lattnerb15e2b12007-03-02 21:28:56 +000010099 RemoveFromWorkList(I);
Chris Lattnere8ed4ef2003-10-06 17:11:01 +000010100 continue;
Chris Lattner99f48c62002-09-02 04:59:56 +000010101 }
Chris Lattnere8ed4ef2003-10-06 17:11:01 +000010102
Chris Lattner39c98bb2004-12-08 23:43:58 +000010103 // See if we can trivially sink this instruction to a successor basic block.
10104 if (I->hasOneUse()) {
10105 BasicBlock *BB = I->getParent();
10106 BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent();
10107 if (UserParent != BB) {
10108 bool UserIsSuccessor = false;
10109 // See if the user is one of our successors.
10110 for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
10111 if (*SI == UserParent) {
10112 UserIsSuccessor = true;
10113 break;
10114 }
10115
10116 // If the user is one of our immediate successors, and if that successor
10117 // only has us as a predecessors (we'd have to split the critical edge
10118 // otherwise), we can keep going.
10119 if (UserIsSuccessor && !isa<PHINode>(I->use_back()) &&
10120 next(pred_begin(UserParent)) == pred_end(UserParent))
10121 // Okay, the CFG is simple enough, try to sink this instruction.
10122 Changed |= TryToSinkInstruction(I, UserParent);
10123 }
10124 }
10125
Chris Lattnerca081252001-12-14 16:52:21 +000010126 // Now that we have an instruction, try combining it to simplify it...
Chris Lattnerae7a0d32002-08-02 19:29:35 +000010127 if (Instruction *Result = visit(*I)) {
Chris Lattner0b18c1d2002-05-10 15:38:35 +000010128 ++NumCombined;
Chris Lattner260ab202002-04-18 17:39:14 +000010129 // Should we replace the old instruction with a new one?
Chris Lattner053c0932002-05-14 15:24:07 +000010130 if (Result != I) {
Bill Wendling5dbf43c2006-11-26 09:46:52 +000010131 DOUT << "IC: Old = " << *I
10132 << " New = " << *Result;
Chris Lattner7d2a5392004-03-13 23:54:27 +000010133
Chris Lattner396dbfe2004-06-09 05:08:07 +000010134 // Everything uses the new instruction now.
10135 I->replaceAllUsesWith(Result);
10136
10137 // Push the new instruction and any users onto the worklist.
Chris Lattnerb15e2b12007-03-02 21:28:56 +000010138 AddToWorkList(Result);
Chris Lattner396dbfe2004-06-09 05:08:07 +000010139 AddUsersToWorkList(*Result);
Chris Lattnere8ed4ef2003-10-06 17:11:01 +000010140
Chris Lattner6e0123b2007-02-11 01:23:03 +000010141 // Move the name to the new instruction first.
10142 Result->takeName(I);
Chris Lattnere8ed4ef2003-10-06 17:11:01 +000010143
10144 // Insert the new instruction into the basic block...
10145 BasicBlock *InstParent = I->getParent();
Chris Lattner7515cab2004-11-14 19:13:23 +000010146 BasicBlock::iterator InsertPos = I;
10147
10148 if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
10149 while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
10150 ++InsertPos;
10151
10152 InstParent->getInstList().insert(InsertPos, Result);
Chris Lattnere8ed4ef2003-10-06 17:11:01 +000010153
Chris Lattner63d75af2004-05-01 23:27:23 +000010154 // Make sure that we reprocess all operands now that we reduced their
10155 // use counts.
Chris Lattnerb15e2b12007-03-02 21:28:56 +000010156 AddUsesToWorkList(*I);
Chris Lattnerb643a9e2004-05-01 23:19:52 +000010157
Chris Lattner396dbfe2004-06-09 05:08:07 +000010158 // Instructions can end up on the worklist more than once. Make sure
10159 // we do not process an instruction that has been deleted.
Chris Lattnerb15e2b12007-03-02 21:28:56 +000010160 RemoveFromWorkList(I);
Chris Lattnere8ed4ef2003-10-06 17:11:01 +000010161
10162 // Erase the old instruction.
10163 InstParent->getInstList().erase(I);
Chris Lattner113f4f42002-06-25 16:13:24 +000010164 } else {
Bill Wendling5dbf43c2006-11-26 09:46:52 +000010165 DOUT << "IC: MOD = " << *I;
Chris Lattner7d2a5392004-03-13 23:54:27 +000010166
Chris Lattnerae7a0d32002-08-02 19:29:35 +000010167 // If the instruction was modified, it's possible that it is now dead.
10168 // if so, remove it.
Chris Lattner63d75af2004-05-01 23:27:23 +000010169 if (isInstructionTriviallyDead(I)) {
10170 // Make sure we process all operands now that we are reducing their
10171 // use counts.
Chris Lattner960a5432007-03-03 02:04:50 +000010172 AddUsesToWorkList(*I);
Misha Brukmanb1c93172005-04-21 23:48:37 +000010173
Chris Lattner63d75af2004-05-01 23:27:23 +000010174 // Instructions may end up in the worklist more than once. Erase all
Robert Bocchinoa8352962006-01-13 22:48:06 +000010175 // occurrences of this instruction.
Chris Lattnerb15e2b12007-03-02 21:28:56 +000010176 RemoveFromWorkList(I);
Chris Lattner31f486c2005-01-31 05:36:43 +000010177 I->eraseFromParent();
Chris Lattner396dbfe2004-06-09 05:08:07 +000010178 } else {
Chris Lattner960a5432007-03-03 02:04:50 +000010179 AddToWorkList(I);
10180 AddUsersToWorkList(*I);
Chris Lattnerae7a0d32002-08-02 19:29:35 +000010181 }
Chris Lattner053c0932002-05-14 15:24:07 +000010182 }
Chris Lattner260ab202002-04-18 17:39:14 +000010183 Changed = true;
Chris Lattnerca081252001-12-14 16:52:21 +000010184 }
10185 }
10186
Chris Lattner960a5432007-03-03 02:04:50 +000010187 assert(WorklistMap.empty() && "Worklist empty, but map not?");
Chris Lattner260ab202002-04-18 17:39:14 +000010188 return Changed;
Chris Lattner04805fa2002-02-26 21:46:54 +000010189}
10190
Chris Lattner960a5432007-03-03 02:04:50 +000010191
10192bool InstCombiner::runOnFunction(Function &F) {
Chris Lattner8258b442007-03-04 04:27:24 +000010193 MustPreserveLCSSA = mustPreserveAnalysisID(LCSSAID);
10194
Chris Lattner960a5432007-03-03 02:04:50 +000010195 bool EverMadeChange = false;
10196
10197 // Iterate while there is work to do.
10198 unsigned Iteration = 0;
10199 while (DoOneIteration(F, Iteration++))
10200 EverMadeChange = true;
10201 return EverMadeChange;
10202}
10203
Brian Gaeke38b79e82004-07-27 17:43:21 +000010204FunctionPass *llvm::createInstructionCombiningPass() {
Chris Lattner260ab202002-04-18 17:39:14 +000010205 return new InstCombiner();
Chris Lattner04805fa2002-02-26 21:46:54 +000010206}
Brian Gaeke960707c2003-11-11 22:41:34 +000010207