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Chris Lattnere6794492002-08-12 21:17:25 +00001//===- InstructionCombining.cpp - Combine multiple instructions -----------===//
John Criswell482202a2003-10-20 19:43:21 +00002//
3// 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.
7//
8//===----------------------------------------------------------------------===//
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:
15// %Y = add int 1, %X
16// %Z = add int 1, %Y
17// into:
18// %Z = add int 2, %X
19//
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.
Chris Lattnerbfb1d032003-07-23 21:41:57 +000027// 3. SetCC instructions are converted from <,>,<=,>= to ==,!= if possible
28// 4. All SetCC 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 Lattnerbfb1d032003-07-23 21:41:57 +000032// N. This list is incomplete
33//
Chris Lattnerca081252001-12-14 16:52:21 +000034//===----------------------------------------------------------------------===//
35
Chris Lattnerb4cfa7f2002-05-07 20:03:00 +000036#include "llvm/Transforms/Scalar.h"
Chris Lattner471bd762003-05-22 19:07:21 +000037#include "llvm/Instructions.h"
Chris Lattner04805fa2002-02-26 21:46:54 +000038#include "llvm/Pass.h"
Chris Lattner34428442003-05-27 16:40:51 +000039#include "llvm/Constants.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 Lattnerf4ad1652003-11-02 05:57:39 +000042#include "llvm/Target/TargetData.h"
43#include "llvm/Transforms/Utils/BasicBlockUtils.h"
44#include "llvm/Transforms/Utils/Local.h"
Chris Lattner60a65912002-02-12 21:07:25 +000045#include "llvm/Support/InstIterator.h"
Chris Lattner260ab202002-04-18 17:39:14 +000046#include "llvm/Support/InstVisitor.h"
Chris Lattner970c33a2003-06-19 17:00:31 +000047#include "llvm/Support/CallSite.h"
Chris Lattnerbf3a0992002-10-01 22:38:41 +000048#include "Support/Statistic.h"
Chris Lattner053c0932002-05-14 15:24:07 +000049#include <algorithm>
Chris Lattner8427bff2003-12-07 01:24:23 +000050using namespace llvm;
Brian Gaeke960707c2003-11-11 22:41:34 +000051
Chris Lattner260ab202002-04-18 17:39:14 +000052namespace {
Chris Lattnerbf3a0992002-10-01 22:38:41 +000053 Statistic<> NumCombined ("instcombine", "Number of insts combined");
54 Statistic<> NumConstProp("instcombine", "Number of constant folds");
55 Statistic<> NumDeadInst ("instcombine", "Number of dead inst eliminated");
56
Chris Lattnerc8e66542002-04-27 06:56:12 +000057 class InstCombiner : public FunctionPass,
Chris Lattner260ab202002-04-18 17:39:14 +000058 public InstVisitor<InstCombiner, Instruction*> {
59 // Worklist of all of the instructions that need to be simplified.
60 std::vector<Instruction*> WorkList;
Chris Lattnerf4ad1652003-11-02 05:57:39 +000061 TargetData *TD;
Chris Lattner260ab202002-04-18 17:39:14 +000062
Chris Lattner113f4f42002-06-25 16:13:24 +000063 void AddUsesToWorkList(Instruction &I) {
Chris Lattner260ab202002-04-18 17:39:14 +000064 // The instruction was simplified, add all users of the instruction to
65 // the work lists because they might get more simplified now...
66 //
Chris Lattner113f4f42002-06-25 16:13:24 +000067 for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
Chris Lattner260ab202002-04-18 17:39:14 +000068 UI != UE; ++UI)
69 WorkList.push_back(cast<Instruction>(*UI));
70 }
71
Chris Lattner99f48c62002-09-02 04:59:56 +000072 // removeFromWorkList - remove all instances of I from the worklist.
73 void removeFromWorkList(Instruction *I);
Chris Lattner260ab202002-04-18 17:39:14 +000074 public:
Chris Lattner113f4f42002-06-25 16:13:24 +000075 virtual bool runOnFunction(Function &F);
Chris Lattner260ab202002-04-18 17:39:14 +000076
Chris Lattnerf12cc842002-04-28 21:27:06 +000077 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
Chris Lattnerf4ad1652003-11-02 05:57:39 +000078 AU.addRequired<TargetData>();
Chris Lattner820d9712002-10-21 20:00:28 +000079 AU.setPreservesCFG();
Chris Lattnerf12cc842002-04-28 21:27:06 +000080 }
81
Chris Lattner260ab202002-04-18 17:39:14 +000082 // Visitation implementation - Implement instruction combining for different
83 // instruction types. The semantics are as follows:
84 // Return Value:
85 // null - No change was made
Chris Lattnere6794492002-08-12 21:17:25 +000086 // I - Change was made, I is still valid, I may be dead though
Chris Lattner260ab202002-04-18 17:39:14 +000087 // otherwise - Change was made, replace I with returned instruction
88 //
Chris Lattner113f4f42002-06-25 16:13:24 +000089 Instruction *visitAdd(BinaryOperator &I);
90 Instruction *visitSub(BinaryOperator &I);
91 Instruction *visitMul(BinaryOperator &I);
92 Instruction *visitDiv(BinaryOperator &I);
93 Instruction *visitRem(BinaryOperator &I);
94 Instruction *visitAnd(BinaryOperator &I);
95 Instruction *visitOr (BinaryOperator &I);
96 Instruction *visitXor(BinaryOperator &I);
97 Instruction *visitSetCondInst(BinaryOperator &I);
Chris Lattnere8d6c602003-03-10 19:16:08 +000098 Instruction *visitShiftInst(ShiftInst &I);
Chris Lattner113f4f42002-06-25 16:13:24 +000099 Instruction *visitCastInst(CastInst &CI);
Chris Lattner970c33a2003-06-19 17:00:31 +0000100 Instruction *visitCallInst(CallInst &CI);
101 Instruction *visitInvokeInst(InvokeInst &II);
Chris Lattner113f4f42002-06-25 16:13:24 +0000102 Instruction *visitPHINode(PHINode &PN);
103 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
Chris Lattner1085bdf2002-11-04 16:18:53 +0000104 Instruction *visitAllocationInst(AllocationInst &AI);
Chris Lattner8427bff2003-12-07 01:24:23 +0000105 Instruction *visitFreeInst(FreeInst &FI);
Chris Lattner0f1d8a32003-06-26 05:06:25 +0000106 Instruction *visitLoadInst(LoadInst &LI);
Chris Lattner9eef8a72003-06-04 04:46:00 +0000107 Instruction *visitBranchInst(BranchInst &BI);
Chris Lattner260ab202002-04-18 17:39:14 +0000108
109 // visitInstruction - Specify what to return for unhandled instructions...
Chris Lattner113f4f42002-06-25 16:13:24 +0000110 Instruction *visitInstruction(Instruction &I) { return 0; }
Chris Lattner6d14f2a2002-08-09 23:47:40 +0000111
Chris Lattner970c33a2003-06-19 17:00:31 +0000112 private:
Chris Lattneraec3d942003-10-07 22:32:43 +0000113 Instruction *visitCallSite(CallSite CS);
Chris Lattner970c33a2003-06-19 17:00:31 +0000114 bool transformConstExprCastCall(CallSite CS);
115
Chris Lattner6d14f2a2002-08-09 23:47:40 +0000116 // InsertNewInstBefore - insert an instruction New before instruction Old
117 // in the program. Add the new instruction to the worklist.
118 //
Chris Lattnere79e8542004-02-23 06:38:22 +0000119 Value *InsertNewInstBefore(Instruction *New, Instruction &Old) {
Chris Lattner65217ff2002-08-23 18:32:43 +0000120 assert(New && New->getParent() == 0 &&
121 "New instruction already inserted into a basic block!");
Chris Lattner6d14f2a2002-08-09 23:47:40 +0000122 BasicBlock *BB = Old.getParent();
123 BB->getInstList().insert(&Old, New); // Insert inst
124 WorkList.push_back(New); // Add to worklist
Chris Lattnere79e8542004-02-23 06:38:22 +0000125 return New;
Chris Lattner6d14f2a2002-08-09 23:47:40 +0000126 }
127
Chris Lattner3ac7c262003-08-13 20:16:26 +0000128 public:
Chris Lattner6d14f2a2002-08-09 23:47:40 +0000129 // ReplaceInstUsesWith - This method is to be used when an instruction is
130 // found to be dead, replacable with another preexisting expression. Here
131 // we add all uses of I to the worklist, replace all uses of I with the new
132 // value, then return I, so that the inst combiner will know that I was
133 // modified.
134 //
135 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
136 AddUsesToWorkList(I); // Add all modified instrs to worklist
137 I.replaceAllUsesWith(V);
138 return &I;
139 }
Chris Lattner3ac7c262003-08-13 20:16:26 +0000140 private:
Chris Lattnerdfae8be2003-07-24 17:35:25 +0000141 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
142 /// InsertBefore instruction. This is specialized a bit to avoid inserting
143 /// casts that are known to not do anything...
144 ///
145 Value *InsertOperandCastBefore(Value *V, const Type *DestTy,
146 Instruction *InsertBefore);
147
Chris Lattner7fb29e12003-03-11 00:12:48 +0000148 // SimplifyCommutative - This performs a few simplifications for commutative
149 // operators...
150 bool SimplifyCommutative(BinaryOperator &I);
Chris Lattnerba1cb382003-09-19 17:17:26 +0000151
152 Instruction *OptAndOp(Instruction *Op, ConstantIntegral *OpRHS,
153 ConstantIntegral *AndRHS, BinaryOperator &TheAnd);
Chris Lattner260ab202002-04-18 17:39:14 +0000154 };
Chris Lattnerb28b6802002-07-23 18:06:35 +0000155
Chris Lattnerc8b70922002-07-26 21:12:46 +0000156 RegisterOpt<InstCombiner> X("instcombine", "Combine redundant instructions");
Chris Lattner260ab202002-04-18 17:39:14 +0000157}
158
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000159// getComplexity: Assign a complexity or rank value to LLVM Values...
160// 0 -> Constant, 1 -> Other, 2 -> Argument, 2 -> Unary, 3 -> OtherInst
161static unsigned getComplexity(Value *V) {
162 if (isa<Instruction>(V)) {
163 if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V))
164 return 2;
165 return 3;
166 }
167 if (isa<Argument>(V)) return 2;
168 return isa<Constant>(V) ? 0 : 1;
169}
Chris Lattner260ab202002-04-18 17:39:14 +0000170
Chris Lattner7fb29e12003-03-11 00:12:48 +0000171// isOnlyUse - Return true if this instruction will be deleted if we stop using
172// it.
173static bool isOnlyUse(Value *V) {
Chris Lattnerf95d9b92003-10-15 16:48:29 +0000174 return V->hasOneUse() || isa<Constant>(V);
Chris Lattner7fb29e12003-03-11 00:12:48 +0000175}
176
Chris Lattnere79e8542004-02-23 06:38:22 +0000177// getSignedIntegralType - Given an unsigned integral type, return the signed
178// version of it that has the same size.
179static const Type *getSignedIntegralType(const Type *Ty) {
180 switch (Ty->getPrimitiveID()) {
181 default: assert(0 && "Invalid unsigned integer type!"); abort();
182 case Type::UByteTyID: return Type::SByteTy;
183 case Type::UShortTyID: return Type::ShortTy;
184 case Type::UIntTyID: return Type::IntTy;
185 case Type::ULongTyID: return Type::LongTy;
186 }
187}
188
189// getPromotedType - Return the specified type promoted as it would be to pass
190// though a va_arg area...
191static const Type *getPromotedType(const Type *Ty) {
192 switch (Ty->getPrimitiveID()) {
193 case Type::SByteTyID:
194 case Type::ShortTyID: return Type::IntTy;
195 case Type::UByteTyID:
196 case Type::UShortTyID: return Type::UIntTy;
197 case Type::FloatTyID: return Type::DoubleTy;
198 default: return Ty;
199 }
200}
201
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000202// SimplifyCommutative - This performs a few simplifications for commutative
203// operators:
Chris Lattner260ab202002-04-18 17:39:14 +0000204//
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000205// 1. Order operands such that they are listed from right (least complex) to
206// left (most complex). This puts constants before unary operators before
207// binary operators.
208//
Chris Lattner7fb29e12003-03-11 00:12:48 +0000209// 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
210// 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000211//
Chris Lattner7fb29e12003-03-11 00:12:48 +0000212bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000213 bool Changed = false;
214 if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
215 Changed = !I.swapOperands();
216
217 if (!I.isAssociative()) return Changed;
218 Instruction::BinaryOps Opcode = I.getOpcode();
Chris Lattner7fb29e12003-03-11 00:12:48 +0000219 if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
220 if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
221 if (isa<Constant>(I.getOperand(1))) {
Chris Lattner34428442003-05-27 16:40:51 +0000222 Constant *Folded = ConstantExpr::get(I.getOpcode(),
223 cast<Constant>(I.getOperand(1)),
224 cast<Constant>(Op->getOperand(1)));
Chris Lattner7fb29e12003-03-11 00:12:48 +0000225 I.setOperand(0, Op->getOperand(0));
226 I.setOperand(1, Folded);
227 return true;
228 } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
229 if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
230 isOnlyUse(Op) && isOnlyUse(Op1)) {
231 Constant *C1 = cast<Constant>(Op->getOperand(1));
232 Constant *C2 = cast<Constant>(Op1->getOperand(1));
233
234 // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
Chris Lattner34428442003-05-27 16:40:51 +0000235 Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
Chris Lattner7fb29e12003-03-11 00:12:48 +0000236 Instruction *New = BinaryOperator::create(Opcode, Op->getOperand(0),
237 Op1->getOperand(0),
238 Op1->getName(), &I);
239 WorkList.push_back(New);
240 I.setOperand(0, New);
241 I.setOperand(1, Folded);
242 return true;
243 }
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000244 }
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000245 return Changed;
Chris Lattner260ab202002-04-18 17:39:14 +0000246}
Chris Lattnerca081252001-12-14 16:52:21 +0000247
Chris Lattnerbb74e222003-03-10 23:06:50 +0000248// dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
249// if the LHS is a constant zero (which is the 'negate' form).
Chris Lattner9fa53de2002-05-06 16:49:18 +0000250//
Chris Lattnerbb74e222003-03-10 23:06:50 +0000251static inline Value *dyn_castNegVal(Value *V) {
252 if (BinaryOperator::isNeg(V))
253 return BinaryOperator::getNegArgument(cast<BinaryOperator>(V));
254
Chris Lattner9244df62003-04-30 22:19:10 +0000255 // Constants can be considered to be negated values if they can be folded...
256 if (Constant *C = dyn_cast<Constant>(V))
Chris Lattner34428442003-05-27 16:40:51 +0000257 return ConstantExpr::get(Instruction::Sub,
258 Constant::getNullValue(V->getType()), C);
Chris Lattnerbb74e222003-03-10 23:06:50 +0000259 return 0;
Chris Lattner9fa53de2002-05-06 16:49:18 +0000260}
261
Chris Lattnerc1e7cc02004-01-12 19:35:11 +0000262static Constant *NotConstant(Constant *C) {
263 return ConstantExpr::get(Instruction::Xor, C,
264 ConstantIntegral::getAllOnesValue(C->getType()));
265}
266
Chris Lattnerbb74e222003-03-10 23:06:50 +0000267static inline Value *dyn_castNotVal(Value *V) {
268 if (BinaryOperator::isNot(V))
269 return BinaryOperator::getNotArgument(cast<BinaryOperator>(V));
270
271 // Constants can be considered to be not'ed values...
Chris Lattnerdd65d862003-04-30 22:34:06 +0000272 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(V))
Chris Lattnerc1e7cc02004-01-12 19:35:11 +0000273 return NotConstant(C);
Chris Lattnerbb74e222003-03-10 23:06:50 +0000274 return 0;
275}
276
Chris Lattner7fb29e12003-03-11 00:12:48 +0000277// dyn_castFoldableMul - If this value is a multiply that can be folded into
278// other computations (because it has a constant operand), return the
279// non-constant operand of the multiply.
280//
281static inline Value *dyn_castFoldableMul(Value *V) {
Chris Lattnerf95d9b92003-10-15 16:48:29 +0000282 if (V->hasOneUse() && V->getType()->isInteger())
Chris Lattner7fb29e12003-03-11 00:12:48 +0000283 if (Instruction *I = dyn_cast<Instruction>(V))
284 if (I->getOpcode() == Instruction::Mul)
285 if (isa<Constant>(I->getOperand(1)))
286 return I->getOperand(0);
287 return 0;
Chris Lattner3082c5a2003-02-18 19:28:33 +0000288}
Chris Lattner31ae8632002-08-14 17:51:49 +0000289
Chris Lattner7fb29e12003-03-11 00:12:48 +0000290// dyn_castMaskingAnd - If this value is an And instruction masking a value with
291// a constant, return the constant being anded with.
292//
Chris Lattner01d56392003-08-12 19:17:27 +0000293template<class ValueType>
294static inline Constant *dyn_castMaskingAnd(ValueType *V) {
Chris Lattner7fb29e12003-03-11 00:12:48 +0000295 if (Instruction *I = dyn_cast<Instruction>(V))
296 if (I->getOpcode() == Instruction::And)
297 return dyn_cast<Constant>(I->getOperand(1));
298
299 // If this is a constant, it acts just like we were masking with it.
300 return dyn_cast<Constant>(V);
301}
Chris Lattner3082c5a2003-02-18 19:28:33 +0000302
303// Log2 - Calculate the log base 2 for the specified value if it is exactly a
304// power of 2.
305static unsigned Log2(uint64_t Val) {
306 assert(Val > 1 && "Values 0 and 1 should be handled elsewhere!");
307 unsigned Count = 0;
308 while (Val != 1) {
309 if (Val & 1) return 0; // Multiple bits set?
310 Val >>= 1;
311 ++Count;
312 }
313 return Count;
Chris Lattner31ae8632002-08-14 17:51:49 +0000314}
315
Chris Lattnerb8b97502003-08-13 19:01:45 +0000316
317/// AssociativeOpt - Perform an optimization on an associative operator. This
318/// function is designed to check a chain of associative operators for a
319/// potential to apply a certain optimization. Since the optimization may be
320/// applicable if the expression was reassociated, this checks the chain, then
321/// reassociates the expression as necessary to expose the optimization
322/// opportunity. This makes use of a special Functor, which must define
323/// 'shouldApply' and 'apply' methods.
324///
325template<typename Functor>
326Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
327 unsigned Opcode = Root.getOpcode();
328 Value *LHS = Root.getOperand(0);
329
330 // Quick check, see if the immediate LHS matches...
331 if (F.shouldApply(LHS))
332 return F.apply(Root);
333
334 // Otherwise, if the LHS is not of the same opcode as the root, return.
335 Instruction *LHSI = dyn_cast<Instruction>(LHS);
Chris Lattnerf95d9b92003-10-15 16:48:29 +0000336 while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
Chris Lattnerb8b97502003-08-13 19:01:45 +0000337 // Should we apply this transform to the RHS?
338 bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
339
340 // If not to the RHS, check to see if we should apply to the LHS...
341 if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
342 cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
343 ShouldApply = true;
344 }
345
346 // If the functor wants to apply the optimization to the RHS of LHSI,
347 // reassociate the expression from ((? op A) op B) to (? op (A op B))
348 if (ShouldApply) {
349 BasicBlock *BB = Root.getParent();
350 // All of the instructions have a single use and have no side-effects,
351 // because of this, we can pull them all into the current basic block.
352 if (LHSI->getParent() != BB) {
353 // Move all of the instructions from root to LHSI into the current
354 // block.
355 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
356 Instruction *LastUse = &Root;
357 while (TmpLHSI->getParent() == BB) {
358 LastUse = TmpLHSI;
359 TmpLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
360 }
361
362 // Loop over all of the instructions in other blocks, moving them into
363 // the current one.
364 Value *TmpLHS = TmpLHSI;
365 do {
366 TmpLHSI = cast<Instruction>(TmpLHS);
367 // Remove from current block...
368 TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
369 // Insert before the last instruction...
370 BB->getInstList().insert(LastUse, TmpLHSI);
371 TmpLHS = TmpLHSI->getOperand(0);
372 } while (TmpLHSI != LHSI);
373 }
374
375 // Now all of the instructions are in the current basic block, go ahead
376 // and perform the reassociation.
377 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
378
379 // First move the selected RHS to the LHS of the root...
380 Root.setOperand(0, LHSI->getOperand(1));
381
382 // Make what used to be the LHS of the root be the user of the root...
383 Value *ExtraOperand = TmpLHSI->getOperand(1);
384 Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
385 TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
386 BB->getInstList().remove(&Root); // Remove root from the BB
387 BB->getInstList().insert(TmpLHSI, &Root); // Insert root before TmpLHSI
388
389 // Now propagate the ExtraOperand down the chain of instructions until we
390 // get to LHSI.
391 while (TmpLHSI != LHSI) {
392 Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
393 Value *NextOp = NextLHSI->getOperand(1);
394 NextLHSI->setOperand(1, ExtraOperand);
395 TmpLHSI = NextLHSI;
396 ExtraOperand = NextOp;
397 }
398
399 // Now that the instructions are reassociated, have the functor perform
400 // the transformation...
401 return F.apply(Root);
402 }
403
404 LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
405 }
406 return 0;
407}
408
409
410// AddRHS - Implements: X + X --> X << 1
411struct AddRHS {
412 Value *RHS;
413 AddRHS(Value *rhs) : RHS(rhs) {}
414 bool shouldApply(Value *LHS) const { return LHS == RHS; }
415 Instruction *apply(BinaryOperator &Add) const {
416 return new ShiftInst(Instruction::Shl, Add.getOperand(0),
417 ConstantInt::get(Type::UByteTy, 1));
418 }
419};
420
421// AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
422// iff C1&C2 == 0
423struct AddMaskingAnd {
424 Constant *C2;
425 AddMaskingAnd(Constant *c) : C2(c) {}
426 bool shouldApply(Value *LHS) const {
427 if (Constant *C1 = dyn_castMaskingAnd(LHS))
428 return ConstantExpr::get(Instruction::And, C1, C2)->isNullValue();
429 return false;
430 }
431 Instruction *apply(BinaryOperator &Add) const {
432 return BinaryOperator::create(Instruction::Or, Add.getOperand(0),
433 Add.getOperand(1));
434 }
435};
436
437
438
Chris Lattner113f4f42002-06-25 16:13:24 +0000439Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000440 bool Changed = SimplifyCommutative(I);
Chris Lattner113f4f42002-06-25 16:13:24 +0000441 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
Chris Lattner9fa53de2002-05-06 16:49:18 +0000442
Chris Lattnerb8b97502003-08-13 19:01:45 +0000443 // X + 0 --> X
Chris Lattnere6794492002-08-12 21:17:25 +0000444 if (RHS == Constant::getNullValue(I.getType()))
445 return ReplaceInstUsesWith(I, LHS);
Chris Lattner9fa53de2002-05-06 16:49:18 +0000446
Chris Lattnerb8b97502003-08-13 19:01:45 +0000447 // X + X --> X << 1
448 if (I.getType()->isInteger())
449 if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
Chris Lattnerede3fe02003-08-13 04:18:28 +0000450
Chris Lattner147e9752002-05-08 22:46:53 +0000451 // -A + B --> B - A
Chris Lattnerbb74e222003-03-10 23:06:50 +0000452 if (Value *V = dyn_castNegVal(LHS))
Chris Lattner147e9752002-05-08 22:46:53 +0000453 return BinaryOperator::create(Instruction::Sub, RHS, V);
Chris Lattner9fa53de2002-05-06 16:49:18 +0000454
455 // A + -B --> A - B
Chris Lattnerbb74e222003-03-10 23:06:50 +0000456 if (!isa<Constant>(RHS))
457 if (Value *V = dyn_castNegVal(RHS))
458 return BinaryOperator::create(Instruction::Sub, LHS, V);
Chris Lattner260ab202002-04-18 17:39:14 +0000459
Chris Lattner57c8d992003-02-18 19:57:07 +0000460 // X*C + X --> X * (C+1)
461 if (dyn_castFoldableMul(LHS) == RHS) {
Chris Lattner34428442003-05-27 16:40:51 +0000462 Constant *CP1 =
463 ConstantExpr::get(Instruction::Add,
464 cast<Constant>(cast<Instruction>(LHS)->getOperand(1)),
465 ConstantInt::get(I.getType(), 1));
Chris Lattner57c8d992003-02-18 19:57:07 +0000466 return BinaryOperator::create(Instruction::Mul, RHS, CP1);
467 }
468
469 // X + X*C --> X * (C+1)
470 if (dyn_castFoldableMul(RHS) == LHS) {
Chris Lattner34428442003-05-27 16:40:51 +0000471 Constant *CP1 =
472 ConstantExpr::get(Instruction::Add,
473 cast<Constant>(cast<Instruction>(RHS)->getOperand(1)),
474 ConstantInt::get(I.getType(), 1));
Chris Lattner57c8d992003-02-18 19:57:07 +0000475 return BinaryOperator::create(Instruction::Mul, LHS, CP1);
476 }
477
Chris Lattnerb8b97502003-08-13 19:01:45 +0000478 // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
479 if (Constant *C2 = dyn_castMaskingAnd(RHS))
480 if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R;
Chris Lattner7fb29e12003-03-11 00:12:48 +0000481
Chris Lattnerb9cde762003-10-02 15:11:26 +0000482 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
483 if (Instruction *ILHS = dyn_cast<Instruction>(LHS)) {
484 switch (ILHS->getOpcode()) {
485 case Instruction::Xor:
486 // ~X + C --> (C-1) - X
487 if (ConstantInt *XorRHS = dyn_cast<ConstantInt>(ILHS->getOperand(1)))
488 if (XorRHS->isAllOnesValue())
489 return BinaryOperator::create(Instruction::Sub,
Chris Lattnerc1e7cc02004-01-12 19:35:11 +0000490 ConstantExpr::get(Instruction::Sub,
491 CRHS, ConstantInt::get(I.getType(), 1)),
Chris Lattnerb9cde762003-10-02 15:11:26 +0000492 ILHS->getOperand(0));
493 break;
494 default: break;
495 }
496 }
497 }
498
Chris Lattner113f4f42002-06-25 16:13:24 +0000499 return Changed ? &I : 0;
Chris Lattner260ab202002-04-18 17:39:14 +0000500}
501
Chris Lattnerbdb0ce02003-07-22 21:46:59 +0000502// isSignBit - Return true if the value represented by the constant only has the
503// highest order bit set.
504static bool isSignBit(ConstantInt *CI) {
505 unsigned NumBits = CI->getType()->getPrimitiveSize()*8;
506 return (CI->getRawValue() & ~(-1LL << NumBits)) == (1ULL << (NumBits-1));
507}
508
Chris Lattnerdfae8be2003-07-24 17:35:25 +0000509static unsigned getTypeSizeInBits(const Type *Ty) {
510 return Ty == Type::BoolTy ? 1 : Ty->getPrimitiveSize()*8;
511}
512
Chris Lattner113f4f42002-06-25 16:13:24 +0000513Instruction *InstCombiner::visitSub(BinaryOperator &I) {
Chris Lattner113f4f42002-06-25 16:13:24 +0000514 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
Chris Lattnerf4cdbf32002-05-06 16:14:14 +0000515
Chris Lattnere6794492002-08-12 21:17:25 +0000516 if (Op0 == Op1) // sub X, X -> 0
517 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
Chris Lattner260ab202002-04-18 17:39:14 +0000518
Chris Lattnere6794492002-08-12 21:17:25 +0000519 // If this is a 'B = x-(-A)', change to B = x+A...
Chris Lattnerbb74e222003-03-10 23:06:50 +0000520 if (Value *V = dyn_castNegVal(Op1))
Chris Lattner147e9752002-05-08 22:46:53 +0000521 return BinaryOperator::create(Instruction::Add, Op0, V);
Chris Lattner9fa53de2002-05-06 16:49:18 +0000522
Chris Lattner8f2f5982003-11-05 01:06:05 +0000523 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
524 // Replace (-1 - A) with (~A)...
Chris Lattner3082c5a2003-02-18 19:28:33 +0000525 if (C->isAllOnesValue())
526 return BinaryOperator::createNot(Op1);
Chris Lattnerad3c4952002-05-09 01:29:19 +0000527
Chris Lattner8f2f5982003-11-05 01:06:05 +0000528 // C - ~X == X + (1+C)
529 if (BinaryOperator::isNot(Op1))
530 return BinaryOperator::create(Instruction::Add,
Chris Lattnerc1e7cc02004-01-12 19:35:11 +0000531 BinaryOperator::getNotArgument(cast<BinaryOperator>(Op1)),
532 ConstantExpr::get(Instruction::Add, C,
533 ConstantInt::get(I.getType(), 1)));
Chris Lattner8f2f5982003-11-05 01:06:05 +0000534 }
535
Chris Lattner3082c5a2003-02-18 19:28:33 +0000536 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1))
Chris Lattnerf95d9b92003-10-15 16:48:29 +0000537 if (Op1I->hasOneUse()) {
Chris Lattner3082c5a2003-02-18 19:28:33 +0000538 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
539 // is not used by anyone else...
540 //
Chris Lattnerc2f0aa52004-02-02 20:09:56 +0000541 if (Op1I->getOpcode() == Instruction::Sub &&
542 !Op1I->getType()->isFloatingPoint()) {
Chris Lattner3082c5a2003-02-18 19:28:33 +0000543 // Swap the two operands of the subexpr...
544 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
545 Op1I->setOperand(0, IIOp1);
546 Op1I->setOperand(1, IIOp0);
547
548 // Create the new top level add instruction...
549 return BinaryOperator::create(Instruction::Add, Op0, Op1);
550 }
551
552 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
553 //
554 if (Op1I->getOpcode() == Instruction::And &&
555 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
556 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
557
558 Instruction *NewNot = BinaryOperator::createNot(OtherOp, "B.not", &I);
559 return BinaryOperator::create(Instruction::And, Op0, NewNot);
560 }
Chris Lattner57c8d992003-02-18 19:57:07 +0000561
562 // X - X*C --> X * (1-C)
563 if (dyn_castFoldableMul(Op1I) == Op0) {
Chris Lattner34428442003-05-27 16:40:51 +0000564 Constant *CP1 =
565 ConstantExpr::get(Instruction::Sub,
566 ConstantInt::get(I.getType(), 1),
567 cast<Constant>(cast<Instruction>(Op1)->getOperand(1)));
Chris Lattner57c8d992003-02-18 19:57:07 +0000568 assert(CP1 && "Couldn't constant fold 1-C?");
569 return BinaryOperator::create(Instruction::Mul, Op0, CP1);
570 }
Chris Lattnerad3c4952002-05-09 01:29:19 +0000571 }
Chris Lattner3082c5a2003-02-18 19:28:33 +0000572
Chris Lattner57c8d992003-02-18 19:57:07 +0000573 // X*C - X --> X * (C-1)
574 if (dyn_castFoldableMul(Op0) == Op1) {
Chris Lattner34428442003-05-27 16:40:51 +0000575 Constant *CP1 =
576 ConstantExpr::get(Instruction::Sub,
577 cast<Constant>(cast<Instruction>(Op0)->getOperand(1)),
578 ConstantInt::get(I.getType(), 1));
Chris Lattner57c8d992003-02-18 19:57:07 +0000579 assert(CP1 && "Couldn't constant fold C - 1?");
580 return BinaryOperator::create(Instruction::Mul, Op1, CP1);
581 }
582
Chris Lattnerf4cdbf32002-05-06 16:14:14 +0000583 return 0;
Chris Lattner260ab202002-04-18 17:39:14 +0000584}
585
Chris Lattnere79e8542004-02-23 06:38:22 +0000586/// isSignBitCheck - Given an exploded setcc instruction, return true if it is
587/// really just returns true if the most significant (sign) bit is set.
588static bool isSignBitCheck(unsigned Opcode, Value *LHS, ConstantInt *RHS) {
589 if (RHS->getType()->isSigned()) {
590 // True if source is LHS < 0 or LHS <= -1
591 return Opcode == Instruction::SetLT && RHS->isNullValue() ||
592 Opcode == Instruction::SetLE && RHS->isAllOnesValue();
593 } else {
594 ConstantUInt *RHSC = cast<ConstantUInt>(RHS);
595 // True if source is LHS > 127 or LHS >= 128, where the constants depend on
596 // the size of the integer type.
597 if (Opcode == Instruction::SetGE)
598 return RHSC->getValue() == 1ULL<<(RHS->getType()->getPrimitiveSize()*8-1);
599 if (Opcode == Instruction::SetGT)
600 return RHSC->getValue() ==
601 (1ULL << (RHS->getType()->getPrimitiveSize()*8-1))-1;
602 }
603 return false;
604}
605
Chris Lattner113f4f42002-06-25 16:13:24 +0000606Instruction *InstCombiner::visitMul(BinaryOperator &I) {
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000607 bool Changed = SimplifyCommutative(I);
Chris Lattner3082c5a2003-02-18 19:28:33 +0000608 Value *Op0 = I.getOperand(0);
Chris Lattner260ab202002-04-18 17:39:14 +0000609
Chris Lattnere6794492002-08-12 21:17:25 +0000610 // Simplify mul instructions with a constant RHS...
Chris Lattner3082c5a2003-02-18 19:28:33 +0000611 if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
612 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
Chris Lattnerede3fe02003-08-13 04:18:28 +0000613
614 // ((X << C1)*C2) == (X * (C2 << C1))
615 if (ShiftInst *SI = dyn_cast<ShiftInst>(Op0))
616 if (SI->getOpcode() == Instruction::Shl)
617 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
618 return BinaryOperator::create(Instruction::Mul, SI->getOperand(0),
Chris Lattnerc1e7cc02004-01-12 19:35:11 +0000619 ConstantExpr::get(Instruction::Shl, CI, ShOp));
620
Chris Lattnercce81be2003-09-11 22:24:54 +0000621 if (CI->isNullValue())
622 return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
623 if (CI->equalsInt(1)) // X * 1 == X
624 return ReplaceInstUsesWith(I, Op0);
625 if (CI->isAllOnesValue()) // X * -1 == 0 - X
Chris Lattner35236d82003-06-25 17:09:20 +0000626 return BinaryOperator::createNeg(Op0, I.getName());
Chris Lattner31ba1292002-04-29 22:24:47 +0000627
Chris Lattnercce81be2003-09-11 22:24:54 +0000628 int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue();
Chris Lattner3082c5a2003-02-18 19:28:33 +0000629 if (uint64_t C = Log2(Val)) // Replace X*(2^C) with X << C
630 return new ShiftInst(Instruction::Shl, Op0,
631 ConstantUInt::get(Type::UByteTy, C));
632 } else {
633 ConstantFP *Op1F = cast<ConstantFP>(Op1);
634 if (Op1F->isNullValue())
635 return ReplaceInstUsesWith(I, Op1);
Chris Lattner31ba1292002-04-29 22:24:47 +0000636
Chris Lattner3082c5a2003-02-18 19:28:33 +0000637 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
638 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
639 if (Op1F->getValue() == 1.0)
640 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
641 }
Chris Lattner260ab202002-04-18 17:39:14 +0000642 }
643
Chris Lattner934a64cf2003-03-10 23:23:04 +0000644 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
645 if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
646 return BinaryOperator::create(Instruction::Mul, Op0v, Op1v);
647
Chris Lattner2635b522004-02-23 05:39:21 +0000648 // If one of the operands of the multiply is a cast from a boolean value, then
649 // we know the bool is either zero or one, so this is a 'masking' multiply.
650 // See if we can simplify things based on how the boolean was originally
651 // formed.
652 CastInst *BoolCast = 0;
653 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(0)))
654 if (CI->getOperand(0)->getType() == Type::BoolTy)
655 BoolCast = CI;
656 if (!BoolCast)
657 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(1)))
658 if (CI->getOperand(0)->getType() == Type::BoolTy)
659 BoolCast = CI;
660 if (BoolCast) {
661 if (SetCondInst *SCI = dyn_cast<SetCondInst>(BoolCast->getOperand(0))) {
662 Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
663 const Type *SCOpTy = SCIOp0->getType();
664
Chris Lattnere79e8542004-02-23 06:38:22 +0000665 // If the setcc is true iff the sign bit of X is set, then convert this
666 // multiply into a shift/and combination.
667 if (isa<ConstantInt>(SCIOp1) &&
668 isSignBitCheck(SCI->getOpcode(), SCIOp0, cast<ConstantInt>(SCIOp1))) {
Chris Lattner2635b522004-02-23 05:39:21 +0000669 // Shift the X value right to turn it into "all signbits".
670 Constant *Amt = ConstantUInt::get(Type::UByteTy,
671 SCOpTy->getPrimitiveSize()*8-1);
Chris Lattnere79e8542004-02-23 06:38:22 +0000672 if (SCIOp0->getType()->isUnsigned()) {
673 const Type *NewTy = getSignedIntegralType(SCIOp0->getType());
674 SCIOp0 = InsertNewInstBefore(new CastInst(SCIOp0, NewTy,
675 SCIOp0->getName()), I);
676 }
677
678 Value *V =
679 InsertNewInstBefore(new ShiftInst(Instruction::Shr, SCIOp0, Amt,
680 BoolCast->getOperand(0)->getName()+
681 ".mask"), I);
Chris Lattner2635b522004-02-23 05:39:21 +0000682
683 // If the multiply type is not the same as the source type, sign extend
684 // or truncate to the multiply type.
685 if (I.getType() != V->getType())
Chris Lattnere79e8542004-02-23 06:38:22 +0000686 V = InsertNewInstBefore(new CastInst(V, I.getType(), V->getName()),I);
Chris Lattner2635b522004-02-23 05:39:21 +0000687
688 Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
689 return BinaryOperator::create(Instruction::And, V, OtherOp);
690 }
691 }
692 }
693
Chris Lattner113f4f42002-06-25 16:13:24 +0000694 return Changed ? &I : 0;
Chris Lattner260ab202002-04-18 17:39:14 +0000695}
696
Chris Lattner113f4f42002-06-25 16:13:24 +0000697Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
Chris Lattnerf4cdbf32002-05-06 16:14:14 +0000698 // div X, 1 == X
Chris Lattner3082c5a2003-02-18 19:28:33 +0000699 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) {
Chris Lattnere6794492002-08-12 21:17:25 +0000700 if (RHS->equalsInt(1))
701 return ReplaceInstUsesWith(I, I.getOperand(0));
Chris Lattner3082c5a2003-02-18 19:28:33 +0000702
703 // Check to see if this is an unsigned division with an exact power of 2,
704 // if so, convert to a right shift.
705 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
706 if (uint64_t Val = C->getValue()) // Don't break X / 0
707 if (uint64_t C = Log2(Val))
708 return new ShiftInst(Instruction::Shr, I.getOperand(0),
709 ConstantUInt::get(Type::UByteTy, C));
710 }
711
712 // 0 / X == 0, we don't need to preserve faults!
713 if (ConstantInt *LHS = dyn_cast<ConstantInt>(I.getOperand(0)))
714 if (LHS->equalsInt(0))
715 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
716
Chris Lattnerf4cdbf32002-05-06 16:14:14 +0000717 return 0;
718}
719
720
Chris Lattner113f4f42002-06-25 16:13:24 +0000721Instruction *InstCombiner::visitRem(BinaryOperator &I) {
Chris Lattner3082c5a2003-02-18 19:28:33 +0000722 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) {
723 if (RHS->equalsInt(1)) // X % 1 == 0
724 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
725
726 // Check to see if this is an unsigned remainder with an exact power of 2,
727 // if so, convert to a bitwise and.
728 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
729 if (uint64_t Val = C->getValue()) // Don't break X % 0 (divide by zero)
730 if (Log2(Val))
731 return BinaryOperator::create(Instruction::And, I.getOperand(0),
732 ConstantUInt::get(I.getType(), Val-1));
733 }
734
735 // 0 % X == 0, we don't need to preserve faults!
736 if (ConstantInt *LHS = dyn_cast<ConstantInt>(I.getOperand(0)))
737 if (LHS->equalsInt(0))
Chris Lattnere6794492002-08-12 21:17:25 +0000738 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
739
Chris Lattnerf4cdbf32002-05-06 16:14:14 +0000740 return 0;
741}
742
Chris Lattner6d14f2a2002-08-09 23:47:40 +0000743// isMaxValueMinusOne - return true if this is Max-1
Chris Lattnere6794492002-08-12 21:17:25 +0000744static bool isMaxValueMinusOne(const ConstantInt *C) {
Chris Lattner6d14f2a2002-08-09 23:47:40 +0000745 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) {
746 // Calculate -1 casted to the right type...
747 unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
748 uint64_t Val = ~0ULL; // All ones
749 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
750 return CU->getValue() == Val-1;
751 }
752
753 const ConstantSInt *CS = cast<ConstantSInt>(C);
754
755 // Calculate 0111111111..11111
756 unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
757 int64_t Val = INT64_MAX; // All ones
758 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
759 return CS->getValue() == Val-1;
760}
761
762// isMinValuePlusOne - return true if this is Min+1
Chris Lattnere6794492002-08-12 21:17:25 +0000763static bool isMinValuePlusOne(const ConstantInt *C) {
Chris Lattner6d14f2a2002-08-09 23:47:40 +0000764 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
765 return CU->getValue() == 1;
766
767 const ConstantSInt *CS = cast<ConstantSInt>(C);
768
769 // Calculate 1111111111000000000000
770 unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
771 int64_t Val = -1; // All ones
772 Val <<= TypeBits-1; // Shift over to the right spot
773 return CS->getValue() == Val+1;
774}
775
Chris Lattner3ac7c262003-08-13 20:16:26 +0000776/// getSetCondCode - Encode a setcc opcode into a three bit mask. These bits
777/// are carefully arranged to allow folding of expressions such as:
778///
779/// (A < B) | (A > B) --> (A != B)
780///
781/// Bit value '4' represents that the comparison is true if A > B, bit value '2'
782/// represents that the comparison is true if A == B, and bit value '1' is true
783/// if A < B.
784///
785static unsigned getSetCondCode(const SetCondInst *SCI) {
786 switch (SCI->getOpcode()) {
787 // False -> 0
788 case Instruction::SetGT: return 1;
789 case Instruction::SetEQ: return 2;
790 case Instruction::SetGE: return 3;
791 case Instruction::SetLT: return 4;
792 case Instruction::SetNE: return 5;
793 case Instruction::SetLE: return 6;
794 // True -> 7
795 default:
796 assert(0 && "Invalid SetCC opcode!");
797 return 0;
798 }
799}
800
801/// getSetCCValue - This is the complement of getSetCondCode, which turns an
802/// opcode and two operands into either a constant true or false, or a brand new
803/// SetCC instruction.
804static Value *getSetCCValue(unsigned Opcode, Value *LHS, Value *RHS) {
805 switch (Opcode) {
806 case 0: return ConstantBool::False;
807 case 1: return new SetCondInst(Instruction::SetGT, LHS, RHS);
808 case 2: return new SetCondInst(Instruction::SetEQ, LHS, RHS);
809 case 3: return new SetCondInst(Instruction::SetGE, LHS, RHS);
810 case 4: return new SetCondInst(Instruction::SetLT, LHS, RHS);
811 case 5: return new SetCondInst(Instruction::SetNE, LHS, RHS);
812 case 6: return new SetCondInst(Instruction::SetLE, LHS, RHS);
813 case 7: return ConstantBool::True;
814 default: assert(0 && "Illegal SetCCCode!"); return 0;
815 }
816}
817
818// FoldSetCCLogical - Implements (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
819struct FoldSetCCLogical {
820 InstCombiner &IC;
821 Value *LHS, *RHS;
822 FoldSetCCLogical(InstCombiner &ic, SetCondInst *SCI)
823 : IC(ic), LHS(SCI->getOperand(0)), RHS(SCI->getOperand(1)) {}
824 bool shouldApply(Value *V) const {
825 if (SetCondInst *SCI = dyn_cast<SetCondInst>(V))
826 return (SCI->getOperand(0) == LHS && SCI->getOperand(1) == RHS ||
827 SCI->getOperand(0) == RHS && SCI->getOperand(1) == LHS);
828 return false;
829 }
830 Instruction *apply(BinaryOperator &Log) const {
831 SetCondInst *SCI = cast<SetCondInst>(Log.getOperand(0));
832 if (SCI->getOperand(0) != LHS) {
833 assert(SCI->getOperand(1) == LHS);
834 SCI->swapOperands(); // Swap the LHS and RHS of the SetCC
835 }
836
837 unsigned LHSCode = getSetCondCode(SCI);
838 unsigned RHSCode = getSetCondCode(cast<SetCondInst>(Log.getOperand(1)));
839 unsigned Code;
840 switch (Log.getOpcode()) {
841 case Instruction::And: Code = LHSCode & RHSCode; break;
842 case Instruction::Or: Code = LHSCode | RHSCode; break;
843 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
Chris Lattner2caaaba2003-09-22 20:33:34 +0000844 default: assert(0 && "Illegal logical opcode!"); return 0;
Chris Lattner3ac7c262003-08-13 20:16:26 +0000845 }
846
847 Value *RV = getSetCCValue(Code, LHS, RHS);
848 if (Instruction *I = dyn_cast<Instruction>(RV))
849 return I;
850 // Otherwise, it's a constant boolean value...
851 return IC.ReplaceInstUsesWith(Log, RV);
852 }
853};
854
855
Chris Lattnerba1cb382003-09-19 17:17:26 +0000856// OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
857// the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
858// guaranteed to be either a shift instruction or a binary operator.
859Instruction *InstCombiner::OptAndOp(Instruction *Op,
860 ConstantIntegral *OpRHS,
861 ConstantIntegral *AndRHS,
862 BinaryOperator &TheAnd) {
863 Value *X = Op->getOperand(0);
Chris Lattnerfcf21a72004-01-12 19:47:05 +0000864 Constant *Together = 0;
865 if (!isa<ShiftInst>(Op))
866 Together = ConstantExpr::get(Instruction::And, AndRHS, OpRHS);
Chris Lattnerc1e7cc02004-01-12 19:35:11 +0000867
Chris Lattnerba1cb382003-09-19 17:17:26 +0000868 switch (Op->getOpcode()) {
869 case Instruction::Xor:
Chris Lattnerc1e7cc02004-01-12 19:35:11 +0000870 if (Together->isNullValue()) {
Chris Lattnerba1cb382003-09-19 17:17:26 +0000871 // (X ^ C1) & C2 --> (X & C2) iff (C1&C2) == 0
872 return BinaryOperator::create(Instruction::And, X, AndRHS);
Chris Lattnerf95d9b92003-10-15 16:48:29 +0000873 } else if (Op->hasOneUse()) {
Chris Lattnerba1cb382003-09-19 17:17:26 +0000874 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
875 std::string OpName = Op->getName(); Op->setName("");
876 Instruction *And = BinaryOperator::create(Instruction::And,
877 X, AndRHS, OpName);
878 InsertNewInstBefore(And, TheAnd);
Chris Lattnerc1e7cc02004-01-12 19:35:11 +0000879 return BinaryOperator::create(Instruction::Xor, And, Together);
Chris Lattnerba1cb382003-09-19 17:17:26 +0000880 }
881 break;
882 case Instruction::Or:
883 // (X | C1) & C2 --> X & C2 iff C1 & C1 == 0
Chris Lattnerc1e7cc02004-01-12 19:35:11 +0000884 if (Together->isNullValue())
Chris Lattnerba1cb382003-09-19 17:17:26 +0000885 return BinaryOperator::create(Instruction::And, X, AndRHS);
886 else {
Chris Lattnerba1cb382003-09-19 17:17:26 +0000887 if (Together == AndRHS) // (X | C) & C --> C
888 return ReplaceInstUsesWith(TheAnd, AndRHS);
889
Chris Lattnerf95d9b92003-10-15 16:48:29 +0000890 if (Op->hasOneUse() && Together != OpRHS) {
Chris Lattnerba1cb382003-09-19 17:17:26 +0000891 // (X | C1) & C2 --> (X | (C1&C2)) & C2
892 std::string Op0Name = Op->getName(); Op->setName("");
893 Instruction *Or = BinaryOperator::create(Instruction::Or, X,
894 Together, Op0Name);
895 InsertNewInstBefore(Or, TheAnd);
896 return BinaryOperator::create(Instruction::And, Or, AndRHS);
897 }
898 }
899 break;
900 case Instruction::Add:
Chris Lattnerf95d9b92003-10-15 16:48:29 +0000901 if (Op->hasOneUse()) {
Chris Lattnerba1cb382003-09-19 17:17:26 +0000902 // Adding a one to a single bit bit-field should be turned into an XOR
903 // of the bit. First thing to check is to see if this AND is with a
904 // single bit constant.
905 unsigned long long AndRHSV = cast<ConstantInt>(AndRHS)->getRawValue();
906
907 // Clear bits that are not part of the constant.
908 AndRHSV &= (1ULL << AndRHS->getType()->getPrimitiveSize()*8)-1;
909
910 // If there is only one bit set...
911 if ((AndRHSV & (AndRHSV-1)) == 0) {
912 // Ok, at this point, we know that we are masking the result of the
913 // ADD down to exactly one bit. If the constant we are adding has
914 // no bits set below this bit, then we can eliminate the ADD.
915 unsigned long long AddRHS = cast<ConstantInt>(OpRHS)->getRawValue();
916
917 // Check to see if any bits below the one bit set in AndRHSV are set.
918 if ((AddRHS & (AndRHSV-1)) == 0) {
919 // If not, the only thing that can effect the output of the AND is
920 // the bit specified by AndRHSV. If that bit is set, the effect of
921 // the XOR is to toggle the bit. If it is clear, then the ADD has
922 // no effect.
923 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
924 TheAnd.setOperand(0, X);
925 return &TheAnd;
926 } else {
927 std::string Name = Op->getName(); Op->setName("");
928 // Pull the XOR out of the AND.
929 Instruction *NewAnd =
930 BinaryOperator::create(Instruction::And, X, AndRHS, Name);
931 InsertNewInstBefore(NewAnd, TheAnd);
932 return BinaryOperator::create(Instruction::Xor, NewAnd, AndRHS);
933 }
934 }
935 }
936 }
937 break;
Chris Lattner2da29172003-09-19 19:05:02 +0000938
939 case Instruction::Shl: {
940 // We know that the AND will not produce any of the bits shifted in, so if
941 // the anded constant includes them, clear them now!
942 //
943 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
Chris Lattnerc1e7cc02004-01-12 19:35:11 +0000944 Constant *CI = ConstantExpr::get(Instruction::And, AndRHS,
945 ConstantExpr::get(Instruction::Shl, AllOne, OpRHS));
Chris Lattner2da29172003-09-19 19:05:02 +0000946 if (CI != AndRHS) {
947 TheAnd.setOperand(1, CI);
948 return &TheAnd;
949 }
950 break;
951 }
952 case Instruction::Shr:
953 // We know that the AND will not produce any of the bits shifted in, so if
954 // the anded constant includes them, clear them now! This only applies to
955 // unsigned shifts, because a signed shr may bring in set bits!
956 //
957 if (AndRHS->getType()->isUnsigned()) {
958 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
Chris Lattnerc1e7cc02004-01-12 19:35:11 +0000959 Constant *CI = ConstantExpr::get(Instruction::And, AndRHS,
960 ConstantExpr::get(Instruction::Shr, AllOne, OpRHS));
Chris Lattner2da29172003-09-19 19:05:02 +0000961 if (CI != AndRHS) {
962 TheAnd.setOperand(1, CI);
963 return &TheAnd;
964 }
965 }
966 break;
Chris Lattnerba1cb382003-09-19 17:17:26 +0000967 }
968 return 0;
969}
970
Chris Lattner6d14f2a2002-08-09 23:47:40 +0000971
Chris Lattner113f4f42002-06-25 16:13:24 +0000972Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
Chris Lattnerdcf240a2003-03-10 21:43:22 +0000973 bool Changed = SimplifyCommutative(I);
Chris Lattner113f4f42002-06-25 16:13:24 +0000974 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
Chris Lattnerf4cdbf32002-05-06 16:14:14 +0000975
976 // and X, X = X and X, 0 == 0
Chris Lattnere6794492002-08-12 21:17:25 +0000977 if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
978 return ReplaceInstUsesWith(I, Op1);
Chris Lattnerf4cdbf32002-05-06 16:14:14 +0000979
980 // and X, -1 == X
Chris Lattner49b47ae2003-07-23 17:57:01 +0000981 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
Chris Lattnere6794492002-08-12 21:17:25 +0000982 if (RHS->isAllOnesValue())
983 return ReplaceInstUsesWith(I, Op0);
Chris Lattnerf4cdbf32002-05-06 16:14:14 +0000984
Chris Lattnerba1cb382003-09-19 17:17:26 +0000985 // Optimize a variety of ((val OP C1) & C2) combinations...
986 if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(Op0)) {
987 Instruction *Op0I = cast<Instruction>(Op0);
Chris Lattner33217db2003-07-23 19:36:21 +0000988 Value *X = Op0I->getOperand(0);
Chris Lattner16464b32003-07-23 19:25:52 +0000989 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
Chris Lattnerba1cb382003-09-19 17:17:26 +0000990 if (Instruction *Res = OptAndOp(Op0I, Op0CI, RHS, I))
991 return Res;
Chris Lattner33217db2003-07-23 19:36:21 +0000992 }
Chris Lattner49b47ae2003-07-23 17:57:01 +0000993 }
994
Chris Lattnerbb74e222003-03-10 23:06:50 +0000995 Value *Op0NotVal = dyn_castNotVal(Op0);
996 Value *Op1NotVal = dyn_castNotVal(Op1);
Chris Lattner3082c5a2003-02-18 19:28:33 +0000997
998 // (~A & ~B) == (~(A | B)) - Demorgan's Law
Chris Lattnerbb74e222003-03-10 23:06:50 +0000999 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
Chris Lattner3082c5a2003-02-18 19:28:33 +00001000 Instruction *Or = BinaryOperator::create(Instruction::Or, Op0NotVal,
Chris Lattner49b47ae2003-07-23 17:57:01 +00001001 Op1NotVal,I.getName()+".demorgan");
1002 InsertNewInstBefore(Or, I);
Chris Lattner3082c5a2003-02-18 19:28:33 +00001003 return BinaryOperator::createNot(Or);
1004 }
1005
1006 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
1007 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
Chris Lattner65217ff2002-08-23 18:32:43 +00001008
Chris Lattner3ac7c262003-08-13 20:16:26 +00001009 // (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1010 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
1011 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1012 return R;
1013
Chris Lattner113f4f42002-06-25 16:13:24 +00001014 return Changed ? &I : 0;
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00001015}
1016
1017
1018
Chris Lattner113f4f42002-06-25 16:13:24 +00001019Instruction *InstCombiner::visitOr(BinaryOperator &I) {
Chris Lattnerdcf240a2003-03-10 21:43:22 +00001020 bool Changed = SimplifyCommutative(I);
Chris Lattner113f4f42002-06-25 16:13:24 +00001021 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00001022
1023 // or X, X = X or X, 0 == X
Chris Lattnere6794492002-08-12 21:17:25 +00001024 if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
1025 return ReplaceInstUsesWith(I, Op0);
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00001026
1027 // or X, -1 == -1
Chris Lattner8f0d1562003-07-23 18:29:44 +00001028 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
Chris Lattnere6794492002-08-12 21:17:25 +00001029 if (RHS->isAllOnesValue())
1030 return ReplaceInstUsesWith(I, Op1);
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00001031
Chris Lattner8f0d1562003-07-23 18:29:44 +00001032 if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) {
1033 // (X & C1) | C2 --> (X | C2) & (C1|C2)
1034 if (Op0I->getOpcode() == Instruction::And && isOnlyUse(Op0))
1035 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
1036 std::string Op0Name = Op0I->getName(); Op0I->setName("");
1037 Instruction *Or = BinaryOperator::create(Instruction::Or,
1038 Op0I->getOperand(0), RHS,
1039 Op0Name);
1040 InsertNewInstBefore(Or, I);
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00001041 return BinaryOperator::create(Instruction::And, Or,
1042 ConstantExpr::get(Instruction::Or, RHS, Op0CI));
Chris Lattner8f0d1562003-07-23 18:29:44 +00001043 }
1044
1045 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
1046 if (Op0I->getOpcode() == Instruction::Xor && isOnlyUse(Op0))
1047 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
1048 std::string Op0Name = Op0I->getName(); Op0I->setName("");
1049 Instruction *Or = BinaryOperator::create(Instruction::Or,
1050 Op0I->getOperand(0), RHS,
1051 Op0Name);
1052 InsertNewInstBefore(Or, I);
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00001053 return BinaryOperator::create(Instruction::Xor, Or,
1054 ConstantExpr::get(Instruction::And, Op0CI,
1055 NotConstant(RHS)));
Chris Lattner8f0d1562003-07-23 18:29:44 +00001056 }
1057 }
1058 }
1059
Chris Lattner812aab72003-08-12 19:11:07 +00001060 // (A & C1)|(A & C2) == A & (C1|C2)
Chris Lattner01d56392003-08-12 19:17:27 +00001061 if (Instruction *LHS = dyn_cast<BinaryOperator>(Op0))
1062 if (Instruction *RHS = dyn_cast<BinaryOperator>(Op1))
1063 if (LHS->getOperand(0) == RHS->getOperand(0))
1064 if (Constant *C0 = dyn_castMaskingAnd(LHS))
1065 if (Constant *C1 = dyn_castMaskingAnd(RHS))
1066 return BinaryOperator::create(Instruction::And, LHS->getOperand(0),
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00001067 ConstantExpr::get(Instruction::Or, C0, C1));
Chris Lattner812aab72003-08-12 19:11:07 +00001068
Chris Lattner3e327a42003-03-10 23:13:59 +00001069 Value *Op0NotVal = dyn_castNotVal(Op0);
1070 Value *Op1NotVal = dyn_castNotVal(Op1);
Chris Lattner3082c5a2003-02-18 19:28:33 +00001071
Chris Lattner3e327a42003-03-10 23:13:59 +00001072 if (Op1 == Op0NotVal) // ~A | A == -1
1073 return ReplaceInstUsesWith(I,
1074 ConstantIntegral::getAllOnesValue(I.getType()));
1075
1076 if (Op0 == Op1NotVal) // A | ~A == -1
1077 return ReplaceInstUsesWith(I,
1078 ConstantIntegral::getAllOnesValue(I.getType()));
1079
1080 // (~A | ~B) == (~(A & B)) - Demorgan's Law
1081 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1082 Instruction *And = BinaryOperator::create(Instruction::And, Op0NotVal,
1083 Op1NotVal,I.getName()+".demorgan",
1084 &I);
1085 WorkList.push_back(And);
1086 return BinaryOperator::createNot(And);
1087 }
Chris Lattner3082c5a2003-02-18 19:28:33 +00001088
Chris Lattner3ac7c262003-08-13 20:16:26 +00001089 // (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B)
1090 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
1091 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1092 return R;
1093
Chris Lattner113f4f42002-06-25 16:13:24 +00001094 return Changed ? &I : 0;
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00001095}
1096
Chris Lattnerc2076352004-02-16 01:20:27 +00001097// XorSelf - Implements: X ^ X --> 0
1098struct XorSelf {
1099 Value *RHS;
1100 XorSelf(Value *rhs) : RHS(rhs) {}
1101 bool shouldApply(Value *LHS) const { return LHS == RHS; }
1102 Instruction *apply(BinaryOperator &Xor) const {
1103 return &Xor;
1104 }
1105};
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00001106
1107
Chris Lattner113f4f42002-06-25 16:13:24 +00001108Instruction *InstCombiner::visitXor(BinaryOperator &I) {
Chris Lattnerdcf240a2003-03-10 21:43:22 +00001109 bool Changed = SimplifyCommutative(I);
Chris Lattner113f4f42002-06-25 16:13:24 +00001110 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00001111
Chris Lattnerc2076352004-02-16 01:20:27 +00001112 // xor X, X = 0, even if X is nested in a sequence of Xor's.
1113 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
1114 assert(Result == &I && "AssociativeOpt didn't work?");
Chris Lattnere6794492002-08-12 21:17:25 +00001115 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
Chris Lattnerc2076352004-02-16 01:20:27 +00001116 }
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00001117
Chris Lattner97638592003-07-23 21:37:07 +00001118 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001119 // xor X, 0 == X
Chris Lattner97638592003-07-23 21:37:07 +00001120 if (RHS->isNullValue())
Chris Lattnere6794492002-08-12 21:17:25 +00001121 return ReplaceInstUsesWith(I, Op0);
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001122
Chris Lattner97638592003-07-23 21:37:07 +00001123 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
Chris Lattnerb8d6e402002-08-20 18:24:26 +00001124 // xor (setcc A, B), true = not (setcc A, B) = setncc A, B
Chris Lattner97638592003-07-23 21:37:07 +00001125 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I))
Chris Lattnerf95d9b92003-10-15 16:48:29 +00001126 if (RHS == ConstantBool::True && SCI->hasOneUse())
Chris Lattnerb8d6e402002-08-20 18:24:26 +00001127 return new SetCondInst(SCI->getInverseCondition(),
1128 SCI->getOperand(0), SCI->getOperand(1));
Chris Lattnere5806662003-11-04 23:50:51 +00001129
Chris Lattner8f2f5982003-11-05 01:06:05 +00001130 // ~(c-X) == X-c-1 == X+(-c-1)
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00001131 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
1132 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
1133 Constant *NegOp0I0C = ConstantExpr::get(Instruction::Sub,
1134 Constant::getNullValue(Op0I0C->getType()), Op0I0C);
1135 Constant *ConstantRHS = ConstantExpr::get(Instruction::Sub, NegOp0I0C,
1136 ConstantInt::get(I.getType(), 1));
1137 return BinaryOperator::create(Instruction::Add, Op0I->getOperand(1),
1138 ConstantRHS);
1139 }
Chris Lattner97638592003-07-23 21:37:07 +00001140
1141 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
Chris Lattnere5806662003-11-04 23:50:51 +00001142 switch (Op0I->getOpcode()) {
1143 case Instruction::Add:
Chris Lattner0f68fa62003-11-04 23:37:10 +00001144 // ~(X-c) --> (-c-1)-X
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00001145 if (RHS->isAllOnesValue()) {
1146 Constant *NegOp0CI = ConstantExpr::get(Instruction::Sub,
1147 Constant::getNullValue(Op0CI->getType()), Op0CI);
Chris Lattner0f68fa62003-11-04 23:37:10 +00001148 return BinaryOperator::create(Instruction::Sub,
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00001149 ConstantExpr::get(Instruction::Sub, NegOp0CI,
1150 ConstantInt::get(I.getType(), 1)),
Chris Lattner0f68fa62003-11-04 23:37:10 +00001151 Op0I->getOperand(0));
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00001152 }
Chris Lattnere5806662003-11-04 23:50:51 +00001153 break;
1154 case Instruction::And:
Chris Lattner97638592003-07-23 21:37:07 +00001155 // (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00001156 if (ConstantExpr::get(Instruction::And, RHS, Op0CI)->isNullValue())
Chris Lattner97638592003-07-23 21:37:07 +00001157 return BinaryOperator::create(Instruction::Or, Op0, RHS);
Chris Lattnere5806662003-11-04 23:50:51 +00001158 break;
1159 case Instruction::Or:
Chris Lattner97638592003-07-23 21:37:07 +00001160 // (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00001161 if (ConstantExpr::get(Instruction::And, RHS, Op0CI) == RHS)
1162 return BinaryOperator::create(Instruction::And, Op0,
1163 NotConstant(RHS));
Chris Lattnere5806662003-11-04 23:50:51 +00001164 break;
1165 default: break;
Chris Lattner97638592003-07-23 21:37:07 +00001166 }
Chris Lattnerb8d6e402002-08-20 18:24:26 +00001167 }
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00001168 }
1169
Chris Lattnerbb74e222003-03-10 23:06:50 +00001170 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
Chris Lattner3082c5a2003-02-18 19:28:33 +00001171 if (X == Op1)
1172 return ReplaceInstUsesWith(I,
1173 ConstantIntegral::getAllOnesValue(I.getType()));
1174
Chris Lattnerbb74e222003-03-10 23:06:50 +00001175 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
Chris Lattner3082c5a2003-02-18 19:28:33 +00001176 if (X == Op0)
1177 return ReplaceInstUsesWith(I,
1178 ConstantIntegral::getAllOnesValue(I.getType()));
1179
Chris Lattner1bbb7b62003-03-10 18:24:17 +00001180 if (Instruction *Op1I = dyn_cast<Instruction>(Op1))
Chris Lattnerb36d9082004-02-16 03:54:20 +00001181 if (Op1I->getOpcode() == Instruction::Or) {
Chris Lattner1bbb7b62003-03-10 18:24:17 +00001182 if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B
1183 cast<BinaryOperator>(Op1I)->swapOperands();
1184 I.swapOperands();
1185 std::swap(Op0, Op1);
1186 } else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B
1187 I.swapOperands();
1188 std::swap(Op0, Op1);
Chris Lattnerb36d9082004-02-16 03:54:20 +00001189 }
1190 } else if (Op1I->getOpcode() == Instruction::Xor) {
1191 if (Op0 == Op1I->getOperand(0)) // A^(A^B) == B
1192 return ReplaceInstUsesWith(I, Op1I->getOperand(1));
1193 else if (Op0 == Op1I->getOperand(1)) // A^(B^A) == B
1194 return ReplaceInstUsesWith(I, Op1I->getOperand(0));
1195 }
Chris Lattner1bbb7b62003-03-10 18:24:17 +00001196
1197 if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
Chris Lattnerf95d9b92003-10-15 16:48:29 +00001198 if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) {
Chris Lattner1bbb7b62003-03-10 18:24:17 +00001199 if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B
1200 cast<BinaryOperator>(Op0I)->swapOperands();
Chris Lattnerdcf240a2003-03-10 21:43:22 +00001201 if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B
Chris Lattner1bbb7b62003-03-10 18:24:17 +00001202 Value *NotB = BinaryOperator::createNot(Op1, Op1->getName()+".not", &I);
1203 WorkList.push_back(cast<Instruction>(NotB));
Chris Lattnerdcf240a2003-03-10 21:43:22 +00001204 return BinaryOperator::create(Instruction::And, Op0I->getOperand(0),
1205 NotB);
Chris Lattner1bbb7b62003-03-10 18:24:17 +00001206 }
Chris Lattnerb36d9082004-02-16 03:54:20 +00001207 } else if (Op0I->getOpcode() == Instruction::Xor) {
1208 if (Op1 == Op0I->getOperand(0)) // (A^B)^A == B
1209 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
1210 else if (Op1 == Op0I->getOperand(1)) // (B^A)^A == B
1211 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
Chris Lattner1bbb7b62003-03-10 18:24:17 +00001212 }
1213
Chris Lattner7fb29e12003-03-11 00:12:48 +00001214 // (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1^C2 == 0
1215 if (Constant *C1 = dyn_castMaskingAnd(Op0))
1216 if (Constant *C2 = dyn_castMaskingAnd(Op1))
Chris Lattner34428442003-05-27 16:40:51 +00001217 if (ConstantExpr::get(Instruction::And, C1, C2)->isNullValue())
Chris Lattner7fb29e12003-03-11 00:12:48 +00001218 return BinaryOperator::create(Instruction::Or, Op0, Op1);
1219
Chris Lattner3ac7c262003-08-13 20:16:26 +00001220 // (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B)
1221 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
1222 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1223 return R;
1224
Chris Lattner113f4f42002-06-25 16:13:24 +00001225 return Changed ? &I : 0;
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00001226}
1227
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001228// AddOne, SubOne - Add or subtract a constant one from an integer constant...
1229static Constant *AddOne(ConstantInt *C) {
Chris Lattner34428442003-05-27 16:40:51 +00001230 Constant *Result = ConstantExpr::get(Instruction::Add, C,
1231 ConstantInt::get(C->getType(), 1));
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001232 assert(Result && "Constant folding integer addition failed!");
1233 return Result;
1234}
1235static Constant *SubOne(ConstantInt *C) {
Chris Lattner34428442003-05-27 16:40:51 +00001236 Constant *Result = ConstantExpr::get(Instruction::Sub, C,
1237 ConstantInt::get(C->getType(), 1));
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001238 assert(Result && "Constant folding integer addition failed!");
1239 return Result;
1240}
1241
Chris Lattner1fc23f32002-05-09 20:11:54 +00001242// isTrueWhenEqual - Return true if the specified setcondinst instruction is
1243// true when both operands are equal...
1244//
Chris Lattner113f4f42002-06-25 16:13:24 +00001245static bool isTrueWhenEqual(Instruction &I) {
1246 return I.getOpcode() == Instruction::SetEQ ||
1247 I.getOpcode() == Instruction::SetGE ||
1248 I.getOpcode() == Instruction::SetLE;
Chris Lattner1fc23f32002-05-09 20:11:54 +00001249}
1250
Chris Lattner113f4f42002-06-25 16:13:24 +00001251Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
Chris Lattnerdcf240a2003-03-10 21:43:22 +00001252 bool Changed = SimplifyCommutative(I);
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001253 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1254 const Type *Ty = Op0->getType();
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00001255
1256 // setcc X, X
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001257 if (Op0 == Op1)
1258 return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I)));
Chris Lattner1fc23f32002-05-09 20:11:54 +00001259
Chris Lattnerd07283a2003-08-13 05:38:46 +00001260 // setcc <global/alloca*>, 0 - Global/Stack value addresses are never null!
1261 if (isa<ConstantPointerNull>(Op1) &&
1262 (isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0)))
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001263 return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I)));
1264
Chris Lattnerd07283a2003-08-13 05:38:46 +00001265
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001266 // setcc's with boolean values can always be turned into bitwise operations
1267 if (Ty == Type::BoolTy) {
1268 // If this is <, >, or !=, we can change this into a simple xor instruction
1269 if (!isTrueWhenEqual(I))
Chris Lattner16930792003-11-03 04:25:02 +00001270 return BinaryOperator::create(Instruction::Xor, Op0, Op1);
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001271
1272 // Otherwise we need to make a temporary intermediate instruction and insert
1273 // it into the instruction stream. This is what we are after:
1274 //
1275 // seteq bool %A, %B -> ~(A^B)
1276 // setle bool %A, %B -> ~A | B
1277 // setge bool %A, %B -> A | ~B
1278 //
1279 if (I.getOpcode() == Instruction::SetEQ) { // seteq case
1280 Instruction *Xor = BinaryOperator::create(Instruction::Xor, Op0, Op1,
1281 I.getName()+"tmp");
1282 InsertNewInstBefore(Xor, I);
Chris Lattner16930792003-11-03 04:25:02 +00001283 return BinaryOperator::createNot(Xor);
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001284 }
1285
1286 // Handle the setXe cases...
1287 assert(I.getOpcode() == Instruction::SetGE ||
1288 I.getOpcode() == Instruction::SetLE);
1289
1290 if (I.getOpcode() == Instruction::SetGE)
1291 std::swap(Op0, Op1); // Change setge -> setle
1292
1293 // Now we just have the SetLE case.
Chris Lattner31ae8632002-08-14 17:51:49 +00001294 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001295 InsertNewInstBefore(Not, I);
Chris Lattner16930792003-11-03 04:25:02 +00001296 return BinaryOperator::create(Instruction::Or, Not, Op1);
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001297 }
1298
1299 // Check to see if we are doing one of many comparisons against constant
1300 // integers at the end of their ranges...
1301 //
1302 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
Chris Lattnerd492a0b2003-07-23 17:02:11 +00001303 // Simplify seteq and setne instructions...
1304 if (I.getOpcode() == Instruction::SetEQ ||
1305 I.getOpcode() == Instruction::SetNE) {
1306 bool isSetNE = I.getOpcode() == Instruction::SetNE;
1307
Chris Lattnercfbce7c2003-07-23 17:26:36 +00001308 // If the first operand is (and|or|xor) with a constant, and the second
Chris Lattnerd492a0b2003-07-23 17:02:11 +00001309 // operand is a constant, simplify a bit.
Chris Lattnerc992add2003-08-13 05:33:12 +00001310 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) {
1311 switch (BO->getOpcode()) {
1312 case Instruction::Add:
1313 if (CI->isNullValue()) {
1314 // Replace ((add A, B) != 0) with (A != -B) if A or B is
1315 // efficiently invertible, or if the add has just this one use.
1316 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
1317 if (Value *NegVal = dyn_castNegVal(BOp1))
1318 return new SetCondInst(I.getOpcode(), BOp0, NegVal);
1319 else if (Value *NegVal = dyn_castNegVal(BOp0))
1320 return new SetCondInst(I.getOpcode(), NegVal, BOp1);
Chris Lattnerf95d9b92003-10-15 16:48:29 +00001321 else if (BO->hasOneUse()) {
Chris Lattnerc992add2003-08-13 05:33:12 +00001322 Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName());
1323 BO->setName("");
1324 InsertNewInstBefore(Neg, I);
1325 return new SetCondInst(I.getOpcode(), BOp0, Neg);
1326 }
1327 }
1328 break;
1329 case Instruction::Xor:
1330 // For the xor case, we can xor two constants together, eliminating
1331 // the explicit xor.
1332 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
1333 return BinaryOperator::create(I.getOpcode(), BO->getOperand(0),
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00001334 ConstantExpr::get(Instruction::Xor, CI, BOC));
Chris Lattnerc992add2003-08-13 05:33:12 +00001335
1336 // FALLTHROUGH
1337 case Instruction::Sub:
1338 // Replace (([sub|xor] A, B) != 0) with (A != B)
1339 if (CI->isNullValue())
1340 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
1341 BO->getOperand(1));
1342 break;
1343
1344 case Instruction::Or:
1345 // If bits are being or'd in that are not present in the constant we
1346 // are comparing against, then the comparison could never succeed!
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00001347 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
1348 Constant *NotCI = NotConstant(CI);
1349 if (!ConstantExpr::get(Instruction::And, BOC, NotCI)->isNullValue())
Chris Lattnerd492a0b2003-07-23 17:02:11 +00001350 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00001351 }
Chris Lattnerc992add2003-08-13 05:33:12 +00001352 break;
1353
1354 case Instruction::And:
1355 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
Chris Lattnerd492a0b2003-07-23 17:02:11 +00001356 // If bits are being compared against that are and'd out, then the
1357 // comparison can never succeed!
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00001358 if (!ConstantExpr::get(Instruction::And, CI,
1359 NotConstant(BOC))->isNullValue())
Chris Lattnerd492a0b2003-07-23 17:02:11 +00001360 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
Chris Lattnerc992add2003-08-13 05:33:12 +00001361
1362 // Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X
1363 // to be a signed value as appropriate.
1364 if (isSignBit(BOC)) {
1365 Value *X = BO->getOperand(0);
1366 // If 'X' is not signed, insert a cast now...
1367 if (!BOC->getType()->isSigned()) {
Chris Lattnere79e8542004-02-23 06:38:22 +00001368 const Type *DestTy = getSignedIntegralType(BOC->getType());
Chris Lattnerc992add2003-08-13 05:33:12 +00001369 CastInst *NewCI = new CastInst(X,DestTy,X->getName()+".signed");
1370 InsertNewInstBefore(NewCI, I);
1371 X = NewCI;
1372 }
1373 return new SetCondInst(isSetNE ? Instruction::SetLT :
1374 Instruction::SetGE, X,
1375 Constant::getNullValue(X->getType()));
1376 }
Chris Lattnerd492a0b2003-07-23 17:02:11 +00001377 }
Chris Lattnerc992add2003-08-13 05:33:12 +00001378 default: break;
1379 }
1380 }
Chris Lattnere967b342003-06-04 05:10:11 +00001381 }
Chris Lattner791ac1a2003-06-01 03:35:25 +00001382
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001383 // Check to see if we are comparing against the minimum or maximum value...
Chris Lattnere6794492002-08-12 21:17:25 +00001384 if (CI->isMinValue()) {
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001385 if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
1386 return ReplaceInstUsesWith(I, ConstantBool::False);
1387 if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
1388 return ReplaceInstUsesWith(I, ConstantBool::True);
1389 if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
Chris Lattner16930792003-11-03 04:25:02 +00001390 return BinaryOperator::create(Instruction::SetEQ, Op0, Op1);
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001391 if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
Chris Lattner16930792003-11-03 04:25:02 +00001392 return BinaryOperator::create(Instruction::SetNE, Op0, Op1);
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001393
Chris Lattnere6794492002-08-12 21:17:25 +00001394 } else if (CI->isMaxValue()) {
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001395 if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
1396 return ReplaceInstUsesWith(I, ConstantBool::False);
1397 if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
1398 return ReplaceInstUsesWith(I, ConstantBool::True);
1399 if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
Chris Lattner16930792003-11-03 04:25:02 +00001400 return BinaryOperator::create(Instruction::SetEQ, Op0, Op1);
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001401 if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
Chris Lattner16930792003-11-03 04:25:02 +00001402 return BinaryOperator::create(Instruction::SetNE, Op0, Op1);
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001403
1404 // Comparing against a value really close to min or max?
1405 } else if (isMinValuePlusOne(CI)) {
1406 if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
Chris Lattner16930792003-11-03 04:25:02 +00001407 return BinaryOperator::create(Instruction::SetEQ, Op0, SubOne(CI));
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001408 if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
Chris Lattner16930792003-11-03 04:25:02 +00001409 return BinaryOperator::create(Instruction::SetNE, Op0, SubOne(CI));
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001410
1411 } else if (isMaxValueMinusOne(CI)) {
1412 if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
Chris Lattner16930792003-11-03 04:25:02 +00001413 return BinaryOperator::create(Instruction::SetEQ, Op0, AddOne(CI));
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001414 if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
Chris Lattner16930792003-11-03 04:25:02 +00001415 return BinaryOperator::create(Instruction::SetNE, Op0, AddOne(CI));
Chris Lattner6d14f2a2002-08-09 23:47:40 +00001416 }
Chris Lattner59611142004-02-23 05:47:48 +00001417
1418 // If we still have a setle or setge instruction, turn it into the
1419 // appropriate setlt or setgt instruction. Since the border cases have
1420 // already been handled above, this requires little checking.
1421 //
1422 if (I.getOpcode() == Instruction::SetLE)
1423 return BinaryOperator::create(Instruction::SetLT, Op0, AddOne(CI));
1424 if (I.getOpcode() == Instruction::SetGE)
1425 return BinaryOperator::create(Instruction::SetGT, Op0, SubOne(CI));
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00001426 }
1427
Chris Lattner16930792003-11-03 04:25:02 +00001428 // Test to see if the operands of the setcc are casted versions of other
1429 // values. If the cast can be stripped off both arguments, we do so now.
Chris Lattner6444c372003-11-03 05:17:03 +00001430 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
1431 Value *CastOp0 = CI->getOperand(0);
1432 if (CastOp0->getType()->isLosslesslyConvertibleTo(CI->getType()) &&
Chris Lattner16930792003-11-03 04:25:02 +00001433 !isa<Argument>(Op1) &&
1434 (I.getOpcode() == Instruction::SetEQ ||
1435 I.getOpcode() == Instruction::SetNE)) {
1436 // We keep moving the cast from the left operand over to the right
1437 // operand, where it can often be eliminated completely.
Chris Lattner6444c372003-11-03 05:17:03 +00001438 Op0 = CastOp0;
Chris Lattner16930792003-11-03 04:25:02 +00001439
1440 // If operand #1 is a cast instruction, see if we can eliminate it as
1441 // well.
Chris Lattner6444c372003-11-03 05:17:03 +00001442 if (CastInst *CI2 = dyn_cast<CastInst>(Op1))
1443 if (CI2->getOperand(0)->getType()->isLosslesslyConvertibleTo(
Chris Lattner16930792003-11-03 04:25:02 +00001444 Op0->getType()))
Chris Lattner6444c372003-11-03 05:17:03 +00001445 Op1 = CI2->getOperand(0);
Chris Lattner16930792003-11-03 04:25:02 +00001446
1447 // If Op1 is a constant, we can fold the cast into the constant.
1448 if (Op1->getType() != Op0->getType())
1449 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
1450 Op1 = ConstantExpr::getCast(Op1C, Op0->getType());
1451 } else {
1452 // Otherwise, cast the RHS right before the setcc
1453 Op1 = new CastInst(Op1, Op0->getType(), Op1->getName());
1454 InsertNewInstBefore(cast<Instruction>(Op1), I);
1455 }
1456 return BinaryOperator::create(I.getOpcode(), Op0, Op1);
1457 }
1458
Chris Lattner6444c372003-11-03 05:17:03 +00001459 // Handle the special case of: setcc (cast bool to X), <cst>
1460 // This comes up when you have code like
1461 // int X = A < B;
1462 // if (X) ...
1463 // For generality, we handle any zero-extension of any operand comparison
1464 // with a constant.
1465 if (ConstantInt *ConstantRHS = dyn_cast<ConstantInt>(Op1)) {
1466 const Type *SrcTy = CastOp0->getType();
1467 const Type *DestTy = Op0->getType();
1468 if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
1469 (SrcTy->isUnsigned() || SrcTy == Type::BoolTy)) {
1470 // Ok, we have an expansion of operand 0 into a new type. Get the
1471 // constant value, masink off bits which are not set in the RHS. These
1472 // could be set if the destination value is signed.
1473 uint64_t ConstVal = ConstantRHS->getRawValue();
1474 ConstVal &= (1ULL << DestTy->getPrimitiveSize()*8)-1;
1475
1476 // If the constant we are comparing it with has high bits set, which
1477 // don't exist in the original value, the values could never be equal,
1478 // because the source would be zero extended.
1479 unsigned SrcBits =
1480 SrcTy == Type::BoolTy ? 1 : SrcTy->getPrimitiveSize()*8;
Chris Lattner7c94d112003-11-05 17:31:36 +00001481 bool HasSignBit = ConstVal & (1ULL << (DestTy->getPrimitiveSize()*8-1));
1482 if (ConstVal & ~((1ULL << SrcBits)-1)) {
Chris Lattner6444c372003-11-03 05:17:03 +00001483 switch (I.getOpcode()) {
1484 default: assert(0 && "Unknown comparison type!");
1485 case Instruction::SetEQ:
1486 return ReplaceInstUsesWith(I, ConstantBool::False);
1487 case Instruction::SetNE:
1488 return ReplaceInstUsesWith(I, ConstantBool::True);
1489 case Instruction::SetLT:
1490 case Instruction::SetLE:
1491 if (DestTy->isSigned() && HasSignBit)
1492 return ReplaceInstUsesWith(I, ConstantBool::False);
1493 return ReplaceInstUsesWith(I, ConstantBool::True);
1494 case Instruction::SetGT:
1495 case Instruction::SetGE:
1496 if (DestTy->isSigned() && HasSignBit)
1497 return ReplaceInstUsesWith(I, ConstantBool::True);
1498 return ReplaceInstUsesWith(I, ConstantBool::False);
1499 }
1500 }
1501
1502 // Otherwise, we can replace the setcc with a setcc of the smaller
1503 // operand value.
1504 Op1 = ConstantExpr::getCast(cast<Constant>(Op1), SrcTy);
1505 return BinaryOperator::create(I.getOpcode(), CastOp0, Op1);
1506 }
1507 }
1508 }
Chris Lattner113f4f42002-06-25 16:13:24 +00001509 return Changed ? &I : 0;
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00001510}
1511
1512
1513
Chris Lattnere8d6c602003-03-10 19:16:08 +00001514Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
Chris Lattner113f4f42002-06-25 16:13:24 +00001515 assert(I.getOperand(1)->getType() == Type::UByteTy);
1516 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
Chris Lattnerdeaa0dd2003-08-12 21:53:41 +00001517 bool isLeftShift = I.getOpcode() == Instruction::Shl;
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00001518
1519 // shl X, 0 == X and shr X, 0 == X
1520 // shl 0, X == 0 and shr 0, X == 0
1521 if (Op1 == Constant::getNullValue(Type::UByteTy) ||
Chris Lattnere6794492002-08-12 21:17:25 +00001522 Op0 == Constant::getNullValue(Op0->getType()))
1523 return ReplaceInstUsesWith(I, Op0);
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00001524
Chris Lattnerdeaa0dd2003-08-12 21:53:41 +00001525 // shr int -1, X = -1 (for any arithmetic shift rights of ~0)
1526 if (!isLeftShift)
1527 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
1528 if (CSI->isAllOnesValue())
1529 return ReplaceInstUsesWith(I, CSI);
1530
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00001531 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) {
Chris Lattner3204d4e2003-07-24 17:52:58 +00001532 // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
1533 // of a signed value.
1534 //
Chris Lattnere8d6c602003-03-10 19:16:08 +00001535 unsigned TypeBits = Op0->getType()->getPrimitiveSize()*8;
1536 if (CUI->getValue() >= TypeBits &&
Chris Lattnerdeaa0dd2003-08-12 21:53:41 +00001537 (!Op0->getType()->isSigned() || isLeftShift))
Chris Lattnere8d6c602003-03-10 19:16:08 +00001538 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
Chris Lattner55f3d942002-09-10 23:04:09 +00001539
Chris Lattnerede3fe02003-08-13 04:18:28 +00001540 // ((X*C1) << C2) == (X * (C1 << C2))
1541 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
1542 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
1543 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
1544 return BinaryOperator::create(Instruction::Mul, BO->getOperand(0),
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00001545 ConstantExpr::get(Instruction::Shl, BOOp, CUI));
Chris Lattnerede3fe02003-08-13 04:18:28 +00001546
1547
Chris Lattnerdeaa0dd2003-08-12 21:53:41 +00001548 // If the operand is an bitwise operator with a constant RHS, and the
1549 // shift is the only use, we can pull it out of the shift.
Chris Lattnerf95d9b92003-10-15 16:48:29 +00001550 if (Op0->hasOneUse())
Chris Lattnerdeaa0dd2003-08-12 21:53:41 +00001551 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0))
1552 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
1553 bool isValid = true; // Valid only for And, Or, Xor
1554 bool highBitSet = false; // Transform if high bit of constant set?
1555
1556 switch (Op0BO->getOpcode()) {
1557 default: isValid = false; break; // Do not perform transform!
1558 case Instruction::Or:
1559 case Instruction::Xor:
1560 highBitSet = false;
1561 break;
1562 case Instruction::And:
1563 highBitSet = true;
1564 break;
1565 }
1566
1567 // If this is a signed shift right, and the high bit is modified
1568 // by the logical operation, do not perform the transformation.
1569 // The highBitSet boolean indicates the value of the high bit of
1570 // the constant which would cause it to be modified for this
1571 // operation.
1572 //
1573 if (isValid && !isLeftShift && !I.getType()->isUnsigned()) {
1574 uint64_t Val = Op0C->getRawValue();
1575 isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet;
1576 }
1577
1578 if (isValid) {
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00001579 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, CUI);
Chris Lattnerdeaa0dd2003-08-12 21:53:41 +00001580
1581 Instruction *NewShift =
1582 new ShiftInst(I.getOpcode(), Op0BO->getOperand(0), CUI,
1583 Op0BO->getName());
1584 Op0BO->setName("");
1585 InsertNewInstBefore(NewShift, I);
1586
1587 return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
1588 NewRHS);
1589 }
1590 }
1591
Chris Lattner3204d4e2003-07-24 17:52:58 +00001592 // If this is a shift of a shift, see if we can fold the two together...
Chris Lattnerdeaa0dd2003-08-12 21:53:41 +00001593 if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0))
Chris Lattnerab780df2003-07-24 18:38:56 +00001594 if (ConstantUInt *ShiftAmt1C =
1595 dyn_cast<ConstantUInt>(Op0SI->getOperand(1))) {
Chris Lattner3204d4e2003-07-24 17:52:58 +00001596 unsigned ShiftAmt1 = ShiftAmt1C->getValue();
1597 unsigned ShiftAmt2 = CUI->getValue();
1598
1599 // Check for (A << c1) << c2 and (A >> c1) >> c2
1600 if (I.getOpcode() == Op0SI->getOpcode()) {
1601 unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift...
1602 return new ShiftInst(I.getOpcode(), Op0SI->getOperand(0),
1603 ConstantUInt::get(Type::UByteTy, Amt));
1604 }
1605
Chris Lattnerab780df2003-07-24 18:38:56 +00001606 // Check for (A << c1) >> c2 or visaversa. If we are dealing with
1607 // signed types, we can only support the (A >> c1) << c2 configuration,
1608 // because it can not turn an arbitrary bit of A into a sign bit.
Chris Lattnerdeaa0dd2003-08-12 21:53:41 +00001609 if (I.getType()->isUnsigned() || isLeftShift) {
Chris Lattner3204d4e2003-07-24 17:52:58 +00001610 // Calculate bitmask for what gets shifted off the edge...
1611 Constant *C = ConstantIntegral::getAllOnesValue(I.getType());
Chris Lattnerdeaa0dd2003-08-12 21:53:41 +00001612 if (isLeftShift)
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00001613 C = ConstantExpr::get(Instruction::Shl, C, ShiftAmt1C);
Chris Lattnerdeaa0dd2003-08-12 21:53:41 +00001614 else
Chris Lattnerc1e7cc02004-01-12 19:35:11 +00001615 C = ConstantExpr::get(Instruction::Shr, C, ShiftAmt1C);
Chris Lattner3204d4e2003-07-24 17:52:58 +00001616
1617 Instruction *Mask =
1618 BinaryOperator::create(Instruction::And, Op0SI->getOperand(0),
1619 C, Op0SI->getOperand(0)->getName()+".mask");
1620 InsertNewInstBefore(Mask, I);
1621
1622 // Figure out what flavor of shift we should use...
1623 if (ShiftAmt1 == ShiftAmt2)
1624 return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2
1625 else if (ShiftAmt1 < ShiftAmt2) {
1626 return new ShiftInst(I.getOpcode(), Mask,
1627 ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1));
1628 } else {
1629 return new ShiftInst(Op0SI->getOpcode(), Mask,
1630 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
1631 }
1632 }
1633 }
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00001634 }
Chris Lattner2e0fb392002-10-08 16:16:40 +00001635
Chris Lattnerf4cdbf32002-05-06 16:14:14 +00001636 return 0;
1637}
1638
1639
Chris Lattner48a44f72002-05-02 17:06:02 +00001640// isEliminableCastOfCast - Return true if it is valid to eliminate the CI
1641// instruction.
1642//
Chris Lattnerdfae8be2003-07-24 17:35:25 +00001643static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
1644 const Type *DstTy) {
Chris Lattner48a44f72002-05-02 17:06:02 +00001645
Chris Lattner650b6da2002-08-02 20:00:25 +00001646 // It is legal to eliminate the instruction if casting A->B->A if the sizes
1647 // are identical and the bits don't get reinterpreted (for example
Chris Lattner0bb75912002-08-14 23:21:10 +00001648 // int->float->int would not be allowed)
Misha Brukmane5838c42003-05-20 18:45:36 +00001649 if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy))
Chris Lattner650b6da2002-08-02 20:00:25 +00001650 return true;
Chris Lattner48a44f72002-05-02 17:06:02 +00001651
1652 // Allow free casting and conversion of sizes as long as the sign doesn't
1653 // change...
Chris Lattnerb0b412e2002-09-03 01:08:28 +00001654 if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
Chris Lattner650b6da2002-08-02 20:00:25 +00001655 unsigned SrcSize = SrcTy->getPrimitiveSize();
1656 unsigned MidSize = MidTy->getPrimitiveSize();
1657 unsigned DstSize = DstTy->getPrimitiveSize();
Chris Lattner650b6da2002-08-02 20:00:25 +00001658
Chris Lattner3732aca2002-08-15 16:15:25 +00001659 // Cases where we are monotonically decreasing the size of the type are
1660 // always ok, regardless of what sign changes are going on.
1661 //
Chris Lattner0bb75912002-08-14 23:21:10 +00001662 if (SrcSize >= MidSize && MidSize >= DstSize)
Chris Lattner650b6da2002-08-02 20:00:25 +00001663 return true;
Chris Lattner3732aca2002-08-15 16:15:25 +00001664
Chris Lattner555518c2002-09-23 23:39:43 +00001665 // Cases where the source and destination type are the same, but the middle
1666 // type is bigger are noops.
1667 //
1668 if (SrcSize == DstSize && MidSize > SrcSize)
1669 return true;
1670
Chris Lattner3732aca2002-08-15 16:15:25 +00001671 // If we are monotonically growing, things are more complex.
1672 //
1673 if (SrcSize <= MidSize && MidSize <= DstSize) {
1674 // We have eight combinations of signedness to worry about. Here's the
1675 // table:
1676 static const int SignTable[8] = {
1677 // CODE, SrcSigned, MidSigned, DstSigned, Comment
1678 1, // U U U Always ok
1679 1, // U U S Always ok
1680 3, // U S U Ok iff SrcSize != MidSize
1681 3, // U S S Ok iff SrcSize != MidSize
1682 0, // S U U Never ok
1683 2, // S U S Ok iff MidSize == DstSize
1684 1, // S S U Always ok
1685 1, // S S S Always ok
1686 };
1687
1688 // Choose an action based on the current entry of the signtable that this
1689 // cast of cast refers to...
1690 unsigned Row = SrcTy->isSigned()*4+MidTy->isSigned()*2+DstTy->isSigned();
1691 switch (SignTable[Row]) {
1692 case 0: return false; // Never ok
1693 case 1: return true; // Always ok
1694 case 2: return MidSize == DstSize; // Ok iff MidSize == DstSize
1695 case 3: // Ok iff SrcSize != MidSize
1696 return SrcSize != MidSize || SrcTy == Type::BoolTy;
1697 default: assert(0 && "Bad entry in sign table!");
1698 }
Chris Lattner3732aca2002-08-15 16:15:25 +00001699 }
Chris Lattner650b6da2002-08-02 20:00:25 +00001700 }
Chris Lattner48a44f72002-05-02 17:06:02 +00001701
1702 // Otherwise, we cannot succeed. Specifically we do not want to allow things
1703 // like: short -> ushort -> uint, because this can create wrong results if
1704 // the input short is negative!
1705 //
1706 return false;
1707}
1708
Chris Lattnerdfae8be2003-07-24 17:35:25 +00001709static bool ValueRequiresCast(const Value *V, const Type *Ty) {
1710 if (V->getType() == Ty || isa<Constant>(V)) return false;
1711 if (const CastInst *CI = dyn_cast<CastInst>(V))
1712 if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty))
1713 return false;
1714 return true;
1715}
1716
1717/// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
1718/// InsertBefore instruction. This is specialized a bit to avoid inserting
1719/// casts that are known to not do anything...
1720///
1721Value *InstCombiner::InsertOperandCastBefore(Value *V, const Type *DestTy,
1722 Instruction *InsertBefore) {
1723 if (V->getType() == DestTy) return V;
1724 if (Constant *C = dyn_cast<Constant>(V))
1725 return ConstantExpr::getCast(C, DestTy);
1726
1727 CastInst *CI = new CastInst(V, DestTy, V->getName());
1728 InsertNewInstBefore(CI, *InsertBefore);
1729 return CI;
1730}
Chris Lattner48a44f72002-05-02 17:06:02 +00001731
1732// CastInst simplification
Chris Lattner260ab202002-04-18 17:39:14 +00001733//
Chris Lattner113f4f42002-06-25 16:13:24 +00001734Instruction *InstCombiner::visitCastInst(CastInst &CI) {
Chris Lattner55d4bda2003-06-23 21:59:52 +00001735 Value *Src = CI.getOperand(0);
1736
Chris Lattner48a44f72002-05-02 17:06:02 +00001737 // If the user is casting a value to the same type, eliminate this cast
1738 // instruction...
Chris Lattner55d4bda2003-06-23 21:59:52 +00001739 if (CI.getType() == Src->getType())
1740 return ReplaceInstUsesWith(CI, Src);
Chris Lattner48a44f72002-05-02 17:06:02 +00001741
Chris Lattner48a44f72002-05-02 17:06:02 +00001742 // If casting the result of another cast instruction, try to eliminate this
1743 // one!
1744 //
Chris Lattner55d4bda2003-06-23 21:59:52 +00001745 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) {
Chris Lattnerdfae8be2003-07-24 17:35:25 +00001746 if (isEliminableCastOfCast(CSrc->getOperand(0)->getType(),
1747 CSrc->getType(), CI.getType())) {
Chris Lattner48a44f72002-05-02 17:06:02 +00001748 // This instruction now refers directly to the cast's src operand. This
1749 // has a good chance of making CSrc dead.
Chris Lattner113f4f42002-06-25 16:13:24 +00001750 CI.setOperand(0, CSrc->getOperand(0));
1751 return &CI;
Chris Lattner48a44f72002-05-02 17:06:02 +00001752 }
1753
Chris Lattner650b6da2002-08-02 20:00:25 +00001754 // If this is an A->B->A cast, and we are dealing with integral types, try
1755 // to convert this into a logical 'and' instruction.
1756 //
1757 if (CSrc->getOperand(0)->getType() == CI.getType() &&
Chris Lattnerb0b412e2002-09-03 01:08:28 +00001758 CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
Chris Lattner650b6da2002-08-02 20:00:25 +00001759 CI.getType()->isUnsigned() && CSrc->getType()->isUnsigned() &&
1760 CSrc->getType()->getPrimitiveSize() < CI.getType()->getPrimitiveSize()){
1761 assert(CSrc->getType() != Type::ULongTy &&
1762 "Cannot have type bigger than ulong!");
Chris Lattner196897c2003-05-26 23:41:32 +00001763 uint64_t AndValue = (1ULL << CSrc->getType()->getPrimitiveSize()*8)-1;
Chris Lattner650b6da2002-08-02 20:00:25 +00001764 Constant *AndOp = ConstantUInt::get(CI.getType(), AndValue);
1765 return BinaryOperator::create(Instruction::And, CSrc->getOperand(0),
1766 AndOp);
1767 }
1768 }
1769
Chris Lattnerd0d51602003-06-21 23:12:02 +00001770 // If casting the result of a getelementptr instruction with no offset, turn
1771 // this into a cast of the original pointer!
1772 //
Chris Lattner55d4bda2003-06-23 21:59:52 +00001773 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
Chris Lattnerd0d51602003-06-21 23:12:02 +00001774 bool AllZeroOperands = true;
1775 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
1776 if (!isa<Constant>(GEP->getOperand(i)) ||
1777 !cast<Constant>(GEP->getOperand(i))->isNullValue()) {
1778 AllZeroOperands = false;
1779 break;
1780 }
1781 if (AllZeroOperands) {
1782 CI.setOperand(0, GEP->getOperand(0));
1783 return &CI;
1784 }
1785 }
1786
Chris Lattnerf4ad1652003-11-02 05:57:39 +00001787 // If we are casting a malloc or alloca to a pointer to a type of the same
1788 // size, rewrite the allocation instruction to allocate the "right" type.
1789 //
1790 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
Chris Lattnerd4d987d2003-11-02 06:54:48 +00001791 if (AI->hasOneUse() && !AI->isArrayAllocation())
Chris Lattnerf4ad1652003-11-02 05:57:39 +00001792 if (const PointerType *PTy = dyn_cast<PointerType>(CI.getType())) {
1793 // Get the type really allocated and the type casted to...
1794 const Type *AllocElTy = AI->getAllocatedType();
1795 unsigned AllocElTySize = TD->getTypeSize(AllocElTy);
1796 const Type *CastElTy = PTy->getElementType();
1797 unsigned CastElTySize = TD->getTypeSize(CastElTy);
Chris Lattner7c94d112003-11-05 17:31:36 +00001798
Chris Lattnerf4ad1652003-11-02 05:57:39 +00001799 // If the allocation is for an even multiple of the cast type size
Chris Lattneraf789322003-11-03 01:29:41 +00001800 if (CastElTySize && (AllocElTySize % CastElTySize == 0)) {
Chris Lattnerf4ad1652003-11-02 05:57:39 +00001801 Value *Amt = ConstantUInt::get(Type::UIntTy,
1802 AllocElTySize/CastElTySize);
1803 std::string Name = AI->getName(); AI->setName("");
1804 AllocationInst *New;
1805 if (isa<MallocInst>(AI))
1806 New = new MallocInst(CastElTy, Amt, Name);
1807 else
1808 New = new AllocaInst(CastElTy, Amt, Name);
1809 InsertNewInstBefore(New, CI);
1810 return ReplaceInstUsesWith(CI, New);
1811 }
1812 }
1813
Chris Lattnerdfae8be2003-07-24 17:35:25 +00001814 // If the source value is an instruction with only this use, we can attempt to
1815 // propagate the cast into the instruction. Also, only handle integral types
1816 // for now.
1817 if (Instruction *SrcI = dyn_cast<Instruction>(Src))
Chris Lattnerf95d9b92003-10-15 16:48:29 +00001818 if (SrcI->hasOneUse() && Src->getType()->isIntegral() &&
Chris Lattnerdfae8be2003-07-24 17:35:25 +00001819 CI.getType()->isInteger()) { // Don't mess with casts to bool here
1820 const Type *DestTy = CI.getType();
1821 unsigned SrcBitSize = getTypeSizeInBits(Src->getType());
1822 unsigned DestBitSize = getTypeSizeInBits(DestTy);
1823
1824 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
1825 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
1826
1827 switch (SrcI->getOpcode()) {
1828 case Instruction::Add:
1829 case Instruction::Mul:
1830 case Instruction::And:
1831 case Instruction::Or:
1832 case Instruction::Xor:
1833 // If we are discarding information, or just changing the sign, rewrite.
1834 if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
1835 // Don't insert two casts if they cannot be eliminated. We allow two
1836 // casts to be inserted if the sizes are the same. This could only be
1837 // converting signedness, which is a noop.
1838 if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy) ||
1839 !ValueRequiresCast(Op0, DestTy)) {
1840 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
1841 Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI);
1842 return BinaryOperator::create(cast<BinaryOperator>(SrcI)
1843 ->getOpcode(), Op0c, Op1c);
1844 }
1845 }
1846 break;
1847 case Instruction::Shl:
1848 // Allow changing the sign of the source operand. Do not allow changing
1849 // the size of the shift, UNLESS the shift amount is a constant. We
1850 // mush not change variable sized shifts to a smaller size, because it
1851 // is undefined to shift more bits out than exist in the value.
1852 if (DestBitSize == SrcBitSize ||
1853 (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
1854 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
1855 return new ShiftInst(Instruction::Shl, Op0c, Op1);
1856 }
1857 break;
1858 }
1859 }
1860
Chris Lattner260ab202002-04-18 17:39:14 +00001861 return 0;
Chris Lattnerca081252001-12-14 16:52:21 +00001862}
1863
Chris Lattner970c33a2003-06-19 17:00:31 +00001864// CallInst simplification
1865//
1866Instruction *InstCombiner::visitCallInst(CallInst &CI) {
Chris Lattneraec3d942003-10-07 22:32:43 +00001867 return visitCallSite(&CI);
Chris Lattner970c33a2003-06-19 17:00:31 +00001868}
1869
1870// InvokeInst simplification
1871//
1872Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
Chris Lattneraec3d942003-10-07 22:32:43 +00001873 return visitCallSite(&II);
Chris Lattner970c33a2003-06-19 17:00:31 +00001874}
1875
Chris Lattneraec3d942003-10-07 22:32:43 +00001876// visitCallSite - Improvements for call and invoke instructions.
1877//
1878Instruction *InstCombiner::visitCallSite(CallSite CS) {
Chris Lattner75b4d1d2003-10-07 22:54:13 +00001879 bool Changed = false;
1880
1881 // If the callee is a constexpr cast of a function, attempt to move the cast
1882 // to the arguments of the call/invoke.
Chris Lattneraec3d942003-10-07 22:32:43 +00001883 if (transformConstExprCastCall(CS)) return 0;
1884
Chris Lattner75b4d1d2003-10-07 22:54:13 +00001885 Value *Callee = CS.getCalledValue();
1886 const PointerType *PTy = cast<PointerType>(Callee->getType());
1887 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1888 if (FTy->isVarArg()) {
1889 // See if we can optimize any arguments passed through the varargs area of
1890 // the call.
1891 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
1892 E = CS.arg_end(); I != E; ++I)
1893 if (CastInst *CI = dyn_cast<CastInst>(*I)) {
1894 // If this cast does not effect the value passed through the varargs
1895 // area, we can eliminate the use of the cast.
1896 Value *Op = CI->getOperand(0);
1897 if (CI->getType()->isLosslesslyConvertibleTo(Op->getType())) {
1898 *I = Op;
1899 Changed = true;
1900 }
1901 }
1902 }
Chris Lattneraec3d942003-10-07 22:32:43 +00001903
Chris Lattner75b4d1d2003-10-07 22:54:13 +00001904 return Changed ? CS.getInstruction() : 0;
Chris Lattneraec3d942003-10-07 22:32:43 +00001905}
1906
Chris Lattner970c33a2003-06-19 17:00:31 +00001907// transformConstExprCastCall - If the callee is a constexpr cast of a function,
1908// attempt to move the cast to the arguments of the call/invoke.
1909//
1910bool InstCombiner::transformConstExprCastCall(CallSite CS) {
1911 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
1912 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
1913 if (CE->getOpcode() != Instruction::Cast ||
1914 !isa<ConstantPointerRef>(CE->getOperand(0)))
1915 return false;
1916 ConstantPointerRef *CPR = cast<ConstantPointerRef>(CE->getOperand(0));
1917 if (!isa<Function>(CPR->getValue())) return false;
1918 Function *Callee = cast<Function>(CPR->getValue());
1919 Instruction *Caller = CS.getInstruction();
1920
1921 // Okay, this is a cast from a function to a different type. Unless doing so
1922 // would cause a type conversion of one of our arguments, change this call to
1923 // be a direct call with arguments casted to the appropriate types.
1924 //
1925 const FunctionType *FT = Callee->getFunctionType();
1926 const Type *OldRetTy = Caller->getType();
1927
Chris Lattner1f7942f2004-01-14 06:06:08 +00001928 // Check to see if we are changing the return type...
1929 if (OldRetTy != FT->getReturnType()) {
1930 if (Callee->isExternal() &&
1931 !OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) &&
1932 !Caller->use_empty())
1933 return false; // Cannot transform this return value...
1934
1935 // If the callsite is an invoke instruction, and the return value is used by
1936 // a PHI node in a successor, we cannot change the return type of the call
1937 // because there is no place to put the cast instruction (without breaking
1938 // the critical edge). Bail out in this case.
1939 if (!Caller->use_empty())
1940 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
1941 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
1942 UI != E; ++UI)
1943 if (PHINode *PN = dyn_cast<PHINode>(*UI))
1944 if (PN->getParent() == II->getNormalDest() ||
Chris Lattnerfae8ab32004-02-08 21:44:31 +00001945 PN->getParent() == II->getUnwindDest())
Chris Lattner1f7942f2004-01-14 06:06:08 +00001946 return false;
1947 }
Chris Lattner970c33a2003-06-19 17:00:31 +00001948
1949 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
1950 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
1951
1952 CallSite::arg_iterator AI = CS.arg_begin();
1953 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
1954 const Type *ParamTy = FT->getParamType(i);
1955 bool isConvertible = (*AI)->getType()->isLosslesslyConvertibleTo(ParamTy);
1956 if (Callee->isExternal() && !isConvertible) return false;
1957 }
1958
1959 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
1960 Callee->isExternal())
1961 return false; // Do not delete arguments unless we have a function body...
1962
1963 // Okay, we decided that this is a safe thing to do: go ahead and start
1964 // inserting cast instructions as necessary...
1965 std::vector<Value*> Args;
1966 Args.reserve(NumActualArgs);
1967
1968 AI = CS.arg_begin();
1969 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
1970 const Type *ParamTy = FT->getParamType(i);
1971 if ((*AI)->getType() == ParamTy) {
1972 Args.push_back(*AI);
1973 } else {
1974 Instruction *Cast = new CastInst(*AI, ParamTy, "tmp");
1975 InsertNewInstBefore(Cast, *Caller);
1976 Args.push_back(Cast);
1977 }
1978 }
1979
1980 // If the function takes more arguments than the call was taking, add them
1981 // now...
1982 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
1983 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
1984
1985 // If we are removing arguments to the function, emit an obnoxious warning...
1986 if (FT->getNumParams() < NumActualArgs)
1987 if (!FT->isVarArg()) {
1988 std::cerr << "WARNING: While resolving call to function '"
1989 << Callee->getName() << "' arguments were dropped!\n";
1990 } else {
1991 // Add all of the arguments in their promoted form to the arg list...
1992 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
1993 const Type *PTy = getPromotedType((*AI)->getType());
1994 if (PTy != (*AI)->getType()) {
1995 // Must promote to pass through va_arg area!
1996 Instruction *Cast = new CastInst(*AI, PTy, "tmp");
1997 InsertNewInstBefore(Cast, *Caller);
1998 Args.push_back(Cast);
1999 } else {
2000 Args.push_back(*AI);
2001 }
2002 }
2003 }
2004
2005 if (FT->getReturnType() == Type::VoidTy)
2006 Caller->setName(""); // Void type should not have a name...
2007
2008 Instruction *NC;
2009 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
Chris Lattnerfae8ab32004-02-08 21:44:31 +00002010 NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
Chris Lattner970c33a2003-06-19 17:00:31 +00002011 Args, Caller->getName(), Caller);
2012 } else {
2013 NC = new CallInst(Callee, Args, Caller->getName(), Caller);
2014 }
2015
2016 // Insert a cast of the return type as necessary...
2017 Value *NV = NC;
2018 if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
2019 if (NV->getType() != Type::VoidTy) {
2020 NV = NC = new CastInst(NC, Caller->getType(), "tmp");
Chris Lattner686767f2003-10-30 00:46:41 +00002021
2022 // If this is an invoke instruction, we should insert it after the first
2023 // non-phi, instruction in the normal successor block.
2024 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
2025 BasicBlock::iterator I = II->getNormalDest()->begin();
2026 while (isa<PHINode>(I)) ++I;
2027 InsertNewInstBefore(NC, *I);
2028 } else {
2029 // Otherwise, it's a call, just insert cast right after the call instr
2030 InsertNewInstBefore(NC, *Caller);
2031 }
Chris Lattner970c33a2003-06-19 17:00:31 +00002032 AddUsesToWorkList(*Caller);
2033 } else {
2034 NV = Constant::getNullValue(Caller->getType());
2035 }
2036 }
2037
2038 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
2039 Caller->replaceAllUsesWith(NV);
2040 Caller->getParent()->getInstList().erase(Caller);
2041 removeFromWorkList(Caller);
2042 return true;
2043}
2044
2045
Chris Lattner48a44f72002-05-02 17:06:02 +00002046
Chris Lattnerbbbdd852002-05-06 18:06:38 +00002047// PHINode simplification
2048//
Chris Lattner113f4f42002-06-25 16:13:24 +00002049Instruction *InstCombiner::visitPHINode(PHINode &PN) {
Chris Lattner91daeb52003-12-19 05:58:40 +00002050 if (Value *V = hasConstantValue(&PN))
2051 return ReplaceInstUsesWith(PN, V);
Chris Lattner4db2d222004-02-16 05:07:08 +00002052
2053 // If the only user of this instruction is a cast instruction, and all of the
2054 // incoming values are constants, change this PHI to merge together the casted
2055 // constants.
2056 if (PN.hasOneUse())
2057 if (CastInst *CI = dyn_cast<CastInst>(PN.use_back()))
2058 if (CI->getType() != PN.getType()) { // noop casts will be folded
2059 bool AllConstant = true;
2060 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
2061 if (!isa<Constant>(PN.getIncomingValue(i))) {
2062 AllConstant = false;
2063 break;
2064 }
2065 if (AllConstant) {
2066 // Make a new PHI with all casted values.
2067 PHINode *New = new PHINode(CI->getType(), PN.getName(), &PN);
2068 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
2069 Constant *OldArg = cast<Constant>(PN.getIncomingValue(i));
2070 New->addIncoming(ConstantExpr::getCast(OldArg, New->getType()),
2071 PN.getIncomingBlock(i));
2072 }
2073
2074 // Update the cast instruction.
2075 CI->setOperand(0, New);
2076 WorkList.push_back(CI); // revisit the cast instruction to fold.
2077 WorkList.push_back(New); // Make sure to revisit the new Phi
2078 return &PN; // PN is now dead!
2079 }
2080 }
Chris Lattner91daeb52003-12-19 05:58:40 +00002081 return 0;
Chris Lattnerbbbdd852002-05-06 18:06:38 +00002082}
2083
Chris Lattner48a44f72002-05-02 17:06:02 +00002084
Chris Lattner113f4f42002-06-25 16:13:24 +00002085Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
Chris Lattner471bd762003-05-22 19:07:21 +00002086 // Is it 'getelementptr %P, long 0' or 'getelementptr %P'
Chris Lattner113f4f42002-06-25 16:13:24 +00002087 // If so, eliminate the noop.
Chris Lattner8d0bacb2004-02-22 05:25:17 +00002088 if (GEP.getNumOperands() == 1)
2089 return ReplaceInstUsesWith(GEP, GEP.getOperand(0));
2090
2091 bool HasZeroPointerIndex = false;
2092 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
2093 HasZeroPointerIndex = C->isNullValue();
2094
2095 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
Chris Lattnere6794492002-08-12 21:17:25 +00002096 return ReplaceInstUsesWith(GEP, GEP.getOperand(0));
Chris Lattner48a44f72002-05-02 17:06:02 +00002097
Chris Lattnerae7a0d32002-08-02 19:29:35 +00002098 // Combine Indices - If the source pointer to this getelementptr instruction
2099 // is a getelementptr instruction, combine the indices of the two
2100 // getelementptr instructions into a single instruction.
2101 //
Chris Lattnerc59af1d2002-08-17 22:21:59 +00002102 if (GetElementPtrInst *Src = dyn_cast<GetElementPtrInst>(GEP.getOperand(0))) {
Chris Lattnerae7a0d32002-08-02 19:29:35 +00002103 std::vector<Value *> Indices;
Chris Lattnerca081252001-12-14 16:52:21 +00002104
Chris Lattnerae7a0d32002-08-02 19:29:35 +00002105 // Can we combine the two pointer arithmetics offsets?
Chris Lattner471bd762003-05-22 19:07:21 +00002106 if (Src->getNumOperands() == 2 && isa<Constant>(Src->getOperand(1)) &&
2107 isa<Constant>(GEP.getOperand(1))) {
Chris Lattner235af562003-03-05 22:33:14 +00002108 // Replace: gep (gep %P, long C1), long C2, ...
2109 // With: gep %P, long (C1+C2), ...
Chris Lattner34428442003-05-27 16:40:51 +00002110 Value *Sum = ConstantExpr::get(Instruction::Add,
2111 cast<Constant>(Src->getOperand(1)),
2112 cast<Constant>(GEP.getOperand(1)));
Chris Lattner235af562003-03-05 22:33:14 +00002113 assert(Sum && "Constant folding of longs failed!?");
2114 GEP.setOperand(0, Src->getOperand(0));
2115 GEP.setOperand(1, Sum);
2116 AddUsesToWorkList(*Src); // Reduce use count of Src
2117 return &GEP;
Chris Lattner471bd762003-05-22 19:07:21 +00002118 } else if (Src->getNumOperands() == 2) {
Chris Lattner235af562003-03-05 22:33:14 +00002119 // Replace: gep (gep %P, long B), long A, ...
2120 // With: T = long A+B; gep %P, T, ...
2121 //
2122 Value *Sum = BinaryOperator::create(Instruction::Add, Src->getOperand(1),
2123 GEP.getOperand(1),
2124 Src->getName()+".sum", &GEP);
2125 GEP.setOperand(0, Src->getOperand(0));
2126 GEP.setOperand(1, Sum);
2127 WorkList.push_back(cast<Instruction>(Sum));
2128 return &GEP;
Chris Lattner5d606a02002-11-04 16:43:32 +00002129 } else if (*GEP.idx_begin() == Constant::getNullValue(Type::LongTy) &&
Chris Lattnera8339e32002-09-17 21:05:42 +00002130 Src->getNumOperands() != 1) {
Chris Lattnerae7a0d32002-08-02 19:29:35 +00002131 // Otherwise we can do the fold if the first index of the GEP is a zero
2132 Indices.insert(Indices.end(), Src->idx_begin(), Src->idx_end());
2133 Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
Chris Lattner5d606a02002-11-04 16:43:32 +00002134 } else if (Src->getOperand(Src->getNumOperands()-1) ==
2135 Constant::getNullValue(Type::LongTy)) {
2136 // If the src gep ends with a constant array index, merge this get into
2137 // it, even if we have a non-zero array index.
2138 Indices.insert(Indices.end(), Src->idx_begin(), Src->idx_end()-1);
2139 Indices.insert(Indices.end(), GEP.idx_begin(), GEP.idx_end());
Chris Lattnerae7a0d32002-08-02 19:29:35 +00002140 }
2141
2142 if (!Indices.empty())
2143 return new GetElementPtrInst(Src->getOperand(0), Indices, GEP.getName());
Chris Lattnerc59af1d2002-08-17 22:21:59 +00002144
2145 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(GEP.getOperand(0))) {
2146 // GEP of global variable. If all of the indices for this GEP are
2147 // constants, we can promote this to a constexpr instead of an instruction.
2148
2149 // Scan for nonconstants...
2150 std::vector<Constant*> Indices;
2151 User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
2152 for (; I != E && isa<Constant>(*I); ++I)
2153 Indices.push_back(cast<Constant>(*I));
2154
2155 if (I == E) { // If they are all constants...
Chris Lattner46b3d302003-04-16 22:40:51 +00002156 Constant *CE =
Chris Lattnerc59af1d2002-08-17 22:21:59 +00002157 ConstantExpr::getGetElementPtr(ConstantPointerRef::get(GV), Indices);
2158
2159 // Replace all uses of the GEP with the new constexpr...
2160 return ReplaceInstUsesWith(GEP, CE);
2161 }
Chris Lattner8d0bacb2004-02-22 05:25:17 +00002162 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(GEP.getOperand(0))) {
2163 if (CE->getOpcode() == Instruction::Cast) {
2164 if (HasZeroPointerIndex) {
2165 // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
2166 // into : GEP [10 x ubyte]* X, long 0, ...
2167 //
2168 // This occurs when the program declares an array extern like "int X[];"
2169 //
2170 Constant *X = CE->getOperand(0);
2171 const PointerType *CPTy = cast<PointerType>(CE->getType());
2172 if (const PointerType *XTy = dyn_cast<PointerType>(X->getType()))
2173 if (const ArrayType *XATy =
2174 dyn_cast<ArrayType>(XTy->getElementType()))
2175 if (const ArrayType *CATy =
2176 dyn_cast<ArrayType>(CPTy->getElementType()))
2177 if (CATy->getElementType() == XATy->getElementType()) {
2178 // At this point, we know that the cast source type is a pointer
2179 // to an array of the same type as the destination pointer
2180 // array. Because the array type is never stepped over (there
2181 // is a leading zero) we can fold the cast into this GEP.
2182 GEP.setOperand(0, X);
2183 return &GEP;
2184 }
2185 }
2186 }
Chris Lattnerca081252001-12-14 16:52:21 +00002187 }
2188
Chris Lattnerca081252001-12-14 16:52:21 +00002189 return 0;
2190}
2191
Chris Lattner1085bdf2002-11-04 16:18:53 +00002192Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
2193 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
2194 if (AI.isArrayAllocation()) // Check C != 1
2195 if (const ConstantUInt *C = dyn_cast<ConstantUInt>(AI.getArraySize())) {
2196 const Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getValue());
Chris Lattnera2620ac2002-11-09 00:49:43 +00002197 AllocationInst *New = 0;
Chris Lattner1085bdf2002-11-04 16:18:53 +00002198
2199 // Create and insert the replacement instruction...
2200 if (isa<MallocInst>(AI))
2201 New = new MallocInst(NewTy, 0, AI.getName(), &AI);
Chris Lattnera2620ac2002-11-09 00:49:43 +00002202 else {
2203 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
Chris Lattner1085bdf2002-11-04 16:18:53 +00002204 New = new AllocaInst(NewTy, 0, AI.getName(), &AI);
Chris Lattnera2620ac2002-11-09 00:49:43 +00002205 }
Chris Lattner1085bdf2002-11-04 16:18:53 +00002206
2207 // Scan to the end of the allocation instructions, to skip over a block of
2208 // allocas if possible...
2209 //
2210 BasicBlock::iterator It = New;
2211 while (isa<AllocationInst>(*It)) ++It;
2212
2213 // Now that I is pointing to the first non-allocation-inst in the block,
2214 // insert our getelementptr instruction...
2215 //
2216 std::vector<Value*> Idx(2, Constant::getNullValue(Type::LongTy));
2217 Value *V = new GetElementPtrInst(New, Idx, New->getName()+".sub", It);
2218
2219 // Now make everything use the getelementptr instead of the original
2220 // allocation.
2221 ReplaceInstUsesWith(AI, V);
2222 return &AI;
2223 }
2224 return 0;
2225}
2226
Chris Lattner8427bff2003-12-07 01:24:23 +00002227Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
2228 Value *Op = FI.getOperand(0);
2229
2230 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
2231 if (CastInst *CI = dyn_cast<CastInst>(Op))
2232 if (isa<PointerType>(CI->getOperand(0)->getType())) {
2233 FI.setOperand(0, CI->getOperand(0));
2234 return &FI;
2235 }
2236
2237 return 0;
2238}
2239
2240
Chris Lattner0f1d8a32003-06-26 05:06:25 +00002241/// GetGEPGlobalInitializer - Given a constant, and a getelementptr
2242/// constantexpr, return the constant value being addressed by the constant
2243/// expression, or null if something is funny.
2244///
2245static Constant *GetGEPGlobalInitializer(Constant *C, ConstantExpr *CE) {
2246 if (CE->getOperand(1) != Constant::getNullValue(Type::LongTy))
2247 return 0; // Do not allow stepping over the value!
2248
2249 // Loop over all of the operands, tracking down which value we are
2250 // addressing...
2251 for (unsigned i = 2, e = CE->getNumOperands(); i != e; ++i)
2252 if (ConstantUInt *CU = dyn_cast<ConstantUInt>(CE->getOperand(i))) {
Chris Lattner76b2ff42004-02-15 05:55:15 +00002253 ConstantStruct *CS = dyn_cast<ConstantStruct>(C);
2254 if (CS == 0) return 0;
Chris Lattner0f1d8a32003-06-26 05:06:25 +00002255 if (CU->getValue() >= CS->getValues().size()) return 0;
2256 C = cast<Constant>(CS->getValues()[CU->getValue()]);
2257 } else if (ConstantSInt *CS = dyn_cast<ConstantSInt>(CE->getOperand(i))) {
Chris Lattner76b2ff42004-02-15 05:55:15 +00002258 ConstantArray *CA = dyn_cast<ConstantArray>(C);
2259 if (CA == 0) return 0;
Chris Lattner0f1d8a32003-06-26 05:06:25 +00002260 if ((uint64_t)CS->getValue() >= CA->getValues().size()) return 0;
2261 C = cast<Constant>(CA->getValues()[CS->getValue()]);
2262 } else
2263 return 0;
2264 return C;
2265}
2266
2267Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
2268 Value *Op = LI.getOperand(0);
Chris Lattner7e8af382004-01-12 04:13:56 +00002269 if (LI.isVolatile()) return 0;
2270
Chris Lattner0f1d8a32003-06-26 05:06:25 +00002271 if (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(Op))
2272 Op = CPR->getValue();
2273
2274 // Instcombine load (constant global) into the value loaded...
2275 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
Chris Lattnerbdb0ce02003-07-22 21:46:59 +00002276 if (GV->isConstant() && !GV->isExternal())
Chris Lattner0f1d8a32003-06-26 05:06:25 +00002277 return ReplaceInstUsesWith(LI, GV->getInitializer());
2278
2279 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded...
2280 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
2281 if (CE->getOpcode() == Instruction::GetElementPtr)
2282 if (ConstantPointerRef *G=dyn_cast<ConstantPointerRef>(CE->getOperand(0)))
2283 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(G->getValue()))
Chris Lattnerbdb0ce02003-07-22 21:46:59 +00002284 if (GV->isConstant() && !GV->isExternal())
Chris Lattner0f1d8a32003-06-26 05:06:25 +00002285 if (Constant *V = GetGEPGlobalInitializer(GV->getInitializer(), CE))
2286 return ReplaceInstUsesWith(LI, V);
2287 return 0;
2288}
2289
2290
Chris Lattner9eef8a72003-06-04 04:46:00 +00002291Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
2292 // Change br (not X), label True, label False to: br X, label False, True
Chris Lattner45789ac2003-06-05 20:12:51 +00002293 if (BI.isConditional() && !isa<Constant>(BI.getCondition()))
Chris Lattnere967b342003-06-04 05:10:11 +00002294 if (Value *V = dyn_castNotVal(BI.getCondition())) {
2295 BasicBlock *TrueDest = BI.getSuccessor(0);
2296 BasicBlock *FalseDest = BI.getSuccessor(1);
2297 // Swap Destinations and condition...
2298 BI.setCondition(V);
2299 BI.setSuccessor(0, FalseDest);
2300 BI.setSuccessor(1, TrueDest);
2301 return &BI;
2302 }
Chris Lattner9eef8a72003-06-04 04:46:00 +00002303 return 0;
2304}
Chris Lattner1085bdf2002-11-04 16:18:53 +00002305
Chris Lattnerca081252001-12-14 16:52:21 +00002306
Chris Lattner99f48c62002-09-02 04:59:56 +00002307void InstCombiner::removeFromWorkList(Instruction *I) {
2308 WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
2309 WorkList.end());
2310}
2311
Chris Lattner113f4f42002-06-25 16:13:24 +00002312bool InstCombiner::runOnFunction(Function &F) {
Chris Lattner260ab202002-04-18 17:39:14 +00002313 bool Changed = false;
Chris Lattnerf4ad1652003-11-02 05:57:39 +00002314 TD = &getAnalysis<TargetData>();
Chris Lattnerca081252001-12-14 16:52:21 +00002315
Chris Lattner260ab202002-04-18 17:39:14 +00002316 WorkList.insert(WorkList.end(), inst_begin(F), inst_end(F));
Chris Lattnerca081252001-12-14 16:52:21 +00002317
2318 while (!WorkList.empty()) {
2319 Instruction *I = WorkList.back(); // Get an instruction from the worklist
2320 WorkList.pop_back();
2321
Misha Brukman632df282002-10-29 23:06:16 +00002322 // Check to see if we can DCE or ConstantPropagate the instruction...
Chris Lattner99f48c62002-09-02 04:59:56 +00002323 // Check to see if we can DIE the instruction...
2324 if (isInstructionTriviallyDead(I)) {
2325 // Add operands to the worklist...
Chris Lattnere8ed4ef2003-10-06 17:11:01 +00002326 if (I->getNumOperands() < 4)
2327 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
2328 if (Instruction *Op = dyn_cast<Instruction>(I->getOperand(i)))
2329 WorkList.push_back(Op);
Chris Lattner99f48c62002-09-02 04:59:56 +00002330 ++NumDeadInst;
Chris Lattnere8ed4ef2003-10-06 17:11:01 +00002331
2332 I->getParent()->getInstList().erase(I);
2333 removeFromWorkList(I);
2334 continue;
2335 }
Chris Lattner99f48c62002-09-02 04:59:56 +00002336
Misha Brukman632df282002-10-29 23:06:16 +00002337 // Instruction isn't dead, see if we can constant propagate it...
Chris Lattner99f48c62002-09-02 04:59:56 +00002338 if (Constant *C = ConstantFoldInstruction(I)) {
2339 // Add operands to the worklist...
2340 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
2341 if (Instruction *Op = dyn_cast<Instruction>(I->getOperand(i)))
2342 WorkList.push_back(Op);
Chris Lattnerc6509f42002-12-05 22:41:53 +00002343 ReplaceInstUsesWith(*I, C);
2344
Chris Lattner99f48c62002-09-02 04:59:56 +00002345 ++NumConstProp;
Chris Lattnere8ed4ef2003-10-06 17:11:01 +00002346 I->getParent()->getInstList().erase(I);
Chris Lattner800aaaf2003-10-07 15:17:02 +00002347 removeFromWorkList(I);
Chris Lattnere8ed4ef2003-10-06 17:11:01 +00002348 continue;
Chris Lattner99f48c62002-09-02 04:59:56 +00002349 }
Chris Lattnere8ed4ef2003-10-06 17:11:01 +00002350
Chris Lattnerca081252001-12-14 16:52:21 +00002351 // Now that we have an instruction, try combining it to simplify it...
Chris Lattnerae7a0d32002-08-02 19:29:35 +00002352 if (Instruction *Result = visit(*I)) {
Chris Lattner0b18c1d2002-05-10 15:38:35 +00002353 ++NumCombined;
Chris Lattner260ab202002-04-18 17:39:14 +00002354 // Should we replace the old instruction with a new one?
Chris Lattner053c0932002-05-14 15:24:07 +00002355 if (Result != I) {
2356 // Instructions can end up on the worklist more than once. Make sure
2357 // we do not process an instruction that has been deleted.
Chris Lattner99f48c62002-09-02 04:59:56 +00002358 removeFromWorkList(I);
Chris Lattnere8ed4ef2003-10-06 17:11:01 +00002359
2360 // Move the name to the new instruction first...
2361 std::string OldName = I->getName(); I->setName("");
Chris Lattner950fc782003-10-07 22:58:41 +00002362 Result->setName(OldName);
Chris Lattnere8ed4ef2003-10-06 17:11:01 +00002363
2364 // Insert the new instruction into the basic block...
2365 BasicBlock *InstParent = I->getParent();
2366 InstParent->getInstList().insert(I, Result);
2367
2368 // Everything uses the new instruction now...
2369 I->replaceAllUsesWith(Result);
2370
2371 // Erase the old instruction.
2372 InstParent->getInstList().erase(I);
Chris Lattner113f4f42002-06-25 16:13:24 +00002373 } else {
Chris Lattnerae7a0d32002-08-02 19:29:35 +00002374 BasicBlock::iterator II = I;
2375
2376 // If the instruction was modified, it's possible that it is now dead.
2377 // if so, remove it.
2378 if (dceInstruction(II)) {
2379 // Instructions may end up in the worklist more than once. Erase them
2380 // all.
Chris Lattner99f48c62002-09-02 04:59:56 +00002381 removeFromWorkList(I);
Chris Lattnerae7a0d32002-08-02 19:29:35 +00002382 Result = 0;
2383 }
Chris Lattner053c0932002-05-14 15:24:07 +00002384 }
Chris Lattner260ab202002-04-18 17:39:14 +00002385
Chris Lattnerae7a0d32002-08-02 19:29:35 +00002386 if (Result) {
2387 WorkList.push_back(Result);
2388 AddUsesToWorkList(*Result);
2389 }
Chris Lattner260ab202002-04-18 17:39:14 +00002390 Changed = true;
Chris Lattnerca081252001-12-14 16:52:21 +00002391 }
2392 }
2393
Chris Lattner260ab202002-04-18 17:39:14 +00002394 return Changed;
Chris Lattner04805fa2002-02-26 21:46:54 +00002395}
2396
Chris Lattner8427bff2003-12-07 01:24:23 +00002397Pass *llvm::createInstructionCombiningPass() {
Chris Lattner260ab202002-04-18 17:39:14 +00002398 return new InstCombiner();
Chris Lattner04805fa2002-02-26 21:46:54 +00002399}
Brian Gaeke960707c2003-11-11 22:41:34 +00002400