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Chris Lattner4fd56002002-05-08 22:19:27 +00001//===- Reassociate.cpp - Reassociate binary expressions -------------------===//
Misha Brukmanfd939082005-04-21 23:48:37 +00002//
John Criswellb576c942003-10-20 19:43:21 +00003// The LLVM Compiler Infrastructure
4//
Chris Lattner4ee451d2007-12-29 20:36:04 +00005// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
Misha Brukmanfd939082005-04-21 23:48:37 +00007//
John Criswellb576c942003-10-20 19:43:21 +00008//===----------------------------------------------------------------------===//
Chris Lattner4fd56002002-05-08 22:19:27 +00009//
10// This pass reassociates commutative expressions in an order that is designed
Chris Lattner90461932010-01-01 00:04:26 +000011// to promote better constant propagation, GCSE, LICM, PRE, etc.
Chris Lattner4fd56002002-05-08 22:19:27 +000012//
13// For example: 4 + (x + 5) -> x + (4 + 5)
14//
Chris Lattner4fd56002002-05-08 22:19:27 +000015// In the implementation of this algorithm, constants are assigned rank = 0,
16// function arguments are rank = 1, and other values are assigned ranks
17// corresponding to the reverse post order traversal of current function
18// (starting at 2), which effectively gives values in deep loops higher rank
19// than values not in loops.
20//
21//===----------------------------------------------------------------------===//
22
Chris Lattner08b43922005-05-07 04:08:02 +000023#define DEBUG_TYPE "reassociate"
Chris Lattner4fd56002002-05-08 22:19:27 +000024#include "llvm/Transforms/Scalar.h"
Dan Gohmanfa0e6fa2011-03-10 19:51:54 +000025#include "llvm/Transforms/Utils/Local.h"
Chris Lattner0975ed52005-05-07 04:24:13 +000026#include "llvm/Constants.h"
Chris Lattnerae74f552006-04-28 04:14:49 +000027#include "llvm/DerivedTypes.h"
Chris Lattner4fd56002002-05-08 22:19:27 +000028#include "llvm/Function.h"
Misha Brukmand8e1eea2004-07-29 17:05:13 +000029#include "llvm/Instructions.h"
Dale Johannesen03afd022009-03-06 01:41:59 +000030#include "llvm/IntrinsicInst.h"
Chris Lattner4fd56002002-05-08 22:19:27 +000031#include "llvm/Pass.h"
Chris Lattnerc9fd0972005-05-08 20:09:57 +000032#include "llvm/Assembly/Writer.h"
Chris Lattner4fd56002002-05-08 22:19:27 +000033#include "llvm/Support/CFG.h"
Reid Spencer551ccae2004-09-01 22:55:40 +000034#include "llvm/Support/Debug.h"
Chris Lattnerd3c7b732009-03-31 22:13:29 +000035#include "llvm/Support/ValueHandle.h"
Chris Lattnerbdff5482009-08-23 04:37:46 +000036#include "llvm/Support/raw_ostream.h"
Reid Spencer551ccae2004-09-01 22:55:40 +000037#include "llvm/ADT/PostOrderIterator.h"
38#include "llvm/ADT/Statistic.h"
Chris Lattnerec531232009-12-31 07:33:14 +000039#include "llvm/ADT/DenseMap.h"
Chris Lattnerc0649ac2005-05-07 21:59:39 +000040#include <algorithm>
Chris Lattnerd7456022004-01-09 06:02:20 +000041using namespace llvm;
Brian Gaeked0fde302003-11-11 22:41:34 +000042
Chris Lattner0e5f4992006-12-19 21:40:18 +000043STATISTIC(NumLinear , "Number of insts linearized");
44STATISTIC(NumChanged, "Number of insts reassociated");
45STATISTIC(NumAnnihil, "Number of expr tree annihilated");
46STATISTIC(NumFactor , "Number of multiplies factored");
Chris Lattnera92f6962002-10-01 22:38:41 +000047
Chris Lattner0e5f4992006-12-19 21:40:18 +000048namespace {
Chris Lattner3e8b6632009-09-02 06:11:42 +000049 struct ValueEntry {
Chris Lattnerc0649ac2005-05-07 21:59:39 +000050 unsigned Rank;
51 Value *Op;
52 ValueEntry(unsigned R, Value *O) : Rank(R), Op(O) {}
53 };
54 inline bool operator<(const ValueEntry &LHS, const ValueEntry &RHS) {
55 return LHS.Rank > RHS.Rank; // Sort so that highest rank goes to start.
56 }
Chris Lattnere5022fe2006-03-04 09:31:13 +000057}
Chris Lattnerc0649ac2005-05-07 21:59:39 +000058
Devang Patel50cacb22008-11-21 21:00:20 +000059#ifndef NDEBUG
Chris Lattnere5022fe2006-03-04 09:31:13 +000060/// PrintOps - Print out the expression identified in the Ops list.
61///
Chris Lattner9f7b7082009-12-31 18:40:32 +000062static void PrintOps(Instruction *I, const SmallVectorImpl<ValueEntry> &Ops) {
Chris Lattnere5022fe2006-03-04 09:31:13 +000063 Module *M = I->getParent()->getParent()->getParent();
David Greenea1fa76c2010-01-05 01:27:24 +000064 dbgs() << Instruction::getOpcodeName(I->getOpcode()) << " "
Chris Lattner1befe642009-12-31 07:17:37 +000065 << *Ops[0].Op->getType() << '\t';
Chris Lattner7de3b5d2008-08-19 04:45:19 +000066 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
David Greenea1fa76c2010-01-05 01:27:24 +000067 dbgs() << "[ ";
68 WriteAsOperand(dbgs(), Ops[i].Op, false, M);
69 dbgs() << ", #" << Ops[i].Rank << "] ";
Chris Lattner7de3b5d2008-08-19 04:45:19 +000070 }
Chris Lattnere5022fe2006-03-04 09:31:13 +000071}
Devang Patel59500c82008-11-21 20:00:59 +000072#endif
Chris Lattnere5022fe2006-03-04 09:31:13 +000073
Dan Gohman844731a2008-05-13 00:00:25 +000074namespace {
Chris Lattner3e8b6632009-09-02 06:11:42 +000075 class Reassociate : public FunctionPass {
Chris Lattnerf55e7f52010-01-01 00:01:34 +000076 DenseMap<BasicBlock*, unsigned> RankMap;
77 DenseMap<AssertingVH<>, unsigned> ValueRankMap;
Devang Patel16195602011-07-29 19:00:35 +000078 DenseMap<Value *, DbgValueInst *> DbgValues;
Dan Gohmandac5dba2011-04-12 00:11:56 +000079 SmallVector<WeakVH, 8> RedoInsts;
Dan Gohmanfa0e6fa2011-03-10 19:51:54 +000080 SmallVector<WeakVH, 8> DeadInsts;
Chris Lattnerc0649ac2005-05-07 21:59:39 +000081 bool MadeChange;
Chris Lattner4fd56002002-05-08 22:19:27 +000082 public:
Nick Lewyckyecd94c82007-05-06 13:37:16 +000083 static char ID; // Pass identification, replacement for typeid
Owen Anderson081c34b2010-10-19 17:21:58 +000084 Reassociate() : FunctionPass(ID) {
85 initializeReassociatePass(*PassRegistry::getPassRegistry());
86 }
Devang Patel794fd752007-05-01 21:15:47 +000087
Chris Lattner7e708292002-06-25 16:13:24 +000088 bool runOnFunction(Function &F);
Chris Lattner4fd56002002-05-08 22:19:27 +000089
90 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
Chris Lattnercb2610e2002-10-21 20:00:28 +000091 AU.setPreservesCFG();
Chris Lattner4fd56002002-05-08 22:19:27 +000092 }
93 private:
Chris Lattner7e708292002-06-25 16:13:24 +000094 void BuildRankMap(Function &F);
Chris Lattner4fd56002002-05-08 22:19:27 +000095 unsigned getRank(Value *V);
Chris Lattner69e98e22009-12-31 19:24:52 +000096 Value *ReassociateExpression(BinaryOperator *I);
Chris Lattner9f7b7082009-12-31 18:40:32 +000097 void RewriteExprTree(BinaryOperator *I, SmallVectorImpl<ValueEntry> &Ops,
Chris Lattnere9efecb2006-03-14 16:04:29 +000098 unsigned Idx = 0);
Chris Lattner9f7b7082009-12-31 18:40:32 +000099 Value *OptimizeExpression(BinaryOperator *I,
100 SmallVectorImpl<ValueEntry> &Ops);
101 Value *OptimizeAdd(Instruction *I, SmallVectorImpl<ValueEntry> &Ops);
102 void LinearizeExprTree(BinaryOperator *I, SmallVectorImpl<ValueEntry> &Ops);
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000103 void LinearizeExpr(BinaryOperator *I);
Chris Lattnere5022fe2006-03-04 09:31:13 +0000104 Value *RemoveFactorFromExpression(Value *V, Value *Factor);
Dan Gohmandac5dba2011-04-12 00:11:56 +0000105 void ReassociateInst(BasicBlock::iterator &BBI);
Chris Lattnere5022fe2006-03-04 09:31:13 +0000106
107 void RemoveDeadBinaryOp(Value *V);
Devang Patel16195602011-07-29 19:00:35 +0000108
109 /// collectDbgValues - Collect all llvm.dbg.value intrinsics.
110 void collectDbgValues(Function &F);
Chris Lattner4fd56002002-05-08 22:19:27 +0000111 };
112}
113
Dan Gohman844731a2008-05-13 00:00:25 +0000114char Reassociate::ID = 0;
Owen Andersond13db2c2010-07-21 22:09:45 +0000115INITIALIZE_PASS(Reassociate, "reassociate",
Owen Andersonce665bd2010-10-07 22:25:06 +0000116 "Reassociate expressions", false, false)
Dan Gohman844731a2008-05-13 00:00:25 +0000117
Brian Gaeked0fde302003-11-11 22:41:34 +0000118// Public interface to the Reassociate pass
Chris Lattnerd7456022004-01-09 06:02:20 +0000119FunctionPass *llvm::createReassociatePass() { return new Reassociate(); }
Chris Lattner4fd56002002-05-08 22:19:27 +0000120
Chris Lattnere5022fe2006-03-04 09:31:13 +0000121void Reassociate::RemoveDeadBinaryOp(Value *V) {
Reid Spencere4d87aa2006-12-23 06:05:41 +0000122 Instruction *Op = dyn_cast<Instruction>(V);
Dan Gohmanfa0e6fa2011-03-10 19:51:54 +0000123 if (!Op || !isa<BinaryOperator>(Op))
Reid Spencere4d87aa2006-12-23 06:05:41 +0000124 return;
Chris Lattnere5022fe2006-03-04 09:31:13 +0000125
Reid Spencere4d87aa2006-12-23 06:05:41 +0000126 Value *LHS = Op->getOperand(0), *RHS = Op->getOperand(1);
Chris Lattner69e98e22009-12-31 19:24:52 +0000127
128 ValueRankMap.erase(Op);
Dan Gohmanfa0e6fa2011-03-10 19:51:54 +0000129 DeadInsts.push_back(Op);
Chris Lattnere5022fe2006-03-04 09:31:13 +0000130 RemoveDeadBinaryOp(LHS);
131 RemoveDeadBinaryOp(RHS);
132}
133
Chris Lattner9c723192005-05-08 20:57:04 +0000134
135static bool isUnmovableInstruction(Instruction *I) {
136 if (I->getOpcode() == Instruction::PHI ||
137 I->getOpcode() == Instruction::Alloca ||
138 I->getOpcode() == Instruction::Load ||
Chris Lattner9c723192005-05-08 20:57:04 +0000139 I->getOpcode() == Instruction::Invoke ||
Dale Johannesen03afd022009-03-06 01:41:59 +0000140 (I->getOpcode() == Instruction::Call &&
141 !isa<DbgInfoIntrinsic>(I)) ||
Reid Spencer1628cec2006-10-26 06:15:43 +0000142 I->getOpcode() == Instruction::UDiv ||
143 I->getOpcode() == Instruction::SDiv ||
144 I->getOpcode() == Instruction::FDiv ||
Reid Spencer0a783f72006-11-02 01:53:59 +0000145 I->getOpcode() == Instruction::URem ||
146 I->getOpcode() == Instruction::SRem ||
147 I->getOpcode() == Instruction::FRem)
Chris Lattner9c723192005-05-08 20:57:04 +0000148 return true;
149 return false;
150}
151
Chris Lattner7e708292002-06-25 16:13:24 +0000152void Reassociate::BuildRankMap(Function &F) {
Chris Lattner6007cb62003-08-12 20:14:27 +0000153 unsigned i = 2;
Chris Lattnerfb5be092003-08-13 16:16:26 +0000154
155 // Assign distinct ranks to function arguments
Chris Lattnere4d5c442005-03-15 04:54:21 +0000156 for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I)
Chris Lattnerd3c7b732009-03-31 22:13:29 +0000157 ValueRankMap[&*I] = ++i;
Chris Lattnerfb5be092003-08-13 16:16:26 +0000158
Chris Lattner7e708292002-06-25 16:13:24 +0000159 ReversePostOrderTraversal<Function*> RPOT(&F);
Chris Lattner4fd56002002-05-08 22:19:27 +0000160 for (ReversePostOrderTraversal<Function*>::rpo_iterator I = RPOT.begin(),
Chris Lattner9c723192005-05-08 20:57:04 +0000161 E = RPOT.end(); I != E; ++I) {
162 BasicBlock *BB = *I;
163 unsigned BBRank = RankMap[BB] = ++i << 16;
164
165 // Walk the basic block, adding precomputed ranks for any instructions that
166 // we cannot move. This ensures that the ranks for these instructions are
167 // all different in the block.
168 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
169 if (isUnmovableInstruction(I))
Chris Lattnerd3c7b732009-03-31 22:13:29 +0000170 ValueRankMap[&*I] = ++BBRank;
Chris Lattner9c723192005-05-08 20:57:04 +0000171 }
Chris Lattner4fd56002002-05-08 22:19:27 +0000172}
173
174unsigned Reassociate::getRank(Value *V) {
Chris Lattner08b43922005-05-07 04:08:02 +0000175 Instruction *I = dyn_cast<Instruction>(V);
Chris Lattnerf55e7f52010-01-01 00:01:34 +0000176 if (I == 0) {
177 if (isa<Argument>(V)) return ValueRankMap[V]; // Function argument.
178 return 0; // Otherwise it's a global or constant, rank 0.
179 }
Chris Lattner4fd56002002-05-08 22:19:27 +0000180
Chris Lattnerf55e7f52010-01-01 00:01:34 +0000181 if (unsigned Rank = ValueRankMap[I])
182 return Rank; // Rank already known?
Jeff Cohen00b168892005-07-27 06:12:32 +0000183
Chris Lattner08b43922005-05-07 04:08:02 +0000184 // If this is an expression, return the 1+MAX(rank(LHS), rank(RHS)) so that
185 // we can reassociate expressions for code motion! Since we do not recurse
186 // for PHI nodes, we cannot have infinite recursion here, because there
187 // cannot be loops in the value graph that do not go through PHI nodes.
Chris Lattner08b43922005-05-07 04:08:02 +0000188 unsigned Rank = 0, MaxRank = RankMap[I->getParent()];
189 for (unsigned i = 0, e = I->getNumOperands();
190 i != e && Rank != MaxRank; ++i)
191 Rank = std::max(Rank, getRank(I->getOperand(i)));
Jeff Cohen00b168892005-07-27 06:12:32 +0000192
Chris Lattnercc8a2b92005-05-08 00:08:33 +0000193 // If this is a not or neg instruction, do not count it for rank. This
194 // assures us that X and ~X will have the same rank.
Duncan Sandsb0bc6c32010-02-15 16:12:20 +0000195 if (!I->getType()->isIntegerTy() ||
Owen Andersonfa82b6e2009-07-13 22:18:28 +0000196 (!BinaryOperator::isNot(I) && !BinaryOperator::isNeg(I)))
Chris Lattnercc8a2b92005-05-08 00:08:33 +0000197 ++Rank;
198
David Greenea1fa76c2010-01-05 01:27:24 +0000199 //DEBUG(dbgs() << "Calculated Rank[" << V->getName() << "] = "
Chris Lattnerbdff5482009-08-23 04:37:46 +0000200 // << Rank << "\n");
Jeff Cohen00b168892005-07-27 06:12:32 +0000201
Chris Lattnerf55e7f52010-01-01 00:01:34 +0000202 return ValueRankMap[I] = Rank;
Chris Lattner4fd56002002-05-08 22:19:27 +0000203}
204
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000205/// isReassociableOp - Return true if V is an instruction of the specified
206/// opcode and if it only has one use.
207static BinaryOperator *isReassociableOp(Value *V, unsigned Opcode) {
Chris Lattnere9efecb2006-03-14 16:04:29 +0000208 if ((V->hasOneUse() || V->use_empty()) && isa<Instruction>(V) &&
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000209 cast<Instruction>(V)->getOpcode() == Opcode)
210 return cast<BinaryOperator>(V);
211 return 0;
212}
Chris Lattner4fd56002002-05-08 22:19:27 +0000213
Chris Lattnerf33151a2005-05-08 21:28:52 +0000214/// LowerNegateToMultiply - Replace 0-X with X*-1.
215///
Dale Johannesenf4978e22009-03-19 17:22:53 +0000216static Instruction *LowerNegateToMultiply(Instruction *Neg,
Chris Lattnerf55e7f52010-01-01 00:01:34 +0000217 DenseMap<AssertingVH<>, unsigned> &ValueRankMap) {
Owen Andersona7235ea2009-07-31 20:28:14 +0000218 Constant *Cst = Constant::getAllOnesValue(Neg->getType());
Chris Lattnerf33151a2005-05-08 21:28:52 +0000219
Gabor Greif7cbd8a32008-05-16 19:29:10 +0000220 Instruction *Res = BinaryOperator::CreateMul(Neg->getOperand(1), Cst, "",Neg);
Dale Johannesenf4978e22009-03-19 17:22:53 +0000221 ValueRankMap.erase(Neg);
Chris Lattner6934a042007-02-11 01:23:03 +0000222 Res->takeName(Neg);
Chris Lattnerf33151a2005-05-08 21:28:52 +0000223 Neg->replaceAllUsesWith(Res);
Devang Patel5367b232011-04-28 22:48:14 +0000224 Res->setDebugLoc(Neg->getDebugLoc());
Chris Lattnerf33151a2005-05-08 21:28:52 +0000225 Neg->eraseFromParent();
226 return Res;
227}
228
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000229// Given an expression of the form '(A+B)+(D+C)', turn it into '(((A+B)+C)+D)'.
230// Note that if D is also part of the expression tree that we recurse to
231// linearize it as well. Besides that case, this does not recurse into A,B, or
232// C.
233void Reassociate::LinearizeExpr(BinaryOperator *I) {
234 BinaryOperator *LHS = cast<BinaryOperator>(I->getOperand(0));
235 BinaryOperator *RHS = cast<BinaryOperator>(I->getOperand(1));
Jeff Cohen00b168892005-07-27 06:12:32 +0000236 assert(isReassociableOp(LHS, I->getOpcode()) &&
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000237 isReassociableOp(RHS, I->getOpcode()) &&
238 "Not an expression that needs linearization?");
Misha Brukmanfd939082005-04-21 23:48:37 +0000239
David Greenea1fa76c2010-01-05 01:27:24 +0000240 DEBUG(dbgs() << "Linear" << *LHS << '\n' << *RHS << '\n' << *I << '\n');
Chris Lattner4fd56002002-05-08 22:19:27 +0000241
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000242 // Move the RHS instruction to live immediately before I, avoiding breaking
243 // dominator properties.
Chris Lattner4bc5f802005-08-08 19:11:57 +0000244 RHS->moveBefore(I);
Chris Lattnere4b73042002-10-31 17:12:59 +0000245
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000246 // Move operands around to do the linearization.
247 I->setOperand(1, RHS->getOperand(0));
248 RHS->setOperand(0, LHS);
249 I->setOperand(0, RHS);
Jeff Cohen00b168892005-07-27 06:12:32 +0000250
Dan Gohman46985a12011-02-02 02:02:34 +0000251 // Conservatively clear all the optional flags, which may not hold
252 // after the reassociation.
253 I->clearSubclassOptionalData();
254 LHS->clearSubclassOptionalData();
255 RHS->clearSubclassOptionalData();
256
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000257 ++NumLinear;
258 MadeChange = true;
David Greenea1fa76c2010-01-05 01:27:24 +0000259 DEBUG(dbgs() << "Linearized: " << *I << '\n');
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000260
261 // If D is part of this expression tree, tail recurse.
262 if (isReassociableOp(I->getOperand(1), I->getOpcode()))
263 LinearizeExpr(I);
264}
265
266
267/// LinearizeExprTree - Given an associative binary expression tree, traverse
268/// all of the uses putting it into canonical form. This forces a left-linear
Dan Gohmanf451cb82010-02-10 16:03:48 +0000269/// form of the expression (((a+b)+c)+d), and collects information about the
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000270/// rank of the non-tree operands.
271///
Chris Lattnere9efecb2006-03-14 16:04:29 +0000272/// NOTE: These intentionally destroys the expression tree operands (turning
273/// them into undef values) to reduce #uses of the values. This means that the
274/// caller MUST use something like RewriteExprTree to put the values back in.
275///
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000276void Reassociate::LinearizeExprTree(BinaryOperator *I,
Chris Lattner9f7b7082009-12-31 18:40:32 +0000277 SmallVectorImpl<ValueEntry> &Ops) {
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000278 Value *LHS = I->getOperand(0), *RHS = I->getOperand(1);
279 unsigned Opcode = I->getOpcode();
280
281 // First step, linearize the expression if it is in ((A+B)+(C+D)) form.
282 BinaryOperator *LHSBO = isReassociableOp(LHS, Opcode);
283 BinaryOperator *RHSBO = isReassociableOp(RHS, Opcode);
284
Chris Lattnerf33151a2005-05-08 21:28:52 +0000285 // If this is a multiply expression tree and it contains internal negations,
286 // transform them into multiplies by -1 so they can be reassociated.
287 if (I->getOpcode() == Instruction::Mul) {
Owen Andersonfa82b6e2009-07-13 22:18:28 +0000288 if (!LHSBO && LHS->hasOneUse() && BinaryOperator::isNeg(LHS)) {
Nick Lewyckye79fdde2009-11-14 07:25:54 +0000289 LHS = LowerNegateToMultiply(cast<Instruction>(LHS), ValueRankMap);
Chris Lattnerf33151a2005-05-08 21:28:52 +0000290 LHSBO = isReassociableOp(LHS, Opcode);
291 }
Owen Andersonfa82b6e2009-07-13 22:18:28 +0000292 if (!RHSBO && RHS->hasOneUse() && BinaryOperator::isNeg(RHS)) {
Nick Lewyckye79fdde2009-11-14 07:25:54 +0000293 RHS = LowerNegateToMultiply(cast<Instruction>(RHS), ValueRankMap);
Chris Lattnerf33151a2005-05-08 21:28:52 +0000294 RHSBO = isReassociableOp(RHS, Opcode);
295 }
296 }
297
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000298 if (!LHSBO) {
299 if (!RHSBO) {
300 // Neither the LHS or RHS as part of the tree, thus this is a leaf. As
301 // such, just remember these operands and their rank.
302 Ops.push_back(ValueEntry(getRank(LHS), LHS));
303 Ops.push_back(ValueEntry(getRank(RHS), RHS));
Chris Lattnere9efecb2006-03-14 16:04:29 +0000304
305 // Clear the leaves out.
Owen Anderson9e9a0d52009-07-30 23:03:37 +0000306 I->setOperand(0, UndefValue::get(I->getType()));
307 I->setOperand(1, UndefValue::get(I->getType()));
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000308 return;
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000309 }
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000310
311 // Turn X+(Y+Z) -> (Y+Z)+X
312 std::swap(LHSBO, RHSBO);
313 std::swap(LHS, RHS);
314 bool Success = !I->swapOperands();
315 assert(Success && "swapOperands failed");
316 Success = false;
317 MadeChange = true;
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000318 } else if (RHSBO) {
Dan Gohmanf451cb82010-02-10 16:03:48 +0000319 // Turn (A+B)+(C+D) -> (((A+B)+C)+D). This guarantees the RHS is not
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000320 // part of the expression tree.
321 LinearizeExpr(I);
322 LHS = LHSBO = cast<BinaryOperator>(I->getOperand(0));
323 RHS = I->getOperand(1);
324 RHSBO = 0;
Chris Lattner4fd56002002-05-08 22:19:27 +0000325 }
Misha Brukmanfd939082005-04-21 23:48:37 +0000326
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000327 // Okay, now we know that the LHS is a nested expression and that the RHS is
328 // not. Perform reassociation.
329 assert(!isReassociableOp(RHS, Opcode) && "LinearizeExpr failed!");
Chris Lattner4fd56002002-05-08 22:19:27 +0000330
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000331 // Move LHS right before I to make sure that the tree expression dominates all
332 // values.
Chris Lattner4bc5f802005-08-08 19:11:57 +0000333 LHSBO->moveBefore(I);
Chris Lattnere9608e32003-08-12 21:45:24 +0000334
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000335 // Linearize the expression tree on the LHS.
336 LinearizeExprTree(LHSBO, Ops);
Chris Lattnere4b73042002-10-31 17:12:59 +0000337
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000338 // Remember the RHS operand and its rank.
339 Ops.push_back(ValueEntry(getRank(RHS), RHS));
Chris Lattnere9efecb2006-03-14 16:04:29 +0000340
341 // Clear the RHS leaf out.
Owen Anderson9e9a0d52009-07-30 23:03:37 +0000342 I->setOperand(1, UndefValue::get(I->getType()));
Chris Lattner4fd56002002-05-08 22:19:27 +0000343}
344
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000345// RewriteExprTree - Now that the operands for this expression tree are
346// linearized and optimized, emit them in-order. This function is written to be
347// tail recursive.
Chris Lattnere9efecb2006-03-14 16:04:29 +0000348void Reassociate::RewriteExprTree(BinaryOperator *I,
Chris Lattner9f7b7082009-12-31 18:40:32 +0000349 SmallVectorImpl<ValueEntry> &Ops,
Chris Lattnere9efecb2006-03-14 16:04:29 +0000350 unsigned i) {
Devang Patel16195602011-07-29 19:00:35 +0000351 // If this operation was representing debug info of a value then it
352 // is no longer true, so remove the dbg.value instrinsic.
353 if (DbgValueInst *DVI = DbgValues.lookup(I))
354 DeadInsts.push_back(DVI);
355
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000356 if (i+2 == Ops.size()) {
357 if (I->getOperand(0) != Ops[i].Op ||
358 I->getOperand(1) != Ops[i+1].Op) {
Chris Lattnere5022fe2006-03-04 09:31:13 +0000359 Value *OldLHS = I->getOperand(0);
David Greenea1fa76c2010-01-05 01:27:24 +0000360 DEBUG(dbgs() << "RA: " << *I << '\n');
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000361 I->setOperand(0, Ops[i].Op);
362 I->setOperand(1, Ops[i+1].Op);
Dan Gohman46985a12011-02-02 02:02:34 +0000363
Chris Lattnerde1d8a52011-02-17 01:29:24 +0000364 // Clear all the optional flags, which may not hold after the
365 // reassociation if the expression involved more than just this operation.
366 if (Ops.size() != 2)
367 I->clearSubclassOptionalData();
Dan Gohman46985a12011-02-02 02:02:34 +0000368
David Greenea1fa76c2010-01-05 01:27:24 +0000369 DEBUG(dbgs() << "TO: " << *I << '\n');
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000370 MadeChange = true;
371 ++NumChanged;
Chris Lattnere5022fe2006-03-04 09:31:13 +0000372
373 // If we reassociated a tree to fewer operands (e.g. (1+a+2) -> (a+3)
374 // delete the extra, now dead, nodes.
375 RemoveDeadBinaryOp(OldLHS);
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000376 }
377 return;
378 }
379 assert(i+2 < Ops.size() && "Ops index out of range!");
380
381 if (I->getOperand(1) != Ops[i].Op) {
David Greenea1fa76c2010-01-05 01:27:24 +0000382 DEBUG(dbgs() << "RA: " << *I << '\n');
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000383 I->setOperand(1, Ops[i].Op);
Dan Gohman46985a12011-02-02 02:02:34 +0000384
385 // Conservatively clear all the optional flags, which may not hold
386 // after the reassociation.
387 I->clearSubclassOptionalData();
388
David Greenea1fa76c2010-01-05 01:27:24 +0000389 DEBUG(dbgs() << "TO: " << *I << '\n');
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000390 MadeChange = true;
391 ++NumChanged;
392 }
Chris Lattnere5022fe2006-03-04 09:31:13 +0000393
394 BinaryOperator *LHS = cast<BinaryOperator>(I->getOperand(0));
395 assert(LHS->getOpcode() == I->getOpcode() &&
396 "Improper expression tree!");
397
398 // Compactify the tree instructions together with each other to guarantee
399 // that the expression tree is dominated by all of Ops.
400 LHS->moveBefore(I);
Chris Lattnere9efecb2006-03-14 16:04:29 +0000401 RewriteExprTree(LHS, Ops, i+1);
Chris Lattnerc0649ac2005-05-07 21:59:39 +0000402}
403
404
Chris Lattner4fd56002002-05-08 22:19:27 +0000405
Chris Lattnera36e6c82002-05-16 04:37:07 +0000406// NegateValue - Insert instructions before the instruction pointed to by BI,
407// that computes the negative version of the value specified. The negative
408// version of the value is returned, and BI is left pointing at the instruction
409// that should be processed next by the reassociation pass.
410//
Nick Lewyckye79fdde2009-11-14 07:25:54 +0000411static Value *NegateValue(Value *V, Instruction *BI) {
Chris Lattner35239932009-12-31 20:34:32 +0000412 if (Constant *C = dyn_cast<Constant>(V))
413 return ConstantExpr::getNeg(C);
414
Chris Lattnera36e6c82002-05-16 04:37:07 +0000415 // We are trying to expose opportunity for reassociation. One of the things
416 // that we want to do to achieve this is to push a negation as deep into an
417 // expression chain as possible, to expose the add instructions. In practice,
418 // this means that we turn this:
419 // X = -(A+12+C+D) into X = -A + -12 + -C + -D = -12 + -A + -C + -D
420 // so that later, a: Y = 12+X could get reassociated with the -12 to eliminate
421 // the constants. We assume that instcombine will clean up the mess later if
Chris Lattner90461932010-01-01 00:04:26 +0000422 // we introduce tons of unnecessary negation instructions.
Chris Lattnera36e6c82002-05-16 04:37:07 +0000423 //
424 if (Instruction *I = dyn_cast<Instruction>(V))
Chris Lattnerfd059242003-10-15 16:48:29 +0000425 if (I->getOpcode() == Instruction::Add && I->hasOneUse()) {
Chris Lattner2cd85da2005-09-02 06:38:04 +0000426 // Push the negates through the add.
Nick Lewyckye79fdde2009-11-14 07:25:54 +0000427 I->setOperand(0, NegateValue(I->getOperand(0), BI));
428 I->setOperand(1, NegateValue(I->getOperand(1), BI));
Chris Lattnera36e6c82002-05-16 04:37:07 +0000429
Chris Lattner2cd85da2005-09-02 06:38:04 +0000430 // We must move the add instruction here, because the neg instructions do
431 // not dominate the old add instruction in general. By moving it, we are
432 // assured that the neg instructions we just inserted dominate the
433 // instruction we are about to insert after them.
Chris Lattnera36e6c82002-05-16 04:37:07 +0000434 //
Chris Lattner2cd85da2005-09-02 06:38:04 +0000435 I->moveBefore(BI);
436 I->setName(I->getName()+".neg");
437 return I;
Chris Lattnera36e6c82002-05-16 04:37:07 +0000438 }
Chris Lattner35239932009-12-31 20:34:32 +0000439
440 // Okay, we need to materialize a negated version of V with an instruction.
441 // Scan the use lists of V to see if we have one already.
442 for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
Gabor Greif110b75a2010-07-12 12:03:02 +0000443 User *U = *UI;
444 if (!BinaryOperator::isNeg(U)) continue;
Chris Lattner35239932009-12-31 20:34:32 +0000445
446 // We found one! Now we have to make sure that the definition dominates
447 // this use. We do this by moving it to the entry block (if it is a
448 // non-instruction value) or right after the definition. These negates will
449 // be zapped by reassociate later, so we don't need much finesse here.
Gabor Greif110b75a2010-07-12 12:03:02 +0000450 BinaryOperator *TheNeg = cast<BinaryOperator>(U);
Chris Lattner1c91fae2010-01-02 21:46:33 +0000451
452 // Verify that the negate is in this function, V might be a constant expr.
453 if (TheNeg->getParent()->getParent() != BI->getParent()->getParent())
454 continue;
Chris Lattner35239932009-12-31 20:34:32 +0000455
456 BasicBlock::iterator InsertPt;
457 if (Instruction *InstInput = dyn_cast<Instruction>(V)) {
458 if (InvokeInst *II = dyn_cast<InvokeInst>(InstInput)) {
459 InsertPt = II->getNormalDest()->begin();
460 } else {
461 InsertPt = InstInput;
462 ++InsertPt;
463 }
464 while (isa<PHINode>(InsertPt)) ++InsertPt;
465 } else {
466 InsertPt = TheNeg->getParent()->getParent()->getEntryBlock().begin();
467 }
468 TheNeg->moveBefore(InsertPt);
469 return TheNeg;
470 }
Chris Lattnera36e6c82002-05-16 04:37:07 +0000471
472 // Insert a 'neg' instruction that subtracts the value from zero to get the
473 // negation.
Dan Gohman4ae51262009-08-12 16:23:25 +0000474 return BinaryOperator::CreateNeg(V, V->getName() + ".neg", BI);
Chris Lattner08b43922005-05-07 04:08:02 +0000475}
476
Chris Lattner9bc5ed72008-02-17 20:44:51 +0000477/// ShouldBreakUpSubtract - Return true if we should break up this subtract of
478/// X-Y into (X + -Y).
Nick Lewyckye79fdde2009-11-14 07:25:54 +0000479static bool ShouldBreakUpSubtract(Instruction *Sub) {
Chris Lattner9bc5ed72008-02-17 20:44:51 +0000480 // If this is a negation, we can't split it up!
Owen Andersonfa82b6e2009-07-13 22:18:28 +0000481 if (BinaryOperator::isNeg(Sub))
Chris Lattner9bc5ed72008-02-17 20:44:51 +0000482 return false;
483
484 // Don't bother to break this up unless either the LHS is an associable add or
Chris Lattner0b0803a2008-02-17 20:51:26 +0000485 // subtract or if this is only used by one.
486 if (isReassociableOp(Sub->getOperand(0), Instruction::Add) ||
487 isReassociableOp(Sub->getOperand(0), Instruction::Sub))
Chris Lattner9bc5ed72008-02-17 20:44:51 +0000488 return true;
Chris Lattner0b0803a2008-02-17 20:51:26 +0000489 if (isReassociableOp(Sub->getOperand(1), Instruction::Add) ||
Chris Lattner5329bb22008-02-17 20:54:40 +0000490 isReassociableOp(Sub->getOperand(1), Instruction::Sub))
Chris Lattner9bc5ed72008-02-17 20:44:51 +0000491 return true;
Chris Lattner0b0803a2008-02-17 20:51:26 +0000492 if (Sub->hasOneUse() &&
493 (isReassociableOp(Sub->use_back(), Instruction::Add) ||
494 isReassociableOp(Sub->use_back(), Instruction::Sub)))
Chris Lattner9bc5ed72008-02-17 20:44:51 +0000495 return true;
496
497 return false;
498}
499
Chris Lattner08b43922005-05-07 04:08:02 +0000500/// BreakUpSubtract - If we have (X-Y), and if either X is an add, or if this is
501/// only used by an add, transform this into (X+(0-Y)) to promote better
502/// reassociation.
Nick Lewyckye79fdde2009-11-14 07:25:54 +0000503static Instruction *BreakUpSubtract(Instruction *Sub,
Chris Lattnerf55e7f52010-01-01 00:01:34 +0000504 DenseMap<AssertingVH<>, unsigned> &ValueRankMap) {
Chris Lattner90461932010-01-01 00:04:26 +0000505 // Convert a subtract into an add and a neg instruction. This allows sub
506 // instructions to be commuted with other add instructions.
Chris Lattner08b43922005-05-07 04:08:02 +0000507 //
Chris Lattner90461932010-01-01 00:04:26 +0000508 // Calculate the negative value of Operand 1 of the sub instruction,
509 // and set it as the RHS of the add instruction we just made.
Chris Lattner08b43922005-05-07 04:08:02 +0000510 //
Nick Lewyckye79fdde2009-11-14 07:25:54 +0000511 Value *NegVal = NegateValue(Sub->getOperand(1), Sub);
Chris Lattner08b43922005-05-07 04:08:02 +0000512 Instruction *New =
Gabor Greif7cbd8a32008-05-16 19:29:10 +0000513 BinaryOperator::CreateAdd(Sub->getOperand(0), NegVal, "", Sub);
Chris Lattner6934a042007-02-11 01:23:03 +0000514 New->takeName(Sub);
Chris Lattner08b43922005-05-07 04:08:02 +0000515
516 // Everyone now refers to the add instruction.
Dale Johannesenf4978e22009-03-19 17:22:53 +0000517 ValueRankMap.erase(Sub);
Chris Lattner08b43922005-05-07 04:08:02 +0000518 Sub->replaceAllUsesWith(New);
Devang Patel5367b232011-04-28 22:48:14 +0000519 New->setDebugLoc(Sub->getDebugLoc());
Chris Lattner08b43922005-05-07 04:08:02 +0000520 Sub->eraseFromParent();
Jeff Cohen00b168892005-07-27 06:12:32 +0000521
David Greenea1fa76c2010-01-05 01:27:24 +0000522 DEBUG(dbgs() << "Negated: " << *New << '\n');
Chris Lattner08b43922005-05-07 04:08:02 +0000523 return New;
Chris Lattnera36e6c82002-05-16 04:37:07 +0000524}
525
Chris Lattner0975ed52005-05-07 04:24:13 +0000526/// ConvertShiftToMul - If this is a shift of a reassociable multiply or is used
527/// by one, change this into a multiply by a constant to assist with further
528/// reassociation.
Dale Johannesenf4978e22009-03-19 17:22:53 +0000529static Instruction *ConvertShiftToMul(Instruction *Shl,
Chris Lattnerf55e7f52010-01-01 00:01:34 +0000530 DenseMap<AssertingVH<>, unsigned> &ValueRankMap) {
Chris Lattner22a66c42006-03-14 06:55:18 +0000531 // If an operand of this shift is a reassociable multiply, or if the shift
532 // is used by a reassociable multiply or add, turn into a multiply.
533 if (isReassociableOp(Shl->getOperand(0), Instruction::Mul) ||
534 (Shl->hasOneUse() &&
535 (isReassociableOp(Shl->use_back(), Instruction::Mul) ||
536 isReassociableOp(Shl->use_back(), Instruction::Add)))) {
Owen Andersoneed707b2009-07-24 23:12:02 +0000537 Constant *MulCst = ConstantInt::get(Shl->getType(), 1);
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000538 MulCst = ConstantExpr::getShl(MulCst, cast<Constant>(Shl->getOperand(1)));
Chris Lattner22a66c42006-03-14 06:55:18 +0000539
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000540 Instruction *Mul =
541 BinaryOperator::CreateMul(Shl->getOperand(0), MulCst, "", Shl);
Dale Johannesenf4978e22009-03-19 17:22:53 +0000542 ValueRankMap.erase(Shl);
Chris Lattner6934a042007-02-11 01:23:03 +0000543 Mul->takeName(Shl);
Chris Lattner22a66c42006-03-14 06:55:18 +0000544 Shl->replaceAllUsesWith(Mul);
Devang Patel5367b232011-04-28 22:48:14 +0000545 Mul->setDebugLoc(Shl->getDebugLoc());
Chris Lattner22a66c42006-03-14 06:55:18 +0000546 Shl->eraseFromParent();
547 return Mul;
548 }
549 return 0;
Chris Lattner0975ed52005-05-07 04:24:13 +0000550}
551
Chris Lattner109d34d2005-05-08 18:59:37 +0000552// Scan backwards and forwards among values with the same rank as element i to
Chris Lattner9506c932010-01-01 01:13:15 +0000553// see if X exists. If X does not exist, return i. This is useful when
554// scanning for 'x' when we see '-x' because they both get the same rank.
Chris Lattner9f7b7082009-12-31 18:40:32 +0000555static unsigned FindInOperandList(SmallVectorImpl<ValueEntry> &Ops, unsigned i,
Chris Lattner109d34d2005-05-08 18:59:37 +0000556 Value *X) {
557 unsigned XRank = Ops[i].Rank;
558 unsigned e = Ops.size();
559 for (unsigned j = i+1; j != e && Ops[j].Rank == XRank; ++j)
560 if (Ops[j].Op == X)
561 return j;
Chris Lattner9506c932010-01-01 01:13:15 +0000562 // Scan backwards.
Chris Lattner109d34d2005-05-08 18:59:37 +0000563 for (unsigned j = i-1; j != ~0U && Ops[j].Rank == XRank; --j)
564 if (Ops[j].Op == X)
565 return j;
566 return i;
567}
568
Chris Lattnere5022fe2006-03-04 09:31:13 +0000569/// EmitAddTreeOfValues - Emit a tree of add instructions, summing Ops together
570/// and returning the result. Insert the tree before I.
Chris Lattner8d93b252009-12-31 07:48:51 +0000571static Value *EmitAddTreeOfValues(Instruction *I, SmallVectorImpl<Value*> &Ops){
Chris Lattnere5022fe2006-03-04 09:31:13 +0000572 if (Ops.size() == 1) return Ops.back();
573
574 Value *V1 = Ops.back();
575 Ops.pop_back();
576 Value *V2 = EmitAddTreeOfValues(I, Ops);
Gabor Greif7cbd8a32008-05-16 19:29:10 +0000577 return BinaryOperator::CreateAdd(V2, V1, "tmp", I);
Chris Lattnere5022fe2006-03-04 09:31:13 +0000578}
579
580/// RemoveFactorFromExpression - If V is an expression tree that is a
581/// multiplication sequence, and if this sequence contains a multiply by Factor,
582/// remove Factor from the tree and return the new tree.
583Value *Reassociate::RemoveFactorFromExpression(Value *V, Value *Factor) {
584 BinaryOperator *BO = isReassociableOp(V, Instruction::Mul);
585 if (!BO) return 0;
586
Chris Lattner9f7b7082009-12-31 18:40:32 +0000587 SmallVector<ValueEntry, 8> Factors;
Chris Lattnere5022fe2006-03-04 09:31:13 +0000588 LinearizeExprTree(BO, Factors);
589
590 bool FoundFactor = false;
Chris Lattner9506c932010-01-01 01:13:15 +0000591 bool NeedsNegate = false;
592 for (unsigned i = 0, e = Factors.size(); i != e; ++i) {
Chris Lattnere5022fe2006-03-04 09:31:13 +0000593 if (Factors[i].Op == Factor) {
594 FoundFactor = true;
595 Factors.erase(Factors.begin()+i);
596 break;
597 }
Chris Lattner9506c932010-01-01 01:13:15 +0000598
599 // If this is a negative version of this factor, remove it.
600 if (ConstantInt *FC1 = dyn_cast<ConstantInt>(Factor))
601 if (ConstantInt *FC2 = dyn_cast<ConstantInt>(Factors[i].Op))
602 if (FC1->getValue() == -FC2->getValue()) {
603 FoundFactor = NeedsNegate = true;
604 Factors.erase(Factors.begin()+i);
605 break;
606 }
607 }
608
Chris Lattnere9efecb2006-03-14 16:04:29 +0000609 if (!FoundFactor) {
610 // Make sure to restore the operands to the expression tree.
611 RewriteExprTree(BO, Factors);
612 return 0;
613 }
Chris Lattnere5022fe2006-03-04 09:31:13 +0000614
Chris Lattner9506c932010-01-01 01:13:15 +0000615 BasicBlock::iterator InsertPt = BO; ++InsertPt;
616
Chris Lattner1e7558b2009-12-31 19:34:45 +0000617 // If this was just a single multiply, remove the multiply and return the only
618 // remaining operand.
619 if (Factors.size() == 1) {
620 ValueRankMap.erase(BO);
Dan Gohmanfa0e6fa2011-03-10 19:51:54 +0000621 DeadInsts.push_back(BO);
Chris Lattner9506c932010-01-01 01:13:15 +0000622 V = Factors[0].Op;
623 } else {
624 RewriteExprTree(BO, Factors);
625 V = BO;
Chris Lattner1e7558b2009-12-31 19:34:45 +0000626 }
Chris Lattnere5022fe2006-03-04 09:31:13 +0000627
Chris Lattner9506c932010-01-01 01:13:15 +0000628 if (NeedsNegate)
629 V = BinaryOperator::CreateNeg(V, "neg", InsertPt);
630
631 return V;
Chris Lattnere5022fe2006-03-04 09:31:13 +0000632}
633
Chris Lattnere9efecb2006-03-14 16:04:29 +0000634/// FindSingleUseMultiplyFactors - If V is a single-use multiply, recursively
635/// add its operands as factors, otherwise add V to the list of factors.
Chris Lattner893075f2010-03-05 07:18:54 +0000636///
637/// Ops is the top-level list of add operands we're trying to factor.
Chris Lattnere9efecb2006-03-14 16:04:29 +0000638static void FindSingleUseMultiplyFactors(Value *V,
Chris Lattner893075f2010-03-05 07:18:54 +0000639 SmallVectorImpl<Value*> &Factors,
640 const SmallVectorImpl<ValueEntry> &Ops,
641 bool IsRoot) {
Chris Lattnere9efecb2006-03-14 16:04:29 +0000642 BinaryOperator *BO;
Chris Lattner893075f2010-03-05 07:18:54 +0000643 if (!(V->hasOneUse() || V->use_empty()) || // More than one use.
Chris Lattnere9efecb2006-03-14 16:04:29 +0000644 !(BO = dyn_cast<BinaryOperator>(V)) ||
645 BO->getOpcode() != Instruction::Mul) {
646 Factors.push_back(V);
647 return;
648 }
649
Chris Lattner893075f2010-03-05 07:18:54 +0000650 // If this value has a single use because it is another input to the add
651 // tree we're reassociating and we dropped its use, it actually has two
652 // uses and we can't factor it.
653 if (!IsRoot) {
654 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
655 if (Ops[i].Op == V) {
656 Factors.push_back(V);
657 return;
658 }
659 }
660
661
Chris Lattnere9efecb2006-03-14 16:04:29 +0000662 // Otherwise, add the LHS and RHS to the list of factors.
Chris Lattner893075f2010-03-05 07:18:54 +0000663 FindSingleUseMultiplyFactors(BO->getOperand(1), Factors, Ops, false);
664 FindSingleUseMultiplyFactors(BO->getOperand(0), Factors, Ops, false);
Chris Lattnere9efecb2006-03-14 16:04:29 +0000665}
666
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000667/// OptimizeAndOrXor - Optimize a series of operands to an 'and', 'or', or 'xor'
668/// instruction. This optimizes based on identities. If it can be reduced to
669/// a single Value, it is returned, otherwise the Ops list is mutated as
670/// necessary.
Chris Lattner9f7b7082009-12-31 18:40:32 +0000671static Value *OptimizeAndOrXor(unsigned Opcode,
672 SmallVectorImpl<ValueEntry> &Ops) {
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000673 // Scan the operand lists looking for X and ~X pairs, along with X,X pairs.
674 // If we find any, we can simplify the expression. X&~X == 0, X|~X == -1.
675 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
676 // First, check for X and ~X in the operand list.
677 assert(i < Ops.size());
678 if (BinaryOperator::isNot(Ops[i].Op)) { // Cannot occur for ^.
679 Value *X = BinaryOperator::getNotArgument(Ops[i].Op);
680 unsigned FoundX = FindInOperandList(Ops, i, X);
681 if (FoundX != i) {
Chris Lattner9fdaefa2009-12-31 17:51:05 +0000682 if (Opcode == Instruction::And) // ...&X&~X = 0
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000683 return Constant::getNullValue(X->getType());
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000684
Chris Lattner9fdaefa2009-12-31 17:51:05 +0000685 if (Opcode == Instruction::Or) // ...|X|~X = -1
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000686 return Constant::getAllOnesValue(X->getType());
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000687 }
688 }
689
690 // Next, check for duplicate pairs of values, which we assume are next to
691 // each other, due to our sorting criteria.
692 assert(i < Ops.size());
693 if (i+1 != Ops.size() && Ops[i+1].Op == Ops[i].Op) {
694 if (Opcode == Instruction::And || Opcode == Instruction::Or) {
Chris Lattnerf31e2e92009-12-31 19:49:01 +0000695 // Drop duplicate values for And and Or.
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000696 Ops.erase(Ops.begin()+i);
697 --i; --e;
698 ++NumAnnihil;
Chris Lattnerf31e2e92009-12-31 19:49:01 +0000699 continue;
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000700 }
Chris Lattnerf31e2e92009-12-31 19:49:01 +0000701
702 // Drop pairs of values for Xor.
703 assert(Opcode == Instruction::Xor);
704 if (e == 2)
705 return Constant::getNullValue(Ops[0].Op->getType());
706
Chris Lattner90461932010-01-01 00:04:26 +0000707 // Y ^ X^X -> Y
Chris Lattnerf31e2e92009-12-31 19:49:01 +0000708 Ops.erase(Ops.begin()+i, Ops.begin()+i+2);
709 i -= 1; e -= 2;
710 ++NumAnnihil;
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000711 }
712 }
713 return 0;
714}
Chris Lattnere9efecb2006-03-14 16:04:29 +0000715
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000716/// OptimizeAdd - Optimize a series of operands to an 'add' instruction. This
717/// optimizes based on identities. If it can be reduced to a single Value, it
718/// is returned, otherwise the Ops list is mutated as necessary.
Chris Lattner9f7b7082009-12-31 18:40:32 +0000719Value *Reassociate::OptimizeAdd(Instruction *I,
720 SmallVectorImpl<ValueEntry> &Ops) {
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000721 // Scan the operand lists looking for X and -X pairs. If we find any, we
Chris Lattner69e98e22009-12-31 19:24:52 +0000722 // can simplify the expression. X+-X == 0. While we're at it, scan for any
723 // duplicates. We want to canonicalize Y+Y+Y+Z -> 3*Y+Z.
Chris Lattner9506c932010-01-01 01:13:15 +0000724 //
725 // TODO: We could handle "X + ~X" -> "-1" if we wanted, since "-X = ~X+1".
726 //
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000727 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
Chris Lattner69e98e22009-12-31 19:24:52 +0000728 Value *TheOp = Ops[i].Op;
729 // Check to see if we've seen this operand before. If so, we factor all
Chris Lattnerf31e2e92009-12-31 19:49:01 +0000730 // instances of the operand together. Due to our sorting criteria, we know
731 // that these need to be next to each other in the vector.
732 if (i+1 != Ops.size() && Ops[i+1].Op == TheOp) {
733 // Rescan the list, remove all instances of this operand from the expr.
Chris Lattner69e98e22009-12-31 19:24:52 +0000734 unsigned NumFound = 0;
Chris Lattnerf31e2e92009-12-31 19:49:01 +0000735 do {
736 Ops.erase(Ops.begin()+i);
Chris Lattner69e98e22009-12-31 19:24:52 +0000737 ++NumFound;
Chris Lattnerf31e2e92009-12-31 19:49:01 +0000738 } while (i != Ops.size() && Ops[i].Op == TheOp);
739
Chris Lattnerf8a447d2009-12-31 19:25:19 +0000740 DEBUG(errs() << "\nFACTORING [" << NumFound << "]: " << *TheOp << '\n');
Chris Lattner69e98e22009-12-31 19:24:52 +0000741 ++NumFactor;
Chris Lattner69e98e22009-12-31 19:24:52 +0000742
743 // Insert a new multiply.
744 Value *Mul = ConstantInt::get(cast<IntegerType>(I->getType()), NumFound);
745 Mul = BinaryOperator::CreateMul(TheOp, Mul, "factor", I);
746
747 // Now that we have inserted a multiply, optimize it. This allows us to
748 // handle cases that require multiple factoring steps, such as this:
749 // (X*2) + (X*2) + (X*2) -> (X*2)*3 -> X*6
Dan Gohmandac5dba2011-04-12 00:11:56 +0000750 RedoInsts.push_back(Mul);
Chris Lattner69e98e22009-12-31 19:24:52 +0000751
752 // If every add operand was a duplicate, return the multiply.
753 if (Ops.empty())
754 return Mul;
755
756 // Otherwise, we had some input that didn't have the dupe, such as
757 // "A + A + B" -> "A*2 + B". Add the new multiply to the list of
758 // things being added by this operation.
759 Ops.insert(Ops.begin(), ValueEntry(getRank(Mul), Mul));
Chris Lattnerf31e2e92009-12-31 19:49:01 +0000760
761 --i;
762 e = Ops.size();
763 continue;
Chris Lattner69e98e22009-12-31 19:24:52 +0000764 }
765
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000766 // Check for X and -X in the operand list.
Chris Lattner69e98e22009-12-31 19:24:52 +0000767 if (!BinaryOperator::isNeg(TheOp))
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000768 continue;
769
Chris Lattner69e98e22009-12-31 19:24:52 +0000770 Value *X = BinaryOperator::getNegArgument(TheOp);
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000771 unsigned FoundX = FindInOperandList(Ops, i, X);
772 if (FoundX == i)
773 continue;
774
775 // Remove X and -X from the operand list.
Chris Lattner9fdaefa2009-12-31 17:51:05 +0000776 if (Ops.size() == 2)
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000777 return Constant::getNullValue(X->getType());
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000778
779 Ops.erase(Ops.begin()+i);
780 if (i < FoundX)
781 --FoundX;
782 else
783 --i; // Need to back up an extra one.
784 Ops.erase(Ops.begin()+FoundX);
785 ++NumAnnihil;
786 --i; // Revisit element.
787 e -= 2; // Removed two elements.
788 }
Chris Lattner94285e62009-12-31 18:17:13 +0000789
790 // Scan the operand list, checking to see if there are any common factors
791 // between operands. Consider something like A*A+A*B*C+D. We would like to
792 // reassociate this to A*(A+B*C)+D, which reduces the number of multiplies.
793 // To efficiently find this, we count the number of times a factor occurs
794 // for any ADD operands that are MULs.
795 DenseMap<Value*, unsigned> FactorOccurrences;
796
797 // Keep track of each multiply we see, to avoid triggering on (X*4)+(X*4)
798 // where they are actually the same multiply.
Chris Lattner94285e62009-12-31 18:17:13 +0000799 unsigned MaxOcc = 0;
800 Value *MaxOccVal = 0;
801 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
802 BinaryOperator *BOp = dyn_cast<BinaryOperator>(Ops[i].Op);
803 if (BOp == 0 || BOp->getOpcode() != Instruction::Mul || !BOp->use_empty())
804 continue;
805
Chris Lattner94285e62009-12-31 18:17:13 +0000806 // Compute all of the factors of this added value.
807 SmallVector<Value*, 8> Factors;
Chris Lattner893075f2010-03-05 07:18:54 +0000808 FindSingleUseMultiplyFactors(BOp, Factors, Ops, true);
Chris Lattner94285e62009-12-31 18:17:13 +0000809 assert(Factors.size() > 1 && "Bad linearize!");
810
811 // Add one to FactorOccurrences for each unique factor in this op.
Chris Lattner9506c932010-01-01 01:13:15 +0000812 SmallPtrSet<Value*, 8> Duplicates;
813 for (unsigned i = 0, e = Factors.size(); i != e; ++i) {
814 Value *Factor = Factors[i];
815 if (!Duplicates.insert(Factor)) continue;
816
817 unsigned Occ = ++FactorOccurrences[Factor];
818 if (Occ > MaxOcc) { MaxOcc = Occ; MaxOccVal = Factor; }
819
820 // If Factor is a negative constant, add the negated value as a factor
821 // because we can percolate the negate out. Watch for minint, which
822 // cannot be positivified.
823 if (ConstantInt *CI = dyn_cast<ConstantInt>(Factor))
Chris Lattnerc73b24d2011-07-15 06:08:15 +0000824 if (CI->isNegative() && !CI->isMinValue(true)) {
Chris Lattner9506c932010-01-01 01:13:15 +0000825 Factor = ConstantInt::get(CI->getContext(), -CI->getValue());
826 assert(!Duplicates.count(Factor) &&
827 "Shouldn't have two constant factors, missed a canonicalize");
828
829 unsigned Occ = ++FactorOccurrences[Factor];
830 if (Occ > MaxOcc) { MaxOcc = Occ; MaxOccVal = Factor; }
831 }
Chris Lattner94285e62009-12-31 18:17:13 +0000832 }
833 }
834
835 // If any factor occurred more than one time, we can pull it out.
836 if (MaxOcc > 1) {
Chris Lattner69e98e22009-12-31 19:24:52 +0000837 DEBUG(errs() << "\nFACTORING [" << MaxOcc << "]: " << *MaxOccVal << '\n');
Chris Lattner94285e62009-12-31 18:17:13 +0000838 ++NumFactor;
839
840 // Create a new instruction that uses the MaxOccVal twice. If we don't do
841 // this, we could otherwise run into situations where removing a factor
842 // from an expression will drop a use of maxocc, and this can cause
843 // RemoveFactorFromExpression on successive values to behave differently.
844 Instruction *DummyInst = BinaryOperator::CreateAdd(MaxOccVal, MaxOccVal);
845 SmallVector<Value*, 4> NewMulOps;
Duncan Sands37f87c72011-01-26 10:08:38 +0000846 for (unsigned i = 0; i != Ops.size(); ++i) {
Chris Lattnerc2d1b692010-01-09 06:01:36 +0000847 // Only try to remove factors from expressions we're allowed to.
848 BinaryOperator *BOp = dyn_cast<BinaryOperator>(Ops[i].Op);
849 if (BOp == 0 || BOp->getOpcode() != Instruction::Mul || !BOp->use_empty())
850 continue;
851
Chris Lattner94285e62009-12-31 18:17:13 +0000852 if (Value *V = RemoveFactorFromExpression(Ops[i].Op, MaxOccVal)) {
Duncan Sands37f87c72011-01-26 10:08:38 +0000853 // The factorized operand may occur several times. Convert them all in
854 // one fell swoop.
855 for (unsigned j = Ops.size(); j != i;) {
856 --j;
857 if (Ops[j].Op == Ops[i].Op) {
858 NewMulOps.push_back(V);
859 Ops.erase(Ops.begin()+j);
860 }
861 }
862 --i;
Chris Lattner94285e62009-12-31 18:17:13 +0000863 }
864 }
865
866 // No need for extra uses anymore.
867 delete DummyInst;
Duncan Sands54a57042010-01-08 17:51:48 +0000868
Chris Lattner94285e62009-12-31 18:17:13 +0000869 unsigned NumAddedValues = NewMulOps.size();
870 Value *V = EmitAddTreeOfValues(I, NewMulOps);
Duncan Sands54a57042010-01-08 17:51:48 +0000871
Chris Lattner69e98e22009-12-31 19:24:52 +0000872 // Now that we have inserted the add tree, optimize it. This allows us to
873 // handle cases that require multiple factoring steps, such as this:
Chris Lattner94285e62009-12-31 18:17:13 +0000874 // A*A*B + A*A*C --> A*(A*B+A*C) --> A*(A*(B+C))
Chris Lattner9cd1bc42009-12-31 18:18:46 +0000875 assert(NumAddedValues > 1 && "Each occurrence should contribute a value");
Duncan Sands54a57042010-01-08 17:51:48 +0000876 (void)NumAddedValues;
Chris Lattner69e98e22009-12-31 19:24:52 +0000877 V = ReassociateExpression(cast<BinaryOperator>(V));
878
879 // Create the multiply.
880 Value *V2 = BinaryOperator::CreateMul(V, MaxOccVal, "tmp", I);
881
Chris Lattnerf31e2e92009-12-31 19:49:01 +0000882 // Rerun associate on the multiply in case the inner expression turned into
883 // a multiply. We want to make sure that we keep things in canonical form.
884 V2 = ReassociateExpression(cast<BinaryOperator>(V2));
Chris Lattner94285e62009-12-31 18:17:13 +0000885
886 // If every add operand included the factor (e.g. "A*B + A*C"), then the
887 // entire result expression is just the multiply "A*(B+C)".
888 if (Ops.empty())
889 return V2;
890
Chris Lattner9cd1bc42009-12-31 18:18:46 +0000891 // Otherwise, we had some input that didn't have the factor, such as
Chris Lattner94285e62009-12-31 18:17:13 +0000892 // "A*B + A*C + D" -> "A*(B+C) + D". Add the new multiply to the list of
Chris Lattner9cd1bc42009-12-31 18:18:46 +0000893 // things being added by this operation.
Chris Lattner94285e62009-12-31 18:17:13 +0000894 Ops.insert(Ops.begin(), ValueEntry(getRank(V2), V2));
895 }
896
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000897 return 0;
898}
Chris Lattnere5022fe2006-03-04 09:31:13 +0000899
900Value *Reassociate::OptimizeExpression(BinaryOperator *I,
Chris Lattner9f7b7082009-12-31 18:40:32 +0000901 SmallVectorImpl<ValueEntry> &Ops) {
Chris Lattner46900102005-05-08 00:19:31 +0000902 // Now that we have the linearized expression tree, try to optimize it.
903 // Start by folding any constants that we found.
Chris Lattner109d34d2005-05-08 18:59:37 +0000904 bool IterateOptimization = false;
Chris Lattnere5022fe2006-03-04 09:31:13 +0000905 if (Ops.size() == 1) return Ops[0].Op;
Chris Lattner46900102005-05-08 00:19:31 +0000906
Chris Lattnere5022fe2006-03-04 09:31:13 +0000907 unsigned Opcode = I->getOpcode();
908
Chris Lattner46900102005-05-08 00:19:31 +0000909 if (Constant *V1 = dyn_cast<Constant>(Ops[Ops.size()-2].Op))
910 if (Constant *V2 = dyn_cast<Constant>(Ops.back().Op)) {
911 Ops.pop_back();
Owen Andersonbaf3c402009-07-29 18:55:55 +0000912 Ops.back().Op = ConstantExpr::get(Opcode, V1, V2);
Chris Lattnere5022fe2006-03-04 09:31:13 +0000913 return OptimizeExpression(I, Ops);
Chris Lattner46900102005-05-08 00:19:31 +0000914 }
915
916 // Check for destructive annihilation due to a constant being used.
Zhou Sheng6b6b6ef2007-01-11 12:24:14 +0000917 if (ConstantInt *CstVal = dyn_cast<ConstantInt>(Ops.back().Op))
Chris Lattner46900102005-05-08 00:19:31 +0000918 switch (Opcode) {
919 default: break;
920 case Instruction::And:
Chris Lattner90461932010-01-01 00:04:26 +0000921 if (CstVal->isZero()) // X & 0 -> 0
Chris Lattnere5022fe2006-03-04 09:31:13 +0000922 return CstVal;
Chris Lattner90461932010-01-01 00:04:26 +0000923 if (CstVal->isAllOnesValue()) // X & -1 -> X
Chris Lattner8d93b252009-12-31 07:48:51 +0000924 Ops.pop_back();
Chris Lattner46900102005-05-08 00:19:31 +0000925 break;
926 case Instruction::Mul:
Chris Lattner90461932010-01-01 00:04:26 +0000927 if (CstVal->isZero()) { // X * 0 -> 0
Chris Lattner109d34d2005-05-08 18:59:37 +0000928 ++NumAnnihil;
Chris Lattnere5022fe2006-03-04 09:31:13 +0000929 return CstVal;
Chris Lattner46900102005-05-08 00:19:31 +0000930 }
Chris Lattner8d93b252009-12-31 07:48:51 +0000931
932 if (cast<ConstantInt>(CstVal)->isOne())
Chris Lattner90461932010-01-01 00:04:26 +0000933 Ops.pop_back(); // X * 1 -> X
Chris Lattner46900102005-05-08 00:19:31 +0000934 break;
935 case Instruction::Or:
Chris Lattner90461932010-01-01 00:04:26 +0000936 if (CstVal->isAllOnesValue()) // X | -1 -> -1
Chris Lattnere5022fe2006-03-04 09:31:13 +0000937 return CstVal;
Chris Lattner46900102005-05-08 00:19:31 +0000938 // FALLTHROUGH!
939 case Instruction::Add:
940 case Instruction::Xor:
Chris Lattner90461932010-01-01 00:04:26 +0000941 if (CstVal->isZero()) // X [|^+] 0 -> X
Chris Lattner46900102005-05-08 00:19:31 +0000942 Ops.pop_back();
943 break;
944 }
Chris Lattnere5022fe2006-03-04 09:31:13 +0000945 if (Ops.size() == 1) return Ops[0].Op;
Chris Lattner46900102005-05-08 00:19:31 +0000946
Chris Lattnerec531232009-12-31 07:33:14 +0000947 // Handle destructive annihilation due to identities between elements in the
Chris Lattner46900102005-05-08 00:19:31 +0000948 // argument list here.
Chris Lattner109d34d2005-05-08 18:59:37 +0000949 switch (Opcode) {
950 default: break;
951 case Instruction::And:
952 case Instruction::Or:
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000953 case Instruction::Xor: {
954 unsigned NumOps = Ops.size();
955 if (Value *Result = OptimizeAndOrXor(Opcode, Ops))
956 return Result;
957 IterateOptimization |= Ops.size() != NumOps;
Chris Lattner109d34d2005-05-08 18:59:37 +0000958 break;
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000959 }
Chris Lattner109d34d2005-05-08 18:59:37 +0000960
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000961 case Instruction::Add: {
962 unsigned NumOps = Ops.size();
Chris Lattner94285e62009-12-31 18:17:13 +0000963 if (Value *Result = OptimizeAdd(I, Ops))
Chris Lattnerf3f55a92009-12-31 07:59:34 +0000964 return Result;
965 IterateOptimization |= Ops.size() != NumOps;
966 }
Chris Lattnere5022fe2006-03-04 09:31:13 +0000967
Chris Lattner109d34d2005-05-08 18:59:37 +0000968 break;
969 //case Instruction::Mul:
970 }
971
Jeff Cohen00b168892005-07-27 06:12:32 +0000972 if (IterateOptimization)
Chris Lattnere5022fe2006-03-04 09:31:13 +0000973 return OptimizeExpression(I, Ops);
974 return 0;
Chris Lattner46900102005-05-08 00:19:31 +0000975}
976
Chris Lattnera36e6c82002-05-16 04:37:07 +0000977
Dan Gohmandac5dba2011-04-12 00:11:56 +0000978/// ReassociateInst - Inspect and reassociate the instruction at the
979/// given position, post-incrementing the position.
980void Reassociate::ReassociateInst(BasicBlock::iterator &BBI) {
981 Instruction *BI = BBI++;
982 if (BI->getOpcode() == Instruction::Shl &&
983 isa<ConstantInt>(BI->getOperand(1)))
984 if (Instruction *NI = ConvertShiftToMul(BI, ValueRankMap)) {
985 MadeChange = true;
986 BI = NI;
Chris Lattnerf33151a2005-05-08 21:28:52 +0000987 }
Chris Lattnere4b73042002-10-31 17:12:59 +0000988
Dan Gohmandac5dba2011-04-12 00:11:56 +0000989 // Reject cases where it is pointless to do this.
990 if (!isa<BinaryOperator>(BI) || BI->getType()->isFloatingPointTy() ||
991 BI->getType()->isVectorTy())
992 return; // Floating point ops are not associative.
Jeff Cohen00b168892005-07-27 06:12:32 +0000993
Dan Gohmandac5dba2011-04-12 00:11:56 +0000994 // Do not reassociate boolean (i1) expressions. We want to preserve the
995 // original order of evaluation for short-circuited comparisons that
996 // SimplifyCFG has folded to AND/OR expressions. If the expression
997 // is not further optimized, it is likely to be transformed back to a
998 // short-circuited form for code gen, and the source order may have been
999 // optimized for the most likely conditions.
1000 if (BI->getType()->isIntegerTy(1))
1001 return;
Chris Lattnera36e6c82002-05-16 04:37:07 +00001002
Dan Gohmandac5dba2011-04-12 00:11:56 +00001003 // If this is a subtract instruction which is not already in negate form,
1004 // see if we can convert it to X+-Y.
1005 if (BI->getOpcode() == Instruction::Sub) {
1006 if (ShouldBreakUpSubtract(BI)) {
1007 BI = BreakUpSubtract(BI, ValueRankMap);
1008 // Reset the BBI iterator in case BreakUpSubtract changed the
1009 // instruction it points to.
1010 BBI = BI;
1011 ++BBI;
1012 MadeChange = true;
1013 } else if (BinaryOperator::isNeg(BI)) {
1014 // Otherwise, this is a negation. See if the operand is a multiply tree
1015 // and if this is not an inner node of a multiply tree.
1016 if (isReassociableOp(BI->getOperand(1), Instruction::Mul) &&
1017 (!BI->hasOneUse() ||
1018 !isReassociableOp(BI->use_back(), Instruction::Mul))) {
1019 BI = LowerNegateToMultiply(BI, ValueRankMap);
1020 MadeChange = true;
1021 }
1022 }
Chris Lattner895b3922006-03-14 07:11:11 +00001023 }
Dan Gohmandac5dba2011-04-12 00:11:56 +00001024
1025 // If this instruction is a commutative binary operator, process it.
1026 if (!BI->isAssociative()) return;
1027 BinaryOperator *I = cast<BinaryOperator>(BI);
1028
1029 // If this is an interior node of a reassociable tree, ignore it until we
1030 // get to the root of the tree, to avoid N^2 analysis.
1031 if (I->hasOneUse() && isReassociableOp(I->use_back(), I->getOpcode()))
1032 return;
1033
1034 // If this is an add tree that is used by a sub instruction, ignore it
1035 // until we process the subtract.
1036 if (I->hasOneUse() && I->getOpcode() == Instruction::Add &&
1037 cast<Instruction>(I->use_back())->getOpcode() == Instruction::Sub)
1038 return;
1039
1040 ReassociateExpression(I);
Chris Lattner895b3922006-03-14 07:11:11 +00001041}
Chris Lattnerc0649ac2005-05-07 21:59:39 +00001042
Chris Lattner69e98e22009-12-31 19:24:52 +00001043Value *Reassociate::ReassociateExpression(BinaryOperator *I) {
Chris Lattner895b3922006-03-14 07:11:11 +00001044
Chris Lattner69e98e22009-12-31 19:24:52 +00001045 // First, walk the expression tree, linearizing the tree, collecting the
1046 // operand information.
Chris Lattner9f7b7082009-12-31 18:40:32 +00001047 SmallVector<ValueEntry, 8> Ops;
Chris Lattner895b3922006-03-14 07:11:11 +00001048 LinearizeExprTree(I, Ops);
1049
David Greenea1fa76c2010-01-05 01:27:24 +00001050 DEBUG(dbgs() << "RAIn:\t"; PrintOps(I, Ops); dbgs() << '\n');
Chris Lattner895b3922006-03-14 07:11:11 +00001051
1052 // Now that we have linearized the tree to a list and have gathered all of
1053 // the operands and their ranks, sort the operands by their rank. Use a
1054 // stable_sort so that values with equal ranks will have their relative
1055 // positions maintained (and so the compiler is deterministic). Note that
1056 // this sorts so that the highest ranking values end up at the beginning of
1057 // the vector.
1058 std::stable_sort(Ops.begin(), Ops.end());
1059
1060 // OptimizeExpression - Now that we have the expression tree in a convenient
1061 // sorted form, optimize it globally if possible.
1062 if (Value *V = OptimizeExpression(I, Ops)) {
1063 // This expression tree simplified to something that isn't a tree,
1064 // eliminate it.
David Greenea1fa76c2010-01-05 01:27:24 +00001065 DEBUG(dbgs() << "Reassoc to scalar: " << *V << '\n');
Chris Lattner895b3922006-03-14 07:11:11 +00001066 I->replaceAllUsesWith(V);
Devang Patel5367b232011-04-28 22:48:14 +00001067 if (Instruction *VI = dyn_cast<Instruction>(V))
1068 VI->setDebugLoc(I->getDebugLoc());
Chris Lattner895b3922006-03-14 07:11:11 +00001069 RemoveDeadBinaryOp(I);
Chris Lattner9fdaefa2009-12-31 17:51:05 +00001070 ++NumAnnihil;
Chris Lattner69e98e22009-12-31 19:24:52 +00001071 return V;
Chris Lattner895b3922006-03-14 07:11:11 +00001072 }
1073
1074 // We want to sink immediates as deeply as possible except in the case where
1075 // this is a multiply tree used only by an add, and the immediate is a -1.
1076 // In this case we reassociate to put the negation on the outside so that we
1077 // can fold the negation into the add: (-X)*Y + Z -> Z-X*Y
1078 if (I->getOpcode() == Instruction::Mul && I->hasOneUse() &&
1079 cast<Instruction>(I->use_back())->getOpcode() == Instruction::Add &&
1080 isa<ConstantInt>(Ops.back().Op) &&
1081 cast<ConstantInt>(Ops.back().Op)->isAllOnesValue()) {
Chris Lattner9f7b7082009-12-31 18:40:32 +00001082 ValueEntry Tmp = Ops.pop_back_val();
1083 Ops.insert(Ops.begin(), Tmp);
Chris Lattner895b3922006-03-14 07:11:11 +00001084 }
1085
David Greenea1fa76c2010-01-05 01:27:24 +00001086 DEBUG(dbgs() << "RAOut:\t"; PrintOps(I, Ops); dbgs() << '\n');
Chris Lattner895b3922006-03-14 07:11:11 +00001087
1088 if (Ops.size() == 1) {
1089 // This expression tree simplified to something that isn't a tree,
1090 // eliminate it.
1091 I->replaceAllUsesWith(Ops[0].Op);
Devang Patel5367b232011-04-28 22:48:14 +00001092 if (Instruction *OI = dyn_cast<Instruction>(Ops[0].Op))
1093 OI->setDebugLoc(I->getDebugLoc());
Chris Lattner895b3922006-03-14 07:11:11 +00001094 RemoveDeadBinaryOp(I);
Chris Lattner69e98e22009-12-31 19:24:52 +00001095 return Ops[0].Op;
Chris Lattner4fd56002002-05-08 22:19:27 +00001096 }
Chris Lattner69e98e22009-12-31 19:24:52 +00001097
1098 // Now that we ordered and optimized the expressions, splat them back into
1099 // the expression tree, removing any unneeded nodes.
1100 RewriteExprTree(I, Ops);
1101 return I;
Chris Lattner4fd56002002-05-08 22:19:27 +00001102}
1103
1104
Chris Lattner7e708292002-06-25 16:13:24 +00001105bool Reassociate::runOnFunction(Function &F) {
Devang Patel16195602011-07-29 19:00:35 +00001106 collectDbgValues(F);
Chris Lattner4fd56002002-05-08 22:19:27 +00001107 // Recalculate the rank map for F
1108 BuildRankMap(F);
1109
Chris Lattnerc0649ac2005-05-07 21:59:39 +00001110 MadeChange = false;
Chris Lattner7e708292002-06-25 16:13:24 +00001111 for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
Dan Gohmandac5dba2011-04-12 00:11:56 +00001112 for (BasicBlock::iterator BBI = FI->begin(); BBI != FI->end(); )
1113 ReassociateInst(BBI);
1114
1115 // Now that we're done, revisit any instructions which are likely to
1116 // have secondary reassociation opportunities.
1117 while (!RedoInsts.empty())
1118 if (Value *V = RedoInsts.pop_back_val()) {
1119 BasicBlock::iterator BBI = cast<Instruction>(V);
1120 ReassociateInst(BBI);
1121 }
Chris Lattner4fd56002002-05-08 22:19:27 +00001122
Dan Gohmanfa0e6fa2011-03-10 19:51:54 +00001123 // Now that we're done, delete any instructions which are no longer used.
1124 while (!DeadInsts.empty())
Dan Gohmanc9f2f612011-03-10 20:57:44 +00001125 if (Value *V = DeadInsts.pop_back_val())
Devang Patel16195602011-07-29 19:00:35 +00001126 if (!RecursivelyDeleteTriviallyDeadInstructions(V))
1127 if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(V))
1128 DVI->eraseFromParent();
Dan Gohmanfa0e6fa2011-03-10 19:51:54 +00001129
Chris Lattnerf55e7f52010-01-01 00:01:34 +00001130 // We are done with the rank map.
Chris Lattner4fd56002002-05-08 22:19:27 +00001131 RankMap.clear();
Chris Lattnerfb5be092003-08-13 16:16:26 +00001132 ValueRankMap.clear();
Devang Patel6e8bb8a2011-07-29 19:49:58 +00001133 DbgValues.clear();
Chris Lattnerc0649ac2005-05-07 21:59:39 +00001134 return MadeChange;
Chris Lattner4fd56002002-05-08 22:19:27 +00001135}
Brian Gaeked0fde302003-11-11 22:41:34 +00001136
Devang Patel16195602011-07-29 19:00:35 +00001137/// collectDbgValues - Collect all llvm.dbg.value intrinsics.
1138void Reassociate::collectDbgValues(Function &F) {
1139 for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
1140 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1141 BI != BE; ++BI)
1142 if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(BI))
1143 DbgValues[DVI->getValue()] = DVI;
1144}