14b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick//===-- SimplifyIndVar.cpp - Induction variable simplification ------------===// 24b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick// 34b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick// The LLVM Compiler Infrastructure 44b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick// 54b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick// This file is distributed under the University of Illinois Open Source 64b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick// License. See LICENSE.TXT for details. 74b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick// 84b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick//===----------------------------------------------------------------------===// 94b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick// 104b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick// This file implements induction variable simplification. It does 114b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick// not define any actual pass or policy, but provides a single function to 124b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick// simplify a loop's induction variables based on ScalarEvolution. 134b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick// 144b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick//===----------------------------------------------------------------------===// 154b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 16d04a8d4b33ff316ca4cf961e06c9e312eff8e64fChandler Carruth#include "llvm/Transforms/Utils/SimplifyIndVar.h" 1736b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines#include "llvm/ADT/STLExtras.h" 18d04a8d4b33ff316ca4cf961e06c9e312eff8e64fChandler Carruth#include "llvm/ADT/SmallVector.h" 19d04a8d4b33ff316ca4cf961e06c9e312eff8e64fChandler Carruth#include "llvm/ADT/Statistic.h" 204b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick#include "llvm/Analysis/IVUsers.h" 214b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick#include "llvm/Analysis/LoopInfo.h" 224b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick#include "llvm/Analysis/LoopPass.h" 234b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick#include "llvm/Analysis/ScalarEvolutionExpressions.h" 240b8c9a80f20772c3793201ab5b251d3520b9cea3Chandler Carruth#include "llvm/IR/DataLayout.h" 2536b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines#include "llvm/IR/Dominators.h" 2636b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines#include "llvm/IR/IRBuilder.h" 270b8c9a80f20772c3793201ab5b251d3520b9cea3Chandler Carruth#include "llvm/IR/Instructions.h" 2836b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines#include "llvm/IR/IntrinsicInst.h" 294b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick#include "llvm/Support/CommandLine.h" 304b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick#include "llvm/Support/Debug.h" 314b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick#include "llvm/Support/raw_ostream.h" 324b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 334b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trickusing namespace llvm; 344b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 35dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines#define DEBUG_TYPE "indvars" 36dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines 374b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew TrickSTATISTIC(NumElimIdentity, "Number of IV identities eliminated"); 384b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew TrickSTATISTIC(NumElimOperand, "Number of IV operands folded into a use"); 394b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew TrickSTATISTIC(NumElimRem , "Number of IV remainder operations eliminated"); 404b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew TrickSTATISTIC(NumElimCmp , "Number of IV comparisons eliminated"); 414b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 424b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Tricknamespace { 434b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick /// SimplifyIndvar - This is a utility for simplifying induction variables 444b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick /// based on ScalarEvolution. It is the primary instrument of the 454b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick /// IndvarSimplify pass, but it may also be directly invoked to cleanup after 464b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick /// other loop passes that preserve SCEV. 474b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick class SimplifyIndvar { 484b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick Loop *L; 494b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick LoopInfo *LI; 504b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick ScalarEvolution *SE; 5136b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines const DataLayout *DL; // May be NULL 524b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 534b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick SmallVectorImpl<WeakVH> &DeadInsts; 544b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 554b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick bool Changed; 564b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 574b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick public: 58bddb7f82103deb226baa6793f41c5961661167e7Andrew Trick SimplifyIndvar(Loop *Loop, ScalarEvolution *SE, LPPassManager *LPM, 59dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines SmallVectorImpl<WeakVH> &Dead, IVUsers *IVU = nullptr) : 604b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick L(Loop), 614b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick LI(LPM->getAnalysisIfAvailable<LoopInfo>()), 62bddb7f82103deb226baa6793f41c5961661167e7Andrew Trick SE(SE), 634b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick DeadInsts(Dead), 644b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick Changed(false) { 6536b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines DataLayoutPass *DLP = LPM->getAnalysisIfAvailable<DataLayoutPass>(); 66dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines DL = DLP ? &DLP->getDataLayout() : nullptr; 67bddb7f82103deb226baa6793f41c5961661167e7Andrew Trick assert(LI && "IV simplification requires LoopInfo"); 684b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick } 694b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 704b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick bool hasChanged() const { return Changed; } 714b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 724b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick /// Iteratively perform simplification on a worklist of users of the 734b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick /// specified induction variable. This is the top-level driver that applies 744b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick /// all simplicitions to users of an IV. 75dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines void simplifyUsers(PHINode *CurrIV, IVVisitor *V = nullptr); 764b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 77ea23daa4461de489abbfd54a9641091862945f3eAndrew Trick Value *foldIVUser(Instruction *UseInst, Instruction *IVOperand); 784b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 794b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick bool eliminateIVUser(Instruction *UseInst, Instruction *IVOperand); 804b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick void eliminateIVComparison(ICmpInst *ICmp, Value *IVOperand); 814b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick void eliminateIVRemainder(BinaryOperator *Rem, Value *IVOperand, 824b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick bool IsSigned); 8336b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines 8436b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines Instruction *splitOverflowIntrinsic(Instruction *IVUser, 8536b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines const DominatorTree *DT); 864b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick }; 874b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick} 884b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 894b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// foldIVUser - Fold an IV operand into its use. This removes increments of an 904b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// aligned IV when used by a instruction that ignores the low bits. 91ea23daa4461de489abbfd54a9641091862945f3eAndrew Trick/// 9224f48ece526d81e7a3138f4cff57171b7de9e02fAndrew Trick/// IVOperand is guaranteed SCEVable, but UseInst may not be. 9324f48ece526d81e7a3138f4cff57171b7de9e02fAndrew Trick/// 94ea23daa4461de489abbfd54a9641091862945f3eAndrew Trick/// Return the operand of IVOperand for this induction variable if IVOperand can 957cb3dcb927a8f8a872cdf309f78cd80e197d2f14Andrew Trick/// be folded (in case more folding opportunities have been exposed). 96ea23daa4461de489abbfd54a9641091862945f3eAndrew Trick/// Otherwise return null. 97ea23daa4461de489abbfd54a9641091862945f3eAndrew TrickValue *SimplifyIndvar::foldIVUser(Instruction *UseInst, Instruction *IVOperand) { 98dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines Value *IVSrc = nullptr; 994b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick unsigned OperIdx = 0; 100dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines const SCEV *FoldedExpr = nullptr; 1014b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick switch (UseInst->getOpcode()) { 1024b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick default: 103dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines return nullptr; 1044b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick case Instruction::UDiv: 1054b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick case Instruction::LShr: 1064b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // We're only interested in the case where we know something about 1074b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // the numerator and have a constant denominator. 1084b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (IVOperand != UseInst->getOperand(OperIdx) || 1094b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick !isa<ConstantInt>(UseInst->getOperand(1))) 110dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines return nullptr; 1114b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 1124b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // Attempt to fold a binary operator with constant operand. 1134b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // e.g. ((I + 1) >> 2) => I >> 2 1144f3052403ca5ea9542a118c2e54ff9c82038f41cAndrew Trick if (!isa<BinaryOperator>(IVOperand) 1154f3052403ca5ea9542a118c2e54ff9c82038f41cAndrew Trick || !isa<ConstantInt>(IVOperand->getOperand(1))) 116dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines return nullptr; 1174b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 1184b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick IVSrc = IVOperand->getOperand(0); 1194b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // IVSrc must be the (SCEVable) IV, since the other operand is const. 1204b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick assert(SE->isSCEVable(IVSrc->getType()) && "Expect SCEVable IV operand"); 1214b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 1224b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick ConstantInt *D = cast<ConstantInt>(UseInst->getOperand(1)); 1234b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (UseInst->getOpcode() == Instruction::LShr) { 1244b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // Get a constant for the divisor. See createSCEV. 1254b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick uint32_t BitWidth = cast<IntegerType>(UseInst->getType())->getBitWidth(); 1264b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (D->getValue().uge(BitWidth)) 127dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines return nullptr; 1284b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 1294b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick D = ConstantInt::get(UseInst->getContext(), 1300a230e0d985625a3909cb78fd867a3abaf434565Benjamin Kramer APInt::getOneBitSet(BitWidth, D->getZExtValue())); 1314b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick } 1324b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick FoldedExpr = SE->getUDivExpr(SE->getSCEV(IVSrc), SE->getSCEV(D)); 1334b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick } 1344b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // We have something that might fold it's operand. Compare SCEVs. 1354b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (!SE->isSCEVable(UseInst->getType())) 136dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines return nullptr; 1374b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 1384b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // Bypass the operand if SCEV can prove it has no effect. 1394b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (SE->getSCEV(UseInst) != FoldedExpr) 140dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines return nullptr; 1414b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 1424b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick DEBUG(dbgs() << "INDVARS: Eliminated IV operand: " << *IVOperand 1434b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick << " -> " << *UseInst << '\n'); 1444b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 1454b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick UseInst->setOperand(OperIdx, IVSrc); 1464b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick assert(SE->getSCEV(UseInst) == FoldedExpr && "bad SCEV with folded oper"); 1474b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 1484b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick ++NumElimOperand; 1494b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick Changed = true; 1504b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (IVOperand->use_empty()) 1514b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick DeadInsts.push_back(IVOperand); 152ea23daa4461de489abbfd54a9641091862945f3eAndrew Trick return IVSrc; 1534b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick} 1544b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 1554b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// eliminateIVComparison - SimplifyIVUsers helper for eliminating useless 1564b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// comparisons against an induction variable. 1574b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trickvoid SimplifyIndvar::eliminateIVComparison(ICmpInst *ICmp, Value *IVOperand) { 1584b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick unsigned IVOperIdx = 0; 1594b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick ICmpInst::Predicate Pred = ICmp->getPredicate(); 1604b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (IVOperand != ICmp->getOperand(0)) { 1614b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // Swapped 1624b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick assert(IVOperand == ICmp->getOperand(1) && "Can't find IVOperand"); 1634b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick IVOperIdx = 1; 1644b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick Pred = ICmpInst::getSwappedPredicate(Pred); 1654b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick } 1664b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 1674b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // Get the SCEVs for the ICmp operands. 1684b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick const SCEV *S = SE->getSCEV(ICmp->getOperand(IVOperIdx)); 1694b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick const SCEV *X = SE->getSCEV(ICmp->getOperand(1 - IVOperIdx)); 1704b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 1714b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // Simplify unnecessary loops away. 1724b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick const Loop *ICmpLoop = LI->getLoopFor(ICmp->getParent()); 1734b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick S = SE->getSCEVAtScope(S, ICmpLoop); 1744b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick X = SE->getSCEVAtScope(X, ICmpLoop); 1754b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 1764b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // If the condition is always true or always false, replace it with 1774b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // a constant value. 1784b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (SE->isKnownPredicate(Pred, S, X)) 1794b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick ICmp->replaceAllUsesWith(ConstantInt::getTrue(ICmp->getContext())); 1804b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick else if (SE->isKnownPredicate(ICmpInst::getInversePredicate(Pred), S, X)) 1814b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick ICmp->replaceAllUsesWith(ConstantInt::getFalse(ICmp->getContext())); 1824b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick else 1834b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick return; 1844b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 1854b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick DEBUG(dbgs() << "INDVARS: Eliminated comparison: " << *ICmp << '\n'); 1864b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick ++NumElimCmp; 1874b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick Changed = true; 1884b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick DeadInsts.push_back(ICmp); 1894b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick} 1904b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 1914b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// eliminateIVRemainder - SimplifyIVUsers helper for eliminating useless 1924b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// remainder operations operating on an induction variable. 1934b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trickvoid SimplifyIndvar::eliminateIVRemainder(BinaryOperator *Rem, 1944b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick Value *IVOperand, 1954b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick bool IsSigned) { 1964b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // We're only interested in the case where we know something about 1974b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // the numerator. 1984b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (IVOperand != Rem->getOperand(0)) 1994b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick return; 2004b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 2014b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // Get the SCEVs for the ICmp operands. 2024b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick const SCEV *S = SE->getSCEV(Rem->getOperand(0)); 2034b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick const SCEV *X = SE->getSCEV(Rem->getOperand(1)); 2044b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 2054b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // Simplify unnecessary loops away. 2064b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick const Loop *ICmpLoop = LI->getLoopFor(Rem->getParent()); 2074b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick S = SE->getSCEVAtScope(S, ICmpLoop); 2084b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick X = SE->getSCEVAtScope(X, ICmpLoop); 2094b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 2104b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // i % n --> i if i is in [0,n). 2114b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if ((!IsSigned || SE->isKnownNonNegative(S)) && 2124b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick SE->isKnownPredicate(IsSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT, 2134b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick S, X)) 2144b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick Rem->replaceAllUsesWith(Rem->getOperand(0)); 2154b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick else { 2164b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // (i+1) % n --> (i+1)==n?0:(i+1) if i is in [0,n). 2174b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick const SCEV *LessOne = 2184b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick SE->getMinusSCEV(S, SE->getConstant(S->getType(), 1)); 2194b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (IsSigned && !SE->isKnownNonNegative(LessOne)) 2204b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick return; 2214b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 2224b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (!SE->isKnownPredicate(IsSigned ? 2234b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT, 2244b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick LessOne, X)) 2254b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick return; 2264b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 2274b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick ICmpInst *ICmp = new ICmpInst(Rem, ICmpInst::ICMP_EQ, 228a9390a4d5f5d568059a80970d22194b165d097a7Benjamin Kramer Rem->getOperand(0), Rem->getOperand(1)); 2294b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick SelectInst *Sel = 2304b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick SelectInst::Create(ICmp, 2314b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick ConstantInt::get(Rem->getType(), 0), 2324b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick Rem->getOperand(0), "tmp", Rem); 2334b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick Rem->replaceAllUsesWith(Sel); 2344b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick } 2354b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 2364b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick DEBUG(dbgs() << "INDVARS: Simplified rem: " << *Rem << '\n'); 2374b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick ++NumElimRem; 2384b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick Changed = true; 2394b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick DeadInsts.push_back(Rem); 2404b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick} 2414b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 2424b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// eliminateIVUser - Eliminate an operation that consumes a simple IV and has 2434b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// no observable side-effect given the range of IV values. 24424f48ece526d81e7a3138f4cff57171b7de9e02fAndrew Trick/// IVOperand is guaranteed SCEVable, but UseInst may not be. 2454b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trickbool SimplifyIndvar::eliminateIVUser(Instruction *UseInst, 2464b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick Instruction *IVOperand) { 2474b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (ICmpInst *ICmp = dyn_cast<ICmpInst>(UseInst)) { 2484b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick eliminateIVComparison(ICmp, IVOperand); 2494b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick return true; 2504b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick } 2514b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (BinaryOperator *Rem = dyn_cast<BinaryOperator>(UseInst)) { 2524b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick bool IsSigned = Rem->getOpcode() == Instruction::SRem; 2534b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (IsSigned || Rem->getOpcode() == Instruction::URem) { 2544b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick eliminateIVRemainder(Rem, IVOperand, IsSigned); 2554b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick return true; 2564b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick } 2574b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick } 2584b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 2594b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // Eliminate any operation that SCEV can prove is an identity function. 2604b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (!SE->isSCEVable(UseInst->getType()) || 2614b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick (UseInst->getType() != IVOperand->getType()) || 2624b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick (SE->getSCEV(UseInst) != SE->getSCEV(IVOperand))) 2634b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick return false; 2644b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 2654b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick DEBUG(dbgs() << "INDVARS: Eliminated identity: " << *UseInst << '\n'); 2664b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 2674b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick UseInst->replaceAllUsesWith(IVOperand); 2684b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick ++NumElimIdentity; 2694b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick Changed = true; 2704b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick DeadInsts.push_back(UseInst); 2714b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick return true; 2724b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick} 2734b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 27436b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines/// \brief Split sadd.with.overflow into add + sadd.with.overflow to allow 27536b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines/// analysis and optimization. 27636b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines/// 27736b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines/// \return A new value representing the non-overflowing add if possible, 27836b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines/// otherwise return the original value. 27936b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen HinesInstruction *SimplifyIndvar::splitOverflowIntrinsic(Instruction *IVUser, 28036b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines const DominatorTree *DT) { 28136b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines IntrinsicInst *II = dyn_cast<IntrinsicInst>(IVUser); 28236b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines if (!II || II->getIntrinsicID() != Intrinsic::sadd_with_overflow) 28336b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines return IVUser; 28436b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines 28536b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines // Find a branch guarded by the overflow check. 286dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines BranchInst *Branch = nullptr; 287dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines Instruction *AddVal = nullptr; 28836b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines for (User *U : II->users()) { 28936b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines if (ExtractValueInst *ExtractInst = dyn_cast<ExtractValueInst>(U)) { 29036b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines if (ExtractInst->getNumIndices() != 1) 29136b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines continue; 29236b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines if (ExtractInst->getIndices()[0] == 0) 29336b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines AddVal = ExtractInst; 29436b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines else if (ExtractInst->getIndices()[0] == 1 && ExtractInst->hasOneUse()) 29536b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines Branch = dyn_cast<BranchInst>(ExtractInst->user_back()); 29636b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines } 29736b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines } 29836b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines if (!AddVal || !Branch) 29936b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines return IVUser; 30036b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines 30136b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines BasicBlock *ContinueBB = Branch->getSuccessor(1); 30236b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines if (std::next(pred_begin(ContinueBB)) != pred_end(ContinueBB)) 30336b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines return IVUser; 30436b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines 30536b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines // Check if all users of the add are provably NSW. 30636b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines bool AllNSW = true; 30736b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines for (Use &U : AddVal->uses()) { 30836b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines if (Instruction *UseInst = dyn_cast<Instruction>(U.getUser())) { 30936b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines BasicBlock *UseBB = UseInst->getParent(); 31036b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines if (PHINode *PHI = dyn_cast<PHINode>(UseInst)) 31136b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines UseBB = PHI->getIncomingBlock(U); 31236b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines if (!DT->dominates(ContinueBB, UseBB)) { 31336b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines AllNSW = false; 31436b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines break; 31536b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines } 31636b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines } 31736b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines } 31836b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines if (!AllNSW) 31936b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines return IVUser; 32036b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines 32136b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines // Go for it... 32236b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines IRBuilder<> Builder(IVUser); 32336b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines Instruction *AddInst = dyn_cast<Instruction>( 32436b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines Builder.CreateNSWAdd(II->getOperand(0), II->getOperand(1))); 32536b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines 32636b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines // The caller expects the new add to have the same form as the intrinsic. The 32736b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines // IV operand position must be the same. 32836b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines assert((AddInst->getOpcode() == Instruction::Add && 32936b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines AddInst->getOperand(0) == II->getOperand(0)) && 33036b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines "Bad add instruction created from overflow intrinsic."); 33136b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines 33236b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines AddVal->replaceAllUsesWith(AddInst); 33336b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines DeadInsts.push_back(AddVal); 33436b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines return AddInst; 33536b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines} 33636b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines 3374b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// pushIVUsers - Add all uses of Def to the current IV's worklist. 3384b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// 3394b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trickstatic void pushIVUsers( 3404b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick Instruction *Def, 3414b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick SmallPtrSet<Instruction*,16> &Simplified, 3424b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick SmallVectorImpl< std::pair<Instruction*,Instruction*> > &SimpleIVUsers) { 3434b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 34436b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines for (User *U : Def->users()) { 34536b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines Instruction *UI = cast<Instruction>(U); 3464b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 3474b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // Avoid infinite or exponential worklist processing. 3484b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // Also ensure unique worklist users. 3494b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // If Def is a LoopPhi, it may not be in the Simplified set, so check for 3504b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // self edges first. 35136b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines if (UI != Def && Simplified.insert(UI)) 35236b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines SimpleIVUsers.push_back(std::make_pair(UI, Def)); 3534b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick } 3544b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick} 3554b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 3564b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// isSimpleIVUser - Return true if this instruction generates a simple SCEV 3574b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// expression in terms of that IV. 3584b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// 3597cb3dcb927a8f8a872cdf309f78cd80e197d2f14Andrew Trick/// This is similar to IVUsers' isInteresting() but processes each instruction 3604b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// non-recursively when the operand is already known to be a simpleIVUser. 3614b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// 3624b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trickstatic bool isSimpleIVUser(Instruction *I, const Loop *L, ScalarEvolution *SE) { 3634b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (!SE->isSCEVable(I->getType())) 3644b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick return false; 3654b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 3664b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // Get the symbolic expression for this instruction. 3674b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick const SCEV *S = SE->getSCEV(I); 3684b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 3694b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // Only consider affine recurrences. 3704b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S); 3714b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (AR && AR->getLoop() == L) 3724b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick return true; 3734b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 3744b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick return false; 3754b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick} 3764b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 3774b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// simplifyUsers - Iteratively perform simplification on a worklist of users 3784b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// of the specified induction variable. Each successive simplification may push 3794b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// more users which may themselves be candidates for simplification. 3804b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// 3814b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// This algorithm does not require IVUsers analysis. Instead, it simplifies 3824b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// instructions in-place during analysis. Rather than rewriting induction 3834b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// variables bottom-up from their users, it transforms a chain of IVUsers 3844b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// top-down, updating the IR only when it encouters a clear optimization 3854b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// opportunitiy. 3864b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// 3874b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// Once DisableIVRewrite is default, LSR will be the only client of IVUsers. 3884b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// 3894b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trickvoid SimplifyIndvar::simplifyUsers(PHINode *CurrIV, IVVisitor *V) { 39024f48ece526d81e7a3138f4cff57171b7de9e02fAndrew Trick if (!SE->isSCEVable(CurrIV->getType())) 39124f48ece526d81e7a3138f4cff57171b7de9e02fAndrew Trick return; 39224f48ece526d81e7a3138f4cff57171b7de9e02fAndrew Trick 3934b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // Instructions processed by SimplifyIndvar for CurrIV. 3944b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick SmallPtrSet<Instruction*,16> Simplified; 3954b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 3964b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // Use-def pairs if IV users waiting to be processed for CurrIV. 3974b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick SmallVector<std::pair<Instruction*, Instruction*>, 8> SimpleIVUsers; 3984b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 3994b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // Push users of the current LoopPhi. In rare cases, pushIVUsers may be 4004b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // called multiple times for the same LoopPhi. This is the proper thing to 4014b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // do for loop header phis that use each other. 4024b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick pushIVUsers(CurrIV, Simplified, SimpleIVUsers); 4034b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 4044b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick while (!SimpleIVUsers.empty()) { 4054b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick std::pair<Instruction*, Instruction*> UseOper = 4064b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick SimpleIVUsers.pop_back_val(); 40736b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines Instruction *UseInst = UseOper.first; 40836b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines 4094b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // Bypass back edges to avoid extra work. 41036b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines if (UseInst == CurrIV) continue; 41136b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines 41236b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines if (V && V->shouldSplitOverflowInstrinsics()) { 41336b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines UseInst = splitOverflowIntrinsic(UseInst, V->getDomTree()); 41436b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines if (!UseInst) 41536b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines continue; 41636b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines } 4174b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 418ea23daa4461de489abbfd54a9641091862945f3eAndrew Trick Instruction *IVOperand = UseOper.second; 419ea23daa4461de489abbfd54a9641091862945f3eAndrew Trick for (unsigned N = 0; IVOperand; ++N) { 420ea23daa4461de489abbfd54a9641091862945f3eAndrew Trick assert(N <= Simplified.size() && "runaway iteration"); 421ea23daa4461de489abbfd54a9641091862945f3eAndrew Trick 422ea23daa4461de489abbfd54a9641091862945f3eAndrew Trick Value *NewOper = foldIVUser(UseOper.first, IVOperand); 423ea23daa4461de489abbfd54a9641091862945f3eAndrew Trick if (!NewOper) 424ea23daa4461de489abbfd54a9641091862945f3eAndrew Trick break; // done folding 425ea23daa4461de489abbfd54a9641091862945f3eAndrew Trick IVOperand = dyn_cast<Instruction>(NewOper); 426ea23daa4461de489abbfd54a9641091862945f3eAndrew Trick } 427ea23daa4461de489abbfd54a9641091862945f3eAndrew Trick if (!IVOperand) 428ea23daa4461de489abbfd54a9641091862945f3eAndrew Trick continue; 4294b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 430ea23daa4461de489abbfd54a9641091862945f3eAndrew Trick if (eliminateIVUser(UseOper.first, IVOperand)) { 431ea23daa4461de489abbfd54a9641091862945f3eAndrew Trick pushIVUsers(IVOperand, Simplified, SimpleIVUsers); 4324b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick continue; 4334b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick } 4344b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick CastInst *Cast = dyn_cast<CastInst>(UseOper.first); 4354b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (V && Cast) { 4364b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick V->visitCast(Cast); 4374b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick continue; 4384b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick } 4394b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (isSimpleIVUser(UseOper.first, L, SE)) { 4404b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick pushIVUsers(UseOper.first, Simplified, SimpleIVUsers); 4414b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick } 4424b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick } 4434b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick} 4444b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 4454b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Tricknamespace llvm { 4464b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 4472d24e2a396a1d211baaeedf32148a3b657240170David Blaikievoid IVVisitor::anchor() { } 4482d24e2a396a1d211baaeedf32148a3b657240170David Blaikie 4494b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// simplifyUsersOfIV - Simplify instructions that use this induction variable 4504b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// by using ScalarEvolution to analyze the IV's recurrence. 451bddb7f82103deb226baa6793f41c5961661167e7Andrew Trickbool simplifyUsersOfIV(PHINode *CurrIV, ScalarEvolution *SE, LPPassManager *LPM, 4524b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick SmallVectorImpl<WeakVH> &Dead, IVVisitor *V) 4534b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick{ 4544b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick LoopInfo *LI = &LPM->getAnalysis<LoopInfo>(); 455bddb7f82103deb226baa6793f41c5961661167e7Andrew Trick SimplifyIndvar SIV(LI->getLoopFor(CurrIV->getParent()), SE, LPM, Dead); 4564b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick SIV.simplifyUsers(CurrIV, V); 4574b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick return SIV.hasChanged(); 4584b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick} 4594b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 4604b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// simplifyLoopIVs - Simplify users of induction variables within this 4614b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// loop. This does not actually change or add IVs. 462bddb7f82103deb226baa6793f41c5961661167e7Andrew Trickbool simplifyLoopIVs(Loop *L, ScalarEvolution *SE, LPPassManager *LPM, 4634b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick SmallVectorImpl<WeakVH> &Dead) { 4644b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick bool Changed = false; 4654b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ++I) { 466bddb7f82103deb226baa6793f41c5961661167e7Andrew Trick Changed |= simplifyUsersOfIV(cast<PHINode>(I), SE, LPM, Dead); 4674b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick } 4684b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick return Changed; 4694b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick} 4704b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 4714b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick} // namespace llvm 472