1 //===-- SimplifyIndVar.cpp - Induction variable simplification ------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements induction variable simplification. It does
11 // not define any actual pass or policy, but provides a single function to
12 // simplify a loop's induction variables based on ScalarEvolution.
14 //===----------------------------------------------------------------------===//
16 #include "llvm/Transforms/Utils/SimplifyIndVar.h"
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/ADT/Statistic.h"
20 #include "llvm/Analysis/LoopInfo.h"
21 #include "llvm/Analysis/LoopPass.h"
22 #include "llvm/Analysis/ScalarEvolutionExpressions.h"
23 #include "llvm/IR/DataLayout.h"
24 #include "llvm/IR/Dominators.h"
25 #include "llvm/IR/IRBuilder.h"
26 #include "llvm/IR/Instructions.h"
27 #include "llvm/IR/IntrinsicInst.h"
28 #include "llvm/Support/Debug.h"
29 #include "llvm/Support/raw_ostream.h"
33 #define DEBUG_TYPE "indvars"
35 STATISTIC(NumElimIdentity, "Number of IV identities eliminated");
36 STATISTIC(NumElimOperand, "Number of IV operands folded into a use");
37 STATISTIC(NumElimRem , "Number of IV remainder operations eliminated");
40 "Number of IV signed division operations converted to unsigned division");
41 STATISTIC(NumElimCmp , "Number of IV comparisons eliminated");
44 /// This is a utility for simplifying induction variables
45 /// based on ScalarEvolution. It is the primary instrument of the
46 /// IndvarSimplify pass, but it may also be directly invoked to cleanup after
47 /// other loop passes that preserve SCEV.
48 class SimplifyIndvar {
54 SmallVectorImpl<WeakTrackingVH> &DeadInsts;
59 SimplifyIndvar(Loop *Loop, ScalarEvolution *SE, DominatorTree *DT,
60 LoopInfo *LI, SmallVectorImpl<WeakTrackingVH> &Dead)
61 : L(Loop), LI(LI), SE(SE), DT(DT), DeadInsts(Dead), Changed(false) {
62 assert(LI && "IV simplification requires LoopInfo");
65 bool hasChanged() const { return Changed; }
67 /// Iteratively perform simplification on a worklist of users of the
68 /// specified induction variable. This is the top-level driver that applies
69 /// all simplifications to users of an IV.
70 void simplifyUsers(PHINode *CurrIV, IVVisitor *V = nullptr);
72 Value *foldIVUser(Instruction *UseInst, Instruction *IVOperand);
74 bool eliminateIdentitySCEV(Instruction *UseInst, Instruction *IVOperand);
76 bool eliminateOverflowIntrinsic(CallInst *CI);
77 bool eliminateIVUser(Instruction *UseInst, Instruction *IVOperand);
78 void eliminateIVComparison(ICmpInst *ICmp, Value *IVOperand);
79 void eliminateIVRemainder(BinaryOperator *Rem, Value *IVOperand,
81 bool eliminateSDiv(BinaryOperator *SDiv);
82 bool strengthenOverflowingOperation(BinaryOperator *OBO, Value *IVOperand);
86 /// Fold an IV operand into its use. This removes increments of an
87 /// aligned IV when used by a instruction that ignores the low bits.
89 /// IVOperand is guaranteed SCEVable, but UseInst may not be.
91 /// Return the operand of IVOperand for this induction variable if IVOperand can
92 /// be folded (in case more folding opportunities have been exposed).
93 /// Otherwise return null.
94 Value *SimplifyIndvar::foldIVUser(Instruction *UseInst, Instruction *IVOperand) {
95 Value *IVSrc = nullptr;
97 const SCEV *FoldedExpr = nullptr;
98 switch (UseInst->getOpcode()) {
101 case Instruction::UDiv:
102 case Instruction::LShr:
103 // We're only interested in the case where we know something about
104 // the numerator and have a constant denominator.
105 if (IVOperand != UseInst->getOperand(OperIdx) ||
106 !isa<ConstantInt>(UseInst->getOperand(1)))
109 // Attempt to fold a binary operator with constant operand.
110 // e.g. ((I + 1) >> 2) => I >> 2
111 if (!isa<BinaryOperator>(IVOperand)
112 || !isa<ConstantInt>(IVOperand->getOperand(1)))
115 IVSrc = IVOperand->getOperand(0);
116 // IVSrc must be the (SCEVable) IV, since the other operand is const.
117 assert(SE->isSCEVable(IVSrc->getType()) && "Expect SCEVable IV operand");
119 ConstantInt *D = cast<ConstantInt>(UseInst->getOperand(1));
120 if (UseInst->getOpcode() == Instruction::LShr) {
121 // Get a constant for the divisor. See createSCEV.
122 uint32_t BitWidth = cast<IntegerType>(UseInst->getType())->getBitWidth();
123 if (D->getValue().uge(BitWidth))
126 D = ConstantInt::get(UseInst->getContext(),
127 APInt::getOneBitSet(BitWidth, D->getZExtValue()));
129 FoldedExpr = SE->getUDivExpr(SE->getSCEV(IVSrc), SE->getSCEV(D));
131 // We have something that might fold it's operand. Compare SCEVs.
132 if (!SE->isSCEVable(UseInst->getType()))
135 // Bypass the operand if SCEV can prove it has no effect.
136 if (SE->getSCEV(UseInst) != FoldedExpr)
139 DEBUG(dbgs() << "INDVARS: Eliminated IV operand: " << *IVOperand
140 << " -> " << *UseInst << '\n');
142 UseInst->setOperand(OperIdx, IVSrc);
143 assert(SE->getSCEV(UseInst) == FoldedExpr && "bad SCEV with folded oper");
147 if (IVOperand->use_empty())
148 DeadInsts.emplace_back(IVOperand);
152 /// SimplifyIVUsers helper for eliminating useless
153 /// comparisons against an induction variable.
154 void SimplifyIndvar::eliminateIVComparison(ICmpInst *ICmp, Value *IVOperand) {
155 unsigned IVOperIdx = 0;
156 ICmpInst::Predicate Pred = ICmp->getPredicate();
157 if (IVOperand != ICmp->getOperand(0)) {
159 assert(IVOperand == ICmp->getOperand(1) && "Can't find IVOperand");
161 Pred = ICmpInst::getSwappedPredicate(Pred);
164 // Get the SCEVs for the ICmp operands.
165 const SCEV *S = SE->getSCEV(ICmp->getOperand(IVOperIdx));
166 const SCEV *X = SE->getSCEV(ICmp->getOperand(1 - IVOperIdx));
168 // Simplify unnecessary loops away.
169 const Loop *ICmpLoop = LI->getLoopFor(ICmp->getParent());
170 S = SE->getSCEVAtScope(S, ICmpLoop);
171 X = SE->getSCEVAtScope(X, ICmpLoop);
173 ICmpInst::Predicate InvariantPredicate;
174 const SCEV *InvariantLHS, *InvariantRHS;
176 // If the condition is always true or always false, replace it with
178 if (SE->isKnownPredicate(Pred, S, X)) {
179 ICmp->replaceAllUsesWith(ConstantInt::getTrue(ICmp->getContext()));
180 DeadInsts.emplace_back(ICmp);
181 DEBUG(dbgs() << "INDVARS: Eliminated comparison: " << *ICmp << '\n');
182 } else if (SE->isKnownPredicate(ICmpInst::getInversePredicate(Pred), S, X)) {
183 ICmp->replaceAllUsesWith(ConstantInt::getFalse(ICmp->getContext()));
184 DeadInsts.emplace_back(ICmp);
185 DEBUG(dbgs() << "INDVARS: Eliminated comparison: " << *ICmp << '\n');
186 } else if (isa<PHINode>(IVOperand) &&
187 SE->isLoopInvariantPredicate(Pred, S, X, L, InvariantPredicate,
188 InvariantLHS, InvariantRHS)) {
190 // Rewrite the comparison to a loop invariant comparison if it can be done
191 // cheaply, where cheaply means "we don't need to emit any new
194 Value *NewLHS = nullptr, *NewRHS = nullptr;
196 if (S == InvariantLHS || X == InvariantLHS)
198 ICmp->getOperand(S == InvariantLHS ? IVOperIdx : (1 - IVOperIdx));
200 if (S == InvariantRHS || X == InvariantRHS)
202 ICmp->getOperand(S == InvariantRHS ? IVOperIdx : (1 - IVOperIdx));
204 auto *PN = cast<PHINode>(IVOperand);
205 for (unsigned i = 0, e = PN->getNumIncomingValues();
206 i != e && (!NewLHS || !NewRHS);
209 // If this is a value incoming from the backedge, then it cannot be a loop
210 // invariant value (since we know that IVOperand is an induction variable).
211 if (L->contains(PN->getIncomingBlock(i)))
214 // NB! This following assert does not fundamentally have to be true, but
215 // it is true today given how SCEV analyzes induction variables.
216 // Specifically, today SCEV will *not* recognize %iv as an induction
217 // variable in the following case:
219 // define void @f(i32 %k) {
221 // br i1 undef, label %r, label %l
224 // %k.inc.l = add i32 %k, 1
228 // %k.inc.r = add i32 %k, 1
232 // %iv = phi i32 [ %k.inc.l, %l ], [ %k.inc.r, %r ], [ %iv.inc, %loop ]
233 // %iv.inc = add i32 %iv, 1
237 // but if it starts to, at some point, then the assertion below will have
238 // to be changed to a runtime check.
240 Value *Incoming = PN->getIncomingValue(i);
243 if (auto *I = dyn_cast<Instruction>(Incoming))
244 assert(DT->dominates(I, ICmp) && "Should be a unique loop dominating value!");
247 const SCEV *IncomingS = SE->getSCEV(Incoming);
249 if (!NewLHS && IncomingS == InvariantLHS)
251 if (!NewRHS && IncomingS == InvariantRHS)
255 if (!NewLHS || !NewRHS)
256 // We could not find an existing value to replace either LHS or RHS.
257 // Generating new instructions has subtler tradeoffs, so avoid doing that
261 DEBUG(dbgs() << "INDVARS: Simplified comparison: " << *ICmp << '\n');
262 ICmp->setPredicate(InvariantPredicate);
263 ICmp->setOperand(0, NewLHS);
264 ICmp->setOperand(1, NewRHS);
272 bool SimplifyIndvar::eliminateSDiv(BinaryOperator *SDiv) {
273 // Get the SCEVs for the ICmp operands.
274 auto *N = SE->getSCEV(SDiv->getOperand(0));
275 auto *D = SE->getSCEV(SDiv->getOperand(1));
277 // Simplify unnecessary loops away.
278 const Loop *L = LI->getLoopFor(SDiv->getParent());
279 N = SE->getSCEVAtScope(N, L);
280 D = SE->getSCEVAtScope(D, L);
282 // Replace sdiv by udiv if both of the operands are non-negative
283 if (SE->isKnownNonNegative(N) && SE->isKnownNonNegative(D)) {
284 auto *UDiv = BinaryOperator::Create(
285 BinaryOperator::UDiv, SDiv->getOperand(0), SDiv->getOperand(1),
286 SDiv->getName() + ".udiv", SDiv);
287 UDiv->setIsExact(SDiv->isExact());
288 SDiv->replaceAllUsesWith(UDiv);
289 DEBUG(dbgs() << "INDVARS: Simplified sdiv: " << *SDiv << '\n');
292 DeadInsts.push_back(SDiv);
299 /// SimplifyIVUsers helper for eliminating useless
300 /// remainder operations operating on an induction variable.
301 void SimplifyIndvar::eliminateIVRemainder(BinaryOperator *Rem,
304 // We're only interested in the case where we know something about
306 if (IVOperand != Rem->getOperand(0))
309 // Get the SCEVs for the ICmp operands.
310 const SCEV *S = SE->getSCEV(Rem->getOperand(0));
311 const SCEV *X = SE->getSCEV(Rem->getOperand(1));
313 // Simplify unnecessary loops away.
314 const Loop *ICmpLoop = LI->getLoopFor(Rem->getParent());
315 S = SE->getSCEVAtScope(S, ICmpLoop);
316 X = SE->getSCEVAtScope(X, ICmpLoop);
318 // i % n --> i if i is in [0,n).
319 if ((!IsSigned || SE->isKnownNonNegative(S)) &&
320 SE->isKnownPredicate(IsSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
322 Rem->replaceAllUsesWith(Rem->getOperand(0));
324 // (i+1) % n --> (i+1)==n?0:(i+1) if i is in [0,n).
325 const SCEV *LessOne = SE->getMinusSCEV(S, SE->getOne(S->getType()));
326 if (IsSigned && !SE->isKnownNonNegative(LessOne))
329 if (!SE->isKnownPredicate(IsSigned ?
330 ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
334 ICmpInst *ICmp = new ICmpInst(Rem, ICmpInst::ICMP_EQ,
335 Rem->getOperand(0), Rem->getOperand(1));
337 SelectInst::Create(ICmp,
338 ConstantInt::get(Rem->getType(), 0),
339 Rem->getOperand(0), "tmp", Rem);
340 Rem->replaceAllUsesWith(Sel);
343 DEBUG(dbgs() << "INDVARS: Simplified rem: " << *Rem << '\n');
346 DeadInsts.emplace_back(Rem);
349 bool SimplifyIndvar::eliminateOverflowIntrinsic(CallInst *CI) {
350 auto *F = CI->getCalledFunction();
354 typedef const SCEV *(ScalarEvolution::*OperationFunctionTy)(
355 const SCEV *, const SCEV *, SCEV::NoWrapFlags);
356 typedef const SCEV *(ScalarEvolution::*ExtensionFunctionTy)(
357 const SCEV *, Type *);
359 OperationFunctionTy Operation;
360 ExtensionFunctionTy Extension;
362 Instruction::BinaryOps RawOp;
364 // We always have exactly one of nsw or nuw. If NoSignedOverflow is false, we
366 bool NoSignedOverflow;
368 switch (F->getIntrinsicID()) {
372 case Intrinsic::sadd_with_overflow:
373 Operation = &ScalarEvolution::getAddExpr;
374 Extension = &ScalarEvolution::getSignExtendExpr;
375 RawOp = Instruction::Add;
376 NoSignedOverflow = true;
379 case Intrinsic::uadd_with_overflow:
380 Operation = &ScalarEvolution::getAddExpr;
381 Extension = &ScalarEvolution::getZeroExtendExpr;
382 RawOp = Instruction::Add;
383 NoSignedOverflow = false;
386 case Intrinsic::ssub_with_overflow:
387 Operation = &ScalarEvolution::getMinusSCEV;
388 Extension = &ScalarEvolution::getSignExtendExpr;
389 RawOp = Instruction::Sub;
390 NoSignedOverflow = true;
393 case Intrinsic::usub_with_overflow:
394 Operation = &ScalarEvolution::getMinusSCEV;
395 Extension = &ScalarEvolution::getZeroExtendExpr;
396 RawOp = Instruction::Sub;
397 NoSignedOverflow = false;
401 const SCEV *LHS = SE->getSCEV(CI->getArgOperand(0));
402 const SCEV *RHS = SE->getSCEV(CI->getArgOperand(1));
404 auto *NarrowTy = cast<IntegerType>(LHS->getType());
406 IntegerType::get(NarrowTy->getContext(), NarrowTy->getBitWidth() * 2);
409 (SE->*Extension)((SE->*Operation)(LHS, RHS, SCEV::FlagAnyWrap), WideTy);
411 (SE->*Operation)((SE->*Extension)(LHS, WideTy),
412 (SE->*Extension)(RHS, WideTy), SCEV::FlagAnyWrap);
417 // Proved no overflow, nuke the overflow check and, if possible, the overflow
418 // intrinsic as well.
420 BinaryOperator *NewResult = BinaryOperator::Create(
421 RawOp, CI->getArgOperand(0), CI->getArgOperand(1), "", CI);
423 if (NoSignedOverflow)
424 NewResult->setHasNoSignedWrap(true);
426 NewResult->setHasNoUnsignedWrap(true);
428 SmallVector<ExtractValueInst *, 4> ToDelete;
430 for (auto *U : CI->users()) {
431 if (auto *EVI = dyn_cast<ExtractValueInst>(U)) {
432 if (EVI->getIndices()[0] == 1)
433 EVI->replaceAllUsesWith(ConstantInt::getFalse(CI->getContext()));
435 assert(EVI->getIndices()[0] == 0 && "Only two possibilities!");
436 EVI->replaceAllUsesWith(NewResult);
438 ToDelete.push_back(EVI);
442 for (auto *EVI : ToDelete)
443 EVI->eraseFromParent();
446 CI->eraseFromParent();
451 /// Eliminate an operation that consumes a simple IV and has no observable
452 /// side-effect given the range of IV values. IVOperand is guaranteed SCEVable,
453 /// but UseInst may not be.
454 bool SimplifyIndvar::eliminateIVUser(Instruction *UseInst,
455 Instruction *IVOperand) {
456 if (ICmpInst *ICmp = dyn_cast<ICmpInst>(UseInst)) {
457 eliminateIVComparison(ICmp, IVOperand);
460 if (BinaryOperator *Bin = dyn_cast<BinaryOperator>(UseInst)) {
461 bool IsSRem = Bin->getOpcode() == Instruction::SRem;
462 if (IsSRem || Bin->getOpcode() == Instruction::URem) {
463 eliminateIVRemainder(Bin, IVOperand, IsSRem);
467 if (Bin->getOpcode() == Instruction::SDiv)
468 return eliminateSDiv(Bin);
471 if (auto *CI = dyn_cast<CallInst>(UseInst))
472 if (eliminateOverflowIntrinsic(CI))
475 if (eliminateIdentitySCEV(UseInst, IVOperand))
481 /// Eliminate any operation that SCEV can prove is an identity function.
482 bool SimplifyIndvar::eliminateIdentitySCEV(Instruction *UseInst,
483 Instruction *IVOperand) {
484 if (!SE->isSCEVable(UseInst->getType()) ||
485 (UseInst->getType() != IVOperand->getType()) ||
486 (SE->getSCEV(UseInst) != SE->getSCEV(IVOperand)))
489 // getSCEV(X) == getSCEV(Y) does not guarantee that X and Y are related in the
490 // dominator tree, even if X is an operand to Y. For instance, in
492 // %iv = phi i32 {0,+,1}
493 // br %cond, label %left, label %merge
496 // %X = add i32 %iv, 0
500 // %M = phi (%X, %iv)
502 // getSCEV(%M) == getSCEV(%X) == {0,+,1}, but %X does not dominate %M, and
503 // %M.replaceAllUsesWith(%X) would be incorrect.
505 if (isa<PHINode>(UseInst))
506 // If UseInst is not a PHI node then we know that IVOperand dominates
507 // UseInst directly from the legality of SSA.
508 if (!DT || !DT->dominates(IVOperand, UseInst))
511 if (!LI->replacementPreservesLCSSAForm(UseInst, IVOperand))
514 DEBUG(dbgs() << "INDVARS: Eliminated identity: " << *UseInst << '\n');
516 UseInst->replaceAllUsesWith(IVOperand);
519 DeadInsts.emplace_back(UseInst);
523 /// Annotate BO with nsw / nuw if it provably does not signed-overflow /
524 /// unsigned-overflow. Returns true if anything changed, false otherwise.
525 bool SimplifyIndvar::strengthenOverflowingOperation(BinaryOperator *BO,
528 // Fastpath: we don't have any work to do if `BO` is `nuw` and `nsw`.
529 if (BO->hasNoUnsignedWrap() && BO->hasNoSignedWrap())
532 const SCEV *(ScalarEvolution::*GetExprForBO)(const SCEV *, const SCEV *,
535 switch (BO->getOpcode()) {
539 case Instruction::Add:
540 GetExprForBO = &ScalarEvolution::getAddExpr;
543 case Instruction::Sub:
544 GetExprForBO = &ScalarEvolution::getMinusSCEV;
547 case Instruction::Mul:
548 GetExprForBO = &ScalarEvolution::getMulExpr;
552 unsigned BitWidth = cast<IntegerType>(BO->getType())->getBitWidth();
553 Type *WideTy = IntegerType::get(BO->getContext(), BitWidth * 2);
554 const SCEV *LHS = SE->getSCEV(BO->getOperand(0));
555 const SCEV *RHS = SE->getSCEV(BO->getOperand(1));
557 bool Changed = false;
559 if (!BO->hasNoUnsignedWrap()) {
560 const SCEV *ExtendAfterOp = SE->getZeroExtendExpr(SE->getSCEV(BO), WideTy);
561 const SCEV *OpAfterExtend = (SE->*GetExprForBO)(
562 SE->getZeroExtendExpr(LHS, WideTy), SE->getZeroExtendExpr(RHS, WideTy),
564 if (ExtendAfterOp == OpAfterExtend) {
565 BO->setHasNoUnsignedWrap();
571 if (!BO->hasNoSignedWrap()) {
572 const SCEV *ExtendAfterOp = SE->getSignExtendExpr(SE->getSCEV(BO), WideTy);
573 const SCEV *OpAfterExtend = (SE->*GetExprForBO)(
574 SE->getSignExtendExpr(LHS, WideTy), SE->getSignExtendExpr(RHS, WideTy),
576 if (ExtendAfterOp == OpAfterExtend) {
577 BO->setHasNoSignedWrap();
586 /// Add all uses of Def to the current IV's worklist.
587 static void pushIVUsers(
589 SmallPtrSet<Instruction*,16> &Simplified,
590 SmallVectorImpl< std::pair<Instruction*,Instruction*> > &SimpleIVUsers) {
592 for (User *U : Def->users()) {
593 Instruction *UI = cast<Instruction>(U);
595 // Avoid infinite or exponential worklist processing.
596 // Also ensure unique worklist users.
597 // If Def is a LoopPhi, it may not be in the Simplified set, so check for
599 if (UI != Def && Simplified.insert(UI).second)
600 SimpleIVUsers.push_back(std::make_pair(UI, Def));
604 /// Return true if this instruction generates a simple SCEV
605 /// expression in terms of that IV.
607 /// This is similar to IVUsers' isInteresting() but processes each instruction
608 /// non-recursively when the operand is already known to be a simpleIVUser.
610 static bool isSimpleIVUser(Instruction *I, const Loop *L, ScalarEvolution *SE) {
611 if (!SE->isSCEVable(I->getType()))
614 // Get the symbolic expression for this instruction.
615 const SCEV *S = SE->getSCEV(I);
617 // Only consider affine recurrences.
618 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S);
619 if (AR && AR->getLoop() == L)
625 /// Iteratively perform simplification on a worklist of users
626 /// of the specified induction variable. Each successive simplification may push
627 /// more users which may themselves be candidates for simplification.
629 /// This algorithm does not require IVUsers analysis. Instead, it simplifies
630 /// instructions in-place during analysis. Rather than rewriting induction
631 /// variables bottom-up from their users, it transforms a chain of IVUsers
632 /// top-down, updating the IR only when it encounters a clear optimization
635 /// Once DisableIVRewrite is default, LSR will be the only client of IVUsers.
637 void SimplifyIndvar::simplifyUsers(PHINode *CurrIV, IVVisitor *V) {
638 if (!SE->isSCEVable(CurrIV->getType()))
641 // Instructions processed by SimplifyIndvar for CurrIV.
642 SmallPtrSet<Instruction*,16> Simplified;
644 // Use-def pairs if IV users waiting to be processed for CurrIV.
645 SmallVector<std::pair<Instruction*, Instruction*>, 8> SimpleIVUsers;
647 // Push users of the current LoopPhi. In rare cases, pushIVUsers may be
648 // called multiple times for the same LoopPhi. This is the proper thing to
649 // do for loop header phis that use each other.
650 pushIVUsers(CurrIV, Simplified, SimpleIVUsers);
652 while (!SimpleIVUsers.empty()) {
653 std::pair<Instruction*, Instruction*> UseOper =
654 SimpleIVUsers.pop_back_val();
655 Instruction *UseInst = UseOper.first;
657 // Bypass back edges to avoid extra work.
658 if (UseInst == CurrIV) continue;
660 Instruction *IVOperand = UseOper.second;
661 for (unsigned N = 0; IVOperand; ++N) {
662 assert(N <= Simplified.size() && "runaway iteration");
664 Value *NewOper = foldIVUser(UseOper.first, IVOperand);
666 break; // done folding
667 IVOperand = dyn_cast<Instruction>(NewOper);
672 if (eliminateIVUser(UseOper.first, IVOperand)) {
673 pushIVUsers(IVOperand, Simplified, SimpleIVUsers);
677 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(UseOper.first)) {
678 if (isa<OverflowingBinaryOperator>(BO) &&
679 strengthenOverflowingOperation(BO, IVOperand)) {
680 // re-queue uses of the now modified binary operator and fall
681 // through to the checks that remain.
682 pushIVUsers(IVOperand, Simplified, SimpleIVUsers);
686 CastInst *Cast = dyn_cast<CastInst>(UseOper.first);
691 if (isSimpleIVUser(UseOper.first, L, SE)) {
692 pushIVUsers(UseOper.first, Simplified, SimpleIVUsers);
699 void IVVisitor::anchor() { }
701 /// Simplify instructions that use this induction variable
702 /// by using ScalarEvolution to analyze the IV's recurrence.
703 bool simplifyUsersOfIV(PHINode *CurrIV, ScalarEvolution *SE, DominatorTree *DT,
704 LoopInfo *LI, SmallVectorImpl<WeakTrackingVH> &Dead,
706 SimplifyIndvar SIV(LI->getLoopFor(CurrIV->getParent()), SE, DT, LI, Dead);
707 SIV.simplifyUsers(CurrIV, V);
708 return SIV.hasChanged();
711 /// Simplify users of induction variables within this
712 /// loop. This does not actually change or add IVs.
713 bool simplifyLoopIVs(Loop *L, ScalarEvolution *SE, DominatorTree *DT,
714 LoopInfo *LI, SmallVectorImpl<WeakTrackingVH> &Dead) {
715 bool Changed = false;
716 for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ++I) {
717 Changed |= simplifyUsersOfIV(cast<PHINode>(I), SE, DT, LI, Dead);