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-rw-r--r--contrib/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp136
1 files changed, 45 insertions, 91 deletions
diff --git a/contrib/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp b/contrib/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
index d54c09aa6ae4..3757a801d645 100644
--- a/contrib/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
+++ b/contrib/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
@@ -17,7 +17,6 @@
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
-#include "llvm/Analysis/IVUsers.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
@@ -48,22 +47,15 @@ namespace {
Loop *L;
LoopInfo *LI;
ScalarEvolution *SE;
- const DataLayout *DL; // May be NULL
SmallVectorImpl<WeakVH> &DeadInsts;
bool Changed;
public:
- SimplifyIndvar(Loop *Loop, ScalarEvolution *SE, LPPassManager *LPM,
- SmallVectorImpl<WeakVH> &Dead, IVUsers *IVU = nullptr) :
- L(Loop),
- LI(LPM->getAnalysisIfAvailable<LoopInfo>()),
- SE(SE),
- DeadInsts(Dead),
- Changed(false) {
- DataLayoutPass *DLP = LPM->getAnalysisIfAvailable<DataLayoutPass>();
- DL = DLP ? &DLP->getDataLayout() : nullptr;
+ SimplifyIndvar(Loop *Loop, ScalarEvolution *SE, LoopInfo *LI,
+ SmallVectorImpl<WeakVH> &Dead)
+ : L(Loop), LI(LI), SE(SE), DeadInsts(Dead), Changed(false) {
assert(LI && "IV simplification requires LoopInfo");
}
@@ -277,95 +269,57 @@ bool SimplifyIndvar::eliminateIVUser(Instruction *UseInst,
bool SimplifyIndvar::strengthenOverflowingOperation(BinaryOperator *BO,
Value *IVOperand) {
- // Currently we only handle instructions of the form "add <indvar> <value>"
- unsigned Op = BO->getOpcode();
- if (Op != Instruction::Add)
+ // Fastpath: we don't have any work to do if `BO` is `nuw` and `nsw`.
+ if (BO->hasNoUnsignedWrap() && BO->hasNoSignedWrap())
return false;
- // If BO is already both nuw and nsw then there is nothing left to do
- if (BO->hasNoUnsignedWrap() && BO->hasNoSignedWrap())
+ const SCEV *(ScalarEvolution::*GetExprForBO)(const SCEV *, const SCEV *,
+ SCEV::NoWrapFlags);
+
+ switch (BO->getOpcode()) {
+ default:
return false;
- IntegerType *IT = cast<IntegerType>(IVOperand->getType());
- Value *OtherOperand = nullptr;
- if (BO->getOperand(0) == IVOperand) {
- OtherOperand = BO->getOperand(1);
- } else {
- assert(BO->getOperand(1) == IVOperand && "only other use!");
- OtherOperand = BO->getOperand(0);
+ case Instruction::Add:
+ GetExprForBO = &ScalarEvolution::getAddExpr;
+ break;
+
+ case Instruction::Sub:
+ GetExprForBO = &ScalarEvolution::getMinusSCEV;
+ break;
+
+ case Instruction::Mul:
+ GetExprForBO = &ScalarEvolution::getMulExpr;
+ break;
}
- bool Changed = false;
- const SCEV *OtherOpSCEV = SE->getSCEV(OtherOperand);
- if (OtherOpSCEV == SE->getCouldNotCompute())
- return false;
+ unsigned BitWidth = cast<IntegerType>(BO->getType())->getBitWidth();
+ Type *WideTy = IntegerType::get(BO->getContext(), BitWidth * 2);
+ const SCEV *LHS = SE->getSCEV(BO->getOperand(0));
+ const SCEV *RHS = SE->getSCEV(BO->getOperand(1));
- const SCEV *IVOpSCEV = SE->getSCEV(IVOperand);
- const SCEV *ZeroSCEV = SE->getConstant(IVOpSCEV->getType(), 0);
+ bool Changed = false;
- if (!BO->hasNoSignedWrap()) {
- // Upgrade the add to an "add nsw" if we can prove that it will never
- // sign-overflow or sign-underflow.
-
- const SCEV *SignedMax =
- SE->getConstant(APInt::getSignedMaxValue(IT->getBitWidth()));
- const SCEV *SignedMin =
- SE->getConstant(APInt::getSignedMinValue(IT->getBitWidth()));
-
- // The addition "IVOperand + OtherOp" does not sign-overflow if the result
- // is sign-representable in 2's complement in the given bit-width.
- //
- // If OtherOp is SLT 0, then for an IVOperand in [SignedMin - OtherOp,
- // SignedMax], "IVOperand + OtherOp" is in [SignedMin, SignedMax + OtherOp].
- // Everything in [SignedMin, SignedMax + OtherOp] is representable since
- // SignedMax + OtherOp is at least -1.
- //
- // If OtherOp is SGE 0, then for an IVOperand in [SignedMin, SignedMax -
- // OtherOp], "IVOperand + OtherOp" is in [SignedMin + OtherOp, SignedMax].
- // Everything in [SignedMin + OtherOp, SignedMax] is representable since
- // SignedMin + OtherOp is at most -1.
- //
- // It follows that for all values of IVOperand in [SignedMin - smin(0,
- // OtherOp), SignedMax - smax(0, OtherOp)] the result of the add is
- // representable (i.e. there is no sign-overflow).
-
- const SCEV *UpperDelta = SE->getSMaxExpr(ZeroSCEV, OtherOpSCEV);
- const SCEV *UpperLimit = SE->getMinusSCEV(SignedMax, UpperDelta);
-
- bool NeverSignedOverflows =
- SE->isKnownPredicate(ICmpInst::ICMP_SLE, IVOpSCEV, UpperLimit);
-
- if (NeverSignedOverflows) {
- const SCEV *LowerDelta = SE->getSMinExpr(ZeroSCEV, OtherOpSCEV);
- const SCEV *LowerLimit = SE->getMinusSCEV(SignedMin, LowerDelta);
-
- bool NeverSignedUnderflows =
- SE->isKnownPredicate(ICmpInst::ICMP_SGE, IVOpSCEV, LowerLimit);
- if (NeverSignedUnderflows) {
- BO->setHasNoSignedWrap(true);
- Changed = true;
- }
+ if (!BO->hasNoUnsignedWrap()) {
+ const SCEV *ExtendAfterOp = SE->getZeroExtendExpr(SE->getSCEV(BO), WideTy);
+ const SCEV *OpAfterExtend = (SE->*GetExprForBO)(
+ SE->getZeroExtendExpr(LHS, WideTy), SE->getZeroExtendExpr(RHS, WideTy),
+ SCEV::FlagAnyWrap);
+ if (ExtendAfterOp == OpAfterExtend) {
+ BO->setHasNoUnsignedWrap();
+ SE->forgetValue(BO);
+ Changed = true;
}
}
- if (!BO->hasNoUnsignedWrap()) {
- // Upgrade the add computing "IVOperand + OtherOp" to an "add nuw" if we can
- // prove that it will never unsigned-overflow (i.e. the result will always
- // be representable in the given bit-width).
- //
- // "IVOperand + OtherOp" is unsigned-representable in 2's complement iff it
- // does not produce a carry. "IVOperand + OtherOp" produces no carry iff
- // IVOperand ULE (UnsignedMax - OtherOp).
-
- const SCEV *UnsignedMax =
- SE->getConstant(APInt::getMaxValue(IT->getBitWidth()));
- const SCEV *UpperLimit = SE->getMinusSCEV(UnsignedMax, OtherOpSCEV);
-
- bool NeverUnsignedOverflows =
- SE->isKnownPredicate(ICmpInst::ICMP_ULE, IVOpSCEV, UpperLimit);
-
- if (NeverUnsignedOverflows) {
- BO->setHasNoUnsignedWrap(true);
+ if (!BO->hasNoSignedWrap()) {
+ const SCEV *ExtendAfterOp = SE->getSignExtendExpr(SE->getSCEV(BO), WideTy);
+ const SCEV *OpAfterExtend = (SE->*GetExprForBO)(
+ SE->getSignExtendExpr(LHS, WideTy), SE->getSignExtendExpr(RHS, WideTy),
+ SCEV::FlagAnyWrap);
+ if (ExtendAfterOp == OpAfterExtend) {
+ BO->setHasNoSignedWrap();
+ SE->forgetValue(BO);
Changed = true;
}
}
@@ -562,8 +516,8 @@ void IVVisitor::anchor() { }
bool simplifyUsersOfIV(PHINode *CurrIV, ScalarEvolution *SE, LPPassManager *LPM,
SmallVectorImpl<WeakVH> &Dead, IVVisitor *V)
{
- LoopInfo *LI = &LPM->getAnalysis<LoopInfo>();
- SimplifyIndvar SIV(LI->getLoopFor(CurrIV->getParent()), SE, LPM, Dead);
+ LoopInfo *LI = &LPM->getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
+ SimplifyIndvar SIV(LI->getLoopFor(CurrIV->getParent()), SE, LI, Dead);
SIV.simplifyUsers(CurrIV, V);
return SIV.hasChanged();
}
generated by cgit v1.2.3 (git 2.25.1) at 2025-10-31 09:00:38 +0000