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[SCEV] Cleanup doesIVOverflowOnX checks [NFC] 

Stylistic changes only.
1) Don't pass a parameter just to do an early exit.
2) Use a name which matches actual behavior.
This commit is contained in:
Philip Reames 2021-05-25 10:11:17 -07:00
parent 472c009139
commit aabca2d1da
2 changed files with 16 additions and 19 deletions
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10
llvm/include/llvm/Analysis/ScalarEvolution.h
View File

@ -2002,15 +2002,13 @@ private:
/// Verify if an linear IV with positive stride can overflow when in a
/// less-than comparison, knowing the invariant term of the comparison,
/// the stride and the knowledge of NSW/NUW flags on the recurrence.
bool doesIVOverflowOnLT(const SCEV *RHS, const SCEV *Stride, bool IsSigned,
bool NoWrap);
/// the stride.
bool canIVOverflowOnLT(const SCEV *RHS, const SCEV *Stride, bool IsSigned);
/// Verify if an linear IV with negative stride can overflow when in a
/// greater-than comparison, knowing the invariant term of the comparison,
/// the stride and the knowledge of NSW/NUW flags on the recurrence.
bool doesIVOverflowOnGT(const SCEV *RHS, const SCEV *Stride, bool IsSigned,
bool NoWrap);
/// the stride.
bool canIVOverflowOnGT(const SCEV *RHS, const SCEV *Stride, bool IsSigned);
/// Get add expr already created or create a new one.
const SCEV *getOrCreateAddExpr(ArrayRef<const SCEV *> Ops,

25
llvm/lib/Analysis/ScalarEvolution.cpp
View File

@ -11183,12 +11183,10 @@ bool ScalarEvolution::isImpliedCondOperandsViaRanges(ICmpInst::Predicate Pred,
return LHSRange.icmp(Pred, ConstRHS);
}
bool ScalarEvolution::doesIVOverflowOnLT(const SCEV *RHS, const SCEV *Stride,
bool IsSigned, bool NoWrap) {
bool ScalarEvolution::canIVOverflowOnLT(const SCEV *RHS, const SCEV *Stride,
bool IsSigned) {
assert(isKnownPositive(Stride) && "Positive stride expected!");
if (NoWrap) return false;
unsigned BitWidth = getTypeSizeInBits(RHS->getType());
const SCEV *One = getOne(Stride->getType());
@ -11209,10 +11207,9 @@ bool ScalarEvolution::doesIVOverflowOnLT(const SCEV *RHS, const SCEV *Stride,
return (std::move(MaxValue) - MaxStrideMinusOne).ult(MaxRHS);
}
bool ScalarEvolution::doesIVOverflowOnGT(const SCEV *RHS, const SCEV *Stride,
bool IsSigned, bool NoWrap) {
if (NoWrap) return false;
bool ScalarEvolution::canIVOverflowOnGT(const SCEV *RHS, const SCEV *Stride,
bool IsSigned) {
unsigned BitWidth = getTypeSizeInBits(RHS->getType());
const SCEV *One = getOne(Stride->getType());
@ -11357,13 +11354,14 @@ ScalarEvolution::howManyLessThans(const SCEV *LHS, const SCEV *RHS,
if (PredicatedIV || !NoWrap || isKnownNonPositive(Stride) ||
!loopHasNoSideEffects(L))
return getCouldNotCompute();
} else if (!Stride->isOne() &&
doesIVOverflowOnLT(RHS, Stride, IsSigned, NoWrap))
} else if (!Stride->isOne() && !NoWrap) {
// Avoid proven overflow cases: this will ensure that the backedge taken
// count will not generate any unsigned overflow. Relaxed no-overflow
// conditions exploit NoWrapFlags, allowing to optimize in presence of
// undefined behaviors like the case of C language.
return getCouldNotCompute();
if (canIVOverflowOnLT(RHS, Stride, IsSigned))
return getCouldNotCompute();
}
ICmpInst::Predicate Cond = IsSigned ? ICmpInst::ICMP_SLT
: ICmpInst::ICMP_ULT;
@ -11462,8 +11460,9 @@ ScalarEvolution::howManyGreaterThans(const SCEV *LHS, const SCEV *RHS,
// will not generate any unsigned overflow. Relaxed no-overflow conditions
// exploit NoWrapFlags, allowing to optimize in presence of undefined
// behaviors like the case of C language.
if (!Stride->isOne() && doesIVOverflowOnGT(RHS, Stride, IsSigned, NoWrap))
return getCouldNotCompute();
if (!Stride->isOne() && !NoWrap)
if (canIVOverflowOnGT(RHS, Stride, IsSigned))
return getCouldNotCompute();
ICmpInst::Predicate Cond = IsSigned ? ICmpInst::ICMP_SGT
: ICmpInst::ICMP_UGT;