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LAA: scope responsibility of isNoWrapAddRec (NFC) #127479

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Merged
merged 2 commits into from
Feb 17, 2025
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LAA: scope responsibility of isNoWrapAddRec (NFC) #127479

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f59af3b
LAA: drop unnecessary args, clarifying APIs
artagnon Feb 17, 2025
a579ced
LAA: address review
artagnon Feb 17, 2025
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34 changes: 17 additions & 17 deletions llvm/lib/Analysis/LoopAccessAnalysis.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -793,7 +793,8 @@ class AccessAnalysis {

} // end anonymous namespace

/// Try to compute the stride for \p AR. Used by getPtrStride.
/// Try to compute a constant stride for \p AR. Used by getPtrStride and
/// isNoWrap.
static std::optional<int64_t>
getStrideFromAddRec(const SCEVAddRecExpr *AR, const Loop *Lp, Type *AccessTy,
Value *Ptr, PredicatedScalarEvolution &PSE) {
Expand Down Expand Up @@ -835,16 +836,24 @@ getStrideFromAddRec(const SCEVAddRecExpr *AR, const Loop *Lp, Type *AccessTy,
return Stride;
}

static bool isNoWrapAddRec(Value *Ptr, const SCEVAddRecExpr *AR,
PredicatedScalarEvolution &PSE, const Loop *L);
static bool isNoWrapGEP(Value *Ptr, PredicatedScalarEvolution &PSE,
const Loop *L);

/// Check whether a pointer address cannot wrap.
/// Check whether \p AR is a non-wrapping AddRec, or if \p Ptr is a non-wrapping
/// GEP.
static bool isNoWrap(PredicatedScalarEvolution &PSE, const SCEVAddRecExpr *AR,
Value *Ptr, Type *AccessTy, const Loop *L, bool Assume,
std::optional<int64_t> Stride = std::nullopt) {
// FIXME: This should probably only return true for NUW.
if (AR->getNoWrapFlags(SCEV::NoWrapMask))
return true;

if (PSE.hasNoOverflow(Ptr, SCEVWrapPredicate::IncrementNUSW))
return true;

// The address calculation must not wrap. Otherwise, a dependence could be
// inverted.
if (isNoWrapAddRec(Ptr, AR, PSE, L))
if (isNoWrapGEP(Ptr, PSE, L))
return true;

// An nusw getelementptr that is an AddRec cannot wrap. If it would wrap,
Expand Down Expand Up @@ -1445,18 +1454,9 @@ void AccessAnalysis::processMemAccesses() {
}
}

/// Return true if an AddRec pointer \p Ptr is unsigned non-wrapping,
/// i.e. monotonically increasing/decreasing.
static bool isNoWrapAddRec(Value *Ptr, const SCEVAddRecExpr *AR,
PredicatedScalarEvolution &PSE, const Loop *L) {

// FIXME: This should probably only return true for NUW.
if (AR->getNoWrapFlags(SCEV::NoWrapMask))
return true;

if (PSE.hasNoOverflow(Ptr, SCEVWrapPredicate::IncrementNUSW))
return true;

/// Check whether \p Ptr is non-wrapping GEP.
static bool isNoWrapGEP(Value *Ptr, PredicatedScalarEvolution &PSE,
const Loop *L) {
// Scalar evolution does not propagate the non-wrapping flags to values that
// are derived from a non-wrapping induction variable because non-wrapping
// could be flow-sensitive.
Expand Down