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[LoopIdiom] Use m_scev_AffineAddRec with Loop matcher (NFC) #141660

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Merged
merged 1 commit into from
May 28, 2025
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[LoopIdiom] Use m_scev_AffineAddRec with Loop matcher (NFC) #141660

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39 changes: 17 additions & 22 deletions llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -455,8 +455,8 @@ LoopIdiomRecognize::isLegalStore(StoreInst *SI) {
// random store we can't handle.
const SCEV *StoreEv = SE->getSCEV(StorePtr);
const SCEVConstant *Stride;
if (!match(StoreEv, m_scev_AffineAddRec(m_SCEV(), m_SCEVConstant(Stride))) ||
cast<SCEVAddRecExpr>(StoreEv)->getLoop() != CurLoop)
if (!match(StoreEv, m_scev_AffineAddRec(m_SCEV(), m_SCEVConstant(Stride),
m_SpecificLoop(CurLoop))))
return LegalStoreKind::None;

// See if the store can be turned into a memset.
Expand Down Expand Up @@ -512,9 +512,8 @@ LoopIdiomRecognize::isLegalStore(StoreInst *SI) {
const SCEV *LoadEv = SE->getSCEV(LI->getPointerOperand());

// The store and load must share the same stride.
if (!match(LoadEv,
m_scev_AffineAddRec(m_SCEV(), m_scev_Specific(Stride))) ||
cast<SCEVAddRecExpr>(LoadEv)->getLoop() != CurLoop)
if (!match(LoadEv, m_scev_AffineAddRec(m_SCEV(), m_scev_Specific(Stride),
m_SpecificLoop(CurLoop))))
return LegalStoreKind::None;

// Success. This store can be converted into a memcpy.
Expand Down Expand Up @@ -787,25 +786,22 @@ bool LoopIdiomRecognize::processLoopMemCpy(MemCpyInst *MCI,
// See if the load and store pointer expressions are AddRec like {base,+,1} on
// the current loop, which indicates a strided load and store. If we have
// something else, it's a random load or store we can't handle.
const SCEVAddRecExpr *StoreEv = dyn_cast<SCEVAddRecExpr>(SE->getSCEV(Dest));
if (!StoreEv || StoreEv->getLoop() != CurLoop || !StoreEv->isAffine())
return false;
const SCEVAddRecExpr *LoadEv = dyn_cast<SCEVAddRecExpr>(SE->getSCEV(Source));
if (!LoadEv || LoadEv->getLoop() != CurLoop || !LoadEv->isAffine())
const SCEV *StoreEv = SE->getSCEV(Dest);
const SCEV *LoadEv = SE->getSCEV(Source);
const APInt *StoreStrideValue, *LoadStrideValue;
if (!match(StoreEv,
m_scev_AffineAddRec(m_SCEV(), m_scev_APInt(StoreStrideValue),
m_SpecificLoop(CurLoop))) ||
!match(LoadEv,
m_scev_AffineAddRec(m_SCEV(), m_scev_APInt(LoadStrideValue),
m_SpecificLoop(CurLoop))))
return false;

// Reject memcpys that are so large that they overflow an unsigned.
uint64_t SizeInBytes = cast<ConstantInt>(MCI->getLength())->getZExtValue();
if ((SizeInBytes >> 32) != 0)
return false;

// Check if the stride matches the size of the memcpy. If so, then we know
// that every byte is touched in the loop.
const APInt *StoreStrideValue, *LoadStrideValue;
if (!match(StoreEv->getOperand(1), m_scev_APInt(StoreStrideValue)) ||
!match(LoadEv->getOperand(1), m_scev_APInt(LoadStrideValue)))
return false;

// Huge stride value - give up
if (StoreStrideValue->getBitWidth() > 64 ||
LoadStrideValue->getBitWidth() > 64)
Expand All @@ -830,8 +826,8 @@ bool LoopIdiomRecognize::processLoopMemCpy(MemCpyInst *MCI,

return processLoopStoreOfLoopLoad(
Dest, Source, SE->getConstant(Dest->getType(), SizeInBytes),
MCI->getDestAlign(), MCI->getSourceAlign(), MCI, MCI, StoreEv, LoadEv,
BECount);
MCI->getDestAlign(), MCI->getSourceAlign(), MCI, MCI,
cast<SCEVAddRecExpr>(StoreEv), cast<SCEVAddRecExpr>(LoadEv), BECount);
}

/// processLoopMemSet - See if this memset can be promoted to a large memset.
Expand All @@ -852,12 +848,11 @@ bool LoopIdiomRecognize::processLoopMemSet(MemSetInst *MSI,
// random store we can't handle.
const SCEV *Ev = SE->getSCEV(Pointer);
const SCEV *PointerStrideSCEV;
if (!match(Ev, m_scev_AffineAddRec(m_SCEV(), m_SCEV(PointerStrideSCEV)))) {
if (!match(Ev, m_scev_AffineAddRec(m_SCEV(), m_SCEV(PointerStrideSCEV),
m_SpecificLoop(CurLoop)))) {
LLVM_DEBUG(dbgs() << " Pointer is not affine, abort\n");
return false;
}
if (cast<SCEVAddRecExpr>(Ev)->getLoop() != CurLoop)
return false;

const SCEV *MemsetSizeSCEV = SE->getSCEV(MSI->getLength());
if (!PointerStrideSCEV || !MemsetSizeSCEV)
Expand Down