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[LV] Clarify code in isPredicatedInst (NFC) #134251

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Merged
artagnon merged 1 commit into from
Apr 8, 2025
Merged

[LV] Clarify code in isPredicatedInst (NFC) #134251

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8 changes: 5 additions & 3 deletions llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3244,11 +3244,9 @@ bool LoopVectorizationCostModel::isScalarWithPredication(

// TODO: Fold into LoopVectorizationLegality::isMaskRequired.
bool LoopVectorizationCostModel::isPredicatedInst(Instruction *I) const {
// If predication is not needed, avoid it.
// TODO: We can use the loop-preheader as context point here and get
// context sensitive reasoning for isSafeToSpeculativelyExecute.
if (!blockNeedsPredicationForAnyReason(I->getParent()) ||
isSafeToSpeculativelyExecute(I) ||
if (isSafeToSpeculativelyExecute(I) ||
(isa<LoadInst, StoreInst, CallInst>(I) && !Legal->isMaskRequired(I)) ||
isa<BranchInst, SwitchInst, PHINode, AllocaInst>(I))
return false;
Expand All @@ -3258,6 +3256,10 @@ bool LoopVectorizationCostModel::isPredicatedInst(Instruction *I) const {
if (Legal->blockNeedsPredication(I->getParent()))
return true;

// If we're not folding the tail by masking, predication is unnecessary.
if (!foldTailByMasking())
return false;

// All that remain are instructions with side-effects originally executed in
// the loop unconditionally, but now execute under a tail-fold mask (only)
// having at least one active lane (the first). If the side-effects of the
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