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[SLP] Exit early if MaxVF < MinVF (NFCI). #83283

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Merged
merged 5 commits into from
Mar 1, 2024
Merged

[SLP] Exit early if MaxVF < MinVF (NFCI). #83283

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3eacfa6
[SLP] Exit early if MaxVF < MinVF (NFCI).
fhahn Feb 28, 2024
2cf3548
!fixup <= -> < in debug output
fhahn Feb 28, 2024
7e52dbb
!fixup use continue instead return, scope exit to update Operands/Pre…
fhahn Feb 28, 2024
89c1415
!fixup fix formatting.
fhahn Feb 28, 2024
63b5482
Merge remote-tracking branch 'origin/main' into users/fhahn/slp-early…
fhahn Mar 1, 2024
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5 changes: 3 additions & 2 deletions llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -13925,10 +13925,11 @@ bool SLPVectorizerPass::vectorizeStores(ArrayRef<StoreInst *> Stores,
unsigned MinVF = TTI->getStoreMinimumVF(
R.getMinVF(DL->getTypeSizeInBits(ValueTy)), StoreTy, ValueTy);

if (MaxVF <= MinVF) {
if (MaxVF < MinVF) {
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I mean this change increases cases, where the vectorization may be triggered, since you're loosening the restriction. So need to add the test for such a case.

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I think I might be missing something here. The original code only guarded the debug output by this check AFAICT, but always also reached the for loop below, which would not be entered if MaxVF < MinVF.

Now the code continues early instead of reaching the for loop, so it should only restrict the cases where we execute the loop below (and could vectorize)?

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Ah, Yes, missed there were continue before.

LLVM_DEBUG(dbgs() << "SLP: Vectorization infeasible as MaxVF (" << MaxVF
<< ") <= "
<< ") < "
<< "MinVF (" << MinVF << ")\n");
continue;
}

// FIXME: Is division-by-2 the correct step? Should we assert that the
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