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[VPlan] Fix header phi VPInstruction verification. NFC #151472

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Merged
merged 4 commits into from
Jul 31, 2025
Merged

[VPlan] Fix header phi VPInstruction verification. NFC #151472

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1ac3071
[VPlan] Fix header phi VPInstruction verification. NFC
lukel97 Jul 31, 2025
c170996
Add unit test
lukel97 Jul 31, 2025
f11ad61
Use isa<VPPhi>
lukel97 Jul 31, 2025
77f1e7f
Address comments
lukel97 Jul 31, 2025
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4 changes: 2 additions & 2 deletions llvm/lib/Transforms/Vectorize/VPlanVerifier.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -80,8 +80,8 @@ bool VPlanVerifier::verifyPhiRecipes(const VPBasicBlock *VPBB) {
NumActiveLaneMaskPhiRecipes++;

if (IsHeaderVPBB && !isa<VPHeaderPHIRecipe, VPWidenPHIRecipe>(*RecipeI) &&
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@fhahn fhahn Jul 31, 2025

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Suggested change
if (IsHeaderVPBB && !isa<VPHeaderPHIRecipe, VPWidenPHIRecipe>(*RecipeI) &&
if (IsHeaderVPBB && !isa<VPHeaderPHIRecipe, VPWidenPHIRecipe, VPPhi>(*RecipeI) &&

This can just use VPPhi I think.

!isa<VPInstruction>(*RecipeI) &&
cast<VPInstruction>(RecipeI)->getOpcode() == Instruction::PHI) {
!(isa<VPInstruction>(*RecipeI) &&
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@david-arm david-arm Jul 31, 2025

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Looking at the definition of isPhi it seems like we're missing tests where we have a VPPredInstPHIRecipe in the header VPBB, since that seems to be the only one (besides VPInstructions) where isPhi would return true and isa<VPHeaderPHIRecipe, VPWidenPHIRecipe>(*RecipeI) would return false.

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@david-arm david-arm Jul 31, 2025

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But looking at VPPredInstPHIRecipe it seems unlikely to be in the header, right? So perhaps there is no way to write a test case that proves this was broken.

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@lukel97 lukel97 Jul 31, 2025

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I think a VPIRPhi, i.e a VPIRInstruction with a PHI opcode should also be caught by this, I've added a test case for it in c170996

cast<VPInstruction>(RecipeI)->getOpcode() == Instruction::PHI)) {
errs() << "Found non-header PHI recipe in header VPBB";
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
errs() << ": ";
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