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[VPlan] Allow VPWidenPHI in non-native path. NFC #118662

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[VPlan] Allow VPWidenPHI in non-native path. NFC #118662

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431d6d9
[LV] Allow VPWidenPHI in non-native path and copy DebugLoc
lukel97 Dec 4, 2024
cda41c6
Update comment
lukel97 Dec 4, 2024
f31878c
Rename fixNonInductionPHIs back
lukel97 Dec 4, 2024
69d4076
Update comments to clarify which parts can only be used in the vplan-…
lukel97 Dec 12, 2024
46ae402
Remove DebugLoc changes
lukel97 Jan 3, 2025
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3 changes: 1 addition & 2 deletions llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
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Expand Up @@ -2978,8 +2978,7 @@ LoopVectorizationCostModel::getVectorIntrinsicCost(CallInst *CI,

void InnerLoopVectorizer::fixVectorizedLoop(VPTransformState &State) {
// Fix widened non-induction PHIs by setting up the PHI operands.
if (EnableVPlanNativePath)
fixNonInductionPHIs(State);
fixNonInductionPHIs(State);

// Forget the original basic block.
PSE.getSE()->forgetLoop(OrigLoop);
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16 changes: 12 additions & 4 deletions llvm/lib/Transforms/Vectorize/VPlan.h
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Expand Up @@ -2287,10 +2287,16 @@ class VPWidenPHIRecipe : public VPSingleDefRecipe {
/// List of incoming blocks. Only used in the VPlan native path.
SmallVector<VPBasicBlock *, 2> IncomingBlocks;
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Maybe update the comments above re: usage in vplan native? Given this is now used in both paths, do these need delete or clarified?

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IncomingBlocks should still only be used in the vplan native path, so I've added more comments to the other methods that should only be called from it


/// Name to use for the generated IR instruction for the widened IV.
std::string Name;
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Maybe use SmallString or Twine?

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std::string seems to be what everything else in VPlan.h uses, and it doesn't look like Twine can be stored


public:
/// Create a new VPWidenPHIRecipe for \p Phi with start value \p Start.
VPWidenPHIRecipe(PHINode *Phi, VPValue *Start = nullptr)
: VPSingleDefRecipe(VPDef::VPWidenPHISC, ArrayRef<VPValue *>(), Phi) {
VPWidenPHIRecipe(PHINode *Phi, VPValue *Start = nullptr,
const Twine &Name = "vec.phi")
: VPSingleDefRecipe(VPDef::VPWidenPHISC, ArrayRef<VPValue *>(), Phi,
Phi->getDebugLoc()),
Name(Name.str()) {
if (Start)
addOperand(Start);
}
Expand All @@ -2312,13 +2318,15 @@ class VPWidenPHIRecipe : public VPSingleDefRecipe {
VPSlotTracker &SlotTracker) const override;
#endif

/// Adds a pair (\p IncomingV, \p IncomingBlock) to the phi.
/// Adds a pair (\p IncomingV, \p IncomingBlock) to the phi. Only used in the
/// VPlan native path.
void addIncoming(VPValue *IncomingV, VPBasicBlock *IncomingBlock) {
addOperand(IncomingV);
IncomingBlocks.push_back(IncomingBlock);
}

/// Returns the \p I th incoming VPBasicBlock.
/// Returns the \p I th incoming VPBasicBlock. Only used in the VPlan native
/// path.
VPBasicBlock *getIncomingBlock(unsigned I) { return IncomingBlocks[I]; }

/// Returns the \p I th incoming VPValue.
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7 changes: 4 additions & 3 deletions llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
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Expand Up @@ -3440,12 +3440,13 @@ void VPReductionPHIRecipe::print(raw_ostream &O, const Twine &Indent,
#endif

void VPWidenPHIRecipe::execute(VPTransformState &State) {
assert(EnableVPlanNativePath &&
"Non-native vplans are not expected to have VPWidenPHIRecipes.");
assert((EnableVPlanNativePath || IncomingBlocks.empty()) &&
"Non-native vplans are not expected to have VPWidenPHIRecipes with "
"incoming blocks.");

Value *Op0 = State.get(getOperand(0));
Type *VecTy = Op0->getType();
Value *VecPhi = State.Builder.CreatePHI(VecTy, 2, "vec.phi");
Value *VecPhi = State.Builder.CreatePHI(VecTy, 2, Name);
State.set(this, VecPhi);
}

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