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[VPlan] Pass backedge value directly to FOR and reduction phis (NFC).

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Pass backedge values directly to VPFirstOrderRecurrencePHIRecipe and
VPReductionPHIRecipe directly, as they must be provided and availbale.

Split off from https://github.com/llvm/llvm-project/pull/168291.
This commit is contained in:
Florian Hahn 2025-12-14 20:59:20 +00:00
parent 4cdec92827
commit bcbbe2c2bc
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GPG Key ID: C8B0D7090F9127E6
2 changed files with 23 additions and 21 deletions
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22
llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
View File

@ -8234,11 +8234,11 @@ VPRecipeBase *VPRecipeBuilder::tryToCreateWidenRecipe(VPSingleDefRecipe *R,
if ((Recipe = tryToOptimizeInductionPHI(PhiR)))
return Recipe;
VPHeaderPHIRecipe *PhiRecipe = nullptr;
assert((Legal->isReductionVariable(Phi) ||
Legal->isFixedOrderRecurrence(Phi)) &&
"can only widen reductions and fixed-order recurrences here");
VPValue *StartV = R->getOperand(0);
VPValue *BackedgeValue = R->getOperand(1);
if (Legal->isReductionVariable(Phi)) {
const RecurrenceDescriptor &RdxDesc = Legal->getRecurrenceDescriptor(Phi);
assert(RdxDesc.getRecurrenceStartValue() ==
@ -8250,22 +8250,20 @@ VPRecipeBase *VPRecipeBuilder::tryToCreateWidenRecipe(VPSingleDefRecipe *R,
unsigned ScaleFactor =
getScalingForReduction(RdxDesc.getLoopExitInstr()).value_or(1);
PhiRecipe = new VPReductionPHIRecipe(
Phi, RdxDesc.getRecurrenceKind(), *StartV,
return new VPReductionPHIRecipe(
Phi, RdxDesc.getRecurrenceKind(), *StartV, *BackedgeValue,
getReductionStyle(UseInLoopReduction, UseOrderedReductions,
ScaleFactor),
RdxDesc.hasUsesOutsideReductionChain());
} else {
// TODO: Currently fixed-order recurrences are modeled as chains of
// first-order recurrences. If there are no users of the intermediate
// recurrences in the chain, the fixed order recurrence should be modeled
// directly, enabling more efficient codegen.
PhiRecipe = new VPFirstOrderRecurrencePHIRecipe(Phi, *StartV);
}
// Add backedge value.
PhiRecipe->addOperand(R->getOperand(1));
return PhiRecipe;
// TODO: Currently fixed-order recurrences are modeled as chains of
// first-order recurrences. If there are no users of the intermediate
// recurrences in the chain, the fixed order recurrence should be modeled
// directly, enabling more efficient codegen.
return new VPFirstOrderRecurrencePHIRecipe(Phi, *StartV, *BackedgeValue);
}
assert(!R->isPhi() && "only VPPhi nodes expected at this point");
auto *VPI = cast<VPInstruction>(R);

22
llvm/lib/Transforms/Vectorize/VPlan.h
View File

@ -2366,14 +2366,17 @@ protected:
/// first operand of the recipe and the incoming value from the backedge is the
/// second operand.
struct VPFirstOrderRecurrencePHIRecipe : public VPHeaderPHIRecipe {
VPFirstOrderRecurrencePHIRecipe(PHINode *Phi, VPValue &Start)
: VPHeaderPHIRecipe(VPDef::VPFirstOrderRecurrencePHISC, Phi, &Start) {}
VPFirstOrderRecurrencePHIRecipe(PHINode *Phi, VPValue &Start,
VPValue &BackedgeValue)
: VPHeaderPHIRecipe(VPDef::VPFirstOrderRecurrencePHISC, Phi, &Start) {
addOperand(&BackedgeValue);
}
VP_CLASSOF_IMPL(VPDef::VPFirstOrderRecurrencePHISC)
VPFirstOrderRecurrencePHIRecipe *clone() override {
return new VPFirstOrderRecurrencePHIRecipe(
cast<PHINode>(getUnderlyingInstr()), *getOperand(0));
cast<PHINode>(getUnderlyingInstr()), *getOperand(0), *getOperand(1));
}
void execute(VPTransformState &State) override;
@ -2439,20 +2442,21 @@ class VPReductionPHIRecipe : public VPHeaderPHIRecipe,
public:
/// Create a new VPReductionPHIRecipe for the reduction \p Phi.
VPReductionPHIRecipe(PHINode *Phi, RecurKind Kind, VPValue &Start,
ReductionStyle Style,
VPValue &BackedgeValue, ReductionStyle Style,
bool HasUsesOutsideReductionChain = false)
: VPHeaderPHIRecipe(VPDef::VPReductionPHISC, Phi, &Start), Kind(Kind),
Style(Style),
HasUsesOutsideReductionChain(HasUsesOutsideReductionChain) {}
HasUsesOutsideReductionChain(HasUsesOutsideReductionChain) {
addOperand(&BackedgeValue);
}
~VPReductionPHIRecipe() override = default;
VPReductionPHIRecipe *clone() override {
auto *R = new VPReductionPHIRecipe(
return new VPReductionPHIRecipe(
dyn_cast_or_null<PHINode>(getUnderlyingValue()), getRecurrenceKind(),
*getOperand(0), Style, HasUsesOutsideReductionChain);
R->addOperand(getBackedgeValue());
return R;
*getOperand(0), *getBackedgeValue(), Style,
HasUsesOutsideReductionChain);
}
VP_CLASSOF_IMPL(VPDef::VPReductionPHISC)