[LV] Vectorize selecting last IV of min/max element. #141431
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| Original file line number | Diff line number | Diff line change | ||||
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@@ -815,3 +815,148 @@ bool VPlanTransforms::handleMaxMinNumReductions(VPlan &Plan) { | |||||
| MiddleTerm->setOperand(0, NewCond); | ||||||
| return true; | ||||||
| } | ||||||
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| bool VPlanTransforms::legalizeUnclassifiedPhis(VPlan &Plan) { | ||||||
| using namespace VPlanPatternMatch; | ||||||
| for (auto &PhiR : make_early_inc_range( | ||||||
| Plan.getVectorLoopRegion()->getEntryBasicBlock()->phis())) { | ||||||
| if (!isa<VPWidenPHIRecipe>(&PhiR)) | ||||||
| continue; | ||||||
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| // Check if PhiR is a min/max reduction that has a user inside the loop | ||||||
| // outside the min/max reduction chain. The other user must be the compare | ||||||
| // of a FindLastIV reduction chain. | ||||||
| auto *MinMaxPhiR = cast<VPWidenPHIRecipe>(&PhiR); | ||||||
| auto *MinMaxOp = dyn_cast_or_null<VPSingleDefRecipe>( | ||||||
| MinMaxPhiR->getOperand(1)->getDefiningRecipe()); | ||||||
| if (!MinMaxOp) | ||||||
| return false; | ||||||
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| // The incoming value must be a min/max instrinsic. | ||||||
| // TODO: Also handle the select variant. | ||||||
| Intrinsic::ID ID = Intrinsic::not_intrinsic; | ||||||
| if (auto *WideInt = dyn_cast<VPWidenIntrinsicRecipe>(MinMaxOp)) { | ||||||
| ID = WideInt->getVectorIntrinsicID(); | ||||||
| } else { | ||||||
| auto *RepR = dyn_cast<VPReplicateRecipe>(MinMaxOp); | ||||||
| if (!RepR || !isa<IntrinsicInst>(RepR->getUnderlyingInstr())) | ||||||
| return false; | ||||||
| ID = cast<IntrinsicInst>(RepR->getUnderlyingInstr())->getIntrinsicID(); | ||||||
| } | ||||||
| RecurKind RdxKind = RecurKind::None; | ||||||
| switch (ID) { | ||||||
| case Intrinsic::umax: | ||||||
| RdxKind = RecurKind::UMax; | ||||||
| break; | ||||||
| case Intrinsic::umin: | ||||||
| RdxKind = RecurKind::UMin; | ||||||
| break; | ||||||
| case Intrinsic::smax: | ||||||
| RdxKind = RecurKind::SMax; | ||||||
| break; | ||||||
| case Intrinsic::smin: | ||||||
| RdxKind = RecurKind::SMin; | ||||||
| break; | ||||||
| default: | ||||||
| return false; | ||||||
| } | ||||||
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| // The min/max intrinsic must use the phi and itself must only be used by | ||||||
| // the phi and a resume-phi in the scalar preheader. | ||||||
| if (MinMaxOp->getOperand(0) != MinMaxPhiR && | ||||||
| MinMaxOp->getOperand(1) != MinMaxPhiR) | ||||||
| return false; | ||||||
| if (MinMaxPhiR->getNumUsers() != 2 || | ||||||
|
There was a problem hiding this comment. Move the |
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| any_of(MinMaxOp->users(), [MinMaxPhiR, &Plan](VPUser *U) { | ||||||
| auto *Phi = dyn_cast<VPPhi>(U); | ||||||
| return MinMaxPhiR != U && | ||||||
| (!Phi || Phi->getParent() != Plan.getScalarPreheader()); | ||||||
| })) | ||||||
| return false; | ||||||
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| // One user of MinMaxPhiR is MinMaxOp, the other users must be a compare | ||||||
| // that's part of a FindLastIV chain. | ||||||
| auto MinMaxUsers = to_vector(MinMaxPhiR->users()); | ||||||
| auto *Cmp = dyn_cast<VPRecipeWithIRFlags>( | ||||||
| MinMaxUsers[0] == MinMaxOp ? MinMaxUsers[1] : MinMaxUsers[0]); | ||||||
|
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There was a problem hiding this comment. Should check the number of phi's users, like #141467 did: |
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| VPValue *CmpOpA; | ||||||
| VPValue *CmpOpB; | ||||||
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There was a problem hiding this comment. compress into one line, and choose the better name. |
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| if (!Cmp || Cmp->getNumUsers() != 1 || | ||||||
| !match(Cmp, m_Binary<Instruction::ICmp>(m_VPValue(CmpOpA), | ||||||
| m_VPValue(CmpOpB)))) | ||||||
| return false; | ||||||
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| // Normalize the predicate so MinMaxPhiR is on the right side. | ||||||
| CmpInst::Predicate Pred = Cmp->getPredicate(); | ||||||
| if (CmpOpA == MinMaxPhiR) | ||||||
| Pred = CmpInst::getSwappedPredicate(Pred); | ||||||
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| // Determine if the predicate is not strict. | ||||||
| bool IsNonStrictPred = ICmpInst::isLE(Pred) || ICmpInst::isGE(Pred); | ||||||
| // Account for a mis-match between RdxKind and the predicate. | ||||||
| switch (RdxKind) { | ||||||
| case RecurKind::UMin: | ||||||
| case RecurKind::SMin: | ||||||
| IsNonStrictPred |= ICmpInst::isGT(Pred); | ||||||
| break; | ||||||
| case RecurKind::UMax: | ||||||
| case RecurKind::SMax: | ||||||
| IsNonStrictPred |= ICmpInst::isLT(Pred); | ||||||
| break; | ||||||
| default: | ||||||
| llvm_unreachable("unsupported kind"); | ||||||
| } | ||||||
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| // TODO: Strict predicates need to find the first IV value for which the | ||||||
| // predicate holds, not the last. | ||||||
| if (Pred == CmpInst::ICMP_NE || !IsNonStrictPred) | ||||||
| return false; | ||||||
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| // Cmp must be used by the select of a FindLastIV chain. | ||||||
| VPValue *Sel = dyn_cast<VPSingleDefRecipe>(*Cmp->user_begin()); | ||||||
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| VPValue *IVOp, *FindIV; | ||||||
| if (!Sel || | ||||||
| !match(Sel, | ||||||
| m_Select(m_Specific(Cmp), m_VPValue(IVOp), m_VPValue(FindIV))) || | ||||||
| Sel->getNumUsers() != 2 || !isa<VPWidenIntOrFpInductionRecipe>(IVOp)) | ||||||
| return false; | ||||||
| auto *FindIVPhiR = dyn_cast<VPReductionPHIRecipe>(FindIV); | ||||||
| if (!FindIVPhiR || !RecurrenceDescriptor::isFindLastIVRecurrenceKind( | ||||||
| FindIVPhiR->getRecurrenceKind())) | ||||||
| return false; | ||||||
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| assert(!FindIVPhiR->isInLoop() && !FindIVPhiR->isOrdered() && | ||||||
| "cannot handle inloop/ordered reductions yet"); | ||||||
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| auto NewPhiR = new VPReductionPHIRecipe( | ||||||
| cast<PHINode>(MinMaxPhiR->getUnderlyingInstr()), RdxKind, | ||||||
| *MinMaxPhiR->getOperand(0), false, false, 1); | ||||||
| NewPhiR->insertBefore(MinMaxPhiR); | ||||||
| MinMaxPhiR->replaceAllUsesWith(NewPhiR); | ||||||
| NewPhiR->addOperand(MinMaxPhiR->getOperand(1)); | ||||||
| MinMaxPhiR->eraseFromParent(); | ||||||
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| // The reduction using MinMaxPhiR needs adjusting to compute the correct | ||||||
| // result: | ||||||
| // 1. We need to find the last IV for which the condition based on the | ||||||
| // min/max recurrence is true, | ||||||
| // 2. Compare the partial min/max reduction result to its final value and, | ||||||
| // 3. Select the lanes of the partial FindLastIV reductions which | ||||||
| // correspond to the lanes matching the min/max reduction result. | ||||||
| VPInstruction *FindIVResult = cast<VPInstruction>( | ||||||
| *(Sel->user_begin() + (*Sel->user_begin() == FindIVPhiR ? 1 : 0))); | ||||||
| VPBuilder B(FindIVResult); | ||||||
| VPInstruction *MinMaxResult = | ||||||
| B.createNaryOp(VPInstruction::ComputeReductionResult, | ||||||
| {NewPhiR, NewPhiR->getBackedgeValue()}, VPIRFlags(), {}); | ||||||
| NewPhiR->getBackedgeValue()->replaceUsesWithIf( | ||||||
| MinMaxResult, [](VPUser &U, unsigned) { return isa<VPPhi>(&U); }); | ||||||
| auto *FinalMinMaxCmp = B.createICmp( | ||||||
| CmpInst::ICMP_EQ, MinMaxResult->getOperand(1), MinMaxResult); | ||||||
| auto *FinalIVSelect = | ||||||
| B.createSelect(FinalMinMaxCmp, FindIVResult->getOperand(3), | ||||||
| FindIVResult->getOperand(2)); | ||||||
| FindIVResult->setOperand(3, FinalIVSelect); | ||||||
| } | ||||||
| return true; | ||||||
| } | ||||||
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MinMaxPhiR->getIncomingValue(1)