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[VectorCombine] foldShuffleOfShuffles - relax one-use of inner shuffles #116062

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Merged
merged 2 commits into from
Nov 13, 2024
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[VectorCombine] foldShuffleOfShuffles - relax one-use of inner shuffles #116062

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9245d08
[VectorCombine] foldShuffleOfShuffles - relax one-use of inner shuffles
RKSimon Nov 13, 2024
cde783a
Avoid repeated getOperand() calls.
RKSimon Nov 13, 2024
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23 changes: 15 additions & 8 deletions llvm/lib/Transforms/Vectorize/VectorCombine.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1721,11 +1721,11 @@ bool VectorCombine::foldShuffleOfShuffles(Instruction &I) {
Value *V0, *V1;
UndefValue *U0, *U1;
ArrayRef<int> OuterMask, InnerMask0, InnerMask1;
if (!match(&I, m_Shuffle(m_OneUse(m_Shuffle(m_Value(V0), m_UndefValue(U0),
m_Mask(InnerMask0))),
m_OneUse(m_Shuffle(m_Value(V1), m_UndefValue(U1),
m_Mask(InnerMask1))),
m_Mask(OuterMask))))
if (!match(&I,
m_Shuffle(
m_Shuffle(m_Value(V0), m_UndefValue(U0), m_Mask(InnerMask0)),
m_Shuffle(m_Value(V1), m_UndefValue(U1), m_Mask(InnerMask1)),
m_Mask(OuterMask))))
return false;

auto *ShufI0 = dyn_cast<Instruction>(I.getOperand(0));
Expand Down Expand Up @@ -1769,17 +1769,24 @@ bool VectorCombine::foldShuffleOfShuffles(Instruction &I) {
// Try to merge the shuffles if the new shuffle is not costly.
TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput;

InstructionCost OldCost =
InstructionCost InnerCost0 =
TTI.getShuffleCost(TargetTransformInfo::SK_PermuteSingleSrc, ShuffleSrcTy,
InnerMask0, CostKind, 0, nullptr, {V0, U0}, ShufI0) +
InnerMask0, CostKind, 0, nullptr, {V0, U0}, ShufI0);
InstructionCost InnerCost1 =
TTI.getShuffleCost(TargetTransformInfo::SK_PermuteSingleSrc, ShuffleSrcTy,
InnerMask1, CostKind, 0, nullptr, {V1, U1}, ShufI1) +
InnerMask1, CostKind, 0, nullptr, {V1, U1}, ShufI1);
InstructionCost OuterCost =
TTI.getShuffleCost(TargetTransformInfo::SK_PermuteTwoSrc, ShuffleImmTy,
OuterMask, CostKind, 0, nullptr, {ShufI0, ShufI1}, &I);
InstructionCost OldCost = InnerCost0 + InnerCost1 + OuterCost;

InstructionCost NewCost =
TTI.getShuffleCost(TargetTransformInfo::SK_PermuteTwoSrc, ShuffleSrcTy,
NewMask, CostKind, 0, nullptr, {V0, V1});
if (!ShufI0->hasOneUse())
NewCost += InnerCost0;
if (!ShufI1->hasOneUse())
NewCost += InnerCost1;

LLVM_DEBUG(dbgs() << "Found a shuffle feeding two shuffles: " << I
<< "\n OldCost: " << OldCost << " vs NewCost: " << NewCost
Expand Down
10 changes: 3 additions & 7 deletions llvm/test/Transforms/VectorCombine/AArch64/shuffletoidentity.ll
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Expand Up @@ -1080,11 +1080,9 @@ define <16 x i64> @operandbundles(<4 x i64> %a, <4 x i64> %b, <4 x i64> %c) {

define <8 x i8> @operandbundles_first(<8 x i8> %a) {
; CHECK-LABEL: @operandbundles_first(
; CHECK-NEXT: [[AB:%.*]] = shufflevector <8 x i8> [[A:%.*]], <8 x i8> poison, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
; CHECK-NEXT: [[AT:%.*]] = shufflevector <8 x i8> [[A]], <8 x i8> poison, <4 x i32> <i32 7, i32 6, i32 5, i32 4>
; CHECK-NEXT: [[AT:%.*]] = shufflevector <8 x i8> [[A:%.*]], <8 x i8> poison, <4 x i32> <i32 7, i32 6, i32 5, i32 4>
; CHECK-NEXT: [[ABT:%.*]] = call <4 x i8> @llvm.abs.v4i8(<4 x i8> [[AT]], i1 false) [ "jl_roots"(ptr addrspace(10) null, ptr addrspace(10) null) ]
; CHECK-NEXT: [[TMP1:%.*]] = shufflevector <4 x i8> [[AT]], <4 x i8> [[AB]], <8 x i32> <i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
; CHECK-NEXT: [[R:%.*]] = call <8 x i8> @llvm.abs.v8i8(<8 x i8> [[TMP1]], i1 false)
; CHECK-NEXT: [[R:%.*]] = call <8 x i8> @llvm.abs.v8i8(<8 x i8> [[A]], i1 false)
; CHECK-NEXT: ret <8 x i8> [[R]]
;
%ab = shufflevector <8 x i8> %a, <8 x i8> poison, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
Expand All @@ -1098,10 +1096,8 @@ define <8 x i8> @operandbundles_first(<8 x i8> %a) {
define <8 x i8> @operandbundles_second(<8 x i8> %a) {
; CHECK-LABEL: @operandbundles_second(
; CHECK-NEXT: [[AB:%.*]] = shufflevector <8 x i8> [[A:%.*]], <8 x i8> poison, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
; CHECK-NEXT: [[AT:%.*]] = shufflevector <8 x i8> [[A]], <8 x i8> poison, <4 x i32> <i32 7, i32 6, i32 5, i32 4>
; CHECK-NEXT: [[ABB:%.*]] = call <4 x i8> @llvm.abs.v4i8(<4 x i8> [[AB]], i1 false) [ "jl_roots"(ptr addrspace(10) null, ptr addrspace(10) null) ]
; CHECK-NEXT: [[TMP1:%.*]] = shufflevector <4 x i8> [[AT]], <4 x i8> [[AB]], <8 x i32> <i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
; CHECK-NEXT: [[R:%.*]] = call <8 x i8> @llvm.abs.v8i8(<8 x i8> [[TMP1]], i1 false)
; CHECK-NEXT: [[R:%.*]] = call <8 x i8> @llvm.abs.v8i8(<8 x i8> [[A]], i1 false)
; CHECK-NEXT: ret <8 x i8> [[R]]
;
%ab = shufflevector <8 x i8> %a, <8 x i8> poison, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
Expand Down
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