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[AArch64] Reduce the cost of repeated sub-shuffle #139331

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May 16, 2025
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[AArch64] Reduce the cost of repeated sub-shuffle #139331

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23 changes: 18 additions & 5 deletions llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5479,6 +5479,8 @@ InstructionCost AArch64TTIImpl::getShuffleCost(
VectorType *NTp =
VectorType::get(Tp->getScalarType(), LT.second.getVectorElementCount());
InstructionCost Cost;
std::map<std::tuple<unsigned, unsigned, SmallVector<int>>, InstructionCost>
PreviousCosts;
for (unsigned N = 0; N < NumVecs; N++) {
SmallVector<int> NMask;
// Split the existing mask into chunks of size LTNumElts. Track the source
Expand Down Expand Up @@ -5515,15 +5517,26 @@ InstructionCost AArch64TTIImpl::getShuffleCost(
else
NMask.push_back(MaskElt % LTNumElts);
}
// Check if we have already generated this sub-shuffle, which means we
// will have already generated the output. For example a <16 x i32> splat
// will be the same sub-splat 4 times, which only needs to be generated
// once and reused.
auto Result =
PreviousCosts.insert({std::make_tuple(Source1, Source2, NMask), 0});
// Check if it was already in the map (already costed).
if (!Result.second)
continue;
// If the sub-mask has at most 2 input sub-vectors then re-cost it using
// getShuffleCost. If not then cost it using the worst case as the number
// of element moves into a new vector.
if (NumSources <= 2)
Cost += getShuffleCost(NumSources <= 1 ? TTI::SK_PermuteSingleSrc
InstructionCost NCost =
NumSources <= 2
? getShuffleCost(NumSources <= 1 ? TTI::SK_PermuteSingleSrc
: TTI::SK_PermuteTwoSrc,
NTp, NMask, CostKind, 0, nullptr, Args, CxtI);
else
Cost += LTNumElts;
NTp, NMask, CostKind, 0, nullptr, Args, CxtI)
: LTNumElts;
Result.first->second = NCost;
Cost += NCost;
}
return Cost;
}
Expand Down
32 changes: 16 additions & 16 deletions llvm/test/Analysis/CostModel/AArch64/div.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -123,27 +123,27 @@ define void @sdiv_uniform() {
; CHECK-LABEL: 'sdiv_uniform'
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V2i64_s = shufflevector <2 x i64> poison, <2 x i64> poison, <2 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:28 CodeSize:4 Lat:4 SizeLat:4 for: %V2i64 = sdiv <2 x i64> undef, %V2i64_s
; CHECK-NEXT: Cost Model: Found costs of 2 for: %V4i64_s = shufflevector <4 x i64> poison, <4 x i64> poison, <4 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V4i64_s = shufflevector <4 x i64> poison, <4 x i64> poison, <4 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:48 CodeSize:4 Lat:4 SizeLat:4 for: %V4i64 = sdiv <4 x i64> undef, %V4i64_s
; CHECK-NEXT: Cost Model: Found costs of 4 for: %V8i64_s = shufflevector <8 x i64> poison, <8 x i64> poison, <8 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V8i64_s = shufflevector <8 x i64> poison, <8 x i64> poison, <8 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:88 CodeSize:4 Lat:4 SizeLat:4 for: %V8i64 = sdiv <8 x i64> undef, %V8i64_s
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V2i32_s = shufflevector <2 x i32> poison, <2 x i32> poison, <2 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:28 CodeSize:4 Lat:4 SizeLat:4 for: %V2i32 = sdiv <2 x i32> undef, %V2i32_s
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V4i32_s = shufflevector <4 x i32> poison, <4 x i32> poison, <4 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:48 CodeSize:4 Lat:4 SizeLat:4 for: %V4i32 = sdiv <4 x i32> undef, %V4i32_s
; CHECK-NEXT: Cost Model: Found costs of 2 for: %V8i32_s = shufflevector <8 x i32> poison, <8 x i32> poison, <8 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V8i32_s = shufflevector <8 x i32> poison, <8 x i32> poison, <8 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:88 CodeSize:4 Lat:4 SizeLat:4 for: %V8i32 = sdiv <8 x i32> undef, %V8i32_s
; CHECK-NEXT: Cost Model: Found costs of 4 for: %V16i32_s = shufflevector <16 x i32> poison, <16 x i32> poison, <16 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V16i32_s = shufflevector <16 x i32> poison, <16 x i32> poison, <16 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:168 CodeSize:4 Lat:4 SizeLat:4 for: %V16i32 = sdiv <16 x i32> undef, %V16i32_s
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V2i16_s = shufflevector <2 x i16> poison, <2 x i16> poison, <2 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:28 CodeSize:4 Lat:4 SizeLat:4 for: %V2i16 = sdiv <2 x i16> undef, %V2i16_s
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V4i16_s = shufflevector <4 x i16> poison, <4 x i16> poison, <4 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:48 CodeSize:4 Lat:4 SizeLat:4 for: %V4i16 = sdiv <4 x i16> undef, %V4i16_s
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V8i16_s = shufflevector <8 x i16> poison, <8 x i16> poison, <8 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:88 CodeSize:4 Lat:4 SizeLat:4 for: %V8i16 = sdiv <8 x i16> undef, %V8i16_s
; CHECK-NEXT: Cost Model: Found costs of 2 for: %V16i16_s = shufflevector <16 x i16> poison, <16 x i16> poison, <16 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V16i16_s = shufflevector <16 x i16> poison, <16 x i16> poison, <16 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:168 CodeSize:4 Lat:4 SizeLat:4 for: %V16i16 = sdiv <16 x i16> undef, %V16i16_s
; CHECK-NEXT: Cost Model: Found costs of 4 for: %V32i16_s = shufflevector <32 x i16> poison, <32 x i16> poison, <32 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V32i16_s = shufflevector <32 x i16> poison, <32 x i16> poison, <32 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:328 CodeSize:4 Lat:4 SizeLat:4 for: %V32i16 = sdiv <32 x i16> undef, %V32i16_s
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V2i8_s = shufflevector <2 x i8> poison, <2 x i8> poison, <2 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:28 CodeSize:4 Lat:4 SizeLat:4 for: %V2i8 = sdiv <2 x i8> undef, %V2i8_s
Expand All @@ -153,9 +153,9 @@ define void @sdiv_uniform() {
; CHECK-NEXT: Cost Model: Found costs of RThru:88 CodeSize:4 Lat:4 SizeLat:4 for: %V8i8 = sdiv <8 x i8> undef, %V8i8_s
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V16i8_s = shufflevector <16 x i8> poison, <16 x i8> poison, <16 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:168 CodeSize:4 Lat:4 SizeLat:4 for: %V16i8 = sdiv <16 x i8> undef, %V16i8_s
; CHECK-NEXT: Cost Model: Found costs of 2 for: %V32i8_s = shufflevector <32 x i8> poison, <32 x i8> poison, <32 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V32i8_s = shufflevector <32 x i8> poison, <32 x i8> poison, <32 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:328 CodeSize:4 Lat:4 SizeLat:4 for: %V32i8 = sdiv <32 x i8> undef, %V32i8_s
; CHECK-NEXT: Cost Model: Found costs of 4 for: %V64i8_s = shufflevector <64 x i8> poison, <64 x i8> poison, <64 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V64i8_s = shufflevector <64 x i8> poison, <64 x i8> poison, <64 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:648 CodeSize:4 Lat:4 SizeLat:4 for: %V64i8 = sdiv <64 x i8> undef, %V64i8_s
; CHECK-NEXT: Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret void
;
Expand Down Expand Up @@ -206,27 +206,27 @@ define void @udiv_uniform() {
; CHECK-LABEL: 'udiv_uniform'
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V2i64_s = shufflevector <2 x i64> poison, <2 x i64> poison, <2 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:28 CodeSize:4 Lat:4 SizeLat:4 for: %V2i64 = udiv <2 x i64> undef, %V2i64_s
; CHECK-NEXT: Cost Model: Found costs of 2 for: %V4i64_s = shufflevector <4 x i64> poison, <4 x i64> poison, <4 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V4i64_s = shufflevector <4 x i64> poison, <4 x i64> poison, <4 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:48 CodeSize:4 Lat:4 SizeLat:4 for: %V4i64 = udiv <4 x i64> undef, %V4i64_s
; CHECK-NEXT: Cost Model: Found costs of 4 for: %V8i64_s = shufflevector <8 x i64> poison, <8 x i64> poison, <8 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V8i64_s = shufflevector <8 x i64> poison, <8 x i64> poison, <8 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:88 CodeSize:4 Lat:4 SizeLat:4 for: %V8i64 = udiv <8 x i64> undef, %V8i64_s
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V2i32_s = shufflevector <2 x i32> poison, <2 x i32> poison, <2 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:28 CodeSize:4 Lat:4 SizeLat:4 for: %V2i32 = udiv <2 x i32> undef, %V2i32_s
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V4i32_s = shufflevector <4 x i32> poison, <4 x i32> poison, <4 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:48 CodeSize:4 Lat:4 SizeLat:4 for: %V4i32 = udiv <4 x i32> undef, %V4i32_s
; CHECK-NEXT: Cost Model: Found costs of 2 for: %V8i32_s = shufflevector <8 x i32> poison, <8 x i32> poison, <8 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V8i32_s = shufflevector <8 x i32> poison, <8 x i32> poison, <8 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:88 CodeSize:4 Lat:4 SizeLat:4 for: %V8i32 = udiv <8 x i32> undef, %V8i32_s
; CHECK-NEXT: Cost Model: Found costs of 4 for: %V16i32_s = shufflevector <16 x i32> poison, <16 x i32> poison, <16 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V16i32_s = shufflevector <16 x i32> poison, <16 x i32> poison, <16 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:168 CodeSize:4 Lat:4 SizeLat:4 for: %V16i32 = udiv <16 x i32> undef, %V16i32_s
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V2i16_s = shufflevector <2 x i16> poison, <2 x i16> poison, <2 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:28 CodeSize:4 Lat:4 SizeLat:4 for: %V2i16 = udiv <2 x i16> undef, %V2i16_s
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V4i16_s = shufflevector <4 x i16> poison, <4 x i16> poison, <4 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:48 CodeSize:4 Lat:4 SizeLat:4 for: %V4i16 = udiv <4 x i16> undef, %V4i16_s
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V8i16_s = shufflevector <8 x i16> poison, <8 x i16> poison, <8 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:88 CodeSize:4 Lat:4 SizeLat:4 for: %V8i16 = udiv <8 x i16> undef, %V8i16_s
; CHECK-NEXT: Cost Model: Found costs of 2 for: %V16i16_s = shufflevector <16 x i16> poison, <16 x i16> poison, <16 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V16i16_s = shufflevector <16 x i16> poison, <16 x i16> poison, <16 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:168 CodeSize:4 Lat:4 SizeLat:4 for: %V16i16 = udiv <16 x i16> undef, %V16i16_s
; CHECK-NEXT: Cost Model: Found costs of 4 for: %V32i16_s = shufflevector <32 x i16> poison, <32 x i16> poison, <32 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V32i16_s = shufflevector <32 x i16> poison, <32 x i16> poison, <32 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:328 CodeSize:4 Lat:4 SizeLat:4 for: %V32i16 = udiv <32 x i16> undef, %V32i16_s
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V2i8_s = shufflevector <2 x i8> poison, <2 x i8> poison, <2 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:28 CodeSize:4 Lat:4 SizeLat:4 for: %V2i8 = udiv <2 x i8> undef, %V2i8_s
Expand All @@ -236,9 +236,9 @@ define void @udiv_uniform() {
; CHECK-NEXT: Cost Model: Found costs of RThru:88 CodeSize:4 Lat:4 SizeLat:4 for: %V8i8 = udiv <8 x i8> undef, %V8i8_s
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V16i8_s = shufflevector <16 x i8> poison, <16 x i8> poison, <16 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:168 CodeSize:4 Lat:4 SizeLat:4 for: %V16i8 = udiv <16 x i8> undef, %V16i8_s
; CHECK-NEXT: Cost Model: Found costs of 2 for: %V32i8_s = shufflevector <32 x i8> poison, <32 x i8> poison, <32 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V32i8_s = shufflevector <32 x i8> poison, <32 x i8> poison, <32 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:328 CodeSize:4 Lat:4 SizeLat:4 for: %V32i8 = udiv <32 x i8> undef, %V32i8_s
; CHECK-NEXT: Cost Model: Found costs of 4 for: %V64i8_s = shufflevector <64 x i8> poison, <64 x i8> poison, <64 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of 1 for: %V64i8_s = shufflevector <64 x i8> poison, <64 x i8> poison, <64 x i32> zeroinitializer
; CHECK-NEXT: Cost Model: Found costs of RThru:648 CodeSize:4 Lat:4 SizeLat:4 for: %V64i8 = udiv <64 x i8> undef, %V64i8_s
; CHECK-NEXT: Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret void
;
Expand Down
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