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[LLVM][CostModel][AArch64] Remove magic numbers from f16 vector compares. #135795

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Merged
merged 2 commits into from
Apr 22, 2025
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[LLVM][CostModel][AArch64] Remove magic numbers from f16 vector compares. #135795

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b7cfa4a
[LLVM][CostModel][AArch64] Remove magic numbers from f16 vector compa…
paulwalker-arm Apr 15, 2025
b0a5cdb
Fix typo Promte->Promote.
paulwalker-arm Apr 17, 2025
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32 changes: 28 additions & 4 deletions llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4236,10 +4236,34 @@ InstructionCost AArch64TTIImpl::getCmpSelInstrCost(
}

if (isa<FixedVectorType>(ValTy) && ISD == ISD::SETCC) {
auto LT = getTypeLegalizationCost(ValTy);
// Cost v4f16 FCmp without FP16 support via converting to v4f32 and back.
if (LT.second == MVT::v4f16 && !ST->hasFullFP16())
return LT.first * 4; // fcvtl + fcvtl + fcmp + xtn
Type *ValScalarTy = ValTy->getScalarType();
if ((ValScalarTy->isHalfTy() && !ST->hasFullFP16()) ||
ValScalarTy->isBFloatTy()) {
auto *ValVTy = cast<FixedVectorType>(ValTy);

// FIXME: We currently scalarise these.
if (ValVTy->getNumElements() > 4)
return BaseT::getCmpSelInstrCost(Opcode, ValTy, CondTy, VecPred,
CostKind, Op1Info, Op2Info, I);

// Without dedicated instructions we promote [b]f16 compares to f32.
auto *PromotedTy =
VectorType::get(Type::getFloatTy(ValTy->getContext()), ValVTy);

InstructionCost Cost = 0;
// Promote operands to float vectors.
Cost += 2 * getCastInstrCost(Instruction::FPExt, PromotedTy, ValTy,
TTI::CastContextHint::None, CostKind);
// Compare float vectors.
Cost += getCmpSelInstrCost(Opcode, PromotedTy, CondTy, VecPred, CostKind,
Op1Info, Op2Info);
// During codegen we'll truncate the vector result from i32 to i16.
Cost +=
getCastInstrCost(Instruction::Trunc, VectorType::getInteger(ValVTy),
VectorType::getInteger(PromotedTy),
TTI::CastContextHint::None, CostKind);
return Cost;
}
}

// Treat the icmp in icmp(and, 0) as free, as we can make use of ands.
Expand Down
16 changes: 8 additions & 8 deletions llvm/test/Analysis/CostModel/AArch64/vector-select.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -168,7 +168,7 @@ define <2 x double> @v2f64_select_ogt(<2 x double> %a, <2 x double> %b, <2 x dou

define <4 x bfloat> @v4bf16_select_ogt(<4 x bfloat> %a, <4 x bfloat> %b, <4 x bfloat> %c) {
; COST-LABEL: 'v4bf16_select_ogt'
; COST-NEXT: Cost Model: Found costs of 1 for: %cmp.1 = fcmp ogt <4 x bfloat> %a, %b
; COST-NEXT: Cost Model: Found costs of RThru:4 CodeSize:1 Lat:1 SizeLat:1 for: %cmp.1 = fcmp ogt <4 x bfloat> %a, %b
; COST-NEXT: Cost Model: Found costs of RThru:10 CodeSize:1 Lat:1 SizeLat:1 for: %s.1 = select <4 x i1> %cmp.1, <4 x bfloat> %a, <4 x bfloat> %c
; COST-NEXT: Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret <4 x bfloat> %s.1
;
Expand Down Expand Up @@ -255,7 +255,7 @@ define <2 x double> @v2f64_select_oge(<2 x double> %a, <2 x double> %b, <2 x dou

define <4 x bfloat> @v4bf16_select_oge(<4 x bfloat> %a, <4 x bfloat> %b, <4 x bfloat> %c) {
; COST-LABEL: 'v4bf16_select_oge'
; COST-NEXT: Cost Model: Found costs of 1 for: %cmp.1 = fcmp oge <4 x bfloat> %a, %b
; COST-NEXT: Cost Model: Found costs of RThru:4 CodeSize:1 Lat:1 SizeLat:1 for: %cmp.1 = fcmp oge <4 x bfloat> %a, %b
; COST-NEXT: Cost Model: Found costs of RThru:10 CodeSize:1 Lat:1 SizeLat:1 for: %s.1 = select <4 x i1> %cmp.1, <4 x bfloat> %a, <4 x bfloat> %c
; COST-NEXT: Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret <4 x bfloat> %s.1
;
Expand Down Expand Up @@ -342,7 +342,7 @@ define <2 x double> @v2f64_select_olt(<2 x double> %a, <2 x double> %b, <2 x dou

define <4 x bfloat> @v4bf16_select_olt(<4 x bfloat> %a, <4 x bfloat> %b, <4 x bfloat> %c) {
; COST-LABEL: 'v4bf16_select_olt'
; COST-NEXT: Cost Model: Found costs of 1 for: %cmp.1 = fcmp olt <4 x bfloat> %a, %b
; COST-NEXT: Cost Model: Found costs of RThru:4 CodeSize:1 Lat:1 SizeLat:1 for: %cmp.1 = fcmp olt <4 x bfloat> %a, %b
; COST-NEXT: Cost Model: Found costs of RThru:10 CodeSize:1 Lat:1 SizeLat:1 for: %s.1 = select <4 x i1> %cmp.1, <4 x bfloat> %a, <4 x bfloat> %c
; COST-NEXT: Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret <4 x bfloat> %s.1
;
Expand Down Expand Up @@ -429,7 +429,7 @@ define <2 x double> @v2f64_select_ole(<2 x double> %a, <2 x double> %b, <2 x dou

define <4 x bfloat> @v4bf16_select_ole(<4 x bfloat> %a, <4 x bfloat> %b, <4 x bfloat> %c) {
; COST-LABEL: 'v4bf16_select_ole'
; COST-NEXT: Cost Model: Found costs of 1 for: %cmp.1 = fcmp ole <4 x bfloat> %a, %b
; COST-NEXT: Cost Model: Found costs of RThru:4 CodeSize:1 Lat:1 SizeLat:1 for: %cmp.1 = fcmp ole <4 x bfloat> %a, %b
; COST-NEXT: Cost Model: Found costs of RThru:10 CodeSize:1 Lat:1 SizeLat:1 for: %s.1 = select <4 x i1> %cmp.1, <4 x bfloat> %a, <4 x bfloat> %c
; COST-NEXT: Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret <4 x bfloat> %s.1
;
Expand Down Expand Up @@ -516,7 +516,7 @@ define <2 x double> @v2f64_select_oeq(<2 x double> %a, <2 x double> %b, <2 x dou

define <4 x bfloat> @v4bf16_select_oeq(<4 x bfloat> %a, <4 x bfloat> %b, <4 x bfloat> %c) {
; COST-LABEL: 'v4bf16_select_oeq'
; COST-NEXT: Cost Model: Found costs of 1 for: %cmp.1 = fcmp oeq <4 x bfloat> %a, %b
; COST-NEXT: Cost Model: Found costs of RThru:4 CodeSize:1 Lat:1 SizeLat:1 for: %cmp.1 = fcmp oeq <4 x bfloat> %a, %b
; COST-NEXT: Cost Model: Found costs of RThru:10 CodeSize:1 Lat:1 SizeLat:1 for: %s.1 = select <4 x i1> %cmp.1, <4 x bfloat> %a, <4 x bfloat> %c
; COST-NEXT: Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret <4 x bfloat> %s.1
;
Expand Down Expand Up @@ -603,7 +603,7 @@ define <2 x double> @v2f64_select_one(<2 x double> %a, <2 x double> %b, <2 x dou

define <4 x bfloat> @v4bf16_select_one(<4 x bfloat> %a, <4 x bfloat> %b, <4 x bfloat> %c) {
; COST-LABEL: 'v4bf16_select_one'
; COST-NEXT: Cost Model: Found costs of 1 for: %cmp.1 = fcmp one <4 x bfloat> %a, %b
; COST-NEXT: Cost Model: Found costs of RThru:4 CodeSize:1 Lat:1 SizeLat:1 for: %cmp.1 = fcmp one <4 x bfloat> %a, %b
; COST-NEXT: Cost Model: Found costs of RThru:10 CodeSize:1 Lat:1 SizeLat:1 for: %s.1 = select <4 x i1> %cmp.1, <4 x bfloat> %a, <4 x bfloat> %c
; COST-NEXT: Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret <4 x bfloat> %s.1
;
Expand Down Expand Up @@ -690,7 +690,7 @@ define <2 x double> @v2f64_select_une(<2 x double> %a, <2 x double> %b, <2 x dou

define <4 x bfloat> @v4bf16_select_une(<4 x bfloat> %a, <4 x bfloat> %b, <4 x bfloat> %c) {
; COST-LABEL: 'v4bf16_select_une'
; COST-NEXT: Cost Model: Found costs of 1 for: %cmp.1 = fcmp une <4 x bfloat> %a, %b
; COST-NEXT: Cost Model: Found costs of RThru:4 CodeSize:1 Lat:1 SizeLat:1 for: %cmp.1 = fcmp une <4 x bfloat> %a, %b
; COST-NEXT: Cost Model: Found costs of RThru:10 CodeSize:1 Lat:1 SizeLat:1 for: %s.1 = select <4 x i1> %cmp.1, <4 x bfloat> %a, <4 x bfloat> %c
; COST-NEXT: Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret <4 x bfloat> %s.1
;
Expand Down Expand Up @@ -777,7 +777,7 @@ define <2 x double> @v2f64_select_ord(<2 x double> %a, <2 x double> %b, <2 x dou

define <4 x bfloat> @v4bf16_select_ord(<4 x bfloat> %a, <4 x bfloat> %b, <4 x bfloat> %c) {
; COST-LABEL: 'v4bf16_select_ord'
; COST-NEXT: Cost Model: Found costs of 1 for: %cmp.1 = fcmp ord <4 x bfloat> %a, %b
; COST-NEXT: Cost Model: Found costs of RThru:4 CodeSize:1 Lat:1 SizeLat:1 for: %cmp.1 = fcmp ord <4 x bfloat> %a, %b
; COST-NEXT: Cost Model: Found costs of RThru:10 CodeSize:1 Lat:1 SizeLat:1 for: %s.1 = select <4 x i1> %cmp.1, <4 x bfloat> %a, <4 x bfloat> %c
; COST-NEXT: Cost Model: Found costs of RThru:0 CodeSize:1 Lat:1 SizeLat:1 for: ret <4 x bfloat> %s.1
;
Expand Down
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