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[X86] getShuffleCost - when splitting shuffles, if a whole vector sou…
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…rce is just copied we should treat this as free. (#120561)

If the shuffle split results in referencing a single legalised whole vector (i.e. no permutation), then this can be treated as free.

We already do something similar for broadcasts / whole subvector insertion + extraction - its purely an issue for register allocation.
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@RKSimon
RKSimon authored Dec 19, 2024
1 parent 89da344 commit 9bb1d03
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4 changes: 2 additions & 2 deletions llvm/lib/Target/X86/X86TargetTransformInfo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1728,7 +1728,7 @@ InstructionCost X86TTIImpl::getShuffleCost(
// destination register is just a copy of the source register or the
// copy of the previous destination register (the cost is
// TTI::TCC_Basic). If the source register is just reused, the cost for
// this operation is 0.
// this operation is TTI::TCC_Free.
NumOfDests =
getTypeLegalizationCost(
FixedVectorType::get(BaseTp->getElementType(), Mask.size()))
Expand Down Expand Up @@ -1762,7 +1762,7 @@ InstructionCost X86TTIImpl::getShuffleCost(
if (SrcReg != DestReg &&
any_of(RegMask, [](int I) { return I != PoisonMaskElem; })) {
// Just a copy of the source register.
Cost += TTI::TCC_Basic;
Cost += TTI::TCC_Free;
}
PrevSrcReg = SrcReg;
PrevRegMask = RegMask;
Expand Down
28 changes: 14 additions & 14 deletions llvm/test/Analysis/CostModel/X86/reduction.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -61,7 +61,7 @@ define fastcc float @reduction_cost_float(<4 x float> %rdx) {

define fastcc i32 @reduction_cost_int(<8 x i32> %rdx) {
; SSE-LABEL: 'reduction_cost_int'
; SSE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf = shufflevector <8 x i32> %rdx, <8 x i32> undef, <8 x i32> <i32 4, i32 5, i32 6, i32 7, i32 poison, i32 poison, i32 poison, i32 poison>
; SSE-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %rdx.shuf = shufflevector <8 x i32> %rdx, <8 x i32> undef, <8 x i32> <i32 4, i32 5, i32 6, i32 7, i32 poison, i32 poison, i32 poison, i32 poison>
; SSE-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %bin.rdx = add <8 x i32> %rdx, %rdx.shuf
; SSE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf.2 = shufflevector <8 x i32> %bin.rdx, <8 x i32> undef, <8 x i32> <i32 2, i32 3, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison>
; SSE-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %bin.rdx.2 = add <8 x i32> %bin.rdx, %rdx.shuf.2
Expand Down Expand Up @@ -91,7 +91,7 @@ define fastcc i32 @reduction_cost_int(<8 x i32> %rdx) {
; AVX2-NEXT: Cost Model: Found an estimated cost of 0 for instruction: ret i32 %r
;
; SLM-LABEL: 'reduction_cost_int'
; SLM-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf = shufflevector <8 x i32> %rdx, <8 x i32> undef, <8 x i32> <i32 4, i32 5, i32 6, i32 7, i32 poison, i32 poison, i32 poison, i32 poison>
; SLM-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %rdx.shuf = shufflevector <8 x i32> %rdx, <8 x i32> undef, <8 x i32> <i32 4, i32 5, i32 6, i32 7, i32 poison, i32 poison, i32 poison, i32 poison>
; SLM-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %bin.rdx = add <8 x i32> %rdx, %rdx.shuf
; SLM-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf.2 = shufflevector <8 x i32> %bin.rdx, <8 x i32> undef, <8 x i32> <i32 2, i32 3, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison>
; SLM-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %bin.rdx.2 = add <8 x i32> %bin.rdx, %rdx.shuf.2
Expand Down Expand Up @@ -416,23 +416,23 @@ define fastcc float @no_pairwise_reduction4float(<4 x float> %rdx, float %f1) {

define fastcc double @no_pairwise_reduction4double(<4 x double> %rdx, double %f1) {
; SSE2-LABEL: 'no_pairwise_reduction4double'
; SSE2-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf = shufflevector <4 x double> %rdx, <4 x double> undef, <4 x i32> <i32 2, i32 3, i32 poison, i32 poison>
; SSE2-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %rdx.shuf = shufflevector <4 x double> %rdx, <4 x double> undef, <4 x i32> <i32 2, i32 3, i32 poison, i32 poison>
; SSE2-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %bin.rdx = fadd <4 x double> %rdx, %rdx.shuf
; SSE2-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf7 = shufflevector <4 x double> %bin.rdx, <4 x double> undef, <4 x i32> <i32 1, i32 poison, i32 poison, i32 poison>
; SSE2-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %bin.rdx8 = fadd <4 x double> %bin.rdx, %rdx.shuf7
; SSE2-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %r = extractelement <4 x double> %bin.rdx8, i32 0
; SSE2-NEXT: Cost Model: Found an estimated cost of 0 for instruction: ret double %r
;
; SSSE3-LABEL: 'no_pairwise_reduction4double'
; SSSE3-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf = shufflevector <4 x double> %rdx, <4 x double> undef, <4 x i32> <i32 2, i32 3, i32 poison, i32 poison>
; SSSE3-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %rdx.shuf = shufflevector <4 x double> %rdx, <4 x double> undef, <4 x i32> <i32 2, i32 3, i32 poison, i32 poison>
; SSSE3-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %bin.rdx = fadd <4 x double> %rdx, %rdx.shuf
; SSSE3-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf7 = shufflevector <4 x double> %bin.rdx, <4 x double> undef, <4 x i32> <i32 1, i32 poison, i32 poison, i32 poison>
; SSSE3-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %bin.rdx8 = fadd <4 x double> %bin.rdx, %rdx.shuf7
; SSSE3-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %r = extractelement <4 x double> %bin.rdx8, i32 0
; SSSE3-NEXT: Cost Model: Found an estimated cost of 0 for instruction: ret double %r
;
; SSE42-LABEL: 'no_pairwise_reduction4double'
; SSE42-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf = shufflevector <4 x double> %rdx, <4 x double> undef, <4 x i32> <i32 2, i32 3, i32 poison, i32 poison>
; SSE42-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %rdx.shuf = shufflevector <4 x double> %rdx, <4 x double> undef, <4 x i32> <i32 2, i32 3, i32 poison, i32 poison>
; SSE42-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %bin.rdx = fadd <4 x double> %rdx, %rdx.shuf
; SSE42-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf7 = shufflevector <4 x double> %bin.rdx, <4 x double> undef, <4 x i32> <i32 1, i32 poison, i32 poison, i32 poison>
; SSE42-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %bin.rdx8 = fadd <4 x double> %bin.rdx, %rdx.shuf7
Expand All @@ -456,7 +456,7 @@ define fastcc double @no_pairwise_reduction4double(<4 x double> %rdx, double %f1
; AVX2-NEXT: Cost Model: Found an estimated cost of 0 for instruction: ret double %r
;
; SLM-LABEL: 'no_pairwise_reduction4double'
; SLM-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf = shufflevector <4 x double> %rdx, <4 x double> undef, <4 x i32> <i32 2, i32 3, i32 poison, i32 poison>
; SLM-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %rdx.shuf = shufflevector <4 x double> %rdx, <4 x double> undef, <4 x i32> <i32 2, i32 3, i32 poison, i32 poison>
; SLM-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %bin.rdx = fadd <4 x double> %rdx, %rdx.shuf
; SLM-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf7 = shufflevector <4 x double> %bin.rdx, <4 x double> undef, <4 x i32> <i32 1, i32 poison, i32 poison, i32 poison>
; SLM-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %bin.rdx8 = fadd <4 x double> %bin.rdx, %rdx.shuf7
Expand All @@ -474,7 +474,7 @@ define fastcc double @no_pairwise_reduction4double(<4 x double> %rdx, double %f1

define fastcc float @no_pairwise_reduction8float(<8 x float> %rdx, float %f1) {
; SSE2-LABEL: 'no_pairwise_reduction8float'
; SSE2-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf3 = shufflevector <8 x float> %rdx, <8 x float> undef, <8 x i32> <i32 4, i32 5, i32 6, i32 7, i32 poison, i32 poison, i32 poison, i32 poison>
; SSE2-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %rdx.shuf3 = shufflevector <8 x float> %rdx, <8 x float> undef, <8 x i32> <i32 4, i32 5, i32 6, i32 7, i32 poison, i32 poison, i32 poison, i32 poison>
; SSE2-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %bin.rdx4 = fadd <8 x float> %rdx, %rdx.shuf3
; SSE2-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf = shufflevector <8 x float> %bin.rdx4, <8 x float> undef, <8 x i32> <i32 2, i32 3, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison>
; SSE2-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %bin.rdx = fadd <8 x float> %bin.rdx4, %rdx.shuf
Expand All @@ -484,7 +484,7 @@ define fastcc float @no_pairwise_reduction8float(<8 x float> %rdx, float %f1) {
; SSE2-NEXT: Cost Model: Found an estimated cost of 0 for instruction: ret float %r
;
; SSSE3-LABEL: 'no_pairwise_reduction8float'
; SSSE3-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf3 = shufflevector <8 x float> %rdx, <8 x float> undef, <8 x i32> <i32 4, i32 5, i32 6, i32 7, i32 poison, i32 poison, i32 poison, i32 poison>
; SSSE3-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %rdx.shuf3 = shufflevector <8 x float> %rdx, <8 x float> undef, <8 x i32> <i32 4, i32 5, i32 6, i32 7, i32 poison, i32 poison, i32 poison, i32 poison>
; SSSE3-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %bin.rdx4 = fadd <8 x float> %rdx, %rdx.shuf3
; SSSE3-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf = shufflevector <8 x float> %bin.rdx4, <8 x float> undef, <8 x i32> <i32 2, i32 3, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison>
; SSSE3-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %bin.rdx = fadd <8 x float> %bin.rdx4, %rdx.shuf
Expand All @@ -494,7 +494,7 @@ define fastcc float @no_pairwise_reduction8float(<8 x float> %rdx, float %f1) {
; SSSE3-NEXT: Cost Model: Found an estimated cost of 0 for instruction: ret float %r
;
; SSE42-LABEL: 'no_pairwise_reduction8float'
; SSE42-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf3 = shufflevector <8 x float> %rdx, <8 x float> undef, <8 x i32> <i32 4, i32 5, i32 6, i32 7, i32 poison, i32 poison, i32 poison, i32 poison>
; SSE42-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %rdx.shuf3 = shufflevector <8 x float> %rdx, <8 x float> undef, <8 x i32> <i32 4, i32 5, i32 6, i32 7, i32 poison, i32 poison, i32 poison, i32 poison>
; SSE42-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %bin.rdx4 = fadd <8 x float> %rdx, %rdx.shuf3
; SSE42-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf = shufflevector <8 x float> %bin.rdx4, <8 x float> undef, <8 x i32> <i32 2, i32 3, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison>
; SSE42-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %bin.rdx = fadd <8 x float> %bin.rdx4, %rdx.shuf
Expand Down Expand Up @@ -524,7 +524,7 @@ define fastcc float @no_pairwise_reduction8float(<8 x float> %rdx, float %f1) {
; AVX2-NEXT: Cost Model: Found an estimated cost of 0 for instruction: ret float %r
;
; SLM-LABEL: 'no_pairwise_reduction8float'
; SLM-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf3 = shufflevector <8 x float> %rdx, <8 x float> undef, <8 x i32> <i32 4, i32 5, i32 6, i32 7, i32 poison, i32 poison, i32 poison, i32 poison>
; SLM-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %rdx.shuf3 = shufflevector <8 x float> %rdx, <8 x float> undef, <8 x i32> <i32 4, i32 5, i32 6, i32 7, i32 poison, i32 poison, i32 poison, i32 poison>
; SLM-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %bin.rdx4 = fadd <8 x float> %rdx, %rdx.shuf3
; SLM-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf = shufflevector <8 x float> %bin.rdx4, <8 x float> undef, <8 x i32> <i32 2, i32 3, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison>
; SLM-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %bin.rdx = fadd <8 x float> %bin.rdx4, %rdx.shuf
Expand Down Expand Up @@ -592,7 +592,7 @@ define fastcc i32 @no_pairwise_reduction4i32(<4 x i32> %rdx, i32 %f1) {

define fastcc i64 @no_pairwise_reduction4i64(<4 x i64> %rdx, i64 %f1) {
; SSE-LABEL: 'no_pairwise_reduction4i64'
; SSE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf = shufflevector <4 x i64> %rdx, <4 x i64> undef, <4 x i32> <i32 2, i32 3, i32 poison, i32 poison>
; SSE-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %rdx.shuf = shufflevector <4 x i64> %rdx, <4 x i64> undef, <4 x i32> <i32 2, i32 3, i32 poison, i32 poison>
; SSE-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %bin.rdx = add <4 x i64> %rdx, %rdx.shuf
; SSE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf7 = shufflevector <4 x i64> %bin.rdx, <4 x i64> undef, <4 x i32> <i32 1, i32 poison, i32 poison, i32 poison>
; SSE-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %bin.rdx8 = add <4 x i64> %bin.rdx, %rdx.shuf7
Expand All @@ -616,7 +616,7 @@ define fastcc i64 @no_pairwise_reduction4i64(<4 x i64> %rdx, i64 %f1) {
; AVX2-NEXT: Cost Model: Found an estimated cost of 0 for instruction: ret i64 %r
;
; SLM-LABEL: 'no_pairwise_reduction4i64'
; SLM-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf = shufflevector <4 x i64> %rdx, <4 x i64> undef, <4 x i32> <i32 2, i32 3, i32 poison, i32 poison>
; SLM-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %rdx.shuf = shufflevector <4 x i64> %rdx, <4 x i64> undef, <4 x i32> <i32 2, i32 3, i32 poison, i32 poison>
; SLM-NEXT: Cost Model: Found an estimated cost of 8 for instruction: %bin.rdx = add <4 x i64> %rdx, %rdx.shuf
; SLM-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf7 = shufflevector <4 x i64> %bin.rdx, <4 x i64> undef, <4 x i32> <i32 1, i32 poison, i32 poison, i32 poison>
; SLM-NEXT: Cost Model: Found an estimated cost of 8 for instruction: %bin.rdx8 = add <4 x i64> %bin.rdx, %rdx.shuf7
Expand Down Expand Up @@ -696,7 +696,7 @@ define fastcc i16 @no_pairwise_reduction8i16(<8 x i16> %rdx, i16 %f1) {

define fastcc i32 @no_pairwise_reduction8i32(<8 x i32> %rdx, i32 %f1) {
; SSE-LABEL: 'no_pairwise_reduction8i32'
; SSE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf3 = shufflevector <8 x i32> %rdx, <8 x i32> undef, <8 x i32> <i32 4, i32 5, i32 6, i32 7, i32 poison, i32 poison, i32 poison, i32 poison>
; SSE-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %rdx.shuf3 = shufflevector <8 x i32> %rdx, <8 x i32> undef, <8 x i32> <i32 4, i32 5, i32 6, i32 7, i32 poison, i32 poison, i32 poison, i32 poison>
; SSE-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %bin.rdx4 = add <8 x i32> %rdx, %rdx.shuf3
; SSE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf = shufflevector <8 x i32> %bin.rdx4, <8 x i32> undef, <8 x i32> <i32 2, i32 3, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison>
; SSE-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %bin.rdx = add <8 x i32> %bin.rdx4, %rdx.shuf
Expand Down Expand Up @@ -726,7 +726,7 @@ define fastcc i32 @no_pairwise_reduction8i32(<8 x i32> %rdx, i32 %f1) {
; AVX2-NEXT: Cost Model: Found an estimated cost of 0 for instruction: ret i32 %r
;
; SLM-LABEL: 'no_pairwise_reduction8i32'
; SLM-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf3 = shufflevector <8 x i32> %rdx, <8 x i32> undef, <8 x i32> <i32 4, i32 5, i32 6, i32 7, i32 poison, i32 poison, i32 poison, i32 poison>
; SLM-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %rdx.shuf3 = shufflevector <8 x i32> %rdx, <8 x i32> undef, <8 x i32> <i32 4, i32 5, i32 6, i32 7, i32 poison, i32 poison, i32 poison, i32 poison>
; SLM-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %bin.rdx4 = add <8 x i32> %rdx, %rdx.shuf3
; SLM-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf = shufflevector <8 x i32> %bin.rdx4, <8 x i32> undef, <8 x i32> <i32 2, i32 3, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison>
; SLM-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %bin.rdx = add <8 x i32> %bin.rdx4, %rdx.shuf
Expand Down

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