[llvm] 81691d2 - [RISCV][TTI] Update cost and prevent exceed m8 for vector.extract.last.active (#188160)
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Thu Apr 2 01:49:10 PDT 2026
Author: Elvis Wang
Date: 2026-04-02T16:49:05+08:00
New Revision: 81691d23cd1895436bcf2bdbf1b92adf1dcb761e
URL: https://github.com/llvm/llvm-project/commit/81691d23cd1895436bcf2bdbf1b92adf1dcb761e
DIFF: https://github.com/llvm/llvm-project/commit/81691d23cd1895436bcf2bdbf1b92adf1dcb761e.diff
LOG: [RISCV][TTI] Update cost and prevent exceed m8 for vector.extract.last.active (#188160)
This patch contains two parts.
1. Update costs reflect to the codegen changes. This is not that
accurate since the step vector can use smaller type if there is a
vscale_range attribute. But we cannot get that in the type-based query
in TTI.
2. Return invalid cost for the vector.extract.last.active that needs
vector split for the step vector. But currently this is not handled
correctly and will hit the assertion.
For not blocking the FindLast reduction in LV
(https://github.com/llvm/llvm-project/pull/184931). We should land this
first and fix the SelectionDAG for vector.extract.last.active lowering.
Added:
Modified:
llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
llvm/test/Analysis/CostModel/RISCV/extract-last-active.ll
Removed:
################################################################################
diff --git a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
index 21f9a73967ac1..fd762f35124b5 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
@@ -1733,12 +1733,19 @@ RISCVTTIImpl::getIntrinsicInstrCost(const IntrinsicCostAttributes &ICA,
// Find a suitable type for a stepvector.
ConstantRange VScaleRange(APInt(64, 1), APInt::getZero(64));
unsigned EltWidth = getTLI()->getBitWidthForCttzElements(
- MaskLT.second.getScalarType(), MaskTy->getElementCount(),
+ TLI->getVectorIdxTy(getDataLayout()), MaskTy->getElementCount(),
/*ZeroIsPoison=*/true, &VScaleRange);
EltWidth = std::max(EltWidth, MaskTy->getScalarSizeInBits());
Type *StepTy = Type::getIntNTy(MaskTy->getContext(), EltWidth);
auto *StepVecTy = VectorType::get(StepTy, ValTy->getElementCount());
auto StepLT = getTypeLegalizationCost(StepVecTy);
+
+ // Currently expandVectorFindLastActive cannot handle step vector split.
+ // So return invalid when the type needs split.
+ // FIXME: Remove this if expandVectorFindLastActive supports split vector.
+ if (StepLT.first > 1)
+ return InstructionCost::getInvalid();
+
InstructionCost Cost = 0;
unsigned Opcodes[] = {RISCV::VID_V, RISCV::VREDMAXU_VS, RISCV::VMV_X_S};
diff --git a/llvm/test/Analysis/CostModel/RISCV/extract-last-active.ll b/llvm/test/Analysis/CostModel/RISCV/extract-last-active.ll
index d6b00a8bf8a79..84f18e3df9015 100644
--- a/llvm/test/Analysis/CostModel/RISCV/extract-last-active.ll
+++ b/llvm/test/Analysis/CostModel/RISCV/extract-last-active.ll
@@ -11,14 +11,14 @@ define void @extractions() {
; CHECK-NEXT: Cost Model: Found an estimated cost of 9 for instruction: %v8bf16 = call bfloat @llvm.experimental.vector.extract.last.active.v8bf16(<8 x bfloat> poison, <8 x i1> poison, bfloat poison)
; CHECK-NEXT: Cost Model: Found an estimated cost of 8 for instruction: %v4f32 = call float @llvm.experimental.vector.extract.last.active.v4f32(<4 x float> poison, <4 x i1> poison, float poison)
; CHECK-NEXT: Cost Model: Found an estimated cost of 7 for instruction: %v2f64 = call double @llvm.experimental.vector.extract.last.active.v2f64(<2 x double> poison, <2 x i1> poison, double poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 13 for instruction: %nxv16i8 = call i8 @llvm.experimental.vector.extract.last.active.nxv16i8(<vscale x 16 x i8> poison, <vscale x 16 x i1> poison, i8 poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 11 for instruction: %nxv8i16 = call i16 @llvm.experimental.vector.extract.last.active.nxv8i16(<vscale x 8 x i16> poison, <vscale x 8 x i1> poison, i16 poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 10 for instruction: %nxv4i32 = call i32 @llvm.experimental.vector.extract.last.active.nxv4i32(<vscale x 4 x i32> poison, <vscale x 4 x i1> poison, i32 poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 9 for instruction: %nxv2i64 = call i64 @llvm.experimental.vector.extract.last.active.nxv2i64(<vscale x 2 x i64> poison, <vscale x 2 x i1> poison, i64 poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 11 for instruction: %nxv8f16 = call half @llvm.experimental.vector.extract.last.active.nxv8f16(<vscale x 8 x half> poison, <vscale x 8 x i1> poison, half poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 11 for instruction: %nxv8bf16 = call bfloat @llvm.experimental.vector.extract.last.active.nxv8bf16(<vscale x 8 x bfloat> poison, <vscale x 8 x i1> poison, bfloat poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 10 for instruction: %nxv4f32 = call float @llvm.experimental.vector.extract.last.active.nxv4f32(<vscale x 4 x float> poison, <vscale x 4 x i1> poison, float poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 9 for instruction: %nxv2f64 = call double @llvm.experimental.vector.extract.last.active.nxv2f64(<vscale x 2 x double> poison, <vscale x 2 x i1> poison, double poison)
+; CHECK-NEXT: Cost Model: Invalid cost for instruction: %nxv16i8 = call i8 @llvm.experimental.vector.extract.last.active.nxv16i8(<vscale x 16 x i8> poison, <vscale x 16 x i1> poison, i8 poison)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 18 for instruction: %nxv8i16 = call i16 @llvm.experimental.vector.extract.last.active.nxv8i16(<vscale x 8 x i16> poison, <vscale x 8 x i1> poison, i16 poison)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 13 for instruction: %nxv4i32 = call i32 @llvm.experimental.vector.extract.last.active.nxv4i32(<vscale x 4 x i32> poison, <vscale x 4 x i1> poison, i32 poison)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 10 for instruction: %nxv2i64 = call i64 @llvm.experimental.vector.extract.last.active.nxv2i64(<vscale x 2 x i64> poison, <vscale x 2 x i1> poison, i64 poison)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 18 for instruction: %nxv8f16 = call half @llvm.experimental.vector.extract.last.active.nxv8f16(<vscale x 8 x half> poison, <vscale x 8 x i1> poison, half poison)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 18 for instruction: %nxv8bf16 = call bfloat @llvm.experimental.vector.extract.last.active.nxv8bf16(<vscale x 8 x bfloat> poison, <vscale x 8 x i1> poison, bfloat poison)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 13 for instruction: %nxv4f32 = call float @llvm.experimental.vector.extract.last.active.nxv4f32(<vscale x 4 x float> poison, <vscale x 4 x i1> poison, float poison)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 10 for instruction: %nxv2f64 = call double @llvm.experimental.vector.extract.last.active.nxv2f64(<vscale x 2 x double> poison, <vscale x 2 x i1> poison, double poison)
; CHECK-NEXT: Cost Model: Found an estimated cost of 13 for instruction: %v32i8 = call i8 @llvm.experimental.vector.extract.last.active.v32i8(<32 x i8> poison, <32 x i1> poison, i8 poison)
; CHECK-NEXT: Cost Model: Found an estimated cost of 11 for instruction: %v16i16 = call i16 @llvm.experimental.vector.extract.last.active.v16i16(<16 x i16> poison, <16 x i1> poison, i16 poison)
; CHECK-NEXT: Cost Model: Found an estimated cost of 10 for instruction: %v8i32 = call i32 @llvm.experimental.vector.extract.last.active.v8i32(<8 x i32> poison, <8 x i1> poison, i32 poison)
@@ -27,14 +27,14 @@ define void @extractions() {
; CHECK-NEXT: Cost Model: Found an estimated cost of 11 for instruction: %v16bf16 = call bfloat @llvm.experimental.vector.extract.last.active.v16bf16(<16 x bfloat> poison, <16 x i1> poison, bfloat poison)
; CHECK-NEXT: Cost Model: Found an estimated cost of 10 for instruction: %v8f32 = call float @llvm.experimental.vector.extract.last.active.v8f32(<8 x float> poison, <8 x i1> poison, float poison)
; CHECK-NEXT: Cost Model: Found an estimated cost of 9 for instruction: %v4f64 = call double @llvm.experimental.vector.extract.last.active.v4f64(<4 x double> poison, <4 x i1> poison, double poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 18 for instruction: %nxv32i8 = call i8 @llvm.experimental.vector.extract.last.active.nxv32i8(<vscale x 32 x i8> poison, <vscale x 32 x i1> poison, i8 poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 15 for instruction: %nxv16i16 = call i16 @llvm.experimental.vector.extract.last.active.nxv16i16(<vscale x 16 x i16> poison, <vscale x 16 x i1> poison, i16 poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 13 for instruction: %nxv8i32 = call i32 @llvm.experimental.vector.extract.last.active.nxv8i32(<vscale x 8 x i32> poison, <vscale x 8 x i1> poison, i32 poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 12 for instruction: %nxv4i64 = call i64 @llvm.experimental.vector.extract.last.active.nxv4i64(<vscale x 4 x i64> poison, <vscale x 4 x i1> poison, i64 poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 15 for instruction: %nxv16f16 = call half @llvm.experimental.vector.extract.last.active.nxv16f16(<vscale x 16 x half> poison, <vscale x 16 x i1> poison, half poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 15 for instruction: %nxv16bf16 = call bfloat @llvm.experimental.vector.extract.last.active.nxv16bf16(<vscale x 16 x bfloat> poison, <vscale x 16 x i1> poison, bfloat poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 13 for instruction: %nxv8f32 = call float @llvm.experimental.vector.extract.last.active.nxv8f32(<vscale x 8 x float> poison, <vscale x 8 x i1> poison, float poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 12 for instruction: %nxv4f64 = call double @llvm.experimental.vector.extract.last.active.nxv4f64(<vscale x 4 x double> poison, <vscale x 4 x i1> poison, double poison)
+; CHECK-NEXT: Cost Model: Invalid cost for instruction: %nxv32i8 = call i8 @llvm.experimental.vector.extract.last.active.nxv32i8(<vscale x 32 x i8> poison, <vscale x 32 x i1> poison, i8 poison)
+; CHECK-NEXT: Cost Model: Invalid cost for instruction: %nxv16i16 = call i16 @llvm.experimental.vector.extract.last.active.nxv16i16(<vscale x 16 x i16> poison, <vscale x 16 x i1> poison, i16 poison)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 20 for instruction: %nxv8i32 = call i32 @llvm.experimental.vector.extract.last.active.nxv8i32(<vscale x 8 x i32> poison, <vscale x 8 x i1> poison, i32 poison)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 15 for instruction: %nxv4i64 = call i64 @llvm.experimental.vector.extract.last.active.nxv4i64(<vscale x 4 x i64> poison, <vscale x 4 x i1> poison, i64 poison)
+; CHECK-NEXT: Cost Model: Invalid cost for instruction: %nxv16f16 = call half @llvm.experimental.vector.extract.last.active.nxv16f16(<vscale x 16 x half> poison, <vscale x 16 x i1> poison, half poison)
+; CHECK-NEXT: Cost Model: Invalid cost for instruction: %nxv16bf16 = call bfloat @llvm.experimental.vector.extract.last.active.nxv16bf16(<vscale x 16 x bfloat> poison, <vscale x 16 x i1> poison, bfloat poison)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 20 for instruction: %nxv8f32 = call float @llvm.experimental.vector.extract.last.active.nxv8f32(<vscale x 8 x float> poison, <vscale x 8 x i1> poison, float poison)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 15 for instruction: %nxv4f64 = call double @llvm.experimental.vector.extract.last.active.nxv4f64(<vscale x 4 x double> poison, <vscale x 4 x i1> poison, double poison)
; CHECK-NEXT: Cost Model: Found an estimated cost of 9 for instruction: %v8i8 = call i8 @llvm.experimental.vector.extract.last.active.v8i8(<8 x i8> poison, <8 x i1> poison, i8 poison)
; CHECK-NEXT: Cost Model: Found an estimated cost of 8 for instruction: %v4i16 = call i16 @llvm.experimental.vector.extract.last.active.v4i16(<4 x i16> poison, <4 x i1> poison, i16 poison)
; CHECK-NEXT: Cost Model: Found an estimated cost of 7 for instruction: %v2i32 = call i32 @llvm.experimental.vector.extract.last.active.v2i32(<2 x i32> poison, <2 x i1> poison, i32 poison)
@@ -43,13 +43,13 @@ define void @extractions() {
; CHECK-NEXT: Cost Model: Found an estimated cost of 8 for instruction: %v4bf16 = call bfloat @llvm.experimental.vector.extract.last.active.v4bf16(<4 x bfloat> poison, <4 x i1> poison, bfloat poison)
; CHECK-NEXT: Cost Model: Found an estimated cost of 7 for instruction: %v2f32 = call float @llvm.experimental.vector.extract.last.active.v2f32(<2 x float> poison, <2 x i1> poison, float poison)
; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v1f64 = call double @llvm.experimental.vector.extract.last.active.v1f64(<1 x double> poison, <1 x i1> poison, double poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 10 for instruction: %nxv8i8 = call i8 @llvm.experimental.vector.extract.last.active.nxv8i8(<vscale x 8 x i8> poison, <vscale x 8 x i1> poison, i8 poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 9 for instruction: %nxv4i16 = call i16 @llvm.experimental.vector.extract.last.active.nxv4i16(<vscale x 4 x i16> poison, <vscale x 4 x i1> poison, i16 poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 8 for instruction: %nxv2i32 = call i32 @llvm.experimental.vector.extract.last.active.nxv2i32(<vscale x 2 x i32> poison, <vscale x 2 x i1> poison, i32 poison)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 17 for instruction: %nxv8i8 = call i8 @llvm.experimental.vector.extract.last.active.nxv8i8(<vscale x 8 x i8> poison, <vscale x 8 x i1> poison, i8 poison)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 12 for instruction: %nxv4i16 = call i16 @llvm.experimental.vector.extract.last.active.nxv4i16(<vscale x 4 x i16> poison, <vscale x 4 x i1> poison, i16 poison)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 9 for instruction: %nxv2i32 = call i32 @llvm.experimental.vector.extract.last.active.nxv2i32(<vscale x 2 x i32> poison, <vscale x 2 x i1> poison, i32 poison)
; CHECK-NEXT: Cost Model: Found an estimated cost of 7 for instruction: %nxv1i64 = call i64 @llvm.experimental.vector.extract.last.active.nxv1i64(<vscale x 1 x i64> poison, <vscale x 1 x i1> poison, i64 poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 9 for instruction: %nxv4f16 = call half @llvm.experimental.vector.extract.last.active.nxv4f16(<vscale x 4 x half> poison, <vscale x 4 x i1> poison, half poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 9 for instruction: %nxv4bf16 = call bfloat @llvm.experimental.vector.extract.last.active.nxv4bf16(<vscale x 4 x bfloat> poison, <vscale x 4 x i1> poison, bfloat poison)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 8 for instruction: %nxv2f32 = call float @llvm.experimental.vector.extract.last.active.nxv2f32(<vscale x 2 x float> poison, <vscale x 2 x i1> poison, float poison)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 12 for instruction: %nxv4f16 = call half @llvm.experimental.vector.extract.last.active.nxv4f16(<vscale x 4 x half> poison, <vscale x 4 x i1> poison, half poison)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 12 for instruction: %nxv4bf16 = call bfloat @llvm.experimental.vector.extract.last.active.nxv4bf16(<vscale x 4 x bfloat> poison, <vscale x 4 x i1> poison, bfloat poison)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 9 for instruction: %nxv2f32 = call float @llvm.experimental.vector.extract.last.active.nxv2f32(<vscale x 2 x float> poison, <vscale x 2 x i1> poison, float poison)
; CHECK-NEXT: Cost Model: Found an estimated cost of 7 for instruction: %nxv1f64 = call double @llvm.experimental.vector.extract.last.active.nxv1f64(<vscale x 1 x double> poison, <vscale x 1 x i1> poison, double poison)
; CHECK-NEXT: Cost Model: Found an estimated cost of 0 for instruction: ret void
;
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