[llvm] e16f354 - [RISCV][TTI] Adjust the cost of `llvm.abs` intrinsic when `Zvabd` exists

[via llvm-commits]

Author: Pengcheng Wang
Date: 2026-02-09T15:50:14+08:00
New Revision: e16f35493c06d10682fca840786012266a591b42

URL: https://github.com/llvm/llvm-project/commit/e16f35493c06d10682fca840786012266a591b42
DIFF: https://github.com/llvm/llvm-project/commit/e16f35493c06d10682fca840786012266a591b42.diff

LOG: [RISCV][TTI] Adjust the cost of `llvm.abs` intrinsic when `Zvabd` exists

When `Zvabd` exists, `llvm.abs` is lowered to `vabs.v` so the cost
is 1.

Reviewers: mshockwave, topperc, lukel97, skachkov-sc, preames

Reviewed By: topperc

Pull Request: https://github.com/llvm/llvm-project/pull/180146

Added: 
    

Modified: 
    llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
    llvm/test/Analysis/CostModel/RISCV/abs.ll

Removed: 
    


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diff  --git a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
index dc4bf0784e2d1..e83ca19040555 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
@@ -1577,6 +1577,11 @@ RISCVTTIImpl::getIntrinsicInstrCost(const IntrinsicCostAttributes &ICA,
   case Intrinsic::abs: {
     auto LT = getTypeLegalizationCost(RetTy);
     if (ST->hasVInstructions() && LT.second.isVector()) {
+      // vabs.v v10, v8
+      if (ST->hasStdExtZvabd())
+        return LT.first *
+               getRISCVInstructionCost({RISCV::VABS_V}, LT.second, CostKind);
+
       // vrsub.vi v10, v8, 0
       // vmax.vv v8, v8, v10
       return LT.first *

diff  --git a/llvm/test/Analysis/CostModel/RISCV/abs.ll b/llvm/test/Analysis/CostModel/RISCV/abs.ll
index b1f93f3811580..80dd006c6ee77 100644
--- a/llvm/test/Analysis/CostModel/RISCV/abs.ll
+++ b/llvm/test/Analysis/CostModel/RISCV/abs.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py
 ; RUN: opt < %s -passes="print<cost-model>" 2>&1 -disable-output -S -mtriple=riscv64 -mattr=+v | FileCheck %s
+; RUN: opt < %s -passes="print<cost-model>" 2>&1 -disable-output -S -mtriple=riscv64 -mattr=+v,+experimental-zvabd | FileCheck %s --check-prefix=ZVABD
 ; Check that we don't crash querying costs when vectors are not enabled.
 ; RUN: opt -passes="print<cost-model>" 2>&1 -disable-output -mtriple=riscv64
 
@@ -38,6 +39,41 @@ define i32 @abs(i32 %arg) {
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %31 = call <vscale x 32 x i8> @llvm.abs.nxv32i8(<vscale x 32 x i8> undef, i1 false)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 16 for instruction: %32 = call <vscale x 64 x i8> @llvm.abs.nxv64i8(<vscale x 64 x i8> undef, i1 false)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: ret i32 undef
+;
+; ZVABD-LABEL: 'abs'
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %1 = call <2 x i64> @llvm.abs.v2i64(<2 x i64> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %2 = call <4 x i64> @llvm.abs.v4i64(<4 x i64> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %3 = call <8 x i64> @llvm.abs.v8i64(<8 x i64> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %4 = call <vscale x 2 x i64> @llvm.abs.nxv2i64(<vscale x 2 x i64> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %5 = call <vscale x 4 x i64> @llvm.abs.nxv4i64(<vscale x 4 x i64> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %6 = call <vscale x 8 x i64> @llvm.abs.nxv8i64(<vscale x 8 x i64> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %7 = call <2 x i32> @llvm.abs.v2i32(<2 x i32> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %8 = call <4 x i32> @llvm.abs.v4i32(<4 x i32> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %9 = call <8 x i32> @llvm.abs.v8i32(<8 x i32> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %10 = call <16 x i32> @llvm.abs.v16i32(<16 x i32> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %11 = call <vscale x 2 x i32> @llvm.abs.nxv2i32(<vscale x 2 x i32> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %12 = call <vscale x 4 x i32> @llvm.abs.nxv4i32(<vscale x 4 x i32> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %13 = call <vscale x 8 x i32> @llvm.abs.nxv8i32(<vscale x 8 x i32> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %14 = call <vscale x 16 x i32> @llvm.abs.nxv16i32(<vscale x 16 x i32> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %15 = call <2 x i16> @llvm.abs.v2i16(<2 x i16> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %16 = call <4 x i16> @llvm.abs.v4i16(<4 x i16> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %17 = call <8 x i16> @llvm.abs.v8i16(<8 x i16> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %18 = call <16 x i16> @llvm.abs.v16i16(<16 x i16> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %19 = call <32 x i16> @llvm.abs.v32i16(<32 x i16> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %20 = call <vscale x 2 x i16> @llvm.abs.nxv2i16(<vscale x 2 x i16> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %21 = call <vscale x 4 x i16> @llvm.abs.nxv4i16(<vscale x 4 x i16> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %22 = call <vscale x 8 x i16> @llvm.abs.nxv8i16(<vscale x 8 x i16> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %23 = call <vscale x 16 x i16> @llvm.abs.nxv16i16(<vscale x 16 x i16> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %24 = call <vscale x 32 x i16> @llvm.abs.nxv32i16(<vscale x 32 x i16> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %25 = call <8 x i8> @llvm.abs.v8i8(<8 x i8> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %26 = call <16 x i8> @llvm.abs.v16i8(<16 x i8> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %27 = call <32 x i8> @llvm.abs.v32i8(<32 x i8> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %28 = call <64 x i8> @llvm.abs.v64i8(<64 x i8> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %29 = call <vscale x 8 x i8> @llvm.abs.nxv8i8(<vscale x 8 x i8> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %30 = call <vscale x 16 x i8> @llvm.abs.nxv16i8(<vscale x 16 x i8> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %31 = call <vscale x 32 x i8> @llvm.abs.nxv32i8(<vscale x 32 x i8> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %32 = call <vscale x 64 x i8> @llvm.abs.nxv64i8(<vscale x 64 x i8> undef, i1 false)
+; ZVABD-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: ret i32 undef
 ;
   call <2 x i64> @llvm.abs.v2i64(<2 x i64> undef, i1 false)
   call <4 x i64> @llvm.abs.v4i64(<4 x i64> undef, i1 false)