AMDGPU: Make fmul_legacy intrinsic propagate poison #131062
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arsenm
added
backend:AMDGPU
llvm:instcombine
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This was referenced Mar 13, 2025
arsenm
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jayfoad,
Pierre-vh,
pravinjagtap,
rampitec and
shiltian
|
@llvm/pr-subscribers-backend-amdgpu Author: Matt Arsenault (arsenm) ChangesFull diff: https://github.com/llvm/llvm-project/pull/131062.diff 2 Files Affected:
diff --git a/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp b/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
index 083fa2a730fff..ba4e6e530fe56 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
@@ -1255,6 +1255,11 @@ GCNTTIImpl::instCombineIntrinsic(InstCombiner &IC, IntrinsicInst &II) const {
Value *Op0 = II.getArgOperand(0);
Value *Op1 = II.getArgOperand(1);
+ for (Value *Src : {Op0, Op1}) {
+ if (isa<PoisonValue>(Src))
+ return IC.replaceInstUsesWith(II, Src);
+ }
+
// The legacy behaviour is that multiplying +/-0.0 by anything, even NaN or
// infinity, gives +0.0.
// TODO: Move to InstSimplify?
diff --git a/llvm/test/Transforms/InstCombine/AMDGPU/fmul_legacy.ll b/llvm/test/Transforms/InstCombine/AMDGPU/fmul_legacy.ll
index d58470d6b12ad..899b611b929d1 100644
--- a/llvm/test/Transforms/InstCombine/AMDGPU/fmul_legacy.ll
+++ b/llvm/test/Transforms/InstCombine/AMDGPU/fmul_legacy.ll
@@ -75,6 +75,22 @@ define float @test_finite_assumed(float %x, float %y) {
ret float %call
}
+define float @test_poison_var(float %x) {
+; CHECK-LABEL: @test_poison_var(
+; CHECK-NEXT: ret float poison
+;
+ %call = call float @llvm.amdgcn.fmul.legacy(float poison, float %x)
+ ret float %call
+}
+
+define float @test_var_poison(float %x) {
+; CHECK-LABEL: @test_var_poison(
+; CHECK-NEXT: ret float poison
+;
+ %call = call float @llvm.amdgcn.fmul.legacy(float %x, float poison)
+ ret float %call
+}
+
declare float @llvm.amdgcn.fmul.legacy(float, float)
declare float @llvm.fabs.f32(float)
declare void @llvm.assume(i1 noundef)
|
|
@llvm/pr-subscribers-llvm-transforms Author: Matt Arsenault (arsenm) ChangesFull diff: https://github.com/llvm/llvm-project/pull/131062.diff 2 Files Affected:
diff --git a/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp b/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
index 083fa2a730fff..ba4e6e530fe56 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
@@ -1255,6 +1255,11 @@ GCNTTIImpl::instCombineIntrinsic(InstCombiner &IC, IntrinsicInst &II) const {
Value *Op0 = II.getArgOperand(0);
Value *Op1 = II.getArgOperand(1);
+ for (Value *Src : {Op0, Op1}) {
+ if (isa<PoisonValue>(Src))
+ return IC.replaceInstUsesWith(II, Src);
+ }
+
// The legacy behaviour is that multiplying +/-0.0 by anything, even NaN or
// infinity, gives +0.0.
// TODO: Move to InstSimplify?
diff --git a/llvm/test/Transforms/InstCombine/AMDGPU/fmul_legacy.ll b/llvm/test/Transforms/InstCombine/AMDGPU/fmul_legacy.ll
index d58470d6b12ad..899b611b929d1 100644
--- a/llvm/test/Transforms/InstCombine/AMDGPU/fmul_legacy.ll
+++ b/llvm/test/Transforms/InstCombine/AMDGPU/fmul_legacy.ll
@@ -75,6 +75,22 @@ define float @test_finite_assumed(float %x, float %y) {
ret float %call
}
+define float @test_poison_var(float %x) {
+; CHECK-LABEL: @test_poison_var(
+; CHECK-NEXT: ret float poison
+;
+ %call = call float @llvm.amdgcn.fmul.legacy(float poison, float %x)
+ ret float %call
+}
+
+define float @test_var_poison(float %x) {
+; CHECK-LABEL: @test_var_poison(
+; CHECK-NEXT: ret float poison
+;
+ %call = call float @llvm.amdgcn.fmul.legacy(float %x, float poison)
+ ret float %call
+}
+
declare float @llvm.amdgcn.fmul.legacy(float, float)
declare float @llvm.fabs.f32(float)
declare void @llvm.assume(i1 noundef)
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