https://github.com/arsenm updated
https://github.com/llvm/llvm-project/pull/131063
>From 45508d81234b41c9cf79f4031bfbbdae44026e21 Mon Sep 17 00:00:00 2001
From: Matt Arsenault <matthew.arsena...@amd.com>
Date: Thu, 13 Mar 2025 10:48:15 +0700
Subject: [PATCH] AMDGPU: Make fma_legacy intrinsic propagate poison
---
.../AMDGPU/AMDGPUInstCombineIntrinsic.cpp | 5 ++++
.../InstCombine/AMDGPU/fma_legacy.ll | 24 +++++++++++++++++++
2 files changed, 29 insertions(+)
diff --git a/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
b/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
index b92f1bdd6a801..0bbded6a3422a 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
@@ -1282,6 +1282,11 @@ GCNTTIImpl::instCombineIntrinsic(InstCombiner &IC,
IntrinsicInst &II) const {
Value *Op1 = II.getArgOperand(1);
Value *Op2 = II.getArgOperand(2);
+ for (Value *Src : {Op0, Op1, Op2}) {
+ 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/fma_legacy.ll
b/llvm/test/Transforms/InstCombine/AMDGPU/fma_legacy.ll
index 72bffe62fbb14..b2f851d6d56ed 100644
--- a/llvm/test/Transforms/InstCombine/AMDGPU/fma_legacy.ll
+++ b/llvm/test/Transforms/InstCombine/AMDGPU/fma_legacy.ll
@@ -105,6 +105,30 @@ define float @test_finite_assumed(float %x, float %y,
float %z) {
ret float %call
}
+define float @test_poison_x_y(float %x, float %y) {
+; CHECK-LABEL: @test_poison_x_y(
+; CHECK-NEXT: ret float poison
+;
+ %call = call float @llvm.amdgcn.fma.legacy(float poison, float %x, float %y)
+ ret float %call
+}
+
+define float @test_x_poison_y(float %x, float %y) {
+; CHECK-LABEL: @test_x_poison_y(
+; CHECK-NEXT: ret float poison
+;
+ %call = call float @llvm.amdgcn.fma.legacy(float %x, float poison, float %y)
+ ret float %call
+}
+
+define float @test_x_y_poison_y(float %x, float %y) {
+; CHECK-LABEL: @test_x_y_poison_y(
+; CHECK-NEXT: ret float poison
+;
+ %call = call float @llvm.amdgcn.fma.legacy(float %x, float %y, float poison)
+ ret float %call
+}
+
declare float @llvm.amdgcn.fma.legacy(float, float, float)
declare float @llvm.fabs.f32(float)
declare void @llvm.assume(i1 noundef)
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