[llvm-branch-commits] [llvm] AMDGPU: Make fmed3 intrinsic propagate poison (PR #131060)

[Matt Arsenault via llvm-branch-commits]

https://github.com/arsenm updated https://github.com/llvm/llvm-project/pull/131060

>From 4b8aef2f108aeb71dc1ffb29392cbb1a4548a576 Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault at amd.com>
Date: Thu, 13 Mar 2025 10:37:11 +0700
Subject: [PATCH] AMDGPU: Make fmed3 intrinsic propagate poison

---
 .../AMDGPU/AMDGPUInstCombineIntrinsic.cpp     |  5 ++++
 .../InstCombine/AMDGPU/amdgcn-intrinsics.ll   | 24 +++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp b/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
index e1ab33c399b0b..02977a61efb55 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
@@ -827,6 +827,11 @@ GCNTTIImpl::instCombineIntrinsic(InstCombiner &IC, IntrinsicInst &II) const {
     Value *Src1 = II.getArgOperand(1);
     Value *Src2 = II.getArgOperand(2);
 
+    for (Value *Src : {Src0, Src1, Src2}) {
+      if (isa<PoisonValue>(Src))
+        return IC.replaceInstUsesWith(II, Src);
+    }
+
     // Checking for NaN before canonicalization provides better fidelity when
     // mapping other operations onto fmed3 since the order of operands is
     // unchanged.
diff --git a/llvm/test/Transforms/InstCombine/AMDGPU/amdgcn-intrinsics.ll b/llvm/test/Transforms/InstCombine/AMDGPU/amdgcn-intrinsics.ll
index 2f64e4d15f357..af5c66165e67e 100644
--- a/llvm/test/Transforms/InstCombine/AMDGPU/amdgcn-intrinsics.ll
+++ b/llvm/test/Transforms/InstCombine/AMDGPU/amdgcn-intrinsics.ll
@@ -2121,6 +2121,30 @@ define float @fmed3_0_1_undef_f32() {
   ret float %med
 }
 
+define float @fmed3_poison_x_y_f32(float %x, float %y) {
+; CHECK-LABEL: @fmed3_poison_x_y_f32(
+; CHECK-NEXT:    ret float poison
+;
+  %med3 = call float @llvm.amdgcn.fmed3.f32(float poison, float %x, float %y)
+  ret float %med3
+}
+
+define float @fmed3_x_poison_y_f32(float %x, float %y) {
+; CHECK-LABEL: @fmed3_x_poison_y_f32(
+; CHECK-NEXT:    ret float poison
+;
+  %med3 = call float @llvm.amdgcn.fmed3.f32(float %x, float poison, float %y)
+  ret float %med3
+}
+
+define float @fmed3_x_y_poison_f32(float %x, float %y) {
+; CHECK-LABEL: @fmed3_x_y_poison_f32(
+; CHECK-NEXT:    ret float poison
+;
+  %med3 = call float @llvm.amdgcn.fmed3.f32(float %x, float %y, float poison)
+  ret float %med3
+}
+
 ; --------------------------------------------------------------------
 ; llvm.amdgcn.icmp
 ; --------------------------------------------------------------------