[llvm] AMDGPU: Make frexp_exp and frexp_mant intrinsics propagate poison (PR #130915)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm updated https://github.com/llvm/llvm-project/pull/130915

>From 12ab535d96c1067140c028fd1328940fd2406a72 Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault at amd.com>
Date: Wed, 12 Mar 2025 14:11:51 +0700
Subject: [PATCH] AMDGPU: Make frexp_exp and frexp_mant intrinsics propagate
 poison

---
 .../Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp |  3 +++
 .../InstCombine/AMDGPU/amdgcn-intrinsics.ll      | 16 ++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp b/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
index 5314738b2b8ac..bf53018439e9f 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
@@ -636,6 +636,9 @@ GCNTTIImpl::instCombineIntrinsic(InstCombiner &IC, IntrinsicInst &II) const {
       return IC.replaceInstUsesWith(II, ConstantInt::get(II.getType(), Exp));
     }
 
+    if (isa<PoisonValue>(Src))
+      return IC.replaceInstUsesWith(II, PoisonValue::get(II.getType()));
+
     if (isa<UndefValue>(Src)) {
       return IC.replaceInstUsesWith(II, UndefValue::get(II.getType()));
     }
diff --git a/llvm/test/Transforms/InstCombine/AMDGPU/amdgcn-intrinsics.ll b/llvm/test/Transforms/InstCombine/AMDGPU/amdgcn-intrinsics.ll
index fca3860240294..78606b1c869d1 100644
--- a/llvm/test/Transforms/InstCombine/AMDGPU/amdgcn-intrinsics.ll
+++ b/llvm/test/Transforms/InstCombine/AMDGPU/amdgcn-intrinsics.ll
@@ -274,6 +274,14 @@ declare float @llvm.amdgcn.frexp.mant.f32(float) nounwind readnone
 declare double @llvm.amdgcn.frexp.mant.f64(double) nounwind readnone
 
 
+define float @test_constant_fold_frexp_mant_f32_poison() nounwind {
+; CHECK-LABEL: @test_constant_fold_frexp_mant_f32_poison(
+; CHECK-NEXT:    ret float poison
+;
+  %val = call float @llvm.amdgcn.frexp.mant.f32(float poison)
+  ret float %val
+}
+
 define float @test_constant_fold_frexp_mant_f32_undef() nounwind {
 ; CHECK-LABEL: @test_constant_fold_frexp_mant_f32_undef(
 ; CHECK-NEXT:    ret float undef
@@ -442,6 +450,14 @@ define double @test_constant_fold_frexp_mant_f64_min_num() nounwind {
 declare i32 @llvm.amdgcn.frexp.exp.f32(float) nounwind readnone
 declare i32 @llvm.amdgcn.frexp.exp.f64(double) nounwind readnone
 
+define i32 @test_constant_fold_frexp_exp_f32_poison() nounwind {
+; CHECK-LABEL: @test_constant_fold_frexp_exp_f32_poison(
+; CHECK-NEXT:    ret i32 poison
+;
+  %val = call i32 @llvm.amdgcn.frexp.exp.f32(float poison)
+  ret i32 %val
+}
+
 define i32 @test_constant_fold_frexp_exp_f32_undef() nounwind {
 ; CHECK-LABEL: @test_constant_fold_frexp_exp_f32_undef(
 ; CHECK-NEXT:    ret i32 undef