[llvm] [X86] canCreateUndefOrPoisonForTargetNode/isGuaranteedNotToBeUndefOrPoisonForTargetNode - add X86ISD::INSERTPS handling (PR #161234)

[Simon Pilgrim via llvm-commits]

https://github.com/RKSimon created https://github.com/llvm/llvm-project/pull/161234

X86ISD::INSERTPS shuffles can't create undef/poison itself, allowing us to fold freeze(insertps(x,y,i)) -> insertps(freeze(x),freeze(y),i)

>From 73177d580f88ddafea174a62be6edcfafb5e862a Mon Sep 17 00:00:00 2001
From: Simon Pilgrim <llvm-dev at redking.me.uk>
Date: Mon, 29 Sep 2025 18:07:52 +0100
Subject: [PATCH] [X86]
 canCreateUndefOrPoisonForTargetNode/isGuaranteedNotToBeUndefOrPoisonForTargetNode
 - add X86ISD::INSERTPS handling

X86ISD::INSERTPS shuffles can't create undef/poison itself, allowing us to fold freeze(insertps(x,y,i)) -> insertps(freeze(x),freeze(y),i)
---
 llvm/lib/Target/X86/X86ISelLowering.cpp                 | 2 ++
 llvm/test/CodeGen/X86/vector-shuffle-combining-sse41.ll | 5 +----
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 292eab77e2002..cd04ff5bc7ef4 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -45169,6 +45169,7 @@ bool X86TargetLowering::isGuaranteedNotToBeUndefOrPoisonForTargetNode(
   case X86ISD::Wrapper:
   case X86ISD::WrapperRIP:
     return true;
+  case X86ISD::INSERTPS:
   case X86ISD::BLENDI:
   case X86ISD::PSHUFB:
   case X86ISD::PSHUFD:
@@ -45239,6 +45240,7 @@ bool X86TargetLowering::canCreateUndefOrPoisonForTargetNode(
   case X86ISD::BLENDV:
     return false;
   // SSE target shuffles.
+  case X86ISD::INSERTPS:
   case X86ISD::PSHUFB:
   case X86ISD::PSHUFD:
   case X86ISD::UNPCKL:
diff --git a/llvm/test/CodeGen/X86/vector-shuffle-combining-sse41.ll b/llvm/test/CodeGen/X86/vector-shuffle-combining-sse41.ll
index bec33492bbf1e..3590c4d027be7 100644
--- a/llvm/test/CodeGen/X86/vector-shuffle-combining-sse41.ll
+++ b/llvm/test/CodeGen/X86/vector-shuffle-combining-sse41.ll
@@ -62,15 +62,12 @@ define <4 x i32> @combine_blend_of_permutes_v4i32(<2 x i64> %a0, <2 x i64> %a1)
 define <4 x float> @freeze_insertps(<4 x float> %a0, <4 x float> %a1) {
 ; SSE-LABEL: freeze_insertps:
 ; SSE:       # %bb.0:
-; SSE-NEXT:    insertps {{.*#+}} xmm0 = xmm0[0],xmm1[0],xmm0[2,3]
-; SSE-NEXT:    insertps {{.*#+}} xmm1 = xmm0[1],xmm1[1,2,3]
 ; SSE-NEXT:    movaps %xmm1, %xmm0
 ; SSE-NEXT:    retq
 ;
 ; AVX-LABEL: freeze_insertps:
 ; AVX:       # %bb.0:
-; AVX-NEXT:    vinsertps {{.*#+}} xmm0 = xmm0[0],xmm1[0],xmm0[2,3]
-; AVX-NEXT:    vinsertps {{.*#+}} xmm0 = xmm0[1],xmm1[1,2,3]
+; AVX-NEXT:    vmovaps %xmm1, %xmm0
 ; AVX-NEXT:    retq
   %s0 = call <4 x float> @llvm.x86.sse41.insertps(<4 x float> %a0, <4 x float> %a1, i8 16)
   %f0 = freeze <4 x float> %s0