[llvm] [SelectionDAGBuilder] Only check VPCmp for NaNs in fp comparisons (PR #189749)

[via llvm-commits]

https://github.com/zGoldthorpe updated https://github.com/llvm/llvm-project/pull/189749

>From 99cbe29c85f89306a0a5fd8276116b1c0ea90a30 Mon Sep 17 00:00:00 2001
From: Zach Goldthorpe <Zach.Goldthorpe at amd.com>
Date: Tue, 31 Mar 2026 15:49:10 -0500
Subject: [PATCH 1/2] [SelectionDAGBuilder] Only check VPCmp for NaNs in fp
 comparisons

---
 .../lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 69ba9721401e1..06d1203ba0926 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -8859,8 +8859,6 @@ void SelectionDAGBuilder::visitVPCmp(const VPCmpIntrinsic &VPIntrin) {
 
   ISD::CondCode Condition;
   CmpInst::Predicate CondCode = VPIntrin.getPredicate();
-  bool IsFP = VPIntrin.getOperand(0)->getType()->isFPOrFPVectorTy();
-  Condition = IsFP ? getFCmpCondCode(CondCode) : getICmpCondCode(CondCode);
 
   SDValue Op1 = getValue(VPIntrin.getOperand(0));
   SDValue Op2 = getValue(VPIntrin.getOperand(1));
@@ -8872,10 +8870,16 @@ void SelectionDAGBuilder::visitVPCmp(const VPCmpIntrinsic &VPIntrin) {
          "Unexpected target EVL type");
   EVL = DAG.getNode(ISD::ZERO_EXTEND, DL, EVLParamVT, EVL);
 
+  if (VPIntrin.getOperand(0)->getType()->isFPOrFPVectorTy()) {
+    Condition = getFCmpCondCode(CondCode);
+    if (DAG.isKnownNeverNaN(Op1) && DAG.isKnownNeverNaN(Op2))
+      Condition = getFCmpCodeWithoutNaN(Condition);
+  } else {
+    Condition = getICmpCondCode(CondCode);
+  }
+
   EVT DestVT = DAG.getTargetLoweringInfo().getValueType(DAG.getDataLayout(),
                                                         VPIntrin.getType());
-  if (DAG.isKnownNeverNaN(Op1) && DAG.isKnownNeverNaN(Op2))
-    Condition = getFCmpCodeWithoutNaN(Condition);
   setValue(&VPIntrin,
            DAG.getSetCCVP(DL, DestVT, Op1, Op2, Condition, MaskOp, EVL));
 }

>From 6d8fbbaeec6d62b381762457845bc27c6b07aefd Mon Sep 17 00:00:00 2001
From: Zach Goldthorpe <Zach.Goldthorpe at amd.com>
Date: Wed, 1 Apr 2026 11:14:25 -0500
Subject: [PATCH 2/2] Replace `isKnownNeverNaN` with IR version.

---
 llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 06d1203ba0926..f58ffc3a720a8 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -8860,8 +8860,8 @@ void SelectionDAGBuilder::visitVPCmp(const VPCmpIntrinsic &VPIntrin) {
   ISD::CondCode Condition;
   CmpInst::Predicate CondCode = VPIntrin.getPredicate();
 
-  SDValue Op1 = getValue(VPIntrin.getOperand(0));
-  SDValue Op2 = getValue(VPIntrin.getOperand(1));
+  Value *Op1 = VPIntrin.getOperand(0);
+  Value *Op2 = VPIntrin.getOperand(1);
   // #2 is the condition code
   SDValue MaskOp = getValue(VPIntrin.getOperand(3));
   SDValue EVL = getValue(VPIntrin.getOperand(4));
@@ -8872,7 +8872,8 @@ void SelectionDAGBuilder::visitVPCmp(const VPCmpIntrinsic &VPIntrin) {
 
   if (VPIntrin.getOperand(0)->getType()->isFPOrFPVectorTy()) {
     Condition = getFCmpCondCode(CondCode);
-    if (DAG.isKnownNeverNaN(Op1) && DAG.isKnownNeverNaN(Op2))
+    SimplifyQuery SQ(DAG.getDataLayout(), &VPIntrin);
+    if (isKnownNeverNaN(Op1, SQ) && isKnownNeverNaN(Op2, SQ))
       Condition = getFCmpCodeWithoutNaN(Condition);
   } else {
     Condition = getICmpCondCode(CondCode);
@@ -8880,8 +8881,8 @@ void SelectionDAGBuilder::visitVPCmp(const VPCmpIntrinsic &VPIntrin) {
 
   EVT DestVT = DAG.getTargetLoweringInfo().getValueType(DAG.getDataLayout(),
                                                         VPIntrin.getType());
-  setValue(&VPIntrin,
-           DAG.getSetCCVP(DL, DestVT, Op1, Op2, Condition, MaskOp, EVL));
+  setValue(&VPIntrin, DAG.getSetCCVP(DL, DestVT, getValue(Op1), getValue(Op2),
+                                     Condition, MaskOp, EVL));
 }
 
 void SelectionDAGBuilder::visitVectorPredicationIntrinsic(