[llvm] [CodeGen] Remove most NoNaNsFPMath uses (PR #163484)

[via llvm-commits]

https://github.com/paperchalice created https://github.com/llvm/llvm-project/pull/163484

None

>From 29a672d666d96de3131433a24a5804e8b13602c5 Mon Sep 17 00:00:00 2001
From: PaperChalice <liujunchang97 at outlook.com>
Date: Wed, 15 Oct 2025 09:29:21 +0800
Subject: [PATCH] [CodeGen] Remove most NoNaNsFPMath uses

---
 llvm/lib/CodeGen/GlobalISel/Utils.cpp                 | 3 +--
 llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp         | 9 +++------
 llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp        | 2 +-
 llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp | 4 ++--
 4 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/llvm/lib/CodeGen/GlobalISel/Utils.cpp b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
index 055fdc6ad7213..ca82857319abc 100644
--- a/llvm/lib/CodeGen/GlobalISel/Utils.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
@@ -818,8 +818,7 @@ bool llvm::isKnownNeverNaN(Register Val, const MachineRegisterInfo &MRI,
   if (!DefMI)
     return false;
 
-  const TargetMachine& TM = DefMI->getMF()->getTarget();
-  if (DefMI->getFlag(MachineInstr::FmNoNans) || TM.Options.NoNaNsFPMath)
+  if (DefMI->getFlag(MachineInstr::FmNoNans))
     return true;
 
   // If the value is a constant, we can obviously see if it is a NaN or not.
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 358e060d2c6d3..a1f319550cb15 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -17759,7 +17759,6 @@ SDValue DAGCombiner::visitFADD(SDNode *N) {
   bool N1CFP = DAG.isConstantFPBuildVectorOrConstantFP(N1);
   EVT VT = N->getValueType(0);
   SDLoc DL(N);
-  const TargetOptions &Options = DAG.getTarget().Options;
   SDNodeFlags Flags = N->getFlags();
   SelectionDAG::FlagInserter FlagsInserter(DAG, N);
 
@@ -17825,7 +17824,7 @@ SDValue DAGCombiner::visitFADD(SDNode *N) {
   bool AllowNewConst = (Level < AfterLegalizeDAG);
 
   // If nnan is enabled, fold lots of things.
-  if ((Options.NoNaNsFPMath || Flags.hasNoNaNs()) && AllowNewConst) {
+  if (Flags.hasNoNaNs() && AllowNewConst) {
     // If allowed, fold (fadd (fneg x), x) -> 0.0
     if (N0.getOpcode() == ISD::FNEG && N0.getOperand(0) == N1)
       return DAG.getConstantFP(0.0, DL, VT);
@@ -17974,7 +17973,6 @@ SDValue DAGCombiner::visitFSUB(SDNode *N) {
   ConstantFPSDNode *N1CFP = isConstOrConstSplatFP(N1, true);
   EVT VT = N->getValueType(0);
   SDLoc DL(N);
-  const TargetOptions &Options = DAG.getTarget().Options;
   const SDNodeFlags Flags = N->getFlags();
   SelectionDAG::FlagInserter FlagsInserter(DAG, N);
 
@@ -18002,7 +18000,7 @@ SDValue DAGCombiner::visitFSUB(SDNode *N) {
 
   if (N0 == N1) {
     // (fsub x, x) -> 0.0
-    if (Options.NoNaNsFPMath || Flags.hasNoNaNs())
+    if (Flags.hasNoNaNs())
       return DAG.getConstantFP(0.0f, DL, VT);
   }
 
@@ -18339,8 +18337,7 @@ template <class MatchContextClass> SDValue DAGCombiner::visitFMA(SDNode *N) {
       return matcher.getNode(ISD::FMA, DL, VT, NegN0, NegN1, N2);
   }
 
-  if ((Options.NoNaNsFPMath && N->getFlags().hasNoInfs()) ||
-      (N->getFlags().hasNoNaNs() && N->getFlags().hasNoInfs())) {
+  if (N->getFlags().hasNoNaNs() && N->getFlags().hasNoInfs()) {
     if (N->getFlags().hasNoSignedZeros() ||
         (N2CFP && !N2CFP->isExactlyValue(-0.0))) {
       if (N0CFP && N0CFP->isZero())
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 90edaf3ef5471..9b8582c809f66 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -5877,7 +5877,7 @@ bool SelectionDAG::isKnownNeverNaN(SDValue Op, const APInt &DemandedElts,
   assert(!DemandedElts.isZero() && "No demanded elements");
 
   // If we're told that NaNs won't happen, assume they won't.
-  if (getTarget().Options.NoNaNsFPMath || Op->getFlags().hasNoNaNs())
+  if (Op->getFlags().hasNoNaNs())
     return true;
 
   if (Depth >= MaxRecursionDepth)
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 0f2b5188fc10a..1fd549248dabc 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -2435,7 +2435,7 @@ SelectionDAGBuilder::EmitBranchForMergedCondition(const Value *Cond,
         FCmpInst::Predicate Pred =
             InvertCond ? FC->getInversePredicate() : FC->getPredicate();
         Condition = getFCmpCondCode(Pred);
-        if (TM.Options.NoNaNsFPMath)
+        if (dyn_cast<FPMathOperator>(FC)->hasNoNaNs())
           Condition = getFCmpCodeWithoutNaN(Condition);
       }
 
@@ -3711,7 +3711,7 @@ void SelectionDAGBuilder::visitFCmp(const FCmpInst &I) {
 
   ISD::CondCode Condition = getFCmpCondCode(predicate);
   auto *FPMO = cast<FPMathOperator>(&I);
-  if (FPMO->hasNoNaNs() || TM.Options.NoNaNsFPMath)
+  if (FPMO->hasNoNaNs())
     Condition = getFCmpCodeWithoutNaN(Condition);
 
   SDNodeFlags Flags;