[llvm] [DAGCombiner] Remove most `NoSignedZerosFPMath` uses (PR #161180)

[via llvm-commits]

https://github.com/paperchalice updated https://github.com/llvm/llvm-project/pull/161180

>From 0891cc1fbbf9988b94a2b1e86fbf75db8b81ee3c Mon Sep 17 00:00:00 2001
From: PaperChalice <liujunchang97 at outlook.com>
Date: Mon, 29 Sep 2025 19:22:45 +0800
Subject: [PATCH] [DAGCombiner] Remove most `NoSignedZerosFPMath` uses Remained
 two uses are related to fneg and foldFPToIntToFP

---
 llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 77df4b4598c48..204e1f0c75e00 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -11849,9 +11849,7 @@ static bool isLegalToCombineMinNumMaxNum(SelectionDAG &DAG, SDValue LHS,
   if (!VT.isFloatingPoint())
     return false;
 
-  const TargetOptions &Options = DAG.getTarget().Options;
-
-  return (Flags.hasNoSignedZeros() || Options.NoSignedZerosFPMath) &&
+  return Flags.hasNoSignedZeros() &&
          TLI.isProfitableToCombineMinNumMaxNum(VT) &&
          (Flags.hasNoNaNs() ||
           (DAG.isKnownNeverNaN(RHS) && DAG.isKnownNeverNaN(LHS)));
@@ -17351,7 +17349,7 @@ SDValue DAGCombiner::visitFSUBForFMACombine(SDNode *N) {
   // Always prefer FMAD to FMA for precision.
   unsigned PreferredFusedOpcode = HasFMAD ? ISD::FMAD : ISD::FMA;
   bool Aggressive = TLI.enableAggressiveFMAFusion(VT);
-  bool NoSignedZero = Options.NoSignedZerosFPMath || Flags.hasNoSignedZeros();
+  bool NoSignedZero = Flags.hasNoSignedZeros();
 
   // Is the node an FMUL and contractable either due to global flags or
   // SDNodeFlags.
@@ -18327,11 +18325,9 @@ template <class MatchContextClass> SDValue DAGCombiner::visitFMA(SDNode *N) {
       return matcher.getNode(ISD::FMA, DL, VT, NegN0, NegN1, N2);
   }
 
-  // FIXME: use fast math flags instead of Options.UnsafeFPMath
-  // TODO: Finally migrate away from global TargetOptions.
   if ((Options.NoNaNsFPMath && Options.NoInfsFPMath) ||
       (N->getFlags().hasNoNaNs() && N->getFlags().hasNoInfs())) {
-    if (Options.NoSignedZerosFPMath || N->getFlags().hasNoSignedZeros() ||
+    if (N->getFlags().hasNoSignedZeros() ||
         (N2CFP && !N2CFP->isExactlyValue(-0.0))) {
       if (N0CFP && N0CFP->isZero())
         return N2;
@@ -18636,8 +18632,7 @@ SDValue DAGCombiner::visitFDIV(SDNode *N) {
   }
 
   // Fold X/Sqrt(X) -> Sqrt(X)
-  if ((Options.NoSignedZerosFPMath || Flags.hasNoSignedZeros()) &&
-      Flags.hasAllowReassociation())
+  if (Flags.hasNoSignedZeros() && Flags.hasAllowReassociation())
     if (N1.getOpcode() == ISD::FSQRT && N0 == N1.getOperand(0))
       return N1;