[llvm] [DAGCombiner] Remove NoSignedZerosFPMath uses in visitFSUB (PR #160974)

[via llvm-commits]

https://github.com/paperchalice created https://github.com/llvm/llvm-project/pull/160974

None

>From 56a6e8410592c394213e6f80938cc11980591753 Mon Sep 17 00:00:00 2001
From: PaperChalice <liujunchang97 at outlook.com>
Date: Sat, 27 Sep 2025 11:11:29 +0800
Subject: [PATCH] [DAGCombiner] Remove NoSignedZerosFPMath uses in visitFSUB

---
 llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index c81568672de3c..77df4b4598c48 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -17983,8 +17983,7 @@ SDValue DAGCombiner::visitFSUB(SDNode *N) {
 
   // (fsub A, 0) -> A
   if (N1CFP && N1CFP->isZero()) {
-    if (!N1CFP->isNegative() || Options.NoSignedZerosFPMath ||
-        Flags.hasNoSignedZeros()) {
+    if (!N1CFP->isNegative() || Flags.hasNoSignedZeros()) {
       return N0;
     }
   }
@@ -17997,8 +17996,7 @@ SDValue DAGCombiner::visitFSUB(SDNode *N) {
 
   // (fsub -0.0, N1) -> -N1
   if (N0CFP && N0CFP->isZero()) {
-    if (N0CFP->isNegative() ||
-        (Options.NoSignedZerosFPMath || Flags.hasNoSignedZeros())) {
+    if (N0CFP->isNegative() || Flags.hasNoSignedZeros()) {
       // We cannot replace an FSUB(+-0.0,X) with FNEG(X) when denormals are
       // flushed to zero, unless all users treat denorms as zero (DAZ).
       // FIXME: This transform will change the sign of a NaN and the behavior
@@ -18014,8 +18012,7 @@ SDValue DAGCombiner::visitFSUB(SDNode *N) {
     }
   }
 
-  if ((Options.NoSignedZerosFPMath ||
-       (Flags.hasAllowReassociation() && Flags.hasNoSignedZeros())) &&
+  if (Flags.hasAllowReassociation() && Flags.hasNoSignedZeros() &&
       N1.getOpcode() == ISD::FADD) {
     // X - (X + Y) -> -Y
     if (N0 == N1->getOperand(0))