[llvm] [DAGCombiner] Remove `NoSignedZerosFPMath` uses in `visitFADD` (PR #160635)

[via llvm-commits]

https://github.com/paperchalice created https://github.com/llvm/llvm-project/pull/160635

Remove these global flags and use node level flags instead.

>From 8f07ef06973fe5722af7482e49fff2c5112758f1 Mon Sep 17 00:00:00 2001
From: PaperChalice <liujunchang97 at outlook.com>
Date: Thu, 25 Sep 2025 11:32:01 +0800
Subject: [PATCH] [DAGCombiner] Remove `NoSignedZerosFPMath` uses in
 `visitFADD`

---
 llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index a6ba6e518899f..c81568672de3c 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -17770,7 +17770,7 @@ SDValue DAGCombiner::visitFADD(SDNode *N) {
   // N0 + -0.0 --> N0 (also allowed with +0.0 and fast-math)
   ConstantFPSDNode *N1C = isConstOrConstSplatFP(N1, true);
   if (N1C && N1C->isZero())
-    if (N1C->isNegative() || Options.NoSignedZerosFPMath || Flags.hasNoSignedZeros())
+    if (N1C->isNegative() || Flags.hasNoSignedZeros())
       return N0;
 
   if (SDValue NewSel = foldBinOpIntoSelect(N))
@@ -17823,11 +17823,10 @@ SDValue DAGCombiner::visitFADD(SDNode *N) {
       return DAG.getConstantFP(0.0, DL, VT);
   }
 
-  // If 'unsafe math' or reassoc and nsz, fold lots of things.
+  // If reassoc and nsz, fold lots of things.
   // TODO: break out portions of the transformations below for which Unsafe is
   //       considered and which do not require both nsz and reassoc
-  if ((Options.NoSignedZerosFPMath ||
-       (Flags.hasAllowReassociation() && Flags.hasNoSignedZeros())) &&
+  if (Flags.hasAllowReassociation() && Flags.hasNoSignedZeros() &&
       AllowNewConst) {
     // fadd (fadd x, c1), c2 -> fadd x, c1 + c2
     if (N1CFP && N0.getOpcode() == ISD::FADD &&
@@ -17911,10 +17910,9 @@ SDValue DAGCombiner::visitFADD(SDNode *N) {
                            DAG.getConstantFP(4.0, DL, VT));
       }
     }
-  } // enable-unsafe-fp-math && AllowNewConst
+  } // reassoc && nsz && AllowNewConst
 
-  if ((Options.NoSignedZerosFPMath ||
-       (Flags.hasAllowReassociation() && Flags.hasNoSignedZeros()))) {
+  if (Flags.hasAllowReassociation() && Flags.hasNoSignedZeros()) {
     // Fold fadd(vecreduce(x), vecreduce(y)) -> vecreduce(fadd(x, y))
     if (SDValue SD = reassociateReduction(ISD::VECREDUCE_FADD, ISD::FADD, DL,
                                           VT, N0, N1, Flags))