[llvm] [X86] Remove `UnsafeFPMath` uses (PR #151667)

[via llvm-commits]

https://github.com/paperchalice created https://github.com/llvm/llvm-project/pull/151667

Remove `UnsafeFPMath` in X86 part, it blocks some bugfixes related to clang and the ultimate goal is to remove `resetTargetOptions` method in `TargetMachine`, see FIXME in `resetTargetOptions`.
See also https://discourse.llvm.org/t/rfc-honor-pragmas-with-ffp-contract-fast
https://discourse.llvm.org/t/allowfpopfusion-vs-sdnodeflags-hasallowcontract 

>From 92be5e863aa600ca302e29c9d3af5f57e95a8827 Mon Sep 17 00:00:00 2001
From: PaperChalice <liujunchang97 at outlook.com>
Date: Fri, 1 Aug 2025 16:06:47 +0800
Subject: [PATCH] [X86] Remove `UnsafeFPMath` uses

---
 llvm/lib/Target/X86/X86ISelLowering.cpp | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index bbbb1d9057a72..bf7ac9d831caa 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -8393,9 +8393,9 @@ static bool isAddSubOrSubAdd(const BuildVectorSDNode *BV,
 /// is illegal sometimes. E.g. 512-bit ADDSUB is not available, while 512-bit
 /// FMADDSUB is.
 static bool isFMAddSubOrFMSubAdd(const X86Subtarget &Subtarget,
-                                 SelectionDAG &DAG,
-                                 SDValue &Opnd0, SDValue &Opnd1, SDValue &Opnd2,
-                                 unsigned ExpectedUses) {
+                                 SelectionDAG &DAG, SDValue &Opnd0,
+                                 SDValue &Opnd1, SDValue &Opnd2,
+                                 SDNodeFlags Flags, unsigned ExpectedUses) {
   if (Opnd0.getOpcode() != ISD::FMUL ||
       !Opnd0->hasNUsesOfValue(ExpectedUses, 0) || !Subtarget.hasAnyFMA())
     return false;
@@ -8406,7 +8406,7 @@ static bool isFMAddSubOrFMSubAdd(const X86Subtarget &Subtarget,
   // or MUL + ADDSUB to FMADDSUB.
   const TargetOptions &Options = DAG.getTarget().Options;
   bool AllowFusion =
-      (Options.AllowFPOpFusion == FPOpFusion::Fast || Options.UnsafeFPMath);
+      (Options.AllowFPOpFusion == FPOpFusion::Fast || Flags.hasAllowContract());
   if (!AllowFusion)
     return false;
 
@@ -8435,7 +8435,8 @@ static SDValue lowerToAddSubOrFMAddSub(const BuildVectorSDNode *BV,
 
   // Try to generate X86ISD::FMADDSUB node here.
   SDValue Opnd2;
-  if (isFMAddSubOrFMSubAdd(Subtarget, DAG, Opnd0, Opnd1, Opnd2, NumExtracts)) {
+  if (isFMAddSubOrFMSubAdd(Subtarget, DAG, Opnd0, Opnd1, Opnd2, BV->getFlags(),
+                           NumExtracts)) {
     unsigned Opc = IsSubAdd ? X86ISD::FMSUBADD : X86ISD::FMADDSUB;
     return DAG.getNode(Opc, DL, VT, Opnd0, Opnd1, Opnd2);
   }