expandFMINIMUM_FMAXIMUM: FMAXNUM/FMINNUM treat +0>-0

ISD::FMAXNUM and ISD::FMINNUM treat +0.0>-0.0 now,
so let's set MinMaxMustRespectOrderedZero for it.

Author: wzssyqa

llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp

@@ -8573,15 +8573,14 @@ SDValue TargetLowering::expandFMINIMUM_FMAXIMUM(SDNode *N,
   unsigned CompOpcIeee = IsMax ? ISD::FMAXNUM_IEEE : ISD::FMINNUM_IEEE;
   unsigned CompOpc = IsMax ? ISD::FMAXNUM : ISD::FMINNUM;
 
-  // FIXME: We should probably define fminnum/fmaxnum variants with correct
-  // signed zero behavior.
   bool MinMaxMustRespectOrderedZero = false;
 
   if (isOperationLegalOrCustom(CompOpcIeee, VT)) {
     MinMax = DAG.getNode(CompOpcIeee, DL, VT, LHS, RHS, Flags);
     MinMaxMustRespectOrderedZero = true;
   } else if (isOperationLegalOrCustom(CompOpc, VT)) {
     MinMax = DAG.getNode(CompOpc, DL, VT, LHS, RHS, Flags);
+    MinMaxMustRespectOrderedZero = true;
   } else {
     if (VT.isVector() && !isOperationLegalOrCustom(ISD::VSELECT, VT))
       return DAG.UnrollVectorOp(N);