[X86] Swap NewX and NewY for ordered elements for minimumnum/maximumnum

It is incorrect to just check for NewX and return its ordered elements.

Author: phoebewang

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -29502,16 +29502,23 @@ static SDValue LowerFMINIMUM_FMAXIMUM(SDValue Op, const X86Subtarget &Subtarget,
       DAG.isKnownNeverNaN(IsNum ? NewX : NewY))
     std::swap(NewX, NewY);
 
+  if (!IgnoreNaN && IsNum && !DAG.isKnownNeverNaN(NewY)) {
+    SDValue IsOrdered = DAG.getSetCC(DL, SetCCType, NewX, NewX, ISD::SETO);
+    SDValue X = DAG.getSelect(DL, VT, IsOrdered, NewY, NewX);
+    SDValue Y = DAG.getSelect(DL, VT, IsOrdered, NewX, NewY);
+    NewX = X;
+    NewY = Y;
+  }
+
   SDValue MinMax = DAG.getNode(MinMaxOp, DL, VT, NewX, NewY, Op->getFlags());
 
-  if (IgnoreNaN || DAG.isKnownNeverNaN(IsNum ? NewY : NewX))
+  if (IgnoreNaN || IsNum || DAG.isKnownNeverNaN(NewX))
     return MinMax;
 
   if (DAG.isKnownNeverNaN(NewX))
     NewX = NewY;
 
-  SDValue IsNaN =
-      DAG.getSetCC(DL, SetCCType, NewX, NewX, IsNum ? ISD::SETO : ISD::SETUO);
+  SDValue IsNaN = DAG.getSetCC(DL, SetCCType, NewX, NewX, ISD::SETUO);
 
   return DAG.getSelect(DL, VT, IsNaN, NewX, MinMax);
 }