[X86] Remove isel patterns that include a vselect/X86selects and a strict FP node.

A vselect+strictfp node is not equivalent to a masked operation.
The exceptions of the strictfp node are not masked by a vselect
after it so we can't match it to a masked operation.

We already had a hack in IsLegalToFold to prevent these patterns from
matching. This patch removes that hack and removes the patterns.

Author: topperc

llvm/lib/Target/X86/X86ISelDAGToDAG.cpp

@@ -581,12 +581,6 @@ X86DAGToDAGISel::IsProfitableToFold(SDValue N, SDNode *U, SDNode *Root) const {
   if (!N.hasOneUse())
     return false;
 
-  // FIXME: Temporary hack to prevent strict floating point nodes from
-  // folding into masked operations illegally.
-  if (U == Root && Root->getOpcode() == ISD::VSELECT &&
-      N.getOpcode() != ISD::LOAD && N.getOpcode() != X86ISD::VBROADCAST_LOAD)
-    return false;
-
   if (N.getOpcode() != ISD::LOAD)
     return true;