Revert r147945 which disabled an addressing mode transformation. I had

hoped this would revive one of the llvm-gcc selfhost build bots, but it
didn't so it doesn't appear that my transform is the culprit.

If anyone else is seeing failures, please let me know!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147957 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/X86/X86ISelDAGToDAG.cpp

@@ -847,10 +847,6 @@ static bool FoldMaskAndShiftToScale(SelectionDAG &DAG, SDValue N,
                                     uint64_t Mask,
                                     SDValue Shift, SDValue X,
                                     X86ISelAddressMode &AM) {
-  // FIXME!! Hack to disable this and see if it is responsible for a miscompile
-  // on llvm-gcc's selfhost.
-  return true;
-
   if (Shift.getOpcode() != ISD::SRL || !Shift.hasOneUse() ||
       !isa<ConstantSDNode>(Shift.getOperand(1)))
     return true;