-Revert parts of 84326 and 84411. Distinquishing between fixed and non-fixed
stack slots and giving them different PseudoSourceValue's did not fix the
problem of post-alloc scheduling miscompiling llvm itself.
- Apply Dan's conservative workaround by assuming any non fixed stack slots can
alias other memory locations. This means a load from spill slot #1 cannot 
move above a store of spill slot #2. 
- Enable post-alloc scheduling for x86 at optimization leverl Default and above.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84424 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/TargetInstrInfoImpl.cpp b/lib/CodeGen/TargetInstrInfoImpl.cpp
index 0a925f1..c646869 100644
--- a/lib/CodeGen/TargetInstrInfoImpl.cpp
+++ b/lib/CodeGen/TargetInstrInfoImpl.cpp
@@ -186,11 +186,8 @@
          "Folded a use to a non-load!");
   const MachineFrameInfo &MFI = *MF.getFrameInfo();
   assert(MFI.getObjectOffset(FrameIndex) != -1);
-  const Value *SV = MFI.isFixedObjectIndex(FrameIndex)
-    ? PseudoSourceValue::getFixedStack(FrameIndex)
-    : PseudoSourceValue::getStack();
   MachineMemOperand *MMO =
-    MF.getMachineMemOperand(SV,
+    MF.getMachineMemOperand(PseudoSourceValue::getFixedStack(FrameIndex),
                             Flags, /*Offset=*/0,
                             MFI.getObjectSize(FrameIndex),
                             MFI.getObjectAlignment(FrameIndex));