-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.

llvm-svn: 84424

1 files changed, 2 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp
index 9c22202eb97..adcc5322721 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp
@@ -4196,11 +4196,9 @@ SelectionDAGLowering::visitIntrinsicCall(CallInst &I, unsigned Intrinsic) {
     SDValue FIN = DAG.getFrameIndex(FI, PtrTy);
 
     // Store the stack protector onto the stack.
-    const Value *SV = MFI->isFixedObjectIndex(FI)
-      ? PseudoSourceValue::getFixedStack(FI)
-      : PseudoSourceValue::getStack();
     SDValue Result = DAG.getStore(getRoot(), getCurDebugLoc(), Src, FIN,
-                                  SV, 0, true);
+                                  PseudoSourceValue::getFixedStack(FI),
+                                  0, true);
     setValue(&I, Result);
     DAG.setRoot(Result);
     return 0;