Mark the return address stack slot as mutable when moving the return address

during a tail call. A parameter might overwrite this stack slot during the tail
call. 

The sequence during a tail call is:
1.) load return address to temp reg
2.) move parameters (might involve storing to return address stack slot)
3.) store return address to new location from temp reg

If the stack location is marked immutable CodeGen can colocate load (1) with the
store (3).

This fixes bug 6225.

llvm-svn: 96783

1 files changed, 2 insertions, 2 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 624d65bf1f7..7f9d0820b24 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -1744,7 +1744,7 @@ EmitTailCallStoreRetAddr(SelectionDAG & DAG, MachineFunction &MF,
   // Calculate the new stack slot for the return address.
   int SlotSize = Is64Bit ? 8 : 4;
   int NewReturnAddrFI =
-    MF.getFrameInfo()->CreateFixedObject(SlotSize, FPDiff-SlotSize, true,false);
+    MF.getFrameInfo()->CreateFixedObject(SlotSize, FPDiff-SlotSize, false, false);
   EVT VT = Is64Bit ? MVT::i64 : MVT::i32;
   SDValue NewRetAddrFrIdx = DAG.getFrameIndex(NewReturnAddrFI, VT);
   Chain = DAG.getStore(Chain, dl, RetAddrFrIdx, NewRetAddrFrIdx,
@@ -2377,7 +2377,7 @@ SDValue X86TargetLowering::getReturnAddressFrameIndex(SelectionDAG &DAG) {
     // Set up a frame object for the return address.
     uint64_t SlotSize = TD->getPointerSize();
     ReturnAddrIndex = MF.getFrameInfo()->CreateFixedObject(SlotSize, -SlotSize,
-                                                           true, false);
+                                                           false, false);
     FuncInfo->setRAIndex(ReturnAddrIndex);
   }