[PowerPC] Don't mark the return-address slot as immutable
It is tempting to mark the fixed stack slot used to store the return address as
immutable when lowering @llvm.returnaddress(i32 0). Unfortunately, within the
function, it is not completely immutable: it is written during the function
prologue. When using post-RA instruction scheduling, the prologue instructions
are available for scheduling, and we're not free to interchange the order of a
particular store in the prologue with loads from that stack location.
Fixes PR21976.
llvm-svn: 224761
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 1838462..06cf9af 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -5164,7 +5164,7 @@
// Find out what the fix offset of the frame pointer save area.
int LROffset = PPCFrameLowering::getReturnSaveOffset(isPPC64, isDarwinABI);
// Allocate the frame index for frame pointer save area.
- RASI = MF.getFrameInfo()->CreateFixedObject(isPPC64? 8 : 4, LROffset, true);
+ RASI = MF.getFrameInfo()->CreateFixedObject(isPPC64? 8 : 4, LROffset, false);
// Save the result.
FI->setReturnAddrSaveIndex(RASI);
}