ARM: Avoid dereferencing end() in ARMFrameLowering::emitPrologue
llvm::tryFoldSPUpdateIntoPushPop assumes its arguments are valid
MachineInstrs. Update ARMFrameLowering::emitPrologue to respect that;
when LastPush==end(), it can't possibly be a push instruction anyway.
llvm-svn: 278880
diff --git a/llvm/lib/Target/ARM/ARMFrameLowering.cpp b/llvm/lib/Target/ARM/ARMFrameLowering.cpp
index 8535075..0540745 100644
--- a/llvm/lib/Target/ARM/ARMFrameLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMFrameLowering.cpp
@@ -413,7 +413,8 @@
// .cfi_offset operations will reflect that.
if (DPRGapSize) {
assert(DPRGapSize == 4 && "unexpected alignment requirements for DPRs");
- if (tryFoldSPUpdateIntoPushPop(STI, MF, &*LastPush, DPRGapSize))
+ if (LastPush != MBB.end() &&
+ tryFoldSPUpdateIntoPushPop(STI, MF, &*LastPush, DPRGapSize))
DefCFAOffsetCandidates.addExtraBytes(LastPush, DPRGapSize);
else {
emitSPUpdate(isARM, MBB, MBBI, dl, TII, -DPRGapSize,