[llvm] r278572 - X86: Stop dereferencing end() in X86FrameLowering::emitEpilogue
Duncan P. N. Exon Smith via llvm-commits
llvm-commits at lists.llvm.org
Fri Aug 12 15:43:33 PDT 2016
Author: dexonsmith
Date: Fri Aug 12 17:43:33 2016
New Revision: 278572
URL: http://llvm.org/viewvc/llvm-project?rev=278572&view=rev
Log:
X86: Stop dereferencing end() in X86FrameLowering::emitEpilogue
On a Windows build of Chromium, r278532 (up to r278539)
X86FrameLowering::emitEpilogue because it wasn't wary enough of the
return of MachineBasicBlock::getFirstTerminator. Guard all the uses
here.
Note that r278532 *looks* like an NFC commit (just an API change), but
it removes a couple of layers of abstraction and is probably causing
optimization differences in MSVC.
Modified:
llvm/trunk/lib/Target/X86/X86FrameLowering.cpp
Modified: llvm/trunk/lib/Target/X86/X86FrameLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86FrameLowering.cpp?rev=278572&r1=278571&r2=278572&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86FrameLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86FrameLowering.cpp Fri Aug 12 17:43:33 2016
@@ -1480,7 +1480,9 @@ void X86FrameLowering::emitEpilogue(Mach
const MachineFrameInfo &MFI = MF.getFrameInfo();
X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
MachineBasicBlock::iterator MBBI = MBB.getFirstTerminator();
- unsigned RetOpcode = MBBI->getOpcode();
+ Optional<unsigned> RetOpcode;
+ if (MBBI != MBB.end())
+ RetOpcode = MBBI->getOpcode();
DebugLoc DL;
if (MBBI != MBB.end())
DL = MBBI->getDebugLoc();
@@ -1493,7 +1495,7 @@ void X86FrameLowering::emitEpilogue(Mach
bool IsWin64Prologue = MF.getTarget().getMCAsmInfo()->usesWindowsCFI();
bool NeedsWinCFI =
IsWin64Prologue && MF.getFunction()->needsUnwindTableEntry();
- bool IsFunclet = isFuncletReturnInstr(*MBBI);
+ bool IsFunclet = MBBI == MBB.end() ? false : isFuncletReturnInstr(*MBBI);
MachineBasicBlock *TargetMBB = nullptr;
// Get the number of bytes to allocate from the FrameInfo.
@@ -1502,7 +1504,7 @@ void X86FrameLowering::emitEpilogue(Mach
unsigned CSSize = X86FI->getCalleeSavedFrameSize();
uint64_t NumBytes = 0;
- if (MBBI->getOpcode() == X86::CATCHRET) {
+ if (RetOpcode && *RetOpcode == X86::CATCHRET) {
// SEH shouldn't use catchret.
assert(!isAsynchronousEHPersonality(
classifyEHPersonality(MF.getFunction()->getPersonalityFn())) &&
@@ -1516,7 +1518,7 @@ void X86FrameLowering::emitEpilogue(Mach
BuildMI(MBB, MBBI, DL, TII.get(Is64Bit ? X86::POP64r : X86::POP32r),
MachineFramePtr)
.setMIFlag(MachineInstr::FrameDestroy);
- } else if (MBBI->getOpcode() == X86::CLEANUPRET) {
+ } else if (RetOpcode && *RetOpcode == X86::CLEANUPRET) {
NumBytes = getWinEHFuncletFrameSize(MF);
assert(hasFP(MF) && "EH funclets without FP not yet implemented");
BuildMI(MBB, MBBI, DL, TII.get(Is64Bit ? X86::POP64r : X86::POP32r),
@@ -1629,7 +1631,7 @@ void X86FrameLowering::emitEpilogue(Mach
if (NeedsWinCFI)
BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_Epilogue));
- if (!isTailCallOpcode(RetOpcode)) {
+ if (!RetOpcode || !isTailCallOpcode(*RetOpcode)) {
// Add the return addr area delta back since we are not tail calling.
int Offset = -1 * X86FI->getTCReturnAddrDelta();
assert(Offset >= 0 && "TCDelta should never be positive");
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