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[PowerPC] Fix unwind info with dynamic stack realignment

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Summary:
PowerPC DWARF unwind info defined CFA as SP + offset even in a function
where the stack had been dynamically realigned. This clearly doesn't
work because the offset from SP to CFA is not a constant. Fix it by
defining CFA as BP instead.

This was causing the AddressSanitizer null_deref test to fail 50% of
the time, depending on whether SP happened to be 32-byte aligned on
entry to a particular function or not.

Reviewers: willschm, uweigand, hfinkel

Reviewed By: hfinkel

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D6410

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222996 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jay Foad
2014-12-01 09:42:32 +00:00
parent 5e6e75a48e
commit 8b9cea42db
2 changed files with 35 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files

39
lib/Target/PowerPC/PPCFrameLowering.cpp
View File

@@ -505,7 +505,7 @@ void PPCFrameLowering::emitPrologue(MachineFunction &MF) const {
MachineModuleInfo &MMI = MF.getMMI();
const MCRegisterInfo *MRI = MMI.getContext().getRegisterInfo();
DebugLoc dl;
bool needsFrameMoves = MMI.hasDebugInfo() ||
bool needsCFI = MMI.hasDebugInfo() ||
MF.getFunction()->needsUnwindTableEntry();
bool isPIC = MF.getTarget().getRelocationModel() == Reloc::PIC_;
@@ -726,17 +726,28 @@ void PPCFrameLowering::emitPrologue(MachineFunction &MF) const {
.addReg(ScratchReg);
}
// Add the "machine moves" for the instructions we generated above, but in
// reverse order.
if (needsFrameMoves) {
// Show update of SP.
assert(NegFrameSize);
unsigned CFIIndex = MMI.addFrameInst(
MCCFIInstruction::createDefCfaOffset(nullptr, NegFrameSize));
// Add Call Frame Information for the instructions we generated above.
if (needsCFI) {
unsigned CFIIndex;
if (HasBP) {
// Define CFA in terms of BP. Do this in preference to using FP/SP,
// because if the stack needed aligning then CFA won't be at a fixed
// offset from FP/SP.
unsigned Reg = MRI->getDwarfRegNum(BPReg, true);
CFIIndex = MMI.addFrameInst(
MCCFIInstruction::createDefCfaRegister(nullptr, Reg));
} else {
// Adjust the definition of CFA to account for the change in SP.
assert(NegFrameSize);
CFIIndex = MMI.addFrameInst(
MCCFIInstruction::createDefCfaOffset(nullptr, NegFrameSize));
}
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
if (HasFP) {
// Describe where FP was saved, at a fixed offset from CFA.
unsigned Reg = MRI->getDwarfRegNum(FPReg, true);
CFIIndex = MMI.addFrameInst(
MCCFIInstruction::createOffset(nullptr, Reg, FPOffset));
@@ -745,6 +756,7 @@ void PPCFrameLowering::emitPrologue(MachineFunction &MF) const {
}
if (HasBP) {
// Describe where BP was saved, at a fixed offset from CFA.
unsigned Reg = MRI->getDwarfRegNum(BPReg, true);
CFIIndex = MMI.addFrameInst(
MCCFIInstruction::createOffset(nullptr, Reg, BPOffset));
@@ -753,6 +765,7 @@ void PPCFrameLowering::emitPrologue(MachineFunction &MF) const {
}
if (MustSaveLR) {
// Describe where LR was saved, at a fixed offset from CFA.
unsigned Reg = MRI->getDwarfRegNum(LRReg, true);
CFIIndex = MMI.addFrameInst(
MCCFIInstruction::createOffset(nullptr, Reg, LROffset));
@@ -767,8 +780,9 @@ void PPCFrameLowering::emitPrologue(MachineFunction &MF) const {
.addReg(SPReg)
.addReg(SPReg);
if (needsFrameMoves) {
// Mark effective beginning of when frame pointer is ready.
if (!HasBP && needsCFI) {
// Change the definition of CFA from SP+offset to FP+offset, because SP
// will change at every alloca.
unsigned Reg = MRI->getDwarfRegNum(FPReg, true);
unsigned CFIIndex = MMI.addFrameInst(
MCCFIInstruction::createDefCfaRegister(nullptr, Reg));
@@ -778,8 +792,9 @@ void PPCFrameLowering::emitPrologue(MachineFunction &MF) const {
}
}
if (needsFrameMoves) {
// Add callee saved registers to move list.
if (needsCFI) {
// Describe where callee saved registers were saved, at fixed offsets from
// CFA.
const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
for (unsigned I = 0, E = CSI.size(); I != E; ++I) {
unsigned Reg = CSI[I].getReg();