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[AArch64] Fix the emission of WinCFI for pac-ret+leaf and SCS #147518

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Merged
atrosinenko merged 3 commits into from
Jul 12, 2025
Merged

[AArch64] Fix the emission of WinCFI for pac-ret+leaf and SCS #147518

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a36ad29
[AArch64] Fix the emission of WinCFI for pac-ret+leaf and SCS
atrosinenko Jul 8, 2025
8283078
Add CHECK lines for WinCFI assembly output
atrosinenko Jul 11, 2025
030554d
Add DWARFCFI- to COMPAT and V83A check lines
atrosinenko Jul 11, 2025
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32 changes: 23 additions & 9 deletions llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1746,7 +1746,7 @@ static void emitShadowCallStackEpilogue(const TargetInstrInfo &TII,
MachineFunction &MF,
MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI,
const DebugLoc &DL) {
const DebugLoc &DL, bool NeedsWinCFI) {
// Shadow call stack epilog: ldr x30, [x18, #-8]!
BuildMI(MBB, MBBI, DL, TII.get(AArch64::LDRXpre))
.addReg(AArch64::X18, RegState::Define)
Expand All @@ -1755,6 +1755,10 @@ static void emitShadowCallStackEpilogue(const TargetInstrInfo &TII,
.addImm(-8)
.setMIFlag(MachineInstr::FrameDestroy);

if (NeedsWinCFI)
BuildMI(MBB, MBBI, DL, TII.get(AArch64::SEH_Nop))
.setMIFlag(MachineInstr::FrameDestroy);

if (MF.getInfo<AArch64FunctionInfo>()->needsAsyncDwarfUnwindInfo(MF))
CFIInstBuilder(MBB, MBBI, MachineInstr::FrameDestroy)
.buildRestore(AArch64::X18);
Expand Down Expand Up @@ -1899,13 +1903,15 @@ void AArch64FrameLowering::emitPrologue(MachineFunction &MF,
BuildMI(MBB, MBBI, DL, TII->get(AArch64::PAUTH_PROLOGUE))
.setMIFlag(MachineInstr::FrameSetup);
}
if (NeedsWinCFI)
HasWinCFI = true; // AArch64PointerAuth pass will insert SEH_PACSignLR
// AArch64PointerAuth pass will insert SEH_PACSignLR
HasWinCFI |= NeedsWinCFI;
}

if (MFnI.needsShadowCallStackPrologueEpilogue(MF))
if (MFnI.needsShadowCallStackPrologueEpilogue(MF)) {
emitShadowCallStackPrologue(*TII, MF, MBB, MBBI, DL, NeedsWinCFI,
MFnI.needsDwarfUnwindInfo(MF));
HasWinCFI |= NeedsWinCFI;
}

if (EmitCFI && MFnI.isMTETagged()) {
BuildMI(MBB, MBBI, DL, TII->get(AArch64::EMITMTETAGGED))
Expand Down Expand Up @@ -1990,8 +1996,13 @@ void AArch64FrameLowering::emitPrologue(MachineFunction &MF,
"unexpected function without stack frame but with SVE objects");
// All of the stack allocation is for locals.
AFI->setLocalStackSize(NumBytes);
if (!NumBytes)
if (!NumBytes) {
if (NeedsWinCFI && HasWinCFI) {
BuildMI(MBB, MBBI, DL, TII->get(AArch64::SEH_PrologEnd))
.setMIFlag(MachineInstr::FrameSetup);
}
return;
}
// REDZONE: If the stack size is less than 128 bytes, we don't need
// to actually allocate.
if (canUseRedZone(MF)) {
Expand Down Expand Up @@ -2460,8 +2471,11 @@ void AArch64FrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock::iterator EpilogStartI = MBB.end();

auto FinishingTouches = make_scope_exit([&]() {
if (AFI->needsShadowCallStackPrologueEpilogue(MF))
emitShadowCallStackEpilogue(*TII, MF, MBB, MBB.getFirstTerminator(), DL);
if (AFI->needsShadowCallStackPrologueEpilogue(MF)) {
emitShadowCallStackEpilogue(*TII, MF, MBB, MBB.getFirstTerminator(), DL,
NeedsWinCFI);
HasWinCFI |= NeedsWinCFI;
}
if (EmitCFI)
emitCalleeSavedGPRRestores(MBB, MBB.getFirstTerminator());
if (AFI->shouldSignReturnAddress(MF)) {
Expand All @@ -2472,8 +2486,8 @@ void AArch64FrameLowering::emitEpilogue(MachineFunction &MF,
TII->get(AArch64::PAUTH_EPILOGUE))
.setMIFlag(MachineInstr::FrameDestroy);
}
if (NeedsWinCFI)
HasWinCFI = true; // AArch64PointerAuth pass will insert SEH_PACSignLR
// AArch64PointerAuth pass will insert SEH_PACSignLR
HasWinCFI |= NeedsWinCFI;
}
if (HasWinCFI) {
BuildMI(MBB, MBB.getFirstTerminator(), DL,
Expand Down
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