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Simplify the alignment handling in FDE emission.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@252271 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Rafael Espindola 2015-11-06 03:02:51 +00:00
parent 63ab0b3c13
commit bf27814484
1 changed files with 15 additions and 16 deletions
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31
lib/MC/MCDwarf.cpp
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@ -1015,7 +1015,8 @@ public:
unsigned personalityEncoding, const MCSymbol *lsda,
bool IsSignalFrame, unsigned lsdaEncoding,
bool IsSimple);
MCSymbol *EmitFDE(const MCSymbol &cieStart, const MCDwarfFrameInfo &frame);
void EmitFDE(const MCSymbol &cieStart, const MCDwarfFrameInfo &frame,
bool LastInSection);
void EmitCFIInstructions(ArrayRef<MCCFIInstruction> Instrs,
MCSymbol *BaseLabel);
void EmitCFIInstruction(const MCCFIInstruction &Instr);
@ -1368,8 +1369,9 @@ const MCSymbol &FrameEmitterImpl::EmitCIE(const MCSymbol *personality,
return *sectionStart;
}
MCSymbol *FrameEmitterImpl::EmitFDE(const MCSymbol &cieStart,
const MCDwarfFrameInfo &frame) {
void FrameEmitterImpl::EmitFDE(const MCSymbol &cieStart,
const MCDwarfFrameInfo &frame,
bool LastInSection) {
MCContext &context = Streamer.getContext();
MCSymbol *fdeStart = context.createTempSymbol();
MCSymbol *fdeEnd = context.createTempSymbol();
@ -1426,9 +1428,13 @@ MCSymbol *FrameEmitterImpl::EmitFDE(const MCSymbol &cieStart,
EmitCFIInstructions(frame.Instructions, frame.Begin);
// Padding
Streamer.EmitValueToAlignment(PCSize);
// The size of a .eh_frame section has to be a multiple of the alignment
// since a null CIE is interpreted as the end. Old systems overaligned
// .eh_frame, so we do too and account for it in the last FDE.
unsigned Align = LastInSection ? asmInfo->getPointerSize() : PCSize;
Streamer.EmitValueToAlignment(Align);
return fdeEnd;
Streamer.EmitLabel(fdeEnd);
}
namespace {
@ -1519,22 +1525,19 @@ void MCDwarfFrameEmitter::Emit(MCObjectStreamer &Streamer, MCAsmBackend *MAB,
Streamer.EmitLabel(SectionStart);
Emitter.setSectionStart(SectionStart);
MCSymbol *FDEEnd = nullptr;
DenseMap<CIEKey, const MCSymbol *> CIEStarts;
const MCSymbol *DummyDebugKey = nullptr;
bool CanOmitDwarf = MOFI->getOmitDwarfIfHaveCompactUnwind();
for (const MCDwarfFrameInfo &Frame : FrameArray) {
for (auto I = FrameArray.begin(), E = FrameArray.end(); I != E;) {
const MCDwarfFrameInfo &Frame = *I;
++I;
if (CanOmitDwarf && Frame.CompactUnwindEncoding !=
MOFI->getCompactUnwindDwarfEHFrameOnly())
// Don't generate an EH frame if we don't need one. I.e., it's taken care
// of by the compact unwind encoding.
continue;
// Close the previous FDE.
if (FDEEnd)
Streamer.EmitLabel(FDEEnd);
CIEKey Key(Frame.Personality, Frame.PersonalityEncoding,
Frame.LsdaEncoding, Frame.IsSignalFrame, Frame.IsSimple);
const MCSymbol *&CIEStart = IsEH ? CIEStarts[Key] : DummyDebugKey;
@ -1543,12 +1546,8 @@ void MCDwarfFrameEmitter::Emit(MCObjectStreamer &Streamer, MCAsmBackend *MAB,
Frame.Lsda, Frame.IsSignalFrame,
Frame.LsdaEncoding, Frame.IsSimple);
FDEEnd = Emitter.EmitFDE(*CIEStart, Frame);
Emitter.EmitFDE(*CIEStart, Frame, I == E);
}
Streamer.EmitValueToAlignment(Context.getAsmInfo()->getPointerSize());
if (FDEEnd)
Streamer.EmitLabel(FDEEnd);
}
void MCDwarfFrameEmitter::EmitAdvanceLoc(MCObjectStreamer &Streamer,