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| author | Iain Sandoe <iain@codesourcery.com> | 2014-01-08 10:22:54 +0000 |
|---|---|---|
| committer | Iain Sandoe <iain@codesourcery.com> | 2014-01-08 10:22:54 +0000 |
| commit | 618def651b59bd42c05bbd91d825af2fb2145683 (patch) | |
| tree | 36555c3765cf6201f06ca08bb7506eb29eb7d609 /llvm/lib/MC | |
| parent | 44946439e1d81f3e679a4fa60da6b44f00f4636e (diff) | |
| download | bcm5719-llvm-618def651b59bd42c05bbd91d825af2fb2145683.tar.gz bcm5719-llvm-618def651b59bd42c05bbd91d825af2fb2145683.zip | |
[patch] Adjust behavior of FDE cross-section relocs for targets that don't support abs-differences.
Modern versions of OSX/Darwin's ld (ld64 > 97.17) have an optimisation present that allows the back end to omit relocations (and replace them with an absolute difference) for FDE some text section refs.
This patch allows a backend to opt-in to this behaviour by setting "DwarfFDESymbolsUseAbsDiff". At present, this is only enabled for modern x86 OSX ports.
test changes by David Fang.
llvm-svn: 198744
Diffstat (limited to 'llvm/lib/MC')
| -rw-r--r-- | llvm/lib/MC/MCAsmInfo.cpp | 1 | ||||
| -rw-r--r-- | llvm/lib/MC/MCDwarf.cpp | 16 |
2 files changed, 11 insertions, 6 deletions
diff --git a/llvm/lib/MC/MCAsmInfo.cpp b/llvm/lib/MC/MCAsmInfo.cpp index 466a94d8e87..2c19e8511b3 100644 --- a/llvm/lib/MC/MCAsmInfo.cpp +++ b/llvm/lib/MC/MCAsmInfo.cpp @@ -84,6 +84,7 @@ MCAsmInfo::MCAsmInfo() { SupportsDebugInformation = false; ExceptionsType = ExceptionHandling::None; DwarfUsesRelocationsAcrossSections = true; + DwarfFDESymbolsUseAbsDiff = false; DwarfRegNumForCFI = false; NeedsDwarfSectionOffsetDirective = false; UseParensForSymbolVariant = false; diff --git a/llvm/lib/MC/MCDwarf.cpp b/llvm/lib/MC/MCDwarf.cpp index 479f4452d4a..12070f36ea6 100644 --- a/llvm/lib/MC/MCDwarf.cpp +++ b/llvm/lib/MC/MCDwarf.cpp @@ -839,8 +839,9 @@ static unsigned getSizeForEncoding(MCStreamer &streamer, } } -static void EmitSymbol(MCStreamer &streamer, const MCSymbol &symbol, - unsigned symbolEncoding, const char *comment = 0) { +static void EmitFDESymbol(MCStreamer &streamer, const MCSymbol &symbol, + unsigned symbolEncoding, bool isEH, + const char *comment = 0) { MCContext &context = streamer.getContext(); const MCAsmInfo *asmInfo = context.getAsmInfo(); const MCExpr *v = asmInfo->getExprForFDESymbol(&symbol, @@ -848,7 +849,10 @@ static void EmitSymbol(MCStreamer &streamer, const MCSymbol &symbol, streamer); unsigned size = getSizeForEncoding(streamer, symbolEncoding); if (streamer.isVerboseAsm() && comment) streamer.AddComment(comment); - streamer.EmitAbsValue(v, size); + if (asmInfo->doDwarfFDESymbolsUseAbsDiff() && isEH) + streamer.EmitAbsValue(v, size); + else + streamer.EmitValue(v, size); } static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol, @@ -1347,7 +1351,7 @@ MCSymbol *FrameEmitterImpl::EmitFDE(MCStreamer &streamer, unsigned PCEncoding = IsEH ? MOFI->getFDEEncoding(UsingCFI) : (unsigned)dwarf::DW_EH_PE_absptr; unsigned PCSize = getSizeForEncoding(streamer, PCEncoding); - EmitSymbol(streamer, *frame.Begin, PCEncoding, "FDE initial location"); + EmitFDESymbol(streamer, *frame.Begin, PCEncoding, IsEH, "FDE initial location"); // PC Range const MCExpr *Range = MakeStartMinusEndExpr(streamer, *frame.Begin, @@ -1367,8 +1371,8 @@ MCSymbol *FrameEmitterImpl::EmitFDE(MCStreamer &streamer, // Augmentation Data if (frame.Lsda) - EmitSymbol(streamer, *frame.Lsda, frame.LsdaEncoding, - "Language Specific Data Area"); + EmitFDESymbol(streamer, *frame.Lsda, frame.LsdaEncoding, true, + "Language Specific Data Area"); } // Call Frame Instructions |
