//===-- llvm/CodeGen/TargetLoweringObjectFileImpl.cpp - Object File Info --===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file implements classes used to handle lowerings specific to common // object file formats. // //===----------------------------------------------------------------------===// #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h" #include "llvm/Constants.h" #include "llvm/DerivedTypes.h" #include "llvm/Function.h" #include "llvm/GlobalVariable.h" #include "llvm/Module.h" #include "llvm/CodeGen/MachineModuleInfoImpls.h" #include "llvm/MC/MCContext.h" #include "llvm/MC/MCExpr.h" #include "llvm/MC/MCSectionMachO.h" #include "llvm/MC/MCSectionELF.h" #include "llvm/MC/MCSectionCOFF.h" #include "llvm/MC/MCStreamer.h" #include "llvm/MC/MCSymbol.h" #include "llvm/Target/Mangler.h" #include "llvm/DataLayout.h" #include "llvm/Target/TargetMachine.h" #include "llvm/Target/TargetOptions.h" #include "llvm/Support/Dwarf.h" #include "llvm/Support/ELF.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/raw_ostream.h" #include "llvm/ADT/SmallString.h" #include "llvm/ADT/StringExtras.h" #include "llvm/ADT/Triple.h" using namespace llvm; using namespace dwarf; //===----------------------------------------------------------------------===// // ELF //===----------------------------------------------------------------------===// MCSymbol * TargetLoweringObjectFileELF::getCFIPersonalitySymbol(const GlobalValue *GV, Mangler *Mang, MachineModuleInfo *MMI) const { unsigned Encoding = getPersonalityEncoding(); switch (Encoding & 0x70) { default: report_fatal_error("We do not support this DWARF encoding yet!"); case dwarf::DW_EH_PE_absptr: return Mang->getSymbol(GV); case dwarf::DW_EH_PE_pcrel: { return getContext().GetOrCreateSymbol(StringRef("DW.ref.") + Mang->getSymbol(GV)->getName()); } } } void TargetLoweringObjectFileELF::emitPersonalityValue(MCStreamer &Streamer, const TargetMachine &TM, const MCSymbol *Sym) const { SmallString<64> NameData("DW.ref."); NameData += Sym->getName(); MCSymbol *Label = getContext().GetOrCreateSymbol(NameData); Streamer.EmitSymbolAttribute(Label, MCSA_Hidden); Streamer.EmitSymbolAttribute(Label, MCSA_Weak); StringRef Prefix = ".data."; NameData.insert(NameData.begin(), Prefix.begin(), Prefix.end()); unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_GROUP; const MCSection *Sec = getContext().getELFSection(NameData, ELF::SHT_PROGBITS, Flags, SectionKind::getDataRel(), 0, Label->getName()); unsigned Size = TM.getDataLayout()->getPointerSize(0); Streamer.SwitchSection(Sec); Streamer.EmitValueToAlignment(TM.getDataLayout()->getPointerABIAlignment(0)); Streamer.EmitSymbolAttribute(Label, MCSA_ELF_TypeObject); const MCExpr *E = MCConstantExpr::Create(Size, getContext()); Streamer.EmitELFSize(Label, E); Streamer.EmitLabel(Label); Streamer.EmitSymbolValue(Sym, Size); } static SectionKind getELFKindForNamedSection(StringRef Name, SectionKind K) { // N.B.: The defaults used in here are no the same ones used in MC. // We follow gcc, MC follows gas. For example, given ".section .eh_frame", // both gas and MC will produce a section with no flags. Given // section(".eh_frame") gcc will produce: // // .section .eh_frame,"a",@progbits if (Name.empty() || Name[0] != '.') return K; // Some lame default implementation based on some magic section names. if (Name == ".bss" || Name.startswith(".bss.") || Name.startswith(".gnu.linkonce.b.") || Name.startswith(".llvm.linkonce.b.") || Name == ".sbss" || Name.startswith(".sbss.") || Name.startswith(".gnu.linkonce.sb.") || Name.startswith(".llvm.linkonce.sb.")) return SectionKind::getBSS(); if (Name == ".tdata" || Name.startswith(".tdata.") || Name.startswith(".gnu.linkonce.td.") || Name.startswith(".llvm.linkonce.td.")) return SectionKind::getThreadData(); if (Name == ".tbss" || Name.startswith(".tbss.") || Name.startswith(".gnu.linkonce.tb.") || Name.startswith(".llvm.linkonce.tb.")) return SectionKind::getThreadBSS(); return K; } static unsigned getELFSectionType(StringRef Name, SectionKind K) { if (Name == ".init_array") return ELF::SHT_INIT_ARRAY; if (Name == ".fini_array") return ELF::SHT_FINI_ARRAY; if (Name == ".preinit_array") return ELF::SHT_PREINIT_ARRAY; if (K.isBSS() || K.isThreadBSS()) return ELF::SHT_NOBITS; return ELF::SHT_PROGBITS; } static unsigned getELFSectionFlags(SectionKind K) { unsigned Flags = 0; if (!K.isMetadata()) Flags |= ELF::SHF_ALLOC; if (K.isText()) Flags |= ELF::SHF_EXECINSTR; if (K.isWriteable()) Flags |= ELF::SHF_WRITE; if (K.isThreadLocal()) Flags |= ELF::SHF_TLS; // K.isMergeableConst() is left out to honour PR4650 if (K.isMergeableCString() || K.isMergeableConst4() || K.isMergeableConst8() || K.isMergeableConst16()) Flags |= ELF::SHF_MERGE; if (K.isMergeableCString()) Flags |= ELF::SHF_STRINGS; return Flags; } const MCSection *TargetLoweringObjectFileELF:: getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, Mangler *Mang, const TargetMachine &TM) const { StringRef SectionName = GV->getSection(); // Infer section flags from the section name if we can. Kind = getELFKindForNamedSection(SectionName, Kind); return getContext().getELFSection(SectionName, getELFSectionType(SectionName, Kind), getELFSectionFlags(Kind), Kind); } /// getSectionPrefixForGlobal - Return the section prefix name used by options /// FunctionsSections and DataSections. static const char *getSectionPrefixForGlobal(SectionKind Kind) { if (Kind.isText()) return ".text."; if (Kind.isReadOnly()) return ".rodata."; if (Kind.isBSS()) return ".bss."; if (Kind.isThreadData()) return ".tdata."; if (Kind.isThreadBSS()) return ".tbss."; if (Kind.isDataNoRel()) return ".data."; if (Kind.isDataRelLocal()) return ".data.rel.local."; if (Kind.isDataRel()) return ".data.rel."; if (Kind.isReadOnlyWithRelLocal()) return ".data.rel.ro.local."; assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); return ".data.rel.ro."; } const MCSection *TargetLoweringObjectFileELF:: SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, Mangler *Mang, const TargetMachine &TM) const { // If we have -ffunction-section or -fdata-section then we should emit the // global value to a uniqued section specifically for it. bool EmitUniquedSection; if (Kind.isText()) EmitUniquedSection = TM.getFunctionSections(); else EmitUniquedSection = TM.getDataSections(); // If this global is linkonce/weak and the target handles this by emitting it // into a 'uniqued' section name, create and return the section now. if ((GV->isWeakForLinker() || EmitUniquedSection) && !Kind.isCommon()) { const char *Prefix; Prefix = getSectionPrefixForGlobal(Kind); SmallString<128> Name(Prefix, Prefix+strlen(Prefix)); MCSymbol *Sym = Mang->getSymbol(GV); Name.append(Sym->getName().begin(), Sym->getName().end()); StringRef Group = ""; unsigned Flags = getELFSectionFlags(Kind); if (GV->isWeakForLinker()) { Group = Sym->getName(); Flags |= ELF::SHF_GROUP; } return getContext().getELFSection(Name.str(), getELFSectionType(Name.str(), Kind), Flags, Kind, 0, Group); } if (Kind.isText()) return TextSection; if (Kind.isMergeable1ByteCString() || Kind.isMergeable2ByteCString() || Kind.isMergeable4ByteCString()) { // We also need alignment here. // FIXME: this is getting the alignment of the character, not the // alignment of the global! unsigned Align = TM.getDataLayout()->getPreferredAlignment(cast(GV)); const char *SizeSpec = ".rodata.str1."; if (Kind.isMergeable2ByteCString()) SizeSpec = ".rodata.str2."; else if (Kind.isMergeable4ByteCString()) SizeSpec = ".rodata.str4."; else assert(Kind.isMergeable1ByteCString() && "unknown string width"); std::string Name = SizeSpec + utostr(Align); return getContext().getELFSection(Name, ELF::SHT_PROGBITS, ELF::SHF_ALLOC | ELF::SHF_MERGE | ELF::SHF_STRINGS, Kind); } if (Kind.isMergeableConst()) { if (Kind.isMergeableConst4() && MergeableConst4Section) return MergeableConst4Section; if (Kind.isMergeableConst8() && MergeableConst8Section) return MergeableConst8Section; if (Kind.isMergeableConst16() && MergeableConst16Section) return MergeableConst16Section; return ReadOnlySection; // .const } if (Kind.isReadOnly()) return ReadOnlySection; if (Kind.isThreadData()) return TLSDataSection; if (Kind.isThreadBSS()) return TLSBSSSection; // Note: we claim that common symbols are put in BSSSection, but they are // really emitted with the magic .comm directive, which creates a symbol table // entry but not a section. if (Kind.isBSS() || Kind.isCommon()) return BSSSection; if (Kind.isDataNoRel()) return DataSection; if (Kind.isDataRelLocal()) return DataRelLocalSection; if (Kind.isDataRel()) return DataRelSection; if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); return DataRelROSection; } /// getSectionForConstant - Given a mergeable constant with the /// specified size and relocation information, return a section that it /// should be placed in. const MCSection *TargetLoweringObjectFileELF:: getSectionForConstant(SectionKind Kind) const { if (Kind.isMergeableConst4() && MergeableConst4Section) return MergeableConst4Section; if (Kind.isMergeableConst8() && MergeableConst8Section) return MergeableConst8Section; if (Kind.isMergeableConst16() && MergeableConst16Section) return MergeableConst16Section; if (Kind.isReadOnly()) return ReadOnlySection; if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); return DataRelROSection; } const MCExpr *TargetLoweringObjectFileELF:: getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang, MachineModuleInfo *MMI, unsigned Encoding, MCStreamer &Streamer) const { if (Encoding & dwarf::DW_EH_PE_indirect) { MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo(); SmallString<128> Name; Mang->getNameWithPrefix(Name, GV, true); Name += ".DW.stub"; // Add information about the stub reference to ELFMMI so that the stub // gets emitted by the asmprinter. MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str()); MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym); if (StubSym.getPointer() == 0) { MCSymbol *Sym = Mang->getSymbol(GV); StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); } return TargetLoweringObjectFile:: getExprForDwarfReference(SSym, Encoding & ~dwarf::DW_EH_PE_indirect, Streamer); } return TargetLoweringObjectFile:: getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer); } const MCSection * TargetLoweringObjectFileELF::getStaticCtorSection(unsigned Priority) const { // The default scheme is .ctor / .dtor, so we have to invert the priority // numbering. if (Priority == 65535) return StaticCtorSection; if (UseInitArray) { std::string Name = std::string(".init_array.") + utostr(Priority); return getContext().getELFSection(Name, ELF::SHT_INIT_ARRAY, ELF::SHF_ALLOC | ELF::SHF_WRITE, SectionKind::getDataRel()); } else { std::string Name = std::string(".ctors.") + utostr(65535 - Priority); return getContext().getELFSection(Name, ELF::SHT_PROGBITS, ELF::SHF_ALLOC |ELF::SHF_WRITE, SectionKind::getDataRel()); } } const MCSection * TargetLoweringObjectFileELF::getStaticDtorSection(unsigned Priority) const { // The default scheme is .ctor / .dtor, so we have to invert the priority // numbering. if (Priority == 65535) return StaticDtorSection; if (UseInitArray) { std::string Name = std::string(".fini_array.") + utostr(Priority); return getContext().getELFSection(Name, ELF::SHT_FINI_ARRAY, ELF::SHF_ALLOC | ELF::SHF_WRITE, SectionKind::getDataRel()); } else { std::string Name = std::string(".dtors.") + utostr(65535 - Priority); return getContext().getELFSection(Name, ELF::SHT_PROGBITS, ELF::SHF_ALLOC |ELF::SHF_WRITE, SectionKind::getDataRel()); } } void TargetLoweringObjectFileELF::InitializeELF(bool UseInitArray_) { UseInitArray = UseInitArray_; if (!UseInitArray) return; StaticCtorSection = getContext().getELFSection(".init_array", ELF::SHT_INIT_ARRAY, ELF::SHF_WRITE | ELF::SHF_ALLOC, SectionKind::getDataRel()); StaticDtorSection = getContext().getELFSection(".fini_array", ELF::SHT_FINI_ARRAY, ELF::SHF_WRITE | ELF::SHF_ALLOC, SectionKind::getDataRel()); } //===----------------------------------------------------------------------===// // MachO //===----------------------------------------------------------------------===// /// emitModuleFlags - Emit the module flags that specify the garbage collection /// information. void TargetLoweringObjectFileMachO:: emitModuleFlags(MCStreamer &Streamer, ArrayRef ModuleFlags, Mangler *Mang, const TargetMachine &TM) const { unsigned VersionVal = 0; unsigned ImageInfoFlags = 0; StringRef SectionVal; for (ArrayRef::iterator i = ModuleFlags.begin(), e = ModuleFlags.end(); i != e; ++i) { const Module::ModuleFlagEntry &MFE = *i; // Ignore flags with 'Require' behavior. if (MFE.Behavior == Module::Require) continue; StringRef Key = MFE.Key->getString(); Value *Val = MFE.Val; if (Key == "Objective-C Image Info Version") VersionVal = cast(Val)->getZExtValue(); else if (Key == "Objective-C Garbage Collection" || Key == "Objective-C GC Only" || Key == "Objective-C Is Simulated") ImageInfoFlags |= cast(Val)->getZExtValue(); else if (Key == "Objective-C Image Info Section") SectionVal = cast(Val)->getString(); } // The section is mandatory. If we don't have it, then we don't have GC info. if (SectionVal.empty()) return; StringRef Segment, Section; unsigned TAA = 0, StubSize = 0; bool TAAParsed; std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(SectionVal, Segment, Section, TAA, TAAParsed, StubSize); if (!ErrorCode.empty()) // If invalid, report the error with report_fatal_error. report_fatal_error("Invalid section specifier '" + Section + "': " + ErrorCode + "."); // Get the section. const MCSectionMachO *S = getContext().getMachOSection(Segment, Section, TAA, StubSize, SectionKind::getDataNoRel()); Streamer.SwitchSection(S); Streamer.EmitLabel(getContext(). GetOrCreateSymbol(StringRef("L_OBJC_IMAGE_INFO"))); Streamer.EmitIntValue(VersionVal, 4); Streamer.EmitIntValue(ImageInfoFlags, 4); Streamer.AddBlankLine(); } const MCSection *TargetLoweringObjectFileMachO:: getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, Mangler *Mang, const TargetMachine &TM) const { // Parse the section specifier and create it if valid. StringRef Segment, Section; unsigned TAA = 0, StubSize = 0; bool TAAParsed; std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section, TAA, TAAParsed, StubSize); if (!ErrorCode.empty()) { // If invalid, report the error with report_fatal_error. report_fatal_error("Global variable '" + GV->getName() + "' has an invalid section specifier '" + GV->getSection() + "': " + ErrorCode + "."); } // Get the section. const MCSectionMachO *S = getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind); // If TAA wasn't set by ParseSectionSpecifier() above, // use the value returned by getMachOSection() as a default. if (!TAAParsed) TAA = S->getTypeAndAttributes(); // Okay, now that we got the section, verify that the TAA & StubSize agree. // If the user declared multiple globals with different section flags, we need // to reject it here. if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) { // If invalid, report the error with report_fatal_error. report_fatal_error("Global variable '" + GV->getName() + "' section type or attributes does not match previous" " section specifier"); } return S; } const MCSection *TargetLoweringObjectFileMachO:: SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, Mangler *Mang, const TargetMachine &TM) const { // Handle thread local data. if (Kind.isThreadBSS()) return TLSBSSSection; if (Kind.isThreadData()) return TLSDataSection; if (Kind.isText()) return GV->isWeakForLinker() ? TextCoalSection : TextSection; // If this is weak/linkonce, put this in a coalescable section, either in text // or data depending on if it is writable. if (GV->isWeakForLinker()) { if (Kind.isReadOnly()) return ConstTextCoalSection; return DataCoalSection; } // FIXME: Alignment check should be handled by section classifier. if (Kind.isMergeable1ByteCString() && TM.getDataLayout()->getPreferredAlignment(cast(GV)) < 32) return CStringSection; // Do not put 16-bit arrays in the UString section if they have an // externally visible label, this runs into issues with certain linker // versions. if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() && TM.getDataLayout()->getPreferredAlignment(cast(GV)) < 32) return UStringSection; if (Kind.isMergeableConst()) { if (Kind.isMergeableConst4()) return FourByteConstantSection; if (Kind.isMergeableConst8()) return EightByteConstantSection; if (Kind.isMergeableConst16() && SixteenByteConstantSection) return SixteenByteConstantSection; } // Otherwise, if it is readonly, but not something we can specially optimize, // just drop it in .const. if (Kind.isReadOnly()) return ReadOnlySection; // If this is marked const, put it into a const section. But if the dynamic // linker needs to write to it, put it in the data segment. if (Kind.isReadOnlyWithRel()) return ConstDataSection; // Put zero initialized globals with strong external linkage in the // DATA, __common section with the .zerofill directive. if (Kind.isBSSExtern()) return DataCommonSection; // Put zero initialized globals with local linkage in __DATA,__bss directive // with the .zerofill directive (aka .lcomm). if (Kind.isBSSLocal()) return DataBSSSection; // Otherwise, just drop the variable in the normal data section. return DataSection; } const MCSection * TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const { // If this constant requires a relocation, we have to put it in the data // segment, not in the text segment. if (Kind.isDataRel() || Kind.isReadOnlyWithRel()) return ConstDataSection; if (Kind.isMergeableConst4()) return FourByteConstantSection; if (Kind.isMergeableConst8()) return EightByteConstantSection; if (Kind.isMergeableConst16() && SixteenByteConstantSection) return SixteenByteConstantSection; return ReadOnlySection; // .const } /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide /// not to emit the UsedDirective for some symbols in llvm.used. // FIXME: REMOVE this (rdar://7071300) bool TargetLoweringObjectFileMachO:: shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const { /// On Darwin, internally linked data beginning with "L" or "l" does not have /// the directive emitted (this occurs in ObjC metadata). if (!GV) return false; // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix. if (GV->hasLocalLinkage() && !isa(GV)) { // FIXME: ObjC metadata is currently emitted as internal symbols that have // \1L and \0l prefixes on them. Fix them to be Private/LinkerPrivate and // this horrible hack can go away. MCSymbol *Sym = Mang->getSymbol(GV); if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l') return false; } return true; } const MCExpr *TargetLoweringObjectFileMachO:: getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang, MachineModuleInfo *MMI, unsigned Encoding, MCStreamer &Streamer) const { // The mach-o version of this method defaults to returning a stub reference. if (Encoding & DW_EH_PE_indirect) { MachineModuleInfoMachO &MachOMMI = MMI->getObjFileInfo(); SmallString<128> Name; Mang->getNameWithPrefix(Name, GV, true); Name += "$non_lazy_ptr"; // Add information about the stub reference to MachOMMI so that the stub // gets emitted by the asmprinter. MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str()); MachineModuleInfoImpl::StubValueTy &StubSym = GV->hasHiddenVisibility() ? MachOMMI.getHiddenGVStubEntry(SSym) : MachOMMI.getGVStubEntry(SSym); if (StubSym.getPointer() == 0) { MCSymbol *Sym = Mang->getSymbol(GV); StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); } return TargetLoweringObjectFile:: getExprForDwarfReference(SSym, Encoding & ~dwarf::DW_EH_PE_indirect, Streamer); } return TargetLoweringObjectFile:: getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer); } MCSymbol *TargetLoweringObjectFileMachO:: getCFIPersonalitySymbol(const GlobalValue *GV, Mangler *Mang, MachineModuleInfo *MMI) const { // The mach-o version of this method defaults to returning a stub reference. MachineModuleInfoMachO &MachOMMI = MMI->getObjFileInfo(); SmallString<128> Name; Mang->getNameWithPrefix(Name, GV, true); Name += "$non_lazy_ptr"; // Add information about the stub reference to MachOMMI so that the stub // gets emitted by the asmprinter. MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str()); MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym); if (StubSym.getPointer() == 0) { MCSymbol *Sym = Mang->getSymbol(GV); StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); } return SSym; } //===----------------------------------------------------------------------===// // COFF //===----------------------------------------------------------------------===// static unsigned getCOFFSectionFlags(SectionKind K) { unsigned Flags = 0; if (K.isMetadata()) Flags |= COFF::IMAGE_SCN_MEM_DISCARDABLE; else if (K.isText()) Flags |= COFF::IMAGE_SCN_MEM_EXECUTE | COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_CNT_CODE; else if (K.isBSS ()) Flags |= COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_MEM_WRITE; else if (K.isThreadLocal()) Flags |= COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_MEM_WRITE; else if (K.isReadOnly()) Flags |= COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ; else if (K.isWriteable()) Flags |= COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_MEM_WRITE; return Flags; } const MCSection *TargetLoweringObjectFileCOFF:: getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, Mangler *Mang, const TargetMachine &TM) const { return getContext().getCOFFSection(GV->getSection(), getCOFFSectionFlags(Kind), Kind); } static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) { if (Kind.isText()) return ".text$"; if (Kind.isBSS ()) return ".bss$"; if (Kind.isThreadLocal()) return ".tls$"; if (Kind.isWriteable()) return ".data$"; return ".rdata$"; } const MCSection *TargetLoweringObjectFileCOFF:: SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, Mangler *Mang, const TargetMachine &TM) const { // If this global is linkonce/weak and the target handles this by emitting it // into a 'uniqued' section name, create and return the section now. if (GV->isWeakForLinker()) { const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind); SmallString<128> Name(Prefix, Prefix+strlen(Prefix)); MCSymbol *Sym = Mang->getSymbol(GV); Name.append(Sym->getName().begin() + 1, Sym->getName().end()); unsigned Characteristics = getCOFFSectionFlags(Kind); Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT; return getContext().getCOFFSection(Name.str(), Characteristics, COFF::IMAGE_COMDAT_SELECT_ANY, Kind); } if (Kind.isText()) return getTextSection(); if (Kind.isThreadLocal()) return getTLSDataSection(); return getDataSection(); }