//===-- 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/ADT/SmallString.h" #include "llvm/ADT/StringExtras.h" #include "llvm/ADT/Triple.h" #include "llvm/CodeGen/MachineModuleInfoImpls.h" #include "llvm/IR/Constants.h" #include "llvm/IR/DataLayout.h" #include "llvm/IR/DerivedTypes.h" #include "llvm/IR/Function.h" #include "llvm/IR/GlobalVariable.h" #include "llvm/IR/Mangler.h" #include "llvm/IR/Module.h" #include "llvm/MC/MCContext.h" #include "llvm/MC/MCExpr.h" #include "llvm/MC/MCSectionCOFF.h" #include "llvm/MC/MCSectionELF.h" #include "llvm/MC/MCSectionMachO.h" #include "llvm/MC/MCStreamer.h" #include "llvm/MC/MCSymbol.h" #include "llvm/MC/MCValue.h" #include "llvm/Support/Dwarf.h" #include "llvm/Support/ELF.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/raw_ostream.h" #include "llvm/Target/TargetLowering.h" #include "llvm/Target/TargetMachine.h" #include "llvm/Target/TargetSubtargetInfo.h" using namespace llvm; using namespace dwarf; //===----------------------------------------------------------------------===// // ELF //===----------------------------------------------------------------------===// MCSymbol *TargetLoweringObjectFileELF::getCFIPersonalitySymbol( const GlobalValue *GV, Mangler &Mang, const TargetMachine &TM, MachineModuleInfo *MMI) const { unsigned Encoding = getPersonalityEncoding(); if ((Encoding & 0x80) == dwarf::DW_EH_PE_indirect) return getContext().GetOrCreateSymbol(StringRef("DW.ref.") + TM.getSymbol(GV, Mang)->getName()); if ((Encoding & 0x70) == dwarf::DW_EH_PE_absptr) return TM.getSymbol(GV, Mang); report_fatal_error("We do not support this DWARF encoding yet!"); } 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, 0, Label->getName()); unsigned Size = TM.getDataLayout()->getPointerSize(); Streamer.SwitchSection(Sec); Streamer.EmitValueToAlignment(TM.getDataLayout()->getPointerABIAlignment()); Streamer.EmitSymbolAttribute(Label, MCSA_ELF_TypeObject); const MCExpr *E = MCConstantExpr::Create(Size, getContext()); Streamer.EmitELFSize(Label, E); Streamer.EmitLabel(Label); Streamer.EmitSymbolValue(Sym, Size); } const MCExpr *TargetLoweringObjectFileELF::getTTypeGlobalReference( const GlobalValue *GV, unsigned Encoding, Mangler &Mang, const TargetMachine &TM, MachineModuleInfo *MMI, MCStreamer &Streamer) const { if (Encoding & dwarf::DW_EH_PE_indirect) { MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo(); MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, ".DW.stub", Mang, TM); // Add information about the stub reference to ELFMMI so that the stub // gets emitted by the asmprinter. MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym); if (!StubSym.getPointer()) { MCSymbol *Sym = TM.getSymbol(GV, Mang); StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); } return TargetLoweringObjectFile:: getTTypeReference(MCSymbolRefExpr::Create(SSym, getContext()), Encoding & ~dwarf::DW_EH_PE_indirect, Streamer); } return TargetLoweringObjectFile:: getTTypeGlobalReference(GV, Encoding, Mang, TM, MMI, Streamer); } 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; if (K.isMergeableCString() || K.isMergeableConst()) Flags |= ELF::SHF_MERGE; if (K.isMergeableCString()) Flags |= ELF::SHF_STRINGS; return Flags; } static const Comdat *getELFComdat(const GlobalValue *GV) { const Comdat *C = GV->getComdat(); if (!C) return nullptr; if (C->getSelectionKind() != Comdat::Any) report_fatal_error("ELF COMDATs only support SelectionKind::Any, '" + C->getName() + "' cannot be lowered."); return C; } 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); StringRef Group = ""; unsigned Flags = getELFSectionFlags(Kind); if (const Comdat *C = getELFComdat(GV)) { Group = C->getName(); Flags |= ELF::SHF_GROUP; } return getContext().getELFSection(SectionName, getELFSectionType(SectionName, Kind), Flags, /*EntrySize=*/0, Group); } /// Return the section prefix name used by options FunctionsSections and /// DataSections. static StringRef 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"; } static const MCSectionELF *selectELFSectionForGlobal( MCContext &Ctx, const GlobalValue *GV, SectionKind Kind, Mangler &Mang, const TargetMachine &TM, bool EmitUniqueSection, unsigned Flags) { unsigned EntrySize = 0; if (Kind.isMergeableCString()) { if (Kind.isMergeable2ByteCString()) { EntrySize = 2; } else if (Kind.isMergeable4ByteCString()) { EntrySize = 4; } else { EntrySize = 1; assert(Kind.isMergeable1ByteCString() && "unknown string width"); } } else if (Kind.isMergeableConst()) { if (Kind.isMergeableConst4()) { EntrySize = 4; } else if (Kind.isMergeableConst8()) { EntrySize = 8; } else { assert(Kind.isMergeableConst16() && "unknown data width"); EntrySize = 16; } } StringRef Group = ""; if (const Comdat *C = getELFComdat(GV)) { Flags |= ELF::SHF_GROUP; Group = C->getName(); } bool UniqueSectionNames = TM.getUniqueSectionNames(); SmallString<128> Name; if (Kind.isMergeableCString()) { // 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)); std::string SizeSpec = ".rodata.str" + utostr(EntrySize) + "."; Name = SizeSpec + utostr(Align); } else if (Kind.isMergeableConst()) { Name = ".rodata.cst"; Name += utostr(EntrySize); } else { Name = getSectionPrefixForGlobal(Kind); } if (EmitUniqueSection && UniqueSectionNames) { Name.push_back('.'); TM.getNameWithPrefix(Name, GV, Mang, true); } return Ctx.getELFSection(Name, getELFSectionType(Name, Kind), Flags, EntrySize, Group, EmitUniqueSection && !UniqueSectionNames); } const MCSection *TargetLoweringObjectFileELF::SelectSectionForGlobal( const GlobalValue *GV, SectionKind Kind, Mangler &Mang, const TargetMachine &TM) const { unsigned Flags = getELFSectionFlags(Kind); // If we have -ffunction-section or -fdata-section then we should emit the // global value to a uniqued section specifically for it. bool EmitUniqueSection = false; if (!(Flags & ELF::SHF_MERGE) && !Kind.isCommon()) { if (Kind.isText()) EmitUniqueSection = TM.getFunctionSections(); else EmitUniqueSection = TM.getDataSections(); } EmitUniqueSection |= GV->hasComdat(); return selectELFSectionForGlobal(getContext(), GV, Kind, Mang, TM, EmitUniqueSection, Flags); } const MCSection *TargetLoweringObjectFileELF::getSectionForJumpTable( const Function &F, Mangler &Mang, const TargetMachine &TM) const { // If the function can be removed, produce a unique section so that // the table doesn't prevent the removal. const Comdat *C = F.getComdat(); bool EmitUniqueSection = TM.getFunctionSections() || C; if (!EmitUniqueSection) return ReadOnlySection; return selectELFSectionForGlobal(getContext(), &F, SectionKind::getReadOnly(), Mang, TM, EmitUniqueSection, ELF::SHF_ALLOC); } bool TargetLoweringObjectFileELF::shouldPutJumpTableInFunctionSection( bool UsesLabelDifference, const Function &F) const { // We can always create relative relocations, so use another section // that can be marked non-executable. return false; } /// 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 Constant *C) 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; } static const MCSectionELF *getStaticStructorSection(MCContext &Ctx, bool UseInitArray, bool IsCtor, unsigned Priority, const MCSymbol *KeySym) { std::string Name; unsigned Type; unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_WRITE; StringRef COMDAT = KeySym ? KeySym->getName() : ""; if (KeySym) Flags |= ELF::SHF_GROUP; if (UseInitArray) { if (IsCtor) { Type = ELF::SHT_INIT_ARRAY; Name = ".init_array"; } else { Type = ELF::SHT_FINI_ARRAY; Name = ".fini_array"; } if (Priority != 65535) { Name += '.'; Name += utostr(Priority); } } else { // The default scheme is .ctor / .dtor, so we have to invert the priority // numbering. if (IsCtor) Name = ".ctors"; else Name = ".dtors"; if (Priority != 65535) { Name += '.'; Name += utostr(65535 - Priority); } Type = ELF::SHT_PROGBITS; } return Ctx.getELFSection(Name, Type, Flags, 0, COMDAT); } const MCSection *TargetLoweringObjectFileELF::getStaticCtorSection( unsigned Priority, const MCSymbol *KeySym) const { return getStaticStructorSection(getContext(), UseInitArray, true, Priority, KeySym); } const MCSection *TargetLoweringObjectFileELF::getStaticDtorSection( unsigned Priority, const MCSymbol *KeySym) const { return getStaticStructorSection(getContext(), UseInitArray, false, Priority, KeySym); } 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); StaticDtorSection = getContext().getELFSection( ".fini_array", ELF::SHT_FINI_ARRAY, ELF::SHF_WRITE | ELF::SHF_ALLOC); } //===----------------------------------------------------------------------===// // MachO //===----------------------------------------------------------------------===// TargetLoweringObjectFileMachO::TargetLoweringObjectFileMachO() : TargetLoweringObjectFile() { SupportIndirectSymViaGOTPCRel = true; } /// getDepLibFromLinkerOpt - Extract the dependent library name from a linker /// option string. Returns StringRef() if the option does not specify a library. StringRef TargetLoweringObjectFileMachO:: getDepLibFromLinkerOpt(StringRef LinkerOption) const { const char *LibCmd = "-l"; if (LinkerOption.startswith(LibCmd)) return LinkerOption.substr(strlen(LibCmd)); return StringRef(); } /// emitModuleFlags - Perform code emission for module flags. void TargetLoweringObjectFileMachO:: emitModuleFlags(MCStreamer &Streamer, ArrayRef ModuleFlags, Mangler &Mang, const TargetMachine &TM) const { unsigned VersionVal = 0; unsigned ImageInfoFlags = 0; MDNode *LinkerOptions = nullptr; 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(); Metadata *Val = MFE.Val; if (Key == "Objective-C Image Info Version") { VersionVal = mdconst::extract(Val)->getZExtValue(); } else if (Key == "Objective-C Garbage Collection" || Key == "Objective-C GC Only" || Key == "Objective-C Is Simulated" || Key == "Objective-C Image Swift Version") { ImageInfoFlags |= mdconst::extract(Val)->getZExtValue(); } else if (Key == "Objective-C Image Info Section") { SectionVal = cast(Val)->getString(); } else if (Key == "Linker Options") { LinkerOptions = cast(Val); } } // Emit the linker options if present. if (LinkerOptions) { for (unsigned i = 0, e = LinkerOptions->getNumOperands(); i != e; ++i) { MDNode *MDOptions = cast(LinkerOptions->getOperand(i)); SmallVector StrOptions; // Convert to strings. for (unsigned ii = 0, ie = MDOptions->getNumOperands(); ii != ie; ++ii) { MDString *MDOption = cast(MDOptions->getOperand(ii)); StrOptions.push_back(MDOption->getString()); } Streamer.EmitLinkerOptions(StrOptions); } } // 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(); } static void checkMachOComdat(const GlobalValue *GV) { const Comdat *C = GV->getComdat(); if (!C) return; report_fatal_error("MachO doesn't support COMDATs, '" + C->getName() + "' cannot be lowered."); } 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; checkMachOComdat(GV); 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 { checkMachOComdat(GV); // 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; // With MachO only variables whose corresponding symbol starts with 'l' or // 'L' can be merged, so we only try merging GVs with private linkage. if (GV->hasPrivateLinkage() && Kind.isMergeableConst()) { if (Kind.isMergeableConst4()) return FourByteConstantSection; if (Kind.isMergeableConst8()) return EightByteConstantSection; if (Kind.isMergeableConst16()) 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 Constant *C) 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()) return SixteenByteConstantSection; return ReadOnlySection; // .const } const MCExpr *TargetLoweringObjectFileMachO::getTTypeGlobalReference( const GlobalValue *GV, unsigned Encoding, Mangler &Mang, const TargetMachine &TM, MachineModuleInfo *MMI, 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(); MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr", Mang, TM); // Add information about the stub reference to MachOMMI so that the stub // gets emitted by the asmprinter. MachineModuleInfoImpl::StubValueTy &StubSym = GV->hasHiddenVisibility() ? MachOMMI.getHiddenGVStubEntry(SSym) : MachOMMI.getGVStubEntry(SSym); if (!StubSym.getPointer()) { MCSymbol *Sym = TM.getSymbol(GV, Mang); StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); } return TargetLoweringObjectFile:: getTTypeReference(MCSymbolRefExpr::Create(SSym, getContext()), Encoding & ~dwarf::DW_EH_PE_indirect, Streamer); } return TargetLoweringObjectFile::getTTypeGlobalReference(GV, Encoding, Mang, TM, MMI, Streamer); } MCSymbol *TargetLoweringObjectFileMachO::getCFIPersonalitySymbol( const GlobalValue *GV, Mangler &Mang, const TargetMachine &TM, MachineModuleInfo *MMI) const { // The mach-o version of this method defaults to returning a stub reference. MachineModuleInfoMachO &MachOMMI = MMI->getObjFileInfo(); MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr", Mang, TM); // Add information about the stub reference to MachOMMI so that the stub // gets emitted by the asmprinter. MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym); if (!StubSym.getPointer()) { MCSymbol *Sym = TM.getSymbol(GV, Mang); StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); } return SSym; } const MCExpr *TargetLoweringObjectFileMachO::getIndirectSymViaGOTPCRel( const MCSymbol *Sym, const MCValue &MV, int64_t Offset, MachineModuleInfo *MMI, MCStreamer &Streamer) const { // Although MachO 32-bit targets do not explictly have a GOTPCREL relocation // as 64-bit do, we replace the GOT equivalent by accessing the final symbol // through a non_lazy_ptr stub instead. One advantage is that it allows the // computation of deltas to final external symbols. Example: // // _extgotequiv: // .long _extfoo // // _delta: // .long _extgotequiv-_delta // // is transformed to: // // _delta: // .long L_extfoo$non_lazy_ptr-(_delta+0) // // .section __IMPORT,__pointers,non_lazy_symbol_pointers // L_extfoo$non_lazy_ptr: // .indirect_symbol _extfoo // .long 0 // MachineModuleInfoMachO &MachOMMI = MMI->getObjFileInfo(); MCContext &Ctx = getContext(); // The offset must consider the original displacement from the base symbol // since 32-bit targets don't have a GOTPCREL to fold the PC displacement. Offset = -MV.getConstant(); const MCSymbol *BaseSym = &MV.getSymB()->getSymbol(); // Access the final symbol via sym$non_lazy_ptr and generate the appropriated // non_lazy_ptr stubs. SmallString<128> Name; StringRef Suffix = "$non_lazy_ptr"; Name += DL->getPrivateGlobalPrefix(); Name += Sym->getName(); Name += Suffix; MCSymbol *Stub = Ctx.GetOrCreateSymbol(Name); MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(Stub); if (!StubSym.getPointer()) StubSym = MachineModuleInfoImpl:: StubValueTy(const_cast(Sym), true /* access indirectly */); const MCExpr *BSymExpr = MCSymbolRefExpr::Create(BaseSym, MCSymbolRefExpr::VK_None, Ctx); const MCExpr *LHS = MCSymbolRefExpr::Create(Stub, MCSymbolRefExpr::VK_None, Ctx); if (!Offset) return MCBinaryExpr::CreateSub(LHS, BSymExpr, Ctx); const MCExpr *RHS = MCBinaryExpr::CreateAdd(BSymExpr, MCConstantExpr::Create(Offset, Ctx), Ctx); return MCBinaryExpr::CreateSub(LHS, RHS, Ctx); } //===----------------------------------------------------------------------===// // 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() || K.isReadOnlyWithRel()) 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; } static const GlobalValue *getComdatGVForCOFF(const GlobalValue *GV) { const Comdat *C = GV->getComdat(); assert(C && "expected GV to have a Comdat!"); StringRef ComdatGVName = C->getName(); const GlobalValue *ComdatGV = GV->getParent()->getNamedValue(ComdatGVName); if (!ComdatGV) report_fatal_error("Associative COMDAT symbol '" + ComdatGVName + "' does not exist."); if (ComdatGV->getComdat() != C) report_fatal_error("Associative COMDAT symbol '" + ComdatGVName + "' is not a key for its COMDAT."); return ComdatGV; } static int getSelectionForCOFF(const GlobalValue *GV) { if (const Comdat *C = GV->getComdat()) { const GlobalValue *ComdatKey = getComdatGVForCOFF(GV); if (const auto *GA = dyn_cast(ComdatKey)) ComdatKey = GA->getBaseObject(); if (ComdatKey == GV) { switch (C->getSelectionKind()) { case Comdat::Any: return COFF::IMAGE_COMDAT_SELECT_ANY; case Comdat::ExactMatch: return COFF::IMAGE_COMDAT_SELECT_EXACT_MATCH; case Comdat::Largest: return COFF::IMAGE_COMDAT_SELECT_LARGEST; case Comdat::NoDuplicates: return COFF::IMAGE_COMDAT_SELECT_NODUPLICATES; case Comdat::SameSize: return COFF::IMAGE_COMDAT_SELECT_SAME_SIZE; } } else { return COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE; } } else if (GV->isWeakForLinker()) { return COFF::IMAGE_COMDAT_SELECT_ANY; } return 0; } const MCSection *TargetLoweringObjectFileCOFF::getExplicitSectionGlobal( const GlobalValue *GV, SectionKind Kind, Mangler &Mang, const TargetMachine &TM) const { int Selection = 0; unsigned Characteristics = getCOFFSectionFlags(Kind); StringRef Name = GV->getSection(); StringRef COMDATSymName = ""; if (GV->hasComdat()) { Selection = getSelectionForCOFF(GV); const GlobalValue *ComdatGV; if (Selection == COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) ComdatGV = getComdatGVForCOFF(GV); else ComdatGV = GV; if (!ComdatGV->hasPrivateLinkage()) { MCSymbol *Sym = TM.getSymbol(ComdatGV, Mang); COMDATSymName = Sym->getName(); Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT; } else { Selection = 0; } } return getContext().getCOFFSection(Name, Characteristics, Kind, COMDATSymName, Selection); } static const char *getCOFFSectionNameForUniqueGlobal(SectionKind Kind) { if (Kind.isText()) return ".text"; if (Kind.isBSS()) return ".bss"; if (Kind.isThreadLocal()) return ".tls$"; if (Kind.isReadOnly() || Kind.isReadOnlyWithRel()) return ".rdata"; return ".data"; } const MCSection *TargetLoweringObjectFileCOFF:: SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, Mangler &Mang, const TargetMachine &TM) const { // If we have -ffunction-sections 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 ((EmitUniquedSection && !Kind.isCommon()) || GV->hasComdat()) { const char *Name = getCOFFSectionNameForUniqueGlobal(Kind); unsigned Characteristics = getCOFFSectionFlags(Kind); Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT; int Selection = getSelectionForCOFF(GV); if (!Selection) Selection = COFF::IMAGE_COMDAT_SELECT_NODUPLICATES; const GlobalValue *ComdatGV; if (GV->hasComdat()) ComdatGV = getComdatGVForCOFF(GV); else ComdatGV = GV; if (!ComdatGV->hasPrivateLinkage()) { MCSymbol *Sym = TM.getSymbol(ComdatGV, Mang); StringRef COMDATSymName = Sym->getName(); return getContext().getCOFFSection(Name, Characteristics, Kind, COMDATSymName, Selection); } else { SmallString<256> TmpData; getNameWithPrefix(TmpData, GV, /*CannotUsePrivateLabel=*/true, Mang, TM); return getContext().getCOFFSection(Name, Characteristics, Kind, TmpData, Selection); } } if (Kind.isText()) return TextSection; if (Kind.isThreadLocal()) return TLSDataSection; if (Kind.isReadOnly() || Kind.isReadOnlyWithRel()) return ReadOnlySection; // 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; return DataSection; } void TargetLoweringObjectFileCOFF::getNameWithPrefix( SmallVectorImpl &OutName, const GlobalValue *GV, bool CannotUsePrivateLabel, Mangler &Mang, const TargetMachine &TM) const { if (GV->hasPrivateLinkage() && ((isa(GV) && TM.getFunctionSections()) || (isa(GV) && TM.getDataSections()))) CannotUsePrivateLabel = true; Mang.getNameWithPrefix(OutName, GV, CannotUsePrivateLabel); } const MCSection *TargetLoweringObjectFileCOFF::getSectionForJumpTable( const Function &F, Mangler &Mang, const TargetMachine &TM) const { // If the function can be removed, produce a unique section so that // the table doesn't prevent the removal. const Comdat *C = F.getComdat(); bool EmitUniqueSection = TM.getFunctionSections() || C; if (!EmitUniqueSection) return ReadOnlySection; // FIXME: we should produce a symbol for F instead. if (F.hasPrivateLinkage()) return ReadOnlySection; MCSymbol *Sym = TM.getSymbol(&F, Mang); StringRef COMDATSymName = Sym->getName(); SectionKind Kind = SectionKind::getReadOnly(); const char *Name = getCOFFSectionNameForUniqueGlobal(Kind); unsigned Characteristics = getCOFFSectionFlags(Kind); Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT; return getContext().getCOFFSection(Name, Characteristics, Kind, COMDATSymName, COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE); } StringRef TargetLoweringObjectFileCOFF:: getDepLibFromLinkerOpt(StringRef LinkerOption) const { const char *LibCmd = "/DEFAULTLIB:"; if (LinkerOption.startswith(LibCmd)) return LinkerOption.substr(strlen(LibCmd)); return StringRef(); } void TargetLoweringObjectFileCOFF:: emitModuleFlags(MCStreamer &Streamer, ArrayRef ModuleFlags, Mangler &Mang, const TargetMachine &TM) const { MDNode *LinkerOptions = nullptr; // Look for the "Linker Options" flag, since it's the only one we support. for (ArrayRef::iterator i = ModuleFlags.begin(), e = ModuleFlags.end(); i != e; ++i) { const Module::ModuleFlagEntry &MFE = *i; StringRef Key = MFE.Key->getString(); Metadata *Val = MFE.Val; if (Key == "Linker Options") { LinkerOptions = cast(Val); break; } } if (!LinkerOptions) return; // Emit the linker options to the linker .drectve section. According to the // spec, this section is a space-separated string containing flags for linker. const MCSection *Sec = getDrectveSection(); Streamer.SwitchSection(Sec); for (unsigned i = 0, e = LinkerOptions->getNumOperands(); i != e; ++i) { MDNode *MDOptions = cast(LinkerOptions->getOperand(i)); for (unsigned ii = 0, ie = MDOptions->getNumOperands(); ii != ie; ++ii) { MDString *MDOption = cast(MDOptions->getOperand(ii)); // Lead with a space for consistency with our dllexport implementation. std::string Directive(" "); Directive.append(MDOption->getString()); Streamer.EmitBytes(Directive); } } } const MCSection *TargetLoweringObjectFileCOFF::getStaticCtorSection( unsigned Priority, const MCSymbol *KeySym) const { return getContext().getAssociativeCOFFSection( cast(StaticCtorSection), KeySym); } const MCSection *TargetLoweringObjectFileCOFF::getStaticDtorSection( unsigned Priority, const MCSymbol *KeySym) const { return getContext().getAssociativeCOFFSection( cast(StaticDtorSection), KeySym); }