| //===-- MCMachOStreamer.cpp - MachO Streamer ------------------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/MC/MCStreamer.h" |
| #include "llvm/ADT/DenseMap.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/MC/MCAsmBackend.h" |
| #include "llvm/MC/MCAssembler.h" |
| #include "llvm/MC/MCCodeEmitter.h" |
| #include "llvm/MC/MCContext.h" |
| #include "llvm/MC/MCDwarf.h" |
| #include "llvm/MC/MCExpr.h" |
| #include "llvm/MC/MCInst.h" |
| #include "llvm/MC/MCLinkerOptimizationHint.h" |
| #include "llvm/MC/MCMachOSymbolFlags.h" |
| #include "llvm/MC/MCObjectFileInfo.h" |
| #include "llvm/MC/MCObjectStreamer.h" |
| #include "llvm/MC/MCSection.h" |
| #include "llvm/MC/MCSectionMachO.h" |
| #include "llvm/MC/MCSymbol.h" |
| #include "llvm/Support/Dwarf.h" |
| #include "llvm/Support/ErrorHandling.h" |
| #include "llvm/Support/raw_ostream.h" |
| |
| using namespace llvm; |
| |
| namespace { |
| |
| class MCMachOStreamer : public MCObjectStreamer { |
| private: |
| /// LabelSections - true if each section change should emit a linker local |
| /// label for use in relocations for assembler local references. Obviates the |
| /// need for local relocations. False by default. |
| bool LabelSections; |
| |
| /// HasSectionLabel - map of which sections have already had a non-local |
| /// label emitted to them. Used so we don't emit extraneous linker local |
| /// labels in the middle of the section. |
| DenseMap<const MCSection*, bool> HasSectionLabel; |
| |
| void EmitInstToData(const MCInst &Inst, const MCSubtargetInfo &STI) override; |
| |
| void EmitDataRegion(DataRegionData::KindTy Kind); |
| void EmitDataRegionEnd(); |
| |
| public: |
| MCMachOStreamer(MCContext &Context, MCAsmBackend &MAB, raw_ostream &OS, |
| MCCodeEmitter *Emitter, bool label) |
| : MCObjectStreamer(Context, MAB, OS, Emitter), |
| LabelSections(label) {} |
| |
| /// state management |
| void reset() override { |
| HasSectionLabel.clear(); |
| MCObjectStreamer::reset(); |
| } |
| |
| /// @name MCStreamer Interface |
| /// @{ |
| |
| void ChangeSection(const MCSection *Sect, const MCExpr *Subsect) override; |
| void EmitLabel(MCSymbol *Symbol) override; |
| void EmitEHSymAttributes(const MCSymbol *Symbol, MCSymbol *EHSymbol) override; |
| void EmitAssemblerFlag(MCAssemblerFlag Flag) override; |
| void EmitLinkerOptions(ArrayRef<std::string> Options) override; |
| void EmitDataRegion(MCDataRegionType Kind) override; |
| void EmitVersionMin(MCVersionMinType Kind, unsigned Major, |
| unsigned Minor, unsigned Update) override; |
| void EmitThumbFunc(MCSymbol *Func) override; |
| bool EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) override; |
| void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) override; |
| void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size, |
| unsigned ByteAlignment) override; |
| void BeginCOFFSymbolDef(const MCSymbol *Symbol) override { |
| llvm_unreachable("macho doesn't support this directive"); |
| } |
| void EmitCOFFSymbolStorageClass(int StorageClass) override { |
| llvm_unreachable("macho doesn't support this directive"); |
| } |
| void EmitCOFFSymbolType(int Type) override { |
| llvm_unreachable("macho doesn't support this directive"); |
| } |
| void EndCOFFSymbolDef() override { |
| llvm_unreachable("macho doesn't support this directive"); |
| } |
| void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) override { |
| llvm_unreachable("macho doesn't support this directive"); |
| } |
| void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size, |
| unsigned ByteAlignment) override; |
| void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = nullptr, |
| uint64_t Size = 0, unsigned ByteAlignment = 0) override; |
| void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol, uint64_t Size, |
| unsigned ByteAlignment = 0) override; |
| |
| void EmitFileDirective(StringRef Filename) override { |
| // FIXME: Just ignore the .file; it isn't important enough to fail the |
| // entire assembly. |
| |
| // report_fatal_error("unsupported directive: '.file'"); |
| } |
| |
| void EmitIdent(StringRef IdentString) override { |
| llvm_unreachable("macho doesn't support this directive"); |
| } |
| |
| void EmitLOHDirective(MCLOHType Kind, const MCLOHArgs &Args) override { |
| getAssembler().getLOHContainer().addDirective(Kind, Args); |
| } |
| |
| void FinishImpl() override; |
| }; |
| |
| } // end anonymous namespace. |
| |
| void MCMachOStreamer::ChangeSection(const MCSection *Section, |
| const MCExpr *Subsection) { |
| // Change the section normally. |
| MCObjectStreamer::ChangeSection(Section, Subsection); |
| // Output a linker-local symbol so we don't need section-relative local |
| // relocations. The linker hates us when we do that. |
| if (LabelSections && !HasSectionLabel[Section]) { |
| MCSymbol *Label = getContext().CreateLinkerPrivateTempSymbol(); |
| EmitLabel(Label); |
| HasSectionLabel[Section] = true; |
| } |
| } |
| |
| void MCMachOStreamer::EmitEHSymAttributes(const MCSymbol *Symbol, |
| MCSymbol *EHSymbol) { |
| MCSymbolData &SD = |
| getAssembler().getOrCreateSymbolData(*Symbol); |
| if (SD.isExternal()) |
| EmitSymbolAttribute(EHSymbol, MCSA_Global); |
| if (SD.getFlags() & SF_WeakDefinition) |
| EmitSymbolAttribute(EHSymbol, MCSA_WeakDefinition); |
| if (SD.isPrivateExtern()) |
| EmitSymbolAttribute(EHSymbol, MCSA_PrivateExtern); |
| } |
| |
| void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) { |
| assert(Symbol->isUndefined() && "Cannot define a symbol twice!"); |
| |
| // isSymbolLinkerVisible uses the section. |
| AssignSection(Symbol, getCurrentSection().first); |
| // We have to create a new fragment if this is an atom defining symbol, |
| // fragments cannot span atoms. |
| if (getAssembler().isSymbolLinkerVisible(*Symbol)) |
| insert(new MCDataFragment()); |
| |
| MCObjectStreamer::EmitLabel(Symbol); |
| |
| MCSymbolData &SD = getAssembler().getSymbolData(*Symbol); |
| // This causes the reference type flag to be cleared. Darwin 'as' was "trying" |
| // to clear the weak reference and weak definition bits too, but the |
| // implementation was buggy. For now we just try to match 'as', for |
| // diffability. |
| // |
| // FIXME: Cleanup this code, these bits should be emitted based on semantic |
| // properties, not on the order of definition, etc. |
| SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask); |
| } |
| |
| void MCMachOStreamer::EmitDataRegion(DataRegionData::KindTy Kind) { |
| if (!getAssembler().getBackend().hasDataInCodeSupport()) |
| return; |
| // Create a temporary label to mark the start of the data region. |
| MCSymbol *Start = getContext().CreateTempSymbol(); |
| EmitLabel(Start); |
| // Record the region for the object writer to use. |
| DataRegionData Data = { Kind, Start, nullptr }; |
| std::vector<DataRegionData> &Regions = getAssembler().getDataRegions(); |
| Regions.push_back(Data); |
| } |
| |
| void MCMachOStreamer::EmitDataRegionEnd() { |
| if (!getAssembler().getBackend().hasDataInCodeSupport()) |
| return; |
| std::vector<DataRegionData> &Regions = getAssembler().getDataRegions(); |
| assert(Regions.size() && "Mismatched .end_data_region!"); |
| DataRegionData &Data = Regions.back(); |
| assert(!Data.End && "Mismatched .end_data_region!"); |
| // Create a temporary label to mark the end of the data region. |
| Data.End = getContext().CreateTempSymbol(); |
| EmitLabel(Data.End); |
| } |
| |
| void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) { |
| // Let the target do whatever target specific stuff it needs to do. |
| getAssembler().getBackend().handleAssemblerFlag(Flag); |
| // Do any generic stuff we need to do. |
| switch (Flag) { |
| case MCAF_SyntaxUnified: return; // no-op here. |
| case MCAF_Code16: return; // Change parsing mode; no-op here. |
| case MCAF_Code32: return; // Change parsing mode; no-op here. |
| case MCAF_Code64: return; // Change parsing mode; no-op here. |
| case MCAF_SubsectionsViaSymbols: |
| getAssembler().setSubsectionsViaSymbols(true); |
| return; |
| } |
| } |
| |
| void MCMachOStreamer::EmitLinkerOptions(ArrayRef<std::string> Options) { |
| getAssembler().getLinkerOptions().push_back(Options); |
| } |
| |
| void MCMachOStreamer::EmitDataRegion(MCDataRegionType Kind) { |
| switch (Kind) { |
| case MCDR_DataRegion: |
| EmitDataRegion(DataRegionData::Data); |
| return; |
| case MCDR_DataRegionJT8: |
| EmitDataRegion(DataRegionData::JumpTable8); |
| return; |
| case MCDR_DataRegionJT16: |
| EmitDataRegion(DataRegionData::JumpTable16); |
| return; |
| case MCDR_DataRegionJT32: |
| EmitDataRegion(DataRegionData::JumpTable32); |
| return; |
| case MCDR_DataRegionEnd: |
| EmitDataRegionEnd(); |
| return; |
| } |
| } |
| |
| void MCMachOStreamer::EmitVersionMin(MCVersionMinType Kind, unsigned Major, |
| unsigned Minor, unsigned Update) { |
| getAssembler().setVersionMinInfo(Kind, Major, Minor, Update); |
| } |
| |
| void MCMachOStreamer::EmitThumbFunc(MCSymbol *Symbol) { |
| // Remember that the function is a thumb function. Fixup and relocation |
| // values will need adjusted. |
| getAssembler().setIsThumbFunc(Symbol); |
| } |
| |
| bool MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol, |
| MCSymbolAttr Attribute) { |
| // Indirect symbols are handled differently, to match how 'as' handles |
| // them. This makes writing matching .o files easier. |
| if (Attribute == MCSA_IndirectSymbol) { |
| // Note that we intentionally cannot use the symbol data here; this is |
| // important for matching the string table that 'as' generates. |
| IndirectSymbolData ISD; |
| ISD.Symbol = Symbol; |
| ISD.SectionData = getCurrentSectionData(); |
| getAssembler().getIndirectSymbols().push_back(ISD); |
| return true; |
| } |
| |
| // Adding a symbol attribute always introduces the symbol, note that an |
| // important side effect of calling getOrCreateSymbolData here is to register |
| // the symbol with the assembler. |
| MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol); |
| |
| // The implementation of symbol attributes is designed to match 'as', but it |
| // leaves much to desired. It doesn't really make sense to arbitrarily add and |
| // remove flags, but 'as' allows this (in particular, see .desc). |
| // |
| // In the future it might be worth trying to make these operations more well |
| // defined. |
| switch (Attribute) { |
| case MCSA_Invalid: |
| case MCSA_ELF_TypeFunction: |
| case MCSA_ELF_TypeIndFunction: |
| case MCSA_ELF_TypeObject: |
| case MCSA_ELF_TypeTLS: |
| case MCSA_ELF_TypeCommon: |
| case MCSA_ELF_TypeNoType: |
| case MCSA_ELF_TypeGnuUniqueObject: |
| case MCSA_Hidden: |
| case MCSA_IndirectSymbol: |
| case MCSA_Internal: |
| case MCSA_Protected: |
| case MCSA_Weak: |
| case MCSA_Local: |
| return false; |
| |
| case MCSA_Global: |
| SD.setExternal(true); |
| // This effectively clears the undefined lazy bit, in Darwin 'as', although |
| // it isn't very consistent because it implements this as part of symbol |
| // lookup. |
| // |
| // FIXME: Cleanup this code, these bits should be emitted based on semantic |
| // properties, not on the order of definition, etc. |
| SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy); |
| break; |
| |
| case MCSA_LazyReference: |
| // FIXME: This requires -dynamic. |
| SD.setFlags(SD.getFlags() | SF_NoDeadStrip); |
| if (Symbol->isUndefined()) |
| SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy); |
| break; |
| |
| // Since .reference sets the no dead strip bit, it is equivalent to |
| // .no_dead_strip in practice. |
| case MCSA_Reference: |
| case MCSA_NoDeadStrip: |
| SD.setFlags(SD.getFlags() | SF_NoDeadStrip); |
| break; |
| |
| case MCSA_SymbolResolver: |
| SD.setFlags(SD.getFlags() | SF_SymbolResolver); |
| break; |
| |
| case MCSA_PrivateExtern: |
| SD.setExternal(true); |
| SD.setPrivateExtern(true); |
| break; |
| |
| case MCSA_WeakReference: |
| // FIXME: This requires -dynamic. |
| if (Symbol->isUndefined()) |
| SD.setFlags(SD.getFlags() | SF_WeakReference); |
| break; |
| |
| case MCSA_WeakDefinition: |
| // FIXME: 'as' enforces that this is defined and global. The manual claims |
| // it has to be in a coalesced section, but this isn't enforced. |
| SD.setFlags(SD.getFlags() | SF_WeakDefinition); |
| break; |
| |
| case MCSA_WeakDefAutoPrivate: |
| SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference); |
| break; |
| } |
| |
| return true; |
| } |
| |
| void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) { |
| // Encode the 'desc' value into the lowest implementation defined bits. |
| assert(DescValue == (DescValue & SF_DescFlagsMask) && |
| "Invalid .desc value!"); |
| getAssembler().getOrCreateSymbolData(*Symbol).setFlags( |
| DescValue & SF_DescFlagsMask); |
| } |
| |
| void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size, |
| unsigned ByteAlignment) { |
| // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself. |
| assert(Symbol->isUndefined() && "Cannot define a symbol twice!"); |
| |
| AssignSection(Symbol, nullptr); |
| |
| MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol); |
| SD.setExternal(true); |
| SD.setCommon(Size, ByteAlignment); |
| } |
| |
| void MCMachOStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size, |
| unsigned ByteAlignment) { |
| // '.lcomm' is equivalent to '.zerofill'. |
| return EmitZerofill(getContext().getObjectFileInfo()->getDataBSSSection(), |
| Symbol, Size, ByteAlignment); |
| } |
| |
| void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol, |
| uint64_t Size, unsigned ByteAlignment) { |
| MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section); |
| |
| // The symbol may not be present, which only creates the section. |
| if (!Symbol) |
| return; |
| |
| // On darwin all virtual sections have zerofill type. |
| assert(Section->isVirtualSection() && "Section does not have zerofill type!"); |
| |
| assert(Symbol->isUndefined() && "Cannot define a symbol twice!"); |
| |
| MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol); |
| |
| // Emit an align fragment if necessary. |
| if (ByteAlignment != 1) |
| new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData); |
| |
| MCFragment *F = new MCFillFragment(0, 0, Size, &SectData); |
| SD.setFragment(F); |
| |
| AssignSection(Symbol, Section); |
| |
| // Update the maximum alignment on the zero fill section if necessary. |
| if (ByteAlignment > SectData.getAlignment()) |
| SectData.setAlignment(ByteAlignment); |
| } |
| |
| // This should always be called with the thread local bss section. Like the |
| // .zerofill directive this doesn't actually switch sections on us. |
| void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol, |
| uint64_t Size, unsigned ByteAlignment) { |
| EmitZerofill(Section, Symbol, Size, ByteAlignment); |
| return; |
| } |
| |
| void MCMachOStreamer::EmitInstToData(const MCInst &Inst, |
| const MCSubtargetInfo &STI) { |
| MCDataFragment *DF = getOrCreateDataFragment(); |
| |
| SmallVector<MCFixup, 4> Fixups; |
| SmallString<256> Code; |
| raw_svector_ostream VecOS(Code); |
| getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups, STI); |
| VecOS.flush(); |
| |
| // Add the fixups and data. |
| for (unsigned i = 0, e = Fixups.size(); i != e; ++i) { |
| Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size()); |
| DF->getFixups().push_back(Fixups[i]); |
| } |
| DF->getContents().append(Code.begin(), Code.end()); |
| } |
| |
| void MCMachOStreamer::FinishImpl() { |
| EmitFrames(&getAssembler().getBackend()); |
| |
| // We have to set the fragment atom associations so we can relax properly for |
| // Mach-O. |
| |
| // First, scan the symbol table to build a lookup table from fragments to |
| // defining symbols. |
| DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap; |
| for (MCSymbolData &SD : getAssembler().symbols()) { |
| if (getAssembler().isSymbolLinkerVisible(SD.getSymbol()) && |
| SD.getFragment()) { |
| // An atom defining symbol should never be internal to a fragment. |
| assert(SD.getOffset() == 0 && "Invalid offset in atom defining symbol!"); |
| DefiningSymbolMap[SD.getFragment()] = &SD; |
| } |
| } |
| |
| // Set the fragment atom associations by tracking the last seen atom defining |
| // symbol. |
| for (MCAssembler::iterator it = getAssembler().begin(), |
| ie = getAssembler().end(); it != ie; ++it) { |
| MCSymbolData *CurrentAtom = nullptr; |
| for (MCSectionData::iterator it2 = it->begin(), |
| ie2 = it->end(); it2 != ie2; ++it2) { |
| if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2)) |
| CurrentAtom = SD; |
| it2->setAtom(CurrentAtom); |
| } |
| } |
| |
| this->MCObjectStreamer::FinishImpl(); |
| } |
| |
| MCStreamer *llvm::createMachOStreamer(MCContext &Context, MCAsmBackend &MAB, |
| raw_ostream &OS, MCCodeEmitter *CE, |
| bool RelaxAll, |
| bool LabelSections) { |
| MCMachOStreamer *S = new MCMachOStreamer(Context, MAB, OS, CE, LabelSections); |
| if (RelaxAll) |
| S->getAssembler().setRelaxAll(true); |
| return S; |
| } |