| //===-- llvm/MC/WinCOFFObjectWriter.cpp -------------------------*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file contains an implementation of a Win32 COFF object file writer. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/MC/MCWinCOFFObjectWriter.h" |
| #include "llvm/ADT/DenseMap.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include "llvm/ADT/StringMap.h" |
| #include "llvm/ADT/StringRef.h" |
| #include "llvm/ADT/Twine.h" |
| #include "llvm/MC/MCAsmLayout.h" |
| #include "llvm/MC/MCAssembler.h" |
| #include "llvm/MC/MCContext.h" |
| #include "llvm/MC/MCExpr.h" |
| #include "llvm/MC/MCObjectFileInfo.h" |
| #include "llvm/MC/MCObjectWriter.h" |
| #include "llvm/MC/MCSection.h" |
| #include "llvm/MC/MCSectionCOFF.h" |
| #include "llvm/MC/MCSymbolCOFF.h" |
| #include "llvm/MC/MCValue.h" |
| #include "llvm/MC/StringTableBuilder.h" |
| #include "llvm/Support/COFF.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/Endian.h" |
| #include "llvm/Support/ErrorHandling.h" |
| #include "llvm/Support/TimeValue.h" |
| #include <cstdio> |
| |
| using namespace llvm; |
| |
| #define DEBUG_TYPE "WinCOFFObjectWriter" |
| |
| namespace { |
| typedef SmallString<COFF::NameSize> name; |
| |
| enum AuxiliaryType { |
| ATFunctionDefinition, |
| ATbfAndefSymbol, |
| ATWeakExternal, |
| ATFile, |
| ATSectionDefinition |
| }; |
| |
| struct AuxSymbol { |
| AuxiliaryType AuxType; |
| COFF::Auxiliary Aux; |
| }; |
| |
| class COFFSymbol; |
| class COFFSection; |
| |
| class COFFSymbol { |
| public: |
| COFF::symbol Data; |
| |
| typedef SmallVector<AuxSymbol, 1> AuxiliarySymbols; |
| |
| name Name; |
| int Index; |
| AuxiliarySymbols Aux; |
| COFFSymbol *Other; |
| COFFSection *Section; |
| int Relocations; |
| |
| const MCSymbol *MC; |
| |
| COFFSymbol(StringRef name); |
| void set_name_offset(uint32_t Offset); |
| |
| bool should_keep() const; |
| |
| int64_t getIndex() const { return Index; } |
| void setIndex(int Value) { |
| Index = Value; |
| if (MC) |
| MC->setIndex(static_cast<uint32_t>(Value)); |
| } |
| }; |
| |
| // This class contains staging data for a COFF relocation entry. |
| struct COFFRelocation { |
| COFF::relocation Data; |
| COFFSymbol *Symb; |
| |
| COFFRelocation() : Symb(nullptr) {} |
| static size_t size() { return COFF::RelocationSize; } |
| }; |
| |
| typedef std::vector<COFFRelocation> relocations; |
| |
| class COFFSection { |
| public: |
| COFF::section Header; |
| |
| std::string Name; |
| int Number; |
| MCSectionCOFF const *MCSection; |
| COFFSymbol *Symbol; |
| relocations Relocations; |
| |
| COFFSection(StringRef name); |
| static size_t size(); |
| }; |
| |
| class WinCOFFObjectWriter : public MCObjectWriter { |
| public: |
| typedef std::vector<std::unique_ptr<COFFSymbol>> symbols; |
| typedef std::vector<std::unique_ptr<COFFSection>> sections; |
| |
| typedef DenseMap<MCSymbol const *, COFFSymbol *> symbol_map; |
| typedef DenseMap<MCSection const *, COFFSection *> section_map; |
| |
| std::unique_ptr<MCWinCOFFObjectTargetWriter> TargetObjectWriter; |
| |
| // Root level file contents. |
| COFF::header Header; |
| sections Sections; |
| symbols Symbols; |
| StringTableBuilder Strings; |
| |
| // Maps used during object file creation. |
| section_map SectionMap; |
| symbol_map SymbolMap; |
| |
| bool UseBigObj; |
| |
| WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW, raw_pwrite_stream &OS); |
| |
| void reset() override { |
| memset(&Header, 0, sizeof(Header)); |
| Header.Machine = TargetObjectWriter->getMachine(); |
| Sections.clear(); |
| Symbols.clear(); |
| Strings.clear(); |
| SectionMap.clear(); |
| SymbolMap.clear(); |
| MCObjectWriter::reset(); |
| } |
| |
| COFFSymbol *createSymbol(StringRef Name); |
| COFFSymbol *GetOrCreateCOFFSymbol(const MCSymbol *Symbol); |
| COFFSection *createSection(StringRef Name); |
| |
| template <typename object_t, typename list_t> |
| object_t *createCOFFEntity(StringRef Name, list_t &List); |
| |
| void defineSection(MCSectionCOFF const &Sec); |
| void DefineSymbol(const MCSymbol &Symbol, MCAssembler &Assembler, |
| const MCAsmLayout &Layout); |
| |
| void SetSymbolName(COFFSymbol &S); |
| void SetSectionName(COFFSection &S); |
| |
| bool ExportSymbol(const MCSymbol &Symbol, MCAssembler &Asm); |
| |
| bool IsPhysicalSection(COFFSection *S); |
| |
| // Entity writing methods. |
| |
| void WriteFileHeader(const COFF::header &Header); |
| void WriteSymbol(const COFFSymbol &S); |
| void WriteAuxiliarySymbols(const COFFSymbol::AuxiliarySymbols &S); |
| void writeSectionHeader(const COFF::section &S); |
| void WriteRelocation(const COFF::relocation &R); |
| |
| // MCObjectWriter interface implementation. |
| |
| void executePostLayoutBinding(MCAssembler &Asm, |
| const MCAsmLayout &Layout) override; |
| |
| bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm, |
| const MCSymbol &SymA, |
| const MCFragment &FB, bool InSet, |
| bool IsPCRel) const override; |
| |
| bool isWeak(const MCSymbol &Sym) const override; |
| |
| void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout, |
| const MCFragment *Fragment, const MCFixup &Fixup, |
| MCValue Target, bool &IsPCRel, |
| uint64_t &FixedValue) override; |
| |
| void writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override; |
| }; |
| } |
| |
| static inline void write_uint32_le(void *Data, uint32_t Value) { |
| support::endian::write<uint32_t, support::little, support::unaligned>(Data, |
| Value); |
| } |
| |
| //------------------------------------------------------------------------------ |
| // Symbol class implementation |
| |
| COFFSymbol::COFFSymbol(StringRef name) |
| : Name(name.begin(), name.end()), Other(nullptr), Section(nullptr), |
| Relocations(0), MC(nullptr) { |
| memset(&Data, 0, sizeof(Data)); |
| } |
| |
| // In the case that the name does not fit within 8 bytes, the offset |
| // into the string table is stored in the last 4 bytes instead, leaving |
| // the first 4 bytes as 0. |
| void COFFSymbol::set_name_offset(uint32_t Offset) { |
| write_uint32_le(Data.Name + 0, 0); |
| write_uint32_le(Data.Name + 4, Offset); |
| } |
| |
| /// logic to decide if the symbol should be reported in the symbol table |
| bool COFFSymbol::should_keep() const { |
| // no section means its external, keep it |
| if (!Section) |
| return true; |
| |
| // if it has relocations pointing at it, keep it |
| if (Relocations > 0) { |
| assert(Section->Number != -1 && "Sections with relocations must be real!"); |
| return true; |
| } |
| |
| // if this is a safeseh handler, keep it |
| if (MC && (cast<MCSymbolCOFF>(MC)->isSafeSEH())) |
| return true; |
| |
| // if the section its in is being droped, drop it |
| if (Section->Number == -1) |
| return false; |
| |
| // if it is the section symbol, keep it |
| if (Section->Symbol == this) |
| return true; |
| |
| // if its temporary, drop it |
| if (MC && MC->isTemporary()) |
| return false; |
| |
| // otherwise, keep it |
| return true; |
| } |
| |
| //------------------------------------------------------------------------------ |
| // Section class implementation |
| |
| COFFSection::COFFSection(StringRef name) |
| : Name(name), MCSection(nullptr), Symbol(nullptr) { |
| memset(&Header, 0, sizeof(Header)); |
| } |
| |
| size_t COFFSection::size() { return COFF::SectionSize; } |
| |
| //------------------------------------------------------------------------------ |
| // WinCOFFObjectWriter class implementation |
| |
| WinCOFFObjectWriter::WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW, |
| raw_pwrite_stream &OS) |
| : MCObjectWriter(OS, true), TargetObjectWriter(MOTW) { |
| memset(&Header, 0, sizeof(Header)); |
| |
| Header.Machine = TargetObjectWriter->getMachine(); |
| } |
| |
| COFFSymbol *WinCOFFObjectWriter::createSymbol(StringRef Name) { |
| return createCOFFEntity<COFFSymbol>(Name, Symbols); |
| } |
| |
| COFFSymbol *WinCOFFObjectWriter::GetOrCreateCOFFSymbol(const MCSymbol *Symbol) { |
| symbol_map::iterator i = SymbolMap.find(Symbol); |
| if (i != SymbolMap.end()) |
| return i->second; |
| COFFSymbol *RetSymbol = |
| createCOFFEntity<COFFSymbol>(Symbol->getName(), Symbols); |
| SymbolMap[Symbol] = RetSymbol; |
| return RetSymbol; |
| } |
| |
| COFFSection *WinCOFFObjectWriter::createSection(StringRef Name) { |
| return createCOFFEntity<COFFSection>(Name, Sections); |
| } |
| |
| /// A template used to lookup or create a symbol/section, and initialize it if |
| /// needed. |
| template <typename object_t, typename list_t> |
| object_t *WinCOFFObjectWriter::createCOFFEntity(StringRef Name, list_t &List) { |
| List.push_back(make_unique<object_t>(Name)); |
| |
| return List.back().get(); |
| } |
| |
| /// This function takes a section data object from the assembler |
| /// and creates the associated COFF section staging object. |
| void WinCOFFObjectWriter::defineSection(MCSectionCOFF const &Sec) { |
| COFFSection *coff_section = createSection(Sec.getSectionName()); |
| COFFSymbol *coff_symbol = createSymbol(Sec.getSectionName()); |
| if (Sec.getSelection() != COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) { |
| if (const MCSymbol *S = Sec.getCOMDATSymbol()) { |
| COFFSymbol *COMDATSymbol = GetOrCreateCOFFSymbol(S); |
| if (COMDATSymbol->Section) |
| report_fatal_error("two sections have the same comdat"); |
| COMDATSymbol->Section = coff_section; |
| } |
| } |
| |
| coff_section->Symbol = coff_symbol; |
| coff_symbol->Section = coff_section; |
| coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_STATIC; |
| |
| // In this case the auxiliary symbol is a Section Definition. |
| coff_symbol->Aux.resize(1); |
| memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0])); |
| coff_symbol->Aux[0].AuxType = ATSectionDefinition; |
| coff_symbol->Aux[0].Aux.SectionDefinition.Selection = Sec.getSelection(); |
| |
| coff_section->Header.Characteristics = Sec.getCharacteristics(); |
| |
| uint32_t &Characteristics = coff_section->Header.Characteristics; |
| switch (Sec.getAlignment()) { |
| case 1: |
| Characteristics |= COFF::IMAGE_SCN_ALIGN_1BYTES; |
| break; |
| case 2: |
| Characteristics |= COFF::IMAGE_SCN_ALIGN_2BYTES; |
| break; |
| case 4: |
| Characteristics |= COFF::IMAGE_SCN_ALIGN_4BYTES; |
| break; |
| case 8: |
| Characteristics |= COFF::IMAGE_SCN_ALIGN_8BYTES; |
| break; |
| case 16: |
| Characteristics |= COFF::IMAGE_SCN_ALIGN_16BYTES; |
| break; |
| case 32: |
| Characteristics |= COFF::IMAGE_SCN_ALIGN_32BYTES; |
| break; |
| case 64: |
| Characteristics |= COFF::IMAGE_SCN_ALIGN_64BYTES; |
| break; |
| case 128: |
| Characteristics |= COFF::IMAGE_SCN_ALIGN_128BYTES; |
| break; |
| case 256: |
| Characteristics |= COFF::IMAGE_SCN_ALIGN_256BYTES; |
| break; |
| case 512: |
| Characteristics |= COFF::IMAGE_SCN_ALIGN_512BYTES; |
| break; |
| case 1024: |
| Characteristics |= COFF::IMAGE_SCN_ALIGN_1024BYTES; |
| break; |
| case 2048: |
| Characteristics |= COFF::IMAGE_SCN_ALIGN_2048BYTES; |
| break; |
| case 4096: |
| Characteristics |= COFF::IMAGE_SCN_ALIGN_4096BYTES; |
| break; |
| case 8192: |
| Characteristics |= COFF::IMAGE_SCN_ALIGN_8192BYTES; |
| break; |
| default: |
| llvm_unreachable("unsupported section alignment"); |
| } |
| |
| // Bind internal COFF section to MC section. |
| coff_section->MCSection = &Sec; |
| SectionMap[&Sec] = coff_section; |
| } |
| |
| static uint64_t getSymbolValue(const MCSymbol &Symbol, |
| const MCAsmLayout &Layout) { |
| if (Symbol.isCommon() && Symbol.isExternal()) |
| return Symbol.getCommonSize(); |
| |
| uint64_t Res; |
| if (!Layout.getSymbolOffset(Symbol, Res)) |
| return 0; |
| |
| return Res; |
| } |
| |
| /// This function takes a symbol data object from the assembler |
| /// and creates the associated COFF symbol staging object. |
| void WinCOFFObjectWriter::DefineSymbol(const MCSymbol &Symbol, |
| MCAssembler &Assembler, |
| const MCAsmLayout &Layout) { |
| COFFSymbol *coff_symbol = GetOrCreateCOFFSymbol(&Symbol); |
| SymbolMap[&Symbol] = coff_symbol; |
| |
| if (cast<MCSymbolCOFF>(Symbol).isWeakExternal()) { |
| coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL; |
| |
| if (Symbol.isVariable()) { |
| const MCSymbolRefExpr *SymRef = |
| dyn_cast<MCSymbolRefExpr>(Symbol.getVariableValue()); |
| |
| if (!SymRef) |
| report_fatal_error("Weak externals may only alias symbols"); |
| |
| coff_symbol->Other = GetOrCreateCOFFSymbol(&SymRef->getSymbol()); |
| } else { |
| std::string WeakName = (".weak." + Symbol.getName() + ".default").str(); |
| COFFSymbol *WeakDefault = createSymbol(WeakName); |
| WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE; |
| WeakDefault->Data.StorageClass = COFF::IMAGE_SYM_CLASS_EXTERNAL; |
| WeakDefault->Data.Type = 0; |
| WeakDefault->Data.Value = 0; |
| coff_symbol->Other = WeakDefault; |
| } |
| |
| // Setup the Weak External auxiliary symbol. |
| coff_symbol->Aux.resize(1); |
| memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0])); |
| coff_symbol->Aux[0].AuxType = ATWeakExternal; |
| coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = 0; |
| coff_symbol->Aux[0].Aux.WeakExternal.Characteristics = |
| COFF::IMAGE_WEAK_EXTERN_SEARCH_LIBRARY; |
| |
| coff_symbol->MC = &Symbol; |
| } else { |
| const MCSymbol *Base = Layout.getBaseSymbol(Symbol); |
| coff_symbol->Data.Value = getSymbolValue(Symbol, Layout); |
| |
| const MCSymbolCOFF &SymbolCOFF = cast<MCSymbolCOFF>(Symbol); |
| coff_symbol->Data.Type = SymbolCOFF.getType(); |
| coff_symbol->Data.StorageClass = SymbolCOFF.getClass(); |
| |
| // If no storage class was specified in the streamer, define it here. |
| if (coff_symbol->Data.StorageClass == COFF::IMAGE_SYM_CLASS_NULL) { |
| bool IsExternal = Symbol.isExternal() || |
| (!Symbol.getFragment() && !Symbol.isVariable()); |
| |
| coff_symbol->Data.StorageClass = IsExternal |
| ? COFF::IMAGE_SYM_CLASS_EXTERNAL |
| : COFF::IMAGE_SYM_CLASS_STATIC; |
| } |
| |
| if (!Base) { |
| coff_symbol->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE; |
| } else { |
| if (Base->getFragment()) { |
| COFFSection *Sec = SectionMap[Base->getFragment()->getParent()]; |
| |
| if (coff_symbol->Section && coff_symbol->Section != Sec) |
| report_fatal_error("conflicting sections for symbol"); |
| |
| coff_symbol->Section = Sec; |
| } |
| } |
| |
| coff_symbol->MC = &Symbol; |
| } |
| } |
| |
| // Maximum offsets for different string table entry encodings. |
| static const unsigned Max6DecimalOffset = 999999; |
| static const unsigned Max7DecimalOffset = 9999999; |
| static const uint64_t MaxBase64Offset = 0xFFFFFFFFFULL; // 64^6, including 0 |
| |
| // Encode a string table entry offset in base 64, padded to 6 chars, and |
| // prefixed with a double slash: '//AAAAAA', '//AAAAAB', ... |
| // Buffer must be at least 8 bytes large. No terminating null appended. |
| static void encodeBase64StringEntry(char *Buffer, uint64_t Value) { |
| assert(Value > Max7DecimalOffset && Value <= MaxBase64Offset && |
| "Illegal section name encoding for value"); |
| |
| static const char Alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" |
| "abcdefghijklmnopqrstuvwxyz" |
| "0123456789+/"; |
| |
| Buffer[0] = '/'; |
| Buffer[1] = '/'; |
| |
| char *Ptr = Buffer + 7; |
| for (unsigned i = 0; i < 6; ++i) { |
| unsigned Rem = Value % 64; |
| Value /= 64; |
| *(Ptr--) = Alphabet[Rem]; |
| } |
| } |
| |
| void WinCOFFObjectWriter::SetSectionName(COFFSection &S) { |
| if (S.Name.size() > COFF::NameSize) { |
| uint64_t StringTableEntry = Strings.getOffset(S.Name); |
| |
| if (StringTableEntry <= Max6DecimalOffset) { |
| std::sprintf(S.Header.Name, "/%d", unsigned(StringTableEntry)); |
| } else if (StringTableEntry <= Max7DecimalOffset) { |
| // With seven digits, we have to skip the terminating null. Because |
| // sprintf always appends it, we use a larger temporary buffer. |
| char buffer[9] = {}; |
| std::sprintf(buffer, "/%d", unsigned(StringTableEntry)); |
| std::memcpy(S.Header.Name, buffer, 8); |
| } else if (StringTableEntry <= MaxBase64Offset) { |
| // Starting with 10,000,000, offsets are encoded as base64. |
| encodeBase64StringEntry(S.Header.Name, StringTableEntry); |
| } else { |
| report_fatal_error("COFF string table is greater than 64 GB."); |
| } |
| } else |
| std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size()); |
| } |
| |
| void WinCOFFObjectWriter::SetSymbolName(COFFSymbol &S) { |
| if (S.Name.size() > COFF::NameSize) |
| S.set_name_offset(Strings.getOffset(S.Name)); |
| else |
| std::memcpy(S.Data.Name, S.Name.c_str(), S.Name.size()); |
| } |
| |
| bool WinCOFFObjectWriter::ExportSymbol(const MCSymbol &Symbol, |
| MCAssembler &Asm) { |
| // This doesn't seem to be right. Strings referred to from the .data section |
| // need symbols so they can be linked to code in the .text section right? |
| |
| // return Asm.isSymbolLinkerVisible(Symbol); |
| |
| // Non-temporary labels should always be visible to the linker. |
| if (!Symbol.isTemporary()) |
| return true; |
| |
| // Temporary variable symbols are invisible. |
| if (Symbol.isVariable()) |
| return false; |
| |
| // Absolute temporary labels are never visible. |
| return !Symbol.isAbsolute(); |
| } |
| |
| bool WinCOFFObjectWriter::IsPhysicalSection(COFFSection *S) { |
| return (S->Header.Characteristics & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) == |
| 0; |
| } |
| |
| //------------------------------------------------------------------------------ |
| // entity writing methods |
| |
| void WinCOFFObjectWriter::WriteFileHeader(const COFF::header &Header) { |
| if (UseBigObj) { |
| writeLE16(COFF::IMAGE_FILE_MACHINE_UNKNOWN); |
| writeLE16(0xFFFF); |
| writeLE16(COFF::BigObjHeader::MinBigObjectVersion); |
| writeLE16(Header.Machine); |
| writeLE32(Header.TimeDateStamp); |
| writeBytes(StringRef(COFF::BigObjMagic, sizeof(COFF::BigObjMagic))); |
| writeLE32(0); |
| writeLE32(0); |
| writeLE32(0); |
| writeLE32(0); |
| writeLE32(Header.NumberOfSections); |
| writeLE32(Header.PointerToSymbolTable); |
| writeLE32(Header.NumberOfSymbols); |
| } else { |
| writeLE16(Header.Machine); |
| writeLE16(static_cast<int16_t>(Header.NumberOfSections)); |
| writeLE32(Header.TimeDateStamp); |
| writeLE32(Header.PointerToSymbolTable); |
| writeLE32(Header.NumberOfSymbols); |
| writeLE16(Header.SizeOfOptionalHeader); |
| writeLE16(Header.Characteristics); |
| } |
| } |
| |
| void WinCOFFObjectWriter::WriteSymbol(const COFFSymbol &S) { |
| writeBytes(StringRef(S.Data.Name, COFF::NameSize)); |
| writeLE32(S.Data.Value); |
| if (UseBigObj) |
| writeLE32(S.Data.SectionNumber); |
| else |
| writeLE16(static_cast<int16_t>(S.Data.SectionNumber)); |
| writeLE16(S.Data.Type); |
| write8(S.Data.StorageClass); |
| write8(S.Data.NumberOfAuxSymbols); |
| WriteAuxiliarySymbols(S.Aux); |
| } |
| |
| void WinCOFFObjectWriter::WriteAuxiliarySymbols( |
| const COFFSymbol::AuxiliarySymbols &S) { |
| for (COFFSymbol::AuxiliarySymbols::const_iterator i = S.begin(), e = S.end(); |
| i != e; ++i) { |
| switch (i->AuxType) { |
| case ATFunctionDefinition: |
| writeLE32(i->Aux.FunctionDefinition.TagIndex); |
| writeLE32(i->Aux.FunctionDefinition.TotalSize); |
| writeLE32(i->Aux.FunctionDefinition.PointerToLinenumber); |
| writeLE32(i->Aux.FunctionDefinition.PointerToNextFunction); |
| WriteZeros(sizeof(i->Aux.FunctionDefinition.unused)); |
| if (UseBigObj) |
| WriteZeros(COFF::Symbol32Size - COFF::Symbol16Size); |
| break; |
| case ATbfAndefSymbol: |
| WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused1)); |
| writeLE16(i->Aux.bfAndefSymbol.Linenumber); |
| WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused2)); |
| writeLE32(i->Aux.bfAndefSymbol.PointerToNextFunction); |
| WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused3)); |
| if (UseBigObj) |
| WriteZeros(COFF::Symbol32Size - COFF::Symbol16Size); |
| break; |
| case ATWeakExternal: |
| writeLE32(i->Aux.WeakExternal.TagIndex); |
| writeLE32(i->Aux.WeakExternal.Characteristics); |
| WriteZeros(sizeof(i->Aux.WeakExternal.unused)); |
| if (UseBigObj) |
| WriteZeros(COFF::Symbol32Size - COFF::Symbol16Size); |
| break; |
| case ATFile: |
| writeBytes( |
| StringRef(reinterpret_cast<const char *>(&i->Aux), |
| UseBigObj ? COFF::Symbol32Size : COFF::Symbol16Size)); |
| break; |
| case ATSectionDefinition: |
| writeLE32(i->Aux.SectionDefinition.Length); |
| writeLE16(i->Aux.SectionDefinition.NumberOfRelocations); |
| writeLE16(i->Aux.SectionDefinition.NumberOfLinenumbers); |
| writeLE32(i->Aux.SectionDefinition.CheckSum); |
| writeLE16(static_cast<int16_t>(i->Aux.SectionDefinition.Number)); |
| write8(i->Aux.SectionDefinition.Selection); |
| WriteZeros(sizeof(i->Aux.SectionDefinition.unused)); |
| writeLE16(static_cast<int16_t>(i->Aux.SectionDefinition.Number >> 16)); |
| if (UseBigObj) |
| WriteZeros(COFF::Symbol32Size - COFF::Symbol16Size); |
| break; |
| } |
| } |
| } |
| |
| void WinCOFFObjectWriter::writeSectionHeader(const COFF::section &S) { |
| writeBytes(StringRef(S.Name, COFF::NameSize)); |
| |
| writeLE32(S.VirtualSize); |
| writeLE32(S.VirtualAddress); |
| writeLE32(S.SizeOfRawData); |
| writeLE32(S.PointerToRawData); |
| writeLE32(S.PointerToRelocations); |
| writeLE32(S.PointerToLineNumbers); |
| writeLE16(S.NumberOfRelocations); |
| writeLE16(S.NumberOfLineNumbers); |
| writeLE32(S.Characteristics); |
| } |
| |
| void WinCOFFObjectWriter::WriteRelocation(const COFF::relocation &R) { |
| writeLE32(R.VirtualAddress); |
| writeLE32(R.SymbolTableIndex); |
| writeLE16(R.Type); |
| } |
| |
| //////////////////////////////////////////////////////////////////////////////// |
| // MCObjectWriter interface implementations |
| |
| void WinCOFFObjectWriter::executePostLayoutBinding(MCAssembler &Asm, |
| const MCAsmLayout &Layout) { |
| // "Define" each section & symbol. This creates section & symbol |
| // entries in the staging area. |
| for (const auto &Section : Asm) |
| defineSection(static_cast<const MCSectionCOFF &>(Section)); |
| |
| for (const MCSymbol &Symbol : Asm.symbols()) |
| if (ExportSymbol(Symbol, Asm)) |
| DefineSymbol(Symbol, Asm, Layout); |
| } |
| |
| bool WinCOFFObjectWriter::isSymbolRefDifferenceFullyResolvedImpl( |
| const MCAssembler &Asm, const MCSymbol &SymA, const MCFragment &FB, |
| bool InSet, bool IsPCRel) const { |
| // MS LINK expects to be able to replace all references to a function with a |
| // thunk to implement their /INCREMENTAL feature. Make sure we don't optimize |
| // away any relocations to functions. |
| uint16_t Type = cast<MCSymbolCOFF>(SymA).getType(); |
| if ((Type >> COFF::SCT_COMPLEX_TYPE_SHIFT) == COFF::IMAGE_SYM_DTYPE_FUNCTION) |
| return false; |
| return MCObjectWriter::isSymbolRefDifferenceFullyResolvedImpl(Asm, SymA, FB, |
| InSet, IsPCRel); |
| } |
| |
| bool WinCOFFObjectWriter::isWeak(const MCSymbol &Sym) const { |
| if (!Sym.isExternal()) |
| return false; |
| |
| if (!Sym.isInSection()) |
| return false; |
| |
| const auto &Sec = cast<MCSectionCOFF>(Sym.getSection()); |
| if (!Sec.getCOMDATSymbol()) |
| return false; |
| |
| // It looks like for COFF it is invalid to replace a reference to a global |
| // in a comdat with a reference to a local. |
| // FIXME: Add a specification reference if available. |
| return true; |
| } |
| |
| void WinCOFFObjectWriter::recordRelocation( |
| MCAssembler &Asm, const MCAsmLayout &Layout, const MCFragment *Fragment, |
| const MCFixup &Fixup, MCValue Target, bool &IsPCRel, uint64_t &FixedValue) { |
| assert(Target.getSymA() && "Relocation must reference a symbol!"); |
| |
| const MCSymbol &Symbol = Target.getSymA()->getSymbol(); |
| const MCSymbol &A = Symbol; |
| if (!A.isRegistered()) |
| Asm.getContext().reportFatalError(Fixup.getLoc(), |
| Twine("symbol '") + A.getName() + |
| "' can not be undefined"); |
| |
| MCSection *Section = Fragment->getParent(); |
| |
| // Mark this symbol as requiring an entry in the symbol table. |
| assert(SectionMap.find(Section) != SectionMap.end() && |
| "Section must already have been defined in executePostLayoutBinding!"); |
| assert(SymbolMap.find(&A) != SymbolMap.end() && |
| "Symbol must already have been defined in executePostLayoutBinding!"); |
| |
| COFFSection *coff_section = SectionMap[Section]; |
| COFFSymbol *coff_symbol = SymbolMap[&A]; |
| const MCSymbolRefExpr *SymB = Target.getSymB(); |
| bool CrossSection = false; |
| |
| if (SymB) { |
| const MCSymbol *B = &SymB->getSymbol(); |
| if (!B->getFragment()) |
| Asm.getContext().reportFatalError( |
| Fixup.getLoc(), |
| Twine("symbol '") + B->getName() + |
| "' can not be undefined in a subtraction expression"); |
| |
| if (!A.getFragment()) |
| Asm.getContext().reportFatalError( |
| Fixup.getLoc(), |
| Twine("symbol '") + Symbol.getName() + |
| "' can not be undefined in a subtraction expression"); |
| |
| CrossSection = &Symbol.getSection() != &B->getSection(); |
| |
| // Offset of the symbol in the section |
| int64_t OffsetOfB = Layout.getSymbolOffset(*B); |
| |
| // In the case where we have SymbA and SymB, we just need to store the delta |
| // between the two symbols. Update FixedValue to account for the delta, and |
| // skip recording the relocation. |
| if (!CrossSection) { |
| int64_t OffsetOfA = Layout.getSymbolOffset(A); |
| FixedValue = (OffsetOfA - OffsetOfB) + Target.getConstant(); |
| return; |
| } |
| |
| // Offset of the relocation in the section |
| int64_t OffsetOfRelocation = |
| Layout.getFragmentOffset(Fragment) + Fixup.getOffset(); |
| |
| FixedValue = (OffsetOfRelocation - OffsetOfB) + Target.getConstant(); |
| } else { |
| FixedValue = Target.getConstant(); |
| } |
| |
| COFFRelocation Reloc; |
| |
| Reloc.Data.SymbolTableIndex = 0; |
| Reloc.Data.VirtualAddress = Layout.getFragmentOffset(Fragment); |
| |
| // Turn relocations for temporary symbols into section relocations. |
| if (coff_symbol->MC->isTemporary() || CrossSection) { |
| Reloc.Symb = coff_symbol->Section->Symbol; |
| FixedValue += Layout.getFragmentOffset(coff_symbol->MC->getFragment()) + |
| coff_symbol->MC->getOffset(); |
| } else |
| Reloc.Symb = coff_symbol; |
| |
| ++Reloc.Symb->Relocations; |
| |
| Reloc.Data.VirtualAddress += Fixup.getOffset(); |
| Reloc.Data.Type = TargetObjectWriter->getRelocType( |
| Target, Fixup, CrossSection, Asm.getBackend()); |
| |
| // FIXME: Can anyone explain what this does other than adjust for the size |
| // of the offset? |
| if ((Header.Machine == COFF::IMAGE_FILE_MACHINE_AMD64 && |
| Reloc.Data.Type == COFF::IMAGE_REL_AMD64_REL32) || |
| (Header.Machine == COFF::IMAGE_FILE_MACHINE_I386 && |
| Reloc.Data.Type == COFF::IMAGE_REL_I386_REL32)) |
| FixedValue += 4; |
| |
| if (Header.Machine == COFF::IMAGE_FILE_MACHINE_ARMNT) { |
| switch (Reloc.Data.Type) { |
| case COFF::IMAGE_REL_ARM_ABSOLUTE: |
| case COFF::IMAGE_REL_ARM_ADDR32: |
| case COFF::IMAGE_REL_ARM_ADDR32NB: |
| case COFF::IMAGE_REL_ARM_TOKEN: |
| case COFF::IMAGE_REL_ARM_SECTION: |
| case COFF::IMAGE_REL_ARM_SECREL: |
| break; |
| case COFF::IMAGE_REL_ARM_BRANCH11: |
| case COFF::IMAGE_REL_ARM_BLX11: |
| // IMAGE_REL_ARM_BRANCH11 and IMAGE_REL_ARM_BLX11 are only used for |
| // pre-ARMv7, which implicitly rules it out of ARMNT (it would be valid |
| // for Windows CE). |
| case COFF::IMAGE_REL_ARM_BRANCH24: |
| case COFF::IMAGE_REL_ARM_BLX24: |
| case COFF::IMAGE_REL_ARM_MOV32A: |
| // IMAGE_REL_ARM_BRANCH24, IMAGE_REL_ARM_BLX24, IMAGE_REL_ARM_MOV32A are |
| // only used for ARM mode code, which is documented as being unsupported |
| // by Windows on ARM. Empirical proof indicates that masm is able to |
| // generate the relocations however the rest of the MSVC toolchain is |
| // unable to handle it. |
| llvm_unreachable("unsupported relocation"); |
| break; |
| case COFF::IMAGE_REL_ARM_MOV32T: |
| break; |
| case COFF::IMAGE_REL_ARM_BRANCH20T: |
| case COFF::IMAGE_REL_ARM_BRANCH24T: |
| case COFF::IMAGE_REL_ARM_BLX23T: |
| // IMAGE_REL_BRANCH20T, IMAGE_REL_ARM_BRANCH24T, IMAGE_REL_ARM_BLX23T all |
| // perform a 4 byte adjustment to the relocation. Relative branches are |
| // offset by 4 on ARM, however, because there is no RELA relocations, all |
| // branches are offset by 4. |
| FixedValue = FixedValue + 4; |
| break; |
| } |
| } |
| |
| if (TargetObjectWriter->recordRelocation(Fixup)) |
| coff_section->Relocations.push_back(Reloc); |
| } |
| |
| void WinCOFFObjectWriter::writeObject(MCAssembler &Asm, |
| const MCAsmLayout &Layout) { |
| size_t SectionsSize = Sections.size(); |
| if (SectionsSize > static_cast<size_t>(INT32_MAX)) |
| report_fatal_error( |
| "PE COFF object files can't have more than 2147483647 sections"); |
| |
| // Assign symbol and section indexes and offsets. |
| int32_t NumberOfSections = static_cast<int32_t>(SectionsSize); |
| |
| UseBigObj = NumberOfSections > COFF::MaxNumberOfSections16; |
| |
| // Assign section numbers. |
| size_t Number = 1; |
| for (const auto &Section : Sections) { |
| Section->Number = Number; |
| Section->Symbol->Data.SectionNumber = Number; |
| Section->Symbol->Aux[0].Aux.SectionDefinition.Number = Number; |
| ++Number; |
| } |
| |
| Header.NumberOfSections = NumberOfSections; |
| Header.NumberOfSymbols = 0; |
| |
| for (const std::string &Name : Asm.getFileNames()) { |
| // round up to calculate the number of auxiliary symbols required |
| unsigned SymbolSize = UseBigObj ? COFF::Symbol32Size : COFF::Symbol16Size; |
| unsigned Count = (Name.size() + SymbolSize - 1) / SymbolSize; |
| |
| COFFSymbol *file = createSymbol(".file"); |
| file->Data.SectionNumber = COFF::IMAGE_SYM_DEBUG; |
| file->Data.StorageClass = COFF::IMAGE_SYM_CLASS_FILE; |
| file->Aux.resize(Count); |
| |
| unsigned Offset = 0; |
| unsigned Length = Name.size(); |
| for (auto &Aux : file->Aux) { |
| Aux.AuxType = ATFile; |
| |
| if (Length > SymbolSize) { |
| memcpy(&Aux.Aux, Name.c_str() + Offset, SymbolSize); |
| Length = Length - SymbolSize; |
| } else { |
| memcpy(&Aux.Aux, Name.c_str() + Offset, Length); |
| memset((char *)&Aux.Aux + Length, 0, SymbolSize - Length); |
| break; |
| } |
| |
| Offset += SymbolSize; |
| } |
| } |
| |
| for (auto &Symbol : Symbols) { |
| // Update section number & offset for symbols that have them. |
| if (Symbol->Section) |
| Symbol->Data.SectionNumber = Symbol->Section->Number; |
| if (Symbol->should_keep()) { |
| Symbol->setIndex(Header.NumberOfSymbols++); |
| // Update auxiliary symbol info. |
| Symbol->Data.NumberOfAuxSymbols = Symbol->Aux.size(); |
| Header.NumberOfSymbols += Symbol->Data.NumberOfAuxSymbols; |
| } else { |
| Symbol->setIndex(-1); |
| } |
| } |
| |
| // Build string table. |
| for (const auto &S : Sections) |
| if (S->Name.size() > COFF::NameSize) |
| Strings.add(S->Name); |
| for (const auto &S : Symbols) |
| if (S->should_keep() && S->Name.size() > COFF::NameSize) |
| Strings.add(S->Name); |
| Strings.finalize(StringTableBuilder::WinCOFF); |
| |
| // Set names. |
| for (const auto &S : Sections) |
| SetSectionName(*S); |
| for (auto &S : Symbols) |
| if (S->should_keep()) |
| SetSymbolName(*S); |
| |
| // Fixup weak external references. |
| for (auto &Symbol : Symbols) { |
| if (Symbol->Other) { |
| assert(Symbol->getIndex() != -1); |
| assert(Symbol->Aux.size() == 1 && "Symbol must contain one aux symbol!"); |
| assert(Symbol->Aux[0].AuxType == ATWeakExternal && |
| "Symbol's aux symbol must be a Weak External!"); |
| Symbol->Aux[0].Aux.WeakExternal.TagIndex = Symbol->Other->getIndex(); |
| } |
| } |
| |
| // Fixup associative COMDAT sections. |
| for (auto &Section : Sections) { |
| if (Section->Symbol->Aux[0].Aux.SectionDefinition.Selection != |
| COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) |
| continue; |
| |
| const MCSectionCOFF &MCSec = *Section->MCSection; |
| |
| const MCSymbol *COMDAT = MCSec.getCOMDATSymbol(); |
| assert(COMDAT); |
| COFFSymbol *COMDATSymbol = GetOrCreateCOFFSymbol(COMDAT); |
| assert(COMDATSymbol); |
| COFFSection *Assoc = COMDATSymbol->Section; |
| if (!Assoc) |
| report_fatal_error( |
| Twine("Missing associated COMDAT section for section ") + |
| MCSec.getSectionName()); |
| |
| // Skip this section if the associated section is unused. |
| if (Assoc->Number == -1) |
| continue; |
| |
| Section->Symbol->Aux[0].Aux.SectionDefinition.Number = Assoc->Number; |
| } |
| |
| // Assign file offsets to COFF object file structures. |
| |
| unsigned offset = 0; |
| |
| if (UseBigObj) |
| offset += COFF::Header32Size; |
| else |
| offset += COFF::Header16Size; |
| offset += COFF::SectionSize * Header.NumberOfSections; |
| |
| for (const auto &Section : Asm) { |
| COFFSection *Sec = SectionMap[&Section]; |
| |
| if (Sec->Number == -1) |
| continue; |
| |
| Sec->Header.SizeOfRawData = Layout.getSectionAddressSize(&Section); |
| |
| if (IsPhysicalSection(Sec)) { |
| // Align the section data to a four byte boundary. |
| offset = RoundUpToAlignment(offset, 4); |
| Sec->Header.PointerToRawData = offset; |
| |
| offset += Sec->Header.SizeOfRawData; |
| } |
| |
| if (Sec->Relocations.size() > 0) { |
| bool RelocationsOverflow = Sec->Relocations.size() >= 0xffff; |
| |
| if (RelocationsOverflow) { |
| // Signal overflow by setting NumberOfRelocations to max value. Actual |
| // size is found in reloc #0. Microsoft tools understand this. |
| Sec->Header.NumberOfRelocations = 0xffff; |
| } else { |
| Sec->Header.NumberOfRelocations = Sec->Relocations.size(); |
| } |
| Sec->Header.PointerToRelocations = offset; |
| |
| if (RelocationsOverflow) { |
| // Reloc #0 will contain actual count, so make room for it. |
| offset += COFF::RelocationSize; |
| } |
| |
| offset += COFF::RelocationSize * Sec->Relocations.size(); |
| |
| for (auto &Relocation : Sec->Relocations) { |
| assert(Relocation.Symb->getIndex() != -1); |
| Relocation.Data.SymbolTableIndex = Relocation.Symb->getIndex(); |
| } |
| } |
| |
| assert(Sec->Symbol->Aux.size() == 1 && |
| "Section's symbol must have one aux!"); |
| AuxSymbol &Aux = Sec->Symbol->Aux[0]; |
| assert(Aux.AuxType == ATSectionDefinition && |
| "Section's symbol's aux symbol must be a Section Definition!"); |
| Aux.Aux.SectionDefinition.Length = Sec->Header.SizeOfRawData; |
| Aux.Aux.SectionDefinition.NumberOfRelocations = |
| Sec->Header.NumberOfRelocations; |
| Aux.Aux.SectionDefinition.NumberOfLinenumbers = |
| Sec->Header.NumberOfLineNumbers; |
| } |
| |
| Header.PointerToSymbolTable = offset; |
| |
| // We want a deterministic output. It looks like GNU as also writes 0 in here. |
| Header.TimeDateStamp = 0; |
| |
| // Write it all to disk... |
| WriteFileHeader(Header); |
| |
| { |
| sections::iterator i, ie; |
| MCAssembler::iterator j, je; |
| |
| for (auto &Section : Sections) { |
| if (Section->Number != -1) { |
| if (Section->Relocations.size() >= 0xffff) |
| Section->Header.Characteristics |= COFF::IMAGE_SCN_LNK_NRELOC_OVFL; |
| writeSectionHeader(Section->Header); |
| } |
| } |
| |
| for (i = Sections.begin(), ie = Sections.end(), j = Asm.begin(), |
| je = Asm.end(); |
| (i != ie) && (j != je); ++i, ++j) { |
| |
| if ((*i)->Number == -1) |
| continue; |
| |
| if ((*i)->Header.PointerToRawData != 0) { |
| assert(OS.tell() <= (*i)->Header.PointerToRawData && |
| "Section::PointerToRawData is insane!"); |
| |
| unsigned SectionDataPadding = (*i)->Header.PointerToRawData - OS.tell(); |
| assert(SectionDataPadding < 4 && |
| "Should only need at most three bytes of padding!"); |
| |
| WriteZeros(SectionDataPadding); |
| |
| Asm.writeSectionData(&*j, Layout); |
| } |
| |
| if ((*i)->Relocations.size() > 0) { |
| assert(OS.tell() == (*i)->Header.PointerToRelocations && |
| "Section::PointerToRelocations is insane!"); |
| |
| if ((*i)->Relocations.size() >= 0xffff) { |
| // In case of overflow, write actual relocation count as first |
| // relocation. Including the synthetic reloc itself (+ 1). |
| COFF::relocation r; |
| r.VirtualAddress = (*i)->Relocations.size() + 1; |
| r.SymbolTableIndex = 0; |
| r.Type = 0; |
| WriteRelocation(r); |
| } |
| |
| for (const auto &Relocation : (*i)->Relocations) |
| WriteRelocation(Relocation.Data); |
| } else |
| assert((*i)->Header.PointerToRelocations == 0 && |
| "Section::PointerToRelocations is insane!"); |
| } |
| } |
| |
| assert(OS.tell() == Header.PointerToSymbolTable && |
| "Header::PointerToSymbolTable is insane!"); |
| |
| for (auto &Symbol : Symbols) |
| if (Symbol->getIndex() != -1) |
| WriteSymbol(*Symbol); |
| |
| OS.write(Strings.data().data(), Strings.data().size()); |
| } |
| |
| MCWinCOFFObjectTargetWriter::MCWinCOFFObjectTargetWriter(unsigned Machine_) |
| : Machine(Machine_) {} |
| |
| // Pin the vtable to this file. |
| void MCWinCOFFObjectTargetWriter::anchor() {} |
| |
| //------------------------------------------------------------------------------ |
| // WinCOFFObjectWriter factory function |
| |
| MCObjectWriter * |
| llvm::createWinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW, |
| raw_pwrite_stream &OS) { |
| return new WinCOFFObjectWriter(MOTW, OS); |
| } |