diff options
Diffstat (limited to 'contrib/llvm/lib/MC/WinCOFFObjectWriter.cpp')
| -rw-r--r-- | contrib/llvm/lib/MC/WinCOFFObjectWriter.cpp | 1098 |
1 files changed, 1098 insertions, 0 deletions
diff --git a/contrib/llvm/lib/MC/WinCOFFObjectWriter.cpp b/contrib/llvm/lib/MC/WinCOFFObjectWriter.cpp new file mode 100644 index 0000000..a382090 --- /dev/null +++ b/contrib/llvm/lib/MC/WinCOFFObjectWriter.cpp @@ -0,0 +1,1098 @@ +//===-- 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/Config/config.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/JamCRC.h" +#include "llvm/Support/TimeValue.h" +#include <cstdio> +#include <ctime> + +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); + + 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{StringTableBuilder::WinCOFF}; + + // 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 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); +} + +//------------------------------------------------------------------------------ +// 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); + + 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::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 (!Symbol.isTemporary()) + 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 (Asm.isIncrementalLinkerCompatible() && + (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 &A = Target.getSymA()->getSymbol(); + if (!A.isRegistered()) { + Asm.getContext().reportError(Fixup.getLoc(), + Twine("symbol '") + A.getName() + + "' can not be undefined"); + return; + } + if (A.isTemporary() && A.isUndefined()) { + Asm.getContext().reportError(Fixup.getLoc(), + Twine("assembler label '") + A.getName() + + "' can not be undefined"); + return; + } + + 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!"); + + COFFSection *coff_section = SectionMap[Section]; + const MCSymbolRefExpr *SymB = Target.getSymB(); + bool CrossSection = false; + + if (SymB) { + const MCSymbol *B = &SymB->getSymbol(); + if (!B->getFragment()) { + Asm.getContext().reportError( + Fixup.getLoc(), + Twine("symbol '") + B->getName() + + "' can not be undefined in a subtraction expression"); + return; + } + + if (!A.getFragment()) { + Asm.getContext().reportError( + Fixup.getLoc(), + Twine("symbol '") + A.getName() + + "' can not be undefined in a subtraction expression"); + return; + } + + CrossSection = &A.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 (A.isTemporary() || CrossSection) { + MCSection *TargetSection = &A.getSection(); + assert( + SectionMap.find(TargetSection) != SectionMap.end() && + "Section must already have been defined in executePostLayoutBinding!"); + Reloc.Symb = SectionMap[TargetSection]->Symbol; + FixedValue += Layout.getSymbolOffset(A); + } else { + assert( + SymbolMap.find(&A) != SymbolMap.end() && + "Symbol must already have been defined in executePostLayoutBinding!"); + Reloc.Symb = SymbolMap[&A]; + } + + ++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; + Symbol->setIndex(Header.NumberOfSymbols++); + // Update auxiliary symbol info. + Symbol->Data.NumberOfAuxSymbols = Symbol->Aux.size(); + Header.NumberOfSymbols += Symbol->Data.NumberOfAuxSymbols; + } + + // 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->Name.size() > COFF::NameSize) + Strings.add(S->Name); + Strings.finalize(); + + // Set names. + for (const auto &S : Sections) + SetSectionName(*S); + for (auto &S : Symbols) + 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 = getInitialOffset(); + + 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; + + // FIXME: Remove the #else branch and make the #if branch unconditional once + // LLVM's self host configuration is aware of /Brepro. +#if (ENABLE_TIMESTAMPS == 1) + // MS LINK expects to be able to use this timestamp to implement their + // /INCREMENTAL feature. + if (Asm.isIncrementalLinkerCompatible()) { + std::time_t Now = time(nullptr); + if (Now < 0 || !isUInt<32>(Now)) + Now = UINT32_MAX; + Header.TimeDateStamp = Now; + } else { + Header.TimeDateStamp = 0; + } +#else + // We want a deterministic output. It looks like GNU as also writes 0 in here. + Header.TimeDateStamp = 0; +#endif + + // 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); + } + } + + SmallVector<char, 128> SectionContents; + 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(getStream().tell() <= (*i)->Header.PointerToRawData && + "Section::PointerToRawData is insane!"); + + unsigned SectionDataPadding = + (*i)->Header.PointerToRawData - getStream().tell(); + assert(SectionDataPadding < 4 && + "Should only need at most three bytes of padding!"); + + WriteZeros(SectionDataPadding); + + // Save the contents of the section to a temporary buffer, we need this + // to CRC the data before we dump it into the object file. + SectionContents.clear(); + raw_svector_ostream VecOS(SectionContents); + raw_pwrite_stream &OldStream = getStream(); + // Redirect the output stream to our buffer. + setStream(VecOS); + // Fill our buffer with the section data. + Asm.writeSectionData(&*j, Layout); + // Reset the stream back to what it was before. + setStream(OldStream); + + // Calculate our CRC with an initial value of '0', this is not how + // JamCRC is specified but it aligns with the expected output. + JamCRC JC(/*Init=*/0x00000000U); + JC.update(SectionContents); + + // Write the section contents to the object file. + getStream() << SectionContents; + + // Update the section definition auxiliary symbol to record the CRC. + COFFSection *Sec = SectionMap[&*j]; + COFFSymbol::AuxiliarySymbols &AuxSyms = Sec->Symbol->Aux; + assert(AuxSyms.size() == 1 && + AuxSyms[0].AuxType == ATSectionDefinition); + AuxSymbol &SecDef = AuxSyms[0]; + SecDef.Aux.SectionDefinition.CheckSum = JC.getCRC(); + } + + if ((*i)->Relocations.size() > 0) { + assert(getStream().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(getStream().tell() == Header.PointerToSymbolTable && + "Header::PointerToSymbolTable is insane!"); + + for (auto &Symbol : Symbols) + if (Symbol->getIndex() != -1) + WriteSymbol(*Symbol); + + getStream().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); +} |
