1104 lines
37 KiB
C++
1104 lines
37 KiB
C++
//===- llvm/MC/WinCOFFObjectWriter.cpp ------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains an implementation of a Win32 COFF object file writer.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/SmallString.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/BinaryFormat/COFF.h"
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#include "llvm/MC/MCAsmLayout.h"
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#include "llvm/MC/MCAssembler.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCExpr.h"
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#include "llvm/MC/MCFixup.h"
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#include "llvm/MC/MCFragment.h"
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#include "llvm/MC/MCObjectWriter.h"
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#include "llvm/MC/MCSection.h"
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#include "llvm/MC/MCSectionCOFF.h"
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#include "llvm/MC/MCSymbol.h"
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#include "llvm/MC/MCSymbolCOFF.h"
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#include "llvm/MC/MCValue.h"
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#include "llvm/MC/MCWinCOFFObjectWriter.h"
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#include "llvm/MC/StringTableBuilder.h"
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#include "llvm/Support/Casting.h"
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#include "llvm/Support/Endian.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/JamCRC.h"
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#include "llvm/Support/LEB128.h"
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#include "llvm/Support/MathExtras.h"
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#include "llvm/Support/raw_ostream.h"
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#include <algorithm>
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#include <cassert>
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#include <cstddef>
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#include <cstdint>
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#include <cstring>
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#include <ctime>
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#include <memory>
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#include <string>
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#include <vector>
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using namespace llvm;
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using llvm::support::endian::write32le;
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#define DEBUG_TYPE "WinCOFFObjectWriter"
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namespace {
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using name = SmallString<COFF::NameSize>;
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enum AuxiliaryType {
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ATWeakExternal,
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ATFile,
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ATSectionDefinition
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};
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struct AuxSymbol {
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AuxiliaryType AuxType;
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COFF::Auxiliary Aux;
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};
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class COFFSection;
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class COFFSymbol {
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public:
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COFF::symbol Data = {};
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using AuxiliarySymbols = SmallVector<AuxSymbol, 1>;
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name Name;
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int Index;
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AuxiliarySymbols Aux;
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COFFSymbol *Other = nullptr;
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COFFSection *Section = nullptr;
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int Relocations = 0;
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const MCSymbol *MC = nullptr;
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COFFSymbol(StringRef Name) : Name(Name) {}
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void set_name_offset(uint32_t Offset);
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int64_t getIndex() const { return Index; }
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void setIndex(int Value) {
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Index = Value;
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if (MC)
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MC->setIndex(static_cast<uint32_t>(Value));
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}
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};
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// This class contains staging data for a COFF relocation entry.
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struct COFFRelocation {
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COFF::relocation Data;
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COFFSymbol *Symb = nullptr;
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COFFRelocation() = default;
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static size_t size() { return COFF::RelocationSize; }
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};
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using relocations = std::vector<COFFRelocation>;
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class COFFSection {
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public:
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COFF::section Header = {};
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std::string Name;
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int Number;
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MCSectionCOFF const *MCSection = nullptr;
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COFFSymbol *Symbol = nullptr;
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relocations Relocations;
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COFFSection(StringRef Name) : Name(Name) {}
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};
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class WinCOFFObjectWriter : public MCObjectWriter {
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public:
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support::endian::Writer W;
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using symbols = std::vector<std::unique_ptr<COFFSymbol>>;
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using sections = std::vector<std::unique_ptr<COFFSection>>;
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using symbol_map = DenseMap<MCSymbol const *, COFFSymbol *>;
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using section_map = DenseMap<MCSection const *, COFFSection *>;
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std::unique_ptr<MCWinCOFFObjectTargetWriter> TargetObjectWriter;
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// Root level file contents.
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COFF::header Header = {};
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sections Sections;
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symbols Symbols;
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StringTableBuilder Strings{StringTableBuilder::WinCOFF};
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// Maps used during object file creation.
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section_map SectionMap;
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symbol_map SymbolMap;
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bool UseBigObj;
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bool EmitAddrsigSection = false;
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MCSectionCOFF *AddrsigSection;
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std::vector<const MCSymbol *> AddrsigSyms;
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WinCOFFObjectWriter(std::unique_ptr<MCWinCOFFObjectTargetWriter> MOTW,
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raw_pwrite_stream &OS);
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void reset() override {
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memset(&Header, 0, sizeof(Header));
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Header.Machine = TargetObjectWriter->getMachine();
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Sections.clear();
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Symbols.clear();
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Strings.clear();
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SectionMap.clear();
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SymbolMap.clear();
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MCObjectWriter::reset();
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}
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COFFSymbol *createSymbol(StringRef Name);
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COFFSymbol *GetOrCreateCOFFSymbol(const MCSymbol *Symbol);
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COFFSection *createSection(StringRef Name);
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void defineSection(MCSectionCOFF const &Sec);
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COFFSymbol *getLinkedSymbol(const MCSymbol &Symbol);
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void DefineSymbol(const MCSymbol &Symbol, MCAssembler &Assembler,
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const MCAsmLayout &Layout);
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void SetSymbolName(COFFSymbol &S);
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void SetSectionName(COFFSection &S);
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bool IsPhysicalSection(COFFSection *S);
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// Entity writing methods.
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void WriteFileHeader(const COFF::header &Header);
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void WriteSymbol(const COFFSymbol &S);
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void WriteAuxiliarySymbols(const COFFSymbol::AuxiliarySymbols &S);
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void writeSectionHeaders();
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void WriteRelocation(const COFF::relocation &R);
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uint32_t writeSectionContents(MCAssembler &Asm, const MCAsmLayout &Layout,
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const MCSection &MCSec);
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void writeSection(MCAssembler &Asm, const MCAsmLayout &Layout,
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const COFFSection &Sec, const MCSection &MCSec);
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// MCObjectWriter interface implementation.
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void executePostLayoutBinding(MCAssembler &Asm,
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const MCAsmLayout &Layout) override;
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bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
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const MCSymbol &SymA,
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const MCFragment &FB, bool InSet,
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bool IsPCRel) const override;
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void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
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const MCFragment *Fragment, const MCFixup &Fixup,
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MCValue Target, uint64_t &FixedValue) override;
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void createFileSymbols(MCAssembler &Asm);
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void assignSectionNumbers();
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void assignFileOffsets(MCAssembler &Asm, const MCAsmLayout &Layout);
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void emitAddrsigSection() override { EmitAddrsigSection = true; }
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void addAddrsigSymbol(const MCSymbol *Sym) override {
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AddrsigSyms.push_back(Sym);
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}
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uint64_t writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
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};
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} // end anonymous namespace
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//------------------------------------------------------------------------------
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// Symbol class implementation
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// In the case that the name does not fit within 8 bytes, the offset
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// into the string table is stored in the last 4 bytes instead, leaving
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// the first 4 bytes as 0.
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void COFFSymbol::set_name_offset(uint32_t Offset) {
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write32le(Data.Name + 0, 0);
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write32le(Data.Name + 4, Offset);
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}
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//------------------------------------------------------------------------------
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// WinCOFFObjectWriter class implementation
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WinCOFFObjectWriter::WinCOFFObjectWriter(
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std::unique_ptr<MCWinCOFFObjectTargetWriter> MOTW, raw_pwrite_stream &OS)
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: W(OS, support::little), TargetObjectWriter(std::move(MOTW)) {
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Header.Machine = TargetObjectWriter->getMachine();
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}
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COFFSymbol *WinCOFFObjectWriter::createSymbol(StringRef Name) {
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Symbols.push_back(make_unique<COFFSymbol>(Name));
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return Symbols.back().get();
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}
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COFFSymbol *WinCOFFObjectWriter::GetOrCreateCOFFSymbol(const MCSymbol *Symbol) {
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COFFSymbol *&Ret = SymbolMap[Symbol];
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if (!Ret)
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Ret = createSymbol(Symbol->getName());
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return Ret;
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}
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COFFSection *WinCOFFObjectWriter::createSection(StringRef Name) {
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Sections.emplace_back(make_unique<COFFSection>(Name));
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return Sections.back().get();
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}
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static uint32_t getAlignment(const MCSectionCOFF &Sec) {
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switch (Sec.getAlignment()) {
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case 1:
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return COFF::IMAGE_SCN_ALIGN_1BYTES;
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case 2:
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return COFF::IMAGE_SCN_ALIGN_2BYTES;
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case 4:
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return COFF::IMAGE_SCN_ALIGN_4BYTES;
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case 8:
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return COFF::IMAGE_SCN_ALIGN_8BYTES;
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case 16:
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return COFF::IMAGE_SCN_ALIGN_16BYTES;
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case 32:
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return COFF::IMAGE_SCN_ALIGN_32BYTES;
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case 64:
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return COFF::IMAGE_SCN_ALIGN_64BYTES;
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case 128:
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return COFF::IMAGE_SCN_ALIGN_128BYTES;
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case 256:
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return COFF::IMAGE_SCN_ALIGN_256BYTES;
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case 512:
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return COFF::IMAGE_SCN_ALIGN_512BYTES;
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case 1024:
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return COFF::IMAGE_SCN_ALIGN_1024BYTES;
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case 2048:
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return COFF::IMAGE_SCN_ALIGN_2048BYTES;
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case 4096:
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return COFF::IMAGE_SCN_ALIGN_4096BYTES;
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case 8192:
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return COFF::IMAGE_SCN_ALIGN_8192BYTES;
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}
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llvm_unreachable("unsupported section alignment");
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}
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/// This function takes a section data object from the assembler
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/// and creates the associated COFF section staging object.
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void WinCOFFObjectWriter::defineSection(const MCSectionCOFF &MCSec) {
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COFFSection *Section = createSection(MCSec.getSectionName());
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COFFSymbol *Symbol = createSymbol(MCSec.getSectionName());
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Section->Symbol = Symbol;
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Symbol->Section = Section;
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Symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_STATIC;
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// Create a COMDAT symbol if needed.
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if (MCSec.getSelection() != COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
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if (const MCSymbol *S = MCSec.getCOMDATSymbol()) {
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COFFSymbol *COMDATSymbol = GetOrCreateCOFFSymbol(S);
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if (COMDATSymbol->Section)
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report_fatal_error("two sections have the same comdat");
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COMDATSymbol->Section = Section;
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}
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}
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// In this case the auxiliary symbol is a Section Definition.
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Symbol->Aux.resize(1);
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Symbol->Aux[0] = {};
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Symbol->Aux[0].AuxType = ATSectionDefinition;
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Symbol->Aux[0].Aux.SectionDefinition.Selection = MCSec.getSelection();
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// Set section alignment.
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Section->Header.Characteristics = MCSec.getCharacteristics();
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Section->Header.Characteristics |= getAlignment(MCSec);
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// Bind internal COFF section to MC section.
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Section->MCSection = &MCSec;
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SectionMap[&MCSec] = Section;
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}
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static uint64_t getSymbolValue(const MCSymbol &Symbol,
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const MCAsmLayout &Layout) {
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if (Symbol.isCommon() && Symbol.isExternal())
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return Symbol.getCommonSize();
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uint64_t Res;
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if (!Layout.getSymbolOffset(Symbol, Res))
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return 0;
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return Res;
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}
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COFFSymbol *WinCOFFObjectWriter::getLinkedSymbol(const MCSymbol &Symbol) {
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if (!Symbol.isVariable())
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return nullptr;
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const MCSymbolRefExpr *SymRef =
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dyn_cast<MCSymbolRefExpr>(Symbol.getVariableValue());
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if (!SymRef)
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return nullptr;
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const MCSymbol &Aliasee = SymRef->getSymbol();
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if (!Aliasee.isUndefined())
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return nullptr;
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return GetOrCreateCOFFSymbol(&Aliasee);
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}
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/// This function takes a symbol data object from the assembler
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/// and creates the associated COFF symbol staging object.
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void WinCOFFObjectWriter::DefineSymbol(const MCSymbol &MCSym,
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MCAssembler &Assembler,
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const MCAsmLayout &Layout) {
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COFFSymbol *Sym = GetOrCreateCOFFSymbol(&MCSym);
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const MCSymbol *Base = Layout.getBaseSymbol(MCSym);
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COFFSection *Sec = nullptr;
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if (Base && Base->getFragment()) {
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Sec = SectionMap[Base->getFragment()->getParent()];
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if (Sym->Section && Sym->Section != Sec)
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report_fatal_error("conflicting sections for symbol");
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}
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COFFSymbol *Local = nullptr;
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if (cast<MCSymbolCOFF>(MCSym).isWeakExternal()) {
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Sym->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
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COFFSymbol *WeakDefault = getLinkedSymbol(MCSym);
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if (!WeakDefault) {
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std::string WeakName = (".weak." + MCSym.getName() + ".default").str();
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WeakDefault = createSymbol(WeakName);
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if (!Sec)
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WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
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else
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WeakDefault->Section = Sec;
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Local = WeakDefault;
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}
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Sym->Other = WeakDefault;
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// Setup the Weak External auxiliary symbol.
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Sym->Aux.resize(1);
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memset(&Sym->Aux[0], 0, sizeof(Sym->Aux[0]));
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Sym->Aux[0].AuxType = ATWeakExternal;
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Sym->Aux[0].Aux.WeakExternal.TagIndex = 0;
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Sym->Aux[0].Aux.WeakExternal.Characteristics =
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COFF::IMAGE_WEAK_EXTERN_SEARCH_LIBRARY;
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} else {
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if (!Base)
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Sym->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
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else
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Sym->Section = Sec;
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Local = Sym;
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}
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if (Local) {
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Local->Data.Value = getSymbolValue(MCSym, Layout);
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const MCSymbolCOFF &SymbolCOFF = cast<MCSymbolCOFF>(MCSym);
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Local->Data.Type = SymbolCOFF.getType();
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Local->Data.StorageClass = SymbolCOFF.getClass();
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// If no storage class was specified in the streamer, define it here.
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if (Local->Data.StorageClass == COFF::IMAGE_SYM_CLASS_NULL) {
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bool IsExternal = MCSym.isExternal() ||
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(!MCSym.getFragment() && !MCSym.isVariable());
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Local->Data.StorageClass = IsExternal ? COFF::IMAGE_SYM_CLASS_EXTERNAL
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: COFF::IMAGE_SYM_CLASS_STATIC;
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}
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}
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Sym->MC = &MCSym;
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}
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// Maximum offsets for different string table entry encodings.
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enum : unsigned { Max7DecimalOffset = 9999999U };
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enum : uint64_t { MaxBase64Offset = 0xFFFFFFFFFULL }; // 64^6, including 0
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// Encode a string table entry offset in base 64, padded to 6 chars, and
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// prefixed with a double slash: '//AAAAAA', '//AAAAAB', ...
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// Buffer must be at least 8 bytes large. No terminating null appended.
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static void encodeBase64StringEntry(char *Buffer, uint64_t Value) {
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assert(Value > Max7DecimalOffset && Value <= MaxBase64Offset &&
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"Illegal section name encoding for value");
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static const char Alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
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"abcdefghijklmnopqrstuvwxyz"
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"0123456789+/";
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Buffer[0] = '/';
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Buffer[1] = '/';
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char *Ptr = Buffer + 7;
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for (unsigned i = 0; i < 6; ++i) {
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unsigned Rem = Value % 64;
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Value /= 64;
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*(Ptr--) = Alphabet[Rem];
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}
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}
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void WinCOFFObjectWriter::SetSectionName(COFFSection &S) {
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if (S.Name.size() <= COFF::NameSize) {
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std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size());
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return;
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}
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uint64_t StringTableEntry = Strings.getOffset(S.Name);
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if (StringTableEntry <= Max7DecimalOffset) {
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SmallVector<char, COFF::NameSize> Buffer;
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Twine('/').concat(Twine(StringTableEntry)).toVector(Buffer);
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assert(Buffer.size() <= COFF::NameSize && Buffer.size() >= 2);
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std::memcpy(S.Header.Name, Buffer.data(), Buffer.size());
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return;
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}
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if (StringTableEntry <= MaxBase64Offset) {
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// Starting with 10,000,000, offsets are encoded as base64.
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encodeBase64StringEntry(S.Header.Name, StringTableEntry);
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return;
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}
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report_fatal_error("COFF string table is greater than 64 GB.");
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}
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void WinCOFFObjectWriter::SetSymbolName(COFFSymbol &S) {
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if (S.Name.size() > COFF::NameSize)
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S.set_name_offset(Strings.getOffset(S.Name));
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else
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std::memcpy(S.Data.Name, S.Name.c_str(), S.Name.size());
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}
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bool WinCOFFObjectWriter::IsPhysicalSection(COFFSection *S) {
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return (S->Header.Characteristics & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) ==
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0;
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}
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//------------------------------------------------------------------------------
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// entity writing methods
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void WinCOFFObjectWriter::WriteFileHeader(const COFF::header &Header) {
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if (UseBigObj) {
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W.write<uint16_t>(COFF::IMAGE_FILE_MACHINE_UNKNOWN);
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W.write<uint16_t>(0xFFFF);
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W.write<uint16_t>(COFF::BigObjHeader::MinBigObjectVersion);
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W.write<uint16_t>(Header.Machine);
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W.write<uint32_t>(Header.TimeDateStamp);
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W.OS.write(COFF::BigObjMagic, sizeof(COFF::BigObjMagic));
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W.write<uint32_t>(0);
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W.write<uint32_t>(0);
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W.write<uint32_t>(0);
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W.write<uint32_t>(0);
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W.write<uint32_t>(Header.NumberOfSections);
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W.write<uint32_t>(Header.PointerToSymbolTable);
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W.write<uint32_t>(Header.NumberOfSymbols);
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} else {
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W.write<uint16_t>(Header.Machine);
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W.write<uint16_t>(static_cast<int16_t>(Header.NumberOfSections));
|
|
W.write<uint32_t>(Header.TimeDateStamp);
|
|
W.write<uint32_t>(Header.PointerToSymbolTable);
|
|
W.write<uint32_t>(Header.NumberOfSymbols);
|
|
W.write<uint16_t>(Header.SizeOfOptionalHeader);
|
|
W.write<uint16_t>(Header.Characteristics);
|
|
}
|
|
}
|
|
|
|
void WinCOFFObjectWriter::WriteSymbol(const COFFSymbol &S) {
|
|
W.OS.write(S.Data.Name, COFF::NameSize);
|
|
W.write<uint32_t>(S.Data.Value);
|
|
if (UseBigObj)
|
|
W.write<uint32_t>(S.Data.SectionNumber);
|
|
else
|
|
W.write<uint16_t>(static_cast<int16_t>(S.Data.SectionNumber));
|
|
W.write<uint16_t>(S.Data.Type);
|
|
W.OS << char(S.Data.StorageClass);
|
|
W.OS << char(S.Data.NumberOfAuxSymbols);
|
|
WriteAuxiliarySymbols(S.Aux);
|
|
}
|
|
|
|
void WinCOFFObjectWriter::WriteAuxiliarySymbols(
|
|
const COFFSymbol::AuxiliarySymbols &S) {
|
|
for (const AuxSymbol &i : S) {
|
|
switch (i.AuxType) {
|
|
case ATWeakExternal:
|
|
W.write<uint32_t>(i.Aux.WeakExternal.TagIndex);
|
|
W.write<uint32_t>(i.Aux.WeakExternal.Characteristics);
|
|
W.OS.write_zeros(sizeof(i.Aux.WeakExternal.unused));
|
|
if (UseBigObj)
|
|
W.OS.write_zeros(COFF::Symbol32Size - COFF::Symbol16Size);
|
|
break;
|
|
case ATFile:
|
|
W.OS.write(reinterpret_cast<const char *>(&i.Aux),
|
|
UseBigObj ? COFF::Symbol32Size : COFF::Symbol16Size);
|
|
break;
|
|
case ATSectionDefinition:
|
|
W.write<uint32_t>(i.Aux.SectionDefinition.Length);
|
|
W.write<uint16_t>(i.Aux.SectionDefinition.NumberOfRelocations);
|
|
W.write<uint16_t>(i.Aux.SectionDefinition.NumberOfLinenumbers);
|
|
W.write<uint32_t>(i.Aux.SectionDefinition.CheckSum);
|
|
W.write<uint16_t>(static_cast<int16_t>(i.Aux.SectionDefinition.Number));
|
|
W.OS << char(i.Aux.SectionDefinition.Selection);
|
|
W.OS.write_zeros(sizeof(i.Aux.SectionDefinition.unused));
|
|
W.write<uint16_t>(static_cast<int16_t>(i.Aux.SectionDefinition.Number >> 16));
|
|
if (UseBigObj)
|
|
W.OS.write_zeros(COFF::Symbol32Size - COFF::Symbol16Size);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Write the section header.
|
|
void WinCOFFObjectWriter::writeSectionHeaders() {
|
|
// Section numbers must be monotonically increasing in the section
|
|
// header, but our Sections array is not sorted by section number,
|
|
// so make a copy of Sections and sort it.
|
|
std::vector<COFFSection *> Arr;
|
|
for (auto &Section : Sections)
|
|
Arr.push_back(Section.get());
|
|
llvm::sort(Arr, [](const COFFSection *A, const COFFSection *B) {
|
|
return A->Number < B->Number;
|
|
});
|
|
|
|
for (auto &Section : Arr) {
|
|
if (Section->Number == -1)
|
|
continue;
|
|
|
|
COFF::section &S = Section->Header;
|
|
if (Section->Relocations.size() >= 0xffff)
|
|
S.Characteristics |= COFF::IMAGE_SCN_LNK_NRELOC_OVFL;
|
|
W.OS.write(S.Name, COFF::NameSize);
|
|
W.write<uint32_t>(S.VirtualSize);
|
|
W.write<uint32_t>(S.VirtualAddress);
|
|
W.write<uint32_t>(S.SizeOfRawData);
|
|
W.write<uint32_t>(S.PointerToRawData);
|
|
W.write<uint32_t>(S.PointerToRelocations);
|
|
W.write<uint32_t>(S.PointerToLineNumbers);
|
|
W.write<uint16_t>(S.NumberOfRelocations);
|
|
W.write<uint16_t>(S.NumberOfLineNumbers);
|
|
W.write<uint32_t>(S.Characteristics);
|
|
}
|
|
}
|
|
|
|
void WinCOFFObjectWriter::WriteRelocation(const COFF::relocation &R) {
|
|
W.write<uint32_t>(R.VirtualAddress);
|
|
W.write<uint32_t>(R.SymbolTableIndex);
|
|
W.write<uint16_t>(R.Type);
|
|
}
|
|
|
|
// Write MCSec's contents. What this function does is essentially
|
|
// "Asm.writeSectionData(&MCSec, Layout)", but it's a bit complicated
|
|
// because it needs to compute a CRC.
|
|
uint32_t WinCOFFObjectWriter::writeSectionContents(MCAssembler &Asm,
|
|
const MCAsmLayout &Layout,
|
|
const MCSection &MCSec) {
|
|
// 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.
|
|
SmallVector<char, 128> Buf;
|
|
raw_svector_ostream VecOS(Buf);
|
|
Asm.writeSectionData(VecOS, &MCSec, Layout);
|
|
|
|
// Write the section contents to the object file.
|
|
W.OS << Buf;
|
|
|
|
// 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=*/0);
|
|
JC.update(Buf);
|
|
return JC.getCRC();
|
|
}
|
|
|
|
void WinCOFFObjectWriter::writeSection(MCAssembler &Asm,
|
|
const MCAsmLayout &Layout,
|
|
const COFFSection &Sec,
|
|
const MCSection &MCSec) {
|
|
if (Sec.Number == -1)
|
|
return;
|
|
|
|
// Write the section contents.
|
|
if (Sec.Header.PointerToRawData != 0) {
|
|
assert(W.OS.tell() == Sec.Header.PointerToRawData &&
|
|
"Section::PointerToRawData is insane!");
|
|
|
|
uint32_t CRC = writeSectionContents(Asm, Layout, MCSec);
|
|
|
|
// Update the section definition auxiliary symbol to record the CRC.
|
|
COFFSection *Sec = SectionMap[&MCSec];
|
|
COFFSymbol::AuxiliarySymbols &AuxSyms = Sec->Symbol->Aux;
|
|
assert(AuxSyms.size() == 1 && AuxSyms[0].AuxType == ATSectionDefinition);
|
|
AuxSymbol &SecDef = AuxSyms[0];
|
|
SecDef.Aux.SectionDefinition.CheckSum = CRC;
|
|
}
|
|
|
|
// Write relocations for this section.
|
|
if (Sec.Relocations.empty()) {
|
|
assert(Sec.Header.PointerToRelocations == 0 &&
|
|
"Section::PointerToRelocations is insane!");
|
|
return;
|
|
}
|
|
|
|
assert(W.OS.tell() == Sec.Header.PointerToRelocations &&
|
|
"Section::PointerToRelocations is insane!");
|
|
|
|
if (Sec.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 = Sec.Relocations.size() + 1;
|
|
R.SymbolTableIndex = 0;
|
|
R.Type = 0;
|
|
WriteRelocation(R);
|
|
}
|
|
|
|
for (const auto &Relocation : Sec.Relocations)
|
|
WriteRelocation(Relocation.Data);
|
|
}
|
|
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
// MCObjectWriter interface implementations
|
|
|
|
void WinCOFFObjectWriter::executePostLayoutBinding(MCAssembler &Asm,
|
|
const MCAsmLayout &Layout) {
|
|
if (EmitAddrsigSection) {
|
|
AddrsigSection = Asm.getContext().getCOFFSection(
|
|
".llvm_addrsig", COFF::IMAGE_SCN_LNK_REMOVE,
|
|
SectionKind::getMetadata());
|
|
Asm.registerSection(*AddrsigSection);
|
|
}
|
|
|
|
// "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 {
|
|
// Don't drop relocations between functions, even if they are in the same text
|
|
// section. Multiple Visual C++ linker features depend on having the
|
|
// relocations present. The /INCREMENTAL flag will cause these relocations to
|
|
// point to thunks, and the /GUARD:CF flag assumes that it can use relocations
|
|
// to approximate the set of all address taken functions. LLD's implementation
|
|
// of /GUARD:CF also relies on the existance of these relocations.
|
|
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);
|
|
}
|
|
|
|
void WinCOFFObjectWriter::recordRelocation(MCAssembler &Asm,
|
|
const MCAsmLayout &Layout,
|
|
const MCFragment *Fragment,
|
|
const MCFixup &Fixup, MCValue Target,
|
|
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 *MCSec = Fragment->getParent();
|
|
|
|
// Mark this symbol as requiring an entry in the symbol table.
|
|
assert(SectionMap.find(MCSec) != SectionMap.end() &&
|
|
"Section must already have been defined in executePostLayoutBinding!");
|
|
|
|
COFFSection *Sec = SectionMap[MCSec];
|
|
const MCSymbolRefExpr *SymB = Target.getSymB();
|
|
|
|
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;
|
|
}
|
|
|
|
// Offset of the symbol in the section
|
|
int64_t OffsetOfB = Layout.getSymbolOffset(*B);
|
|
|
|
// 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()) {
|
|
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(
|
|
Asm.getContext(), Target, Fixup, SymB, 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;
|
|
}
|
|
}
|
|
|
|
// The fixed value never makes sense for section indices, ignore it.
|
|
if (Fixup.getKind() == FK_SecRel_2)
|
|
FixedValue = 0;
|
|
|
|
if (TargetObjectWriter->recordRelocation(Fixup))
|
|
Sec->Relocations.push_back(Reloc);
|
|
}
|
|
|
|
static std::time_t getTime() {
|
|
std::time_t Now = time(nullptr);
|
|
if (Now < 0 || !isUInt<32>(Now))
|
|
return UINT32_MAX;
|
|
return Now;
|
|
}
|
|
|
|
// Create .file symbols.
|
|
void WinCOFFObjectWriter::createFileSymbols(MCAssembler &Asm) {
|
|
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;
|
|
}
|
|
}
|
|
}
|
|
|
|
static bool isAssociative(const COFFSection &Section) {
|
|
return Section.Symbol->Aux[0].Aux.SectionDefinition.Selection ==
|
|
COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE;
|
|
}
|
|
|
|
void WinCOFFObjectWriter::assignSectionNumbers() {
|
|
size_t I = 1;
|
|
auto Assign = [&](COFFSection &Section) {
|
|
Section.Number = I;
|
|
Section.Symbol->Data.SectionNumber = I;
|
|
Section.Symbol->Aux[0].Aux.SectionDefinition.Number = I;
|
|
++I;
|
|
};
|
|
|
|
// Although it is not explicitly requested by the Microsoft COFF spec,
|
|
// we should avoid emitting forward associative section references,
|
|
// because MSVC link.exe as of 2017 cannot handle that.
|
|
for (const std::unique_ptr<COFFSection> &Section : Sections)
|
|
if (!isAssociative(*Section))
|
|
Assign(*Section);
|
|
for (const std::unique_ptr<COFFSection> &Section : Sections)
|
|
if (isAssociative(*Section))
|
|
Assign(*Section);
|
|
}
|
|
|
|
// Assign file offsets to COFF object file structures.
|
|
void WinCOFFObjectWriter::assignFileOffsets(MCAssembler &Asm,
|
|
const MCAsmLayout &Layout) {
|
|
unsigned Offset = W.OS.tell();
|
|
|
|
Offset += UseBigObj ? COFF::Header32Size : 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)) {
|
|
Sec->Header.PointerToRawData = Offset;
|
|
Offset += Sec->Header.SizeOfRawData;
|
|
}
|
|
|
|
if (!Sec->Relocations.empty()) {
|
|
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;
|
|
}
|
|
|
|
uint64_t WinCOFFObjectWriter::writeObject(MCAssembler &Asm,
|
|
const MCAsmLayout &Layout) {
|
|
uint64_t StartOffset = W.OS.tell();
|
|
|
|
if (Sections.size() > INT32_MAX)
|
|
report_fatal_error(
|
|
"PE COFF object files can't have more than 2147483647 sections");
|
|
|
|
UseBigObj = Sections.size() > COFF::MaxNumberOfSections16;
|
|
Header.NumberOfSections = Sections.size();
|
|
Header.NumberOfSymbols = 0;
|
|
|
|
assignSectionNumbers();
|
|
createFileSymbols(Asm);
|
|
|
|
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 *AssocMCSym = MCSec.getCOMDATSymbol();
|
|
assert(AssocMCSym);
|
|
|
|
// It's an error to try to associate with an undefined symbol or a symbol
|
|
// without a section.
|
|
if (!AssocMCSym->isInSection()) {
|
|
Asm.getContext().reportError(
|
|
SMLoc(), Twine("cannot make section ") + MCSec.getSectionName() +
|
|
Twine(" associative with sectionless symbol ") +
|
|
AssocMCSym->getName());
|
|
continue;
|
|
}
|
|
|
|
const auto *AssocMCSec = cast<MCSectionCOFF>(&AssocMCSym->getSection());
|
|
assert(SectionMap.count(AssocMCSec));
|
|
COFFSection *AssocSec = SectionMap[AssocMCSec];
|
|
|
|
// Skip this section if the associated section is unused.
|
|
if (AssocSec->Number == -1)
|
|
continue;
|
|
|
|
Section->Symbol->Aux[0].Aux.SectionDefinition.Number = AssocSec->Number;
|
|
}
|
|
|
|
// Create the contents of the .llvm_addrsig section.
|
|
if (EmitAddrsigSection) {
|
|
auto Frag = new MCDataFragment(AddrsigSection);
|
|
Frag->setLayoutOrder(0);
|
|
raw_svector_ostream OS(Frag->getContents());
|
|
for (const MCSymbol *S : AddrsigSyms) {
|
|
if (!S->isTemporary()) {
|
|
encodeULEB128(S->getIndex(), OS);
|
|
continue;
|
|
}
|
|
|
|
MCSection *TargetSection = &S->getSection();
|
|
assert(SectionMap.find(TargetSection) != SectionMap.end() &&
|
|
"Section must already have been defined in "
|
|
"executePostLayoutBinding!");
|
|
encodeULEB128(SectionMap[TargetSection]->Symbol->getIndex(), OS);
|
|
}
|
|
}
|
|
|
|
assignFileOffsets(Asm, Layout);
|
|
|
|
// MS LINK expects to be able to use this timestamp to implement their
|
|
// /INCREMENTAL feature.
|
|
if (Asm.isIncrementalLinkerCompatible()) {
|
|
Header.TimeDateStamp = getTime();
|
|
} else {
|
|
// Have deterministic output if /INCREMENTAL isn't needed. Also matches GNU.
|
|
Header.TimeDateStamp = 0;
|
|
}
|
|
|
|
// Write it all to disk...
|
|
WriteFileHeader(Header);
|
|
writeSectionHeaders();
|
|
|
|
// Write section contents.
|
|
sections::iterator I = Sections.begin();
|
|
sections::iterator IE = Sections.end();
|
|
MCAssembler::iterator J = Asm.begin();
|
|
MCAssembler::iterator JE = Asm.end();
|
|
for (; I != IE && J != JE; ++I, ++J)
|
|
writeSection(Asm, Layout, **I, *J);
|
|
|
|
assert(W.OS.tell() == Header.PointerToSymbolTable &&
|
|
"Header::PointerToSymbolTable is insane!");
|
|
|
|
// Write a symbol table.
|
|
for (auto &Symbol : Symbols)
|
|
if (Symbol->getIndex() != -1)
|
|
WriteSymbol(*Symbol);
|
|
|
|
// Write a string table, which completes the entire COFF file.
|
|
Strings.write(W.OS);
|
|
|
|
return W.OS.tell() - StartOffset;
|
|
}
|
|
|
|
MCWinCOFFObjectTargetWriter::MCWinCOFFObjectTargetWriter(unsigned Machine_)
|
|
: Machine(Machine_) {}
|
|
|
|
// Pin the vtable to this file.
|
|
void MCWinCOFFObjectTargetWriter::anchor() {}
|
|
|
|
//------------------------------------------------------------------------------
|
|
// WinCOFFObjectWriter factory function
|
|
|
|
std::unique_ptr<MCObjectWriter> llvm::createWinCOFFObjectWriter(
|
|
std::unique_ptr<MCWinCOFFObjectTargetWriter> MOTW, raw_pwrite_stream &OS) {
|
|
return llvm::make_unique<WinCOFFObjectWriter>(std::move(MOTW), OS);
|
|
}
|