forked from OSchip/llvm-project
1142 lines
38 KiB
C++
1142 lines
38 KiB
C++
//===-- llvm/MC/WinCOFFObjectWriter.cpp -------------------------*- C++ -*-===//
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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/MC/MCWinCOFFObjectWriter.h"
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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/StringMap.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/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/MCObjectFileInfo.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/MCSymbolCOFF.h"
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#include "llvm/MC/MCValue.h"
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#include "llvm/MC/StringTableBuilder.h"
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#include "llvm/Support/COFF.h"
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#include "llvm/Support/Debug.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/TimeValue.h"
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#include <cstdio>
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#include <ctime>
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using namespace llvm;
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#define DEBUG_TYPE "WinCOFFObjectWriter"
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namespace {
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typedef SmallString<COFF::NameSize> name;
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enum AuxiliaryType {
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ATFunctionDefinition,
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ATbfAndefSymbol,
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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 COFFSymbol;
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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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typedef SmallVector<AuxSymbol, 1> AuxiliarySymbols;
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name Name;
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int Index;
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AuxiliarySymbols Aux;
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COFFSymbol *Other;
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COFFSection *Section;
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int Relocations;
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const MCSymbol *MC;
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COFFSymbol(StringRef name);
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void set_name_offset(uint32_t Offset);
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bool should_keep() const;
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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;
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COFFRelocation() : Symb(nullptr) {}
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static size_t size() { return COFF::RelocationSize; }
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};
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typedef std::vector<COFFRelocation> relocations;
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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;
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COFFSymbol *Symbol;
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relocations Relocations;
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COFFSection(StringRef name);
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static size_t size();
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};
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class WinCOFFObjectWriter : public MCObjectWriter {
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public:
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typedef std::vector<std::unique_ptr<COFFSymbol>> symbols;
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typedef std::vector<std::unique_ptr<COFFSection>> sections;
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typedef DenseMap<MCSymbol const *, COFFSymbol *> symbol_map;
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typedef DenseMap<MCSection const *, COFFSection *> section_map;
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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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WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW, 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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template <typename object_t, typename list_t>
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object_t *createCOFFEntity(StringRef Name, list_t &List);
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void defineSection(MCSectionCOFF const &Sec);
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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 ExportSymbol(const MCSymbol &Symbol, MCAssembler &Asm);
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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 writeSectionHeader(const COFF::section &S);
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void WriteRelocation(const COFF::relocation &R);
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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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bool isWeak(const MCSymbol &Sym) 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, bool &IsPCRel,
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uint64_t &FixedValue) override;
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void writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
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};
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}
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static inline void write_uint32_le(void *Data, uint32_t Value) {
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support::endian::write<uint32_t, support::little, support::unaligned>(Data,
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Value);
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}
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//------------------------------------------------------------------------------
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// Symbol class implementation
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COFFSymbol::COFFSymbol(StringRef name)
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: Name(name.begin(), name.end()), Other(nullptr), Section(nullptr),
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Relocations(0), MC(nullptr) {
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memset(&Data, 0, sizeof(Data));
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}
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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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write_uint32_le(Data.Name + 0, 0);
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write_uint32_le(Data.Name + 4, Offset);
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}
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/// logic to decide if the symbol should be reported in the symbol table
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bool COFFSymbol::should_keep() const {
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// no section means its external, keep it
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if (!Section)
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return true;
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// if it has relocations pointing at it, keep it
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if (Relocations > 0) {
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assert(Section->Number != -1 && "Sections with relocations must be real!");
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return true;
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}
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// if this is a safeseh handler, keep it
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if (MC && (cast<MCSymbolCOFF>(MC)->isSafeSEH()))
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return true;
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// if the section its in is being droped, drop it
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if (Section->Number == -1)
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return false;
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// if it is the section symbol, keep it
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if (Section->Symbol == this)
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return true;
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// if its temporary, drop it
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if (MC && MC->isTemporary())
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return false;
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// otherwise, keep it
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return true;
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}
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//------------------------------------------------------------------------------
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// Section class implementation
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COFFSection::COFFSection(StringRef name)
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: Name(name), MCSection(nullptr), Symbol(nullptr) {
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memset(&Header, 0, sizeof(Header));
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}
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size_t COFFSection::size() { return COFF::SectionSize; }
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//------------------------------------------------------------------------------
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// WinCOFFObjectWriter class implementation
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WinCOFFObjectWriter::WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW,
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raw_pwrite_stream &OS)
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: MCObjectWriter(OS, true), TargetObjectWriter(MOTW) {
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memset(&Header, 0, sizeof(Header));
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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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return createCOFFEntity<COFFSymbol>(Name, Symbols);
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}
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COFFSymbol *WinCOFFObjectWriter::GetOrCreateCOFFSymbol(const MCSymbol *Symbol) {
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symbol_map::iterator i = SymbolMap.find(Symbol);
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if (i != SymbolMap.end())
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return i->second;
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COFFSymbol *RetSymbol =
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createCOFFEntity<COFFSymbol>(Symbol->getName(), Symbols);
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SymbolMap[Symbol] = RetSymbol;
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return RetSymbol;
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}
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COFFSection *WinCOFFObjectWriter::createSection(StringRef Name) {
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return createCOFFEntity<COFFSection>(Name, Sections);
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}
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/// A template used to lookup or create a symbol/section, and initialize it if
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/// needed.
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template <typename object_t, typename list_t>
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object_t *WinCOFFObjectWriter::createCOFFEntity(StringRef Name, list_t &List) {
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List.push_back(make_unique<object_t>(Name));
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return List.back().get();
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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(MCSectionCOFF const &Sec) {
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COFFSection *coff_section = createSection(Sec.getSectionName());
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COFFSymbol *coff_symbol = createSymbol(Sec.getSectionName());
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if (Sec.getSelection() != COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
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if (const MCSymbol *S = Sec.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 = coff_section;
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}
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}
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coff_section->Symbol = coff_symbol;
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coff_symbol->Section = coff_section;
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coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_STATIC;
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// In this case the auxiliary symbol is a Section Definition.
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coff_symbol->Aux.resize(1);
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memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
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coff_symbol->Aux[0].AuxType = ATSectionDefinition;
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coff_symbol->Aux[0].Aux.SectionDefinition.Selection = Sec.getSelection();
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coff_section->Header.Characteristics = Sec.getCharacteristics();
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uint32_t &Characteristics = coff_section->Header.Characteristics;
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switch (Sec.getAlignment()) {
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case 1:
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Characteristics |= COFF::IMAGE_SCN_ALIGN_1BYTES;
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break;
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case 2:
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Characteristics |= COFF::IMAGE_SCN_ALIGN_2BYTES;
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break;
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case 4:
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Characteristics |= COFF::IMAGE_SCN_ALIGN_4BYTES;
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break;
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case 8:
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Characteristics |= COFF::IMAGE_SCN_ALIGN_8BYTES;
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break;
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case 16:
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Characteristics |= COFF::IMAGE_SCN_ALIGN_16BYTES;
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break;
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case 32:
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Characteristics |= COFF::IMAGE_SCN_ALIGN_32BYTES;
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break;
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case 64:
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Characteristics |= COFF::IMAGE_SCN_ALIGN_64BYTES;
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break;
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case 128:
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Characteristics |= COFF::IMAGE_SCN_ALIGN_128BYTES;
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break;
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case 256:
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Characteristics |= COFF::IMAGE_SCN_ALIGN_256BYTES;
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break;
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case 512:
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Characteristics |= COFF::IMAGE_SCN_ALIGN_512BYTES;
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break;
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case 1024:
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Characteristics |= COFF::IMAGE_SCN_ALIGN_1024BYTES;
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break;
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case 2048:
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Characteristics |= COFF::IMAGE_SCN_ALIGN_2048BYTES;
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break;
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case 4096:
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Characteristics |= COFF::IMAGE_SCN_ALIGN_4096BYTES;
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break;
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case 8192:
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Characteristics |= COFF::IMAGE_SCN_ALIGN_8192BYTES;
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break;
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default:
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llvm_unreachable("unsupported section alignment");
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}
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// Bind internal COFF section to MC section.
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coff_section->MCSection = &Sec;
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SectionMap[&Sec] = coff_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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/// 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 &Symbol,
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MCAssembler &Assembler,
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const MCAsmLayout &Layout) {
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COFFSymbol *coff_symbol = GetOrCreateCOFFSymbol(&Symbol);
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SymbolMap[&Symbol] = coff_symbol;
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if (cast<MCSymbolCOFF>(Symbol).isWeakExternal()) {
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coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
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if (Symbol.isVariable()) {
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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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report_fatal_error("Weak externals may only alias symbols");
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coff_symbol->Other = GetOrCreateCOFFSymbol(&SymRef->getSymbol());
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} else {
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std::string WeakName = (".weak." + Symbol.getName() + ".default").str();
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COFFSymbol *WeakDefault = createSymbol(WeakName);
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WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
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WeakDefault->Data.StorageClass = COFF::IMAGE_SYM_CLASS_EXTERNAL;
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WeakDefault->Data.Type = 0;
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WeakDefault->Data.Value = 0;
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coff_symbol->Other = WeakDefault;
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}
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// Setup the Weak External auxiliary symbol.
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coff_symbol->Aux.resize(1);
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memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
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coff_symbol->Aux[0].AuxType = ATWeakExternal;
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coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = 0;
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coff_symbol->Aux[0].Aux.WeakExternal.Characteristics =
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COFF::IMAGE_WEAK_EXTERN_SEARCH_LIBRARY;
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coff_symbol->MC = &Symbol;
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} else {
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const MCSymbol *Base = Layout.getBaseSymbol(Symbol);
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coff_symbol->Data.Value = getSymbolValue(Symbol, Layout);
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const MCSymbolCOFF &SymbolCOFF = cast<MCSymbolCOFF>(Symbol);
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coff_symbol->Data.Type = SymbolCOFF.getType();
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coff_symbol->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 (coff_symbol->Data.StorageClass == COFF::IMAGE_SYM_CLASS_NULL) {
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bool IsExternal = Symbol.isExternal() ||
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(!Symbol.getFragment() && !Symbol.isVariable());
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coff_symbol->Data.StorageClass = IsExternal
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? COFF::IMAGE_SYM_CLASS_EXTERNAL
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: COFF::IMAGE_SYM_CLASS_STATIC;
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}
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if (!Base) {
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coff_symbol->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
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} else {
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if (Base->getFragment()) {
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COFFSection *Sec = SectionMap[Base->getFragment()->getParent()];
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if (coff_symbol->Section && coff_symbol->Section != Sec)
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report_fatal_error("conflicting sections for symbol");
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coff_symbol->Section = Sec;
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}
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}
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coff_symbol->MC = &Symbol;
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}
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}
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// Maximum offsets for different string table entry encodings.
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static const unsigned Max6DecimalOffset = 999999;
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static const unsigned Max7DecimalOffset = 9999999;
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static const 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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uint64_t StringTableEntry = Strings.getOffset(S.Name);
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if (StringTableEntry <= Max6DecimalOffset) {
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std::sprintf(S.Header.Name, "/%d", unsigned(StringTableEntry));
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} else if (StringTableEntry <= Max7DecimalOffset) {
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// With seven digits, we have to skip the terminating null. Because
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// sprintf always appends it, we use a larger temporary buffer.
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char buffer[9] = {};
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std::sprintf(buffer, "/%d", unsigned(StringTableEntry));
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std::memcpy(S.Header.Name, buffer, 8);
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} else 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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} else {
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report_fatal_error("COFF string table is greater than 64 GB.");
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}
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} else
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std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size());
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}
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|
|
|
void WinCOFFObjectWriter::SetSymbolName(COFFSymbol &S) {
|
|
if (S.Name.size() > COFF::NameSize)
|
|
S.set_name_offset(Strings.getOffset(S.Name));
|
|
else
|
|
std::memcpy(S.Data.Name, S.Name.c_str(), S.Name.size());
|
|
}
|
|
|
|
bool WinCOFFObjectWriter::ExportSymbol(const MCSymbol &Symbol,
|
|
MCAssembler &Asm) {
|
|
// This doesn't seem to be right. Strings referred to from the .data section
|
|
// need symbols so they can be linked to code in the .text section right?
|
|
|
|
// return Asm.isSymbolLinkerVisible(Symbol);
|
|
|
|
// Non-temporary labels should always be visible to the linker.
|
|
if (!Symbol.isTemporary())
|
|
return true;
|
|
|
|
// Temporary variable symbols are invisible.
|
|
if (Symbol.isVariable())
|
|
return false;
|
|
|
|
// Absolute temporary labels are never visible.
|
|
return !Symbol.isAbsolute();
|
|
}
|
|
|
|
bool WinCOFFObjectWriter::IsPhysicalSection(COFFSection *S) {
|
|
return (S->Header.Characteristics & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) ==
|
|
0;
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
// entity writing methods
|
|
|
|
void WinCOFFObjectWriter::WriteFileHeader(const COFF::header &Header) {
|
|
if (UseBigObj) {
|
|
writeLE16(COFF::IMAGE_FILE_MACHINE_UNKNOWN);
|
|
writeLE16(0xFFFF);
|
|
writeLE16(COFF::BigObjHeader::MinBigObjectVersion);
|
|
writeLE16(Header.Machine);
|
|
writeLE32(Header.TimeDateStamp);
|
|
writeBytes(StringRef(COFF::BigObjMagic, sizeof(COFF::BigObjMagic)));
|
|
writeLE32(0);
|
|
writeLE32(0);
|
|
writeLE32(0);
|
|
writeLE32(0);
|
|
writeLE32(Header.NumberOfSections);
|
|
writeLE32(Header.PointerToSymbolTable);
|
|
writeLE32(Header.NumberOfSymbols);
|
|
} else {
|
|
writeLE16(Header.Machine);
|
|
writeLE16(static_cast<int16_t>(Header.NumberOfSections));
|
|
writeLE32(Header.TimeDateStamp);
|
|
writeLE32(Header.PointerToSymbolTable);
|
|
writeLE32(Header.NumberOfSymbols);
|
|
writeLE16(Header.SizeOfOptionalHeader);
|
|
writeLE16(Header.Characteristics);
|
|
}
|
|
}
|
|
|
|
void WinCOFFObjectWriter::WriteSymbol(const COFFSymbol &S) {
|
|
writeBytes(StringRef(S.Data.Name, COFF::NameSize));
|
|
writeLE32(S.Data.Value);
|
|
if (UseBigObj)
|
|
writeLE32(S.Data.SectionNumber);
|
|
else
|
|
writeLE16(static_cast<int16_t>(S.Data.SectionNumber));
|
|
writeLE16(S.Data.Type);
|
|
write8(S.Data.StorageClass);
|
|
write8(S.Data.NumberOfAuxSymbols);
|
|
WriteAuxiliarySymbols(S.Aux);
|
|
}
|
|
|
|
void WinCOFFObjectWriter::WriteAuxiliarySymbols(
|
|
const COFFSymbol::AuxiliarySymbols &S) {
|
|
for (COFFSymbol::AuxiliarySymbols::const_iterator i = S.begin(), e = S.end();
|
|
i != e; ++i) {
|
|
switch (i->AuxType) {
|
|
case ATFunctionDefinition:
|
|
writeLE32(i->Aux.FunctionDefinition.TagIndex);
|
|
writeLE32(i->Aux.FunctionDefinition.TotalSize);
|
|
writeLE32(i->Aux.FunctionDefinition.PointerToLinenumber);
|
|
writeLE32(i->Aux.FunctionDefinition.PointerToNextFunction);
|
|
WriteZeros(sizeof(i->Aux.FunctionDefinition.unused));
|
|
if (UseBigObj)
|
|
WriteZeros(COFF::Symbol32Size - COFF::Symbol16Size);
|
|
break;
|
|
case ATbfAndefSymbol:
|
|
WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused1));
|
|
writeLE16(i->Aux.bfAndefSymbol.Linenumber);
|
|
WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused2));
|
|
writeLE32(i->Aux.bfAndefSymbol.PointerToNextFunction);
|
|
WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused3));
|
|
if (UseBigObj)
|
|
WriteZeros(COFF::Symbol32Size - COFF::Symbol16Size);
|
|
break;
|
|
case ATWeakExternal:
|
|
writeLE32(i->Aux.WeakExternal.TagIndex);
|
|
writeLE32(i->Aux.WeakExternal.Characteristics);
|
|
WriteZeros(sizeof(i->Aux.WeakExternal.unused));
|
|
if (UseBigObj)
|
|
WriteZeros(COFF::Symbol32Size - COFF::Symbol16Size);
|
|
break;
|
|
case ATFile:
|
|
writeBytes(
|
|
StringRef(reinterpret_cast<const char *>(&i->Aux),
|
|
UseBigObj ? COFF::Symbol32Size : COFF::Symbol16Size));
|
|
break;
|
|
case ATSectionDefinition:
|
|
writeLE32(i->Aux.SectionDefinition.Length);
|
|
writeLE16(i->Aux.SectionDefinition.NumberOfRelocations);
|
|
writeLE16(i->Aux.SectionDefinition.NumberOfLinenumbers);
|
|
writeLE32(i->Aux.SectionDefinition.CheckSum);
|
|
writeLE16(static_cast<int16_t>(i->Aux.SectionDefinition.Number));
|
|
write8(i->Aux.SectionDefinition.Selection);
|
|
WriteZeros(sizeof(i->Aux.SectionDefinition.unused));
|
|
writeLE16(static_cast<int16_t>(i->Aux.SectionDefinition.Number >> 16));
|
|
if (UseBigObj)
|
|
WriteZeros(COFF::Symbol32Size - COFF::Symbol16Size);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
void WinCOFFObjectWriter::writeSectionHeader(const COFF::section &S) {
|
|
writeBytes(StringRef(S.Name, COFF::NameSize));
|
|
|
|
writeLE32(S.VirtualSize);
|
|
writeLE32(S.VirtualAddress);
|
|
writeLE32(S.SizeOfRawData);
|
|
writeLE32(S.PointerToRawData);
|
|
writeLE32(S.PointerToRelocations);
|
|
writeLE32(S.PointerToLineNumbers);
|
|
writeLE16(S.NumberOfRelocations);
|
|
writeLE16(S.NumberOfLineNumbers);
|
|
writeLE32(S.Characteristics);
|
|
}
|
|
|
|
void WinCOFFObjectWriter::WriteRelocation(const COFF::relocation &R) {
|
|
writeLE32(R.VirtualAddress);
|
|
writeLE32(R.SymbolTableIndex);
|
|
writeLE16(R.Type);
|
|
}
|
|
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
// MCObjectWriter interface implementations
|
|
|
|
void WinCOFFObjectWriter::executePostLayoutBinding(MCAssembler &Asm,
|
|
const MCAsmLayout &Layout) {
|
|
// "Define" each section & symbol. This creates section & symbol
|
|
// entries in the staging area.
|
|
for (const auto &Section : Asm)
|
|
defineSection(static_cast<const MCSectionCOFF &>(Section));
|
|
|
|
for (const MCSymbol &Symbol : Asm.symbols())
|
|
if (ExportSymbol(Symbol, Asm))
|
|
DefineSymbol(Symbol, Asm, Layout);
|
|
}
|
|
|
|
bool WinCOFFObjectWriter::isSymbolRefDifferenceFullyResolvedImpl(
|
|
const MCAssembler &Asm, const MCSymbol &SymA, const MCFragment &FB,
|
|
bool InSet, bool IsPCRel) const {
|
|
// MS LINK expects to be able to replace all references to a function with a
|
|
// thunk to implement their /INCREMENTAL feature. Make sure we don't optimize
|
|
// away any relocations to functions.
|
|
uint16_t Type = cast<MCSymbolCOFF>(SymA).getType();
|
|
if ((Type >> COFF::SCT_COMPLEX_TYPE_SHIFT) == COFF::IMAGE_SYM_DTYPE_FUNCTION)
|
|
return false;
|
|
return MCObjectWriter::isSymbolRefDifferenceFullyResolvedImpl(Asm, SymA, FB,
|
|
InSet, IsPCRel);
|
|
}
|
|
|
|
bool WinCOFFObjectWriter::isWeak(const MCSymbol &Sym) const {
|
|
if (!Sym.isExternal())
|
|
return false;
|
|
|
|
if (!Sym.isInSection())
|
|
return false;
|
|
|
|
const auto &Sec = cast<MCSectionCOFF>(Sym.getSection());
|
|
if (!Sec.getCOMDATSymbol())
|
|
return false;
|
|
|
|
// It looks like for COFF it is invalid to replace a reference to a global
|
|
// in a comdat with a reference to a local.
|
|
// FIXME: Add a specification reference if available.
|
|
return true;
|
|
}
|
|
|
|
void WinCOFFObjectWriter::recordRelocation(
|
|
MCAssembler &Asm, const MCAsmLayout &Layout, const MCFragment *Fragment,
|
|
const MCFixup &Fixup, MCValue Target, bool &IsPCRel, uint64_t &FixedValue) {
|
|
assert(Target.getSymA() && "Relocation must reference a symbol!");
|
|
|
|
const MCSymbol &Symbol = Target.getSymA()->getSymbol();
|
|
const MCSymbol &A = Symbol;
|
|
if (!A.isRegistered())
|
|
Asm.getContext().reportFatalError(Fixup.getLoc(),
|
|
Twine("symbol '") + A.getName() +
|
|
"' can not be undefined");
|
|
if (A.isTemporary() && A.isUndefined()) {
|
|
Asm.getContext().reportFatalError(Fixup.getLoc(),
|
|
Twine("assembler label '") + A.getName() +
|
|
"' can not be undefined");
|
|
}
|
|
|
|
MCSection *Section = Fragment->getParent();
|
|
|
|
// Mark this symbol as requiring an entry in the symbol table.
|
|
assert(SectionMap.find(Section) != SectionMap.end() &&
|
|
"Section must already have been defined in executePostLayoutBinding!");
|
|
assert(SymbolMap.find(&A) != SymbolMap.end() &&
|
|
"Symbol must already have been defined in executePostLayoutBinding!");
|
|
|
|
COFFSection *coff_section = SectionMap[Section];
|
|
COFFSymbol *coff_symbol = SymbolMap[&A];
|
|
const MCSymbolRefExpr *SymB = Target.getSymB();
|
|
bool CrossSection = false;
|
|
|
|
if (SymB) {
|
|
const MCSymbol *B = &SymB->getSymbol();
|
|
if (!B->getFragment())
|
|
Asm.getContext().reportFatalError(
|
|
Fixup.getLoc(),
|
|
Twine("symbol '") + B->getName() +
|
|
"' can not be undefined in a subtraction expression");
|
|
|
|
if (!A.getFragment())
|
|
Asm.getContext().reportFatalError(
|
|
Fixup.getLoc(),
|
|
Twine("symbol '") + Symbol.getName() +
|
|
"' can not be undefined in a subtraction expression");
|
|
|
|
CrossSection = &Symbol.getSection() != &B->getSection();
|
|
|
|
// Offset of the symbol in the section
|
|
int64_t OffsetOfB = Layout.getSymbolOffset(*B);
|
|
|
|
// In the case where we have SymbA and SymB, we just need to store the delta
|
|
// between the two symbols. Update FixedValue to account for the delta, and
|
|
// skip recording the relocation.
|
|
if (!CrossSection) {
|
|
int64_t OffsetOfA = Layout.getSymbolOffset(A);
|
|
FixedValue = (OffsetOfA - OffsetOfB) + Target.getConstant();
|
|
return;
|
|
}
|
|
|
|
// Offset of the relocation in the section
|
|
int64_t OffsetOfRelocation =
|
|
Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
|
|
|
|
FixedValue = (OffsetOfRelocation - OffsetOfB) + Target.getConstant();
|
|
} else {
|
|
FixedValue = Target.getConstant();
|
|
}
|
|
|
|
COFFRelocation Reloc;
|
|
|
|
Reloc.Data.SymbolTableIndex = 0;
|
|
Reloc.Data.VirtualAddress = Layout.getFragmentOffset(Fragment);
|
|
|
|
// Turn relocations for temporary symbols into section relocations.
|
|
if (coff_symbol->MC->isTemporary() || CrossSection) {
|
|
Reloc.Symb = coff_symbol->Section->Symbol;
|
|
FixedValue += Layout.getFragmentOffset(coff_symbol->MC->getFragment()) +
|
|
coff_symbol->MC->getOffset();
|
|
} else
|
|
Reloc.Symb = coff_symbol;
|
|
|
|
++Reloc.Symb->Relocations;
|
|
|
|
Reloc.Data.VirtualAddress += Fixup.getOffset();
|
|
Reloc.Data.Type = TargetObjectWriter->getRelocType(
|
|
Target, Fixup, CrossSection, Asm.getBackend());
|
|
|
|
// FIXME: Can anyone explain what this does other than adjust for the size
|
|
// of the offset?
|
|
if ((Header.Machine == COFF::IMAGE_FILE_MACHINE_AMD64 &&
|
|
Reloc.Data.Type == COFF::IMAGE_REL_AMD64_REL32) ||
|
|
(Header.Machine == COFF::IMAGE_FILE_MACHINE_I386 &&
|
|
Reloc.Data.Type == COFF::IMAGE_REL_I386_REL32))
|
|
FixedValue += 4;
|
|
|
|
if (Header.Machine == COFF::IMAGE_FILE_MACHINE_ARMNT) {
|
|
switch (Reloc.Data.Type) {
|
|
case COFF::IMAGE_REL_ARM_ABSOLUTE:
|
|
case COFF::IMAGE_REL_ARM_ADDR32:
|
|
case COFF::IMAGE_REL_ARM_ADDR32NB:
|
|
case COFF::IMAGE_REL_ARM_TOKEN:
|
|
case COFF::IMAGE_REL_ARM_SECTION:
|
|
case COFF::IMAGE_REL_ARM_SECREL:
|
|
break;
|
|
case COFF::IMAGE_REL_ARM_BRANCH11:
|
|
case COFF::IMAGE_REL_ARM_BLX11:
|
|
// IMAGE_REL_ARM_BRANCH11 and IMAGE_REL_ARM_BLX11 are only used for
|
|
// pre-ARMv7, which implicitly rules it out of ARMNT (it would be valid
|
|
// for Windows CE).
|
|
case COFF::IMAGE_REL_ARM_BRANCH24:
|
|
case COFF::IMAGE_REL_ARM_BLX24:
|
|
case COFF::IMAGE_REL_ARM_MOV32A:
|
|
// IMAGE_REL_ARM_BRANCH24, IMAGE_REL_ARM_BLX24, IMAGE_REL_ARM_MOV32A are
|
|
// only used for ARM mode code, which is documented as being unsupported
|
|
// by Windows on ARM. Empirical proof indicates that masm is able to
|
|
// generate the relocations however the rest of the MSVC toolchain is
|
|
// unable to handle it.
|
|
llvm_unreachable("unsupported relocation");
|
|
break;
|
|
case COFF::IMAGE_REL_ARM_MOV32T:
|
|
break;
|
|
case COFF::IMAGE_REL_ARM_BRANCH20T:
|
|
case COFF::IMAGE_REL_ARM_BRANCH24T:
|
|
case COFF::IMAGE_REL_ARM_BLX23T:
|
|
// IMAGE_REL_BRANCH20T, IMAGE_REL_ARM_BRANCH24T, IMAGE_REL_ARM_BLX23T all
|
|
// perform a 4 byte adjustment to the relocation. Relative branches are
|
|
// offset by 4 on ARM, however, because there is no RELA relocations, all
|
|
// branches are offset by 4.
|
|
FixedValue = FixedValue + 4;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (TargetObjectWriter->recordRelocation(Fixup))
|
|
coff_section->Relocations.push_back(Reloc);
|
|
}
|
|
|
|
void WinCOFFObjectWriter::writeObject(MCAssembler &Asm,
|
|
const MCAsmLayout &Layout) {
|
|
size_t SectionsSize = Sections.size();
|
|
if (SectionsSize > static_cast<size_t>(INT32_MAX))
|
|
report_fatal_error(
|
|
"PE COFF object files can't have more than 2147483647 sections");
|
|
|
|
// Assign symbol and section indexes and offsets.
|
|
int32_t NumberOfSections = static_cast<int32_t>(SectionsSize);
|
|
|
|
UseBigObj = NumberOfSections > COFF::MaxNumberOfSections16;
|
|
|
|
// Assign section numbers.
|
|
size_t Number = 1;
|
|
for (const auto &Section : Sections) {
|
|
Section->Number = Number;
|
|
Section->Symbol->Data.SectionNumber = Number;
|
|
Section->Symbol->Aux[0].Aux.SectionDefinition.Number = Number;
|
|
++Number;
|
|
}
|
|
|
|
Header.NumberOfSections = NumberOfSections;
|
|
Header.NumberOfSymbols = 0;
|
|
|
|
for (const std::string &Name : Asm.getFileNames()) {
|
|
// round up to calculate the number of auxiliary symbols required
|
|
unsigned SymbolSize = UseBigObj ? COFF::Symbol32Size : COFF::Symbol16Size;
|
|
unsigned Count = (Name.size() + SymbolSize - 1) / SymbolSize;
|
|
|
|
COFFSymbol *file = createSymbol(".file");
|
|
file->Data.SectionNumber = COFF::IMAGE_SYM_DEBUG;
|
|
file->Data.StorageClass = COFF::IMAGE_SYM_CLASS_FILE;
|
|
file->Aux.resize(Count);
|
|
|
|
unsigned Offset = 0;
|
|
unsigned Length = Name.size();
|
|
for (auto &Aux : file->Aux) {
|
|
Aux.AuxType = ATFile;
|
|
|
|
if (Length > SymbolSize) {
|
|
memcpy(&Aux.Aux, Name.c_str() + Offset, SymbolSize);
|
|
Length = Length - SymbolSize;
|
|
} else {
|
|
memcpy(&Aux.Aux, Name.c_str() + Offset, Length);
|
|
memset((char *)&Aux.Aux + Length, 0, SymbolSize - Length);
|
|
break;
|
|
}
|
|
|
|
Offset += SymbolSize;
|
|
}
|
|
}
|
|
|
|
for (auto &Symbol : Symbols) {
|
|
// Update section number & offset for symbols that have them.
|
|
if (Symbol->Section)
|
|
Symbol->Data.SectionNumber = Symbol->Section->Number;
|
|
if (Symbol->should_keep()) {
|
|
Symbol->setIndex(Header.NumberOfSymbols++);
|
|
// Update auxiliary symbol info.
|
|
Symbol->Data.NumberOfAuxSymbols = Symbol->Aux.size();
|
|
Header.NumberOfSymbols += Symbol->Data.NumberOfAuxSymbols;
|
|
} else {
|
|
Symbol->setIndex(-1);
|
|
}
|
|
}
|
|
|
|
// Build string table.
|
|
for (const auto &S : Sections)
|
|
if (S->Name.size() > COFF::NameSize)
|
|
Strings.add(S->Name);
|
|
for (const auto &S : Symbols)
|
|
if (S->should_keep() && S->Name.size() > COFF::NameSize)
|
|
Strings.add(S->Name);
|
|
Strings.finalize();
|
|
|
|
// Set names.
|
|
for (const auto &S : Sections)
|
|
SetSectionName(*S);
|
|
for (auto &S : Symbols)
|
|
if (S->should_keep())
|
|
SetSymbolName(*S);
|
|
|
|
// Fixup weak external references.
|
|
for (auto &Symbol : Symbols) {
|
|
if (Symbol->Other) {
|
|
assert(Symbol->getIndex() != -1);
|
|
assert(Symbol->Aux.size() == 1 && "Symbol must contain one aux symbol!");
|
|
assert(Symbol->Aux[0].AuxType == ATWeakExternal &&
|
|
"Symbol's aux symbol must be a Weak External!");
|
|
Symbol->Aux[0].Aux.WeakExternal.TagIndex = Symbol->Other->getIndex();
|
|
}
|
|
}
|
|
|
|
// Fixup associative COMDAT sections.
|
|
for (auto &Section : Sections) {
|
|
if (Section->Symbol->Aux[0].Aux.SectionDefinition.Selection !=
|
|
COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE)
|
|
continue;
|
|
|
|
const MCSectionCOFF &MCSec = *Section->MCSection;
|
|
|
|
const MCSymbol *COMDAT = MCSec.getCOMDATSymbol();
|
|
assert(COMDAT);
|
|
COFFSymbol *COMDATSymbol = GetOrCreateCOFFSymbol(COMDAT);
|
|
assert(COMDATSymbol);
|
|
COFFSection *Assoc = COMDATSymbol->Section;
|
|
if (!Assoc)
|
|
report_fatal_error(
|
|
Twine("Missing associated COMDAT section for section ") +
|
|
MCSec.getSectionName());
|
|
|
|
// Skip this section if the associated section is unused.
|
|
if (Assoc->Number == -1)
|
|
continue;
|
|
|
|
Section->Symbol->Aux[0].Aux.SectionDefinition.Number = Assoc->Number;
|
|
}
|
|
|
|
// Assign file offsets to COFF object file structures.
|
|
|
|
unsigned offset = 0;
|
|
|
|
if (UseBigObj)
|
|
offset += COFF::Header32Size;
|
|
else
|
|
offset += COFF::Header16Size;
|
|
offset += COFF::SectionSize * Header.NumberOfSections;
|
|
|
|
for (const auto &Section : Asm) {
|
|
COFFSection *Sec = SectionMap[&Section];
|
|
|
|
if (Sec->Number == -1)
|
|
continue;
|
|
|
|
Sec->Header.SizeOfRawData = Layout.getSectionAddressSize(&Section);
|
|
|
|
if (IsPhysicalSection(Sec)) {
|
|
// Align the section data to a four byte boundary.
|
|
offset = RoundUpToAlignment(offset, 4);
|
|
Sec->Header.PointerToRawData = offset;
|
|
|
|
offset += Sec->Header.SizeOfRawData;
|
|
}
|
|
|
|
if (Sec->Relocations.size() > 0) {
|
|
bool RelocationsOverflow = Sec->Relocations.size() >= 0xffff;
|
|
|
|
if (RelocationsOverflow) {
|
|
// Signal overflow by setting NumberOfRelocations to max value. Actual
|
|
// size is found in reloc #0. Microsoft tools understand this.
|
|
Sec->Header.NumberOfRelocations = 0xffff;
|
|
} else {
|
|
Sec->Header.NumberOfRelocations = Sec->Relocations.size();
|
|
}
|
|
Sec->Header.PointerToRelocations = offset;
|
|
|
|
if (RelocationsOverflow) {
|
|
// Reloc #0 will contain actual count, so make room for it.
|
|
offset += COFF::RelocationSize;
|
|
}
|
|
|
|
offset += COFF::RelocationSize * Sec->Relocations.size();
|
|
|
|
for (auto &Relocation : Sec->Relocations) {
|
|
assert(Relocation.Symb->getIndex() != -1);
|
|
Relocation.Data.SymbolTableIndex = Relocation.Symb->getIndex();
|
|
}
|
|
}
|
|
|
|
assert(Sec->Symbol->Aux.size() == 1 &&
|
|
"Section's symbol must have one aux!");
|
|
AuxSymbol &Aux = Sec->Symbol->Aux[0];
|
|
assert(Aux.AuxType == ATSectionDefinition &&
|
|
"Section's symbol's aux symbol must be a Section Definition!");
|
|
Aux.Aux.SectionDefinition.Length = Sec->Header.SizeOfRawData;
|
|
Aux.Aux.SectionDefinition.NumberOfRelocations =
|
|
Sec->Header.NumberOfRelocations;
|
|
Aux.Aux.SectionDefinition.NumberOfLinenumbers =
|
|
Sec->Header.NumberOfLineNumbers;
|
|
}
|
|
|
|
Header.PointerToSymbolTable = offset;
|
|
|
|
#if (ENABLE_TIMESTAMPS == 1)
|
|
// MS LINK expects to be able to use this timestamp to implement their
|
|
// /INCREMENTAL feature.
|
|
std::time_t Now = time(nullptr);
|
|
if (Now < 0 || !isUInt<32>(Now))
|
|
Now = UINT32_MAX;
|
|
Header.TimeDateStamp = Now;
|
|
#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);
|
|
}
|