path: root/lib/MC/ELFObjectWriter.cpp

//===- lib/MC/ELFObjectWriter.cpp - ELF File Writer -------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements ELF object file writer information.
//
//===----------------------------------------------------------------------===//

#include "llvm/MC/ELFObjectWriter.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/Twine.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCAsmLayout.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCELFSymbolFlags.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCValue.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/ELF.h"
#include "llvm/Target/TargetAsmBackend.h"

#include "../Target/X86/X86FixupKinds.h"

#include <vector>
using namespace llvm;

namespace {

  class ELFObjectWriterImpl {
    static bool isFixupKindX86PCRel(unsigned Kind) {
      switch (Kind) {
      default:
        return false;
      case X86::reloc_pcrel_1byte:
      case X86::reloc_pcrel_4byte:
      case X86::reloc_riprel_4byte:
      case X86::reloc_riprel_4byte_movq_load:
        return true;
      }
    }

    /*static bool isFixupKindX86RIPRel(unsigned Kind) {
      return Kind == X86::reloc_riprel_4byte ||
        Kind == X86::reloc_riprel_4byte_movq_load;
    }*/


    /// ELFSymbolData - Helper struct for containing some precomputed information
    /// on symbols.
    struct ELFSymbolData {
      MCSymbolData *SymbolData;
      uint64_t StringIndex;
      uint32_t SectionIndex;

      // Support lexicographic sorting.
      bool operator<(const ELFSymbolData &RHS) const {
        return SymbolData->getSymbol().getName() <
               RHS.SymbolData->getSymbol().getName();
      }
    };

    /// @name Relocation Data
    /// @{

    struct ELFRelocationEntry {
      // Make these big enough for both 32-bit and 64-bit
      uint64_t r_offset;
      uint64_t r_info;
      uint64_t r_addend;

      // Support lexicographic sorting.
      bool operator<(const ELFRelocationEntry &RE) const {
        return RE.r_offset < r_offset;
      }
    };

    llvm::DenseMap<const MCSectionData*,
                   std::vector<ELFRelocationEntry> > Relocations;
    DenseMap<const MCSection*, uint64_t> SectionStringTableIndex;

    /// @}
    /// @name Symbol Table Data
    /// @{

    SmallString<256> StringTable;
    std::vector<ELFSymbolData> LocalSymbolData;
    std::vector<ELFSymbolData> ExternalSymbolData;
    std::vector<ELFSymbolData> UndefinedSymbolData;

    /// @}

    ELFObjectWriter *Writer;

    raw_ostream &OS;

    // This holds the current offset into the object file.
    size_t FileOff;

    unsigned Is64Bit : 1;

    bool HasRelocationAddend;

    // This holds the symbol table index of the last local symbol.
    unsigned LastLocalSymbolIndex;
    // This holds the .strtab section index.
    unsigned StringTableIndex;

    unsigned ShstrtabIndex;

  public:
    ELFObjectWriterImpl(ELFObjectWriter *_Writer, bool _Is64Bit,
                        bool _HasRelAddend)
      : Writer(_Writer), OS(Writer->getStream()), FileOff(0),
        Is64Bit(_Is64Bit), HasRelocationAddend(_HasRelAddend) {
    }

    void Write8(uint8_t Value) { Writer->Write8(Value); }
    void Write16(uint16_t Value) { Writer->Write16(Value); }
    void Write32(uint32_t Value) { Writer->Write32(Value); }
    //void Write64(uint64_t Value) { Writer->Write64(Value); }
    void WriteZeros(unsigned N) { Writer->WriteZeros(N); }
    //void WriteBytes(StringRef Str, unsigned ZeroFillSize = 0) {
    //  Writer->WriteBytes(Str, ZeroFillSize);
    //}

    void WriteWord(uint64_t W) {
      if (Is64Bit)
        Writer->Write64(W);
      else
        Writer->Write32(W);
    }

    void String8(char *buf, uint8_t Value) {
      buf[0] = Value;
    }

    void StringLE16(char *buf, uint16_t Value) {
      buf[0] = char(Value >> 0);
      buf[1] = char(Value >> 8);
    }

    void StringLE32(char *buf, uint32_t Value) {
      StringLE16(buf, uint16_t(Value >> 0));
      StringLE16(buf + 2, uint16_t(Value >> 16));
    }

    void StringLE64(char *buf, uint64_t Value) {
      StringLE32(buf, uint32_t(Value >> 0));
      StringLE32(buf