void ELFObjectWriter::writeSectionHeader(
    const MCAsmLayout &Layout, const SectionIndexMapTy &SectionIndexMap,
    const SectionOffsetsTy &SectionOffsets) {
  const unsigned NumSections = SectionTable.size();

  // Null section first.
  uint64_t FirstSectionSize =
      (NumSections + 1) >= ELF::SHN_LORESERVE ? NumSections + 1 : 0;
  WriteSecHdrEntry(0, 0, 0, 0, 0, FirstSectionSize, 0, 0, 0, 0);

  for (const MCSectionELF *Section : SectionTable) {
    uint32_t GroupSymbolIndex;
    unsigned Type = Section->getType();
    if (Type != ELF::SHT_GROUP)
      GroupSymbolIndex = 0;
    else
      GroupSymbolIndex = Section->getGroup()->getIndex();

    const std::pair<uint64_t, uint64_t> &Offsets =
        SectionOffsets.find(Section)->second;
    uint64_t Size;
    if (Type == ELF::SHT_NOBITS)
      Size = Layout.getSectionAddressSize(Section);
    else
      Size = Offsets.second - Offsets.first;

    writeSection(SectionIndexMap, GroupSymbolIndex, Offsets.first, Size,
                 *Section);
  }
}
uint32_t SVMMemoryLayout::getSectionMemSize(const MCSectionData *SD, const MCAsmLayout &Layout) const
{
    SectionMemSizeOverrides_t::const_iterator it = SectionMemSizeOverrides.find(SD);
    if (it == SectionMemSizeOverrides.end())
        return Layout.getSectionAddressSize(SD);
    else
        return it->second;
}
Exemple #3
0
uint64_t MCCodePaddingPolicy::getNextFragmentOffset(const MCFragment *Fragment,
                                                    const MCAsmLayout &Layout) {
  assert(Fragment != nullptr && "Fragment cannot be null");
  MCFragment const *NextFragment = Fragment->getNextNode();
  return NextFragment == nullptr
             ? Layout.getSectionAddressSize(Fragment->getParent())
             : Layout.getFragmentOffset(NextFragment);
}
Exemple #4
0
void MCAssembler::writeSectionData(const MCSectionData *SD,
                                   const MCAsmLayout &Layout) const {
  // Ignore virtual sections.
  if (SD->getSection().isVirtualSection()) {
    assert(Layout.getSectionFileSize(SD) == 0 && "Invalid size for section!");

    // Check that contents are only things legal inside a virtual section.
    for (MCSectionData::const_iterator it = SD->begin(),
           ie = SD->end(); it != ie; ++it) {
      switch (it->getKind()) {
      default: llvm_unreachable("Invalid fragment in virtual section!");
      case MCFragment::FT_Data: {
        // Check that we aren't trying to write a non-zero contents (or fixups)
        // into a virtual section. This is to support clients which use standard
        // directives to fill the contents of virtual sections.
        const MCDataFragment &DF = cast<MCDataFragment>(*it);
        assert(DF.fixup_begin() == DF.fixup_end() &&
               "Cannot have fixups in virtual section!");
        for (unsigned i = 0, e = DF.getContents().size(); i != e; ++i)
          if (DF.getContents()[i]) {
            if (auto *ELFSec = dyn_cast<const MCSectionELF>(&SD->getSection()))
              report_fatal_error("non-zero initializer found in section '" +
                  ELFSec->getSectionName() + "'");
            else
              report_fatal_error("non-zero initializer found in virtual section");
          }
        break;
      }
      case MCFragment::FT_Align:
        // Check that we aren't trying to write a non-zero value into a virtual
        // section.
        assert((cast<MCAlignFragment>(it)->getValueSize() == 0 ||
                cast<MCAlignFragment>(it)->getValue() == 0) &&
               "Invalid align in virtual section!");
        break;
      case MCFragment::FT_Fill:
        assert((cast<MCFillFragment>(it)->getValueSize() == 0 ||
                cast<MCFillFragment>(it)->getValue() == 0) &&
               "Invalid fill in virtual section!");
        break;
      }
    }

    return;
  }

  uint64_t Start = getWriter().getStream().tell();
  (void)Start;

  for (MCSectionData::const_iterator it = SD->begin(), ie = SD->end();
       it != ie; ++it)
    writeFragment(*this, Layout, *it);

  assert(getWriter().getStream().tell() - Start ==
         Layout.getSectionAddressSize(SD));
}
Exemple #5
0
uint64_t MachObjectWriter::getPaddingSize(const MCSection *Sec,
                                          const MCAsmLayout &Layout) const {
  uint64_t EndAddr = getSectionAddress(Sec) + Layout.getSectionAddressSize(Sec);
  unsigned Next = Sec->getLayoutOrder() + 1;
  if (Next >= Layout.getSectionOrder().size())
    return 0;

  const MCSection &NextSec = *Layout.getSectionOrder()[Next];
  if (NextSec.isVirtualSection())
    return 0;
  return OffsetToAlignment(EndAddr, NextSec.getAlignment());
}
Exemple #6
0
void MachObjectWriter::computeSectionAddresses(const MCAssembler &Asm,
                                               const MCAsmLayout &Layout) {
  uint64_t StartAddress = 0;
  for (const MCSection *Sec : Layout.getSectionOrder()) {
    StartAddress = alignTo(StartAddress, Sec->getAlignment());
    SectionAddress[Sec] = StartAddress;
    StartAddress += Layout.getSectionAddressSize(Sec);

    // Explicitly pad the section to match the alignment requirements of the
    // following one. This is for 'gas' compatibility, it shouldn't
    /// strictly be necessary.
    StartAddress += getPaddingSize(Sec, Layout);
  }
}
Exemple #7
0
void MachObjectWriter::WriteSection(const MCAssembler &Asm,
                                    const MCAsmLayout &Layout,
                                    const MCSectionData &SD,
                                    uint64_t FileOffset,
                                    uint64_t RelocationsStart,
                                    unsigned NumRelocations) {
  uint64_t SectionSize = Layout.getSectionAddressSize(&SD);

  // The offset is unused for virtual sections.
  if (SD.getSection().isVirtualSection()) {
    assert(Layout.getSectionFileSize(&SD) == 0 && "Invalid file size!");
    FileOffset = 0;
  }

  // struct section (68 bytes) or
  // struct section_64 (80 bytes)

  uint64_t Start = OS.tell();
  (void) Start;

  const MCSectionMachO &Section = cast<MCSectionMachO>(SD.getSection());
  WriteBytes(Section.getSectionName(), 16);
  WriteBytes(Section.getSegmentName(), 16);
  if (is64Bit()) {
    Write64(getSectionAddress(&SD)); // address
    Write64(SectionSize); // size
  } else {
    Write32(getSectionAddress(&SD)); // address
    Write32(SectionSize); // size
  }
  Write32(FileOffset);

  unsigned Flags = Section.getTypeAndAttributes();
  if (SD.hasInstructions())
    Flags |= MCSectionMachO::S_ATTR_SOME_INSTRUCTIONS;

  assert(isPowerOf2_32(SD.getAlignment()) && "Invalid alignment!");
  Write32(Log2_32(SD.getAlignment()));
  Write32(NumRelocations ? RelocationsStart : 0);
  Write32(NumRelocations);
  Write32(Flags);
  Write32(IndirectSymBase.lookup(&SD)); // reserved1
  Write32(Section.getStubSize()); // reserved2
  if (is64Bit())
    Write32(0); // reserved3

  assert(OS.tell() - Start == (is64Bit() ? macho::Section64Size :
                               macho::Section32Size));
}
Exemple #8
0
void MachObjectWriter::computeSectionAddresses(const MCAssembler &Asm,
                                               const MCAsmLayout &Layout) {
  uint64_t StartAddress = 0;
  const SmallVectorImpl<MCSectionData*> &Order = Layout.getSectionOrder();
  for (int i = 0, n = Order.size(); i != n ; ++i) {
    const MCSectionData *SD = Order[i];
    StartAddress = RoundUpToAlignment(StartAddress, SD->getAlignment());
    SectionAddress[SD] = StartAddress;
    StartAddress += Layout.getSectionAddressSize(SD);

    // Explicitly pad the section to match the alignment requirements of the
    // following one. This is for 'gas' compatibility, it shouldn't
    /// strictly be necessary.
    StartAddress += getPaddingSize(SD, Layout);
  }
}
void SVMMemoryLayout::AllocateSections(MCAssembler &Asm, const MCAsmLayout &Layout)
{
    memset(spsMemSize, 0, sizeof spsMemSize);
    memset(spsDiskSize, 0, sizeof spsDiskSize);
    bssAlign = 1;

    // Leave one free block at the beginning of DEBUG, for a special message.
    spsMemSize[SPS_DEBUG] = SVMTargetMachine::getBlockSize();
    spsDiskSize[SPS_DEBUG] = spsMemSize[SPS_DEBUG];

    for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
        it != ie; ++it) {
        const MCSectionData *SD = &*it;
        SVMProgramSection sps = getSectionKind(SD);

        switch (sps) {

        case SPS_BSS:
            // Also track BSS segment alignment, then fall through...
            bssAlign = std::max(bssAlign, SD->getAlignment());

        case SPS_RO:
        case SPS_RW_Z:
        case SPS_RW_PLAIN:
        case SPS_DEBUG:
        case SPS_META:
            spsMemSize[sps] = RoundUpToAlignment(spsMemSize[sps], SD->getAlignment());
            spsDiskSize[sps] = RoundUpToAlignment(spsDiskSize[sps], SD->getAlignment());

            SectionOffsetMap[SD] = spsDiskSize[sps];

            spsMemSize[sps] += getSectionMemSize(SD, Layout);
            spsDiskSize[sps] += Layout.getSectionAddressSize(SD);
            break;

        default:
            break;
        }
    }

    unsigned memUsed = getSectionMemAddress(SPS_END) - SVMTargetMachine::getRAMBase();
    unsigned memMax = SVMTargetMachine::getRAMSize();
    if (memUsed > memMax)
        report_fatal_error("Application is too large to fit in RAM! Need "
            + Twine(memUsed) + " bytes, which exceeds the maximum of " + Twine(memMax));
}
Exemple #10
0
void MachObjectWriter::writeSection(const MCAsmLayout &Layout,
                                    const MCSection &Sec, uint64_t VMAddr,
                                    uint64_t FileOffset, unsigned Flags,
                                    uint64_t RelocationsStart,
                                    unsigned NumRelocations) {
  uint64_t SectionSize = Layout.getSectionAddressSize(&Sec);
  const MCSectionMachO &Section = cast<MCSectionMachO>(Sec);

  // The offset is unused for virtual sections.
  if (Section.isVirtualSection()) {
    assert(Layout.getSectionFileSize(&Sec) == 0 && "Invalid file size!");
    FileOffset = 0;
  }

  // struct section (68 bytes) or
  // struct section_64 (80 bytes)

  uint64_t Start = getStream().tell();
  (void) Start;

  writeBytes(Section.getSectionName(), 16);
  writeBytes(Section.getSegmentName(), 16);
  if (is64Bit()) {
    write64(VMAddr);      // address
    write64(SectionSize); // size
  } else {
    write32(VMAddr);      // address
    write32(SectionSize); // size
  }
  write32(FileOffset);

  assert(isPowerOf2_32(Section.getAlignment()) && "Invalid alignment!");
  write32(Log2_32(Section.getAlignment()));
  write32(NumRelocations ? RelocationsStart : 0);
  write32(NumRelocations);
  write32(Flags);
  write32(IndirectSymBase.lookup(&Sec)); // reserved1
  write32(Section.getStubSize()); // reserved2
  if (is64Bit())
    write32(0); // reserved3

  assert(getStream().tell() - Start ==
         (is64Bit() ? sizeof(MachO::section_64) : sizeof(MachO::section)));
}
Exemple #11
0
void MachObjectWriter::writeObject(MCAssembler &Asm,
                                   const MCAsmLayout &Layout) {
  // Compute symbol table information and bind symbol indices.
  computeSymbolTable(Asm, LocalSymbolData, ExternalSymbolData,
                     UndefinedSymbolData);

  unsigned NumSections = Asm.size();
  const MCAssembler::VersionMinInfoType &VersionInfo =
    Layout.getAssembler().getVersionMinInfo();

  // The section data starts after the header, the segment load command (and
  // section headers) and the symbol table.
  unsigned NumLoadCommands = 1;
  uint64_t LoadCommandsSize = is64Bit() ?
    sizeof(MachO::segment_command_64) + NumSections * sizeof(MachO::section_64):
    sizeof(MachO::segment_command) + NumSections * sizeof(MachO::section);

  // Add the deployment target version info load command size, if used.
  if (VersionInfo.Major != 0) {
    ++NumLoadCommands;
    LoadCommandsSize += sizeof(MachO::version_min_command);
  }

  // Add the data-in-code load command size, if used.
  unsigned NumDataRegions = Asm.getDataRegions().size();
  if (NumDataRegions) {
    ++NumLoadCommands;
    LoadCommandsSize += sizeof(MachO::linkedit_data_command);
  }

  // Add the loh load command size, if used.
  uint64_t LOHRawSize = Asm.getLOHContainer().getEmitSize(*this, Layout);
  uint64_t LOHSize = alignTo(LOHRawSize, is64Bit() ? 8 : 4);
  if (LOHSize) {
    ++NumLoadCommands;
    LoadCommandsSize += sizeof(MachO::linkedit_data_command);
  }

  // Add the symbol table load command sizes, if used.
  unsigned NumSymbols = LocalSymbolData.size() + ExternalSymbolData.size() +
    UndefinedSymbolData.size();
  if (NumSymbols) {
    NumLoadCommands += 2;
    LoadCommandsSize += (sizeof(MachO::symtab_command) +
                         sizeof(MachO::dysymtab_command));
  }

  // Add the linker option load commands sizes.
  for (const auto &Option : Asm.getLinkerOptions()) {
    ++NumLoadCommands;
    LoadCommandsSize += ComputeLinkerOptionsLoadCommandSize(Option, is64Bit());
  }

  // Compute the total size of the section data, as well as its file size and vm
  // size.
  uint64_t SectionDataStart = (is64Bit() ? sizeof(MachO::mach_header_64) :
                               sizeof(MachO::mach_header)) + LoadCommandsSize;
  uint64_t SectionDataSize = 0;
  uint64_t SectionDataFileSize = 0;
  uint64_t VMSize = 0;
  for (const MCSection &Sec : Asm) {
    uint64_t Address = getSectionAddress(&Sec);
    uint64_t Size = Layout.getSectionAddressSize(&Sec);
    uint64_t FileSize = Layout.getSectionFileSize(&Sec);
    FileSize += getPaddingSize(&Sec, Layout);

    VMSize = std::max(VMSize, Address + Size);

    if (Sec.isVirtualSection())
      continue;

    SectionDataSize = std::max(SectionDataSize, Address + Size);
    SectionDataFileSize = std::max(SectionDataFileSize, Address + FileSize);
  }

  // The section data is padded to 4 bytes.
  //
  // FIXME: Is this machine dependent?
  unsigned SectionDataPadding = OffsetToAlignment(SectionDataFileSize, 4);
  SectionDataFileSize += SectionDataPadding;

  // Write the prolog, starting with the header and load command...
  writeHeader(MachO::MH_OBJECT, NumLoadCommands, LoadCommandsSize,
              Asm.getSubsectionsViaSymbols());
  uint32_t Prot =
      MachO::VM_PROT_READ | MachO::VM_PROT_WRITE | MachO::VM_PROT_EXECUTE;
  writeSegmentLoadCommand("", NumSections, 0, VMSize, SectionDataStart,
                          SectionDataSize, Prot, Prot);

  // ... and then the section headers.
  uint64_t RelocTableEnd = SectionDataStart + SectionDataFileSize;
  for (const MCSection &Section : Asm) {
    const auto &Sec = cast<MCSectionMachO>(Section);
    std::vector<RelAndSymbol> &Relocs = Relocations[&Sec];
    unsigned NumRelocs = Relocs.size();
    uint64_t SectionStart = SectionDataStart + getSectionAddress(&Sec);
    unsigned Flags = Sec.getTypeAndAttributes();
    if (Sec.hasInstructions())
      Flags |= MachO::S_ATTR_SOME_INSTRUCTIONS;
    writeSection(Layout, Sec, getSectionAddress(&Sec), SectionStart, Flags,
                 RelocTableEnd, NumRelocs);
    RelocTableEnd += NumRelocs * sizeof(MachO::any_relocation_info);
  }

  // Write out the deployment target information, if it's available.
  if (VersionInfo.Major != 0) {
    assert(VersionInfo.Update < 256 && "unencodable update target version");
    assert(VersionInfo.Minor < 256 && "unencodable minor target version");
    assert(VersionInfo.Major < 65536 && "unencodable major target version");
    uint32_t EncodedVersion = VersionInfo.Update | (VersionInfo.Minor << 8) |
      (VersionInfo.Major << 16);
    MachO::LoadCommandType LCType;
    switch (VersionInfo.Kind) {
    case MCVM_OSXVersionMin:
      LCType = MachO::LC_VERSION_MIN_MACOSX;
      break;
    case MCVM_IOSVersionMin:
      LCType = MachO::LC_VERSION_MIN_IPHONEOS;
      break;
    case MCVM_TvOSVersionMin:
      LCType = MachO::LC_VERSION_MIN_TVOS;
      break;
    case MCVM_WatchOSVersionMin:
      LCType = MachO::LC_VERSION_MIN_WATCHOS;
      break;
    }
    write32(LCType);
    write32(sizeof(MachO::version_min_command));
    write32(EncodedVersion);
    write32(0);         // reserved.
  }

  // Write the data-in-code load command, if used.
  uint64_t DataInCodeTableEnd = RelocTableEnd + NumDataRegions * 8;
  if (NumDataRegions) {
    uint64_t DataRegionsOffset = RelocTableEnd;
    uint64_t DataRegionsSize = NumDataRegions * 8;
    writeLinkeditLoadCommand(MachO::LC_DATA_IN_CODE, DataRegionsOffset,
                             DataRegionsSize);
  }

  // Write the loh load command, if used.
  uint64_t LOHTableEnd = DataInCodeTableEnd + LOHSize;
  if (LOHSize)
    writeLinkeditLoadCommand(MachO::LC_LINKER_OPTIMIZATION_HINT,
                             DataInCodeTableEnd, LOHSize);

  // Write the symbol table load command, if used.
  if (NumSymbols) {
    unsigned FirstLocalSymbol = 0;
    unsigned NumLocalSymbols = LocalSymbolData.size();
    unsigned FirstExternalSymbol = FirstLocalSymbol + NumLocalSymbols;
    unsigned NumExternalSymbols = ExternalSymbolData.size();
    unsigned FirstUndefinedSymbol = FirstExternalSymbol + NumExternalSymbols;
    unsigned NumUndefinedSymbols = UndefinedSymbolData.size();
    unsigned NumIndirectSymbols = Asm.indirect_symbol_size();
    unsigned NumSymTabSymbols =
      NumLocalSymbols + NumExternalSymbols + NumUndefinedSymbols;
    uint64_t IndirectSymbolSize = NumIndirectSymbols * 4;
    uint64_t IndirectSymbolOffset = 0;

    // If used, the indirect symbols are written after the section data.
    if (NumIndirectSymbols)
      IndirectSymbolOffset = LOHTableEnd;

    // The symbol table is written after the indirect symbol data.
    uint64_t SymbolTableOffset = LOHTableEnd + IndirectSymbolSize;

    // The string table is written after symbol table.
    uint64_t StringTableOffset =
      SymbolTableOffset + NumSymTabSymbols * (is64Bit() ?
                                              sizeof(MachO::nlist_64) :
                                              sizeof(MachO::nlist));
    writeSymtabLoadCommand(SymbolTableOffset, NumSymTabSymbols,
                           StringTableOffset, StringTable.data().size());

    writeDysymtabLoadCommand(FirstLocalSymbol, NumLocalSymbols,
                             FirstExternalSymbol, NumExternalSymbols,
                             FirstUndefinedSymbol, NumUndefinedSymbols,
                             IndirectSymbolOffset, NumIndirectSymbols);
  }

  // Write the linker options load commands.
  for (const auto &Option : Asm.getLinkerOptions())
    writeLinkerOptionsLoadCommand(Option);

  // Write the actual section data.
  for (const MCSection &Sec : Asm) {
    Asm.writeSectionData(&Sec, Layout);

    uint64_t Pad = getPaddingSize(&Sec, Layout);
    WriteZeros(Pad);
  }

  // Write the extra padding.
  WriteZeros(SectionDataPadding);

  // Write the relocation entries.
  for (const MCSection &Sec : Asm) {
    // Write the section relocation entries, in reverse order to match 'as'
    // (approximately, the exact algorithm is more complicated than this).
    std::vector<RelAndSymbol> &Relocs = Relocations[&Sec];
    for (const RelAndSymbol &Rel : make_range(Relocs.rbegin(), Relocs.rend())) {
      write32(Rel.MRE.r_word0);
      write32(Rel.MRE.r_word1);
    }
  }

  // Write out the data-in-code region payload, if there is one.
  for (MCAssembler::const_data_region_iterator
         it = Asm.data_region_begin(), ie = Asm.data_region_end();
         it != ie; ++it) {
    const DataRegionData *Data = &(*it);
    uint64_t Start = getSymbolAddress(*Data->Start, Layout);
    uint64_t End = getSymbolAddress(*Data->End, Layout);
    DEBUG(dbgs() << "data in code region-- kind: " << Data->Kind
                 << "  start: " << Start << "(" << Data->Start->getName() << ")"
                 << "  end: " << End << "(" << Data->End->getName() << ")"
                 << "  size: " << End - Start
                 << "\n");
    write32(Start);
    write16(End - Start);
    write16(Data->Kind);
  }

  // Write out the loh commands, if there is one.
  if (LOHSize) {
#ifndef NDEBUG
    unsigned Start = getStream().tell();
#endif
    Asm.getLOHContainer().emit(*this, Layout);
    // Pad to a multiple of the pointer size.
    writeBytes("", OffsetToAlignment(LOHRawSize, is64Bit() ? 8 : 4));
    assert(getStream().tell() - Start == LOHSize);
  }

  // Write the symbol table data, if used.
  if (NumSymbols) {
    // Write the indirect symbol entries.
    for (MCAssembler::const_indirect_symbol_iterator
           it = Asm.indirect_symbol_begin(),
           ie = Asm.indirect_symbol_end(); it != ie; ++it) {
      // Indirect symbols in the non-lazy symbol pointer section have some
      // special handling.
      const MCSectionMachO &Section =
          static_cast<const MCSectionMachO &>(*it->Section);
      if (Section.getType() == MachO::S_NON_LAZY_SYMBOL_POINTERS) {
        // If this symbol is defined and internal, mark it as such.
        if (it->Symbol->isDefined() && !it->Symbol->isExternal()) {
          uint32_t Flags = MachO::INDIRECT_SYMBOL_LOCAL;
          if (it->Symbol->isAbsolute())
            Flags |= MachO::INDIRECT_SYMBOL_ABS;
          write32(Flags);
          continue;
        }
      }

      write32(it->Symbol->getIndex());
    }

    // FIXME: Check that offsets match computed ones.

    // Write the symbol table entries.
    for (auto *SymbolData :
         {&LocalSymbolData, &ExternalSymbolData, &UndefinedSymbolData})
      for (MachSymbolData &Entry : *SymbolData)
        writeNlist(Entry, Layout);

    // Write the string table.
    getStream() << StringTable.data();
  }
}
Exemple #12
0
void MachObjectWriter::WriteObject(MCAssembler &Asm,
                                   const MCAsmLayout &Layout) {
  unsigned NumSections = Asm.size();

  // The section data starts after the header, the segment load command (and
  // section headers) and the symbol table.
  unsigned NumLoadCommands = 1;
  uint64_t LoadCommandsSize = is64Bit() ?
    macho::SegmentLoadCommand64Size + NumSections * macho::Section64Size :
    macho::SegmentLoadCommand32Size + NumSections * macho::Section32Size;

  // Add the data-in-code load command size, if used.
  unsigned NumDataRegions = Asm.getDataRegions().size();
  if (NumDataRegions) {
    ++NumLoadCommands;
    LoadCommandsSize += macho::LinkeditLoadCommandSize;
  }

  // Add the symbol table load command sizes, if used.
  unsigned NumSymbols = LocalSymbolData.size() + ExternalSymbolData.size() +
    UndefinedSymbolData.size();
  if (NumSymbols) {
    NumLoadCommands += 2;
    LoadCommandsSize += (macho::SymtabLoadCommandSize +
                         macho::DysymtabLoadCommandSize);
  }

  // Add the linker option load commands sizes.
  const std::vector<std::vector<std::string> > &LinkerOptions =
    Asm.getLinkerOptions();
  for (unsigned i = 0, e = LinkerOptions.size(); i != e; ++i) {
    ++NumLoadCommands;
    LoadCommandsSize += ComputeLinkerOptionsLoadCommandSize(LinkerOptions[i],
                                                            is64Bit());
  }
  
  // Compute the total size of the section data, as well as its file size and vm
  // size.
  uint64_t SectionDataStart = (is64Bit() ? macho::Header64Size :
                               macho::Header32Size) + LoadCommandsSize;
  uint64_t SectionDataSize = 0;
  uint64_t SectionDataFileSize = 0;
  uint64_t VMSize = 0;
  for (MCAssembler::const_iterator it = Asm.begin(),
         ie = Asm.end(); it != ie; ++it) {
    const MCSectionData &SD = *it;
    uint64_t Address = getSectionAddress(&SD);
    uint64_t Size = Layout.getSectionAddressSize(&SD);
    uint64_t FileSize = Layout.getSectionFileSize(&SD);
    FileSize += getPaddingSize(&SD, Layout);

    VMSize = std::max(VMSize, Address + Size);

    if (SD.getSection().isVirtualSection())
      continue;

    SectionDataSize = std::max(SectionDataSize, Address + Size);
    SectionDataFileSize = std::max(SectionDataFileSize, Address + FileSize);
  }

  // The section data is padded to 4 bytes.
  //
  // FIXME: Is this machine dependent?
  unsigned SectionDataPadding = OffsetToAlignment(SectionDataFileSize, 4);
  SectionDataFileSize += SectionDataPadding;

  // Write the prolog, starting with the header and load command...
  WriteHeader(NumLoadCommands, LoadCommandsSize,
              Asm.getSubsectionsViaSymbols());
  WriteSegmentLoadCommand(NumSections, VMSize,
                          SectionDataStart, SectionDataSize);

  // ... and then the section headers.
  uint64_t RelocTableEnd = SectionDataStart + SectionDataFileSize;
  for (MCAssembler::const_iterator it = Asm.begin(),
         ie = Asm.end(); it != ie; ++it) {
    std::vector<macho::RelocationEntry> &Relocs = Relocations[it];
    unsigned NumRelocs = Relocs.size();
    uint64_t SectionStart = SectionDataStart + getSectionAddress(it);
    WriteSection(Asm, Layout, *it, SectionStart, RelocTableEnd, NumRelocs);
    RelocTableEnd += NumRelocs * macho::RelocationInfoSize;
  }

  // Write the data-in-code load command, if used.
  uint64_t DataInCodeTableEnd = RelocTableEnd + NumDataRegions * 8;
  if (NumDataRegions) {
    uint64_t DataRegionsOffset = RelocTableEnd;
    uint64_t DataRegionsSize = NumDataRegions * 8;
    WriteLinkeditLoadCommand(macho::LCT_DataInCode, DataRegionsOffset,
                             DataRegionsSize);
  }

  // Write the symbol table load command, if used.
  if (NumSymbols) {
    unsigned FirstLocalSymbol = 0;
    unsigned NumLocalSymbols = LocalSymbolData.size();
    unsigned FirstExternalSymbol = FirstLocalSymbol + NumLocalSymbols;
    unsigned NumExternalSymbols = ExternalSymbolData.size();
    unsigned FirstUndefinedSymbol = FirstExternalSymbol + NumExternalSymbols;
    unsigned NumUndefinedSymbols = UndefinedSymbolData.size();
    unsigned NumIndirectSymbols = Asm.indirect_symbol_size();
    unsigned NumSymTabSymbols =
      NumLocalSymbols + NumExternalSymbols + NumUndefinedSymbols;
    uint64_t IndirectSymbolSize = NumIndirectSymbols * 4;
    uint64_t IndirectSymbolOffset = 0;

    // If used, the indirect symbols are written after the section data.
    if (NumIndirectSymbols)
      IndirectSymbolOffset = DataInCodeTableEnd;

    // The symbol table is written after the indirect symbol data.
    uint64_t SymbolTableOffset = DataInCodeTableEnd + IndirectSymbolSize;

    // The string table is written after symbol table.
    uint64_t StringTableOffset =
      SymbolTableOffset + NumSymTabSymbols * (is64Bit() ? macho::Nlist64Size :
                                              macho::Nlist32Size);
    WriteSymtabLoadCommand(SymbolTableOffset, NumSymTabSymbols,
                           StringTableOffset, StringTable.size());

    WriteDysymtabLoadCommand(FirstLocalSymbol, NumLocalSymbols,
                             FirstExternalSymbol, NumExternalSymbols,
                             FirstUndefinedSymbol, NumUndefinedSymbols,
                             IndirectSymbolOffset, NumIndirectSymbols);
  }

  // Write the linker options load commands.
  for (unsigned i = 0, e = LinkerOptions.size(); i != e; ++i) {
    WriteLinkerOptionsLoadCommand(LinkerOptions[i]);
  }

  // Write the actual section data.
  for (MCAssembler::const_iterator it = Asm.begin(),
         ie = Asm.end(); it != ie; ++it) {
    Asm.writeSectionData(it, Layout);

    uint64_t Pad = getPaddingSize(it, Layout);
    for (unsigned int i = 0; i < Pad; ++i)
      Write8(0);
  }

  // Write the extra padding.
  WriteZeros(SectionDataPadding);

  // Write the relocation entries.
  for (MCAssembler::const_iterator it = Asm.begin(),
         ie = Asm.end(); it != ie; ++it) {
    // Write the section relocation entries, in reverse order to match 'as'
    // (approximately, the exact algorithm is more complicated than this).
    std::vector<macho::RelocationEntry> &Relocs = Relocations[it];
    for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
      Write32(Relocs[e - i - 1].Word0);
      Write32(Relocs[e - i - 1].Word1);
    }
  }

  // Write out the data-in-code region payload, if there is one.
  for (MCAssembler::const_data_region_iterator
         it = Asm.data_region_begin(), ie = Asm.data_region_end();
         it != ie; ++it) {
    const DataRegionData *Data = &(*it);
    uint64_t Start =
      getSymbolAddress(&Layout.getAssembler().getSymbolData(*Data->Start),
                       Layout);
    uint64_t End =
      getSymbolAddress(&Layout.getAssembler().getSymbolData(*Data->End),
                       Layout);
    DEBUG(dbgs() << "data in code region-- kind: " << Data->Kind
                 << "  start: " << Start << "(" << Data->Start->getName() << ")"
                 << "  end: " << End << "(" << Data->End->getName() << ")"
                 << "  size: " << End - Start
                 << "\n");
    Write32(Start);
    Write16(End - Start);
    Write16(Data->Kind);
  }

  // Write the symbol table data, if used.
  if (NumSymbols) {
    // Write the indirect symbol entries.
    for (MCAssembler::const_indirect_symbol_iterator
           it = Asm.indirect_symbol_begin(),
           ie = Asm.indirect_symbol_end(); it != ie; ++it) {
      // Indirect symbols in the non lazy symbol pointer section have some
      // special handling.
      const MCSectionMachO &Section =
        static_cast<const MCSectionMachO&>(it->SectionData->getSection());
      if (Section.getType() == MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS) {
        // If this symbol is defined and internal, mark it as such.
        if (it->Symbol->isDefined() &&
            !Asm.getSymbolData(*it->Symbol).isExternal()) {
          uint32_t Flags = macho::ISF_Local;
          if (it->Symbol->isAbsolute())
            Flags |= macho::ISF_Absolute;
          Write32(Flags);
          continue;
        }
      }

      Write32(Asm.getSymbolData(*it->Symbol).getIndex());
    }

    // FIXME: Check that offsets match computed ones.

    // Write the symbol table entries.
    for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
      WriteNlist(LocalSymbolData[i], Layout);
    for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i)
      WriteNlist(ExternalSymbolData[i], Layout);
    for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i)
      WriteNlist(UndefinedSymbolData[i], Layout);

    // Write the string table.
    OS << StringTable.str();
  }
}
void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
                                      const MCAsmLayout &Layout) {
  // Assign symbol and section indexes and offsets.
  Header.NumberOfSections = 0;

  DenseMap<COFFSection *, uint16_t> SectionIndices;
  for (sections::iterator i = Sections.begin(),
                          e = Sections.end(); i != e; i++) {
    if (Layout.getSectionAddressSize((*i)->MCData) > 0) {
      size_t Number = ++Header.NumberOfSections;
      SectionIndices[*i] = Number;
      MakeSectionReal(**i, Number);
    } else {
      (*i)->Number = -1;
    }
  }

  Header.NumberOfSymbols = 0;

  for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
    COFFSymbol *coff_symbol = *i;
    MCSymbolData const *SymbolData = coff_symbol->MCData;

    // Update section number & offset for symbols that have them.
    if ((SymbolData != NULL) && (SymbolData->Fragment != NULL)) {
      assert(coff_symbol->Section != NULL);

      coff_symbol->Data.SectionNumber = coff_symbol->Section->Number;
      coff_symbol->Data.Value = Layout.getFragmentOffset(SymbolData->Fragment)
                              + SymbolData->Offset;
    }

    if (coff_symbol->should_keep()) {
      MakeSymbolReal(*coff_symbol, Header.NumberOfSymbols++);

      // Update auxiliary symbol info.
      coff_symbol->Data.NumberOfAuxSymbols = coff_symbol->Aux.size();
      Header.NumberOfSymbols += coff_symbol->Data.NumberOfAuxSymbols;
    } else
      coff_symbol->Index = -1;
  }

  // Fixup weak external references.
  for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
    COFFSymbol *coff_symbol = *i;
    if (coff_symbol->Other != NULL) {
      assert(coff_symbol->Index != -1);
      assert(coff_symbol->Aux.size() == 1 &&
             "Symbol must contain one aux symbol!");
      assert(coff_symbol->Aux[0].AuxType == ATWeakExternal &&
             "Symbol's aux symbol must be a Weak External!");
      coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = coff_symbol->Other->Index;
    }
  }

  // Fixup associative COMDAT sections.
  for (sections::iterator i = Sections.begin(),
                          e = Sections.end(); i != e; i++) {
    if ((*i)->Symbol->Aux[0].Aux.SectionDefinition.Selection !=
        COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE)
      continue;

    const MCSectionCOFF &MCSec = static_cast<const MCSectionCOFF &>(
                                                    (*i)->MCData->getSection());

    COFFSection *Assoc = SectionMap.lookup(MCSec.getAssocSection());
    if (!Assoc) {
      report_fatal_error(Twine("Missing associated COMDAT section ") +
                         MCSec.getAssocSection()->getSectionName() +
                         " for section " + MCSec.getSectionName());
    }

    // Skip this section if the associated section is unused.
    if (Assoc->Number == -1)
      continue;

    (*i)->Symbol->Aux[0].Aux.SectionDefinition.Number = SectionIndices[Assoc];
  }


  // Assign file offsets to COFF object file structures.

  unsigned offset = 0;

  offset += COFF::HeaderSize;
  offset += COFF::SectionSize * Header.NumberOfSections;

  for (MCAssembler::const_iterator i = Asm.begin(),
                                   e = Asm.end();
                                   i != e; i++) {
    COFFSection *Sec = SectionMap[&i->getSection()];

    if (Sec->Number == -1)
      continue;

    Sec->Header.SizeOfRawData = Layout.getSectionAddressSize(i);

    if (IsPhysicalSection(Sec)) {
      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 NumberOfSections 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 (relocations::iterator cr = Sec->Relocations.begin(),
                                 er = Sec->Relocations.end();
                                 cr != er; ++cr) {
        assert((*cr).Symb->Index != -1);
        (*cr).Data.SymbolTableIndex = (*cr).Symb->Index;
      }
    }

    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;

  Header.TimeDateStamp = sys::TimeValue::now().toEpochTime();

  // Write it all to disk...
  WriteFileHeader(Header);

  {
    sections::iterator i, ie;
    MCAssembler::const_iterator j, je;

    for (i = Sections.begin(), ie = Sections.end(); i != ie; i++)
      if ((*i)->Number != -1) {
        if ((*i)->Relocations.size() >= 0xffff) {
          (*i)->Header.Characteristics |= COFF::IMAGE_SCN_LNK_NRELOC_OVFL;
        }
        WriteSectionHeader((*i)->Header);
      }

    for (i = Sections.begin(), ie = Sections.end(),
         j = Asm.begin(), je = Asm.end();
         (i != ie) && (j != je); ++i, ++j) {

      if ((*i)->Number == -1)
        continue;

      if ((*i)->Header.PointerToRawData != 0) {
        assert(OS.tell() == (*i)->Header.PointerToRawData &&
               "Section::PointerToRawData is insane!");

        Asm.writeSectionData(j, Layout);
      }

      if ((*i)->Relocations.size() > 0) {
        assert(OS.tell() == (*i)->Header.PointerToRelocations &&
               "Section::PointerToRelocations is insane!");

        if ((*i)->Relocations.size() >= 0xffff) {
          // In case of overflow, write actual relocation count as first
          // relocation. Including the synthetic reloc itself (+ 1).
          COFF::relocation r;
          r.VirtualAddress = (*i)->Relocations.size() + 1;
          r.SymbolTableIndex = 0;
          r.Type = 0;
          WriteRelocation(r);
        }

        for (relocations::const_iterator k = (*i)->Relocations.begin(),
                                               ke = (*i)->Relocations.end();
                                               k != ke; k++) {
          WriteRelocation(k->Data);
        }
      } else
        assert((*i)->Header.PointerToRelocations == 0 &&
               "Section::PointerToRelocations is insane!");
    }
  }

  assert(OS.tell() == Header.PointerToSymbolTable &&
         "Header::PointerToSymbolTable is insane!");

  for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++)
    if ((*i)->Index != -1)
      WriteSymbol(*i);

  OS.write((char const *)&Strings.Data.front(), Strings.Data.size());
}
void MachObjectWriter::WriteObject(MCAssembler &Asm,
                                   const MCAsmLayout &Layout) {
  unsigned NumSections = Asm.size();
  const MCAssembler::VersionMinInfoType &VersionInfo =
    Layout.getAssembler().getVersionMinInfo();

  // The section data starts after the header, the segment load command (and
  // section headers) and the symbol table.
  unsigned NumLoadCommands = 1;
  uint64_t LoadCommandsSize = is64Bit() ?
    sizeof(MachO::segment_command_64) + NumSections * sizeof(MachO::section_64):
    sizeof(MachO::segment_command) + NumSections * sizeof(MachO::section);

  // Add the deployment target version info load command size, if used.
  if (VersionInfo.Major != 0) {
    ++NumLoadCommands;
    LoadCommandsSize += sizeof(MachO::version_min_command);
  }

  // Add the data-in-code load command size, if used.
  unsigned NumDataRegions = Asm.getDataRegions().size();
  if (NumDataRegions) {
    ++NumLoadCommands;
    LoadCommandsSize += sizeof(MachO::linkedit_data_command);
  }

  // Add the loh load command size, if used.
  uint64_t LOHRawSize = Asm.getLOHContainer().getEmitSize(*this, Layout);
  uint64_t LOHSize = RoundUpToAlignment(LOHRawSize, is64Bit() ? 8 : 4);
  if (LOHSize) {
    ++NumLoadCommands;
    LoadCommandsSize += sizeof(MachO::linkedit_data_command);
  }

  // Add the symbol table load command sizes, if used.
  unsigned NumSymbols = LocalSymbolData.size() + ExternalSymbolData.size() +
    UndefinedSymbolData.size();
  if (NumSymbols) {
    NumLoadCommands += 2;
    LoadCommandsSize += (sizeof(MachO::symtab_command) +
                         sizeof(MachO::dysymtab_command));
  }

  // Add the linker option load commands sizes.
  const std::vector<std::vector<std::string> > &LinkerOptions =
    Asm.getLinkerOptions();
  for (unsigned i = 0, e = LinkerOptions.size(); i != e; ++i) {
    ++NumLoadCommands;
    LoadCommandsSize += ComputeLinkerOptionsLoadCommandSize(LinkerOptions[i],
                                                            is64Bit());
  }
  
  // Compute the total size of the section data, as well as its file size and vm
  // size.
  uint64_t SectionDataStart = (is64Bit() ? sizeof(MachO::mach_header_64) :
                               sizeof(MachO::mach_header)) + LoadCommandsSize;
  uint64_t SectionDataSize = 0;
  uint64_t SectionDataFileSize = 0;
  uint64_t VMSize = 0;
  for (MCAssembler::const_iterator it = Asm.begin(),
         ie = Asm.end(); it != ie; ++it) {
    const MCSectionData &SD = *it;
    uint64_t Address = getSectionAddress(&SD);
    uint64_t Size = Layout.getSectionAddressSize(&SD);
    uint64_t FileSize = Layout.getSectionFileSize(&SD);
    FileSize += getPaddingSize(&SD, Layout);

    VMSize = std::max(VMSize, Address + Size);

    if (SD.getSection().isVirtualSection())
      continue;

    SectionDataSize = std::max(SectionDataSize, Address + Size);
    SectionDataFileSize = std::max(SectionDataFileSize, Address + FileSize);
  }

  // The section data is padded to 4 bytes.
  //
  // FIXME: Is this machine dependent?
  unsigned SectionDataPadding = OffsetToAlignment(SectionDataFileSize, 4);
  SectionDataFileSize += SectionDataPadding;

  // Write the prolog, starting with the header and load command...
  WriteHeader(NumLoadCommands, LoadCommandsSize,
              Asm.getSubsectionsViaSymbols());
  WriteSegmentLoadCommand(NumSections, VMSize,
                          SectionDataStart, SectionDataSize);

  // ... and then the section headers.
  uint64_t RelocTableEnd = SectionDataStart + SectionDataFileSize;
  for (MCAssembler::const_iterator it = Asm.begin(),
         ie = Asm.end(); it != ie; ++it) {
    std::vector<MachO::any_relocation_info> &Relocs = Relocations[it];
    unsigned NumRelocs = Relocs.size();
    uint64_t SectionStart = SectionDataStart + getSectionAddress(it);
    WriteSection(Asm, Layout, *it, SectionStart, RelocTableEnd, NumRelocs);
    RelocTableEnd += NumRelocs * sizeof(MachO::any_relocation_info);
  }

  // Write out the deployment target information, if it's available.
  if (VersionInfo.Major != 0) {
    assert(VersionInfo.Update < 256 && "unencodable update target version");
    assert(VersionInfo.Minor < 256 && "unencodable minor target version");
    assert(VersionInfo.Major < 65536 && "unencodable major target version");
    uint32_t EncodedVersion = VersionInfo.Update | (VersionInfo.Minor << 8) |
      (VersionInfo.Major << 16);
    Write32(VersionInfo.Kind == MCVM_OSXVersionMin ? MachO::LC_VERSION_MIN_MACOSX :
            MachO::LC_VERSION_MIN_IPHONEOS);
    Write32(sizeof(MachO::version_min_command));
    Write32(EncodedVersion);
    Write32(0);         // reserved.
  }

  // Write the data-in-code load command, if used.
  uint64_t DataInCodeTableEnd = RelocTableEnd + NumDataRegions * 8;
  if (NumDataRegions) {
    uint64_t DataRegionsOffset = RelocTableEnd;
    uint64_t DataRegionsSize = NumDataRegions * 8;
    WriteLinkeditLoadCommand(MachO::LC_DATA_IN_CODE, DataRegionsOffset,
                             DataRegionsSize);
  }

  // Write the loh load command, if used.
  uint64_t LOHTableEnd = DataInCodeTableEnd + LOHSize;
  if (LOHSize)
    WriteLinkeditLoadCommand(MachO::LC_LINKER_OPTIMIZATION_HINT,
                             DataInCodeTableEnd, LOHSize);

  // Write the symbol table load command, if used.
  if (NumSymbols) {
    unsigned FirstLocalSymbol = 0;
    unsigned NumLocalSymbols = LocalSymbolData.size();
    unsigned FirstExternalSymbol = FirstLocalSymbol + NumLocalSymbols;
    unsigned NumExternalSymbols = ExternalSymbolData.size();
    unsigned FirstUndefinedSymbol = FirstExternalSymbol + NumExternalSymbols;
    unsigned NumUndefinedSymbols = UndefinedSymbolData.size();
    unsigned NumIndirectSymbols = Asm.indirect_symbol_size();
    unsigned NumSymTabSymbols =
      NumLocalSymbols + NumExternalSymbols + NumUndefinedSymbols;
    uint64_t IndirectSymbolSize = NumIndirectSymbols * 4;
    uint64_t IndirectSymbolOffset = 0;

    // If used, the indirect symbols are written after the section data.
    if (NumIndirectSymbols)
      IndirectSymbolOffset = LOHTableEnd;

    // The symbol table is written after the indirect symbol data.
    uint64_t SymbolTableOffset = LOHTableEnd + IndirectSymbolSize;

    // The string table is written after symbol table.
    uint64_t StringTableOffset =
      SymbolTableOffset + NumSymTabSymbols * (is64Bit() ?
                                              sizeof(MachO::nlist_64) :
                                              sizeof(MachO::nlist));
    WriteSymtabLoadCommand(SymbolTableOffset, NumSymTabSymbols,
                           StringTableOffset, StringTable.data().size());

    WriteDysymtabLoadCommand(FirstLocalSymbol, NumLocalSymbols,
                             FirstExternalSymbol, NumExternalSymbols,
                             FirstUndefinedSymbol, NumUndefinedSymbols,
                             IndirectSymbolOffset, NumIndirectSymbols);
  }

  // Write the linker options load commands.
  for (unsigned i = 0, e = LinkerOptions.size(); i != e; ++i) {
    WriteLinkerOptionsLoadCommand(LinkerOptions[i]);
  }

  // Write the actual section data.
  for (MCAssembler::const_iterator it = Asm.begin(),
         ie = Asm.end(); it != ie; ++it) {
    Asm.writeSectionData(it, Layout);

    uint64_t Pad = getPaddingSize(it, Layout);
    for (unsigned int i = 0; i < Pad; ++i)
      Write8(0);
  }

  // Write the extra padding.
  WriteZeros(SectionDataPadding);

  // Write the relocation entries.
  for (MCAssembler::const_iterator it = Asm.begin(),
         ie = Asm.end(); it != ie; ++it) {
    // Write the section relocation entries, in reverse order to match 'as'
    // (approximately, the exact algorithm is more complicated than this).
    std::vector<MachO::any_relocation_info> &Relocs = Relocations[it];
    for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
      Write32(Relocs[e - i - 1].r_word0);
      Write32(Relocs[e - i - 1].r_word1);
    }
  }

  // Write out the data-in-code region payload, if there is one.
  for (MCAssembler::const_data_region_iterator
         it = Asm.data_region_begin(), ie = Asm.data_region_end();
         it != ie; ++it) {
    const DataRegionData *Data = &(*it);
    uint64_t Start =
      getSymbolAddress(&Layout.getAssembler().getSymbolData(*Data->Start),
                       Layout);
    uint64_t End =
      getSymbolAddress(&Layout.getAssembler().getSymbolData(*Data->End),
                       Layout);
    DEBUG(dbgs() << "data in code region-- kind: " << Data->Kind
                 << "  start: " << Start << "(" << Data->Start->getName() << ")"
                 << "  end: " << End << "(" << Data->End->getName() << ")"
                 << "  size: " << End - Start
                 << "\n");
    Write32(Start);
    Write16(End - Start);
    Write16(Data->Kind);
  }

  // Write out the loh commands, if there is one.
  if (LOHSize) {
#ifndef NDEBUG
    unsigned Start = OS.tell();
#endif
    Asm.getLOHContainer().Emit(*this, Layout);
    // Pad to a multiple of the pointer size.
    WriteBytes("", OffsetToAlignment(LOHRawSize, is64Bit() ? 8 : 4));
    assert(OS.tell() - Start == LOHSize);
  }

  // Write the symbol table data, if used.
  if (NumSymbols) {
    // Write the indirect symbol entries.
    for (MCAssembler::const_indirect_symbol_iterator
           it = Asm.indirect_symbol_begin(),
           ie = Asm.indirect_symbol_end(); it != ie; ++it) {
      // Indirect symbols in the non-lazy symbol pointer section have some
      // special handling.
      const MCSectionMachO &Section =
        static_cast<const MCSectionMachO&>(it->SectionData->getSection());
      if (Section.getType() == MachO::S_NON_LAZY_SYMBOL_POINTERS) {
        // If this symbol is defined and internal, mark it as such.
        if (it->Symbol->isDefined() &&
            !Asm.getSymbolData(*it->Symbol).isExternal()) {
          uint32_t Flags = MachO::INDIRECT_SYMBOL_LOCAL;
          if (it->Symbol->isAbsolute())
            Flags |= MachO::INDIRECT_SYMBOL_ABS;
          Write32(Flags);
          continue;
        }
      }

      Write32(Asm.getSymbolData(*it->Symbol).getIndex());
    }

    // FIXME: Check that offsets match computed ones.

    // Write the symbol table entries.
    for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
      WriteNlist(LocalSymbolData[i], Layout);
    for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i)
      WriteNlist(ExternalSymbolData[i], Layout);
    for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i)
      WriteNlist(UndefinedSymbolData[i], Layout);

    // Write the string table.
    OS << StringTable.data();
  }
}
void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
                                      const MCAsmLayout &Layout) {
  // Assign symbol and section indexes and offsets.
  Header.NumberOfSections = 0;

  for (sections::iterator i = Sections.begin(),
                          e = Sections.end(); i != e; i++) {
    if (Layout.getSectionAddressSize((*i)->MCData) > 0) {
      MakeSectionReal(**i, ++Header.NumberOfSections);
    } else {
      (*i)->Number = -1;
    }
  }

  Header.NumberOfSymbols = 0;

  for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
    COFFSymbol *coff_symbol = *i;
    MCSymbolData const *SymbolData = coff_symbol->MCData;

    // Update section number & offset for symbols that have them.
    if ((SymbolData != NULL) && (SymbolData->Fragment != NULL)) {
      assert(coff_symbol->Section != NULL);

      coff_symbol->Data.SectionNumber = coff_symbol->Section->Number;
      coff_symbol->Data.Value = Layout.getFragmentOffset(SymbolData->Fragment)
                              + SymbolData->Offset;
    }

    if (coff_symbol->should_keep()) {
      MakeSymbolReal(*coff_symbol, Header.NumberOfSymbols++);

      // Update auxiliary symbol info.
      coff_symbol->Data.NumberOfAuxSymbols = coff_symbol->Aux.size();
      Header.NumberOfSymbols += coff_symbol->Data.NumberOfAuxSymbols;
    } else
      coff_symbol->Index = -1;
  }

  // Fixup weak external references.
  for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
    COFFSymbol *coff_symbol = *i;
    if (coff_symbol->Other != NULL) {
      assert(coff_symbol->Index != -1);
      assert(coff_symbol->Aux.size() == 1 &&
             "Symbol must contain one aux symbol!");
      assert(coff_symbol->Aux[0].AuxType == ATWeakExternal &&
             "Symbol's aux symbol must be a Weak External!");
      coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = coff_symbol->Other->Index;
    }
  }

  // Assign file offsets to COFF object file structures.

  unsigned offset = 0;

  offset += COFF::HeaderSize;
  offset += COFF::SectionSize * Header.NumberOfSections;

  for (MCAssembler::const_iterator i = Asm.begin(),
                                   e = Asm.end();
                                   i != e; i++) {
    COFFSection *Sec = SectionMap[&i->getSection()];

    if (Sec->Number == -1)
      continue;

    Sec->Header.SizeOfRawData = Layout.getSectionAddressSize(i);

    if (IsPhysicalSection(Sec)) {
      Sec->Header.PointerToRawData = offset;

      offset += Sec->Header.SizeOfRawData;
    }

    if (Sec->Relocations.size() > 0) {
      Sec->Header.NumberOfRelocations = Sec->Relocations.size();
      Sec->Header.PointerToRelocations = offset;

      offset += COFF::RelocationSize * Sec->Relocations.size();

      for (relocations::iterator cr = Sec->Relocations.begin(),
                                 er = Sec->Relocations.end();
                                 cr != er; ++cr) {
        assert((*cr).Symb->Index != -1);
        (*cr).Data.SymbolTableIndex = (*cr).Symb->Index;
      }
    }

    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;

  Header.TimeDateStamp = sys::TimeValue::now().toEpochTime();

  // Write it all to disk...
  WriteFileHeader(Header);

  {
    sections::iterator i, ie;
    MCAssembler::const_iterator j, je;

    for (i = Sections.begin(), ie = Sections.end(); i != ie; i++)
      if ((*i)->Number != -1)
        WriteSectionHeader((*i)->Header);

    for (i = Sections.begin(), ie = Sections.end(),
         j = Asm.begin(), je = Asm.end();
         (i != ie) && (j != je); ++i, ++j) {

      if ((*i)->Number == -1)
        continue;

      if ((*i)->Header.PointerToRawData != 0) {
        assert(OS.tell() == (*i)->Header.PointerToRawData &&
               "Section::PointerToRawData is insane!");

        Asm.writeSectionData(j, Layout);
      }

      if ((*i)->Relocations.size() > 0) {
        assert(OS.tell() == (*i)->Header.PointerToRelocations &&
               "Section::PointerToRelocations is insane!");

        for (relocations::const_iterator k = (*i)->Relocations.begin(),
                                               ke = (*i)->Relocations.end();
                                               k != ke; k++) {
          WriteRelocation(k->Data);
        }
      } else
        assert((*i)->Header.PointerToRelocations == 0 &&
               "Section::PointerToRelocations is insane!");
    }
  }

  assert(OS.tell() == Header.PointerToSymbolTable &&
         "Header::PointerToSymbolTable is insane!");

  for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++)
    if ((*i)->Index != -1)
      WriteSymbol(*i);

  OS.write((char const *)&Strings.Data.front(), Strings.Data.size());
}