C++ iterator::getSection方法代码示例

MCAsmLayout::MCAsmLayout(MCAssembler &Asm)
  : Assembler(Asm), LastValidFragment()
 {
  // Compute the section layout order. Virtual sections must go last.
  for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it)
    if (!it->getSection().isVirtualSection())
      SectionOrder.push_back(&*it);
  for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it)
    if (it->getSection().isVirtualSection())
      SectionOrder.push_back(&*it);
}

/// ComputeSymbolTable - Compute the symbol table data
///
/// \param StringTable [out] - The string table data.
/// \param StringIndexMap [out] - Map from symbol names to offsets in the
/// string table.
void MachObjectWriter::
ComputeSymbolTable(MCAssembler &Asm, SmallString<256> &StringTable,
                   std::vector<MachSymbolData> &LocalSymbolData,
                   std::vector<MachSymbolData> &ExternalSymbolData,
                   std::vector<MachSymbolData> &UndefinedSymbolData) {
  // Build section lookup table.
  DenseMap<const MCSection*, uint8_t> SectionIndexMap;
  unsigned Index = 1;
  for (MCAssembler::iterator it = Asm.begin(),
         ie = Asm.end(); it != ie; ++it, ++Index)
    SectionIndexMap[&it->getSection()] = Index;
  assert(Index <= 256 && "Too many sections!");

  // Index 0 is always the empty string.
  StringMap<uint64_t> StringIndexMap;
  StringTable += '\x00';

  // Build the symbol arrays and the string table, but only for non-local
  // symbols.
  //
  // The particular order that we collect the symbols and create the string
  // table, then sort the symbols is chosen to match 'as'. Even though it
  // doesn't matter for correctness, this is important for letting us diff .o
  // files.
  for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
         ie = Asm.symbol_end(); it != ie; ++it) {
    const MCSymbol &Symbol = it->getSymbol();

    // Ignore non-linker visible symbols.
    if (!Asm.isSymbolLinkerVisible(it->getSymbol()))
      continue;

    if (!it->isExternal() && !Symbol.isUndefined())
      continue;

    uint64_t &Entry = StringIndexMap[Symbol.getName()];
    if (!Entry) {
      Entry = StringTable.size();
      StringTable += Symbol.getName();
      StringTable += '\x00';
    }

    MachSymbolData MSD;
    MSD.SymbolData = it;
    MSD.StringIndex = Entry;

    if (Symbol.isUndefined()) {
      MSD.SectionIndex = 0;
      UndefinedSymbolData.push_back(MSD);
    } else if (Symbol.isAbsolute()) {
      MSD.SectionIndex = 0;
      ExternalSymbolData.push_back(MSD);
    } else {
      MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection());
      assert(MSD.SectionIndex && "Invalid section index!");
      ExternalSymbolData.push_back(MSD);
    }
  }

  // Now add the data for local symbols.
  for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
         ie = Asm.symbol_end(); it != ie; ++it) {
    const MCSymbol &Symbol = it->getSymbol();

    // Ignore non-linker visible symbols.
    if (!Asm.isSymbolLinkerVisible(it->getSymbol()))
      continue;

    if (it->isExternal() || Symbol.isUndefined())
      continue;

    uint64_t &Entry = StringIndexMap[Symbol.getName()];
    if (!Entry) {
      Entry = StringTable.size();
      StringTable += Symbol.getName();
      StringTable += '\x00';
    }

    MachSymbolData MSD;
    MSD.SymbolData = it;
    MSD.StringIndex = Entry;

    if (Symbol.isAbsolute()) {
      MSD.SectionIndex = 0;
      LocalSymbolData.push_back(MSD);
    } else {
      MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection());
      assert(MSD.SectionIndex && "Invalid section index!");
      LocalSymbolData.push_back(MSD);
    }
  }

  // External and undefined symbols are required to be in lexicographic order.
  std::sort(ExternalSymbolData.begin(), ExternalSymbolData.end());
  std::sort(UndefinedSymbolData.begin(), UndefinedSymbolData.end());
//.........这里部分代码省略.........

/// ComputeSymbolTable - Compute the symbol table data
void MachObjectWriter::ComputeSymbolTable(
    MCAssembler &Asm, std::vector<MachSymbolData> &LocalSymbolData,
    std::vector<MachSymbolData> &ExternalSymbolData,
    std::vector<MachSymbolData> &UndefinedSymbolData) {
  // Build section lookup table.
  DenseMap<const MCSection*, uint8_t> SectionIndexMap;
  unsigned Index = 1;
  for (MCAssembler::iterator it = Asm.begin(),
         ie = Asm.end(); it != ie; ++it, ++Index)
    SectionIndexMap[&it->getSection()] = Index;
  assert(Index <= 256 && "Too many sections!");

  // Build the string table.
  for (MCSymbolData &SD : Asm.symbols()) {
    const MCSymbol &Symbol = SD.getSymbol();
    if (!Asm.isSymbolLinkerVisible(Symbol))
      continue;

    StringTable.add(Symbol.getName());
  }
  StringTable.finalize(StringTableBuilder::MachO);

  // Build the symbol arrays but only for non-local symbols.
  //
  // The particular order that we collect and then sort the symbols is chosen to
  // match 'as'. Even though it doesn't matter for correctness, this is
  // important for letting us diff .o files.
  for (MCSymbolData &SD : Asm.symbols()) {
    const MCSymbol &Symbol = SD.getSymbol();

    // Ignore non-linker visible symbols.
    if (!Asm.isSymbolLinkerVisible(Symbol))
      continue;

    if (!SD.isExternal() && !Symbol.isUndefined())
      continue;

    MachSymbolData MSD;
    MSD.SymbolData = &SD;
    MSD.StringIndex = StringTable.getOffset(Symbol.getName());

    if (Symbol.isUndefined()) {
      MSD.SectionIndex = 0;
      UndefinedSymbolData.push_back(MSD);
    } else if (Symbol.isAbsolute()) {
      MSD.SectionIndex = 0;
      ExternalSymbolData.push_back(MSD);
    } else {
      MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection());
      assert(MSD.SectionIndex && "Invalid section index!");
      ExternalSymbolData.push_back(MSD);
    }
  }

  // Now add the data for local symbols.
  for (MCSymbolData &SD : Asm.symbols()) {
    const MCSymbol &Symbol = SD.getSymbol();

    // Ignore non-linker visible symbols.
    if (!Asm.isSymbolLinkerVisible(Symbol))
      continue;

    if (SD.isExternal() || Symbol.isUndefined())
      continue;

    MachSymbolData MSD;
    MSD.SymbolData = &SD;
    MSD.StringIndex = StringTable.getOffset(Symbol.getName());

    if (Symbol.isAbsolute()) {
      MSD.SectionIndex = 0;
      LocalSymbolData.push_back(MSD);
    } else {
      MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection());
      assert(MSD.SectionIndex && "Invalid section index!");
      LocalSymbolData.push_back(MSD);
    }
  }

  // External and undefined symbols are required to be in lexicographic order.
  std::sort(ExternalSymbolData.begin(), ExternalSymbolData.end());
  std::sort(UndefinedSymbolData.begin(), UndefinedSymbolData.end());

  // Set the symbol indices.
  Index = 0;
  for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
    LocalSymbolData[i].SymbolData->setIndex(Index++);
  for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i)
    ExternalSymbolData[i].SymbolData->setIndex(Index++);
  for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i)
    UndefinedSymbolData[i].SymbolData->setIndex(Index++);
}