gold/output.h

// output.h -- manage the output file for gold   -*- C++ -*-

// Copyright (C) 2006-2024 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.

// This file is part of gold.

// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.

#ifndef GOLD_OUTPUT_H
#define GOLD_OUTPUT_H

#include <algorithm>
#include <list>
#include <vector>

#include "elfcpp.h"
#include "mapfile.h"
#include "layout.h"
#include "reloc-types.h"

namespace gold
{

class General_options;
class Object;
class Symbol;
class Output_merge_base;
class Output_section;
class Relocatable_relocs;
class Target;
template<int size, bool big_endian>
class Sized_target;
template<int size, bool big_endian>
class Sized_relobj;
template<int size, bool big_endian>
class Sized_relobj_file;

// This class represents the output file.

class Output_file
{
 public:
  Output_file(const char* name);

  // Indicate that this is a temporary file which should not be
  // output.
  void
  set_is_temporary()
  { this->is_temporary_ = true; }

  // Try to open an existing file. Returns false if the file doesn't
  // exist, has a size of 0 or can't be mmaped.  This method is
  // thread-unsafe.  If BASE_NAME is not NULL, use the contents of
  // that file as the base for incremental linking.
  bool
  open_base_file(const char* base_name, bool writable);

  // Open the output file.  FILE_SIZE is the final size of the file.
  // If the file already exists, it is deleted/truncated.  This method
  // is thread-unsafe.
  void
  open(off_t file_size);

  // Resize the output file.  This method is thread-unsafe.
  void
  resize(off_t file_size);

  // Close the output file (flushing all buffered data) and make sure
  // there are no errors.  This method is thread-unsafe.
  void
  close();

  // Return the size of this file.
  off_t
  filesize()
  { return this->file_size_; }

  // Return the name of this file.
  const char*
  filename()
  { return this->name_; }

  // We currently always use mmap which makes the view handling quite
  // simple.  In the future we may support other approaches.

  // Write data to the output file.
  void
  write(off_t offset, const void* data, size_t len)
  { memcpy(this->base_ + offset, data, len); }

  // Get a buffer to use to write to the file, given the offset into
  // the file and the size.
  unsigned char*
  get_output_view(off_t start, size_t size)
  {
    gold_assert(start >= 0
		&& start + static_cast<off_t>(size) <= this->file_size_);
    return this->base_ + start;
  }

  // VIEW must have been returned by get_output_view.  Write the
  // buffer to the file, passing in the offset and the size.
  void
  write_output_view(off_t, size_t, unsigned char*)
  { }

  // Get a read/write buffer.  This is used when we want to write part
  // of the file, read it in, and write it again.
  unsigned char*
  get_input_output_view(off_t start, size_t size)
  { return this->get_output_view(start, size); }

  // Write a read/write buffer back to the file.
  void
  write_input_output_view(off_t, size_t, unsigned char*)
  { }

  // Get a read buffer.  This is used when we just want to read part
  // of the file back it in.
  const unsigned char*
  get_input_view(off_t start, size_t size)
  { return this->get_output_view(start, size); }

  // Release a read bfufer.
  void
  free_input_view(off_t, size_t, const unsigned char*)
  { }

 private:
  // Map the file into memory or, if that fails, allocate anonymous
  // memory.
  void
  map();

  // Allocate anonymous memory for the file.
  bool
  map_anonymous();

  // Map the file into memory.
  bool
  map_no_anonymous(bool);

  // Unmap the file from memory (and flush to disk buffers).
  void
  unmap();

  // File name.
  const char* name_;
  // File descriptor.
  int o_;
  // File size.
  off_t file_size_;
  // Base of file mapped into memory.
  unsigned char* base_;
  // True iff base_ points to a memory buffer rather than an output file.
  bool map_is_anonymous_;
  // True if base_ was allocated using new rather than mmap.
  bool map_is_allocated_;
  // True if this is a temporary file which should not be output.
  bool is_temporary_;
};

// An abtract class for data which has to go into the output file.

class Output_data
{
 public:
  explicit Output_data()
    : address_(0), data_size_(0), offset_(-1),
      is_address_valid_(false), is_data_size_valid_(false),
      is_offset_valid_(false), is_data_size_fixed_(false),
      has_dynamic_reloc_(false)
  { }

  virtual
  ~Output_data();

  // Return the address.  For allocated sections, this is only valid
  // after Layout::finalize is finished.
  uint64_t
  address() const
  {
    gold_assert(this->is_address_valid_);
    return this->address_;
  }

  // Return the size of the data.  For allocated sections, this must
  // be valid after Layout::finalize calls set_address, but need not
  // be valid before then.
  off_t
  data_size() const
  {
    gold_assert(this->is_data_size_valid_);
    return this->data_size_;
  }

  // Get the current data size.
  off_t
  current_data_size() const
  { return this->current_data_size_for_child(); }

  // Return true if data size is fixed.
  bool
  is_data_size_fixed() const
  { return this->is_data_size_fixed_; }

  // Return the file offset.  This is only valid after
  // Layout::finalize is finished.  For some non-allocated sections,
  // it may not be valid until near the end of the link.
  off_t
  offset() const
  {
    gold_assert(this->is_offset_valid_);
    return this->offset_;
  }

  // Reset the address, file offset and data size.  This essentially
  // disables the sanity testing about duplicate and unknown settings.
  void
  reset_address_and_file_offset()
  {
    this->is_address_valid_ = false;
    this->is_offset_valid_ = false;
    if (!this->is_data_size_fixed_)
      this->is_data_size_valid_ = false;
    this->do_reset_address_and_file_offset();
  }

  // As above, but just for data size.
  void
  reset_data_size()
  {
    if (!this->is_data_size_fixed_)
      this->is_data_size_valid_ = false;
  }

  // Return true if address and file offset already have reset values. In
  // other words, calling reset_address_and_file_offset will not change them.
  bool
  address_and_file_offset_have_reset_values() const
  { return this->do_address_and_file_offset_have_reset_values(); }

  // Return the required alignment.
  uint64_t
  addralign() const
  { return this->do_addralign(); }

  // Return whether this has a load address.
  bool
  has_load_address() const
  { return this->do_has_load_address(); }

  // Return the load address.
  uint64_t
  load_address() const
  { return this->do_load_address(); }

  // Return whether this is an Output_section.
  bool
  is_section() const
  { return this->do_is_section(); }

  // Return whether this is an Output_section of the specified type.
  bool
  is_section_type(elfcpp::Elf_Word stt) const
  { return this->do_is_section_type(stt); }

  // Return whether this is an Output_section with the specified flag
  // set.
  bool
  is_section_flag_set(elfcpp::Elf_Xword shf) const
  { return this->do_is_section_flag_set(shf); }

  // Return the output section that this goes in, if there is one.
  Output_section*
  output_section()
  { return this->do_output_section(); }

  const Output_section*
  output_section() const
  { return this->do_output_section(); }

  // Return the output section index, if there is an output section.
  unsigned int
  out_shndx() const
  { return this->do_out_shndx(); }

  // Set the output section index, if this is an output section.
  void
  set_out_shndx(unsigned int shndx)
  { this->do_set_out_shndx(shndx); }

  // Set the address and file offset of this data, and finalize the
  // size of the data.  This is called during Layout::finalize for
  // allocated sections.
  void
  set_address_and_file_offset(uint64_t addr, off_t off)
  {
    this->set_address(addr);
    this->set_file_offset(off);
    this->finalize_data_size();
  }

  // Set the address.
  void
  set_address(uint64_t addr)
  {
    gold_assert(!this->is_address_valid_);
    this->address_ = addr;
    this->is_address_valid_ = true;
  }

  // Set the file offset.
  void
  set_file_offset(off_t off)
  {
    gold_assert(!this->is_offset_valid_);
    this->offset_ = off;
    this->is_offset_valid_ = true;
  }

  // Update the data size without finalizing it.
  void
  pre_finalize_data_size()
  {
    if (!this->is_data_size_valid_)
      {
	// Tell the child class to update the data size.
	this->update_data_size();
      }
  }

  // Finalize the data size.
  void
  finalize_data_size()
  {
    if (!this->is_data_size_valid_)
      {
	// Tell the child class to set the data size.
	this->set_final_data_size();
	gold_assert(this->is_data_size_valid_);
      }
  }

  // Set the TLS offset.  Called only for SHT_TLS sections.
  void
  set_tls_offset(uint64_t tls_base)
  { this->do_set_tls_offset(tls_base); }

  // Return the TLS offset, relative to the base of the TLS segment.
  // Valid only for SHT_TLS sections.
  uint64_t
  tls_offset() const
  { return this->do_tls_offset(); }

  // Write the data to the output file.  This is called after
  // Layout::finalize is complete.
  void
  write(Output_file* file)
  { this->do_write(file); }

  // This is called by Layout::finalize to note that the sizes of
  // allocated sections must now be fixed.
  static void
  layout_complete()
  { Output_data::allocated_sizes_are_fixed = true; }

  // Used to check that layout has been done.
  static bool
  is_layout_complete()
  { return Output_data::allocated_sizes_are_fixed; }

  // Note that a dynamic reloc has been applied to this data.
  void
  add_dynamic_reloc()
  { this->has_dynamic_reloc_ = true; }

  // Return whether a dynamic reloc has been applied.
  bool
  has_dynamic_reloc() const
  { return this->has_dynamic_reloc_; }

  // Whether the address is valid.
  bool
  is_address_valid() const
  { return this->is_address_valid_; }

  // Whether the file offset is valid.
  bool
  is_offset_valid() const
  { return this->is_offset_valid_; }

  // Whether the data size is valid.
  bool
  is_data_size_valid() const
  { return this->is_data_size_valid_; }

  // Print information to the map file.
  void
  print_to_mapfile(Mapfile* mapfile) const
  { return this->do_print_to_mapfile(mapfile); }

 protected:
  // Functions that child classes may or in some cases must implement.

  // Write the data to the output file.
  virtual void
  do_write(Output_file*) = 0;

  // Return the required alignment.
  virtual uint64_t
  do_addralign() const = 0;

  // Return whether this has a load address.
  virtual bool
  do_has_load_address() const
  { return false; }

  // Return the load address.
  virtual uint64_t
  do_load_address() const
  { gold_unreachable(); }

  // Return whether this is an Output_section.
  virtual bool
  do_is_section() const
  { return false; }

  // Return whether this is an Output_section of the specified type.
  // This only needs to be implement by Output_section.
  virtual bool
  do_is_section_type(elfcpp::Elf_Word) const
  { return false; }

  // Return whether this is an Output_section with the specific flag
  // set.  This only needs to be implemented by Output_section.
  virtual bool
  do_is_section_flag_set(elfcpp::Elf_Xword) const
  { return false; }

  // Return the output section, if there is one.
  virtual Output_section*
  do_output_section()
  { return NULL; }

  virtual const Output_section*
  do_output_section() const
  { return NULL; }

  // Return the output section index, if there is an output section.
  virtual unsigned int
  do_out_shndx() const
  { gold_unreachable(); }

  // Set the output section index, if this is an output section.
  virtual void
  do_set_out_shndx(unsigned int)
  { gold_unreachable(); }

  // This is a hook for derived classes to set the preliminary data size.
  // This is called by pre_finalize_data_size, normally called during
  // Layout::finalize, before the section address is set, and is used
  // during an incremental update, when we need to know the size of a
  // section before allocating space in the output file.  For classes
  // where the current data size is up to date, this default version of
  // the method can be inherited.
  virtual void
  update_data_size()
  { }

  // This is a hook for derived classes to set the data size.  This is
  // called by finalize_data_size, normally called during
  // Layout::finalize, when the section address is set.
  virtual void
  set_final_data_size()
  { gold_unreachable(); }

  // A hook for resetting the address and file offset.
  virtual void
  do_reset_address_and_file_offset()
  { }

  // Return true if address and file offset already have reset values. In
  // other words, calling reset_address_and_file_offset will not change them.
  // A child class overriding do_reset_address_and_file_offset may need to
  // also override this.
  virtual bool
  do_address_and_file_offset_have_reset_values() const
  { return !this->is_address_valid_ && !this->is_offset_valid_; }

  // Set the TLS offset.  Called only for SHT_TLS sections.
  virtual void
  do_set_tls_offset(uint64_t)
  { gold_unreachable(); }

  // Return the TLS offset, relative to the base of the TLS segment.
  // Valid only for SHT_TLS sections.
  virtual uint64_t
  do_tls_offset() const
  { gold_unreachable(); }

  // Print to the map file.  This only needs to be implemented by
  // classes which may appear in a PT_LOAD segment.
  virtual void
  do_print_to_mapfile(Mapfile*) const
  { gold_unreachable(); }

  // Functions that child classes may call.

  // Reset the address.  The Output_section class needs this when an
  // SHF_ALLOC input section is added to an output section which was
  // formerly not SHF_ALLOC.
  void
  mark_address_invalid()
  { this->is_address_valid_ = false; }

  // Set the size of the data.
  void
  set_data_size(off_t data_size)
  {
    gold_assert(!this->is_data_size_valid_
		&& !this->is_data_size_fixed_);
    this->data_size_ = data_size;
    this->is_data_size_valid_ = true;
  }

  // Fix the data size.  Once it is fixed, it cannot be changed
  // and the data size remains always valid.
  void
  fix_data_size()
  {
    gold_assert(this->is_data_size_valid_);
    this->is_data_size_fixed_ = true;
  }

  // Get the current data size--this is for the convenience of
  // sections which build up their size over time.
  off_t
  current_data_size_for_child() const
  { return this->data_size_; }

  // Set the current data size--this is for the convenience of
  // sections which build up their size over time.
  void
  set_current_data_size_for_child(off_t data_size)
  {
    gold_assert(!this->is_data_size_valid_);
    this->data_size_ = data_size;
  }

  // Return default alignment for the target size.
  static uint64_t
  default_alignment();

  // Return default alignment for a specified size--32 or 64.
  static uint64_t
  default_alignment_for_size(int size);

 private:
  Output_data(const Output_data&);
  Output_data& operator=(const Output_data&);

  // This is used for verification, to make sure that we don't try to
  // change any sizes of allocated sections after we set the section
  // addresses.
  static bool allocated_sizes_are_fixed;

  // Memory address in output file.
  uint64_t address_;
  // Size of data in output file.
  off_t data_size_;
  // File offset of contents in output file.
  off_t offset_;
  // Whether address_ is valid.
  bool is_address_valid_ : 1;
  // Whether data_size_ is valid.
  bool is_data_size_valid_ : 1;
  // Whether offset_ is valid.
  bool is_offset_valid_ : 1;
  // Whether data size is fixed.
  bool is_data_size_fixed_ : 1;
  // Whether any dynamic relocs have been applied to this section.
  bool has_dynamic_reloc_ : 1;
};

// Output the section headers.

class Output_section_headers : public Output_data
{
 public:
  Output_section_headers(const Layout*,
			 const Layout::Segment_list*,
			 const Layout::Section_list*,
			 const Layout::Section_list*,
			 const Stringpool*,
			 const Output_section*);

 protected:
  // Write the data to the file.
  void
  do_write(Output_file*);

  // Return the required alignment.
  uint64_t
  do_addralign() const
  { return Output_data::default_alignment(); }

  // Write to a map file.
  void
  do_print_to_mapfile(Mapfile* mapfile) const
  { mapfile->print_output_data(this, _("** section headers")); }

  // Update the data size.
  void
  update_data_size()
  { this->set_data_size(this->do_size()); }

  // Set final data size.
  void
  set_final_data_size()
  { this->set_data_size(this->do_size()); }

 private:
  // Write the data to the file with the right size and endianness.
  template<int size, bool big_endian>
  void
  do_sized_write(Output_file*);

  // Compute data size.
  off_t
  do_size() const;

  const Layout* layout_;
  const Layout::Segment_list* segment_list_;
  const Layout::Section_list* section_list_;
  const Layout::Section_list* unattached_section_list_;
  const Stringpool* secnamepool_;
  const Output_section* shstrtab_section_;
};

// Output the segment headers.

class Output_segment_headers : public Output_data
{
 public:
  Output_segment_headers(const Layout::Segment_list& segment_list);

 protected:
  // Write the data to the file.
  void
  do_write(Output_file*);

  // Return the required alignment.
  uint64_t
  do_addralign() const
  { return Output_data::default_alignment(); }

  // Write to a map file.
  void
  do_print_to_mapfile(Mapfile* mapfile) const
  { mapfile->print_output_data(this, _("** segment headers")); }

  // Set final data size.
  void
  set_final_data_size()
  { this->set_data_size(this->do_size()); }

 private:
  // Write the data to the file with the right size and endianness.
  template<int size, bool big_endian>
  void
  do_sized_write(Output_file*);

  // Compute the current size.
  off_t
  do_size() const;

  const Layout::Segment_list& segment_list_;
};

// Output the ELF file header.

class Output_file_header : public Output_data
{
 public:
  Output_file_header(Target*,
		     const Symbol_table*,
		     const Output_segment_headers*);

  // Add information about the section headers.  We lay out the ELF
  // file header before we create the section headers.
  void set_section_info(const Output_section_headers*,
			const Output_section* shstrtab);

 protected:
  // Write the data to the file.
  void
  do_write(Output_file*);

  // Return the required alignment.
  uint64_t
  do_addralign() const
  { return Output_data::default_alignment(); }

  // Write to a map file.
  void
  do_print_to_mapfile(Mapfile* mapfile) const
  { mapfile->print_output_data(this, _("** file header")); }

  // Set final data size.
  void
  set_final_data_size(void)
  { this->set_data_size(this->do_size()); }

 private:
  // Write the data to the file with the right size and endianness.
  template<int size, bool big_endian>
  void
  do_sized_write(Output_file*);

  // Return the value to use for the entry address.
  template<int size>
  typename elfcpp::Elf_types<size>::Elf_Addr
  entry();

  // Compute the current data size.
  off_t
  do_size() const;

  Target* target_;
  const Symbol_table* symtab_;
  const Output_segment_headers* segment_header_;
  const Output_section_headers* section_header_;
  const Output_section* shstrtab_;
};

// Output sections are mainly comprised of input sections.  However,
// there are cases where we have data to write out which is not in an
// input section.  Output_section_data is used in such cases.  This is
// an abstract base class.

class Output_section_data : public Output_data
{
 public:
  Output_section_data(off_t data_size, uint64_t addralign,
		      bool is_data_size_fixed)
    : Output_data(), output_section_(NULL), addralign_(addralign)
  {
    this->set_data_size(data_size);
    if (is_data_size_fixed)
      this->fix_data_size();
  }

  Output_section_data(uint64_t addralign)
    : Output_data(), output_section_(NULL), addralign_(addralign)
  { }

  // Return the output section.
  Output_section*
  output_section()
  { return this->output_section_; }

  const Output_section*
  output_section() const
  { return this->output_section_; }

  // Record the output section.
  void
  set_output_section(Output_section* os);

  // Add an input section, for SHF_MERGE sections.  This returns true
  // if the section was handled.
  bool
  add_input_section(Relobj* object, unsigned int shndx)
  { return this->do_add_input_section(object, shndx); }

  // Given an input OBJECT, an input section index SHNDX within that
  // object, and an OFFSET relative to the start of that input
  // section, return whether or not the corresponding offset within
  // the output section is known.  If this function returns true, it
  // sets *POUTPUT to the output offset.  The value -1 indicates that
  // this input offset is being discarded.
  bool
  output_offset(const Relobj* object, unsigned int shndx,
		section_offset_type offset,
		section_offset_type* poutput) const
  { return this->do_output_offset(object, shndx, offset, poutput); }

  // Write the contents to a buffer.  This is used for sections which
  // require postprocessing, such as compression.
  void
  write_to_buffer(unsigned char* buffer)
  { this->do_write_to_buffer(buffer); }

  // Print merge stats to stderr.  This should only be called for
  // SHF_MERGE sections.
  void
  print_merge_stats(const char* section_name)
  { this->do_print_merge_stats(section_name); }

 protected:
  // The child class must implement do_write.

  // The child class may implement specific adjustments to the output
  // section.
  virtual void
  do_adjust_output_section(Output_section*)
  { }

  // May be implemented by child class.  Return true if the section
  // was handled.
  virtual bool
  do_add_input_section(Relobj*, unsigned int)
  { gold_unreachable(); }

  // The child class may implement output_offset.
  virtual bool
  do_output_offset(const Relobj*, unsigned int, section_offset_type,
		   section_offset_type*) const
  { return false; }

  // The child class may implement write_to_buffer.  Most child
  // classes can not appear in a compressed section, and they do not
  // implement this.
  virtual void
  do_write_to_buffer(unsigned char*)
  { gold_unreachable(); }

  // Print merge statistics.
  virtual void
  do_print_merge_stats(const char*)
  { gold_unreachable(); }

  // Return the required alignment.
  uint64_t
  do_addralign() const
  { return this->addralign_; }

  // Return the output section.
  Output_section*
  do_output_section()
  { return this->output_section_; }

  const Output_section*
  do_output_section() const
  { return this->output_section_; }

  // Return the section index of the output section.
  unsigned int
  do_out_shndx() const;

  // Set the alignment.
  void
  set_addralign(uint64_t addralign);

 private:
  // The output section for this section.
  Output_section* output_section_;
  // The required alignment.
  uint64_t addralign_;
};

// Some Output_section_data classes build up their data step by step,
// rather than all at once.  This class provides an interface for
// them.

class Output_section_data_build : public Output_section_data
{
 public:
  Output_section_data_build(uint64_t addralign)
    : Output_section_data(addralign)
  { }

  Output_section_data_build(off_t data_size, uint64_t addralign)
    : Output_section_data(data_size, addralign, false)
  { }

  // Set the current data size.
  void
  set_current_data_size(off_t data_size)
  { this->set_current_data_size_for_child(data_size); }

 protected:
  // Set the final data size.
  virtual void
  set_final_data_size()
  { this->set_data_size(this->current_data_size_for_child()); }
};

// A simple case of Output_data in which we have constant data to
// output.

class Output_data_const : public Output_section_data
{
 public:
  Output_data_const(const std::string& data, uint64_t addralign)
    : Output_section_data(data.size(), addralign, true), data_(data)
  { }

  Output_data_const(const char* p, off_t len, uint64_t addralign)
    : Output_section_data(len, addralign, true), data_(p, len)
  { }

  Output_data_const(const unsigned char* p, off_t len, uint64_t addralign)
    : Output_section_data(len, addralign, true),
      data_(reinterpret_cast<const char*>(p), len)
  { }

 protected:
  // Write the data to the output file.
  void
  do_write(Output_file*);

  // Write the data to a buffer.
  void
  do_write_to_buffer(unsigned char* buffer)
  { memcpy(buffer, this->data_.data(), this->data_.size()); }

  // Write to a map file.
  void
  do_print_to_mapfile(Mapfile* mapfile) const
  { mapfile->print_output_data(this, _("** fill")); }

 private:
  std::string data_;
};

// Another version of Output_data with constant data, in which the
// buffer is allocated by the caller.

class Output_data_const_buffer : public Output_section_data
{
 public:
  Output_data_const_buffer(const unsigned char* p, off_t len,
			   uint64_t addralign, const char* map_name)
    : Output_section_data(len, addralign, true),
      p_(p), map_name_(map_name)
  { }

 protected:
  // Write the data the output file.
  void
  do_write(Output_file*);

  // Write the data to a buffer.
  void
  do_write_to_buffer(unsigned char* buffer)
  { memcpy(buffer, this->p_, this->data_size()); }

  // Write to a map file.
  void
  do_print_to_mapfile(Mapfile* mapfile) const
  { mapfile->print_output_data(this, _(this->map_name_)); }

 private:
  // The data to output.
  const unsigned char* p_;
  // Name to use in a map file.  Maps are a rarely used feature, but
  // the space usage is minor as aren't very many of these objects.
  const char* map_name_;
};

// A place holder for a fixed amount of data written out via some
// other mechanism.

class Output_data_fixed_space : public Output_section_data
{
 public:
  Output_data_fixed_space(off_t data_size, uint64_t addralign,
			  const char* map_name)
    : Output_section_data(data_size, addralign, true),
      map_name_(map_name)
  { }

 protected:
  // Write out the data--the actual data must be written out
  // elsewhere.
  void
  do_write(Output_file*)
  { }

  // Write to a map file.
  void
  do_print_to_mapfile(Mapfile* mapfile) const
  { mapfile->print_output_data(this, _(this->map_name_)); }

 private:
  // Name to use in a map file.  Maps are a rarely used feature, but
  // the space usage is minor as aren't very many of these objects.
  const char* map_name_;
};

// A place holder for variable sized data written out via some other
// mechanism.

class Output_data_space : public Output_section_data_build
{
 public:
  explicit Output_data_space(uint64_t addralign, const char* map_name)
    : Output_section_data_build(addralign),
      map_name_(map_name)
  { }

  explicit Output_data_space(off_t data_size, uint64_t addralign,
			     const char* map_name)
    : Output_section_data_build(data_size, addralign),
      map_name_(map_name)
  { }

  // Set the alignment.
  void
  set_space_alignment(uint64_t align)
  { this->set_addralign(align); }

 protected:
  // Write out the data--the actual data must be written out
  // elsewhere.
  void
  do_write(Output_file*)
  { }

  // Write to a map file.
  void
  do_print_to_mapfile(Mapfile* mapfile) const
  { mapfile->print_output_data(this, _(this->map_name_)); }

 private:
  // Name to use in a map file.  Maps are a rarely used feature, but
  // the space usage is minor as aren't very many of these objects.
  const char* map_name_;
};

// Fill fixed space with zeroes.  This is just like
// Output_data_fixed_space, except that the map name is known.

class Output_data_zero_fill : public Output_section_data
{
 public:
  Output_data_zero_fill(off_t data_size, uint64_t addralign)
    : Output_section_data(data_size, addralign, true)
  { }

 protected:
  // There is no data to write out.
  void
  do_write(Output_file*)
  { }

  // Write to a map file.
  void
  do_print_to_mapfile(Mapfile* mapfile) const
  { mapfile->print_output_data(this, "** zero fill"); }
};

// A string table which goes into an output section.

class Output_data_strtab : public Output_section_data
{
 public:
  Output_data_strtab(Stringpool* strtab)
    : Output_section_data(1), strtab_(strtab)
  { }

 protected:
  // This is called to update the section size prior to assigning
  // the address and file offset.
  void
  update_data_size()
  { this->set_final_data_size(); }

  // This is called to set the address and file offset.  Here we make
  // sure that the Stringpool is finalized.
  void
  set_final_data_size();

  // Write out the data.
  void
  do_write(Output_file*);

  // Write the data to a buffer.
  void
  do_write_to_buffer(unsigned char* buffer)
  { this->strtab_->write_to_buffer(buffer, this->data_size()); }

  // Write to a map file.
  void
  do_print_to_mapfile(Mapfile* mapfile) const
  { mapfile->print_output_data(this, _("** string table")); }

 private:
  Stringpool* strtab_;
};

// This POD class is used to represent a single reloc in the output
// file.  This could be a private class within Output_data_reloc, but
// the templatization is complex enough that I broke it out into a
// separate class.  The class is templatized on either elfcpp::SHT_REL
// or elfcpp::SHT_RELA, and also on whether this is a dynamic
// relocation or an ordinary relocation.

// A relocation can be against a global symbol, a local symbol, a
// local section symbol, an output section, or the undefined symbol at
// index 0.  We represent the latter by using a NULL global symbol.

template<int sh_type, bool dynamic, int size, bool big_endian>
class Output_reloc;

template<bool dynamic, int size, bool big_endian>
class Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>
{
 public:
  typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
  typedef typename elfcpp::Elf_types<size>::Elf_Addr Addend;

  static const Address invalid_address = static_cast<Address>(0) - 1;

  // An uninitialized entry.  We need this because we want to put
  // instances of this class into an STL container.
  Output_reloc()
    : local_sym_index_(INVALID_CODE)
  { }

  // We have a bunch of different constructors.  They come in pairs
  // depending on how the address of the relocation is specified.  It
  // can either be an offset in an Output_data or an offset in an
  // input section.

  // A reloc against a global symbol.

  Output_reloc(Symbol* gsym, unsigned int type, Output_data* od,
	       Address address, bool is_relative, bool is_symbolless,
	       bool use_plt_offset);

  Output_reloc(Symbol* gsym, unsigned int type,
	       Sized_relobj<size, big_endian>* relobj,
	       unsigned int shndx, Address address, bool is_relative,
	       bool is_symbolless, bool use_plt_offset);

  // A reloc against a local symbol or local section symbol.

  Output_reloc(Sized_relobj<size, big_endian>* relobj,
	       unsigned int local_sym_index, unsigned int type,
	       Output_data* od, Address address, bool is_relative,
	       bool is_symbolless, bool is_section_symbol,
	       bool use_plt_offset);

  Output_reloc(Sized_relobj<size, big_endian>* relobj,
	       unsigned int local_sym_index, unsigned int type,
	       unsigned int shndx, Address address, bool is_relative,
	       bool is_symbolless, bool is_section_symbol,
	       bool use_plt_offset);

  // A reloc against the STT_SECTION symbol of an output section.

  Output_reloc(Output_section* os, unsigned int type, Output_data* od,
	       Address address, bool is_relative);

  Output_reloc(Output_section* os, unsigned int type,
	       Sized_relobj<size, big_endian>* relobj, unsigned int shndx,
	       Address address, bool is_relative);

  // An absolute or relative relocation with no symbol.

  Output_reloc(unsigned int type, Output_data* od, Address address,
	       bool is_relative);

  Output_reloc(unsigned int type, Sized_relobj<size, big_endian>* relobj,
	       unsigned int shndx, Address address, bool is_relative);

  // A target specific relocation.  The target will be called to get
  // the symbol index, passing ARG.  The type and offset will be set
  // as for other relocation types.

  Output_reloc(unsigned int type, void* arg, Output_data* od,
	       Address address);

  Output_reloc(unsigned int type, void* arg,
	       Sized_relobj<size, big_endian>* relobj,
	       unsigned int shndx, Address address);

  // Return the reloc type.
  unsigned int
  type() const
  { return this->type_; }

  // Return whether this is a RELATIVE relocation.
  bool
  is_relative() const
  { return this->is_relative_; }

  // Return whether this is a relocation which should not use
  // a symbol, but which obtains its addend from a symbol.
  bool
  is_symbolless() const
  { return this->is_symbolless_; }

  // Return whether this is against a local section symbol.
  bool
  is_local_section_symbol() const
  {
    return (this->local_sym_index_ != GSYM_CODE
	    && this->local_sym_index_ != SECTION_CODE
	    && this->local_sym_index_ != INVALID_CODE
	    && this->local_sym_index_ != TARGET_CODE
	    && this->is_section_symbol_);
  }

  // Return whether this is a target specific relocation.
  bool
  is_target_specific() const
  { return this->local_sym_index_ == TARGET_CODE; }

  // Return the argument to pass to the target for a target specific
  // relocation.
  void*
  target_arg() const
  {
    gold_assert(this->local_sym_index_ == TARGET_CODE);
    return this->u1_.arg;
  }

  // For a local section symbol, return the offset of the input
  // section within the output section.  ADDEND is the addend being
  // applied to the input section.
  Address
  local_section_offset(Addend addend) const;

  // Get the value of the symbol referred to by a Rel relocation when
  // we are adding the given ADDEND.
  Address
  symbol_value(Addend addend) const;

  // If this relocation is against an input section, return the
  // relocatable object containing the input section.
  Sized_relobj<size, big_endian>*
  get_relobj() const
  {
    if (this->shndx_ == INVALID_CODE)
      return NULL;
    return this->u2_.relobj;
  }

  // Write the reloc entry to an output view.
  void
  write(unsigned char* pov) const;

  // Write the offset and info fields to Write_rel.
  template<typename Write_rel>
  void write_rel(Write_rel*) const;

  // This is used when sorting dynamic relocs.  Return -1 to sort this
  // reloc before R2, 0 to sort the same as R2, 1 to sort after R2.
  int
  compare(const Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>& r2)
    const;

  // Return whether this reloc should be sorted before the argument
  // when sorting dynamic relocs.
  bool
  sort_before(const Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>&
	      r2) const
  { return this->compare(r2) < 0; }

  // Return the symbol index.
  unsigned int
  get_symbol_index() const;

  // Return the output address.
  Address
  get_address() const;

 private:
  // Record that we need a dynamic symbol index.
  void
  set_needs_dynsym_index();

  // Codes for local_sym_index_.
  enum
  {
    // Global symbol.
    GSYM_CODE = -1U,
    // Output section.
    SECTION_CODE = -2U,
    // Target specific.
    TARGET_CODE = -3U,
    // Invalid uninitialized entry.
    INVALID_CODE = -4U
  };

  union
  {
    // For a local symbol or local section symbol
    // (this->local_sym_index_ >= 0), the object.  We will never
    // generate a relocation against a local symbol in a dynamic
    // object; that doesn't make sense.  And our callers will always
    // be templatized, so we use Sized_relobj here.
    Sized_relobj<size, big_endian>* relobj;
    // For a global symbol (this->local_sym_index_ == GSYM_CODE, the
    // symbol.  If this is NULL, it indicates a relocation against the
    // undefined 0 symbol.
    Symbol* gsym;
    // For a relocation against an output section
    // (this->local_sym_index_ == SECTION_CODE), the output section.
    Output_section* os;
    // For a target specific relocation, an argument to pass to the
    // target.
    void* arg;
  } u1_;
  union
  {
    // If this->shndx_ is not INVALID CODE, the object which holds the
    // input section being used to specify the reloc address.
    Sized_relobj<size, big_endian>* relobj;
    // If this->shndx_ is INVALID_CODE, the output data being used to
    // specify the reloc address.  This may be NULL if the reloc
    // address is absolute.
    Output_data* od;
  } u2_;
  // The address offset within the input section or the Output_data.
  Address address_;
  // This is GSYM_CODE for a global symbol, or SECTION_CODE for a
  // relocation against an output section, or TARGET_CODE for a target
  // specific relocation, or INVALID_CODE for an uninitialized value.
  // Otherwise, for a local symbol (this->is_section_symbol_ is
  // false), the local symbol index.  For a local section symbol
  // (this->is_section_symbol_ is true), the section index in the
  // input file.
  unsigned int local_sym_index_;
  // The reloc type--a processor specific code.
  unsigned int type_ : 28;
  // True if the relocation is a RELATIVE relocation.
  bool is_relative_ : 1;
  // True if the relocation is one which should not use
  // a symbol, but which obtains its addend from a symbol.
  bool is_symbolless_ : 1;
  // True if the relocation is against a section symbol.
  bool is_section_symbol_ : 1;
  // True if the addend should be the PLT offset.
  // (Used only for RELA, but stored here for space.)
  bool use_plt_offset_ : 1;
  // If the reloc address is an input section in an object, the
  // section index.  This is INVALID_CODE if the reloc address is
  // specified in some other way.
  unsigned int shndx_;
};

// The SHT_RELA version of Output_reloc<>.  This is just derived from
// the SHT_REL version of Output_reloc, but it adds an addend.

template<bool dynamic, int size, bool big_endian>
class Output_reloc<elfcpp::SHT_RELA, dynamic, size, big_endian>
{
 public:
  typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
  typedef typename elfcpp::Elf_types<size>::Elf_Addr Addend;

  // An uninitialized entry.
  Output_reloc()
    : rel_()
  { }

  // A reloc against a global symbol.

  Output_reloc(Symbol* gsym, unsigned int type, Output_data* od,
	       Address address, Addend addend, bool is_relative,
	       bool is_symbolless, bool use_plt_offset)
    : rel_(gsym, type, od, address, is_relative, is_symbolless,
	   use_plt_offset),
      addend_(addend)
  { }

  Output_reloc(Symbol* gsym, unsigned int type,
	       Sized_relobj<size, big_endian>* relobj,
	       unsigned int shndx, Address address, Addend addend,
	       bool is_relative, bool is_symbolless, bool use_plt_offset)
    : rel_(gsym, type, relobj, shndx, address, is_relative,
	   is_symbolless, use_plt_offset), addend_(addend)
  { }

  // A reloc against a local symbol.

  Output_reloc(Sized_relobj<size, big_endian>* relobj,
	       unsigned int local_sym_index, unsigned int type,
	       Output_data* od, Address address,
	       Addend addend, bool is_relative,
	       bool is_symbolless, bool is_section_symbol,
	       bool use_plt_offset)
    : rel_(relobj, local_sym_index, type, od, address, is_relative,
	   is_symbolless, is_section_symbol, use_plt_offset),
      addend_(addend)
  { }

  Output_reloc(Sized_relobj<size, big_endian>* relobj,
	       unsigned int local_sym_index, unsigned int type,
	       unsigned int shndx, Address address,
	       Addend addend, bool is_relative,
	       bool is_symbolless, bool is_section_symbol,
	       bool use_plt_offset)
    : rel_(relobj, local_sym_index, type, shndx, address, is_relative,
	   is_symbolless, is_section_symbol, use_plt_offset),
      addend_(addend)
  { }

  // A reloc against the STT_SECTION symbol of an output section.

  Output_reloc(Output_section* os, unsigned int type, Output_data* od,
	       Address address, Addend addend, bool is_relative)
    : rel_(os, type, od, address, is_relative), addend_(addend)
  { }

  Output_reloc(Output_section* os, unsigned int type,
	       Sized_relobj<size, big_endian>* relobj,
	       unsigned int shndx, Address address, Addend addend,
	       bool is_relative)
    : rel_(os, type, relobj, shndx, address, is_relative), addend_(addend)
  { }

  // An absolute or relative relocation with no symbol.

  Output_reloc(unsigned int type, Output_data* od, Address address,
	       Addend addend, bool is_relative)
    : rel_(type, od, address, is_relative), addend_(addend)
  { }

  Output_reloc(unsigned int type, Sized_relobj<size, big_endian>* relobj,
	       unsigned int shndx, Address address, Addend addend,
	       bool is_relative)
    : rel_(type, relobj, shndx, address, is_relative), addend_(addend)
  { }

  // A target specific relocation.  The target will be called to get
  // the symbol index and the addend, passing ARG.  The type and
  // offset will be set as for other relocation types.

  Output_reloc(unsigned int type, void* arg, Output_data* od,
	       Address address, Addend addend)
    : rel_(type, arg, od, address), addend_(addend)
  { }

  Output_reloc(unsigned int type, void* arg,
	       Sized_relobj<size, big_endian>* relobj,
	       unsigned int shndx, Address address, Addend addend)
    : rel_(type, arg, relobj, shndx, address), addend_(addend)
  { }

  // Return whether this is a RELATIVE relocation.
  bool
  is_relative() const
  { return this->rel_.is_relative(); }

  // Return whether this is a relocation which should not use
  // a symbol, but which obtains its addend from a symbol.
  bool
  is_symbolless() const
  { return this->rel_.is_symbolless(); }

  // If this relocation is against an input section, return the
  // relocatable object containing the input section.
  Sized_relobj<size, big_endian>*
  get_relobj() const
  { return this->rel_.get_relobj(); }

  // Write the reloc entry to an output view.
  void
  write(unsigned char* pov) const;

  // Return whether this reloc should be sorted before the argument
  // when sorting dynamic relocs.
  bool
  sort_before(const Output_reloc<elfcpp::SHT_RELA, dynamic, size, big_endian>&
	      r2) const
  {
    int i = this->rel_.compare(r2.rel_);
    if (i < 0)
      return true;
    else if (i > 0)
      return false;
    else
      return this->addend_ < r2.addend_;
  }

 private:
  // The basic reloc.
  Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian> rel_;
  // The addend.
  Addend addend_;
};

// Output_data_reloc_generic is a non-template base class for
// Output_data_reloc_base.  This gives the generic code a way to hold
// a pointer to a reloc section.

class Output_data_reloc_generic : public Output_section_data_build
{
 public:
  Output_data_reloc_generic(int size, bool sort_relocs)
    : Output_section_data_build(Output_data::default_alignment_for_size(size)),
      relative_reloc_count_(0), sort_relocs_(sort_relocs)
  { }

  // Return the number of relative relocs in this section.
  size_t
  relative_reloc_count() const
  { return this->relative_reloc_count_; }

  // Whether we should sort the relocs.
  bool
  sort_relocs() const
  { return this->sort_relocs_; }

  // Add a reloc of type TYPE against the global symbol GSYM.  The
  // relocation applies to the data at offset ADDRESS within OD.
  virtual void
  add_global_generic(Symbol* gsym, unsigned int type, Output_data* od,
		     uint64_t address, uint64_t addend) = 0;

  // Add a reloc of type TYPE against the global symbol GSYM.  The
  // relocation applies to data at offset ADDRESS within section SHNDX
  // of object file RELOBJ.  OD is the associated output section.
  virtual void
  add_global_generic(Symbol* gsym, unsigned int type, Output_data* od,
		     Relobj* relobj, unsigned int shndx, uint64_t address,
		     uint64_t addend) = 0;

  // Add a reloc of type TYPE against the local symbol LOCAL_SYM_INDEX
  // in RELOBJ.  The relocation applies to the data at offset ADDRESS
  // within OD.
  virtual void
  add_local_generic(Relobj* relobj, unsigned int local_sym_index,
		    unsigned int type, Output_data* od, uint64_t address,
		    uint64_t addend) = 0;

  // Add a reloc of type TYPE against the local symbol LOCAL_SYM_INDEX
  // in RELOBJ.  The relocation applies to the data at offset ADDRESS
  // within section SHNDX of RELOBJ.  OD is the associated output
  // section.
  virtual void
  add_local_generic(Relobj* relobj, unsigned int local_sym_index,
		    unsigned int type, Output_data* od, unsigned int shndx,
		    uint64_t address, uint64_t addend) = 0;

  // Add a reloc of type TYPE against the STT_SECTION symbol of the
  // output section OS.  The relocation applies to the data at offset
  // ADDRESS within OD.
  virtual void
  add_output_section_generic(Output_section *os, unsigned int type,
			     Output_data* od, uint64_t address,
			     uint64_t addend) = 0;

  // Add a reloc of type TYPE against the STT_SECTION symbol of the
  // output section OS.  The relocation applies to the data at offset
  // ADDRESS within section SHNDX of RELOBJ.  OD is the associated
  // output section.
  virtual void
  add_output_section_generic(Output_section* os, unsigned int type,
			     Output_data* od, Relobj* relobj,
			     unsigned int shndx, uint64_t address,
			     uint64_t addend) = 0;

 protected:
  // Note that we've added another relative reloc.
  void
  bump_relative_reloc_count()
  { ++this->relative_reloc_count_; }

 private:
  // The number of relative relocs added to this section.  This is to
  // support DT_RELCOUNT.
  size_t relative_reloc_count_;
  // Whether to sort the relocations when writing them out, to make
  // the dynamic linker more efficient.
  bool sort_relocs_;
};

// Output_data_reloc is used to manage a section containing relocs.
// SH_TYPE is either elfcpp::SHT_REL or elfcpp::SHT_RELA.  DYNAMIC
// indicates whether this is a dynamic relocation or a normal
// relocation.  Output_data_reloc_base is a base class.
// Output_data_reloc is the real class, which we specialize based on
// the reloc type.

template<int sh_type, bool dynamic, int size, bool big_endian>
class Output_data_reloc_base : public Output_data_reloc_generic
{
 public:
  typedef Output_reloc<sh_type, dynamic, size, big_endian> Output_reloc_type;
  typedef typename Output_reloc_type::Address Address;
  static const int reloc_size =
    Reloc_types<sh_type, size, big_endian>::reloc_size;

  // Construct the section.
  Output_data_reloc_base(bool sort_relocs)
    : Output_data_reloc_generic(size, sort_relocs)
  { }

 protected:
  // Write out the data.
  void
  do_write(Output_file*);

  // Generic implementation of do_write, allowing a customized
  // class for writing the output relocation (e.g., for MIPS-64).
  template<class Output_reloc_writer>
  void
  do_write_generic(Output_file* of)
  {
    const off_t off = this->offset();
    const off_t oview_size = this->data_size();
    unsigned char* const oview = of->get_output_view(off, oview_size);

    if (this->sort_relocs())
      {
	gold_assert(dynamic);
	std::sort(this->relocs_.begin(), this->relocs_.end(),
		  Sort_relocs_comparison());
      }

    unsigned char* pov = oview;
    for (typename Relocs::const_iterator p = this->relocs_.begin();
	 p != this->relocs_.end();
	 ++p)
      {
	Output_reloc_writer::write(p, pov);
	pov += reloc_size;
      }

    gold_assert(pov - oview == oview_size);

    of->write_output_view(off, oview_size, oview);

    // We no longer need the relocation entries.
    this->relocs_.clear();
  }

  // Set the entry size and the link.
  void
  do_adjust_output_section(Output_section* os);

  // Write to a map file.
  void
  do_print_to_mapfile(Mapfile* mapfile) const
  {
    mapfile->print_output_data(this,
			       (dynamic
				? _("** dynamic relocs")
				: _("** relocs")));
  }

  // Add a relocation entry.
  void
  add(Output_data* od, const Output_reloc_type& reloc)
  {
    this->relocs_.push_back(reloc);
    this->set_current_data_size(this->relocs_.size() * reloc_size);
    if (dynamic)
      od->add_dynamic_reloc();
    if (reloc.is_relative())
      this->bump_relative_reloc_count();
    Sized_relobj<size, big_endian>* relobj = reloc.get_relobj();
    if (relobj != NULL)
      relobj->add_dyn_reloc(this->relocs_.size() - 1);
  }

 private:
  typedef std::vector<Output_reloc_type> Relocs;

  // The class used to sort the relocations.
  struct Sort_relocs_comparison
  {
    bool
    operator()(const Output_reloc_type& r1, const Output_reloc_type& r2) const
    { return r1.sort_before(r2); }
  };

  // The relocations in this section.
  Relocs relocs_;
};

// The class which callers actually create.

template<int sh_type, bool dynamic, int size, bool big_endian>
class Output_data_reloc;

// The SHT_REL version of Output_data_reloc.

template<bool dynamic, int size, bool big_endian>
class Output_data_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>
  : public Output_data_reloc_base<elfcpp::SHT_REL, dynamic, size, big_endian>
{
 private:
  typedef Output_data_reloc_base<elfcpp::SHT_REL, dynamic, size,
				 big_endian> Base;

 public:
  typedef typename Base::Output_reloc_type Output_reloc_type;
  typedef typename Output_reloc_type::Address Address;

  Output_data_reloc(bool sr)
    : Output_data_reloc_base<elfcpp::SHT_REL, dynamic, size, big_endian>(sr)
  { }

  // Add a reloc against a global symbol.

  void
  add_global(Symbol* gsym, unsigned int type, Output_data* od, Address address)
  {
    this->add(od, Output_reloc_type(gsym, type, od, address,
				    false, false, false));
  }

  void
  add_global(Symbol* gsym, unsigned int type, Output_data* od,
	     Sized_relobj<size, big_endian>* relobj,
	     unsigned int shndx, Address address)
  {
    this->add(od, Output_reloc_type(gsym, type, relobj, shndx, address,
				    false, false, false));
  }

  void
  add_global_generic(Symbol* gsym, unsigned int type, Output_data* od,
		     uint64_t address, uint64_t addend)
  {
    gold_assert(addend == 0);
    this->add(od, Output_reloc_type(gsym, type, od,
				    convert_types<Address, uint64_t>(address),
				    false, false, false));
  }

  void
  add_global_generic(Symbol* gsym, unsigned int type, Output_data* od,
		     Relobj* relobj, unsigned int shndx, uint64_t address,
		     uint64_t addend)
  {
    gold_assert(addend == 0);
    Sized_relobj<size, big_endian>* sized_relobj =
      static_cast<Sized_relobj<size, big_endian>*>(relobj);
    this->add(od, Output_reloc_type(gsym, type, sized_relobj, shndx,
				    convert_types<Address, uint64_t>(address),
				    false, false, false));
  }

  // Add a RELATIVE reloc against a global symbol.  The final relocation
  // will not reference the symbol.

  void
  add_global_relative(Symbol* gsym, unsigned int type, Output_data* od,
		      Address address)
  {
    this->add(od, Output_reloc_type(gsym, type, od, address, true, true,
				    false));
  }

  void
  add_global_relative(Symbol* gsym, unsigned int type, Output_data* od,
		      Sized_relobj<size, big_endian>* relobj,
		      unsigned int shndx, Address address)
  {
    this->add(od, Output_reloc_type(gsym, type, relobj, shndx, address,
				    true, true, false));
  }

  // Add a global relocation which does not use a symbol for the relocation,
  // but which gets its addend from a symbol.

  void
  add_symbolless_global_addend(Symbol* gsym, unsigned int type,
			       Output_data* od, Address address)
  {
    this->add(od, Output_reloc_type(gsym, type, od, address, false, true,
				    false));
  }

  void
  add_symbolless_global_addend(Symbol* gsym, unsigned int type,
			       Output_data* od,
			       Sized_relobj<size, big_endian>* relobj,
			       unsigned int shndx, Address address)
  {
    this->add(od, Output_reloc_type(gsym, type, relobj, shndx, address,
				    false, true, false));
  }

  // Add a reloc against a local symbol.

  void
  add_local(Sized_relobj<size, big_endian>* relobj,
	    unsigned int local_sym_index, unsigned int type,
	    Output_data* od, Address address)
  {
    this->add(od, Output_reloc_type(relobj, local_sym_index, type, od,
				    address, false, false, false, false));
  }

  void
  add_local(Sized_relobj<size, big_endian>* relobj,
	    unsigned int local_sym_index, unsigned int type,
	    Output_data* od, unsigned int shndx, Address address)
  {
    this->add(od, Output_reloc_type(relobj, local_sym_index, type, shndx,
				    address, false, false, false, false));
  }

  void
  add_local_generic(Relobj* relobj, unsigned int local_sym_index,
		    unsigned int type, Output_data* od, uint64_t address,
		    uint64_t addend)
  {
    gold_assert(addend == 0);
    Sized_relobj<size, big_endian>* sized_relobj =
      static_cast<Sized_relobj<size, big_endian> *>(relobj);
    this->add(od, Output_reloc_type(sized_relobj, local_sym_index, type, od,
				    convert_types<Address, uint64_t>(address),
				    false, false, false, false));
  }

  void
  add_local_generic(Relobj* relobj, unsigned int local_sym_index,
		    unsigned int type, Output_data* od, unsigned int shndx,
		    uint64_t address, uint64_t addend)
  {
    gold_assert(addend == 0);
    Sized_relobj<size, big_endian>* sized_relobj =
      static_cast<Sized_relobj<size, big_endian>*>(relobj);
    this->add(od, Output_reloc_type(sized_relobj, local_sym_index, type, shndx,
				    convert_types<Address, uint64_t>(address),
				    false, false, false, false));
  }

  // Add a RELATIVE reloc against a local symbol.

  void
  add_local_relative(Sized_relobj<size, big_endian>* relobj,
		     unsigned int local_sym_index, unsigned int type,
		     Output_data* od, Address address)
  {
    this->add(od, Output_reloc_type(relobj, local_sym_index, type, od,
				    address, true, true, false, false));
  }

  void
  add_local_relative(Sized_relobj<size, big_endian>* relobj,
		     unsigned int local_sym_index, unsigned int type,
		     Output_data* od, unsigned int shndx, Address address)
  {
    this->add(od, Output_reloc_type(relobj, local_sym_index, type, shndx,
				    address, true, true, false, false));
  }

  void
  add_local_relative(Sized_relobj<size, big_endian>* relobj,
		     unsigned int local_sym_index, unsigned int type,
		     Output_data* od, unsigned int shndx, Address address,
		     bool use_plt_offset)
  {
    this->add(od, Output_reloc_type(relobj, local_sym_index, type, shndx,
				    address, true, true, false,
				    use_plt_offset));
  }

  // Add a local relocation which does not use a symbol for the relocation,
  // but which gets its addend from a symbol.

  void
  add_symbolless_local_addend(Sized_relobj<size, big_endian>* relobj,
			      unsigned int local_sym_index, unsigned int type,
			      Output_data* od, Address address)
  {
    this->add(od, Output_reloc_type(relobj, local_sym_index, type, od,
				    address, false, true, false, false));
  }

  void
  add_symbolless_local_addend(Sized_relobj<size, big_endian>* relobj,
			      unsigned int local_sym_index, unsigned int type,
			      Output_data* od, unsigned int shndx,
			      Address address)
  {
    this->add(od, Output_reloc_type(relobj, local_sym_index, type, shndx,
				    address, false, true, false, false));
  }

  // Add a reloc against a local section symbol.  This will be
  // converted into a reloc against the STT_SECTION symbol of the
  // output section.

  void
  add_local_section(Sized_relobj<size, big_endian>* relobj,
		    unsigned int input_shndx, unsigned int type,
		    Output_data* od, Address address)
  {
    this->add(od, Output_reloc_type(relobj, input_shndx, type, od,
				    address, false, false, true, false));
  }

  void
  add_local_section(Sized_relobj<size, big_endian>* relobj,
		    unsigned int input_shndx, unsigned int type,
		    Output_data* od, unsigned int shndx, Address address)
  {
    this->add(od, Output_reloc_type(relobj, input_shndx, type, shndx,
				    address, false, false, true, false));
  }

  // A reloc against the STT_SECTION symbol of an output section.
  // OS is the Output_section that the relocation refers to; OD is
  // the Output_data object being relocated.

  void
  add_output_section(Output_section* os, unsigned int type,
		     Output_data* od, Address address)
  { this->add(od, Output_reloc_type(os, type, od, address, false)); }

  void
  add_output_section(Output_section* os, unsigned int type, Output_data* od,
		     Sized_relobj<size, big_endian>* relobj,
		     unsigned int shndx, Address address)
  { this->add(od, Output_reloc_type(os, type, relobj, shndx, address, false)); }

  void
  add_output_section_generic(Output_section* os, unsigned int type,
			     Output_data* od, uint64_t address,
			     uint64_t addend)
  {
    gold_assert(addend == 0);
    this->add(od, Output_reloc_type(os, type, od,
				    convert_types<Address, uint64_t>(address),
				    false));
  }

  void
  add_output_section_generic(Output_section* os, unsigned int type,
			     Output_data* od, Relobj* relobj,
			     unsigned int shndx, uint64_t address,
			     uint64_t addend)
  {
    gold_assert(addend == 0);
    Sized_relobj<size, big_endian>* sized_relobj =
      static_cast<Sized_relobj<size, big_endian>*>(relobj);
    this->add(od, Output_reloc_type(os, type, sized_relobj, shndx,
				    convert_types<Address, uint64_t>(address),
				    false));
  }

  // As above, but the reloc TYPE is relative

  void
  add_output_section_relative(Output_section* os, unsigned int type,
			      Output_data* od, Address address)
  { this->add(od, Output_reloc_type(os, type, od, address, true)); }

  void
  add_output_section_relative(Output_section* os, unsigned int type,
			      Output_data* od,
			      Sized_relobj<size, big_endian>* relobj,
			      unsigned int shndx, Address address)
  { this->add(od, Output_reloc_type(os, type, relobj, shndx, address, true)); }

  // Add an absolute relocation.

  void
  add_absolute(unsigned int type, Output_data* od, Address address)
  { this->add(od, Output_reloc_type(type, od, address, false)); }

  void
  add_absolute(unsigned int type, Output_data* od,
	       Sized_relobj<size, big_endian>* relobj,
	       unsigned int shndx, Address address)
  { this->add(od, Output_reloc_type(type, relobj, shndx, address, false)); }

  // Add a relative relocation

  void
  add_relative(unsigned int type, Output_data* od, Address address)
  { this->add(od, Output_reloc_type(type, od, address, true)); }

  void
  add_relative(unsigned int type, Output_data* od,
	       Sized_relobj<size, big_endian>* relobj,
	       unsigned int shndx, Address address)
  { this->add(od, Output_reloc_type(type, relobj, shndx, address, true)); }

  // Add a target specific relocation.  A target which calls this must
  // define the reloc_symbol_index and reloc_addend virtual functions.

  void
  add_target_specific(unsigned int type, void* arg, Output_data* od,
		      Address address)
  { this->add(od, Output_reloc_type(type, arg, od, address)); }

  void
  add_target_specific(unsigned int type, void* arg, Output_data* od,
		      Sized_relobj<size, big_endian>* relobj,
		      unsigned int shndx, Address address)
  { this->add(od, Output_reloc_type(type, arg, relobj, shndx, address)); }
};

// The SHT_RELA version of Output_data_reloc.

template<bool dynamic, int size, bool big_endian>
class Output_data_reloc<elfcpp::SHT_RELA, dynamic, size, big_endian>
  : public Output_data_reloc_base<elfcpp::SHT_RELA, dynamic, size, big_endian>
{
 private:
  typedef Output_data_reloc_base<elfcpp::SHT_RELA, dynamic, size,
				 big_endian> Base;

 public:
  typedef typename Base::Output_reloc_type Output_reloc_type;
  typedef typename Output_reloc_type::Address Address;
  typedef typename Output_reloc_type::Addend Addend;

  Output_data_reloc(bool sr)
    : Output_data_reloc_base<elfcpp::SHT_RELA, dynamic, size, big_endian>(sr)
  { }

  // Add a reloc against a global symbol.

  void
  add_global(Symbol* gsym, unsigned int type, Output_data* od,
	     Address address, Addend addend)
  {
    this->add(od, Output_reloc_type(gsym, type, od, address, addend,
				    false, false, false));
  }

  void
  add_global(Symbol* gsym, unsigned int type, Output_data* od,
	     Sized_relobj<size, big_endian>* relobj,
	     unsigned int shndx, Address address,
	     Addend addend)
  {
    this->add(od, Output_reloc_type(gsym, type, relobj, shndx, address,
				    addend, false, false, false));
  }

  void
  add_global_generic(Symbol* gsym, unsigned int type, Output_data* od,
		     uint64_t address, uint64_t addend)
  {
    this->add(od, Output_reloc_type(gsym, type, od,
				    convert_types<Address, uint64_t>(address),
				    convert_types<Addend, uint64_t>(addend),
				    false, false, false));
  }

  void
  add_global_generic(Symbol* gsym, unsigned int type, Output_data* od,
		     Relobj* relobj, unsigned int shndx, uint64_t address,
		     uint64_t addend)
  {
    Sized_relobj<size, big_endian>* sized_relobj =
      static_cast<Sized_relobj<size, big_endian>*>(relobj);
    this->add(od, Output_reloc_type(gsym, type, sized_relobj, shndx,
				    convert_types<Address, uint64_t>(address),
				    convert_types<Addend, uint64_t>(addend),
				    false, false, false));
  }

  // Add a RELATIVE reloc against a global symbol.  The final output
  // relocation will not reference the symbol, but we must keep the symbol
  // information long enough to set the addend of the relocation correctly
  // when it is written.

  void
  add_global_relative(Symbol* gsym, unsigned int type, Output_data* od,
		      Address address, Addend addend, bool use_plt_offset)
  {
    this->add(od, Output_reloc_type(gsym, type, od, address, addend, true,
				    true, use_plt_offset));
  }

  void
  add_global_relative(Symbol* gsym, unsigned int type, Output_data* od,
		      Sized_relobj<size, big_endian>* relobj,
		      unsigned int shndx, Address address, Addend addend,
		      bool use_plt_offset)
  {
    this->add(od, Output_reloc_type(gsym, type, relobj, shndx, address,
				    addend, true, true, use_plt_offset));
  }

  // Add a global relocation which does not use a symbol for the relocation,
  // but which gets its addend from a symbol.

  void
  add_symbolless_global_addend(Symbol* gsym, unsigned int type, Output_data* od,
			       Address address, Addend addend)
  {
    this->add(od, Output_reloc_type(gsym, type, od, address, addend,
				    false, true, false));
  }

  void
  add_symbolless_global_addend(Symbol* gsym, unsigned int type,
			       Output_data* od,
			       Sized_relobj<size, big_endian>* relobj,
			       unsigned int shndx, Address address,
			       Addend addend)
  {
    this->add(od, Output_reloc_type(gsym, type, relobj, shndx, address,
				    addend, false, true, false));
  }

  // Add a reloc against a local symbol.

  void
  add_local(Sized_relobj<size, big_endian>* relobj,
	    unsigned int local_sym_index, unsigned int type,
	    Output_data* od, Address address, Addend addend)
  {
    this->add(od, Output_reloc_type(relobj, local_sym_index, type, od, address,
				    addend, false, false, false, false));
  }

  void
  add_local(Sized_relobj<size, big_endian>* relobj,
	    unsigned int local_sym_index, unsigned int type,
	    Output_data* od, unsigned int shndx, Address address,
	    Addend addend)
  {
    this->add(od, Output_reloc_type(relobj, local_sym_index, type, shndx,
				    address, addend, false, false, false,
				    false));
  }

  void
  add_local_generic(Relobj* relobj, unsigned int local_sym_index,
		    unsigned int type, Output_data* od, uint64_t address,
		    uint64_t addend)
  {
    Sized_relobj<size, big_endian>* sized_relobj =
      static_cast<Sized_relobj<size, big_endian> *>(relobj);
    this->add(od, Output_reloc_type(sized_relobj, local_sym_index, type, od,
				    convert_types<Address, uint64_t>(address),
				    convert_types<Addend, uint64_t>(addend),
				    false, false, false, false));
  }

  void
  add_local_generic(Relobj* relobj, unsigned int local_sym_index,
		    unsigned int type, Output_data* od, unsigned int shndx,
		    uint64_t address, uint64_t addend)
  {
    Sized_relobj<size, big_endian>* sized_relobj =
      static_cast<Sized_relobj<size, big_endian>*>(relobj);
    this->add(od, Output_reloc_type(sized_relobj, local_sym_index, type, shndx,
				    convert_types<Address, uint64_t>(address),
				    convert_types<Addend, uint64_t>(addend),
				    false, false, false, false));
  }

  // Add a RELATIVE reloc against a local symbol.

  void
  add_local_relative(Sized_relobj<size, big_endian>* relobj,
		     unsigned int local_sym_index, unsigned int type,
		     Output_data* od, Address address, Addend addend,
		     bool use_plt_offset)
  {
    this->add(od, Output_reloc_type(relobj, local_sym_index, type, od, address,
				    addend, true, true, false,
				    use_plt_offset));
  }

  void
  add_local_relative(Sized_relobj<size, big_endian>* relobj,
		     unsigned int local_sym_index, unsigned int type,
		     Output_data* od, unsigned int shndx, Address address,
		     Addend addend, bool use_plt_offset)
  {
    this->add(od, Output_reloc_type(relobj, local_sym_index, type, shndx,
				    address, addend, true, true, false,
				    use_plt_offset));
  }

  // Add a local relocation which does not use a symbol for the relocation,
  // but which gets it's addend from a symbol.

  void
  add_symbolless_local_addend(Sized_relobj<size, big_endian>* relobj,
			      unsigned int local_sym_index, unsigned int type,
			      Output_data* od, Address address, Addend addend)
  {
    this->add(od, Output_reloc_type(relobj, local_sym_index, type, od, address,
				    addend, false, true, false, false));
  }

  void
  add_symbolless_local_addend(Sized_relobj<size, big_endian>* relobj,
			      unsigned int local_sym_index, unsigned int type,
			      Output_data* od, unsigned int shndx,
			      Address address, Addend addend)
  {
    this->add(od, Output_reloc_type(relobj, local_sym_index, type, shndx,
				    address, addend, false, true, false,
				    false));
  }

  // Add a reloc against a local section symbol.  This will be
  // converted into a reloc against the STT_SECTION symbol of the
  // output section.

  void
  add_local_section(Sized_relobj<size, big_endian>* relobj,
		    unsigned int input_shndx, unsigned int type,
		    Output_data* od, Address address, Addend addend)
  {
    this->add(od, Output_reloc_type(relobj, input_shndx, type, od, address,
				    addend, false, false, true, false));
  }

  void
  add_local_section(Sized_relobj<size, big_endian>* relobj,
		    unsigned int input_shndx, unsigned int type,
		    Output_data* od, unsigned int shndx, Address address,
		    Addend addend)
  {
    this->add(od, Output_reloc_type(relobj, input_shndx, type, shndx,
				    address, addend, false, false, true,
				    false));
  }

  // A reloc against the STT_SECTION symbol of an output section.

  void
  add_output_section(Output_section* os, unsigned int type, Output_data* od,
		     Address address, Addend addend)
  { this->add(od, Output_reloc_type(os, type, od, address, addend, false)); }

  void
  add_output_section(Output_section* os, unsigned int type, Output_data* od,
		     Sized_relobj<size, big_endian>* relobj,
		     unsigned int shndx, Address address, Addend addend)
  {
    this->add(od, Output_reloc_type(os, type, relobj, shndx, address,
				    addend, false));
  }

  void
  add_output_section_generic(Output_section* os, unsigned int type,
			     Output_data* od, uint64_t address,
			     uint64_t addend)
  {
    this->add(od, Output_reloc_type(os, type, od,
				    convert_types<Address, uint64_t>(address),
				    convert_types<Addend, uint64_t>(addend),
				    false));
  }

  void
  add_output_section_generic(Output_section* os, unsigned int type,
			     Output_data* od, Relobj* relobj,
			     unsigned int shndx, uint64_t address,
			     uint64_t addend)
  {
    Sized_relobj<size, big_endian>* sized_relobj =
      static_cast<Sized_relobj<size, big_endian>*>(relobj);
    this->add(od, Output_reloc_type(os, type, sized_relobj, shndx,
				    convert_types<Address, uint64_t>(address),
				    convert_types<Addend, uint64_t>(addend),
				    false));
  }

  // As above, but the reloc TYPE is relative

  void
  add_output_section_relative(Output_section* os, unsigned int type,
			      Output_data* od, Address address, Addend addend)
  { this->add(od, Output_reloc_type(os, type, od, address, addend, true)); }

  void
  add_output_section_relative(Output_section* os, unsigned int type,
			      Output_data* od,
			      Sized_relobj<size, big_endian>* relobj,
			      unsigned int shndx, Address address,
			      Addend addend)
  {
    this->add(od, Output_reloc_type(os, type, relobj, shndx,
				    address, addend, true));
  }

  // Add an absolute relocation.

  void
  add_absolute(unsigned int type, Output_data* od, Address address,
	       Addend addend)
  { this->add(od, Output_reloc_type(type, od, address, addend, false)); }

  void
  add_absolute(unsigned int type, Output_data* od,
	       Sized_relobj<size, big_endian>* relobj,
	       unsigned int shndx, Address address, Addend addend)
  {
    this->add(od, Output_reloc_type(type, relobj, shndx, address, addend,
				    false));
  }

  // Add a relative relocation

  void
  add_relative(unsigned int type, Output_data* od, Address address,
	       Addend addend)
  { this->add(od, Output_reloc_type(type, od, address, addend, true)); }

  void
  add_relative(unsigned int type, Output_data* od,
	       Sized_relobj<size, big_endian>* relobj,
	       unsigned int shndx, Address address, Addend addend)
  {
    this->add(od, Output_reloc_type(type, relobj, shndx, address, addend,
				    true));
  }

  // Add a target specific relocation.  A target which calls this must
  // define the reloc_symbol_index and reloc_addend virtual functions.

  void
  add_target_specific(unsigned int type, void* arg, Output_data* od,
		      Address address, Addend addend)
  { this->add(od, Output_reloc_type(type, arg, od, address, addend)); }

  void
  add_target_specific(unsigned int type, void* arg, Output_data* od,
		      Sized_relobj<size, big_endian>* relobj,
		      unsigned int shndx, Address address, Addend addend)
  {
    this->add(od, Output_reloc_type(type, arg, relobj, shndx, address,
				    addend));
  }
};

// Output_relocatable_relocs represents a relocation section in a
// relocatable link.  The actual data is written out in the target
// hook relocate_relocs.  This just saves space for it.

template<int sh_type, int size, bool big_endian>
class Output_relocatable_relocs : public Output_section_data
{
 public:
  Output_relocatable_relocs(Relocatable_relocs* rr)
    : Output_section_data(Output_data::default_alignment_for_size(size)),
      rr_(rr)
  { }

  void
  set_final_data_size();

  // Write out the data.  There is nothing to do here.
  void
  do_write(Output_file*)
  { }

  // Write to a map file.
  void
  do_print_to_mapfile(Mapfile* mapfile) const
  { mapfile->print_output_data(this, _("** relocs")); }

 private:
  // The relocs associated with this input section.
  Relocatable_relocs* rr_;
};

// Handle a GROUP section.

template<int size, bool big_endian>
class Output_data_group : public Output_section_data
{
 public:
  // The constructor clears *INPUT_SHNDXES.
  Output_data_group(Sized_relobj_file<size, big_endian>* relobj,
		    section_size_type entry_count,
		    elfcpp::Elf_Word flags,
		    std::vector<unsigned int>* input_shndxes);

  void
  do_write(Output_file*);

  // Write to a map file.
  void
  do_print_to_mapfile(Mapfile* mapfile) const
  { mapfile->print_output_data(this, _("** group")); }

  // Set final data size.
  void
  set_final_data_size()
  { this->set_data_size((this->input_shndxes_.size() + 1) * 4); }

 private:
  // The input object.
  Sized_relobj_file<size, big_endian>* relobj_;
  // The group flag word.
  elfcpp::Elf_Word flags_;
  // The section indexes of the input sections in this group.
  std::vector<unsigned int> input_shndxes_;
};

// Output_data_got is used to manage a GOT.  Each entry in the GOT is
// for one symbol--either a global symbol or a local symbol in an
// object.  The target specific code adds entries to the GOT as
// needed.  The GOT_SIZE template parameter is the size in bits of a
// GOT entry, typically 32 or 64.

class Output_data_got_base : public Output_section_data_build
{
 public:
  Output_data_got_base(uint64_t align)
    : Output_section_data_build(align)
  { }

  Output_data_got_base(off_t data_size, uint64_t align)
    : Output_section_data_build(data_size, align)
  { }

  // Reserve the slot at index I in the GOT.
  void
  reserve_slot(unsigned int i)
  { this->do_reserve_slot(i); }

 protected:
  // Reserve the slot at index I in the GOT.
  virtual void
  do_reserve_slot(unsigned int i) = 0;
};

template<int got_size, bool big_endian>
class Output_data_got : public Output_data_got_base
{
 public:
  typedef typename elfcpp::Elf_types<got_size>::Elf_Addr Valtype;

  Output_data_got()
    : Output_data_got_base(Output_data::default_alignment_for_size(got_size)),
      entries_(), free_list_()
  { }

  Output_data_got(off_t data_size)
    : Output_data_got_base(data_size,
			   Output_data::default_alignment_for_size(got_size)),
      entries_(), free_list_()
  {
    // For an incremental update, we have an existing GOT section.
    // Initialize the list of entries and the free list.
    this->entries_.resize(data_size / (got_size / 8));
    this->free_list_.init(data_size, false);
  }

  // Add an entry for a global symbol GSYM plus ADDEND to the GOT.
  // Return true if this is a new GOT entry, false if the symbol plus
  // addend was already in the GOT.
  bool
  add_global(Symbol* gsym, unsigned int got_type, uint64_t addend = 0);

  // Like add_global, but use the PLT offset of the global symbol if
  // it has one.
  bool
  add_global_plt(Symbol* gsym, unsigned int got_type, uint64_t addend = 0);

  // Like add_global, but for a TLS symbol where the value will be
  // offset using Target::tls_offset_for_global.
  bool
  add_global_tls(Symbol* gsym, unsigned int got_type, uint64_t addend = 0)
  { return this->add_global_plt(gsym, got_type, addend); }

  // Add an entry for a global symbol GSYM plus ADDEND to the GOT, and
  // add a dynamic relocation of type R_TYPE for the GOT entry.
  void
  add_global_with_rel(Symbol* gsym, unsigned int got_type,
		      Output_data_reloc_generic* rel_dyn, unsigned int r_type,
		      uint64_t addend = 0);

  // Add a pair of entries for a global symbol GSYM plus ADDEND to the
  // GOT, and add dynamic relocations of type R_TYPE_1 and R_TYPE_2,
  // respectively.
  void
  add_global_pair_with_rel(Symbol* gsym, unsigned int got_type,
			   Output_data_reloc_generic* rel_dyn,
			   unsigned int r_type_1, unsigned int r_type_2,
			   uint64_t addend = 0);

  // Add an entry for a local symbol plus ADDEND to the GOT.  This returns
  // true if this is a new GOT entry, false if the symbol already has a GOT
  // entry.
  bool
  add_local(Relobj* object, unsigned int sym_index, unsigned int got_type,
	    uint64_t addend = 0);

  // Like add_local, but use the PLT offset of the local symbol if it
  // has one.
  bool
  add_local_plt(Relobj* object, unsigned int sym_index, unsigned int got_type,
		uint64_t addend = 0);

  // Like add_local, but for a TLS symbol where the value will be
  // offset using Target::tls_offset_for_local.
  bool
  add_local_tls(Relobj* object, unsigned int sym_index, unsigned int got_type,
		uint64_t addend = 0)
  { return this->add_local_plt(object, sym_index, got_type, addend); }

  // Add an entry for a local symbol plus ADDEND to the GOT, and add a dynamic
  // relocation of type R_TYPE for the GOT entry.
  void
  add_local_with_rel(Relobj* object, unsigned int sym_index,
		     unsigned int got_type, Output_data_reloc_generic* rel_dyn,
		     unsigned int r_type, uint64_t addend = 0);

  // Add a pair of entries for a local symbol plus ADDEND to the GOT, and add
  // a dynamic relocation of type R_TYPE using the section symbol of
  // the output section to which input section SHNDX maps, on the first.
  // The first got entry will have a value of zero, the second the
  // value of the local symbol.
  void
  add_local_pair_with_rel(Relobj* object, unsigned int sym_index,
			  unsigned int shndx, unsigned int got_type,
			  Output_data_reloc_generic* rel_dyn,
			  unsigned int r_type, uint64_t addend = 0);

  // Add a pair of entries for a local symbol plus ADDEND to the GOT,
  // and add a dynamic relocation of type R_TYPE using STN_UNDEF on
  // the first.  The first got entry will have a value of zero, the
  // second the value of the local symbol plus ADDEND offset by
  // Target::tls_offset_for_local.
  void
  add_local_tls_pair(Relobj* object, unsigned int sym_index,
		     unsigned int got_type,
		     Output_data_reloc_generic* rel_dyn,
		     unsigned int r_type, uint64_t addend = 0);

  // Add a constant to the GOT.  This returns the offset of the new
  // entry from the start of the GOT.
  unsigned int
  add_constant(Valtype constant)
  { return this->add_got_entry(Got_entry(constant)); }

  // Add a pair of constants to the GOT.  This returns the offset of
  // the new entry from the start of the GOT.
  unsigned int
  add_constant_pair(Valtype c1, Valtype c2)
  { return this->add_got_entry_pair(Got_entry(c1), Got_entry(c2)); }

  // Replace GOT entry I with a new constant.
  void
  replace_constant(unsigned int i, Valtype constant)
  {
    this->replace_got_entry(i, Got_entry(constant));
  }

  // Reserve a slot in the GOT for a local symbol plus ADDEND.
  void
  reserve_local(unsigned int i, Relobj* object, unsigned int sym_index,
		unsigned int got_type, uint64_t addend = 0);

  // Reserve a slot in the GOT for a global symbol plus ADDEND.
  void
  reserve_global(unsigned int i, Symbol* gsym, unsigned int got_type,
		 uint64_t addend = 0);

 protected:
  // Write out the GOT table.
  void
  do_write(Output_file*);

  // Write to a map file.
  void
  do_print_to_mapfile(Mapfile* mapfile) const
  { mapfile->print_output_data(this, _("** GOT")); }

  // Reserve the slot at index I in the GOT.
  virtual void
  do_reserve_slot(unsigned int i)
  { this->free_list_.remove(i * got_size / 8, (i + 1) * got_size / 8); }

  // Return the number of words in the GOT.
  unsigned int
  num_entries () const
  { return this->entries_.size(); }

  // Return the offset into the GOT of GOT entry I.
  unsigned int
  got_offset(unsigned int i) const
  { return i * (got_size / 8); }

 private:
  // This POD class holds a single GOT entry.
  class Got_entry
  {
   public:
    // Create a zero entry.
    Got_entry()
      : local_sym_index_(RESERVED_CODE), use_plt_or_tls_offset_(false),
	addend_(0)
    { this->u_.constant = 0; }

    // Create a global symbol entry.
    Got_entry(Symbol* gsym, bool use_plt_or_tls_offset, uint64_t addend)
      : local_sym_index_(GSYM_CODE),
	use_plt_or_tls_offset_(use_plt_or_tls_offset), addend_(addend)
    { this->u_.gsym = gsym; }

    // Create a local symbol entry.
    Got_entry(Relobj* object, unsigned int local_sym_index,
	      bool use_plt_or_tls_offset, uint64_t addend)
      : local_sym_index_(local_sym_index),
	use_plt_or_tls_offset_(use_plt_or_tls_offset), addend_(addend)
    {
      gold_assert(local_sym_index != GSYM_CODE
		  && local_sym_index != CONSTANT_CODE
		  && local_sym_index != RESERVED_CODE
		  && local_sym_index == this->local_sym_index_);
      this->u_.object = object;
    }

    // Create a constant entry.  The constant is a host value--it will
    // be swapped, if necessary, when it is written out.
    explicit Got_entry(Valtype constant)
      : local_sym_index_(CONSTANT_CODE), use_plt_or_tls_offset_(false)
    { this->u_.constant = constant; }

    // Write the GOT entry to an output view.
    void
    write(Output_data_got_base* got, unsigned int got_indx,
	  unsigned char* pov) const;

   private:
    enum
    {
      GSYM_CODE = 0x7fffffff,
      CONSTANT_CODE = 0x7ffffffe,
      RESERVED_CODE = 0x7ffffffd
    };

    union
    {
      // For a local symbol, the object.
      Relobj* object;
      // For a global symbol, the symbol.
      Symbol* gsym;
      // For a constant, the constant.
      Valtype constant;
    } u_;
    // For a local symbol, the local symbol index.  This is GSYM_CODE
    // for a global symbol, or CONSTANT_CODE for a constant.
    unsigned int local_sym_index_ : 31;
    // Whether to use the PLT offset of the symbol if it has one.
    // For TLS symbols, whether to offset the symbol value.
    bool use_plt_or_tls_offset_ : 1;
    // The addend.
    uint64_t addend_;
  };

  typedef std::vector<Got_entry> Got_entries;

  // Create a new GOT entry and return its offset.
  unsigned int
  add_got_entry(Got_entry got_entry);

  // Create a pair of new GOT entries and return the offset of the first.
  unsigned int
  add_got_entry_pair(Got_entry got_entry_1, Got_entry got_entry_2);

  // Replace GOT entry I with a new value.
  void
  replace_got_entry(unsigned int i, Got_entry got_entry);

  // Return the offset into the GOT of the last entry added.
  unsigned int
  last_got_offset() const
  { return this->got_offset(this->num_entries() - 1); }

  // Set the size of the section.
  void
  set_got_size()
  { this->set_current_data_size(this->got_offset(this->num_entries())); }

  // The list of GOT entries.
  Got_entries entries_;

  // List of available regions within the section, for incremental
  // update links.
  Free_list free_list_;
};

// Output_data_dynamic is used to hold the data in SHT_DYNAMIC
// section.

class Output_data_dynamic : public Output_section_data
{
 public:
  Output_data_dynamic(Stringpool* pool)
    : Output_section_data(Output_data::default_alignment()),
      entries_(), pool_(pool)
  { }

  // Add a new dynamic entry with a fixed numeric value.
  void
  add_constant(elfcpp::DT tag, unsigned int val)
  { this->add_entry(Dynamic_entry(tag, val)); }

  // Add a new dynamic entry with the address of output data.
  void
  add_section_address(elfcpp::DT tag, const Output_data* od)
  { this->add_entry(Dynamic_entry(tag, od, false)); }

  // Add a new dynamic entry with the address of output data
  // plus a constant offset.
  void
  add_section_plus_offset(elfcpp::DT tag, const Output_data* od,
			  unsigned int offset)
  { this->add_entry(Dynamic_entry(tag, od, offset)); }

  // Add a new dynamic entry with the size of output data.
  void
  add_section_size(elfcpp::DT tag, const Output_data* od)
  { this->add_entry(Dynamic_entry(tag, od, true)); }

  // Add a new dynamic entry with the total size of two output datas.
  void
  add_section_size(elfcpp::DT tag, const Output_data* od,
		   const Output_data* od2)
  { this->add_entry(Dynamic_entry(tag, od, od2)); }

  // Add a new dynamic entry with the address of a symbol.
  void
  add_symbol(elfcpp::DT tag, const Symbol* sym)
  { this->add_entry(Dynamic_entry(tag, sym)); }

  // Add a new dynamic entry with a string.
  void
  add_string(elfcpp::DT tag, const char* str)
  { this->add_entry(Dynamic_entry(tag, this->pool_->add(str, true, NULL))); }

  void
  add_string(elfcpp::DT tag, const std::string& str)
  { this->add_string(tag, str.c_str()); }

  // Add a new dynamic entry with custom value.
  void
  add_custom(elfcpp::DT tag)
  { this->add_entry(Dynamic_entry(tag)); }

  // Get a dynamic entry offset.
  unsigned int
  get_entry_offset(elfcpp::DT tag) const;

 protected:
  // Adjust the output section to set the entry size.
  void
  do_adjust_output_section(Output_section*);

  // Set the final data size.
  void
  set_final_data_size();

  // Write out the dynamic entries.
  void
  do_write(Output_file*);

  // Write to a map file.
  void
  do_print_to_mapfile(Mapfile* mapfile) const
  { mapfile->print_output_data(this, _("** dynamic")); }

 private:
  // This POD class holds a single dynamic entry.
  class Dynamic_entry
  {
   public:
    // Create an entry with a fixed numeric value.
    Dynamic_entry(elfcpp::DT tag, unsigned int val)
      : tag_(tag), offset_(DYNAMIC_NUMBER)
    { this->u_.val = val; }

    // Create an entry with the size or address of a section.
    Dynamic_entry(elfcpp::DT tag, const Output_data* od, bool section_size)
      : tag_(tag),
	offset_(section_size
		? DYNAMIC_SECTION_SIZE
		: DYNAMIC_SECTION_ADDRESS)
    {
      this->u_.od = od;
      this->od2 = NULL;
    }

    // Create an entry with the size of two sections.
    Dynamic_entry(elfcpp::DT tag, const Output_data* od, const Output_data* od2)
      : tag_(tag),
	offset_(DYNAMIC_SECTION_SIZE)
    {
      this->u_.od = od;
      this->od2 = od2;
    }

    // Create an entry with the address of a section plus a constant offset.
    Dynamic_entry(elfcpp::DT tag, const Output_data* od, unsigned int offset)
      : tag_(tag),
	offset_(offset)
    { this->u_.od = od; }

    // Create an entry with the address of a symbol.
    Dynamic_entry(elfcpp::DT tag, const Symbol* sym)
      : tag_(tag), offset_(DYNAMIC_SYMBOL)
    { this->u_.sym = sym; }

    // Create an entry with a string.
    Dynamic_entry(elfcpp::DT tag, const char* str)
      : tag_(tag), offset_(DYNAMIC_STRING)
    { this->u_.str = str; }

    // Create an entry with a custom value.
    Dynamic_entry(elfcpp::DT tag)
      : tag_(tag), offset_(DYNAMIC_CUSTOM)
    { }

    // Return the tag of this entry.
    elfcpp::DT
    tag() const
    { return this->tag_; }

    // Write the dynamic entry to an output view.
    template<int size, bool big_endian>
    void
    write(unsigned char* pov, const Stringpool*) const;

   private:
    // Classification is encoded in the OFFSET field.
    enum Classification
    {
      // Section address.
      DYNAMIC_SECTION_ADDRESS = 0,
      // Number.
      DYNAMIC_NUMBER = -1U,
      // Section size.
      DYNAMIC_SECTION_SIZE = -2U,
      // Symbol address.
      DYNAMIC_SYMBOL = -3U,
      // String.
      DYNAMIC_STRING = -4U,
      // Custom value.
      DYNAMIC_CUSTOM = -5U
      // Any other value indicates a section address plus OFFSET.
    };

    union
    {
      // For DYNAMIC_NUMBER.
      unsigned int val;
      // For DYNAMIC_SECTION_SIZE and section address plus OFFSET.
      const Output_data* od;
      // For DYNAMIC_SYMBOL.
      const Symbol* sym;
      // For DYNAMIC_STRING.
      const char* str;
    } u_;
    // For DYNAMIC_SYMBOL with two sections.
    const Output_data* od2;
    // The dynamic tag.
    elfcpp::DT tag_;
    // The type of entry (Classification) or offset within a section.
    unsigned int offset_;
  };

  // Add an entry to the list.
  void
  add_entry(const Dynamic_entry& entry)
  { this->entries_.push_back(entry); }

  // Sized version of write function.
  template<int size, bool big_endian>
  void
  sized_write(Output_file* of);

  // The type of the list of entries.
  typedef std::vector<Dynamic_entry> Dynamic_entries;

  // The entries.
  Dynamic_entries entries_;
  // The pool used for strings.
  Stringpool* pool_;
};

// Output_symtab_xindex is used to handle SHT_SYMTAB_SHNDX sections,
// which may be required if the object file has more than
// SHN_LORESERVE sections.

class Output_symtab_xindex : public Output_section_data
{
 public:
  Output_symtab_xindex(size_t symcount)
    : Output_section_data(symcount * 4, 4, true),
      entries_()
  { }

  // Add an entry: symbol number SYMNDX has section SHNDX.
  void
  add(unsigned int symndx, unsigned int shndx)
  { this->entries_.push_back(std::make_pair(symndx, shndx)); }

 protected:
  void
  do_write(Output_file*);

  // Write to a map file.
  void
  do_print_to_mapfile(Mapfile* mapfile) const
  { mapfile->print_output_data(this, _("** symtab xindex")); }

 private:
  template<bool big_endian>
  void
  endian_do_write(unsigned char*);

  // It is likely that most symbols will not require entries.  Rather
  // than keep a vector for all symbols, we keep pairs of symbol index
  // and section index.
  typedef std::vector<std::pair<unsigned int, unsigned int> > Xindex_entries;

  // The entries we need.
  Xindex_entries entries_;
};

// A relaxed input section.
class Output_relaxed_input_section : public Output_section_data_build
{
 public:
  // We would like to call relobj->section_addralign(shndx) to get the
  // alignment but we do not want the constructor to fail.  So callers
  // are repsonsible for ensuring that.
  Output_relaxed_input_section(Relobj* relobj, unsigned int shndx,
			       uint64_t addralign)
    : Output_section_data_build(addralign), relobj_(relobj), shndx_(shndx)
  { }

  // Return the Relobj of this relaxed input section.
  Relobj*
  relobj() const
  { return this->relobj_; }

  // Return the section index of this relaxed input section.
  unsigned int
  shndx() const
  { return this->shndx_; }

 protected:
  void
  set_relobj(Relobj* relobj)
  { this->relobj_ = relobj; }

  void
  set_shndx(unsigned int shndx)
  { this->shndx_ = shndx; }

 private:
  Relobj* relobj_;
  unsigned int shndx_;
};

// This class describes properties of merge data sections.  It is used
// as a key type for maps.
class Merge_section_properties
{
 public:
  Merge_section_properties(bool is_string, uint64_t entsize,
			     uint64_t addralign)
    : is_string_(is_string), entsize_(entsize), addralign_(addralign)
  { }

  // Whether this equals to another Merge_section_properties MSP.
  bool
  eq(const Merge_section_properties& msp) const
  {
    return ((this->is_string_ == msp.is_string_)
	    && (this->entsize_ == msp.entsize_)
	    && (this->addralign_ == msp.addralign_));
  }

  // Compute a hash value for this using 64-bit FNV-1a hash.
  size_t
  hash_value() const
  {
    uint64_t h = 14695981039346656037ULL;	// FNV offset basis.
    uint64_t prime = 1099511628211ULL;
    h = (h ^ static_cast<uint64_t>(this->is_string_)) * prime;
    h = (h ^ static_cast<uint64_t>(this->entsize_)) * prime;
    h = (h ^ static_cast<uint64_t>(this->addralign_)) * prime;
    return h;
  }

  // Functors for associative containers.
  struct equal_to
  {
    bool
    operator()(const Merge_section_properties& msp1,
	       const Merge_section_properties& msp2) const
    { return msp1.eq(msp2); }
  };

  struct hash
  {
    size_t
    operator()(const Merge_section_properties& msp) const
    { return msp.hash_value(); }
  };

 private:
  // Whether this merge data section is for strings.
  bool is_string_;
  // Entsize of this merge data section.
  uint64_t entsize_;
  // Address alignment.
  uint64_t addralign_;
};

// This class is used to speed up look up of special input sections in an
// Output_section.

class Output_section_lookup_maps
{
 public:
  Output_section_lookup_maps()
    : is_valid_(true), merge_sections_by_properties_(),
      relaxed_input_sections_by_id_()
  { }

  // Whether the maps are valid.
  bool
  is_valid() const
  { return this->is_valid_; }

  // Invalidate the maps.
  void
  invalidate()
  { this->is_valid_ = false; }

  // Clear the maps.
  void
  clear()
  {
    this->merge_sections_by_properties_.clear();
    this->relaxed_input_sections_by_id_.clear();
    // A cleared map is valid.
    this->is_valid_ = true;
  }

  // Find a merge section by merge section properties.  Return NULL if none
  // is found.
  Output_merge_base*
  find_merge_section(const Merge_section_properties& msp) const
  {
    gold_assert(this->is_valid_);
    Merge_sections_by_properties::const_iterator p =
      this->merge_sections_by_properties_.find(msp);
    return p != this->merge_sections_by_properties_.end() ? p->second : NULL;
  }

  // Add a merge section pointed by POMB with properties MSP.
  void
  add_merge_section(const Merge_section_properties& msp,
		    Output_merge_base