text: // object.h -- support for an object file for linking in gold  -*- C++ -*-
  
  // Copyright (C) 2006-2020 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_OBJECT_H
  #define GOLD_OBJECT_H
  
  #include <string>
  #include <vector>
  
  #include "elfcpp.h"
  #include "elfcpp_file.h"
  #include "fileread.h"
  #include "target.h"
  #include "archive.h"
  
  namespace gold
  {
  
  class General_options;
  class Task;
  class Cref;
  class Layout;
  class Kept_section;
  class Output_data;
  class Output_section;
  class Output_section_data;
  class Output_file;
  class Output_symtab_xindex;
  class Pluginobj;
  class Dynobj;
  class Object_merge_map;
  class Relocatable_relocs;
  struct Symbols_data;
  
  template<typename Stringpool_char>
  class Stringpool_template;
  
  // Data to pass from read_symbols() to add_symbols().
  
  struct Read_symbols_data
  {
    Read_symbols_data()
      : section_headers(NULL), section_names(NULL), symbols(NULL),
        symbol_names(NULL), versym(NULL), verdef(NULL), verneed(NULL)
    { }
  
    ~Read_symbols_data();
  
    // Section headers.
    File_view* section_headers;
    // Section names.
    File_view* section_names;
    // Size of section name data in bytes.
    section_size_type section_names_size;
    // Symbol data.
    File_view* symbols;
    // Size of symbol data in bytes.
    section_size_type symbols_size;
    // Offset of external symbols within symbol data.  This structure
    // sometimes contains only external symbols, in which case this will
    // be zero.  Sometimes it contains all symbols.
    section_offset_type external_symbols_offset;
    // Symbol names.
    File_view* symbol_names;
    // Size of symbol name data in bytes.
    section_size_type symbol_names_size;
  
    // Version information.  This is only used on dynamic objects.
    // Version symbol data (from SHT_GNU_versym section).
    File_view* versym;
    section_size_type versym_size;
    // Version definition data (from SHT_GNU_verdef section).
    File_view* verdef;
    section_size_type verdef_size;
    unsigned int verdef_info;
    // Needed version data  (from SHT_GNU_verneed section).
    File_view* verneed;
    section_size_type verneed_size;
    unsigned int verneed_info;
  };
  
  // Information used to print error messages.
  
  struct Symbol_location_info
  {
    std::string source_file;
    std::string enclosing_symbol_name;
    elfcpp::STT enclosing_symbol_type;
  };
  
  // Data about a single relocation section.  This is read in
  // read_relocs and processed in scan_relocs.
  
  struct Section_relocs
  {
    Section_relocs()
      : contents(NULL)
    { }
  
    ~Section_relocs()
    { delete this->contents; }
  
    // Index of reloc section.
    unsigned int reloc_shndx;
    // Index of section that relocs apply to.
    unsigned int data_shndx;
    // Contents of reloc section.
    File_view* contents;
    // Reloc section type.
    unsigned int sh_type;
    // Number of reloc entries.
    size_t reloc_count;
    // Output section.
    Output_section* output_section;
    // Whether this section has special handling for offsets.
    bool needs_special_offset_handling;
    // Whether the data section is allocated (has the SHF_ALLOC flag set).
    bool is_data_section_allocated;
  };
  
  // Relocations in an object file.  This is read in read_relocs and
  // processed in scan_relocs.
  
  struct Read_relocs_data
  {
    Read_relocs_data()
      : local_symbols(NULL)
    { }
  
    ~Read_relocs_data()
    { delete this->local_symbols; }
  
    typedef std::vector<Section_relocs> Relocs_list;
    // The relocations.
    Relocs_list relocs;
    // The local symbols.
    File_view* local_symbols;
  };
  
  // The Xindex class manages section indexes for objects with more than
  // 0xff00 sections.
  
  class Xindex
  {
   public:
    Xindex(int large_shndx_offset)
      : large_shndx_offset_(large_shndx_offset), symtab_xindex_()
    { }
  
    // Initialize the symtab_xindex_ array, given the object and the
    // section index of the symbol table to use.
    template<int size, bool big_endian>
    void
    initialize_symtab_xindex(Object*, unsigned int symtab_shndx);
  
    // Read in the symtab_xindex_ array, given its section index.
    // PSHDRS may optionally point to the section headers.
    template<int size, bool big_endian>
    void
    read_symtab_xindex(Object*, unsigned int xindex_shndx,
  		     const unsigned char* pshdrs);
  
    // Symbol SYMNDX in OBJECT has a section of SHN_XINDEX; return the
    // real section index.
    unsigned int
    sym_xindex_to_shndx(Object* object, unsigned int symndx);
  
   private:
    // The type of the array giving the real section index for symbols
    // whose st_shndx field holds SHN_XINDEX.
    typedef std::vector<unsigned int> Symtab_xindex;
  
    // Adjust a section index if necessary.  This should only be called
    // for ordinary section indexes.
    unsigned int
    adjust_shndx(unsigned int shndx)
    {
      if (shndx >= elfcpp::SHN_LORESERVE)
        shndx += this->large_shndx_offset_;
      return shndx;
    }
  
    // Adjust to apply to large section indexes.
    int large_shndx_offset_;
    // The data from the SHT_SYMTAB_SHNDX section.
    Symtab_xindex symtab_xindex_;
  };
  
  // A GOT offset list.  A symbol may have more than one GOT offset
  // (e.g., when mixing modules compiled with two different TLS models),
  // but will usually have at most one.  GOT_TYPE identifies the type of
  // GOT entry; its values are specific to each target.
  
  class Got_offset_list
  {
   public:
    Got_offset_list()
      : got_type_(-1U), got_offset_(0), got_next_(NULL)
    { }
  
    Got_offset_list(unsigned int got_type, unsigned int got_offset)
      : got_type_(got_type), got_offset_(got_offset), got_next_(NULL)
    { }
  
    ~Got_offset_list()
    {
      if (this->got_next_ != NULL)
        {
          delete this->got_next_;
          this->got_next_ = NULL;
        }
    }
  
    // Initialize the fields to their default values.
    void
    init()
    {
      this->got_type_ = -1U;
      this->got_offset_ = 0;
      this->got_next_ = NULL;
    }
  
    // Set the offset for the GOT entry of type GOT_TYPE.
    void
    set_offset(unsigned int got_type, unsigned int got_offset)
    {
      if (this->got_type_ == -1U)
        {
          this->got_type_ = got_type;
          this->got_offset_ = got_offset;
        }
      else
        {
          for (Got_offset_list* g = this; g != NULL; g = g->got_next_)
            {
              if (g->got_type_ == got_type)
                {
                  g->got_offset_ = got_offset;
                  return;
                }
            }
          Got_offset_list* g = new Got_offset_list(got_type, got_offset);
          g->got_next_ = this->got_next_;
          this->got_next_ = g;
        }
    }
  
    // Return the offset for a GOT entry of type GOT_TYPE.
    unsigned int
    get_offset(unsigned int got_type) const
    {
      for (const Got_offset_list* g = this; g != NULL; g = g->got_next_)
        {
          if (g->got_type_ == got_type)
            return g->got_offset_;
        }
      return -1U;
    }
  
    // Return a pointer to the list, or NULL if the list is empty.
    const Got_offset_list*
    get_list() const
    {
      if (this->got_type_ == -1U)
        return NULL;
      return this;
    }
  
    // Abstract visitor class for iterating over GOT offsets.
    class Visitor
    {
     public:
      Visitor()
      { }
  
      virtual
      ~Visitor()
      { }
  
      virtual void
      visit(unsigned int, unsigned int) = 0;
    };
  
    // Loop over all GOT offset entries, calling a visitor class V for each.
    void
    for_all_got_offsets(Visitor* v) const
    {
      if (this->got_type_ == -1U)
        return;
      for (const Got_offset_list* g = this; g != NULL; g = g->got_next_)
        v->visit(g->got_type_, g->got_offset_);
    }
  
   private:
    unsigned int got_type_;
    unsigned int got_offset_;
    Got_offset_list* got_next_;
  };
  
  // The Local_got_entry_key used to index the GOT offsets for local
  // non-TLS symbols, and tp-relative offsets for TLS symbols.
  
  class Local_got_entry_key
  {
   public:
    Local_got_entry_key(unsigned int symndx, uint64_t addend)
      : symndx_(symndx), addend_(addend)
    {}
  
    // Whether this equals to another Local_got_entry_key.
    bool
    eq(const Local_got_entry_key& key) const
    {
      return (this->symndx_ == key.symndx_ && this->addend_ == key.addend_);
    }
  
    // 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->symndx_)) * prime;
      h = (h ^ static_cast<uint64_t>(this->addend_)) * prime;
      return h;
    }
  
    // Functors for associative containers.
    struct equal_to
    {
      bool
      operator()(const Local_got_entry_key& key1,
                 const Local_got_entry_key& key2) const
      { return key1.eq(key2); }
    };
  
    struct hash
    {
      size_t
      operator()(const Local_got_entry_key& key) const
      { return key.hash_value(); }
    };
  
   private:
    // The local symbol index.
    unsigned int symndx_;
    // The addend.
    uint64_t addend_;
  };
  
  // Type for mapping section index to uncompressed size and contents.
  
  struct Compressed_section_info
  {
    section_size_type size;
    elfcpp::Elf_Xword flag;
    uint64_t addralign;
    const unsigned char* contents;
  };
  typedef std::map<unsigned int, Compressed_section_info> Compressed_section_map;
  
  template<int size, bool big_endian>
  Compressed_section_map*
  build_compressed_section_map(const unsigned char* pshdrs, unsigned int shnum,
  			     const char* names, section_size_type names_size,
  			     Object* obj, bool decompress_if_needed);
  
  // Object is an abstract base class which represents either a 32-bit
  // or a 64-bit input object.  This can be a regular object file
  // (ET_REL) or a shared object (ET_DYN).
  
  class Object
  {
   public:
    typedef std::vector<Symbol*> Symbols;
  
    // NAME is the name of the object as we would report it to the user
    // (e.g., libfoo.a(bar.o) if this is in an archive.  INPUT_FILE is
    // used to read the file.  OFFSET is the offset within the input
    // file--0 for a .o or .so file, something else for a .a file.
    Object(const std::string& name, Input_file* input_file, bool is_dynamic,
  	 off_t offset = 0)
      : name_(name), input_file_(input_file), offset_(offset), shnum_(-1U),
        is_dynamic_(is_dynamic), is_needed_(false), uses_split_stack_(false),
        has_no_split_stack_(false), no_export_(false),
        is_in_system_directory_(false), as_needed_(false), xindex_(NULL),
        compressed_sections_(NULL)
    {
      if (input_file != NULL)
        {
  	input_file->file().add_object();
  	this->is_in_system_directory_ = input_file->is_in_system_directory();
  	this->as_needed_ = input_file->options().as_needed();
        }
    }
  
    virtual ~Object()
    {
      if (this->input_file_ != NULL)
        this->input_file_->file().remove_object();
    }
  
    // Return the name of the object as we would report it to the user.
    const std::string&
    name() const
    { return this->name_; }
  
    // Get the offset into the file.
    off_t
    offset() const
    { return this->offset_; }
  
    // Return whether this is a dynamic object.
    bool
    is_dynamic() const
    { return this->is_dynamic_; }
  
    // Return the word size of the object file.
    virtual int elfsize() const = 0;
  
    // Return TRUE if this is a big-endian object file.
    virtual bool is_big_endian() const = 0;
  
    // Return whether this object is needed--true if it is a dynamic
    // object which defines some symbol referenced by a regular object.
    // We keep the flag here rather than in Dynobj for convenience when
    // setting it.
    bool
    is_needed() const
    { return this->is_needed_; }
  
    // Record that this object is needed.
    void
    set_is_needed()
    { this->is_needed_ = true; }
  
    // Return whether this object was compiled with -fsplit-stack.
    bool
    uses_split_stack() const
    { return this->uses_split_stack_; }
  
    // Return whether this object contains any functions compiled with
    // the no_split_stack attribute.
    bool
    has_no_split_stack() const
    { return this->has_no_split_stack_; }
  
    // Returns NULL for Objects that are not dynamic objects.  This method
    // is overridden in the Dynobj class.
    Dynobj*
    dynobj()
    { return this->do_dynobj(); }
  
    // Returns NULL for Objects that are not plugin objects.  This method
    // is overridden in the Pluginobj class.
    Pluginobj*
    pluginobj()
    { return this->do_pluginobj(); }
  
    // Get the file.  We pass on const-ness.
    Input_file*
    input_file()
    {
      gold_assert(this->input_file_ != NULL);
      return this->input_file_;
    }
  
    const Input_file*
    input_file() const
    {
      gold_assert(this->input_file_ != NULL);
      return this->input_file_;
    }
  
    // Lock the underlying file.
    void
    lock(const Task* t)
    {
      if (this->input_file_ != NULL)
        this->input_file_->file().lock(t);
    }
  
    // Unlock the underlying file.
    void
    unlock(const Task* t)
    {
      if (this->input_file_ != NULL)
        this->input_file()->file().unlock(t);
    }
  
    // Return whether the underlying file is locked.
    bool
    is_locked() const
    { return this->input_file_ != NULL && this->input_file_->file().is_locked(); }
  
    // Return the token, so that the task can be queued.
    Task_token*
    token()
    {
      if (this->input_file_ == NULL)
        return NULL;
      return this->input_file()->file().token();
    }
  
    // Release the underlying file.
    void
    release()
    {
      if (this->input_file_ != NULL)
        this->input_file()->file().release();
    }
  
    // Return whether we should just read symbols from this file.
    bool
    just_symbols() const
    { return this->input_file()->just_symbols(); }
  
    // Return whether this is an incremental object.
    bool
    is_incremental() const
    { return this->do_is_incremental(); }
  
    // Return the last modified time of the file.
    Timespec
    get_mtime()
    { return this->do_get_mtime(); }
  
    // Get the number of sections.
    unsigned int
    shnum() const
    { return this->shnum_; }
  
    // Return a view of the contents of a section.  Set *PLEN to the
    // size.  CACHE is a hint as in File_read::get_view.
    const unsigned char*
    section_contents(unsigned int shndx, section_size_type* plen, bool cache);
  
    // Adjust a symbol's section index as needed.  SYMNDX is the index
    // of the symbol and SHNDX is the symbol's section from
    // get_st_shndx.  This returns the section index.  It sets
    // *IS_ORDINARY to indicate whether this is a normal section index,
    // rather than a special code between SHN_LORESERVE and
    // SHN_HIRESERVE.
    unsigned int
    adjust_sym_shndx(unsigned int symndx, unsigned int shndx, bool* is_ordinary)
    {
      if (shndx < elfcpp::SHN_LORESERVE)
        *is_ordinary = true;
      else if (shndx == elfcpp::SHN_XINDEX)
        {
  	if (this->xindex_ == NULL)
  	  this->xindex_ = this->do_initialize_xindex();
  	shndx = this->xindex_->sym_xindex_to_shndx(this, symndx);
  	*is_ordinary = true;
        }
      else
        *is_ordinary = false;
      return shndx;
    }
  
    // Return the size of a section given a section index.
    uint64_t
    section_size(unsigned int shndx)
    { return this->do_section_size(shndx); }
  
    // Return the name of a section given a section index.
    std::string
    section_name(unsigned int shndx) const
    { return this->do_section_name(shndx); }
  
    // Return the section flags given a section index.
    uint64_t
    section_flags(unsigned int shndx)
    { return this->do_section_flags(shndx); }
  
    // Return the section entsize given a section index.
    uint64_t
    section_entsize(unsigned int shndx)
    { return this->do_section_entsize(shndx); }
  
    // Return the section address given a section index.
    uint64_t
    section_address(unsigned int shndx)
    { return this->do_section_address(shndx); }
  
    // Return the section type given a section index.
    unsigned int
    section_type(unsigned int shndx)
    { return this->do_section_type(shndx); }
  
    // Return the section link field given a section index.
    unsigned int
    section_link(unsigned int shndx)
    { return this->do_section_link(shndx); }
  
    // Return the section info field given a section index.
    unsigned int
    section_info(unsigned int shndx)
    { return this->do_section_info(shndx); }
  
    // Return the required section alignment given a section index.
    uint64_t
    section_addralign(unsigned int shndx)
    { return this->do_section_addralign(shndx); }
  
    // Return the output section given a section index.
    Output_section*
    output_section(unsigned int shndx) const
    { return this->do_output_section(shndx); }
  
    // Given a section index, return its address.
    // The return value will be -1U if the section is specially mapped,
    // such as a merge section.
    uint64_t
    output_section_address(unsigned int shndx)
    { return this->do_output_section_address(shndx); }
  
    // Given a section index, return the offset in the Output_section.
    // The return value will be -1U if the section is specially mapped,
    // such as a merge section.
    uint64_t
    output_section_offset(unsigned int shndx) const
    { return this->do_output_section_offset(shndx); }
  
    // Read the symbol information.
    void
    read_symbols(Read_symbols_data* sd)
    { return this->do_read_symbols(sd); }
  
    // Pass sections which should be included in the link to the Layout
    // object, and record where the sections go in the output file.
    void
    layout(Symbol_table* symtab, Layout* layout, Read_symbols_data* sd)
    { this->do_layout(symtab, layout, sd); }
  
    // Add symbol information to the global symbol table.
    void
    add_symbols(Symbol_table* symtab, Read_symbols_data* sd, Layout *layout)
    { this->do_add_symbols(symtab, sd, layout); }
  
    // Add symbol information to the global symbol table.
    Archive::Should_include
    should_include_member(Symbol_table* symtab, Layout* layout,
  			Read_symbols_data* sd, std::string* why)
    { return this->do_should_include_member(symtab, layout, sd, why); }
  
    // Iterate over global symbols, calling a visitor class V for each.
    void
    for_all_global_symbols(Read_symbols_data* sd,
  			 Library_base::Symbol_visitor_base* v)
    { return this->do_for_all_global_symbols(sd, v); }
  
    // Iterate over local symbols, calling a visitor class V for each GOT offset
    // associated with a local symbol.
    void
    for_all_local_got_entries(Got_offset_list::Visitor* v) const
    { this->do_for_all_local_got_entries(v); }
  
    // Functions and types for the elfcpp::Elf_file interface.  This
    // permit us to use Object as the File template parameter for
    // elfcpp::Elf_file.
  
    // The View class is returned by view.  It must support a single
    // method, data().  This is trivial, because get_view does what we
    // need.
    class View
    {
     public:
      View(const unsigned char* p)
        : p_(p)
      { }
  
      const unsigned char*
      data() const
      { return this->p_; }
  
     private:
      const unsigned char* p_;
    };
  
    // Return a View.
    View
    view(off_t file_offset, section_size_type data_size)
    { return View(this->get_view(file_offset, data_size, true, true)); }
  
    // Report an error.
    void
    error(const char* format, ...) const ATTRIBUTE_PRINTF_2;
  
    // A location in the file.
    struct Location
    {
      off_t file_offset;
      off_t data_size;
  
      Location(off_t fo, section_size_type ds)
        : file_offset(fo), data_size(ds)
      { }
    };
  
    // Get a View given a Location.
    View view(Location loc)
    { return View(this->get_view(loc.file_offset, loc.data_size, true, true)); }
  
    // Get a view into the underlying file.
    const unsigned char*
    get_view(off_t start, section_size_type size, bool aligned, bool cache)
    {
      return this->input_file()->file().get_view(this->offset_, start, size,
  					       aligned, cache);
    }
  
    // Get a lasting view into the underlying file.
    File_view*
    get_lasting_view(off_t start, section_size_type size, bool aligned,
  		   bool cache)
    {
      return this->input_file()->file().get_lasting_view(this->offset_, start,
  						       size, aligned, cache);
    }
  
    // Read data from the underlying file.
    void
    read(off_t start, section_size_type size, void* p)
    { this->input_file()->file().read(start + this->offset_, size, p); }
  
    // Read multiple data from the underlying file.
    void
    read_multiple(const File_read::Read_multiple& rm)
    { this->input_file()->file().read_multiple(this->offset_, rm); }
  
    // Stop caching views in the underlying file.
    void
    clear_view_cache_marks()
    {
      if (this->input_file_ != NULL)
        this->input_file_->file().clear_view_cache_marks();
    }
  
    // Get the number of global symbols defined by this object, and the
    // number of the symbols whose final definition came from this
    // object.
    void
    get_global_symbol_counts(const Symbol_table* symtab, size_t* defined,
  			   size_t* used) const
    { this->do_get_global_symbol_counts(symtab, defined, used); }
  
    // Get the symbols defined in this object.
    const Symbols*
    get_global_symbols() const
    { return this->do_get_global_symbols(); }
  
    // Set flag that this object was found in a system directory.
    void
    set_is_in_system_directory()
    { this->is_in_system_directory_ = true; }
  
    // Return whether this object was found in a system directory.
    bool
    is_in_system_directory() const
    { return this->is_in_system_directory_; }
  
    // Set flag that this object was linked with --as-needed.
    void
    set_as_needed()
    { this->as_needed_ = true; }
  
    // Clear flag that this object was linked with --as-needed.
    void
    clear_as_needed()
    { this->as_needed_ = false; }
  
    // Return whether this object was linked with --as-needed.
    bool
    as_needed() const
    { return this->as_needed_; }
  
    // Return whether we found this object by searching a directory.
    bool
    searched_for() const
    { return this->input_file()->will_search_for(); }
  
    bool
    no_export() const
    { return this->no_export_; }
  
    void
    set_no_export(bool value)
    { this->no_export_ = value; }
  
    bool
    section_is_compressed(unsigned int shndx,
  			section_size_type* uncompressed_size,
  			elfcpp::Elf_Xword* palign = NULL) const
    {
      if (this->compressed_sections_ == NULL)
        return false;
      Compressed_section_map::const_iterator p =
          this->compressed_sections_->find(shndx);
      if (p != this->compressed_sections_->end())
        {
  	if (uncompressed_size != NULL)
  	  *uncompressed_size = p->second.size;
  	if (palign != NULL)
  	  *palign = p->second.addralign;
  	return true;
        }
      return false;
    }
  
    // Return a view of the decompressed contents of a section.  Set *PLEN
    // to the size.  Set *IS_NEW to true if the contents need to be freed
    // by the caller.
    const unsigned char*
    decompressed_section_contents(unsigned int shndx, section_size_type* plen,
  				bool* is_cached, uint64_t* palign = NULL);
  
    // Discard any buffers of decompressed sections.  This is done
    // at the end of the Add_symbols task.
    void
    discard_decompressed_sections();
  
    // Return the index of the first incremental relocation for symbol SYMNDX.
    unsigned int
    get_incremental_reloc_base(unsigned int symndx) const
    { return this->do_get_incremental_reloc_base(symndx); }
  
    // Return the number of incremental relocations for symbol SYMNDX.
    unsigned int
    get_incremental_reloc_count(unsigned int symndx) const
    { return this->do_get_incremental_reloc_count(symndx); }
  
    // Return the output view for section SHNDX.
    unsigned char*
    get_output_view(unsigned int shndx, section_size_type* plen) const
    { return this->do_get_output_view(shndx, plen); }
  
   protected:
    // Returns NULL for Objects that are not dynamic objects.  This method
    // is overridden in the Dynobj class.
    virtual Dynobj*
    do_dynobj()
    { return NULL; }
  
    // Returns NULL for Objects that are not plugin objects.  This method
    // is overridden in the Pluginobj class.
    virtual Pluginobj*
    do_pluginobj()
    { return NULL; }
  
    // Return TRUE if this is an incremental (unchanged) input file.
    // We return FALSE by default; the incremental object classes
    // override this method.
    virtual bool
    do_is_incremental() const
    { return false; }
  
    // Return the last modified time of the file.  This method may be
    // overridden for subclasses that don't use an actual file (e.g.,
    // Incremental objects).
    virtual Timespec
    do_get_mtime()
    { return this->input_file()->file().get_mtime(); }
  
    // Read the symbols--implemented by child class.
    virtual void
    do_read_symbols(Read_symbols_data*) = 0;
  
    // Lay out sections--implemented by child class.
    virtual void
    do_layout(Symbol_table*, Layout*, Read_symbols_data*) = 0;
  
    // Add symbol information to the global symbol table--implemented by
    // child class.
    virtual void
    do_add_symbols(Symbol_table*, Read_symbols_data*, Layout*) = 0;
  
    virtual Archive::Should_include
    do_should_include_member(Symbol_table* symtab, Layout*, Read_symbols_data*,
                             std::string* why) = 0;
  
    // Iterate over global symbols, calling a visitor class V for each.
    virtual void
    do_for_all_global_symbols(Read_symbols_data* sd,
  			    Library_base::Symbol_visitor_base* v) = 0;
  
    // Iterate over local symbols, calling a visitor class V for each GOT offset
    // associated with a local symbol.
    virtual void
    do_for_all_local_got_entries(Got_offset_list::Visitor* v) const = 0;
  
    // Return the location of the contents of a section.  Implemented by
    // child class.
    virtual const unsigned char*
    do_section_contents(unsigned int shndx, section_size_type* plen,
  		      bool cache) = 0;
  
    // Get the size of a section--implemented by child class.
    virtual uint64_t
    do_section_size(unsigned int shndx) = 0;
  
    // Get the name of a section--implemented by child class.
    virtual std::string
    do_section_name(unsigned int shndx) const = 0;
  
    // Get section flags--implemented by child class.
    virtual uint64_t
    do_section_flags(unsigned int shndx) = 0;
  
    // Get section entsize--implemented by child class.
    virtual uint64_t
    do_section_entsize(unsigned int shndx) = 0;
  
    // Get section address--implemented by child class.
    virtual uint64_t
    do_section_address(unsigned int shndx) = 0;
  
    // Get section type--implemented by child class.
    virtual unsigned int
    do_section_type(unsigned int shndx) = 0;
  
    // Get section link field--implemented by child class.
    virtual unsigned int
    do_section_link(unsigned int shndx) = 0;
  
    // Get section info field--implemented by child class.
    virtual unsigned int
    do_section_info(unsigned int shndx) = 0;
  
    // Get section alignment--implemented by child class.
    virtual uint64_t
    do_section_addralign(unsigned int shndx) = 0;
  
    // Return the output section given a section index--implemented
    // by child class.
    virtual Output_section*
    do_output_section(unsigned int) const
    { gold_unreachable(); }
  
    // Get the address of a section--implemented by child class.
    virtual uint64_t
    do_output_section_address(unsigned int)
    { gold_unreachable(); }
  
    // Get the offset of a section--implemented by child class.
    virtual uint64_t
    do_output_section_offset(unsigned int) const
    { gold_unreachable(); }
  
    // Return the Xindex structure to use.
    virtual Xindex*
    do_initialize_xindex() = 0;
  
    // Implement get_global_symbol_counts--implemented by child class.
    virtual void
    do_get_global_symbol_counts(const Symbol_table*, size_t*, size_t*) const = 0;
  
    virtual const Symbols*
    do_get_global_symbols() const = 0;
  
    // Set the number of sections.
    void
    set_shnum(int shnum)
    { this->shnum_ = shnum; }
  
    // Functions used by both Sized_relobj_file and Sized_dynobj.
  
    // Read the section data into a Read_symbols_data object.
    template<int size, bool big_endian>
    void
    read_section_data(elfcpp::Elf_file<size, big_endian, Object>*,
  		    Read_symbols_data*);
  
    // Find the section header with the given NAME.  If HDR is non-NULL
    // then it is a section header returned from a previous call to this
    // function and the next section header with the same name will be
    // returned.
    template<int size, bool big_endian>
    const unsigned char*
    find_shdr(const unsigned char* pshdrs, const char* name,
  	    const char* names, section_size_type names_size,
  	    const unsigned char* hdr) const;
  
    // Let the child class initialize the xindex object directly.
    void
    set_xindex(Xindex* xindex)
    {
      gold_assert(this->xindex_ == NULL);
      this->xindex_ = xindex;
    }
  
    // If NAME is the name of a special .gnu.warning section, arrange
    // for the warning to be issued.  SHNDX is the section index.
    // Return whether it is a warning section.
    bool
    handle_gnu_warning_section(const char* name, unsigned int shndx,
  			     Symbol_table*);
  
    // If NAME is the name of the special section which indicates that
    // this object was compiled with -fsplit-stack, mark it accordingly,
    // and return true.  Otherwise return false.
    bool
    handle_split_stack_section(const char* name);
  
    // Discard any buffers of decompressed sections.  This is done
    // at the end of the Add_symbols task.
    virtual void
    do_discard_decompressed_sections()
    { }
  
    // Return the index of the first incremental relocation for symbol SYMNDX--
    // implemented by child class.
    virtual unsigned int
    do_get_incremental_reloc_base(unsigned int) const
    { gold_unreachable(); }
  
    // Return the number of incremental relocations for symbol SYMNDX--
    // implemented by child class.
    virtual unsigned int
    do_get_incremental_reloc_count(unsigned int) const
    { gold_unreachable(); }
  
    // Return the output view for a section.
    virtual unsigned char*
    do_get_output_view(unsigned int, section_size_type*) const
    { gold_unreachable(); }
  
    void
    set_compressed_sections(Compressed_section_map* compressed_sections)
    { this->compressed_sections_ = compressed_sections; }
  
    Compressed_section_map*
    compressed_sections()
    { return this->compressed_sections_; }
  
   private:
    // This class may not be copied.
    Object(const Object&);
    Object& operator=(const Object&);
  
    // Name of object as printed to user.
    std::string name_;
    // For reading the file.
    Input_file* input_file_;
    // Offset within the file--0 for an object file, non-0 for an
    // archive.
    off_t offset_;
    // Number of input sections.
    unsigned int shnum_;
    // Whether this is a dynamic object.
    bool is_dynamic_ : 1;
    // Whether this object is needed.  This is only set for dynamic
    // objects, and means that the object defined a symbol which was
    // used by a reference from a regular object.
    bool is_needed_ : 1;
    // Whether this object was compiled with -fsplit-stack.
    bool uses_split_stack_ : 1;
    // Whether this object contains any functions compiled with the
    // no_split_stack attribute.
    bool has_no_split_stack_ : 1;
    // True if exclude this object from automatic symbol export.
    // This is used only for archive objects.
    bool no_export_ : 1;
    // True if the object was found in a system directory.
    bool is_in_system_directory_ : 1;
    // True if the object was linked with --as-needed.
    bool as_needed_ : 1;
    // Many sections for objects with more than SHN_LORESERVE sections.
    Xindex* xindex_;
    // For compressed debug sections, map section index to uncompressed size
    // and contents.
    Compressed_section_map* compressed_sections_;
  };
  
  // A regular object (ET_REL).  This is an abstract base class itself.
  // The implementation is the template class Sized_relobj_file.
  
  class Relobj : public Object
  {
   public:
    Relobj(const std::string& name, Input_file* input_file, off_t offset = 0)
      : Object(name, input_file, false, offset),
        output_sections_(),
        map_to_relocatable_relocs_(NULL),
        object_merge_map_(NULL),
        relocs_must_follow_section_writes_(false),
        sd_(NULL),
        reloc_counts_(NULL),
        reloc_bases_(NULL),
        first_dyn_reloc_(0),
        dyn_reloc_count_(0)
    { }
  
    // During garbage collection, the Read_symbols_data pass for 
    // each object is stored as layout needs to be done after 
    // reloc processing.
    Symbols_data* 
    get_symbols_data()
    { return this->sd_; }
  
    // Decides which section names have to be included in the worklist
    // as roots.
    bool
    is_section_name_included(const char* name);
   
    void
    copy_symbols_data(Symbols_data* gc_sd, Read_symbols_data* sd,
                      unsigned int section_header_size);
  
    void
    set_symbols_data(Symbols_data* sd)
    { this->sd_ = sd; }
  
    // During garbage collection, the Read_relocs pass for all objects 
    // is done before scanning the relocs.  In that case, this->rd_ is
    // used to store the information from Read_relocs for each object.
    // This data is also used to compute the list of relevant sections.
    Read_relocs_data*
    get_relocs_data()
    { return this->rd_; }
  
    void
    set_relocs_data(Read_relocs_data* rd)
    { this->rd_ = rd; }
  
    virtual bool
    is_output_section_offset_invalid(unsigned int shndx) const = 0;
  
    // Read the relocs.
    void
    read_relocs(Read_relocs_data* rd)
    { return this->do_read_relocs(rd); }
  
    // Process the relocs, during garbage collection only.
    void
    gc_process_relocs(Symbol_table* symtab, Layout* layout, Read_relocs_data* rd)
    { return this->do_gc_process_relocs(symtab, layout, rd); }
  
    // Scan the relocs and adjust the symbol table.
    void
    scan_relocs(Symbol_table* symtab, Layout* layout, Read_relocs_data* rd)
    { return this->do_scan_relocs(symtab, layout, rd); }
  
    // Return the value of the local symbol whose index is SYMNDX, plus
    // ADDEND.  ADDEND is passed in so that we can correctly handle the
    // section symbol for a merge section.
    uint64_t
    local_symbol_value(unsigned int symndx, uint64_t addend) const
    { return this->do_local_symbol_value(symndx, addend); }
  
    // Return the PLT offset for a local symbol.  It is an error to call
    // this if it doesn't have one.
    unsigned int
    local_plt_offset(unsigned int symndx) const
    { return this->do_local_plt_offset(symndx); }
  
    // Return whether the local symbol SYMNDX has a GOT offset of type
    // GOT_TYPE.
    bool
    local_has_got_offset(unsigned int symndx, unsigned int got_type) const
    { return this->do_local_has_got_offset(symndx, got_type, 0); }
  
    // Return whether the local symbol SYMNDX plus ADDEND has a GOT offset
    // of type GOT_TYPE.
    bool
    local_has_got_offset(unsigned int symndx, unsigned int got_type,
  		       uint64_t addend) const
    { return this->do_local_has_got_offset(symndx, got_type, addend); }
  
    // Return the GOT offset of type GOT_TYPE of the local symbol
    // SYMNDX.  It is an error to call this if the symbol does not have
    // a GOT offset of the specified type.
    unsigned int
    local_got_offset(unsigned int symndx, unsigned int got_type) const
    { return this->do_local_got_offset(symndx, got_type, 0); }
  
    // Return the GOT offset of type GOT_TYPE of the local symbol
    // SYMNDX plus ADDEND.  It is an error to call this if the symbol
    // does not have a GOT offset of the specified type.
    unsigned int
    local_got_offset(unsigned int symndx, unsigned int got_type,
  		       uint64_t addend) const
    { return this->do_local_got_offset(symndx, got_type, addend); }
  
    // Set the GOT offset with type GOT_TYPE of the local symbol SYMNDX
    // to GOT_OFFSET.
    void
    set_local_got_offset(unsigned int symndx, unsigned int got_type,
  		       unsigned int got_offset)
    { this->do_set_local_got_offset(symndx, got_type, got_offset, 0); }
  
    // Set the GOT offset with type GOT_TYPE of the local symbol SYMNDX
    // plus ADDEND to GOT_OFFSET.
    void
    set_local_got_offset(unsigned int symndx, unsigned int got_type,
  		       unsigned int got_offset, uint64_t addend)
    { this->do_set_local_got_offset(symndx, got_type, got_offset, addend); }
  
    // Return whether the local symbol SYMNDX is a TLS symbol.
    bool
    local_is_tls(unsigned int symndx) const
    { return this->do_local_is_tls(symndx); }
  
    // The number of local symbols in the input symbol table.
    virtual unsigned int
    local_symbol_count() const
    { return this->do_local_symbol_count(); }
  
    // The number of local symbols in the output symbol table.
    virtual unsigned int
    output_local_symbol_count() const
    { return this->do_output_local_symbol_count(); }
  
    // The file offset for local symbols in the output symbol table.
    virtual off_t
    local_symbol_offset() const
    { return this->do_local_symbol_offset(); }
  
    // Initial local symbol processing: count the number of local symbols
    // in the output symbol table and dynamic symbol table; add local symbol
    // names to *POOL and *DYNPOOL.
    void
    count_local_symbols(Stringpool_template<char>* pool,
                        Stringpool_template<char>* dynpool)
    { return this->do_count_local_symbols(pool, dynpool); }
  
    // Set the values of the local symbols, set the output symbol table
    // indexes for the local variables, and set the offset where local
    // symbol information will be stored. Returns the new local symbol index.
    unsigned int
    finalize_local_symbols(unsigned int index, off_t off, Symbol_table* symtab)
    { return this->do_finalize_local_symbols(index, off, symtab); }
  
    // Set the output dynamic symbol table indexes for the local variables.
    unsigned int
    set_local_dynsym_indexes(unsigned int index)
    { return this->do_set_local_dynsym_indexes(index); }
  
    // Set the offset where local dynamic symbol information will be stored.
    unsigned int
    set_local_dynsym_offset(off_t off)
    { return this->do_set_local_dynsym_offset(off); }
  
    // Record a dynamic relocation against an input section from this object.
    void
    add_dyn_reloc(unsigned int index)
    {
      if (this->dyn_reloc_count_ == 0)
        this->first_dyn_reloc_ = index;
      ++this->dyn_reloc_count_;
    }
  
    // Return the index of the first dynamic relocation.
    unsigned int
    first_dyn_reloc() const
    { return this->first_dyn_reloc_; }
  
    // Return the count of dynamic relocations.
    unsigned int
    dyn_reloc_count() const
    { return this->dyn_reloc_count_; }
  
    // Relocate the input sections and write out the local symbols.
    void
    relocate(const Symbol_table* symtab, const Layout* layout, Output_file* of)
    { return this->do_relocate(symtab, layout, of); }
  
    // Return whether an input section is being included in the link.
    bool
    is_section_included(unsigned int shndx) const
    {
      gold_assert(shndx < this->output_sections_.size());
      return this->output_sections_[shndx] != NULL;
    }
  
    // The output section of the input section with index SHNDX.
    // This is only used currently to remove a section from the link in
    // relaxation.
    void
    set_output_section(unsigned int shndx, Output_section* os)
    {
      gold_assert(shndx < this->output_sections_.size());
      this->output_sections_[shndx] = os;
    }
    
    // Set the offset of an input section within its output section.
    void
    set_section_offset(unsigned int shndx, uint64_t off)
    { this->do_set_section_offset(shndx, off); }
  
    // Return true if we need to wait for output sections to be written
    // before we can apply relocations.  This is true if the object has
    // any relocations for sections which require special handling, such
    // as the exception frame section.
    bool
    relocs_must_follow_section_writes() const
    { return this->relocs_must_follow_section_writes_; }
  
    Object_merge_map*
    get_or_create_merge_map();
  
    template<int size>
    void
    initialize_input_to_output_map(unsigned int shndx,
        typename elfcpp::Elf_types<size>::Elf_Addr starting_address,
        Unordered_map<section_offset_type,
  	    typename elfcpp::Elf_types<size>::Elf_Addr>* output_address) const;
  
    void
    add_merge_mapping(Output_section_data *output_data,
                      unsigned int shndx, section_offset_type offset,
                      section_size_type length,
                      section_offset_type output_offset);
  
    bool
    merge_output_offset(unsigned int shndx, section_offset_type offset,
                        section_offset_type *poutput) const;
  
    const Output_section_data*
    find_merge_section(unsigned int shndx) const;
  
    // Record the relocatable reloc info for an input reloc section.
    void
    set_relocatable_relocs(unsigned int reloc_shndx, Relocatable_relocs* rr)
    {
      gold_assert(reloc_shndx < this->shnum());
      (*this->map_to_relocatable_relocs_)[reloc_shndx] = rr;
    }
  
    // Get the relocatable reloc info for an input reloc section.
    Relocatable_relocs*
    relocatable_relocs(unsigned int reloc_shndx)
    {
      gold_assert(reloc_shndx < this->shnum());
      return (*this->map_to_relocatable_relocs_)[reloc_shndx];
    }
  
    // Layout sections whose layout was deferred while waiting for
    // input files from a plugin.
    void
    layout_deferred_sections(Layout* layout)
    { this->do_layout_deferred_sections(layout); }
  
    // Return the index of the first incremental relocation for symbol SYMNDX.
    virtual unsigned int
    do_get_incremental_reloc_base(unsigned int symndx) const
    { return this->reloc_bases_[symndx]; }
  
    // Return the number of incremental relocations for symbol SYMNDX.
    virtual unsigned int
    do_get_incremental_reloc_count(unsigned int symndx) const
    { return this->reloc_counts_[symndx]; }
  
    // Return the word size of the object file.
    int
    elfsize() const
    { return this->do_elfsize(); }
  
    // Return TRUE if this is a big-endian object file.
    bool
    is_big_endian() const
    { return this->do_is_big_endian(); }
  
   protected:
    // The output section to be used for each input section, indexed by
    // the input section number.  The output section is NULL if the
    // input section is to be discarded.
    typedef std::vector<Output_section*> Output_sections;
  
    // Read the relocs--implemented by child class.
    virtual void
    do_read_relocs(Read_relocs_data*) = 0;
  
    // Process the relocs--implemented by child class.
    virtual void
    do_gc_process_relocs(Symbol_table*, Layout*, Read_relocs_data*) = 0;
  
    // Scan the relocs--implemented by child class.
    virtual void
    do_scan_relocs(Symbol_table*, Layout*, Read_relocs_data*) = 0;
  
    // Return the value of a local symbol.
    virtual uint64_t
    do_local_symbol_value(unsigned int symndx, uint64_t addend) const = 0;
  
    // Return the PLT offset of a local symbol.
    virtual unsigned int
    do_local_plt_offset(unsigned int symndx) const = 0;
  
    // Return whether a local symbol plus addend has a GOT offset
    // of a given type.
    virtual bool
    do_local_has_got_offset(unsigned int symndx,
  			  unsigned int got_type, uint64_t addend) const = 0;
  
    // Return the GOT offset of a given type of a local symbol plus addend.
    virtual unsigned int
    do_local_got_offset(unsigned int symndx, unsigned int got_type,
  		      uint64_t addend) const = 0;
  
    // Set the GOT offset with a given type for a local symbol plus addend.
    virtual void
    do_set_local_got_offset(unsigned int symndx, unsigned int got_type,
  			  unsigned int got_offset, uint64_t addend) = 0;
  
    // Return whether local symbol SYMNDX is a TLS symbol.
    virtual bool
    do_local_is_tls(unsigned int symndx) const = 0;
  
    // Return the number of local symbols--implemented by child class.
    virtual unsigned int
    do_local_symbol_count() const = 0;
  
    // Return the number of output local symbols--implemented by child class.
    virtual unsigned int
    do_output_local_symbol_count() const = 0;
  
    // Return the file offset for local symbols--implemented by child class.
    virtual off_t
    do_local_symbol_offset() const = 0;
  
    // Count local symbols--implemented by child class.
    virtual void
    do_count_local_symbols(Stringpool_template<char>*,
  			 Stringpool_template<char>*) = 0;
  
    // Finalize the local symbols.  Set the output symbol table indexes
    // for the local variables, and set the offset where local symbol
    // information will be stored.
    virtual unsigned int
    do_finalize_local_symbols(unsigned int, off_t, Symbol_table*) = 0;
  
    // Set the output dynamic symbol table indexes for the local variables.
    virtual unsigned int
    do_set_local_dynsym_indexes(unsigned int) = 0;
  
    // Set the offset where local dynamic symbol information will be stored.
    virtual unsigned int
    do_set_local_dynsym_offset(off_t) = 0;
  
    // Relocate the input sections and write out the local
    // symbols--implemented by child class.
    virtual void
    do_relocate(const Symbol_table* symtab, const Layout*, Output_file* of) = 0;
  
    // Set the offset of a section--implemented by child class.
    virtual void
    do_set_section_offset(unsigned int shndx, uint64_t off) = 0;
  
    // Layout sections whose layout was deferred while waiting for
    // input files from a plugin--implemented by child class.
    virtual void
    do_layout_deferred_sections(Layout*) = 0;
  
    // Given a section index, return the corresponding Output_section.
    // The return value will be NULL if the section is not included in
    // the link.
    Output_section*
    do_output_section(unsigned int shndx) const
    {
      gold_assert(shndx < this->output_sections_.size());
      return this->output_sections_[shndx];
    }
  
    // Return the vector mapping input sections to output sections.
    Output_sections&
    output_sections()
    { return this->output_sections_; }
  
    const Output_sections&
    output_sections() const
    { return this->output_sections_; }
  
    // Set the size of the relocatable relocs array.
    void
    size_relocatable_relocs()
    {
      this->map_to_relocatable_relocs_ =
        new std::vector<Relocatable_relocs*>(this->shnum());
    }
  
    // Record that we must wait for the output sections to be written
    // before applying relocations.
    void
    set_relocs_must_follow_section_writes()
    { this->relocs_must_follow_section_writes_ = true; }
  
    // Allocate the array for counting incremental relocations.
    void
    allocate_incremental_reloc_counts()
    {
      unsigned int nsyms = this->do_get_global_symbols()->size();
      this->reloc_counts_ = new unsigned int[nsyms];
      gold_assert(this->reloc_counts_ != NULL);
      memset(this->reloc_counts_, 0, nsyms * sizeof(unsigned int));
    }
  
    // Record a relocation in this object referencing global symbol SYMNDX.
    // Used for tracking incremental link information.
    void
    count_incremental_reloc(unsigned int symndx)
    {
      unsigned int nsyms = this->do_get_global_symbols()->size();
      gold_assert(symndx < nsyms);
      gold_assert(this->reloc_counts_ != NULL);
      ++this->reloc_counts_[symndx];
    }
  
    // Finalize the incremental relocation information.
    void
    finalize_incremental_relocs(Layout* layout, bool clear_counts);
  
    // Return the index of the next relocation to be written for global symbol
    // SYMNDX.  Only valid after finalize_incremental_relocs() has been called.
    unsigned int
    next_incremental_reloc_index(unsigned int symndx)
    {
      unsigned int nsyms = this->do_get_global_symbols()->size();
  
      gold_assert(this->reloc_counts_ != NULL);
      gold_assert(this->reloc_bases_ != NULL);
      gold_assert(symndx < nsyms);
  
      unsigned int counter = this->reloc_counts_[symndx]++;
      return this->reloc_bases_[symndx] + counter;
    }
  
    // Return the word size of the object file--
    // implemented by child class.
    virtual int
    do_elfsize() const = 0;
  
    // Return TRUE if this is a big-endian object file--
    // implemented by child class.
    virtual bool
    do_is_big_endian() const = 0;
  
   private:
    // Mapping from input sections to output section.
    Output_sections output_sections_;
    // Mapping from input section index to the information recorded for
    // the relocations.  This is only used for a relocatable link.
    std::vector<Relocatable_relocs*>* map_to_relocatable_relocs_;
    // Mappings for merge sections.  This is managed by the code in the
    // Merge_map class.
    Object_merge_map* object_merge_map_;
    // Whether we need to wait for output sections to be written before
    // we can apply relocations.
    bool relocs_must_follow_section_writes_;
    // Used to store the relocs data computed by the Read_relocs pass. 
    // Used during garbage collection of unused sections.
    Read_relocs_data* rd_;
    // Used to store the symbols data computed by the Read_symbols pass.
    // Again used during garbage collection when laying out referenced
    // sections.
    gold::Symbols_data* sd_;
    // Per-symbol counts of relocations, for incremental links.
    unsigned int* reloc_counts_;
    // Per-symbol base indexes of relocations, for incremental links.
    unsigned int* reloc_bases_;
    // Index of the first dynamic relocation for this object.
    unsigned int first_dyn_reloc_;
    // Count of dynamic relocations for this object.
    unsigned int dyn_reloc_count_;
  };
  
  // This class is used to handle relocations against a section symbol
  // in an SHF_MERGE section.  For such a symbol, we need to know the
  // addend of the relocation before we can determine the final value.
  // The addend gives us the location in the input section, and we can
  // determine how it is mapped to the output section.  For a
  // non-section symbol, we apply the addend to the final value of the
  // symbol; that is done in finalize_local_symbols, and does not use
  // this class.
  
  template<int size>
  class Merged_symbol_value
  {
   public:
    typedef typename elfcpp::Elf_types<size>::Elf_Addr Value;
  
    // We use a hash table to map offsets in the input section to output
    // addresses.
    typedef Unordered_map<section_offset_type, Value> Output_addresses;
  
    Merged_symbol_value(Value input_value, Value output_start_address)
      : input_value_(input_value), output_start_address_(output_start_address),
        output_addresses_()
    { }
  
    // Initialize the hash table.
    void
    initialize_input_to_output_map(const Relobj*, unsigned int input_shndx);
  
    // Release the hash table to save space.
    void
    free_input_to_output_map()
    { this->output_addresses_.clear(); }
  
    // Get the output value corresponding to an addend.  The object and
    // input section index are passed in because the caller will have
    // them; otherwise we could store them here.
    Value
    value(const Relobj* object, unsigned int input_shndx, Value addend) const
    {
      // This is a relocation against a section symbol.  ADDEND is the
      // offset in the section.  The result should be the start of some
      // merge area.  If the object file wants something else, it should
      // use a regular symbol rather than a section symbol.
      // Unfortunately, PR 6658 shows a case in which the object file
      // refers to the section symbol, but uses a negative ADDEND to
      // compensate for a PC relative reloc.  We can't handle the
      // general case.  However, we can handle the special case of a
      // negative addend, by assuming that it refers to the start of the
      // section.  Of course, that means that we have to guess when
      // ADDEND is negative.  It is normal to see a 32-bit value here
      // even when the template parameter size is 64, as 64-bit object
      // file formats have 32-bit relocations.  We know this is a merge
      // section, so we know it has to fit into memory.  So we assume
      // that we won't see a value larger than a large 32-bit unsigned
      // value.  This will break objects with very very large merge
      // sections; they probably break in other ways anyhow.
      Value input_offset = this->input_value_;
      if (addend < 0xffffff00)
        {
  	input_offset += addend;
  	addend = 0;
        }
      typename Output_addresses::const_iterator p =
        this->output_addresses_.find(input_offset);
      if (p != this->output_addresses_.end())
        return p->second + addend;
  
      return (this->value_from_output_section(object, input_shndx, input_offset)
  	    + addend);
    }
  
   private:
    // Get the output value for an input offset if we couldn't find it
    // in the hash table.
    Value
    value_from_output_section(const Relobj*, unsigned int input_shndx,
  			    Value input_offset) const;
  
    // The value of the section symbol in the input file.  This is
    // normally zero, but could in principle be something else.
    Value input_value_;
    // The start address of this merged section in the output file.
    Value output_start_address_;
    // A hash table which maps offsets in the input section to output
    // addresses.  This only maps specific offsets, not all offsets.
    Output_addresses output_addresses_;
  };
  
  // This POD class is holds the value of a symbol.  This is used for
  // local symbols, and for all symbols during relocation processing.
  // For special sections, such as SHF_MERGE sections, this calls a
  // function to get the final symbol value.
  
  template<int size>
  class Symbol_value
  {
   public:
    typedef typename elfcpp::Elf_types<size>::Elf_Addr Value;
  
    Symbol_value()
      : output_symtab_index_(0), output_dynsym_index_(-1U), input_shndx_(0),
        is_ordinary_shndx_(false), is_section_symbol_(false),
        is_tls_symbol_(false), is_ifunc_symbol_(false), has_output_value_(true)
    { this->u_.value = 0; }
  
    ~Symbol_value()
    {
      if (!this->has_output_value_)
        delete this->u_.merged_symbol_value;
    }
  
    // Get the value of this symbol.  OBJECT is the object in which this
    // symbol is defined, and ADDEND is an addend to add to the value.
    template<bool big_endian>
    Value
    value(const Sized_relobj_file<size, big_endian>* object, Value addend) const
    {
      if (this->has_output_value_)
        return this->u_.value + addend;
      else
        {
  	gold_assert(this->is_ordinary_shndx_);
  	return this->u_.merged_symbol_value->value(object, this->input_shndx_,
  						   addend);
        }
    }
  
    // Set the value of this symbol in the output symbol table.
    void
    set_output_value(Value value)
    { this->u_.value = value; }
  
    // For a section symbol in a merged section, we need more
    // information.
    void
    set_merged_symbol_value(Merged_symbol_value<size>* msv)
    {
      gold_assert(this->is_section_symbol_);
      this->has_output_value_ = false;
      this->u_.merged_symbol_value = msv;
    }
  
    // Initialize the input to output map for a section symbol in a
    // merged section.  We also initialize the value of a non-section
    // symbol in a merged section.
    void
    initialize_input_to_output_map(const Relobj* object)
    {
      if (!this->has_output_value_)
        {
  	gold_assert(this->is_section_symbol_ && this->is_ordinary_shndx_);
  	Merged_symbol_value<size>* msv = this->u_.merged_symbol_value;
  	msv->initialize_input_to_output_map(object, this->input_shndx_);
        }
    }
  
    // Free the input to output map for a section symbol in a merged
    // section.
    void
    free_input_to_output_map()
    {
      if (!this->has_output_value_)
        this->u_.merged_symbol_value->free_input_to_output_map();
    }
  
    // Set the value of the symbol from the input file.  This is only
    // called by count_local_symbols, to communicate the value to
    // finalize_local_symbols.
    void
    set_input_value(Value value)
    { this->u_.value = value; }
  
    // Return the input value.  This is only called by
    // finalize_local_symbols and (in special cases) relocate_section.
    Value
    input_value() const
    { return this->u_.value; }
  
    // Return whether we have set the index in the output symbol table
    // yet.
    bool
    is_output_symtab_index_set() const
    {
      return (this->output_symtab_index_ != 0
  	    && this->output_symtab_index_ != -2U);
    }
  
    // Return whether this symbol may be discarded from the normal
    // symbol table.
    bool
    may_be_discarded_from_output_symtab() const
    {
      gold_assert(!this->is_output_symtab_index_set());
      return this->output_symtab_index_ != -2U;
    }
  
    // Return whether this symbol has an entry in the output symbol
    // table.
    bool
    has_output_symtab_entry() const
    {
      gold_assert(this->is_output_symtab_index_set());
      return this->output_symtab_index_ != -1U;
    }
  
    // Return the index in the output symbol table.
    unsigned int
    output_symtab_index() const
    {
      gold_assert(this->is_output_symtab_index_set()
  		&& this->output_symtab_index_ != -1U);
      return this->output_symtab_index_;
    }
  
    // Set the index in the output symbol table.
    void
    set_output_symtab_index(unsigned int i)
    {
      gold_assert(!this->is_output_symtab_index_set());
      gold_assert(i != 0 && i != -1U && i != -2U);
      this->output_symtab_index_ = i;
    }
  
    // Record that this symbol should not go into the output symbol
    // table.
    void
    set_no_output_symtab_entry()
    {
      gold_assert(this->output_symtab_index_ == 0);
      this->output_symtab_index_ = -1U;
    }
  
    // Record that this symbol must go into the output symbol table,
    // because it there is a relocation that uses it.
    void
    set_must_have_output_symtab_entry()
    {
      gold_assert(!this->is_output_symtab_index_set());
      this->output_symtab_index_ = -2U;
    }
  
    // Set the index in the output dynamic symbol table.
    void
    set_needs_output_dynsym_entry()
    {
      gold_assert(!this->is_section_symbol());
      this->output_dynsym_index_ = 0;
    }
  
    // Return whether this symbol should go into the dynamic symbol
    // table.
    bool
    needs_output_dynsym_entry() const
    {
      return this->output_dynsym_index_ != -1U;
    }
  
    // Return whether this symbol has an entry in the dynamic symbol
    // table.
    bool
    has_output_dynsym_entry() const
    {
      gold_assert(this->output_dynsym_index_ != 0);
      return this->output_dynsym_index_ != -1U;
    }
  
    // Record that this symbol should go into the dynamic symbol table.
    void
    set_output_dynsym_index(unsigned int i)
    {
      gold_assert(this->output_dynsym_index_ == 0);
      gold_assert(i != 0 && i != -1U);
      this->output_dynsym_index_ = i;
    }
  
    // Return the index in the output dynamic symbol table.
    unsigned int
    output_dynsym_index() const
    {
      gold_assert(this->output_dynsym_index_ != 0
                  && this->output_dynsym_index_ != -1U);
      return this->output_dynsym_index_;
    }
  
    // Set the index of the input section in the input file.
    void
    set_input_shndx(unsigned int i, bool is_ordinary)
    {
      this->input_shndx_ = i;
      // input_shndx_ field is a bitfield, so make sure that the value
      // fits.
      gold_assert(this->input_shndx_ == i);
      this->is_ordinary_shndx_ = is_ordinary;
    }
  
    // Return the index of the input section in the input file.
    unsigned int
    input_shndx(bool* is_ordinary) const
    {
      *is_ordinary = this->is_ordinary_shndx_;
      return this->input_shndx_;
    }
  
    // Whether this is a section symbol.
    bool
    is_section_symbol() const
    { return this->is_section_symbol_; }
  
    // Record that this is a section symbol.
    void
    set_is_section_symbol()
    {
      gold_assert(!this->needs_output_dynsym_entry());
      this->is_section_symbol_ = true;
    }
  
    // Record that this is a TLS symbol.
    void
    set_is_tls_symbol()
    { this->is_tls_symbol_ = true; }
  
    // Return true if this is a TLS symbol.
    bool
    is_tls_symbol() const
    { return this->is_tls_symbol_; }
  
    // Record that this is an IFUNC symbol.
    void
    set_is_ifunc_symbol()
    { this->is_ifunc_symbol_ = true; }
  
    // Return true if this is an IFUNC symbol.
    bool
    is_ifunc_symbol() const
    { return this->is_ifunc_symbol_; }
  
    // Return true if this has output value.
    bool
    has_output_value() const
    { return this->has_output_value_; }
  
   private:
    // The index of this local symbol in the output symbol table.  This
    // will be 0 if no value has been assigned yet, and the symbol may
    // be omitted.  This will be -1U if the symbol should not go into
    // the symbol table.  This will be -2U if the symbol must go into
    // the symbol table, but no index has been assigned yet.
    unsigned int output_symtab_index_;
    // The index of this local symbol in the dynamic symbol table.  This
    // will be -1U if the symbol should not go into the symbol table.
    unsigned int output_dynsym_index_;
    // The section index in the input file in which this symbol is
    // defined.
    unsigned int input_shndx_ : 27;
    // Whether the section index is an ordinary index, not a special
    // value.
    bool is_ordinary_shndx_ : 1;
    // Whether this is a STT_SECTION symbol.
    bool is_section_symbol_ : 1;
    // Whether this is a STT_TLS symbol.
    bool is_tls_symbol_ : 1;
    // Whether this is a STT_GNU_IFUNC symbol.
    bool is_ifunc_symbol_ : 1;
    // Whether this symbol has a value for the output file.  This is
    // normally set to true during Layout::finalize, by
    // finalize_local_symbols.  It will be false for a section symbol in
    // a merge section, as for such symbols we can not determine the
    // value to use in a relocation until we see the addend.
    bool has_output_value_ : 1;
    union
    {
      // This is used if has_output_value_ is true.  Between
      // count_local_symbols and finalize_local_symbols, this is the
      // value in the input file.  After finalize_local_symbols, it is
      // the value in the output file.
      Value value;
      // This is used if has_output_value_ is false.  It points to the
      // information we need to get the value for a merge section.
      Merged_symbol_value<size>* merged_symbol_value;
    } u_;
  };
  
  // This type is used to modify relocations for -fsplit-stack.  It is
  // indexed by relocation index, and means that the relocation at that
  // index should use the symbol from the vector, rather than the one
  // indicated by the relocation.
  
  class Reloc_symbol_changes
  {
   public:
    Reloc_symbol_changes(size_t count)
      : vec_(count, NULL)
    { }
  
    void
    set(size_t i, Symbol* sym)
    { this->vec_[i] = sym; }
  
    const Symbol*
    operator[](size_t i) const
    { return this->vec_[i]; }
  
   private:
    std::vector<Symbol*> vec_;
  };
  
  // Abstract base class for a regular object file, either a real object file
  // or an incremental (unchanged) object.  This is size and endian specific.
  
  template<int size, bool big_endian>
  class Sized_relobj : public Relobj
  {
   public:
    typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
    typedef Relobj::Symbols Symbols;
  
    static const Address invalid_address = static_cast<Address>(0) - 1;
  
    Sized_relobj(const std::string& name, Input_file* input_file)
      : Relobj(name, input_file), local_got_offsets_(), section_offsets_()
    { }
  
    Sized_relobj(const std::string& name, Input_file* input_file,
  		    off_t offset)
      : Relobj(name, input_file, offset), local_got_offsets_(), section_offsets_()
    { }
  
    ~Sized_relobj()
    { }
  
    // If this is a regular object, return a pointer to the Sized_relobj_file
    // object.  Otherwise, return NULL.
    virtual Sized_relobj_file<size, big_endian>*
    sized_relobj()
    { return NULL; }
  
    const virtual Sized_relobj_file<size, big_endian>*
    sized_relobj() const
    { return NULL; }
  
    // Checks if the offset of input section SHNDX within its output
    // section is invalid.
    bool
    is_output_section_offset_invalid(unsigned int shndx) const
    { return this->get_output_section_offset(shndx) == invalid_address; }
  
    // Get the offset of input section SHNDX within its output section.
    // This is -1 if the input section requires a special mapping, such
    // as a merge section.  The output section can be found in the
    // output_sections_ field of the parent class Relobj.
    Address
    get_output_section_offset(unsigned int shndx) const
    {
      gold_assert(shndx < this->section_offsets_.size());
      return this->section_offsets_[shndx];
    }
  
    // Iterate over local symbols, calling a visitor class V for each GOT offset
    // associated with a local symbol.
    void
    do_for_all_local_got_entries(Got_offset_list::Visitor* v) const;
  
   protected:
    typedef Relobj::Output_sections Output_sections;
  
    // Clear the local symbol information.
    void
    clear_got_offsets()
    { this->local_got_offsets_.clear(); }
  
    // Return the vector of section offsets.
    std::vector<Address>&
    section_offsets()
    { return this->section_offsets_; }
  
    // Get the address of an output section.
    uint64_t
    do_output_section_address(unsigned int shndx);
  
    // Get the offset of a section.
    uint64_t
    do_output_section_offset(unsigned int shndx) const
    {
      Address off = this->get_output_section_offset(shndx);
      if (off == invalid_address)
        return -1ULL;
      return off;
    }
  
    // Set the offset of a section.
    void
    do_set_section_offset(unsigned int shndx, uint64_t off)
    {
      gold_assert(shndx < this->section_offsets_.size());
      this->section_offsets_[shndx] =
        (off == static_cast<uint64_t>(-1)
         ? invalid_address
         : convert_types<Address, uint64_t>(off));
    }
  
    // Return whether the local symbol SYMNDX plus ADDEND has a GOT offset
    // of type GOT_TYPE.
    bool
    do_local_has_got_offset(unsigned int symndx, unsigned int got_type,
  			  uint64_t addend) const
    {
      Local_got_entry_key key(symndx, addend);
      Local_got_offsets::const_iterator p =
          this->local_got_offsets_.find(key);
      return (p != this->local_got_offsets_.end()
              && p->second->get_offset(got_type) != -1U);
    }
  
    // Return the GOT offset of type GOT_TYPE of the local symbol
    // SYMNDX plus ADDEND.
    unsigned int
    do_local_got_offset(unsigned int symndx, unsigned int got_type,
  			  uint64_t addend) const
    {
      Local_got_entry_key key(symndx, addend);
      Local_got_offsets::const_iterator p =
          this->local_got_offsets_.find(key);
      gold_assert(p != this->local_got_offsets_.end());
      unsigned int off = p->second->get_offset(got_type);
      gold_assert(off != -1U);
      return off;
    }
  
    // Set the GOT offset with type GOT_TYPE of the local symbol SYMNDX
    // plus ADDEND to GOT_OFFSET.
    void
    do_set_local_got_offset(unsigned int symndx, unsigned int got_type,
  			  unsigned int got_offset, uint64_t addend)
    {
      Local_got_entry_key key(symndx, addend);
      Local_got_offsets::const_iterator p =
          this->local_got_offsets_.find(key);
      if (p != this->local_got_offsets_.end())
        p->second->set_offset(got_type, got_offset);
      else
        {
          Got_offset_list* g = new Got_offset_list(got_type, got_offset);
          std::pair<Local_got_offsets::iterator, bool> ins =
              this->local_got_offsets_.insert(std::make_pair(key, g));
          gold_assert(ins.second);
        }
    }
  
    // Return the word size of the object file.
    virtual int
    do_elfsize() const
    { return size; }
  
    // Return TRUE if this is a big-endian object file.
    virtual bool
    do_is_big_endian() const
    { return big_endian; }
  
   private:
    // The GOT offsets of local symbols. This map also stores GOT offsets
    // for tp-relative offsets for TLS symbols.
    typedef Unordered_map<Local_got_entry_key, Got_offset_list*,
                          Local_got_entry_key::hash,
                          Local_got_entry_key::equal_to> Local_got_offsets;
  
    // GOT offsets for local non-TLS symbols, and tp-relative offsets
    // for TLS symbols, indexed by local got entry key class.
    Local_got_offsets local_got_offsets_;
    // For each input section, the offset of the input section in its
    // output section.  This is INVALID_ADDRESS if the input section requires a
    // special mapping.
    std::vector<Address> section_offsets_;
  };
  
  // A regular object file.  This is size and endian specific.
  
  template<int size, bool big_endian>
  class Sized_relobj_file : public Sized_relobj<size, big_endian>
  {
   public:
    typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
    typedef typename Sized_relobj<size, big_endian>::Symbols Symbols;
    typedef std::vector<Symbol_value<size> > Local_values;
  
    static const Address invalid_address = static_cast<Address>(0) - 1;
  
    enum Compute_final_local_value_status
    {
      // No error.
      CFLV_OK,
      // An error occurred.
      CFLV_ERROR,
      // The local symbol has no output section.
      CFLV_DISCARDED
    };
  
    Sized_relobj_file(const std::string& name,
  		    Input_file* input_file,
  		    off_t offset,
  		    const typename elfcpp::Ehdr<size, big_endian>&);
  
    ~Sized_relobj_file();
  
    // Set up the object file based on TARGET.
    void
    setup()
    { this->do_setup(); }
  
    // Return a pointer to the Sized_relobj_file object.
    Sized_relobj_file<size, big_endian>*
    sized_relobj()
    { return this; }
  
    const Sized_relobj_file<size, big_endian>*
    sized_relobj() const
    { return this; }
  
    // Return the ELF file type.
    int
    e_type() const
    { return this->e_type_; }
  
    // Return the number of symbols.  This is only valid after
    // Object::add_symbols has been called.
    unsigned int
    symbol_count() const
    { return this->local_symbol_count_ + this->symbols_.size(); }
  
    // If SYM is the index of a global symbol in the object file's
    // symbol table, return the Symbol object.  Otherwise, return NULL.
    Symbol*
    global_symbol(unsigned int sym) const
    {
      if (sym >= this->local_symbol_count_)
        {
  	gold_assert(sym - this->local_symbol_count_ < this->symbols_.size());
  	return this->symbols_[sym - this->local_symbol_count_];
        }
      return NULL;
    }
  
    // Return the section index of symbol SYM.  Set *VALUE to its value
    // in the object file.  Set *IS_ORDINARY if this is an ordinary
    // section index, not a special code between SHN_LORESERVE and
    // SHN_HIRESERVE.  Note that for a symbol which is not defined in
    // this object file, this will set *VALUE to 0 and return SHN_UNDEF;
    // it will not return the final value of the symbol in the link.
    unsigned int
    symbol_section_and_value(unsigned int sym, Address* value, bool* is_ordinary);
  
    // Return a pointer to the Symbol_value structure which holds the
    // value of a local symbol.
    const Symbol_value<size>*
    local_symbol(unsigned int sym) const
    {
      gold_assert(sym < this->local_values_.size());
      return &this->local_values_[sym];
    }
  
    // Return the index of local symbol SYM in the ordinary symbol
    // table.  A value of -1U means that the symbol is not being output.
    unsigned int
    symtab_index(unsigned int sym) const
    {
      gold_assert(sym < this->local_values_.size());
      return this->local_values_[sym].output_symtab_index();
    }
  
    // Return the index of local symbol SYM in the dynamic symbol
    // table.  A value of -1U means that the symbol is not being output.
    unsigned int
    dynsym_index(unsigned int sym) const
    {
      gold_assert(sym < this->local_values_.size());
      return this->local_values_[sym].output_dynsym_index();
    }
  
    // Return the input section index of local symbol SYM.
    unsigned int
    local_symbol_input_shndx(unsigned int sym, bool* is_ordinary) const
    {
      gold_assert(sym < this->local_values_.size());
      return this->local_values_[sym].input_shndx(is_ordinary);
    }
  
    // Record that local symbol SYM must be in the output symbol table.
    void
    set_must_have_output_symtab_entry(unsigned int sym)
    {
      gold_assert(sym < this->local_values_.size());
      this->local_values_[sym].set_must_have_output_symtab_entry();
    }
  
    // Record that local symbol SYM needs a dynamic symbol entry.
    void
    set_needs_output_dynsym_entry(unsigned int sym)
    {
      gold_assert(sym < this->local_values_.size());
      this->local_values_[sym].set_needs_output_dynsym_entry();
    }
  
    // Return whether the local symbol SYMNDX has a PLT offset.
    bool
    local_has_plt_offset(unsigned int symndx) const;
  
    // Set the PLT offset of the local symbol SYMNDX.
    void
    set_local_plt_offset(unsigned int symndx, unsigned int plt_offset);
  
    // Adjust this local symbol value.  Return false if the symbol
    // should be discarded from the output file.
    bool
    adjust_local_symbol(Symbol_value<size>* lv) const
    { return this->do_adjust_local_symbol(lv); }
  
    // Return the name of the symbol that spans the given offset in the
    // specified section in this object.  This is used only for error
    // messages and is not particularly efficient.
    bool
    get_symbol_location_info(unsigned int shndx, off_t offset,
  			   Symbol_location_info* info);
  
    // Look for a kept section corresponding to the given discarded section,
    // and return its output address.  This is used only for relocations in
    // debugging sections.
    Address
    map_to_kept_section(unsigned int shndx, std::string& section_name,
  		      bool* found) const;
  
    // Look for a kept section corresponding to the given discarded section,
    // and return its object file.
    Relobj*
    find_kept_section_object(unsigned int shndx, unsigned int* symndx_p) const;
  
    // Return the name of symbol SYMNDX.
    const char*
    get_symbol_name(unsigned int symndx);
  
    // Compute final local symbol value.  R_SYM is the local symbol index.
    // LV_IN points to a local symbol value containing the input value.
    // LV_OUT points to a local symbol value storing the final output value,
    // which must not be a merged symbol value since before calling this
    // method to avoid memory leak.  SYMTAB points to a symbol table.
    //
    // The method returns a status code at return.  If the return status is
    // CFLV_OK, *LV_OUT contains the final value.  If the return status is
    // CFLV_ERROR, *LV_OUT is 0.  If the return status is CFLV_DISCARDED,
    // *LV_OUT is not modified.
    Compute_final_local_value_status
    compute_final_local_value(unsigned int r_sym,
  			    const Symbol_value<size>* lv_in,
  			    Symbol_value<size>* lv_out,
  			    const Symbol_table* symtab);
  
    // Return true if the layout for this object was deferred.
    bool is_deferred_layout() const
    { return this->is_deferred_layout_; }
  
   protected:
    typedef typename Sized_relobj<size, big_endian>::Output_sections
        Output_sections;
  
    // Set up.
    virtual void
    do_setup();
  
    // Read the symbols.
    void
    do_read_symbols(Read_symbols_data*);
  
    // Read the symbols.  This is common code for all target-specific
    // overrides of do_read_symbols.
    void
    base_read_symbols(Read_symbols_data*);
  
    // Return the value of a local symbol.
    uint64_t
    do_local_symbol_value(unsigned int symndx, uint64_t addend) const
    {
      const Symbol_value<size>* symval = this->local_symbol(symndx);
      return symval->value(this, addend);
    }
  
    // Return the PLT offset for a local symbol.  It is an error to call
    // this if it doesn't have one.
    unsigned int
    do_local_plt_offset(unsigned int symndx) const;
  
    // Return whether local symbol SYMNDX is a TLS symbol.
    bool
    do_local_is_tls(unsigned int symndx) const
    { return this->local_symbol(symndx)->is_tls_symbol(); }
  
    // Return the number of local symbols.
    unsigned int
    do_local_symbol_count() const
    { return this->local_symbol_count_; }
  
    // Return the number of local symbols in the output symbol table.
    unsigned int
    do_output_local_symbol_count() const
    { return this->output_local_symbol_count_; }
  
    // Return the number of local symbols in the output symbol table.
    off_t
    do_local_symbol_offset() const
    { return this->local_symbol_offset_; }
  
    // Lay out the input sections.
    void
    do_layout(Symbol_table*, Layout*, Read_symbols_data*);
  
    // Layout sections whose layout was deferred while waiting for
    // input files from a plugin.
    void
    do_layout_deferred_sections(Layout*);
  
    // Add the symbols to the symbol table.
    void
    do_add_symbols(Symbol_table*, Read_symbols_data*, Layout*);
  
    Archive::Should_include
    do_should_include_member(Symbol_table* symtab, Layout*, Read_symbols_data*,
                             std::string* why);
  
    // Iterate over global symbols, calling a visitor class V for each.
    void
    do_for_all_global_symbols(Read_symbols_data* sd,
  			    Library_base::Symbol_visitor_base* v);
  
    // Read the relocs.
    void
    do_read_relocs(Read_relocs_data*);
  
    // Process the relocs to find list of referenced sections. Used only
    // during garbage collection.
    void
    do_gc_process_relocs(Symbol_table*, Layout*, Read_relocs_data*);
  
    // Scan the relocs and adjust the symbol table.
    void
    do_scan_relocs(Symbol_table*, Layout*, Read_relocs_data*);
  
    // Count the local symbols.
    void
    do_count_local_symbols(Stringpool_template<char>*,
                              Stringpool_template<char>*);
  
    // Finalize the local symbols.
    unsigned int
    do_finalize_local_symbols(unsigned int, off_t, Symbol_table*);
  
    // Set the offset where local dynamic symbol information will be stored.
    unsigned int
    do_set_local_dynsym_indexes(unsigned int);
  
    // Set the offset where local dynamic symbol information will be stored.
    unsigned int
    do_set_local_dynsym_offset(off_t);
  
    // Relocate the input sections and write out the local symbols.
    void
    do_relocate(const Symbol_table* symtab, const Layout*, Output_file* of);
  
    // Get the size of a section.
    uint64_t
    do_section_size(unsigned int shndx)
    { return this->elf_file_.section_size(shndx); }
  
    // Get the name of a section.
    std::string
    do_section_name(unsigned int shndx) const
    { return this->elf_file_.section_name(shndx); }
  
    // Return the location of the contents of a section.
    const unsigned char*
    do_section_contents(unsigned int shndx, section_size_type* plen,
  		      bool cache)
    {
      Object::Location loc(this->elf_file_.section_contents(shndx));
      *plen = convert_to_section_size_type(loc.data_size);
      if (*plen == 0)
        {
  	static const unsigned char empty[1] = { '\0' };
  	return empty;
        }
      return this->get_view(loc.file_offset, *plen, true, cache);
    }
  
    // Return section flags.
    uint64_t
    do_section_flags(unsigned int shndx);
  
    // Return section entsize.
    uint64_t
    do_section_entsize(unsigned int shndx);
  
    // Return section address.
    uint64_t
    do_section_address(unsigned int shndx)
    { return this->elf_file_.section_addr(shndx); }
  
    // Return section type.
    unsigned int
    do_section_type(unsigned int shndx)
    { return this->elf_file_.section_type(shndx); }
  
    // Return the section link field.
    unsigned int
    do_section_link(unsigned int shndx)
    { return this->elf_file_.section_link(shndx); }
  
    // Return the section info field.
    unsigned int
    do_section_info(unsigned int shndx)
    { return this->elf_file_.section_info(shndx); }
  
    // Return the section alignment.
    uint64_t
    do_section_addralign(unsigned int shndx)
    { return this->elf_file_.section_addralign(shndx); }
  
    // Return the Xindex structure to use.
    Xindex*
    do_initialize_xindex();
  
    // Get symbol counts.
    void
    do_get_global_symbol_counts(const Symbol_table*, size_t*, size_t*) const;
  
    // Get the global symbols.
    const Symbols*
    do_get_global_symbols() const
    { return &this->symbols_; }
  
    // Adjust a section index if necessary.
    unsigned int
    adjust_shndx(unsigned int shndx)
    {
      if (shndx >= elfcpp::SHN_LORESERVE)
        shndx += this->elf_file_.large_shndx_offset();
      return shndx;
    }
  
    // Initialize input to output maps for section symbols in merged
    // sections.
    void
    initialize_input_to_output_maps();
  
    // Free the input to output maps for section symbols in merged
    // sections.
    void
    free_input_to_output_maps();
  
    // Return symbol table section index.
    unsigned int
    symtab_shndx() const
    { return this->symtab_shndx_; }
  
    // Allow a child class to access the ELF file.
    elfcpp::Elf_file<size, big_endian, Object>*
    elf_file()
    { return &this->elf_file_; }
    
    // Allow a child class to access the local values.
    Local_values*
    local_values()
    { return &this->local_values_; }
  
    // Views and sizes when relocating.
    struct View_size
    {
      unsigned char* view;
      typename elfcpp::Elf_types<size>::Elf_Addr address;
      off_t offset;
      section_size_type view_size;
      bool is_input_output_view;
      bool is_postprocessing_view;
      bool is_ctors_reverse_view;
    };
  
    typedef std::vector<View_size> Views;
  
    // Stash away info for a number of special sections.
    // Return true if any of the sections found require local symbols to be read.
    virtual bool
    do_find_special_sections(Read_symbols_data* sd);
  
    // This may be overriden by a child class.
    virtual void
    do_relocate_sections(const Symbol_table* symtab, const Layout* layout,
  		       const unsigned char* pshdrs, Output_file* of,
  		       Views* pviews);
  
    // Relocate section data for a range of sections.
    void
    relocate_section_range(const Symbol_table* symtab, const Layout* layout,
  			 const unsigned char* pshdrs, Output_file* of,
  			 Views* pviews, unsigned int start_shndx,
  			 unsigned int end_shndx);
  
    // Adjust this local symbol value.  Return false if the symbol
    // should be discarded from the output file.
    virtual bool
    do_adjust_local_symbol(Symbol_value<size>*) const
    { return true; }
  
    // Allow a child to set output local symbol count.
    void
    set_output_local_symbol_count(unsigned int value)
    { this->output_local_symbol_count_ = value; }
  
    // Return the output view for a section.
    unsigned char*
    do_get_output_view(unsigned int, section_size_type*) const;
  
   private:
    // For convenience.
    typedef Sized_relobj_file<size, big_endian> This;
    static const int ehdr_size = elfcpp::Elf_sizes<size>::ehdr_size;
    static const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
    static const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
    typedef elfcpp::Shdr<size, big_endian> Shdr;
    typedef elfcpp::Shdr_write<size, big_endian> Shdr_write;
  
    // To keep track of discarded comdat sections, we need to map a member
    // section index to the object and section index of the corresponding
    // kept section.
    struct Kept_comdat_section
    {
      Kept_comdat_section(uint64_t a_sh_size, Kept_section* a_kept_section,
  			unsigned int a_symndx, bool a_is_comdat)
        : sh_size(a_sh_size), kept_section(a_kept_section),
  	symndx (a_symndx), is_comdat(a_is_comdat)
      { }
      uint64_t sh_size;		// Section size
      Kept_section* kept_section;	// Kept section info
      unsigned int symndx;	// Index of key symbol
      bool is_comdat;		// True if comdat group, false if linkonce
    };
    typedef std::map<unsigned int, Kept_comdat_section>
        Kept_comdat_section_table;
  
    // Find the SHT_SYMTAB section, given the section headers.
    void
    find_symtab(const unsigned char* pshdrs);
  
    // Return whether SHDR has the right flags for a GNU style exception
    // frame section.
    bool
    check_eh_frame_flags(const elfcpp::Shdr<size, big_endian>* shdr) const;
  
    // Return whether there is a section named .eh_frame which might be
    // a GNU style exception frame section.
    bool
    find_eh_frame(const unsigned char* pshdrs, const char* names,
  		section_size_type names_size) const;
  
    // Whether to include a section group in the link.
    bool
    include_section_group(Symbol_table*, Layout*, unsigned int, const char*,
  			const unsigned char*, const char*, section_size_type,
  			std::vector<bool>*);
  
    // Whether to include a linkonce section in the link.
    bool
    include_linkonce_section(Layout*, unsigned int, const char*,
  			   const elfcpp::Shdr<size, big_endian>&);
  
    // Layout an input section.
    void
    layout_section(Layout* layout, unsigned int shndx, const char* name,
                   const typename This::Shdr& shdr, unsigned int sh_type,
                   unsigned int reloc_shndx, unsigned int reloc_type);
  
    // Layout an input .eh_frame section.
    void
    layout_eh_frame_section(Layout* layout, const unsigned char* symbols_data,
  			  section_size_type symbols_size,
  			  const unsigned char* symbol_names_data,
  			  section_size_type symbol_names_size,
  			  unsigned int shndx, const typename This::Shdr&,
  			  unsigned int reloc_shndx, unsigned int reloc_type);
  
    // Layout an input .note.gnu.property section.
    void
    layout_gnu_property_section(Layout* layout, unsigned int shndx);
  
    // Write section data to the output file.  Record the views and
    // sizes in VIEWS for use when relocating.
    void
    write_sections(const Layout*, const unsigned char* pshdrs, Output_file*,
  		 Views*);
  
    // Relocate the sections in the output file.
    void
    relocate_sections(const Symbol_table* symtab, const Layout* layout,
  		    const unsigned char* pshdrs, Output_file* of,
  		    Views* pviews)
    { this->do_relocate_sections(symtab, layout, pshdrs, of, pviews); }
  
    // Reverse the words in a section.  Used for .ctors sections mapped
    // to .init_array sections.
    void
    reverse_words(unsigned char*, section_size_type);
  
    // Scan the input relocations for --emit-relocs.
    void
    emit_relocs_scan(Symbol_table*, Layout*, const unsigned char* plocal_syms,
  		   const Read_relocs_data::Relocs_list::iterator&);
  
    // Scan the input relocations for --emit-relocs, templatized on the
    // type of the relocation section.
    template<int sh_type>
    void
    emit_relocs_scan_reltype(Symbol_table*, Layout*,
  			   const unsigned char* plocal_syms,
  			   const Read_relocs_data::Relocs_list::iterator&,
  			   Relocatable_relocs*);
  
    // Scan the input relocations for --incremental.
    void
    incremental_relocs_scan(const Read_relocs_data::Relocs_list::iterator&);
  
    // Scan the input relocations for --incremental, templatized on the
    // type of the relocation section.
    template<int sh_type>
    void
    incremental_relocs_scan_reltype(
        const Read_relocs_data::Relocs_list::iterator&);
  
    void
    incremental_relocs_write(const Relocate_info<size, big_endian>*,
  			   unsigned int sh_type,
  			   const unsigned char* prelocs,
  			   size_t reloc_count,
  			   Output_section*,
  			   Address output_offset,
  			   Output_file*);
  
    template<int sh_type>
    void
    incremental_relocs_write_reltype(const Relocate_info<size, big_endian>*,
  				   const unsigned char* prelocs,
  				   size_t reloc_count,
  				   Output_section*,
  				   Address output_offset,
  				   Output_file*);
  
    // A type shared by split_stack_adjust_reltype and find_functions.
    typedef std::map<section_offset_type, section_size_type> Function_offsets;
  
    // Check for -fsplit-stack routines calling non-split-stack routines.
    void
    split_stack_adjust(const Symbol_table*, const unsigned char* pshdrs,
  		     unsigned int sh_type, unsigned int shndx,
  		     const unsigned char* prelocs, size_t reloc_count,
  		     unsigned char* view, section_size_type view_size,
  		     Reloc_symbol_changes** reloc_map,
  		     const Sized_target<size, big_endian>* target);
  
    template<int sh_type>
    void
    split_stack_adjust_reltype(const Symbol_table*, const unsigned char* pshdrs,
  			     unsigned int shndx, const unsigned char* prelocs,
  			     size_t reloc_count, unsigned char* view,
  			     section_size_type view_size,
  			     Reloc_symbol_changes** reloc_map,
  			     const Sized_target<size, big_endian>* target);
  
    // Find all functions in a section.
    void
    find_functions(const unsigned char* pshdrs, unsigned int shndx,
  		 Function_offsets*);
  
    // Write out the local symbols.
    void
    write_local_symbols(Output_file*,
  		      const Stringpool_template<char>*,
  		      const Stringpool_template<char>*,
  		      Output_symtab_xindex*,
  		      Output_symtab_xindex*,
  		      off_t);
  
    // Record a mapping from discarded section SHNDX to the corresponding
    // kept section.
    void
    set_kept_comdat_section(unsigned int shndx, bool is_comdat,
  			  unsigned int symndx, uint64_t sh_size,
  			  Kept_section* kept_section)
    {
      Kept_comdat_section kept(sh_size, kept_section, symndx, is_comdat);
      this->kept_comdat_sections_.insert(std::make_pair(shndx, kept));
    }
  
    // Find the kept section corresponding to the discarded section
    // SHNDX.  Return true if found.
    bool
    get_kept_comdat_section(unsigned int shndx, bool* is_comdat,
  			  unsigned int *symndx, uint64_t* sh_size,
  			  Kept_section** kept_section) const
    {
      typename Kept_comdat_section_table::const_iterator p =
        this->kept_comdat_sections_.find(shndx);
      if (p == this->kept_comdat_sections_.end())
        return false;
      *is_comdat = p->second.is_comdat;
      *symndx = p->second.symndx;
      *sh_size = p->second.sh_size;
      *kept_section = p->second.kept_section;
      return true;
    }
  
    // Compute final local symbol value.  R_SYM is the local symbol index.
    // LV_IN points to a local symbol value containing the input value.
    // LV_OUT points to a local symbol value storing the final output value,
    // which must not be a merged symbol value since before calling this
    // method to avoid memory leak.  RELOCATABLE indicates whether we are
    // linking a relocatable output.  OUT_SECTIONS is an array of output
    // sections.  OUT_OFFSETS is an array of offsets of the sections.  SYMTAB
    // points to a symbol table.
    //
    // The method returns a status code at return.  If the return status is
    // CFLV_OK, *LV_OUT contains the final value.  If the return status is
    // CFLV_ERROR, *LV_OUT is 0.  If the return status is CFLV_DISCARDED,
    // *LV_OUT is not modified.
    inline Compute_final_local_value_status
    compute_final_local_value_internal(unsigned int r_sym,
  				     const Symbol_value<size>* lv_in,
  				     Symbol_value<size>* lv_out,
  				     bool relocatable,
  				     const Output_sections& out_sections,
  				     const std::vector<Address>& out_offsets,
  				     const Symbol_table* symtab);
  
    // The PLT offsets of local symbols.
    typedef Unordered_map<unsigned int, unsigned int> Local_plt_offsets;
  
    // Saved information for sections whose layout was deferred.
    struct Deferred_layout
    {
      static const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
      Deferred_layout(unsigned int shndx, const char* name,
                      unsigned int sh_type,
                      const unsigned char* pshdr,
                      unsigned int reloc_shndx, unsigned int reloc_type)
        : name_(name), shndx_(shndx), reloc_shndx_(reloc_shndx),
          reloc_type_(reloc_type)
      {
        typename This::Shdr_write shdr(this->shdr_data_);
        memcpy(this->shdr_data_, pshdr, shdr_size);
        shdr.put_sh_type(sh_type);
      }
      std::string name_;
      unsigned int shndx_;
      unsigned int reloc_shndx_;
      unsigned int reloc_type_;
      unsigned char shdr_data_[shdr_size];
    };
  
    // General access to the ELF file.
    elfcpp::Elf_file<size, big_endian, Object> elf_file_;
    // Type of ELF file (ET_REL or ET_EXEC).  ET_EXEC files are allowed
    // as input files only for the --just-symbols option.
    int e_type_;
    // Index of SHT_SYMTAB section.
    unsigned int symtab_shndx_;
    // The number of local symbols.
    unsigned int local_symbol_count_;
    // The number of local symbols which go into the output file.
    unsigned int output_local_symbol_count_;
    // The number of local symbols which go into the output file's dynamic
    // symbol table.
    unsigned int output_local_dynsym_count_;
    // The entries in the symbol table for the external symbols.
    Symbols symbols_;
    // Number of symbols defined in object file itself.
    size_t defined_count_;
    // File offset for local symbols (relative to start of symbol table).
    off_t local_symbol_offset_;
    // File offset for local dynamic symbols (absolute).
    off_t local_dynsym_offset_;
    // Values of local symbols.
    Local_values local_values_;
    // PLT offsets for local symbols.
    Local_plt_offsets local_plt_offsets_;
    // Table mapping discarded comdat sections to corresponding kept sections.
    Kept_comdat_section_table kept_comdat_sections_;
    // Whether this object has a GNU style .eh_frame section.
    bool has_eh_frame_;
    // True if the layout of this object was deferred, waiting for plugin
    // replacement files.
    bool is_deferred_layout_;
    // The list of sections whose layout was deferred.
    std::vector<Deferred_layout> deferred_layout_;
    // The list of relocation sections whose layout was deferred.
    std::vector<Deferred_layout> deferred_layout_relocs_;
    // Pointer to the list of output views; valid only during do_relocate().
    const Views* output_views_;
  };
  
  // A class to manage the list of all objects.
  
  class Input_objects
  {
   public:
    Input_objects()
      : relobj_list_(), dynobj_list_(), sonames_(), cref_(NULL)
    { }
  
    // The type of the list of input relocateable objects.
    typedef std::vector<Relobj*> Relobj_list;
    typedef Relobj_list::const_iterator Relobj_iterator;
  
    // The type of the list of input dynamic objects.
    typedef std::vector<Dynobj*> Dynobj_list;
    typedef Dynobj_list::const_iterator Dynobj_iterator;
  
    // Add an object to the list.  Return true if all is well, or false
    // if this object should be ignored.
    bool
    add_object(Object*);
  
    // Start processing an archive.
    void
    archive_start(Archive*);
  
    // Stop processing an archive.
    void
    archive_stop(Archive*);
  
    // For each dynamic object, check whether we've seen all of its
    // explicit dependencies.
    void
    check_dynamic_dependencies() const;
  
    // Return whether an object was found in the system library
    // directory.
    bool
    found_in_system_library_directory(const Object*) const;
  
    // Print symbol counts.
    void
    print_symbol_counts(const Symbol_table*) const;
  
    // Print a cross reference table.
    void
    print_cref(const Symbol_table*, FILE*) const;
  
    // Iterate over all regular objects.
  
    Relobj_iterator
    relobj_begin() const
    { return this->relobj_list_.begin(); }
  
    Relobj_iterator
    relobj_end() const
    { return this->relobj_list_.end(); }
  
    // Iterate over all dynamic objects.
  
    Dynobj_iterator
    dynobj_begin() const
    { return this->dynobj_list_.begin(); }
  
    Dynobj_iterator
    dynobj_end() const
    { return this->dynobj_list_.end(); }
  
    // Return whether we have seen any dynamic objects.
    bool
    any_dynamic() const
    { return !this->dynobj_list_.empty(); }
  
    // Return the number of non dynamic objects.
    int
    number_of_relobjs() const
    { return this->relobj_list_.size(); }
  
    // Return the number of input objects.
    int
    number_of_input_objects() const
    { return this->relobj_list_.size() + this->dynobj_list_.size(); }
  
   private:
    Input_objects(const Input_objects&);
    Input_objects& operator=(const Input_objects&);
  
    // The list of ordinary objects included in the link.
    Relobj_list relobj_list_;
    // The list of dynamic objects included in the link.
    Dynobj_list dynobj_list_;
    // SONAMEs that we have seen.
    Unordered_map<std::string, Object*> sonames_;
    // Manage cross-references if requested.
    Cref* cref_;
  };
  
  // Some of the information we pass to the relocation routines.  We
  // group this together to avoid passing a dozen different arguments.
  
  template<int size, bool big_endian>
  struct Relocate_info
  {
    // Symbol table.
    const Symbol_table* symtab;
    // Layout.
    const Layout* layout;
    // Object being relocated.
    Sized_relobj_file<size, big_endian>* object;
    // Section index of relocation section.
    unsigned int reloc_shndx;
    // Section header of relocation section.
    const unsigned char* reloc_shdr;
    // Info about how relocs should be handled
    Relocatable_relocs* rr;
    // Section index of section being relocated.
    unsigned int data_shndx;
    // Section header of data section.
    const unsigned char* data_shdr;
  
    // Return a string showing the location of a relocation.  This is
    // only used for error messages.
    std::string
    location(size_t relnum, off_t reloffset) const;
  };
  
  // This is used to represent a section in an object and is used as the
  // key type for various section maps.
  typedef std::pair<Relobj*, unsigned int> Section_id;
  
  // This is similar to Section_id but is used when the section
  // pointers are const.
  typedef std::pair<const Relobj*, unsigned int> Const_section_id;
  
  // The hash value is based on the address of an object in memory during
  // linking.  It is okay to use this for looking up sections but never use
  // this in an unordered container that we want to traverse in a repeatable
  // manner.
  
  struct Section_id_hash
  {
    size_t operator()(const Section_id& loc) const
    { return reinterpret_cast<uintptr_t>(loc.first) ^ loc.second; }
  };
  
  struct Const_section_id_hash
  {
    size_t operator()(const Const_section_id& loc) const
    { return reinterpret_cast<uintptr_t>(loc.first) ^ loc.second; }
  };
  
  // Return whether INPUT_FILE contains an ELF object start at file
  // offset OFFSET.  This sets *START to point to a view of the start of
  // the file.  It sets *READ_SIZE to the number of bytes in the view.
  
  extern bool
  is_elf_object(Input_file* input_file, off_t offset,
  	      const unsigned char** start, int* read_size);
  
  // Return an Object appropriate for the input file.  P is BYTES long,
  // and holds the ELF header.  If PUNCONFIGURED is not NULL, then if
  // this sees an object the linker is not configured to support, it
  // sets *PUNCONFIGURED to true and returns NULL without giving an
  // error message.
  
  extern Object*
  make_elf_object(const std::string& name, Input_file*,
  		off_t offset, const unsigned char* p,
  		section_offset_type bytes, bool* punconfigured);
  
  } // end namespace gold
  
  #endif // !defined(GOLD_OBJECT_H)
  