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// icf.h --  Identical Code Folding

// Copyright 2009 Free Software Foundation, Inc.

// Written by Sriraman Tallam <tmsriram@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_ICF_H

#define GOLD_ICF_H

#include <vector>

#include "elfcpp.h"

#include "symtab.h"

namespace gold

{

class Object;

class Input_objects;

class Symbol_table;

typedef std::pair<Object*, unsigned int> Section_id;

class Icf

{

 public:

  struct Section_id_hash

  {

    size_t operator()(const Section_id& loc) const

    { return reinterpret_cast<uintptr_t>(loc.first) ^ loc.second; }

  };

  typedef std::vector<Section_id> Sections_reachable_list;

  typedef std::vector<Symbol*> Symbol_info;

  typedef std::vector<std::pair<long long, long long> > Addend_info;

  typedef Unordered_map<Section_id,

                        Sections_reachable_list,

                        Section_id_hash> Section_list;

  typedef Unordered_map<Section_id, Symbol_info, Section_id_hash> Symbol_list;

  typedef Unordered_map<Section_id, Addend_info, Section_id_hash> Addend_list;

  typedef Unordered_map<Section_id,

                        unsigned int,

                        Section_id_hash> Uniq_secn_id_map;

  Icf()

  : id_section_(), section_id_(), kept_section_id_(),

    num_tracked_relocs(NULL), icf_ready_(false),

    section_reloc_list_(), symbol_reloc_list_(),

    addend_reloc_list_()

  { }

  // Returns the kept folded identical section corresponding to

  // dup_obj and dup_shndx.

  Section_id

  get_folded_section(Object* dup_obj, unsigned int dup_shndx);

  // Forms groups of identical sections where the first member

  // of each group is the kept section during folding.

  void

  find_identical_sections(const Input_objects* input_objects,

                          Symbol_table* symtab);

  // This is set when ICF has been run and the groups of

  // identical sections have been formed.

  void

  icf_ready()

  { this->icf_ready_ = true; }

  // Returns true if ICF has been run.

  bool

  is_icf_ready()

  { return this->icf_ready_; }

  // Unfolds the section denoted by OBJ and SHNDX if folded.

  void

  unfold_section(Object* obj, unsigned int shndx);

  // Returns the kept section corresponding to the 

  // given section.

  bool

  is_section_folded(Object* obj, unsigned int shndx);

  // Returns a map of a section to a list of all sections referenced

  // by its relocations.

  Section_list&

  section_reloc_list()

  { return this->section_reloc_list_; }

  // Returns a map of  a section to a list of all symbols referenced

  // by its relocations.

  Symbol_list&

  symbol_reloc_list()

  { return this->symbol_reloc_list_; }

  // Returns a maps of a section to a list of symbol values and addends

  // of its relocations.

  Addend_list&

  addend_reloc_list()

  { return this->addend_reloc_list_; }

  // Returns a mapping of each section to a unique integer.

  Uniq_secn_id_map&

  section_to_int_map()

  { return this->section_id_; }

 private:

  // Maps integers to sections.

  std::vector<Section_id> id_section_;

  // Does the reverse.

  Uniq_secn_id_map section_id_;

  // Given a section id, this maps it to the id of the kept

  // section.  If the id's are the same then this section is

  // not folded.

  std::vector<unsigned int> kept_section_id_;

  unsigned int* num_tracked_relocs;

  // Flag to indicate if ICF has been run.

  bool icf_ready_;

  // These lists are populated by gc_process_relocs in gc.h.

  Section_list section_reloc_list_;

  Symbol_list symbol_reloc_list_;

  Addend_list addend_reloc_list_;

};

} // End of namespace gold.

#endif