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// gc.cc -- garbage collection of unused sections

// 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.

#include "gold.h"

#include "object.h"

#include "gc.h"

#include "symtab.h"

namespace gold

{

// Garbage collection uses a worklist style algorithm to determine the 

// transitive closure of all referenced sections.

void

Garbage_collection::do_transitive_closure()

{

  while (!this->worklist().empty())

    {

      // Add elements from the work list to the referenced list

      // one by one.

      Section_id entry = this->worklist().front();

      this->worklist().pop();

      if (this->referenced_list().find(entry)

          == this->referenced_list().end())

        {

          this->referenced_list().insert(entry);

        }

      else

        {

          continue;

        }

      Garbage_collection::Section_ref::iterator find_it =

                this->section_reloc_map().find(entry);

      if (find_it == this->section_reloc_map().end())

          continue;

      Garbage_collection::Sections_reachable v = find_it->second;

      // Scan the vector of references for each work_list entry. 

      for (Garbage_collection::Sections_reachable::iterator it_v = v.begin();

           it_v != v.end();

           ++it_v)

        {

          // Do not add already processed sections to the work_list. 

          if (this->referenced_list().find(*it_v)

              == this->referenced_list().end())

            {

              this->worklist().push(*it_v);

            }

        }

    }

  this->worklist_ready();

}

} // End namespace gold.