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// target-select.cc -- select a target for an object file

// Copyright 2006, 2007, 2008, 2009, 2010, 2011 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.

#include "gold.h"

#include <cstdio>

#include <cstring>

#include "elfcpp.h"

#include "options.h"

#include "parameters.h"

#include "target-select.h"

namespace

{

// The start of the list of target selectors.

gold::Target_selector* target_selectors;

} // End anonymous namespace.

namespace gold

{

// Class Set_target_once.

void

Set_target_once::do_run_once(void*)

{

  this->target_selector_->set_target();

}

// Construct a Target_selector, which means adding it to the linked

// list.  This runs at global constructor time, so we want it to be

// fast.

Target_selector::Target_selector(int machine, int size, bool is_big_endian,

                                 const char* bfd_name, const char* emulation)

  : machine_(machine), size_(size), is_big_endian_(is_big_endian),

    bfd_name_(bfd_name), emulation_(emulation), instantiated_target_(NULL),

    set_target_once_(this)

{

  this->next_ = target_selectors;

  target_selectors = this;

}

// Instantiate the target and return it.  Use SET_TARGET_ONCE_ to

// avoid instantiating two instances of the same target.

Target*

Target_selector::instantiate_target()

{

  this->set_target_once_.run_once(NULL);

  return this->instantiated_target_;

}

// Instantiate the target.  This is called at most once.

void

Target_selector::set_target()

{

  gold_assert(this->instantiated_target_ == NULL);

  this->instantiated_target_ = this->do_instantiate_target();

}

// If we instantiated TARGET, return the corresponding BFD name.

const char*

Target_selector::do_target_bfd_name(const Target* target)

{

  if (!this->is_our_target(target))

    return NULL;

  const char* my_bfd_name = this->bfd_name();

  gold_assert(my_bfd_name != NULL);

  return my_bfd_name;

}

// Find the target for an ELF file.

Target*

select_target(int machine, int size, bool is_big_endian, int osabi,

              int abiversion)

{

  for (Target_selector* p = target_selectors; p != NULL; p = p->next())

    {

      int pmach = p->machine();

      if ((pmach == machine || pmach == elfcpp::EM_NONE)

          && p->get_size() == size

          && (p->is_big_endian() ? is_big_endian : !is_big_endian))

        {

          Target* ret = p->recognize(machine, osabi, abiversion);

          if (ret != NULL)

            return ret;

        }

    }

  return NULL;

}

// Find a target using a BFD name.  This is used to support the

// --oformat option.

Target*

select_target_by_bfd_name(const char* name)

{

  for (Target_selector* p = target_selectors; p != NULL; p = p->next())

    {

      const char* pname = p->bfd_name();

      if (pname == NULL || strcmp(pname, name) == 0)

        {

          Target* ret = p->recognize_by_bfd_name(name);

          if (ret != NULL)

            return ret;

        }

    }

  return NULL;

}

// Find a target using a GNU linker emulation.  This is used to

// support the -m option.

Target*

select_target_by_emulation(const char* name)

{

  for (Target_selector* p = target_selectors; p != NULL; p = p->next())

    {

      const char* pname = p->emulation();

      if (pname == NULL || strcmp(pname, name) == 0)

        {

          Target* ret = p->recognize_by_emulation(name);

          if (ret != NULL)

            return ret;

        }

    }

  return NULL;

}

// Push all the supported BFD names onto a vector.

void

supported_target_names(std::vector<const char*>* names)

{

  for (Target_selector* p = target_selectors; p != NULL; p = p->next())

    p->supported_bfd_names(names);

}

// Push all the supported emulations onto a vector.

void

supported_emulation_names(std::vector<const char*>* names)

{

  for (Target_selector* p = target_selectors; p != NULL; p = p->next())

    p->supported_emulations(names);

}

// Implement the --print-output-format option.

void

print_output_format()

{

  if (!parameters->target_valid())

    {

      // This case arises when --print-output-format is used with no

      // input files.  We need to come up with the right string to

      // print based on the other options.  If the user specified the

      // format using a --oformat option, use that.  That saves each

      // target from having to remember the name that was used to

      // select it.  In other cases, we will just have to ask the

      // target.

      if (parameters->options().user_set_oformat())

        {

          const char* bfd_name = parameters->options().oformat();

          Target* target = select_target_by_bfd_name(bfd_name);

          if (target != NULL)

            printf("%s\n", bfd_name);

          else

            gold_error(_("unrecognized output format %s"), bfd_name);

          return;

        }

      parameters_force_valid_target();

    }

  const Target* target = &parameters->target();

  for (Target_selector* p = target_selectors; p != NULL; p = p->next())

    {

      const char* bfd_name = p->target_bfd_name(target);

      if (bfd_name != NULL)

        {

          printf("%s\n", bfd_name);

          return;

        }

    }

  gold_unreachable();

}

} // End namespace gold.