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// target.cc -- target support for gold.

// Copyright 2009, 2010, 2011 Free Software Foundation, Inc.

// Written by Doug Kwan <dougkwan@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 "elfcpp.h"

#include "dynobj.h"

#include "symtab.h"

#include "output.h"

#include "target.h"

namespace gold

{

// Return whether NAME is a local label name.  This is used to implement the

// --discard-locals options and can be overridden by child classes to

// implement system-specific behaviour.  The logic here is the same as that

// in _bfd_elf_is_local_label_name().

bool

Target::do_is_local_label_name(const char* name) const

{

  // Normal local symbols start with ``.L''.

  if (name[0] == '.' && name[1] == 'L')

    return true;

  // At least some SVR4 compilers (e.g., UnixWare 2.1 cc) generate

  // DWARF debugging symbols starting with ``..''.

  if (name[0] == '.' && name[1] == '.')

    return true;

  // gcc will sometimes generate symbols beginning with ``_.L_'' when

  // emitting DWARF debugging output.  I suspect this is actually a

  // small bug in gcc (it calls ASM_OUTPUT_LABEL when it should call

  // ASM_GENERATE_INTERNAL_LABEL, and this causes the leading

  // underscore to be emitted on some ELF targets).  For ease of use,

  // we treat such symbols as local.

  if (name[0] == '_' && name[1] == '.' && name[2] == 'L' && name[3] == '_')

    return true;

  return false;

}

// Implementations of methods Target::do_make_elf_object are almost identical

// except for the address sizes and endianities.  So we extract this

// into a template.

template<int size, bool big_endian>

inline Object*

Target::do_make_elf_object_implementation(

    const std::string& name,

    Input_file* input_file,

    off_t offset,

    const elfcpp::Ehdr<size, big_endian>& ehdr)

{

  int et = ehdr.get_e_type();

  // ET_EXEC files are valid input for --just-symbols/-R,

  // and we treat them as relocatable objects.

  if (et == elfcpp::ET_REL

      || (et == elfcpp::ET_EXEC && input_file->just_symbols()))

    {

      Sized_relobj_file<size, big_endian>* obj =

        new Sized_relobj_file<size, big_endian>(name, input_file, offset, ehdr);

      obj->setup();

      return obj;

    }

  else if (et == elfcpp::ET_DYN)

    {

      Sized_dynobj<size, big_endian>* obj =

        new Sized_dynobj<size, big_endian>(name, input_file, offset, ehdr);

      obj->setup();

      return obj;

    }

  else

    {

      gold_error(_("%s: unsupported ELF file type %d"),

                 name.c_str(), et);

      return NULL;

    }

}

// Make an ELF object called NAME by reading INPUT_FILE at OFFSET.  EHDR

// is the ELF header of the object.  There are four versions of this

// for different address sizes and endianities.

#ifdef HAVE_TARGET_32_LITTLE

Object*

Target::do_make_elf_object(const std::string& name, Input_file* input_file,

                           off_t offset, const elfcpp::Ehdr<32, false>& ehdr)

{

  return this->do_make_elf_object_implementation<32, false>(name, input_file,

                                                            offset, ehdr);

}

#endif

#ifdef HAVE_TARGET_32_BIG

Object*

Target::do_make_elf_object(const std::string& name, Input_file* input_file,

                           off_t offset, const elfcpp::Ehdr<32, true>& ehdr)

{

  return this->do_make_elf_object_implementation<32, true>(name, input_file,

                                                           offset, ehdr);

}

#endif

#ifdef HAVE_TARGET_64_LITTLE

Object*

Target::do_make_elf_object(const std::string& name, Input_file* input_file,

                           off_t offset, const elfcpp::Ehdr<64, false>& ehdr)

{

  return this->do_make_elf_object_implementation<64, false>(name, input_file,

                                                            offset, ehdr);

}

#endif

#ifdef HAVE_TARGET_64_BIG

Object*

Target::do_make_elf_object(const std::string& name, Input_file* input_file,

                           off_t offset, const elfcpp::Ehdr<64, true>& ehdr)

{

  return this->do_make_elf_object_implementation<64, true>(name, input_file,

                                                           offset, ehdr);

}

#endif

Output_section*

Target::do_make_output_section(const char* name, elfcpp::Elf_Word type,

                               elfcpp::Elf_Xword flags)

{

  return new Output_section(name, type, flags);

}

// Default for whether a reloc is a call to a non-split function is

// whether the symbol is a function.

bool

Target::do_is_call_to_non_split(const Symbol* sym, unsigned int) const

{

  return sym->type() == elfcpp::STT_FUNC;

}

// Default conversion for -fsplit-stack is to give an error.

void

Target::do_calls_non_split(Relobj* object, unsigned int, section_offset_type,

                           section_size_type, unsigned char*, section_size_type,

                           std::string*, std::string*) const

{

  static bool warned;

  if (!warned)

    {

      gold_error(_("linker does not include stack split support "

                   "required by %s"),

                 object->name().c_str());

      warned = true;

    }

}

//  Return whether BYTES/LEN matches VIEW/VIEW_SIZE at OFFSET.

bool

Target::match_view(const unsigned char* view, section_size_type view_size,

                   section_offset_type offset, const char* bytes,

                   size_t len) const

{

  if (offset + len > view_size)

    return false;

  return memcmp(view + offset, bytes, len) == 0;

}

// Set the contents of a VIEW/VIEW_SIZE to nops starting at OFFSET

// for LEN bytes.

void

Target::set_view_to_nop(unsigned char* view, section_size_type view_size,

                        section_offset_type offset, size_t len) const

{

  gold_assert(offset >= 0 && offset + len <= view_size);

  if (!this->has_code_fill())

    memset(view + offset, 0, len);

  else

    {

      std::string fill = this->code_fill(len);

      memcpy(view + offset, fill.data(), len);

    }

}

// Class Sized_target.

// Set the EI_OSABI field of the ELF header if requested.

template<int size, bool big_endian>

void

Sized_target<size, big_endian>::do_adjust_elf_header(unsigned char* view,

                                                     int len) const

{

  elfcpp::ELFOSABI osabi = this->osabi();

  if (osabi != elfcpp::ELFOSABI_NONE)

    {

      gold_assert(len == elfcpp::Elf_sizes<size>::ehdr_size);

      elfcpp::Ehdr<size, false> ehdr(view);

      unsigned char e_ident[elfcpp::EI_NIDENT];

      memcpy(e_ident, ehdr.get_e_ident(), elfcpp::EI_NIDENT);

      e_ident[elfcpp::EI_OSABI] = osabi;

      elfcpp::Ehdr_write<size, false> oehdr(view);

      oehdr.put_e_ident(e_ident);

    }

}

#ifdef HAVE_TARGET_32_LITTLE

template

class Sized_target<32, false>;

#endif

#ifdef HAVE_TARGET_32_BIG

template

class Sized_target<32, true>;

#endif

#ifdef HAVE_TARGET_64_LITTLE

template

class Sized_target<64, false>;

#endif

#ifdef HAVE_TARGET_64_BIG

template

class Sized_target<64, true>;

#endif

} // End namespace gold.