gold/target-select.cc

   1 // target-select.cc -- select a target for an object file
   2
   3 // Copyright 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
   4 // Written by Ian Lance Taylor <iant@google.com>.
   5
   6 // This file is part of gold.
   7
   8 // This program is free software; you can redistribute it and/or modify
   9 // it under the terms of the GNU General Public License as published by
  10 // the Free Software Foundation; either version 3 of the License, or
  11 // (at your option) any later version.
  12
  13 // This program is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17
  18 // You should have received a copy of the GNU General Public License
  19 // along with this program; if not, write to the Free Software
  20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  21 // MA 02110-1301, USA.
  22
  23 #include "gold.h"
  24
  25 #include <cstdio>
  26 #include <cstring>
  27
  28 #include "elfcpp.h"
  29 #include "options.h"
  30 #include "parameters.h"
  31 #include "target-select.h"
  32
  33 namespace
  34 {
  35
  36 // The start of the list of target selectors.
  37
  38 gold::Target_selector* target_selectors;
  39
  40 } // End anonymous namespace.
  41
  42 namespace gold
  43 {
  44
  45 // Class Set_target_once.
  46
  47 void
  48 Set_target_once::do_run_once(void*)
  49 {
  50   this->target_selector_->set_target();
  51 }
  52
  53 // Construct a Target_selector, which means adding it to the linked
  54 // list.  This runs at global constructor time, so we want it to be
  55 // fast.
  56
  57 Target_selector::Target_selector(int machine, int size, bool is_big_endian,
  58                                  const char* bfd_name, const char* emulation)
  59   : machine_(machine), size_(size), is_big_endian_(is_big_endian),
  60     bfd_name_(bfd_name), emulation_(emulation), instantiated_target_(NULL),
  61     set_target_once_(this)
  62 {
  63   this->next_ = target_selectors;
  64   target_selectors = this;
  65 }
  66
  67 // Instantiate the target and return it.  Use SET_TARGET_ONCE_ to
  68 // avoid instantiating two instances of the same target.
  69
  70 Target*
  71 Target_selector::instantiate_target()
  72 {
  73   this->set_target_once_.run_once(NULL);
  74   return this->instantiated_target_;
  75 }
  76
  77 // Instantiate the target.  This is called at most once.
  78
  79 void
  80 Target_selector::set_target()
  81 {
  82   gold_assert(this->instantiated_target_ == NULL);
  83   this->instantiated_target_ = this->do_instantiate_target();
  84 }
  85
  86 // If we instantiated TARGET, return the corresponding BFD name.
  87
  88 const char*
  89 Target_selector::do_target_bfd_name(const Target* target)
  90 {
  91   if (!this->is_our_target(target))
  92     return NULL;
  93   const char* my_bfd_name = this->bfd_name();
  94   gold_assert(my_bfd_name != NULL);
  95   return my_bfd_name;
  96 }
  97
  98 // Find the target for an ELF file.
  99
 100 Target*
 101 select_target(int machine, int size, bool is_big_endian, int osabi,
 102               int abiversion)
 103 {
 104   for (Target_selector* p = target_selectors; p != NULL; p = p->next())
 105     {
 106       int pmach = p->machine();
 107       if ((pmach == machine || pmach == elfcpp::EM_NONE)
 108           && p->get_size() == size
 109           && (p->is_big_endian() ? is_big_endian : !is_big_endian))
 110         {
 111           Target* ret = p->recognize(machine, osabi, abiversion);
 112           if (ret != NULL)
 113             return ret;
 114         }
 115     }
 116   return NULL;
 117 }
 118
 119 // Find a target using a BFD name.  This is used to support the
 120 // --oformat option.
 121
 122 Target*
 123 select_target_by_bfd_name(const char* name)
 124 {
 125   for (Target_selector* p = target_selectors; p != NULL; p = p->next())
 126     {
 127       const char* pname = p->bfd_name();
 128       if (pname == NULL || strcmp(pname, name) == 0)
 129         {
 130           Target* ret = p->recognize_by_bfd_name(name);
 131           if (ret != NULL)
 132             return ret;
 133         }
 134     }
 135   return NULL;
 136 }
 137
 138 // Find a target using a GNU linker emulation.  This is used to
 139 // support the -m option.
 140
 141 Target*
 142 select_target_by_emulation(const char* name)
 143 {
 144   for (Target_selector* p = target_selectors; p != NULL; p = p->next())
 145     {
 146       const char* pname = p->emulation();
 147       if (pname == NULL || strcmp(pname, name) == 0)
 148         {
 149           Target* ret = p->recognize_by_emulation(name);
 150           if (ret != NULL)
 151             return ret;
 152         }
 153     }
 154   return NULL;
 155 }
 156
 157 // Push all the supported BFD names onto a vector.
 158
 159 void
 160 supported_target_names(std::vector<const char*>* names)
 161 {
 162   for (Target_selector* p = target_selectors; p != NULL; p = p->next())
 163     p->supported_bfd_names(names);
 164 }
 165
 166 // Push all the supported emulations onto a vector.
 167
 168 void
 169 supported_emulation_names(std::vector<const char*>* names)
 170 {
 171   for (Target_selector* p = target_selectors; p != NULL; p = p->next())
 172     p->supported_emulations(names);
 173 }
 174
 175 // Implement the --print-output-format option.
 176
 177 void
 178 print_output_format()
 179 {
 180   if (!parameters->target_valid())
 181     {
 182       // This case arises when --print-output-format is used with no
 183       // input files.  We need to come up with the right string to
 184       // print based on the other options.  If the user specified the
 185       // format using a --oformat option, use that.  That saves each
 186       // target from having to remember the name that was used to
 187       // select it.  In other cases, we will just have to ask the
 188       // target.
 189       if (parameters->options().user_set_oformat())
 190         {
 191           const char* bfd_name = parameters->options().oformat();
 192           Target* target = select_target_by_bfd_name(bfd_name);
 193           if (target != NULL)
 194             printf("%s\n", bfd_name);
 195           else
 196             gold_error(_("unrecognized output format %s"), bfd_name);
 197           return;
 198         }
 199
 200       parameters_force_valid_target();
 201     }
 202
 203   const Target* target = &parameters->target();
 204   for (Target_selector* p = target_selectors; p != NULL; p = p->next())
 205     {
 206       const char* bfd_name = p->target_bfd_name(target);
 207       if (bfd_name != NULL)
 208         {
 209           printf("%s\n", bfd_name);
 210           return;
 211         }
 212     }
 213
 214   gold_unreachable();
 215 }
 216
 217 } // End namespace gold.