gold/target-select.cc

   1 // target-select.cc -- select a target for an object file
   2
   3 // Copyright (C) 2006-2017 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(Input_file* input_file, off_t offset,
 102               int machine, int size, bool is_big_endian,
 103               int osabi, int abiversion)
 104 {
 105   for (Target_selector* p = target_selectors; p != NULL; p = p->next())
 106     {
 107       int pmach = p->machine();
 108       if ((pmach == machine || pmach == elfcpp::EM_NONE)
 109           && p->get_size() == size
 110           && (p->is_big_endian() ? is_big_endian : !is_big_endian))
 111         {
 112           Target* ret = p->recognize(input_file, offset,
 113                                      machine, osabi, abiversion);
 114           if (ret != NULL)
 115             return ret;
 116         }
 117     }
 118   return NULL;
 119 }
 120
 121 // Find a target using a BFD name.  This is used to support the
 122 // --oformat option.
 123
 124 Target*
 125 select_target_by_bfd_name(const char* name)
 126 {
 127   for (Target_selector* p = target_selectors; p != NULL; p = p->next())
 128     {
 129       const char* pname = p->bfd_name();
 130       if (pname == NULL || strcmp(pname, name) == 0)
 131         {
 132           Target* ret = p->recognize_by_bfd_name(name);
 133           if (ret != NULL)
 134             return ret;
 135         }
 136     }
 137   return NULL;
 138 }
 139
 140 // Find a target using a GNU linker emulation.  This is used to
 141 // support the -m option.
 142
 143 Target*
 144 select_target_by_emulation(const char* name)
 145 {
 146   for (Target_selector* p = target_selectors; p != NULL; p = p->next())
 147     {
 148       const char* pname = p->emulation();
 149       if (pname == NULL || strcmp(pname, name) == 0)
 150         {
 151           Target* ret = p->recognize_by_emulation(name);
 152           if (ret != NULL)
 153             return ret;
 154         }
 155     }
 156   return NULL;
 157 }
 158
 159 // Push all the supported BFD names onto a vector.
 160
 161 void
 162 supported_target_names(std::vector<const char*>* names)
 163 {
 164   for (Target_selector* p = target_selectors; p != NULL; p = p->next())
 165     p->supported_bfd_names(names);
 166 }
 167
 168 // Push all the supported emulations onto a vector.
 169
 170 void
 171 supported_emulation_names(std::vector<const char*>* names)
 172 {
 173   for (Target_selector* p = target_selectors; p != NULL; p = p->next())
 174     p->supported_emulations(names);
 175 }
 176
 177 // Implement the --print-output-format option.
 178
 179 void
 180 print_output_format()
 181 {
 182   if (!parameters->target_valid())
 183     {
 184       // This case arises when --print-output-format is used with no
 185       // input files.  We need to come up with the right string to
 186       // print based on the other options.  If the user specified the
 187       // format using a --oformat option, use that.  That saves each
 188       // target from having to remember the name that was used to
 189       // select it.  In other cases, we will just have to ask the
 190       // target.
 191       if (parameters->options().user_set_oformat())
 192         {
 193           const char* bfd_name = parameters->options().oformat();
 194           Target* target = select_target_by_bfd_name(bfd_name);
 195           if (target != NULL)
 196             printf("%s\n", bfd_name);
 197           else
 198             gold_error(_("unrecognized output format %s"), bfd_name);
 199           return;
 200         }
 201
 202       parameters_force_valid_target();
 203     }
 204
 205   const Target* target = &parameters->target();
 206   for (Target_selector* p = target_selectors; p != NULL; p = p->next())
 207     {
 208       const char* bfd_name = p->target_bfd_name(target);
 209       if (bfd_name != NULL)
 210         {
 211           printf("%s\n", bfd_name);
 212           return;
 213         }
 214     }
 215
 216   gold_unreachable();
 217 }
 218
 219 } // End namespace gold.