1 // gold.cc -- main linker functions
3 // Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
6 // This file is part of gold.
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.
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.
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.
30 #include "libiberty.h"
34 #include "workqueue.h"
35 #include "dirsearch.h"
48 const char* program_name;
51 gold_exit(bool status)
53 if (!status && parameters != NULL && parameters->options_valid())
54 unlink_if_ordinary(parameters->options().output_file_name());
55 exit(status ? EXIT_SUCCESS : EXIT_FAILURE);
61 // We are out of memory, so try hard to print a reasonable message.
62 // Note that we don't try to translate this message, since the
63 // translation process itself will require memory.
65 // LEN only exists to avoid a pointless warning when write is
66 // declared with warn_use_result, as when compiling with
67 // -D_USE_FORTIFY on GNU/Linux. Casting to void does not appear to
68 // work, at least not with gcc 4.3.0.
70 ssize_t len = write(2, program_name, strlen(program_name));
73 const char* const s = ": out of memory\n";
74 len = write(2, s, strlen(s));
79 // Handle an unreachable case.
82 do_gold_unreachable(const char* filename, int lineno, const char* function)
84 fprintf(stderr, _("%s: internal error in %s, at %s:%d\n"),
85 program_name, function, filename, lineno);
89 // This class arranges to run the functions done in the middle of the
90 // link. It is just a closure.
92 class Middle_runner : public Task_function_runner
95 Middle_runner(const General_options& options,
96 const Input_objects* input_objects,
98 Layout* layout, Mapfile* mapfile)
99 : options_(options), input_objects_(input_objects), symtab_(symtab),
100 layout_(layout), mapfile_(mapfile)
104 run(Workqueue*, const Task*);
107 const General_options& options_;
108 const Input_objects* input_objects_;
109 Symbol_table* symtab_;
115 Middle_runner::run(Workqueue* workqueue, const Task* task)
117 queue_middle_tasks(this->options_, task, this->input_objects_, this->symtab_,
118 this->layout_, workqueue, this->mapfile_);
121 // Queue up the initial set of tasks for this link job.
124 queue_initial_tasks(const General_options& options,
125 Dirsearch& search_path,
126 const Command_line& cmdline,
127 Workqueue* workqueue, Input_objects* input_objects,
128 Symbol_table* symtab, Layout* layout, Mapfile* mapfile)
130 if (cmdline.begin() == cmdline.end())
131 gold_fatal(_("no input files"));
133 int thread_count = options.thread_count_initial();
134 if (thread_count == 0)
135 thread_count = cmdline.number_of_input_files();
136 workqueue->set_thread_count(thread_count);
138 // Read the input files. We have to add the symbols to the symbol
139 // table in order. We do this by creating a separate blocker for
140 // each input file. We associate the blocker with the following
141 // input file, to give us a convenient place to delete it.
142 Task_token* this_blocker = NULL;
143 for (Command_line::const_iterator p = cmdline.begin();
147 Task_token* next_blocker = new Task_token(true);
148 next_blocker->add_blocker();
149 workqueue->queue(new Read_symbols(options, input_objects, symtab, layout,
150 &search_path, mapfile, &*p, NULL,
151 this_blocker, next_blocker));
152 this_blocker = next_blocker;
155 if (options.has_plugins())
157 Task_token* next_blocker = new Task_token(true);
158 next_blocker->add_blocker();
159 workqueue->queue(new Plugin_hook(options, input_objects, symtab, layout,
160 &search_path, mapfile, this_blocker,
162 this_blocker = next_blocker;
165 workqueue->queue(new Task_function(new Middle_runner(options,
171 "Task_function Middle_runner"));
174 // Queue up the middle set of tasks. These are the tasks which run
175 // after all the input objects have been found and all the symbols
176 // have been read, but before we lay out the output file.
179 queue_middle_tasks(const General_options& options,
181 const Input_objects* input_objects,
182 Symbol_table* symtab,
184 Workqueue* workqueue,
187 // We have to support the case of not seeing any input objects, and
188 // generate an empty file. Existing builds depend on being able to
189 // pass an empty archive to the linker and get an empty object file
190 // out. In order to do this we need to use a default target.
191 if (input_objects->number_of_input_objects() == 0)
192 set_parameters_target(¶meters->default_target());
194 int thread_count = options.thread_count_middle();
195 if (thread_count == 0)
196 thread_count = std::max(2, input_objects->number_of_input_objects());
197 workqueue->set_thread_count(thread_count);
199 // Now we have seen all the input files.
200 const bool doing_static_link = (!input_objects->any_dynamic()
201 && !parameters->options().shared());
202 set_parameters_doing_static_link(doing_static_link);
203 if (!doing_static_link && options.is_static())
205 // We print out just the first .so we see; there may be others.
206 gold_error(_("cannot mix -static with dynamic object %s"),
207 (*input_objects->dynobj_begin())->name().c_str());
209 if (!doing_static_link && parameters->options().relocatable())
210 gold_error(_("cannot mix -r with dynamic object %s"),
211 (*input_objects->dynobj_begin())->name().c_str());
212 if (!doing_static_link
213 && options.oformat_enum() != General_options::OBJECT_FORMAT_ELF)
214 gold_fatal(_("cannot use non-ELF output format with dynamic object %s"),
215 (*input_objects->dynobj_begin())->name().c_str());
217 if (is_debugging_enabled(DEBUG_SCRIPT))
218 layout->script_options()->print(stderr);
220 // For each dynamic object, record whether we've seen all the
221 // dynamic objects that it depends upon.
222 input_objects->check_dynamic_dependencies();
224 // See if any of the input definitions violate the One Definition Rule.
225 // TODO: if this is too slow, do this as a task, rather than inline.
226 symtab->detect_odr_violations(task, options.output_file_name());
228 // Create any output sections required by any linker script.
229 layout->create_script_sections();
231 // Define some sections and symbols needed for a dynamic link. This
232 // handles some cases we want to see before we read the relocs.
233 layout->create_initial_dynamic_sections(symtab);
235 // Define symbols from any linker scripts.
236 layout->define_script_symbols(symtab);
238 // Add any symbols named with -u options to the symbol table.
239 symtab->add_undefined_symbols_from_command_line();
241 // Attach sections to segments.
242 layout->attach_sections_to_segments();
244 if (!parameters->options().relocatable())
246 // Predefine standard symbols.
247 define_standard_symbols(symtab, layout);
249 // Define __start and __stop symbols for output sections where
251 layout->define_section_symbols(symtab);
254 // Make sure we have symbols for any required group signatures.
255 layout->define_group_signatures(symtab);
257 // Read the relocations of the input files. We do this to find
258 // which symbols are used by relocations which require a GOT and/or
259 // a PLT entry, or a COPY reloc. When we implement garbage
260 // collection we will do it here by reading the relocations in a
261 // breadth first search by references.
263 // We could also read the relocations during the first pass, and
264 // mark symbols at that time. That is how the old GNU linker works.
265 // Doing that is more complex, since we may later decide to discard
266 // some of the sections, and thus change our minds about the types
267 // of references made to the symbols.
268 Task_token* blocker = new Task_token(true);
269 Task_token* symtab_lock = new Task_token(false);
270 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
271 p != input_objects->relobj_end();
274 // We can read and process the relocations in any order. But we
275 // only want one task to write to the symbol table at a time.
276 // So we queue up a task for each object to read the
277 // relocations. That task will in turn queue a task to wait
278 // until it can write to the symbol table.
279 blocker->add_blocker();
280 workqueue->queue(new Read_relocs(options, symtab, layout, *p,
281 symtab_lock, blocker));
284 // Allocate common symbols. This requires write access to the
285 // symbol table, but is independent of the relocation processing.
286 if (parameters->options().define_common())
288 blocker->add_blocker();
289 workqueue->queue(new Allocate_commons_task(symtab, layout, mapfile,
290 symtab_lock, blocker));
293 // When all those tasks are complete, we can start laying out the
295 // TODO(csilvers): figure out a more principled way to get the target
296 Target* target = const_cast<Target*>(¶meters->target());
297 workqueue->queue(new Task_function(new Layout_task_runner(options,
304 "Task_function Layout_task_runner"));
307 // Queue up the final set of tasks. This is called at the end of
311 queue_final_tasks(const General_options& options,
312 const Input_objects* input_objects,
313 const Symbol_table* symtab,
315 Workqueue* workqueue,
318 int thread_count = options.thread_count_final();
319 if (thread_count == 0)
320 thread_count = std::max(2, input_objects->number_of_input_objects());
321 workqueue->set_thread_count(thread_count);
323 bool any_postprocessing_sections = layout->any_postprocessing_sections();
325 // Use a blocker to wait until all the input sections have been
327 Task_token* input_sections_blocker = NULL;
328 if (!any_postprocessing_sections)
329 input_sections_blocker = new Task_token(true);
331 // Use a blocker to block any objects which have to wait for the
332 // output sections to complete before they can apply relocations.
333 Task_token* output_sections_blocker = new Task_token(true);
335 // Use a blocker to block the final cleanup task.
336 Task_token* final_blocker = new Task_token(true);
338 // Queue a task to write out the symbol table.
339 final_blocker->add_blocker();
340 workqueue->queue(new Write_symbols_task(layout,
348 // Queue a task to write out the output sections.
349 output_sections_blocker->add_blocker();
350 final_blocker->add_blocker();
351 workqueue->queue(new Write_sections_task(layout, of, output_sections_blocker,
354 // Queue a task to write out everything else.
355 final_blocker->add_blocker();
356 workqueue->queue(new Write_data_task(layout, symtab, of, final_blocker));
358 // Queue a task for each input object to relocate the sections and
359 // write out the local symbols.
360 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
361 p != input_objects->relobj_end();
364 if (input_sections_blocker != NULL)
365 input_sections_blocker->add_blocker();
366 final_blocker->add_blocker();
367 workqueue->queue(new Relocate_task(options, symtab, layout, *p, of,
368 input_sections_blocker,
369 output_sections_blocker,
373 // Queue a task to write out the output sections which depend on
374 // input sections. If there are any sections which require
375 // postprocessing, then we need to do this last, since it may resize
377 if (!any_postprocessing_sections)
379 final_blocker->add_blocker();
380 Task* t = new Write_after_input_sections_task(layout, of,
381 input_sections_blocker,
387 Task_token *new_final_blocker = new Task_token(true);
388 new_final_blocker->add_blocker();
389 Task* t = new Write_after_input_sections_task(layout, of,
393 final_blocker = new_final_blocker;
396 // Queue a task to close the output file. This will be blocked by
398 workqueue->queue(new Task_function(new Close_task_runner(&options, layout,
401 "Task_function Close_task_runner"));
404 } // End namespace gold.