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 "target-select.h"
35 #include "workqueue.h"
36 #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->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.
64 write(2, program_name, strlen(program_name));
65 const char* const s = ": out of memory\n";
66 write(2, s, strlen(s));
70 // Handle an unreachable case.
73 do_gold_unreachable(const char* filename, int lineno, const char* function)
75 fprintf(stderr, _("%s: internal error in %s, at %s:%d\n"),
76 program_name, function, filename, lineno);
80 // This class arranges to run the functions done in the middle of the
81 // link. It is just a closure.
83 class Middle_runner : public Task_function_runner
86 Middle_runner(const General_options& options,
87 const Input_objects* input_objects,
90 : options_(options), input_objects_(input_objects), symtab_(symtab),
95 run(Workqueue*, const Task*);
98 const General_options& options_;
99 const Input_objects* input_objects_;
100 Symbol_table* symtab_;
105 Middle_runner::run(Workqueue* workqueue, const Task* task)
107 queue_middle_tasks(this->options_, task, this->input_objects_, this->symtab_,
108 this->layout_, workqueue);
111 // Queue up the initial set of tasks for this link job.
114 queue_initial_tasks(const General_options& options,
115 Dirsearch& search_path,
116 const Command_line& cmdline,
117 Workqueue* workqueue, Input_objects* input_objects,
118 Symbol_table* symtab, Layout* layout)
120 if (cmdline.begin() == cmdline.end())
121 gold_fatal(_("no input files"));
123 int thread_count = options.thread_count_initial();
124 if (thread_count == 0)
125 thread_count = cmdline.number_of_input_files();
126 workqueue->set_thread_count(thread_count);
128 // Read the input files. We have to add the symbols to the symbol
129 // table in order. We do this by creating a separate blocker for
130 // each input file. We associate the blocker with the following
131 // input file, to give us a convenient place to delete it.
132 Task_token* this_blocker = NULL;
133 for (Command_line::const_iterator p = cmdline.begin();
137 Task_token* next_blocker = new Task_token(true);
138 next_blocker->add_blocker();
139 workqueue->queue(new Read_symbols(options, input_objects, symtab, layout,
140 &search_path, &*p, NULL, this_blocker,
142 this_blocker = next_blocker;
145 workqueue->queue(new Task_function(new Middle_runner(options,
150 "Task_function Middle_runner"));
153 // Queue up the middle set of tasks. These are the tasks which run
154 // after all the input objects have been found and all the symbols
155 // have been read, but before we lay out the output file.
158 queue_middle_tasks(const General_options& options,
160 const Input_objects* input_objects,
161 Symbol_table* symtab,
163 Workqueue* workqueue)
165 // We have to support the case of not seeing any input objects, and
166 // generate an empty file. Existing builds depend on being able to
167 // pass an empty archive to the linker and get an empty object file
168 // out. In order to do this we need to use a default target.
169 if (input_objects->number_of_input_objects() == 0)
171 // The GOLD_xx macros are defined by the configure script.
172 Target* target = select_target(elfcpp::GOLD_DEFAULT_MACHINE,
174 GOLD_DEFAULT_BIG_ENDIAN,
176 gold_assert(target != NULL);
177 set_parameters_target(target);
180 int thread_count = options.thread_count_middle();
181 if (thread_count == 0)
182 thread_count = std::max(2, input_objects->number_of_input_objects());
183 workqueue->set_thread_count(thread_count);
185 // Now we have seen all the input files.
186 const bool doing_static_link = (!input_objects->any_dynamic()
187 && !parameters->output_is_shared());
188 set_parameters_doing_static_link(doing_static_link);
189 if (!doing_static_link && options.is_static())
191 // We print out just the first .so we see; there may be others.
192 gold_error(_("cannot mix -static with dynamic object %s"),
193 (*input_objects->dynobj_begin())->name().c_str());
195 if (!doing_static_link && parameters->output_is_object())
196 gold_error(_("cannot mix -r with dynamic object %s"),
197 (*input_objects->dynobj_begin())->name().c_str());
199 if (is_debugging_enabled(DEBUG_SCRIPT))
200 layout->script_options()->print(stderr);
202 // For each dynamic object, record whether we've seen all the
203 // dynamic objects that it depends upon.
204 input_objects->check_dynamic_dependencies();
206 // See if any of the input definitions violate the One Definition Rule.
207 // TODO: if this is too slow, do this as a task, rather than inline.
208 symtab->detect_odr_violations(task, options.output_file_name());
210 // Define some sections and symbols needed for a dynamic link. This
211 // handles some cases we want to see before we read the relocs.
212 layout->create_initial_dynamic_sections(symtab);
214 // Define symbols from any linker scripts.
215 layout->define_script_symbols(symtab);
217 if (!parameters->output_is_object())
219 // Predefine standard symbols.
220 define_standard_symbols(symtab, layout);
222 // Define __start and __stop symbols for output sections where
224 layout->define_section_symbols(symtab);
227 // Make sure we have symbols for any required group signatures.
228 layout->define_group_signatures(symtab);
230 // Read the relocations of the input files. We do this to find
231 // which symbols are used by relocations which require a GOT and/or
232 // a PLT entry, or a COPY reloc. When we implement garbage
233 // collection we will do it here by reading the relocations in a
234 // breadth first search by references.
236 // We could also read the relocations during the first pass, and
237 // mark symbols at that time. That is how the old GNU linker works.
238 // Doing that is more complex, since we may later decide to discard
239 // some of the sections, and thus change our minds about the types
240 // of references made to the symbols.
241 Task_token* blocker = new Task_token(true);
242 Task_token* symtab_lock = new Task_token(false);
243 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
244 p != input_objects->relobj_end();
247 // We can read and process the relocations in any order. But we
248 // only want one task to write to the symbol table at a time.
249 // So we queue up a task for each object to read the
250 // relocations. That task will in turn queue a task to wait
251 // until it can write to the symbol table.
252 blocker->add_blocker();
253 workqueue->queue(new Read_relocs(options, symtab, layout, *p,
254 symtab_lock, blocker));
257 // Allocate common symbols. This requires write access to the
258 // symbol table, but is independent of the relocation processing.
259 // FIXME: We should have an option to do this even for a relocatable
261 if (!parameters->output_is_object())
263 blocker->add_blocker();
264 workqueue->queue(new Allocate_commons_task(options, symtab, layout,
265 symtab_lock, blocker));
268 // When all those tasks are complete, we can start laying out the
270 workqueue->queue(new Task_function(new Layout_task_runner(options,
275 "Task_function Layout_task_runner"));
278 // Queue up the final set of tasks. This is called at the end of
282 queue_final_tasks(const General_options& options,
283 const Input_objects* input_objects,
284 const Symbol_table* symtab,
286 Workqueue* workqueue,
289 int thread_count = options.thread_count_final();
290 if (thread_count == 0)
291 thread_count = std::max(2, input_objects->number_of_input_objects());
292 workqueue->set_thread_count(thread_count);
294 bool any_postprocessing_sections = layout->any_postprocessing_sections();
296 // Use a blocker to wait until all the input sections have been
298 Task_token* input_sections_blocker = NULL;
299 if (!any_postprocessing_sections)
300 input_sections_blocker = new Task_token(true);
302 // Use a blocker to block any objects which have to wait for the
303 // output sections to complete before they can apply relocations.
304 Task_token* output_sections_blocker = new Task_token(true);
306 // Use a blocker to block the final cleanup task.
307 Task_token* final_blocker = new Task_token(true);
309 // Queue a task to write out the symbol table.
310 final_blocker->add_blocker();
311 workqueue->queue(new Write_symbols_task(symtab,
318 // Queue a task to write out the output sections.
319 output_sections_blocker->add_blocker();
320 final_blocker->add_blocker();
321 workqueue->queue(new Write_sections_task(layout, of, output_sections_blocker,
324 // Queue a task to write out everything else.
325 final_blocker->add_blocker();
326 workqueue->queue(new Write_data_task(layout, symtab, of, final_blocker));
328 // Queue a task for each input object to relocate the sections and
329 // write out the local symbols.
330 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
331 p != input_objects->relobj_end();
334 if (input_sections_blocker != NULL)
335 input_sections_blocker->add_blocker();
336 final_blocker->add_blocker();
337 workqueue->queue(new Relocate_task(options, symtab, layout, *p, of,
338 input_sections_blocker,
339 output_sections_blocker,
343 // Queue a task to write out the output sections which depend on
344 // input sections. If there are any sections which require
345 // postprocessing, then we need to do this last, since it may resize
347 if (!any_postprocessing_sections)
349 final_blocker->add_blocker();
350 Task* t = new Write_after_input_sections_task(layout, of,
351 input_sections_blocker,
357 Task_token *new_final_blocker = new Task_token(true);
358 new_final_blocker->add_blocker();
359 Task* t = new Write_after_input_sections_task(layout, of,
363 final_blocker = new_final_blocker;
366 // Queue a task to close the output file. This will be blocked by
368 workqueue->queue(new Task_function(new Close_task_runner(of),
370 "Task_function Close_task_runner"));
373 } // End namespace gold.