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"
47 const char* program_name;
50 gold_exit(bool status)
52 if (!status && parameters != NULL && parameters->options_valid())
53 unlink_if_ordinary(parameters->options().output_file_name());
54 exit(status ? EXIT_SUCCESS : EXIT_FAILURE);
60 // We are out of memory, so try hard to print a reasonable message.
61 // Note that we don't try to translate this message, since the
62 // translation process itself will require memory.
63 write(2, program_name, strlen(program_name));
64 const char* const s = ": out of memory\n";
65 write(2, s, strlen(s));
69 // Handle an unreachable case.
72 do_gold_unreachable(const char* filename, int lineno, const char* function)
74 fprintf(stderr, _("%s: internal error in %s, at %s:%d\n"),
75 program_name, function, filename, lineno);
79 // This class arranges to run the functions done in the middle of the
80 // link. It is just a closure.
82 class Middle_runner : public Task_function_runner
85 Middle_runner(const General_options& options,
86 const Input_objects* input_objects,
89 : options_(options), input_objects_(input_objects), symtab_(symtab),
94 run(Workqueue*, const Task*);
97 const General_options& options_;
98 const Input_objects* input_objects_;
99 Symbol_table* symtab_;
104 Middle_runner::run(Workqueue* workqueue, const Task* task)
106 queue_middle_tasks(this->options_, task, this->input_objects_, this->symtab_,
107 this->layout_, workqueue);
110 // Queue up the initial set of tasks for this link job.
113 queue_initial_tasks(const General_options& options,
114 Dirsearch& search_path,
115 const Command_line& cmdline,
116 Workqueue* workqueue, Input_objects* input_objects,
117 Symbol_table* symtab, Layout* layout)
119 if (cmdline.begin() == cmdline.end())
120 gold_fatal(_("no input files"));
122 int thread_count = options.thread_count_initial();
123 if (thread_count == 0)
124 thread_count = cmdline.number_of_input_files();
125 workqueue->set_thread_count(thread_count);
127 // Read the input files. We have to add the symbols to the symbol
128 // table in order. We do this by creating a separate blocker for
129 // each input file. We associate the blocker with the following
130 // input file, to give us a convenient place to delete it.
131 Task_token* this_blocker = NULL;
132 for (Command_line::const_iterator p = cmdline.begin();
136 Task_token* next_blocker = new Task_token(true);
137 next_blocker->add_blocker();
138 workqueue->queue(new Read_symbols(options, input_objects, symtab, layout,
139 &search_path, &*p, NULL, this_blocker,
141 this_blocker = next_blocker;
144 workqueue->queue(new Task_function(new Middle_runner(options,
149 "Task_function Middle_runner"));
152 // Queue up the middle set of tasks. These are the tasks which run
153 // after all the input objects have been found and all the symbols
154 // have been read, but before we lay out the output file.
157 queue_middle_tasks(const General_options& options,
159 const Input_objects* input_objects,
160 Symbol_table* symtab,
162 Workqueue* workqueue)
164 // We have to support the case of not seeing any input objects, and
165 // generate an empty file. Existing builds depend on being able to
166 // pass an empty archive to the linker and get an empty object file
167 // out. In order to do this we need to use a default target.
168 if (input_objects->number_of_input_objects() == 0)
169 set_parameters_target(¶meters->default_target());
171 int thread_count = options.thread_count_middle();
172 if (thread_count == 0)
173 thread_count = std::max(2, input_objects->number_of_input_objects());
174 workqueue->set_thread_count(thread_count);
176 // Now we have seen all the input files.
177 const bool doing_static_link = (!input_objects->any_dynamic()
178 && !parameters->options().shared());
179 set_parameters_doing_static_link(doing_static_link);
180 if (!doing_static_link && options.is_static())
182 // We print out just the first .so we see; there may be others.
183 gold_error(_("cannot mix -static with dynamic object %s"),
184 (*input_objects->dynobj_begin())->name().c_str());
186 if (!doing_static_link && parameters->options().relocatable())
187 gold_error(_("cannot mix -r with dynamic object %s"),
188 (*input_objects->dynobj_begin())->name().c_str());
189 if (!doing_static_link
190 && options.oformat_enum() != General_options::OBJECT_FORMAT_ELF)
191 gold_fatal(_("cannot use non-ELF output format with dynamic object %s"),
192 (*input_objects->dynobj_begin())->name().c_str());
194 if (is_debugging_enabled(DEBUG_SCRIPT))
195 layout->script_options()->print(stderr);
197 // For each dynamic object, record whether we've seen all the
198 // dynamic objects that it depends upon.
199 input_objects->check_dynamic_dependencies();
201 // See if any of the input definitions violate the One Definition Rule.
202 // TODO: if this is too slow, do this as a task, rather than inline.
203 symtab->detect_odr_violations(task, options.output_file_name());
205 // Create any output sections required by any linker script.
206 layout->create_script_sections();
208 // Define some sections and symbols needed for a dynamic link. This
209 // handles some cases we want to see before we read the relocs.
210 layout->create_initial_dynamic_sections(symtab);
212 // Define symbols from any linker scripts.
213 layout->define_script_symbols(symtab);
215 // Add any symbols named with -u options to the symbol table.
216 symtab->add_undefined_symbols_from_command_line();
218 // Attach sections to segments.
219 layout->attach_sections_to_segments();
221 if (!parameters->options().relocatable())
223 // Predefine standard symbols.
224 define_standard_symbols(symtab, layout);
226 // Define __start and __stop symbols for output sections where
228 layout->define_section_symbols(symtab);
231 // Make sure we have symbols for any required group signatures.
232 layout->define_group_signatures(symtab);
234 // Read the relocations of the input files. We do this to find
235 // which symbols are used by relocations which require a GOT and/or
236 // a PLT entry, or a COPY reloc. When we implement garbage
237 // collection we will do it here by reading the relocations in a
238 // breadth first search by references.
240 // We could also read the relocations during the first pass, and
241 // mark symbols at that time. That is how the old GNU linker works.
242 // Doing that is more complex, since we may later decide to discard
243 // some of the sections, and thus change our minds about the types
244 // of references made to the symbols.
245 Task_token* blocker = new Task_token(true);
246 Task_token* symtab_lock = new Task_token(false);
247 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
248 p != input_objects->relobj_end();
251 // We can read and process the relocations in any order. But we
252 // only want one task to write to the symbol table at a time.
253 // So we queue up a task for each object to read the
254 // relocations. That task will in turn queue a task to wait
255 // until it can write to the symbol table.
256 blocker->add_blocker();
257 workqueue->queue(new Read_relocs(options, symtab, layout, *p,
258 symtab_lock, blocker));
261 // Allocate common symbols. This requires write access to the
262 // symbol table, but is independent of the relocation processing.
263 if (parameters->options().define_common())
265 blocker->add_blocker();
266 workqueue->queue(new Allocate_commons_task(symtab, layout, symtab_lock,
270 // When all those tasks are complete, we can start laying out the
272 // TODO(csilvers): figure out a more principled way to get the target
273 Target* target = const_cast<Target*>(¶meters->target());
274 workqueue->queue(new Task_function(new Layout_task_runner(options,
280 "Task_function Layout_task_runner"));
283 // Queue up the final set of tasks. This is called at the end of
287 queue_final_tasks(const General_options& options,
288 const Input_objects* input_objects,
289 const Symbol_table* symtab,
291 Workqueue* workqueue,
294 int thread_count = options.thread_count_final();
295 if (thread_count == 0)
296 thread_count = std::max(2, input_objects->number_of_input_objects());
297 workqueue->set_thread_count(thread_count);
299 bool any_postprocessing_sections = layout->any_postprocessing_sections();
301 // Use a blocker to wait until all the input sections have been
303 Task_token* input_sections_blocker = NULL;
304 if (!any_postprocessing_sections)
305 input_sections_blocker = new Task_token(true);
307 // Use a blocker to block any objects which have to wait for the
308 // output sections to complete before they can apply relocations.
309 Task_token* output_sections_blocker = new Task_token(true);
311 // Use a blocker to block the final cleanup task.
312 Task_token* final_blocker = new Task_token(true);
314 // Queue a task to write out the symbol table.
315 final_blocker->add_blocker();
316 workqueue->queue(new Write_symbols_task(layout,
324 // Queue a task to write out the output sections.
325 output_sections_blocker->add_blocker();
326 final_blocker->add_blocker();
327 workqueue->queue(new Write_sections_task(layout, of, output_sections_blocker,
330 // Queue a task to write out everything else.
331 final_blocker->add_blocker();
332 workqueue->queue(new Write_data_task(layout, symtab, of, final_blocker));
334 // Queue a task for each input object to relocate the sections and
335 // write out the local symbols.
336 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
337 p != input_objects->relobj_end();
340 if (input_sections_blocker != NULL)
341 input_sections_blocker->add_blocker();
342 final_blocker->add_blocker();
343 workqueue->queue(new Relocate_task(options, symtab, layout, *p, of,
344 input_sections_blocker,
345 output_sections_blocker,
349 // Queue a task to write out the output sections which depend on
350 // input sections. If there are any sections which require
351 // postprocessing, then we need to do this last, since it may resize
353 if (!any_postprocessing_sections)
355 final_blocker->add_blocker();
356 Task* t = new Write_after_input_sections_task(layout, of,
357 input_sections_blocker,
363 Task_token *new_final_blocker = new Task_token(true);
364 new_final_blocker->add_blocker();
365 Task* t = new Write_after_input_sections_task(layout, of,
369 final_blocker = new_final_blocker;
372 // Queue a task to close the output file. This will be blocked by
374 workqueue->queue(new Task_function(new Close_task_runner(&options, layout,
377 "Task_function Close_task_runner"));
380 } // End namespace gold.