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.
64 // LEN only exists to avoid a pointless warning when write is
65 // declared with warn_use_result, as when compiling with
66 // -D_USE_FORTIFY on GNU/Linux. Casting to void does not appear to
67 // work, at least not with gcc 4.3.0.
69 ssize_t len
= write(2, program_name
, strlen(program_name
));
72 const char* const s
= ": out of memory\n";
73 len
= write(2, s
, strlen(s
));
78 // Handle an unreachable case.
81 do_gold_unreachable(const char* filename
, int lineno
, const char* function
)
83 fprintf(stderr
, _("%s: internal error in %s, at %s:%d\n"),
84 program_name
, function
, filename
, lineno
);
88 // This class arranges to run the functions done in the middle of the
89 // link. It is just a closure.
91 class Middle_runner
: public Task_function_runner
94 Middle_runner(const General_options
& options
,
95 const Input_objects
* input_objects
,
98 : options_(options
), input_objects_(input_objects
), symtab_(symtab
),
103 run(Workqueue
*, const Task
*);
106 const General_options
& options_
;
107 const Input_objects
* input_objects_
;
108 Symbol_table
* symtab_
;
113 Middle_runner::run(Workqueue
* workqueue
, const Task
* task
)
115 queue_middle_tasks(this->options_
, task
, this->input_objects_
, this->symtab_
,
116 this->layout_
, workqueue
);
119 // Queue up the initial set of tasks for this link job.
122 queue_initial_tasks(const General_options
& options
,
123 Dirsearch
& search_path
,
124 const Command_line
& cmdline
,
125 Workqueue
* workqueue
, Input_objects
* input_objects
,
126 Symbol_table
* symtab
, Layout
* layout
)
128 if (cmdline
.begin() == cmdline
.end())
129 gold_fatal(_("no input files"));
131 int thread_count
= options
.thread_count_initial();
132 if (thread_count
== 0)
133 thread_count
= cmdline
.number_of_input_files();
134 workqueue
->set_thread_count(thread_count
);
136 // Read the input files. We have to add the symbols to the symbol
137 // table in order. We do this by creating a separate blocker for
138 // each input file. We associate the blocker with the following
139 // input file, to give us a convenient place to delete it.
140 Task_token
* this_blocker
= NULL
;
141 for (Command_line::const_iterator p
= cmdline
.begin();
145 Task_token
* next_blocker
= new Task_token(true);
146 next_blocker
->add_blocker();
147 workqueue
->queue(new Read_symbols(options
, input_objects
, symtab
, layout
,
148 &search_path
, &*p
, NULL
, this_blocker
,
150 this_blocker
= next_blocker
;
153 workqueue
->queue(new Task_function(new Middle_runner(options
,
158 "Task_function Middle_runner"));
161 // Queue up the middle set of tasks. These are the tasks which run
162 // after all the input objects have been found and all the symbols
163 // have been read, but before we lay out the output file.
166 queue_middle_tasks(const General_options
& options
,
168 const Input_objects
* input_objects
,
169 Symbol_table
* symtab
,
171 Workqueue
* workqueue
)
173 // We have to support the case of not seeing any input objects, and
174 // generate an empty file. Existing builds depend on being able to
175 // pass an empty archive to the linker and get an empty object file
176 // out. In order to do this we need to use a default target.
177 if (input_objects
->number_of_input_objects() == 0)
178 set_parameters_target(¶meters
->default_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
->options().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
->options().relocatable())
196 gold_error(_("cannot mix -r with dynamic object %s"),
197 (*input_objects
->dynobj_begin())->name().c_str());
198 if (!doing_static_link
199 && options
.oformat_enum() != General_options::OBJECT_FORMAT_ELF
)
200 gold_fatal(_("cannot use non-ELF output format with dynamic object %s"),
201 (*input_objects
->dynobj_begin())->name().c_str());
203 if (is_debugging_enabled(DEBUG_SCRIPT
))
204 layout
->script_options()->print(stderr
);
206 // For each dynamic object, record whether we've seen all the
207 // dynamic objects that it depends upon.
208 input_objects
->check_dynamic_dependencies();
210 // See if any of the input definitions violate the One Definition Rule.
211 // TODO: if this is too slow, do this as a task, rather than inline.
212 symtab
->detect_odr_violations(task
, options
.output_file_name());
214 // Create any output sections required by any linker script.
215 layout
->create_script_sections();
217 // Define some sections and symbols needed for a dynamic link. This
218 // handles some cases we want to see before we read the relocs.
219 layout
->create_initial_dynamic_sections(symtab
);
221 // Define symbols from any linker scripts.
222 layout
->define_script_symbols(symtab
);
224 // Add any symbols named with -u options to the symbol table.
225 symtab
->add_undefined_symbols_from_command_line();
227 // Attach sections to segments.
228 layout
->attach_sections_to_segments();
230 if (!parameters
->options().relocatable())
232 // Predefine standard symbols.
233 define_standard_symbols(symtab
, layout
);
235 // Define __start and __stop symbols for output sections where
237 layout
->define_section_symbols(symtab
);
240 // Make sure we have symbols for any required group signatures.
241 layout
->define_group_signatures(symtab
);
243 // Read the relocations of the input files. We do this to find
244 // which symbols are used by relocations which require a GOT and/or
245 // a PLT entry, or a COPY reloc. When we implement garbage
246 // collection we will do it here by reading the relocations in a
247 // breadth first search by references.
249 // We could also read the relocations during the first pass, and
250 // mark symbols at that time. That is how the old GNU linker works.
251 // Doing that is more complex, since we may later decide to discard
252 // some of the sections, and thus change our minds about the types
253 // of references made to the symbols.
254 Task_token
* blocker
= new Task_token(true);
255 Task_token
* symtab_lock
= new Task_token(false);
256 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
257 p
!= input_objects
->relobj_end();
260 // We can read and process the relocations in any order. But we
261 // only want one task to write to the symbol table at a time.
262 // So we queue up a task for each object to read the
263 // relocations. That task will in turn queue a task to wait
264 // until it can write to the symbol table.
265 blocker
->add_blocker();
266 workqueue
->queue(new Read_relocs(options
, symtab
, layout
, *p
,
267 symtab_lock
, blocker
));
270 // Allocate common symbols. This requires write access to the
271 // symbol table, but is independent of the relocation processing.
272 if (parameters
->options().define_common())
274 blocker
->add_blocker();
275 workqueue
->queue(new Allocate_commons_task(symtab
, layout
, symtab_lock
,
279 // When all those tasks are complete, we can start laying out the
281 // TODO(csilvers): figure out a more principled way to get the target
282 Target
* target
= const_cast<Target
*>(¶meters
->target());
283 workqueue
->queue(new Task_function(new Layout_task_runner(options
,
289 "Task_function Layout_task_runner"));
292 // Queue up the final set of tasks. This is called at the end of
296 queue_final_tasks(const General_options
& options
,
297 const Input_objects
* input_objects
,
298 const Symbol_table
* symtab
,
300 Workqueue
* workqueue
,
303 int thread_count
= options
.thread_count_final();
304 if (thread_count
== 0)
305 thread_count
= std::max(2, input_objects
->number_of_input_objects());
306 workqueue
->set_thread_count(thread_count
);
308 bool any_postprocessing_sections
= layout
->any_postprocessing_sections();
310 // Use a blocker to wait until all the input sections have been
312 Task_token
* input_sections_blocker
= NULL
;
313 if (!any_postprocessing_sections
)
314 input_sections_blocker
= new Task_token(true);
316 // Use a blocker to block any objects which have to wait for the
317 // output sections to complete before they can apply relocations.
318 Task_token
* output_sections_blocker
= new Task_token(true);
320 // Use a blocker to block the final cleanup task.
321 Task_token
* final_blocker
= new Task_token(true);
323 // Queue a task to write out the symbol table.
324 final_blocker
->add_blocker();
325 workqueue
->queue(new Write_symbols_task(layout
,
333 // Queue a task to write out the output sections.
334 output_sections_blocker
->add_blocker();
335 final_blocker
->add_blocker();
336 workqueue
->queue(new Write_sections_task(layout
, of
, output_sections_blocker
,
339 // Queue a task to write out everything else.
340 final_blocker
->add_blocker();
341 workqueue
->queue(new Write_data_task(layout
, symtab
, of
, final_blocker
));
343 // Queue a task for each input object to relocate the sections and
344 // write out the local symbols.
345 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
346 p
!= input_objects
->relobj_end();
349 if (input_sections_blocker
!= NULL
)
350 input_sections_blocker
->add_blocker();
351 final_blocker
->add_blocker();
352 workqueue
->queue(new Relocate_task(options
, symtab
, layout
, *p
, of
,
353 input_sections_blocker
,
354 output_sections_blocker
,
358 // Queue a task to write out the output sections which depend on
359 // input sections. If there are any sections which require
360 // postprocessing, then we need to do this last, since it may resize
362 if (!any_postprocessing_sections
)
364 final_blocker
->add_blocker();
365 Task
* t
= new Write_after_input_sections_task(layout
, of
,
366 input_sections_blocker
,
372 Task_token
*new_final_blocker
= new Task_token(true);
373 new_final_blocker
->add_blocker();
374 Task
* t
= new Write_after_input_sections_task(layout
, of
,
378 final_blocker
= new_final_blocker
;
381 // Queue a task to close the output file. This will be blocked by
383 workqueue
->queue(new Task_function(new Close_task_runner(&options
, layout
,
386 "Task_function Close_task_runner"));
389 } // End namespace gold.