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.