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1 27 khays
// gold.cc -- main linker functions
2
 
3
// Copyright 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
4
// Written by Ian Lance Taylor <iant@google.com>.
5
 
6
// This file is part of gold.
7
 
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.
12
 
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.
17
 
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.
22
 
23
#include "gold.h"
24
 
25
#include <cstdlib>
26
#include <cstdio>
27
#include <cstring>
28
#include <unistd.h>
29
#include <algorithm>
30
#include "libiberty.h"
31
 
32
#include "options.h"
33
#include "debug.h"
34
#include "workqueue.h"
35
#include "dirsearch.h"
36
#include "readsyms.h"
37
#include "symtab.h"
38
#include "common.h"
39
#include "object.h"
40
#include "layout.h"
41
#include "reloc.h"
42
#include "defstd.h"
43
#include "plugin.h"
44
#include "gc.h"
45
#include "icf.h"
46
#include "incremental.h"
47
 
48
namespace gold
49
{
50
 
51
class Object;
52
 
53
const char* program_name;
54
 
55
static Task*
56
process_incremental_input(Incremental_binary*, unsigned int, Input_objects*,
57
                          Symbol_table*, Layout*, Dirsearch*, Mapfile*,
58
                          Task_token*, Task_token*);
59
 
60
void
61
gold_exit(bool status)
62
{
63
  if (parameters != NULL
64
      && parameters->options_valid()
65
      && parameters->options().has_plugins())
66
    parameters->options().plugins()->cleanup();
67
  if (!status && parameters != NULL && parameters->options_valid())
68
    unlink_if_ordinary(parameters->options().output_file_name());
69
  exit(status ? EXIT_SUCCESS : EXIT_FAILURE);
70
}
71
 
72
void
73
gold_nomem()
74
{
75
  // We are out of memory, so try hard to print a reasonable message.
76
  // Note that we don't try to translate this message, since the
77
  // translation process itself will require memory.
78
 
79
  // LEN only exists to avoid a pointless warning when write is
80
  // declared with warn_use_result, as when compiling with
81
  // -D_USE_FORTIFY on GNU/Linux.  Casting to void does not appear to
82
  // work, at least not with gcc 4.3.0.
83
 
84
  ssize_t len = write(2, program_name, strlen(program_name));
85
  if (len >= 0)
86
    {
87
      const char* const s = ": out of memory\n";
88
      len = write(2, s, strlen(s));
89
    }
90
  gold_exit(false);
91
}
92
 
93
// Handle an unreachable case.
94
 
95
void
96
do_gold_unreachable(const char* filename, int lineno, const char* function)
97
{
98
  fprintf(stderr, _("%s: internal error in %s, at %s:%d\n"),
99
          program_name, function, filename, lineno);
100
  gold_exit(false);
101
}
102
 
103
// This class arranges to run the functions done in the middle of the
104
// link.  It is just a closure.
105
 
106
class Middle_runner : public Task_function_runner
107
{
108
 public:
109
  Middle_runner(const General_options& options,
110
                const Input_objects* input_objects,
111
                Symbol_table* symtab,
112
                Layout* layout, Mapfile* mapfile)
113
    : options_(options), input_objects_(input_objects), symtab_(symtab),
114
      layout_(layout), mapfile_(mapfile)
115
  { }
116
 
117
  void
118
  run(Workqueue*, const Task*);
119
 
120
 private:
121
  const General_options& options_;
122
  const Input_objects* input_objects_;
123
  Symbol_table* symtab_;
124
  Layout* layout_;
125
  Mapfile* mapfile_;
126
};
127
 
128
void
129
Middle_runner::run(Workqueue* workqueue, const Task* task)
130
{
131
  queue_middle_tasks(this->options_, task, this->input_objects_, this->symtab_,
132
                     this->layout_, workqueue, this->mapfile_);
133
}
134
 
135
// This class arranges the tasks to process the relocs for garbage collection.
136
 
137
class Gc_runner : public Task_function_runner
138
{
139
  public:
140
   Gc_runner(const General_options& options,
141
             const Input_objects* input_objects,
142
             Symbol_table* symtab,
143
             Layout* layout, Mapfile* mapfile)
144
    : options_(options), input_objects_(input_objects), symtab_(symtab),
145
      layout_(layout), mapfile_(mapfile)
146
   { }
147
 
148
  void
149
  run(Workqueue*, const Task*);
150
 
151
 private:
152
  const General_options& options_;
153
  const Input_objects* input_objects_;
154
  Symbol_table* symtab_;
155
  Layout* layout_;
156
  Mapfile* mapfile_;
157
};
158
 
159
void
160
Gc_runner::run(Workqueue* workqueue, const Task* task)
161
{
162
  queue_middle_gc_tasks(this->options_, task, this->input_objects_,
163
                        this->symtab_, this->layout_, workqueue,
164
                        this->mapfile_);
165
}
166
 
167
// Queue up the initial set of tasks for this link job.
168
 
169
void
170
queue_initial_tasks(const General_options& options,
171
                    Dirsearch& search_path,
172
                    const Command_line& cmdline,
173
                    Workqueue* workqueue, Input_objects* input_objects,
174
                    Symbol_table* symtab, Layout* layout, Mapfile* mapfile)
175
{
176
  if (cmdline.begin() == cmdline.end())
177
    {
178
      if (options.printed_version())
179
        gold_exit(true);
180
      gold_fatal(_("no input files"));
181
    }
182
 
183
  int thread_count = options.thread_count_initial();
184
  if (thread_count == 0)
185
    thread_count = cmdline.number_of_input_files();
186
  workqueue->set_thread_count(thread_count);
187
 
188
  // For incremental links, the base output file.
189
  Incremental_binary* ibase = NULL;
190
 
191
  if (parameters->incremental())
192
    {
193
      if (options.relocatable())
194
        gold_error(_("incremental linking is incompatible with -r"));
195
      if (options.emit_relocs())
196
        gold_error(_("incremental linking is incompatible with --emit-relocs"));
197
      if (options.gc_sections())
198
        gold_error(_("incremental linking is incompatible with --gc-sections"));
199
      if (options.icf_enabled())
200
        gold_error(_("incremental linking is incompatible with --icf"));
201
      if (options.has_plugins())
202
        gold_error(_("incremental linking is incompatible with --plugin"));
203
 
204
      if (parameters->incremental_update())
205
        {
206
          Output_file* of = new Output_file(options.output_file_name());
207
          if (of->open_base_file(options.incremental_base(), true))
208
            {
209
              ibase = open_incremental_binary(of);
210
              if (ibase != NULL
211
                  && ibase->check_inputs(cmdline, layout->incremental_inputs()))
212
                ibase->init_layout(layout);
213
              else
214
                {
215
                  delete ibase;
216
                  ibase = NULL;
217
                  of->close();
218
                }
219
            }
220
          if (ibase == NULL)
221
            {
222
              if (set_parameters_incremental_full())
223
                gold_info(_("linking with --incremental-full"));
224
              else
225
                gold_fatal(_("restart link with --incremental-full"));
226
            }
227
        }
228
    }
229
 
230
  // Read the input files.  We have to add the symbols to the symbol
231
  // table in order.  We do this by creating a separate blocker for
232
  // each input file.  We associate the blocker with the following
233
  // input file, to give us a convenient place to delete it.
234
  Task_token* this_blocker = NULL;
235
  if (ibase == NULL)
236
    {
237
      // Normal link.  Queue a Read_symbols task for each input file
238
      // on the command line.
239
      for (Command_line::const_iterator p = cmdline.begin();
240
           p != cmdline.end();
241
           ++p)
242
        {
243
          Task_token* next_blocker = new Task_token(true);
244
          next_blocker->add_blocker();
245
          workqueue->queue(new Read_symbols(input_objects, symtab, layout,
246
                                            &search_path, 0, mapfile, &*p, NULL,
247
                                            NULL, this_blocker, next_blocker));
248
          this_blocker = next_blocker;
249
        }
250
    }
251
  else
252
    {
253
      // Incremental update link.  Process the list of input files
254
      // stored in the base file, and queue a task for each file:
255
      // a Read_symbols task for a changed file, and an Add_symbols task
256
      // for an unchanged file.  We need to mark all the space used by
257
      // unchanged files before we can start any tasks running.
258
      unsigned int input_file_count = ibase->input_file_count();
259
      std::vector<Task*> tasks;
260
      tasks.reserve(input_file_count);
261
      for (unsigned int i = 0; i < input_file_count; ++i)
262
        {
263
          Task_token* next_blocker = new Task_token(true);
264
          next_blocker->add_blocker();
265
          Task* t = process_incremental_input(ibase, i, input_objects, symtab,
266
                                              layout, &search_path, mapfile,
267
                                              this_blocker, next_blocker);
268
          tasks.push_back(t);
269
          this_blocker = next_blocker;
270
        }
271
      // Now we can queue the tasks.
272
      for (unsigned int i = 0; i < tasks.size(); i++)
273
        workqueue->queue(tasks[i]);
274
    }
275
 
276
  if (options.has_plugins())
277
    {
278
      Task_token* next_blocker = new Task_token(true);
279
      next_blocker->add_blocker();
280
      workqueue->queue(new Plugin_hook(options, input_objects, symtab, layout,
281
                                       &search_path, mapfile, this_blocker,
282
                                       next_blocker));
283
      this_blocker = next_blocker;
284
    }
285
 
286
  if (options.relocatable()
287
      && (options.gc_sections() || options.icf_enabled()))
288
    gold_error(_("cannot mix -r with --gc-sections or --icf"));
289
 
290
  if (options.gc_sections() || options.icf_enabled())
291
    {
292
      workqueue->queue(new Task_function(new Gc_runner(options,
293
                                                       input_objects,
294
                                                       symtab,
295
                                                       layout,
296
                                                       mapfile),
297
                                         this_blocker,
298
                                         "Task_function Gc_runner"));
299
    }
300
  else
301
    {
302
      workqueue->queue(new Task_function(new Middle_runner(options,
303
                                                           input_objects,
304
                                                           symtab,
305
                                                           layout,
306
                                                           mapfile),
307
                                         this_blocker,
308
                                         "Task_function Middle_runner"));
309
    }
310
}
311
 
312
// Process an incremental input file: if it is unchanged from the previous
313
// link, return a task to add its symbols from the base file's incremental
314
// info; if it has changed, return a normal Read_symbols task.  We create a
315
// task for every input file, if only to report the file for rebuilding the
316
// incremental info.
317
 
318
static Task*
319
process_incremental_input(Incremental_binary* ibase,
320
                          unsigned int input_file_index,
321
                          Input_objects* input_objects,
322
                          Symbol_table* symtab,
323
                          Layout* layout,
324
                          Dirsearch* search_path,
325
                          Mapfile* mapfile,
326
                          Task_token* this_blocker,
327
                          Task_token* next_blocker)
328
{
329
  const Incremental_binary::Input_reader* input_reader =
330
      ibase->get_input_reader(input_file_index);
331
  Incremental_input_type input_type = input_reader->type();
332
 
333
  // Get the input argument corresponding to this input file, matching on
334
  // the argument serial number.  If the input file cannot be matched
335
  // to an existing input argument, synthesize a new one.
336
  const Input_argument* input_argument =
337
      ibase->get_input_argument(input_file_index);
338
  if (input_argument == NULL)
339
    {
340
      Input_file_argument file(input_reader->filename(),
341
                               Input_file_argument::INPUT_FILE_TYPE_FILE,
342
                               "", false, parameters->options());
343
      Input_argument* arg = new Input_argument(file);
344
      arg->set_script_info(ibase->get_script_info(input_file_index));
345
      input_argument = arg;
346
    }
347
 
348
  gold_debug(DEBUG_INCREMENTAL, "Incremental object: %s, type %d",
349
             input_reader->filename(), input_type);
350
 
351
  if (input_type == INCREMENTAL_INPUT_SCRIPT)
352
    {
353
      // Incremental_binary::check_inputs should have cancelled the
354
      // incremental update if the script has changed.
355
      gold_assert(!ibase->file_has_changed(input_file_index));
356
      return new Check_script(layout, ibase, input_file_index, input_reader,
357
                              this_blocker, next_blocker);
358
    }
359
 
360
  if (input_type == INCREMENTAL_INPUT_ARCHIVE)
361
    {
362
      Incremental_library* lib = ibase->get_library(input_file_index);
363
      gold_assert(lib != NULL);
364
      if (lib->filename() == "/group/"
365
          || !ibase->file_has_changed(input_file_index))
366
        {
367
          // Queue a task to check that no references have been added to any
368
          // of the library's unused symbols.
369
          return new Check_library(symtab, layout, ibase, input_file_index,
370
                                   input_reader, this_blocker, next_blocker);
371
        }
372
      else
373
        {
374
          // Queue a Read_symbols task to process the archive normally.
375
          return new Read_symbols(input_objects, symtab, layout, search_path,
376
                                  0, mapfile, input_argument, NULL, NULL,
377
                                  this_blocker, next_blocker);
378
        }
379
    }
380
 
381
  if (input_type == INCREMENTAL_INPUT_ARCHIVE_MEMBER)
382
    {
383
      // For archive members, check the timestamp of the containing archive.
384
      Incremental_library* lib = ibase->get_library(input_file_index);
385
      gold_assert(lib != NULL);
386
      // Process members of a --start-lib/--end-lib group as normal objects.
387
      if (lib->filename() != "/group/")
388
        {
389
          if (ibase->file_has_changed(lib->input_file_index()))
390
            {
391
              return new Read_member(input_objects, symtab, layout, mapfile,
392
                                     input_reader, this_blocker, next_blocker);
393
            }
394
          else
395
            {
396
              // The previous contributions from this file will be kept.
397
              // Mark the pieces of output sections contributed by this
398
              // object.
399
              ibase->reserve_layout(input_file_index);
400
              Object* obj = make_sized_incremental_object(ibase,
401
                                                          input_file_index,
402
                                                          input_type,
403
                                                          input_reader);
404
              return new Add_symbols(input_objects, symtab, layout,
405
                                     search_path, 0, mapfile, input_argument,
406
                                     obj, lib, NULL, this_blocker,
407
                                     next_blocker);
408
            }
409
        }
410
    }
411
 
412
  // Normal object file or shared library.  Check if the file has changed
413
  // since the last incremental link.
414
  if (ibase->file_has_changed(input_file_index))
415
    {
416
      return new Read_symbols(input_objects, symtab, layout, search_path, 0,
417
                              mapfile, input_argument, NULL, NULL,
418
                              this_blocker, next_blocker);
419
    }
420
  else
421
    {
422
      // The previous contributions from this file will be kept.
423
      // Mark the pieces of output sections contributed by this object.
424
      ibase->reserve_layout(input_file_index);
425
      Object* obj = make_sized_incremental_object(ibase,
426
                                                  input_file_index,
427
                                                  input_type,
428
                                                  input_reader);
429
      return new Add_symbols(input_objects, symtab, layout, search_path, 0,
430
                             mapfile, input_argument, obj, NULL, NULL,
431
                             this_blocker, next_blocker);
432
    }
433
}
434
 
435
// Queue up a set of tasks to be done before queueing the middle set
436
// of tasks.  This is only necessary when garbage collection
437
// (--gc-sections) of unused sections is desired.  The relocs are read
438
// and processed here early to determine the garbage sections before the
439
// relocs can be scanned in later tasks.
440
 
441
void
442
queue_middle_gc_tasks(const General_options& options,
443
                      const Task* ,
444
                      const Input_objects* input_objects,
445
                      Symbol_table* symtab,
446
                      Layout* layout,
447
                      Workqueue* workqueue,
448
                      Mapfile* mapfile)
449
{
450
  // Read_relocs for all the objects must be done and processed to find
451
  // unused sections before any scanning of the relocs can take place.
452
  Task_token* this_blocker = NULL;
453
  for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
454
       p != input_objects->relobj_end();
455
       ++p)
456
    {
457
      Task_token* next_blocker = new Task_token(true);
458
      next_blocker->add_blocker();
459
      workqueue->queue(new Read_relocs(symtab, layout, *p, this_blocker,
460
                                       next_blocker));
461
      this_blocker = next_blocker;
462
    }
463
 
464
  // If we are given only archives in input, we have no regular
465
  // objects and THIS_BLOCKER is NULL here.  Create a dummy
466
  // blocker here so that we can run the middle tasks immediately.
467
  if (this_blocker == NULL)
468
    {
469
      gold_assert(input_objects->number_of_relobjs() == 0);
470
      this_blocker = new Task_token(true);
471
    }
472
 
473
  workqueue->queue(new Task_function(new Middle_runner(options,
474
                                                       input_objects,
475
                                                       symtab,
476
                                                       layout,
477
                                                       mapfile),
478
                                     this_blocker,
479
                                     "Task_function Middle_runner"));
480
}
481
 
482
// Queue up the middle set of tasks.  These are the tasks which run
483
// after all the input objects have been found and all the symbols
484
// have been read, but before we lay out the output file.
485
 
486
void
487
queue_middle_tasks(const General_options& options,
488
                   const Task* task,
489
                   const Input_objects* input_objects,
490
                   Symbol_table* symtab,
491
                   Layout* layout,
492
                   Workqueue* workqueue,
493
                   Mapfile* mapfile)
494
{
495
  // Add any symbols named with -u options to the symbol table.
496
  symtab->add_undefined_symbols_from_command_line(layout);
497
 
498
  // If garbage collection was chosen, relocs have been read and processed
499
  // at this point by pre_middle_tasks.  Layout can then be done for all 
500
  // objects.
501
  if (parameters->options().gc_sections())
502
    {
503
      // Find the start symbol if any.
504
      Symbol* start_sym = symtab->lookup(parameters->entry());
505
      if (start_sym != NULL)
506
        {
507
          bool is_ordinary;
508
          unsigned int shndx = start_sym->shndx(&is_ordinary);
509
          if (is_ordinary)
510
            {
511
              symtab->gc()->worklist().push(
512
                Section_id(start_sym->object(), shndx));
513
            }
514
        }
515
      // Symbols named with -u should not be considered garbage.
516
      symtab->gc_mark_undef_symbols(layout);
517
      gold_assert(symtab->gc() != NULL);
518
      // Do a transitive closure on all references to determine the worklist.
519
      symtab->gc()->do_transitive_closure();
520
    }
521
 
522
  // If identical code folding (--icf) is chosen it makes sense to do it 
523
  // only after garbage collection (--gc-sections) as we do not want to 
524
  // be folding sections that will be garbage.
525
  if (parameters->options().icf_enabled())
526
    {
527
      symtab->icf()->find_identical_sections(input_objects, symtab);
528
    }
529
 
530
  // Call Object::layout for the second time to determine the 
531
  // output_sections for all referenced input sections.  When 
532
  // --gc-sections or --icf is turned on, Object::layout is 
533
  // called twice.  It is called the first time when the 
534
  // symbols are added.
535
  if (parameters->options().gc_sections()
536
      || parameters->options().icf_enabled())
537
    {
538
      for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
539
           p != input_objects->relobj_end();
540
           ++p)
541
        {
542
          Task_lock_obj<Object> tlo(task, *p);
543
          (*p)->layout(symtab, layout, NULL);
544
        }
545
    }
546
 
547
  // Layout deferred objects due to plugins.
548
  if (parameters->options().has_plugins())
549
    {
550
      Plugin_manager* plugins = parameters->options().plugins();
551
      gold_assert(plugins != NULL);
552
      plugins->layout_deferred_objects();
553
    }
554
 
555
  if (parameters->options().gc_sections()
556
      || parameters->options().icf_enabled())
557
    {
558
      for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
559
           p != input_objects->relobj_end();
560
           ++p)
561
        {
562
          // Update the value of output_section stored in rd.
563
          Read_relocs_data* rd = (*p)->get_relocs_data();
564
          for (Read_relocs_data::Relocs_list::iterator q = rd->relocs.begin();
565
               q != rd->relocs.end();
566
               ++q)
567
            {
568
              q->output_section = (*p)->output_section(q->data_shndx);
569
              q->needs_special_offset_handling =
570
                      (*p)->is_output_section_offset_invalid(q->data_shndx);
571
            }
572
        }
573
    }
574
 
575
  // We have to support the case of not seeing any input objects, and
576
  // generate an empty file.  Existing builds depend on being able to
577
  // pass an empty archive to the linker and get an empty object file
578
  // out.  In order to do this we need to use a default target.
579
  if (input_objects->number_of_input_objects() == 0
580
      && layout->incremental_base() == NULL)
581
    parameters_force_valid_target();
582
 
583
  int thread_count = options.thread_count_middle();
584
  if (thread_count == 0)
585
    thread_count = std::max(2, input_objects->number_of_input_objects());
586
  workqueue->set_thread_count(thread_count);
587
 
588
  // Now we have seen all the input files.
589
  const bool doing_static_link =
590
    (!input_objects->any_dynamic()
591
     && !parameters->options().output_is_position_independent());
592
  set_parameters_doing_static_link(doing_static_link);
593
  if (!doing_static_link && options.is_static())
594
    {
595
      // We print out just the first .so we see; there may be others.
596
      gold_assert(input_objects->dynobj_begin() != input_objects->dynobj_end());
597
      gold_error(_("cannot mix -static with dynamic object %s"),
598
                 (*input_objects->dynobj_begin())->name().c_str());
599
    }
600
  if (!doing_static_link && parameters->options().relocatable())
601
    gold_fatal(_("cannot mix -r with dynamic object %s"),
602
               (*input_objects->dynobj_begin())->name().c_str());
603
  if (!doing_static_link
604
      && options.oformat_enum() != General_options::OBJECT_FORMAT_ELF)
605
    gold_fatal(_("cannot use non-ELF output format with dynamic object %s"),
606
               (*input_objects->dynobj_begin())->name().c_str());
607
 
608
  if (parameters->options().relocatable())
609
    {
610
      Input_objects::Relobj_iterator p = input_objects->relobj_begin();
611
      if (p != input_objects->relobj_end())
612
        {
613
          bool uses_split_stack = (*p)->uses_split_stack();
614
          for (++p; p != input_objects->relobj_end(); ++p)
615
            {
616
              if ((*p)->uses_split_stack() != uses_split_stack)
617
                gold_fatal(_("cannot mix split-stack '%s' and "
618
                             "non-split-stack '%s' when using -r"),
619
                           (*input_objects->relobj_begin())->name().c_str(),
620
                           (*p)->name().c_str());
621
            }
622
        }
623
    }
624
 
625
  // For incremental updates, record the existing GOT and PLT entries.
626
  if (parameters->incremental_update())
627
    {
628
      Incremental_binary* ibase = layout->incremental_base();
629
      ibase->process_got_plt(symtab, layout);
630
    }
631
 
632
  if (is_debugging_enabled(DEBUG_SCRIPT))
633
    layout->script_options()->print(stderr);
634
 
635
  // For each dynamic object, record whether we've seen all the
636
  // dynamic objects that it depends upon.
637
  input_objects->check_dynamic_dependencies();
638
 
639
  // See if any of the input definitions violate the One Definition Rule.
640
  // TODO: if this is too slow, do this as a task, rather than inline.
641
  symtab->detect_odr_violations(task, options.output_file_name());
642
 
643
  // Do the --no-undefined-version check.
644
  if (!parameters->options().undefined_version())
645
    {
646
      Script_options* so = layout->script_options();
647
      so->version_script_info()->check_unmatched_names(symtab);
648
    }
649
 
650
  // Create any automatic note sections.
651
  layout->create_notes();
652
 
653
  // Create any output sections required by any linker script.
654
  layout->create_script_sections();
655
 
656
  // Define some sections and symbols needed for a dynamic link.  This
657
  // handles some cases we want to see before we read the relocs.
658
  layout->create_initial_dynamic_sections(symtab);
659
 
660
  // Define symbols from any linker scripts.
661
  layout->define_script_symbols(symtab);
662
 
663
  // Attach sections to segments.
664
  layout->attach_sections_to_segments();
665
 
666
  if (!parameters->options().relocatable())
667
    {
668
      // Predefine standard symbols.
669
      define_standard_symbols(symtab, layout);
670
 
671
      // Define __start and __stop symbols for output sections where
672
      // appropriate.
673
      layout->define_section_symbols(symtab);
674
    }
675
 
676
  // Make sure we have symbols for any required group signatures.
677
  layout->define_group_signatures(symtab);
678
 
679
  Task_token* this_blocker = NULL;
680
 
681
  // Allocate common symbols.  We use a blocker to run this before the
682
  // Scan_relocs tasks, because it writes to the symbol table just as
683
  // they do.
684
  if (parameters->options().define_common())
685
    {
686
      this_blocker = new Task_token(true);
687
      this_blocker->add_blocker();
688
      workqueue->queue(new Allocate_commons_task(symtab, layout, mapfile,
689
                                                 this_blocker));
690
    }
691
 
692
  // If doing garbage collection, the relocations have already been read.
693
  // Otherwise, read and scan the relocations.
694
  if (parameters->options().gc_sections()
695
      || parameters->options().icf_enabled())
696
    {
697
      for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
698
           p != input_objects->relobj_end();
699
           ++p)
700
        {
701
          Task_token* next_blocker = new Task_token(true);
702
          next_blocker->add_blocker();
703
          workqueue->queue(new Scan_relocs(symtab, layout, *p,
704
                                           (*p)->get_relocs_data(),
705
                                           this_blocker, next_blocker));
706
          this_blocker = next_blocker;
707
        }
708
    }
709
  else
710
    {
711
      // Read the relocations of the input files.  We do this to find
712
      // which symbols are used by relocations which require a GOT and/or
713
      // a PLT entry, or a COPY reloc.  When we implement garbage
714
      // collection we will do it here by reading the relocations in a
715
      // breadth first search by references.
716
      //
717
      // We could also read the relocations during the first pass, and
718
      // mark symbols at that time.  That is how the old GNU linker works.
719
      // Doing that is more complex, since we may later decide to discard
720
      // some of the sections, and thus change our minds about the types
721
      // of references made to the symbols.
722
      for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
723
           p != input_objects->relobj_end();
724
           ++p)
725
        {
726
          Task_token* next_blocker = new Task_token(true);
727
          next_blocker->add_blocker();
728
          workqueue->queue(new Read_relocs(symtab, layout, *p, this_blocker,
729
                                           next_blocker));
730
          this_blocker = next_blocker;
731
        }
732
    }
733
 
734
  if (this_blocker == NULL)
735
    {
736
      if (input_objects->number_of_relobjs() == 0)
737
        {
738
          // If we are given only archives in input, we have no regular
739
          // objects and THIS_BLOCKER is NULL here.  Create a dummy
740
          // blocker here so that we can run the layout task immediately.
741
          this_blocker = new Task_token(true);
742
        }
743
      else
744
        {
745
          // If we failed to open any input files, it's possible for
746
          // THIS_BLOCKER to be NULL here.  There's no real point in
747
          // continuing if that happens.
748
          gold_assert(parameters->errors()->error_count() > 0);
749
          gold_exit(false);
750
        }
751
    }
752
 
753
  // When all those tasks are complete, we can start laying out the
754
  // output file.
755
  // TODO(csilvers): figure out a more principled way to get the target
756
  Target* target = const_cast<Target*>(&parameters->target());
757
  workqueue->queue(new Task_function(new Layout_task_runner(options,
758
                                                            input_objects,
759
                                                            symtab,
760
                                                            target,
761
                                                            layout,
762
                                                            mapfile),
763
                                     this_blocker,
764
                                     "Task_function Layout_task_runner"));
765
}
766
 
767
// Queue up the final set of tasks.  This is called at the end of
768
// Layout_task.
769
 
770
void
771
queue_final_tasks(const General_options& options,
772
                  const Input_objects* input_objects,
773
                  const Symbol_table* symtab,
774
                  Layout* layout,
775
                  Workqueue* workqueue,
776
                  Output_file* of)
777
{
778
  int thread_count = options.thread_count_final();
779
  if (thread_count == 0)
780
    thread_count = std::max(2, input_objects->number_of_input_objects());
781
  workqueue->set_thread_count(thread_count);
782
 
783
  bool any_postprocessing_sections = layout->any_postprocessing_sections();
784
 
785
  // Use a blocker to wait until all the input sections have been
786
  // written out.
787
  Task_token* input_sections_blocker = NULL;
788
  if (!any_postprocessing_sections)
789
    {
790
      input_sections_blocker = new Task_token(true);
791
      input_sections_blocker->add_blockers(input_objects->number_of_relobjs());
792
    }
793
 
794
  // Use a blocker to block any objects which have to wait for the
795
  // output sections to complete before they can apply relocations.
796
  Task_token* output_sections_blocker = new Task_token(true);
797
  output_sections_blocker->add_blocker();
798
 
799
  // Use a blocker to block the final cleanup task.
800
  Task_token* final_blocker = new Task_token(true);
801
  // Write_symbols_task, Write_sections_task, Write_data_task,
802
  // Relocate_tasks.
803
  final_blocker->add_blockers(3);
804
  final_blocker->add_blockers(input_objects->number_of_relobjs());
805
  if (!any_postprocessing_sections)
806
    final_blocker->add_blocker();
807
 
808
  // Queue a task to write out the symbol table.
809
  workqueue->queue(new Write_symbols_task(layout,
810
                                          symtab,
811
                                          input_objects,
812
                                          layout->sympool(),
813
                                          layout->dynpool(),
814
                                          of,
815
                                          final_blocker));
816
 
817
  // Queue a task to write out the output sections.
818
  workqueue->queue(new Write_sections_task(layout, of, output_sections_blocker,
819
                                           final_blocker));
820
 
821
  // Queue a task to write out everything else.
822
  workqueue->queue(new Write_data_task(layout, symtab, of, final_blocker));
823
 
824
  // Queue a task for each input object to relocate the sections and
825
  // write out the local symbols.
826
  for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
827
       p != input_objects->relobj_end();
828
       ++p)
829
    workqueue->queue(new Relocate_task(symtab, layout, *p, of,
830
                                       input_sections_blocker,
831
                                       output_sections_blocker,
832
                                       final_blocker));
833
 
834
  // Queue a task to write out the output sections which depend on
835
  // input sections.  If there are any sections which require
836
  // postprocessing, then we need to do this last, since it may resize
837
  // the output file.
838
  if (!any_postprocessing_sections)
839
    {
840
      Task* t = new Write_after_input_sections_task(layout, of,
841
                                                    input_sections_blocker,
842
                                                    final_blocker);
843
      workqueue->queue(t);
844
    }
845
  else
846
    {
847
      Task_token* new_final_blocker = new Task_token(true);
848
      new_final_blocker->add_blocker();
849
      Task* t = new Write_after_input_sections_task(layout, of,
850
                                                    final_blocker,
851
                                                    new_final_blocker);
852
      workqueue->queue(t);
853
      final_blocker = new_final_blocker;
854
    }
855
 
856
  // Queue a task to close the output file.  This will be blocked by
857
  // FINAL_BLOCKER.
858
  workqueue->queue(new Task_function(new Close_task_runner(&options, layout,
859
                                                           of),
860
                                     final_blocker,
861
                                     "Task_function Close_task_runner"));
862
}
863
 
864
} // End namespace gold.

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