1 // gold.cc -- main linker functions 2 3 // Copyright (C) 2006-2016 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 "target-select.h" 34 #include "debug.h" 35 #include "workqueue.h" 36 #include "dirsearch.h" 37 #include "readsyms.h" 38 #include "symtab.h" 39 #include "common.h" 40 #include "object.h" 41 #include "layout.h" 42 #include "reloc.h" 43 #include "defstd.h" 44 #include "plugin.h" 45 #include "gc.h" 46 #include "icf.h" 47 #include "incremental.h" 48 #include "timer.h" 49 50 namespace gold 51 { 52 53 class Object; 54 55 const char* program_name; 56 57 static Task* 58 process_incremental_input(Incremental_binary*, unsigned int, Input_objects*, 59 Symbol_table*, Layout*, Dirsearch*, Mapfile*, 60 Task_token*, Task_token*); 61 62 void 63 gold_exit(Exit_status status) 64 { 65 if (parameters != NULL 66 && parameters->options_valid() 67 && parameters->options().has_plugins()) 68 parameters->options().plugins()->cleanup(); 69 if (status != GOLD_OK && parameters != NULL && parameters->options_valid()) 70 unlink_if_ordinary(parameters->options().output_file_name()); 71 exit(status); 72 } 73 74 void 75 gold_nomem() 76 { 77 // We are out of memory, so try hard to print a reasonable message. 78 // Note that we don't try to translate this message, since the 79 // translation process itself will require memory. 80 81 // LEN only exists to avoid a pointless warning when write is 82 // declared with warn_use_result, as when compiling with 83 // -D_USE_FORTIFY on GNU/Linux. Casting to void does not appear to 84 // work, at least not with gcc 4.3.0. 85 86 ssize_t len = write(2, program_name, strlen(program_name)); 87 if (len >= 0) 88 { 89 const char* const s = ": out of memory\n"; 90 len = write(2, s, strlen(s)); 91 } 92 gold_exit(GOLD_ERR); 93 } 94 95 // Handle an unreachable case. 96 97 void 98 do_gold_unreachable(const char* filename, int lineno, const char* function) 99 { 100 fprintf(stderr, _("%s: internal error in %s, at %s:%d\n"), 101 program_name, function, filename, lineno); 102 gold_exit(GOLD_ERR); 103 } 104 105 // This class arranges to run the functions done in the middle of the 106 // link. It is just a closure. 107 108 class Middle_runner : public Task_function_runner 109 { 110 public: 111 Middle_runner(const General_options& options, 112 const Input_objects* input_objects, 113 Symbol_table* symtab, 114 Layout* layout, Mapfile* mapfile) 115 : options_(options), input_objects_(input_objects), symtab_(symtab), 116 layout_(layout), mapfile_(mapfile) 117 { } 118 119 void 120 run(Workqueue*, const Task*); 121 122 private: 123 const General_options& options_; 124 const Input_objects* input_objects_; 125 Symbol_table* symtab_; 126 Layout* layout_; 127 Mapfile* mapfile_; 128 }; 129 130 void 131 Middle_runner::run(Workqueue* workqueue, const Task* task) 132 { 133 queue_middle_tasks(this->options_, task, this->input_objects_, this->symtab_, 134 this->layout_, workqueue, this->mapfile_); 135 } 136 137 // This class arranges the tasks to process the relocs for garbage collection. 138 139 class Gc_runner : public Task_function_runner 140 { 141 public: 142 Gc_runner(const General_options& options, 143 const Input_objects* input_objects, 144 Symbol_table* symtab, 145 Layout* layout, Mapfile* mapfile) 146 : options_(options), input_objects_(input_objects), symtab_(symtab), 147 layout_(layout), mapfile_(mapfile) 148 { } 149 150 void 151 run(Workqueue*, const Task*); 152 153 private: 154 const General_options& options_; 155 const Input_objects* input_objects_; 156 Symbol_table* symtab_; 157 Layout* layout_; 158 Mapfile* mapfile_; 159 }; 160 161 void 162 Gc_runner::run(Workqueue* workqueue, const Task* task) 163 { 164 queue_middle_gc_tasks(this->options_, task, this->input_objects_, 165 this->symtab_, this->layout_, workqueue, 166 this->mapfile_); 167 } 168 169 // Queue up the initial set of tasks for this link job. 170 171 void 172 queue_initial_tasks(const General_options& options, 173 Dirsearch& search_path, 174 const Command_line& cmdline, 175 Workqueue* workqueue, Input_objects* input_objects, 176 Symbol_table* symtab, Layout* layout, Mapfile* mapfile) 177 { 178 if (cmdline.begin() == cmdline.end()) 179 { 180 bool is_ok = false; 181 if (options.printed_version()) 182 is_ok = true; 183 if (options.print_output_format()) 184 { 185 print_output_format(); 186 is_ok = true; 187 } 188 if (is_ok) 189 gold_exit(GOLD_OK); 190 gold_fatal(_("no input files")); 191 } 192 193 int thread_count = options.thread_count_initial(); 194 if (thread_count == 0) 195 thread_count = cmdline.number_of_input_files(); 196 workqueue->set_thread_count(thread_count); 197 198 // For incremental links, the base output file. 199 Incremental_binary* ibase = NULL; 200 201 if (parameters->incremental_update()) 202 { 203 Output_file* of = new Output_file(options.output_file_name()); 204 if (of->open_base_file(options.incremental_base(), true)) 205 { 206 ibase = open_incremental_binary(of); 207 if (ibase != NULL 208 && ibase->check_inputs(cmdline, layout->incremental_inputs())) 209 ibase->init_layout(layout); 210 else 211 { 212 delete ibase; 213 ibase = NULL; 214 of->close(); 215 } 216 } 217 if (ibase == NULL) 218 { 219 if (set_parameters_incremental_full()) 220 gold_info(_("linking with --incremental-full")); 221 else 222 gold_fallback(_("restart link with --incremental-full")); 223 } 224 } 225 226 // Read the input files. We have to add the symbols to the symbol 227 // table in order. We do this by creating a separate blocker for 228 // each input file. We associate the blocker with the following 229 // input file, to give us a convenient place to delete it. 230 Task_token* this_blocker = NULL; 231 if (ibase == NULL) 232 { 233 // Normal link. Queue a Read_symbols task for each input file 234 // on the command line. 235 for (Command_line::const_iterator p = cmdline.begin(); 236 p != cmdline.end(); 237 ++p) 238 { 239 Task_token* next_blocker = new Task_token(true); 240 next_blocker->add_blocker(); 241 workqueue->queue(new Read_symbols(input_objects, symtab, layout, 242 &search_path, 0, mapfile, &*p, NULL, 243 NULL, this_blocker, next_blocker)); 244 this_blocker = next_blocker; 245 } 246 } 247 else 248 { 249 // Incremental update link. Process the list of input files 250 // stored in the base file, and queue a task for each file: 251 // a Read_symbols task for a changed file, and an Add_symbols task 252 // for an unchanged file. We need to mark all the space used by 253 // unchanged files before we can start any tasks running. 254 unsigned int input_file_count = ibase->input_file_count(); 255 std::vector<Task*> tasks; 256 tasks.reserve(input_file_count); 257 for (unsigned int i = 0; i < input_file_count; ++i) 258 { 259 Task_token* next_blocker = new Task_token(true); 260 next_blocker->add_blocker(); 261 Task* t = process_incremental_input(ibase, i, input_objects, symtab, 262 layout, &search_path, mapfile, 263 this_blocker, next_blocker); 264 tasks.push_back(t); 265 this_blocker = next_blocker; 266 } 267 // Now we can queue the tasks. 268 for (unsigned int i = 0; i < tasks.size(); i++) 269 workqueue->queue(tasks[i]); 270 } 271 272 if (options.has_plugins()) 273 { 274 Task_token* next_blocker = new Task_token(true); 275 next_blocker->add_blocker(); 276 workqueue->queue(new Plugin_hook(options, input_objects, symtab, layout, 277 &search_path, mapfile, this_blocker, 278 next_blocker)); 279 this_blocker = next_blocker; 280 } 281 282 if (options.relocatable() 283 && (options.gc_sections() || options.icf_enabled())) 284 gold_error(_("cannot mix -r with --gc-sections or --icf")); 285 286 if (options.gc_sections() || options.icf_enabled()) 287 { 288 workqueue->queue(new Task_function(new Gc_runner(options, 289 input_objects, 290 symtab, 291 layout, 292 mapfile), 293 this_blocker, 294 "Task_function Gc_runner")); 295 } 296 else 297 { 298 workqueue->queue(new Task_function(new Middle_runner(options, 299 input_objects, 300 symtab, 301 layout, 302 mapfile), 303 this_blocker, 304 "Task_function Middle_runner")); 305 } 306 } 307 308 // Process an incremental input file: if it is unchanged from the previous 309 // link, return a task to add its symbols from the base file's incremental 310 // info; if it has changed, return a normal Read_symbols task. We create a 311 // task for every input file, if only to report the file for rebuilding the 312 // incremental info. 313 314 static Task* 315 process_incremental_input(Incremental_binary* ibase, 316 unsigned int input_file_index, 317 Input_objects* input_objects, 318 Symbol_table* symtab, 319 Layout* layout, 320 Dirsearch* search_path, 321 Mapfile* mapfile, 322 Task_token* this_blocker, 323 Task_token* next_blocker) 324 { 325 const Incremental_binary::Input_reader* input_reader = 326 ibase->get_input_reader(input_file_index); 327 Incremental_input_type input_type = input_reader->type(); 328 329 // Get the input argument corresponding to this input file, matching on 330 // the argument serial number. If the input file cannot be matched 331 // to an existing input argument, synthesize a new one. 332 const Input_argument* input_argument = 333 ibase->get_input_argument(input_file_index); 334 if (input_argument == NULL) 335 { 336 Input_file_argument file(input_reader->filename(), 337 Input_file_argument::INPUT_FILE_TYPE_FILE, 338 "", false, parameters->options()); 339 Input_argument* arg = new Input_argument(file); 340 arg->set_script_info(ibase->get_script_info(input_file_index)); 341 input_argument = arg; 342 } 343 344 gold_debug(DEBUG_INCREMENTAL, "Incremental object: %s, type %d", 345 input_reader->filename(), input_type); 346 347 if (input_type == INCREMENTAL_INPUT_SCRIPT) 348 { 349 // Incremental_binary::check_inputs should have cancelled the 350 // incremental update if the script has changed. 351 gold_assert(!ibase->file_has_changed(input_file_index)); 352 return new Check_script(layout, ibase, input_file_index, input_reader, 353 this_blocker, next_blocker); 354 } 355 356 if (input_type == INCREMENTAL_INPUT_ARCHIVE) 357 { 358 Incremental_library* lib = ibase->get_library(input_file_index); 359 gold_assert(lib != NULL); 360 if (lib->filename() == "/group/" 361 || !ibase->file_has_changed(input_file_index)) 362 { 363 // Queue a task to check that no references have been added to any 364 // of the library's unused symbols. 365 return new Check_library(symtab, layout, ibase, input_file_index, 366 input_reader, this_blocker, next_blocker); 367 } 368 else 369 { 370 // Queue a Read_symbols task to process the archive normally. 371 return new Read_symbols(input_objects, symtab, layout, search_path, 372 0, mapfile, input_argument, NULL, NULL, 373 this_blocker, next_blocker); 374 } 375 } 376 377 if (input_type == INCREMENTAL_INPUT_ARCHIVE_MEMBER) 378 { 379 // For archive members, check the timestamp of the containing archive. 380 Incremental_library* lib = ibase->get_library(input_file_index); 381 gold_assert(lib != NULL); 382 // Process members of a --start-lib/--end-lib group as normal objects. 383 if (lib->filename() != "/group/") 384 { 385 if (ibase->file_has_changed(lib->input_file_index())) 386 { 387 return new Read_member(input_objects, symtab, layout, mapfile, 388 input_reader, this_blocker, next_blocker); 389 } 390 else 391 { 392 // The previous contributions from this file will be kept. 393 // Mark the pieces of output sections contributed by this 394 // object. 395 ibase->reserve_layout(input_file_index); 396 Object* obj = make_sized_incremental_object(ibase, 397 input_file_index, 398 input_type, 399 input_reader); 400 return new Add_symbols(input_objects, symtab, layout, 401 search_path, 0, mapfile, input_argument, 402 obj, lib, NULL, this_blocker, 403 next_blocker); 404 } 405 } 406 } 407 408 // Normal object file or shared library. Check if the file has changed 409 // since the last incremental link. 410 if (ibase->file_has_changed(input_file_index)) 411 { 412 return new Read_symbols(input_objects, symtab, layout, search_path, 0, 413 mapfile, input_argument, NULL, NULL, 414 this_blocker, next_blocker); 415 } 416 else 417 { 418 // The previous contributions from this file will be kept. 419 // Mark the pieces of output sections contributed by this object. 420 ibase->reserve_layout(input_file_index); 421 Object* obj = make_sized_incremental_object(ibase, 422 input_file_index, 423 input_type, 424 input_reader); 425 return new Add_symbols(input_objects, symtab, layout, search_path, 0, 426 mapfile, input_argument, obj, NULL, NULL, 427 this_blocker, next_blocker); 428 } 429 } 430 431 // Queue up a set of tasks to be done before queueing the middle set 432 // of tasks. This is only necessary when garbage collection 433 // (--gc-sections) of unused sections is desired. The relocs are read 434 // and processed here early to determine the garbage sections before the 435 // relocs can be scanned in later tasks. 436 437 void 438 queue_middle_gc_tasks(const General_options& options, 439 const Task* , 440 const Input_objects* input_objects, 441 Symbol_table* symtab, 442 Layout* layout, 443 Workqueue* workqueue, 444 Mapfile* mapfile) 445 { 446 // Read_relocs for all the objects must be done and processed to find 447 // unused sections before any scanning of the relocs can take place. 448 Task_token* this_blocker = NULL; 449 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 450 p != input_objects->relobj_end(); 451 ++p) 452 { 453 Task_token* next_blocker = new Task_token(true); 454 next_blocker->add_blocker(); 455 workqueue->queue(new Read_relocs(symtab, layout, *p, this_blocker, 456 next_blocker)); 457 this_blocker = next_blocker; 458 } 459 460 // If we are given only archives in input, we have no regular 461 // objects and THIS_BLOCKER is NULL here. Create a dummy 462 // blocker here so that we can run the middle tasks immediately. 463 if (this_blocker == NULL) 464 { 465 gold_assert(input_objects->number_of_relobjs() == 0); 466 this_blocker = new Task_token(true); 467 } 468 469 workqueue->queue(new Task_function(new Middle_runner(options, 470 input_objects, 471 symtab, 472 layout, 473 mapfile), 474 this_blocker, 475 "Task_function Middle_runner")); 476 } 477 478 // Queue up the middle set of tasks. These are the tasks which run 479 // after all the input objects have been found and all the symbols 480 // have been read, but before we lay out the output file. 481 482 void 483 queue_middle_tasks(const General_options& options, 484 const Task* task, 485 const Input_objects* input_objects, 486 Symbol_table* symtab, 487 Layout* layout, 488 Workqueue* workqueue, 489 Mapfile* mapfile) 490 { 491 Timer* timer = parameters->timer(); 492 if (timer != NULL) 493 timer->stamp(0); 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* sym = symtab->lookup(parameters->entry()); 505 if (sym != NULL) 506 symtab->gc_mark_symbol(sym); 507 sym = symtab->lookup(parameters->options().init()); 508 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj()) 509 symtab->gc_mark_symbol(sym); 510 sym = symtab->lookup(parameters->options().fini()); 511 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj()) 512 symtab->gc_mark_symbol(sym); 513 // Symbols named with -u should not be considered garbage. 514 symtab->gc_mark_undef_symbols(layout); 515 gold_assert(symtab->gc() != NULL); 516 // Do a transitive closure on all references to determine the worklist. 517 symtab->gc()->do_transitive_closure(); 518 } 519 520 // If identical code folding (--icf) is chosen it makes sense to do it 521 // only after garbage collection (--gc-sections) as we do not want to 522 // be folding sections that will be garbage. 523 if (parameters->options().icf_enabled()) 524 { 525 symtab->icf()->find_identical_sections(input_objects, symtab); 526 } 527 528 // Call Object::layout for the second time to determine the 529 // output_sections for all referenced input sections. When 530 // --gc-sections or --icf is turned on, or when certain input 531 // sections have to be mapped to unique segments, Object::layout 532 // is called twice. It is called the first time when symbols 533 // are added. 534 if (parameters->options().gc_sections() 535 || parameters->options().icf_enabled() 536 || layout->is_unique_segment_for_sections_specified()) 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 // Finalize the .eh_frame section. 556 layout->finalize_eh_frame_section(); 557 558 /* If plugins have specified a section order, re-arrange input sections 559 according to a specified section order. If --section-ordering-file is 560 also specified, do not do anything here. */ 561 if (parameters->options().has_plugins() 562 && layout->is_section_ordering_specified() 563 && !parameters->options().section_ordering_file ()) 564 { 565 for (Layout::Section_list::const_iterator p 566 = layout->section_list().begin(); 567 p != layout->section_list().end(); 568 ++p) 569 (*p)->update_section_layout(layout->get_section_order_map()); 570 } 571 572 if (parameters->options().gc_sections() 573 || parameters->options().icf_enabled()) 574 { 575 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 576 p != input_objects->relobj_end(); 577 ++p) 578 { 579 // Update the value of output_section stored in rd. 580 Read_relocs_data* rd = (*p)->get_relocs_data(); 581 for (Read_relocs_data::Relocs_list::iterator q = rd->relocs.begin(); 582 q != rd->relocs.end(); 583 ++q) 584 { 585 q->output_section = (*p)->output_section(q->data_shndx); 586 q->needs_special_offset_handling = 587 (*p)->is_output_section_offset_invalid(q->data_shndx); 588 } 589 } 590 } 591 592 // We have to support the case of not seeing any input objects, and 593 // generate an empty file. Existing builds depend on being able to 594 // pass an empty archive to the linker and get an empty object file 595 // out. In order to do this we need to use a default target. 596 if (input_objects->number_of_input_objects() == 0 597 && layout->incremental_base() == NULL) 598 parameters_force_valid_target(); 599 600 int thread_count = options.thread_count_middle(); 601 if (thread_count == 0) 602 thread_count = std::max(2, input_objects->number_of_input_objects()); 603 workqueue->set_thread_count(thread_count); 604 605 // Now we have seen all the input files. 606 const bool doing_static_link = 607 (!input_objects->any_dynamic() 608 && !parameters->options().output_is_position_independent()); 609 set_parameters_doing_static_link(doing_static_link); 610 if (!doing_static_link && options.is_static()) 611 { 612 // We print out just the first .so we see; there may be others. 613 gold_assert(input_objects->dynobj_begin() != input_objects->dynobj_end()); 614 gold_error(_("cannot mix -static with dynamic object %s"), 615 (*input_objects->dynobj_begin())->name().c_str()); 616 } 617 if (!doing_static_link && parameters->options().relocatable()) 618 gold_fatal(_("cannot mix -r with dynamic object %s"), 619 (*input_objects->dynobj_begin())->name().c_str()); 620 if (!doing_static_link 621 && options.oformat_enum() != General_options::OBJECT_FORMAT_ELF) 622 gold_fatal(_("cannot use non-ELF output format with dynamic object %s"), 623 (*input_objects->dynobj_begin())->name().c_str()); 624 625 if (parameters->options().relocatable()) 626 { 627 Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 628 if (p != input_objects->relobj_end()) 629 { 630 bool uses_split_stack = (*p)->uses_split_stack(); 631 for (++p; p != input_objects->relobj_end(); ++p) 632 { 633 if ((*p)->uses_split_stack() != uses_split_stack) 634 gold_fatal(_("cannot mix split-stack '%s' and " 635 "non-split-stack '%s' when using -r"), 636 (*input_objects->relobj_begin())->name().c_str(), 637 (*p)->name().c_str()); 638 } 639 } 640 } 641 642 // For incremental updates, record the existing GOT and PLT entries, 643 // and the COPY relocations. 644 if (parameters->incremental_update()) 645 { 646 Incremental_binary* ibase = layout->incremental_base(); 647 ibase->process_got_plt(symtab, layout); 648 ibase->emit_copy_relocs(symtab); 649 } 650 651 if (is_debugging_enabled(DEBUG_SCRIPT)) 652 layout->script_options()->print(stderr); 653 654 // For each dynamic object, record whether we've seen all the 655 // dynamic objects that it depends upon. 656 input_objects->check_dynamic_dependencies(); 657 658 // Do the --no-undefined-version check. 659 if (!parameters->options().undefined_version()) 660 { 661 Script_options* so = layout->script_options(); 662 so->version_script_info()->check_unmatched_names(symtab); 663 } 664 665 // Create any automatic note sections. 666 layout->create_notes(); 667 668 // Create any output sections required by any linker script. 669 layout->create_script_sections(); 670 671 // Define some sections and symbols needed for a dynamic link. This 672 // handles some cases we want to see before we read the relocs. 673 layout->create_initial_dynamic_sections(symtab); 674 675 // Define symbols from any linker scripts. 676 layout->define_script_symbols(symtab); 677 678 // TODO(csilvers): figure out a more principled way to get the target 679 Target* target = const_cast<Target*>(¶meters->target()); 680 681 // Attach sections to segments. 682 layout->attach_sections_to_segments(target); 683 684 if (!parameters->options().relocatable()) 685 { 686 // Predefine standard symbols. 687 define_standard_symbols(symtab, layout); 688 689 // Define __start and __stop symbols for output sections where 690 // appropriate. 691 layout->define_section_symbols(symtab); 692 693 // Define target-specific symbols. 694 target->define_standard_symbols(symtab, layout); 695 } 696 697 // Make sure we have symbols for any required group signatures. 698 layout->define_group_signatures(symtab); 699 700 Task_token* this_blocker = NULL; 701 702 // Allocate common symbols. We use a blocker to run this before the 703 // Scan_relocs tasks, because it writes to the symbol table just as 704 // they do. 705 if (parameters->options().define_common()) 706 { 707 this_blocker = new Task_token(true); 708 this_blocker->add_blocker(); 709 workqueue->queue(new Allocate_commons_task(symtab, layout, mapfile, 710 this_blocker)); 711 } 712 713 // If doing garbage collection, the relocations have already been read. 714 // Otherwise, read and scan the relocations. 715 if (parameters->options().gc_sections() 716 || parameters->options().icf_enabled()) 717 { 718 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 719 p != input_objects->relobj_end(); 720 ++p) 721 { 722 Task_token* next_blocker = new Task_token(true); 723 next_blocker->add_blocker(); 724 workqueue->queue(new Scan_relocs(symtab, layout, *p, 725 (*p)->get_relocs_data(), 726 this_blocker, next_blocker)); 727 this_blocker = next_blocker; 728 } 729 } 730 else 731 { 732 // Read the relocations of the input files. We do this to find 733 // which symbols are used by relocations which require a GOT and/or 734 // a PLT entry, or a COPY reloc. When we implement garbage 735 // collection we will do it here by reading the relocations in a 736 // breadth first search by references. 737 // 738 // We could also read the relocations during the first pass, and 739 // mark symbols at that time. That is how the old GNU linker works. 740 // Doing that is more complex, since we may later decide to discard 741 // some of the sections, and thus change our minds about the types 742 // of references made to the symbols. 743 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 744 p != input_objects->relobj_end(); 745 ++p) 746 { 747 Task_token* next_blocker = new Task_token(true); 748 next_blocker->add_blocker(); 749 workqueue->queue(new Read_relocs(symtab, layout, *p, this_blocker, 750 next_blocker)); 751 this_blocker = next_blocker; 752 } 753 } 754 755 if (this_blocker == NULL) 756 { 757 if (input_objects->number_of_relobjs() == 0) 758 { 759 // If we are given only archives in input, we have no regular 760 // objects and THIS_BLOCKER is NULL here. Create a dummy 761 // blocker here so that we can run the layout task immediately. 762 this_blocker = new Task_token(true); 763 } 764 else 765 { 766 // If we failed to open any input files, it's possible for 767 // THIS_BLOCKER to be NULL here. There's no real point in 768 // continuing if that happens. 769 gold_assert(parameters->errors()->error_count() > 0); 770 gold_exit(GOLD_ERR); 771 } 772 } 773 774 // When all those tasks are complete, we can start laying out the 775 // output file. 776 workqueue->queue(new Task_function(new Layout_task_runner(options, 777 input_objects, 778 symtab, 779 target, 780 layout, 781 mapfile), 782 this_blocker, 783 "Task_function Layout_task_runner")); 784 } 785 786 // Queue up the final set of tasks. This is called at the end of 787 // Layout_task. 788 789 void 790 queue_final_tasks(const General_options& options, 791 const Input_objects* input_objects, 792 const Symbol_table* symtab, 793 Layout* layout, 794 Workqueue* workqueue, 795 Output_file* of) 796 { 797 Timer* timer = parameters->timer(); 798 if (timer != NULL) 799 timer->stamp(1); 800 801 int thread_count = options.thread_count_final(); 802 if (thread_count == 0) 803 thread_count = std::max(2, input_objects->number_of_input_objects()); 804 workqueue->set_thread_count(thread_count); 805 806 bool any_postprocessing_sections = layout->any_postprocessing_sections(); 807 808 // Use a blocker to wait until all the input sections have been 809 // written out. 810 Task_token* input_sections_blocker = NULL; 811 if (!any_postprocessing_sections) 812 { 813 input_sections_blocker = new Task_token(true); 814 // Write_symbols_task, Relocate_tasks. 815 input_sections_blocker->add_blocker(); 816 input_sections_blocker->add_blockers(input_objects->number_of_relobjs()); 817 } 818 819 // Use a blocker to block any objects which have to wait for the 820 // output sections to complete before they can apply relocations. 821 Task_token* output_sections_blocker = new Task_token(true); 822 output_sections_blocker->add_blocker(); 823 824 // Use a blocker to block the final cleanup task. 825 Task_token* final_blocker = new Task_token(true); 826 // Write_symbols_task, Write_sections_task, Write_data_task, 827 // Relocate_tasks. 828 final_blocker->add_blockers(3); 829 final_blocker->add_blockers(input_objects->number_of_relobjs()); 830 if (!any_postprocessing_sections) 831 final_blocker->add_blocker(); 832 833 // Queue a task to write out the symbol table. 834 workqueue->queue(new Write_symbols_task(layout, 835 symtab, 836 input_objects, 837 layout->sympool(), 838 layout->dynpool(), 839 of, 840 final_blocker)); 841 842 // Queue a task to write out the output sections. 843 workqueue->queue(new Write_sections_task(layout, of, output_sections_blocker, 844 input_sections_blocker, 845 final_blocker)); 846 847 // Queue a task to write out everything else. 848 workqueue->queue(new Write_data_task(layout, symtab, of, final_blocker)); 849 850 // Queue a task for each input object to relocate the sections and 851 // write out the local symbols. 852 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 853 p != input_objects->relobj_end(); 854 ++p) 855 workqueue->queue(new Relocate_task(symtab, layout, *p, of, 856 input_sections_blocker, 857 output_sections_blocker, 858 final_blocker)); 859 860 // Queue a task to write out the output sections which depend on 861 // input sections. If there are any sections which require 862 // postprocessing, then we need to do this last, since it may resize 863 // the output file. 864 if (!any_postprocessing_sections) 865 { 866 Task* t = new Write_after_input_sections_task(layout, of, 867 input_sections_blocker, 868 final_blocker); 869 workqueue->queue(t); 870 } 871 else 872 { 873 Task_token* new_final_blocker = new Task_token(true); 874 new_final_blocker->add_blocker(); 875 Task* t = new Write_after_input_sections_task(layout, of, 876 final_blocker, 877 new_final_blocker); 878 workqueue->queue(t); 879 final_blocker = new_final_blocker; 880 } 881 882 // Create tasks for tree-style build ID computation, if necessary. 883 if (strcmp(options.build_id(), "tree") == 0) 884 { 885 // Queue a task to compute the build id. This will be blocked by 886 // FINAL_BLOCKER, and will in turn schedule the task to close 887 // the output file. 888 workqueue->queue(new Task_function(new Build_id_task_runner(&options, 889 layout, 890 of), 891 final_blocker, 892 "Task_function Build_id_task_runner")); 893 } 894 else 895 { 896 // Queue a task to close the output file. This will be blocked by 897 // FINAL_BLOCKER. 898 workqueue->queue(new Task_function(new Close_task_runner(&options, layout, 899 of, NULL, 0), 900 final_blocker, 901 "Task_function Close_task_runner")); 902 } 903 904 } 905 906 } // End namespace gold. 907