1 // gold.cc -- main linker functions 2 3 // Copyright (C) 2006-2020 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.number_of_input_files() == 0) 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 // We have to support the case of not seeing any input objects, and 496 // generate an empty file. Existing builds depend on being able to 497 // pass an empty archive to the linker and get an empty object file 498 // out. In order to do this we need to use a default target. 499 if (input_objects->number_of_input_objects() == 0 500 && layout->incremental_base() == NULL) 501 parameters_force_valid_target(); 502 503 // Add any symbols named with -u options to the symbol table. 504 symtab->add_undefined_symbols_from_command_line(layout); 505 506 // If garbage collection was chosen, relocs have been read and processed 507 // at this point by pre_middle_tasks. Layout can then be done for all 508 // objects. 509 if (parameters->options().gc_sections()) 510 { 511 // Find the start symbol if any. 512 Symbol* sym = symtab->lookup(parameters->entry()); 513 if (sym != NULL) 514 symtab->gc_mark_symbol(sym); 515 sym = symtab->lookup(parameters->options().init()); 516 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj()) 517 symtab->gc_mark_symbol(sym); 518 sym = symtab->lookup(parameters->options().fini()); 519 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj()) 520 symtab->gc_mark_symbol(sym); 521 // Symbols named with -u should not be considered garbage. 522 symtab->gc_mark_undef_symbols(layout); 523 gold_assert(symtab->gc() != NULL); 524 // Do a transitive closure on all references to determine the worklist. 525 symtab->gc()->do_transitive_closure(); 526 } 527 528 // If identical code folding (--icf) is chosen it makes sense to do it 529 // only after garbage collection (--gc-sections) as we do not want to 530 // be folding sections that will be garbage. 531 if (parameters->options().icf_enabled()) 532 { 533 symtab->icf()->find_identical_sections(input_objects, symtab); 534 } 535 536 // Call Object::layout for the second time to determine the 537 // output_sections for all referenced input sections. When 538 // --gc-sections or --icf is turned on, or when certain input 539 // sections have to be mapped to unique segments, Object::layout 540 // is called twice. It is called the first time when symbols 541 // are added. 542 if (parameters->options().gc_sections() 543 || parameters->options().icf_enabled() 544 || layout->is_unique_segment_for_sections_specified()) 545 { 546 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 547 p != input_objects->relobj_end(); 548 ++p) 549 { 550 Task_lock_obj<Object> tlo(task, *p); 551 (*p)->layout(symtab, layout, NULL); 552 } 553 } 554 555 // Layout deferred objects due to plugins. 556 if (parameters->options().has_plugins()) 557 { 558 Plugin_manager* plugins = parameters->options().plugins(); 559 gold_assert(plugins != NULL); 560 plugins->layout_deferred_objects(); 561 } 562 563 // Finalize the .eh_frame section. 564 layout->finalize_eh_frame_section(); 565 566 /* If plugins have specified a section order, re-arrange input sections 567 according to a specified section order. If --section-ordering-file is 568 also specified, do not do anything here. */ 569 if (parameters->options().has_plugins() 570 && layout->is_section_ordering_specified() 571 && !parameters->options().section_ordering_file ()) 572 { 573 for (Layout::Section_list::const_iterator p 574 = layout->section_list().begin(); 575 p != layout->section_list().end(); 576 ++p) 577 (*p)->update_section_layout(layout->get_section_order_map()); 578 } 579 580 if (parameters->options().gc_sections() 581 || parameters->options().icf_enabled()) 582 { 583 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 584 p != input_objects->relobj_end(); 585 ++p) 586 { 587 // Update the value of output_section stored in rd. 588 Read_relocs_data* rd = (*p)->get_relocs_data(); 589 for (Read_relocs_data::Relocs_list::iterator q = rd->relocs.begin(); 590 q != rd->relocs.end(); 591 ++q) 592 { 593 q->output_section = (*p)->output_section(q->data_shndx); 594 q->needs_special_offset_handling = 595 (*p)->is_output_section_offset_invalid(q->data_shndx); 596 } 597 } 598 } 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 { 635 const char *name1 636 = (*input_objects->relobj_begin())->name().c_str(); 637 const char *name2 = (*p)->name().c_str(); 638 const char *name_split = uses_split_stack ? name1 : name2; 639 const char *name_nosplit = uses_split_stack ? name2 : name1; 640 gold_fatal(_("cannot mix split-stack '%s' and " 641 "non-split-stack '%s' when using -r"), 642 name_split, name_nosplit); 643 } 644 } 645 } 646 } 647 648 // For incremental updates, record the existing GOT and PLT entries, 649 // and the COPY relocations. 650 if (parameters->incremental_update()) 651 { 652 Incremental_binary* ibase = layout->incremental_base(); 653 ibase->process_got_plt(symtab, layout); 654 ibase->emit_copy_relocs(symtab); 655 } 656 657 if (is_debugging_enabled(DEBUG_SCRIPT)) 658 layout->script_options()->print(stderr); 659 660 // For each dynamic object, record whether we've seen all the 661 // dynamic objects that it depends upon. 662 input_objects->check_dynamic_dependencies(); 663 664 // Do the --no-undefined-version check. 665 if (!parameters->options().undefined_version()) 666 { 667 Script_options* so = layout->script_options(); 668 so->version_script_info()->check_unmatched_names(symtab); 669 } 670 671 // Create any automatic note sections. 672 layout->create_notes(); 673 674 // Create any output sections required by any linker script. 675 layout->create_script_sections(); 676 677 // Define some sections and symbols needed for a dynamic link. This 678 // handles some cases we want to see before we read the relocs. 679 layout->create_initial_dynamic_sections(symtab); 680 681 // Define symbols from any linker scripts. 682 layout->define_script_symbols(symtab); 683 684 // TODO(csilvers): figure out a more principled way to get the target 685 Target* target = const_cast<Target*>(¶meters->target()); 686 687 // Attach sections to segments. 688 layout->attach_sections_to_segments(target); 689 690 if (!parameters->options().relocatable()) 691 { 692 // Predefine standard symbols. 693 define_standard_symbols(symtab, layout); 694 695 // Define __start and __stop symbols for output sections where 696 // appropriate. 697 layout->define_section_symbols(symtab); 698 699 // Define target-specific symbols. 700 target->define_standard_symbols(symtab, layout); 701 } 702 703 // Make sure we have symbols for any required group signatures. 704 layout->define_group_signatures(symtab); 705 706 Task_token* this_blocker = NULL; 707 708 // Allocate common symbols. We use a blocker to run this before the 709 // Scan_relocs tasks, because it writes to the symbol table just as 710 // they do. 711 if (parameters->options().define_common()) 712 { 713 this_blocker = new Task_token(true); 714 this_blocker->add_blocker(); 715 workqueue->queue(new Allocate_commons_task(symtab, layout, mapfile, 716 this_blocker)); 717 } 718 719 // If doing garbage collection, the relocations have already been read. 720 // Otherwise, read and scan the relocations. 721 if (parameters->options().gc_sections() 722 || parameters->options().icf_enabled()) 723 { 724 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 725 p != input_objects->relobj_end(); 726 ++p) 727 { 728 Task_token* next_blocker = new Task_token(true); 729 next_blocker->add_blocker(); 730 workqueue->queue(new Scan_relocs(symtab, layout, *p, 731 (*p)->get_relocs_data(), 732 this_blocker, next_blocker)); 733 this_blocker = next_blocker; 734 } 735 } 736 else 737 { 738 // Read the relocations of the input files. We do this to find 739 // which symbols are used by relocations which require a GOT and/or 740 // a PLT entry, or a COPY reloc. When we implement garbage 741 // collection we will do it here by reading the relocations in a 742 // breadth first search by references. 743 // 744 // We could also read the relocations during the first pass, and 745 // mark symbols at that time. That is how the old GNU linker works. 746 // Doing that is more complex, since we may later decide to discard 747 // some of the sections, and thus change our minds about the types 748 // of references made to the symbols. 749 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 750 p != input_objects->relobj_end(); 751 ++p) 752 { 753 Task_token* next_blocker = new Task_token(true); 754 next_blocker->add_blocker(); 755 workqueue->queue(new Read_relocs(symtab, layout, *p, this_blocker, 756 next_blocker)); 757 this_blocker = next_blocker; 758 } 759 } 760 761 if (this_blocker == NULL) 762 { 763 if (input_objects->number_of_relobjs() == 0) 764 { 765 // If we are given only archives in input, we have no regular 766 // objects and THIS_BLOCKER is NULL here. Create a dummy 767 // blocker here so that we can run the layout task immediately. 768 this_blocker = new Task_token(true); 769 } 770 else 771 { 772 // If we failed to open any input files, it's possible for 773 // THIS_BLOCKER to be NULL here. There's no real point in 774 // continuing if that happens. 775 gold_assert(parameters->errors()->error_count() > 0); 776 gold_exit(GOLD_ERR); 777 } 778 } 779 780 // When all those tasks are complete, we can start laying out the 781 // output file. 782 workqueue->queue(new Task_function(new Layout_task_runner(options, 783 input_objects, 784 symtab, 785 target, 786 layout, 787 mapfile), 788 this_blocker, 789 "Task_function Layout_task_runner")); 790 } 791 792 // Queue up the final set of tasks. This is called at the end of 793 // Layout_task. 794 795 void 796 queue_final_tasks(const General_options& options, 797 const Input_objects* input_objects, 798 const Symbol_table* symtab, 799 Layout* layout, 800 Workqueue* workqueue, 801 Output_file* of) 802 { 803 Timer* timer = parameters->timer(); 804 if (timer != NULL) 805 timer->stamp(1); 806 807 int thread_count = options.thread_count_final(); 808 if (thread_count == 0) 809 thread_count = std::max(2, input_objects->number_of_input_objects()); 810 workqueue->set_thread_count(thread_count); 811 812 bool any_postprocessing_sections = layout->any_postprocessing_sections(); 813 814 // Use a blocker to wait until all the input sections have been 815 // written out. 816 Task_token* input_sections_blocker = NULL; 817 if (!any_postprocessing_sections) 818 { 819 input_sections_blocker = new Task_token(true); 820 // Write_symbols_task, Relocate_tasks. 821 input_sections_blocker->add_blocker(); 822 input_sections_blocker->add_blockers(input_objects->number_of_relobjs()); 823 } 824 825 // Use a blocker to block any objects which have to wait for the 826 // output sections to complete before they can apply relocations. 827 Task_token* output_sections_blocker = new Task_token(true); 828 output_sections_blocker->add_blocker(); 829 830 // Use a blocker to block the final cleanup task. 831 Task_token* final_blocker = new Task_token(true); 832 // Write_symbols_task, Write_sections_task, Write_data_task, 833 // Relocate_tasks. 834 final_blocker->add_blockers(3); 835 final_blocker->add_blockers(input_objects->number_of_relobjs()); 836 if (!any_postprocessing_sections) 837 final_blocker->add_blocker(); 838 839 // Queue a task to write out the symbol table. 840 workqueue->queue(new Write_symbols_task(layout, 841 symtab, 842 input_objects, 843 layout->sympool(), 844 layout->dynpool(), 845 of, 846 final_blocker)); 847 848 // Queue a task to write out the output sections. 849 workqueue->queue(new Write_sections_task(layout, of, output_sections_blocker, 850 input_sections_blocker, 851 final_blocker)); 852 853 // Queue a task to write out everything else. 854 workqueue->queue(new Write_data_task(layout, symtab, of, final_blocker)); 855 856 // Queue a task for each input object to relocate the sections and 857 // write out the local symbols. 858 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 859 p != input_objects->relobj_end(); 860 ++p) 861 workqueue->queue(new Relocate_task(symtab, layout, *p, of, 862 input_sections_blocker, 863 output_sections_blocker, 864 final_blocker)); 865 866 // Queue a task to write out the output sections which depend on 867 // input sections. If there are any sections which require 868 // postprocessing, then we need to do this last, since it may resize 869 // the output file. 870 if (!any_postprocessing_sections) 871 { 872 Task* t = new Write_after_input_sections_task(layout, of, 873 input_sections_blocker, 874 final_blocker); 875 workqueue->queue(t); 876 } 877 else 878 { 879 Task_token* new_final_blocker = new Task_token(true); 880 new_final_blocker->add_blocker(); 881 Task* t = new Write_after_input_sections_task(layout, of, 882 final_blocker, 883 new_final_blocker); 884 workqueue->queue(t); 885 final_blocker = new_final_blocker; 886 } 887 888 // Create tasks for tree-style build ID computation, if necessary. 889 if (strcmp(options.build_id(), "tree") == 0) 890 { 891 // Queue a task to compute the build id. This will be blocked by 892 // FINAL_BLOCKER, and will in turn schedule the task to close 893 // the output file. 894 workqueue->queue(new Task_function(new Build_id_task_runner(&options, 895 layout, 896 of), 897 final_blocker, 898 "Task_function Build_id_task_runner")); 899 } 900 else 901 { 902 // Queue a task to close the output file. This will be blocked by 903 // FINAL_BLOCKER. 904 workqueue->queue(new Task_function(new Close_task_runner(&options, layout, 905 of, NULL, 0), 906 final_blocker, 907 "Task_function Close_task_runner")); 908 } 909 910 } 911 912 } // End namespace gold. 913