gold/incremental.cc

   1 // inremental.cc -- incremental linking support for gold
   2
   3 // Copyright 2009, 2010 Free Software Foundation, Inc.
   4 // Written by Mikolaj Zalewski <mikolajz@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 <cstdarg>
  26 #include "libiberty.h"
  27
  28 #include "elfcpp.h"
  29 #include "output.h"
  30 #include "symtab.h"
  31 #include "incremental.h"
  32 #include "archive.h"
  33 #include "output.h"
  34 #include "target-select.h"
  35 #include "target.h"
  36
  37 namespace gold {
  38
  39 // Version information. Will change frequently during the development, later
  40 // we could think about backward (and forward?) compatibility.
  41 const unsigned int INCREMENTAL_LINK_VERSION = 1;
  42
  43 // This class manages the .gnu_incremental_inputs section, which holds
  44 // the header information, a directory of input files, and separate
  45 // entries for each input file.
  46
  47 template<int size, bool big_endian>
  48 class Output_section_incremental_inputs : public Output_section_data
  49 {
  50  public:
  51   Output_section_incremental_inputs(const Incremental_inputs* inputs,
  52                                     const Symbol_table* symtab)
  53     : Output_section_data(size / 8), inputs_(inputs), symtab_(symtab)
  54   { }
  55
  56  protected:
  57   // Set the final data size.
  58   void
  59   set_final_data_size();
  60
  61   // Write the data to the file.
  62   void
  63   do_write(Output_file*);
  64
  65   // Write to a map file.
  66   void
  67   do_print_to_mapfile(Mapfile* mapfile) const
  68   { mapfile->print_output_data(this, _("** incremental_inputs")); }
  69
  70  private:
  71   // Write the section header.
  72   unsigned char*
  73   write_header(unsigned char* pov, unsigned int input_file_count,
  74                section_offset_type command_line_offset);
  75
  76   // Write the input file entries.
  77   unsigned char*
  78   write_input_files(unsigned char* oview, unsigned char* pov,
  79                     Stringpool* strtab);
  80
  81   // Write the supplemental information blocks.
  82   unsigned char*
  83   write_info_blocks(unsigned char* oview, unsigned char* pov,
  84                     Stringpool* strtab, unsigned int* global_syms,
  85                     unsigned int global_sym_count);
  86
  87   // Write the contents of the .gnu_incremental_symtab section.
  88   void
  89   write_symtab(unsigned char* pov, unsigned int* global_syms,
  90                unsigned int global_sym_count);
  91
  92   // Write the contents of the .gnu_incremental_got_plt section.
  93   void
  94   write_got_plt(unsigned char* pov, off_t view_size);
  95
  96   // Typedefs for writing the data to the output sections.
  97   typedef elfcpp::Swap<size, big_endian> Swap;
  98   typedef elfcpp::Swap<16, big_endian> Swap16;
  99   typedef elfcpp::Swap<32, big_endian> Swap32;
 100   typedef elfcpp::Swap<64, big_endian> Swap64;
 101
 102   // Sizes of various structures.
 103   static const int sizeof_addr = size / 8;
 104   static const int header_size = 16;
 105   static const int input_entry_size = 24;
 106
 107   // The Incremental_inputs object.
 108   const Incremental_inputs* inputs_;
 109
 110   // The symbol table.
 111   const Symbol_table* symtab_;
 112 };
 113
 114 // Inform the user why we don't do an incremental link.  Not called in
 115 // the obvious case of missing output file.  TODO: Is this helpful?
 116
 117 void
 118 vexplain_no_incremental(const char* format, va_list args)
 119 {
 120   char* buf = NULL;
 121   if (vasprintf(&buf, format, args) < 0)
 122     gold_nomem();
 123   gold_info(_("the link might take longer: "
 124               "cannot perform incremental link: %s"), buf);
 125   free(buf);
 126 }
 127
 128 void
 129 explain_no_incremental(const char* format, ...)
 130 {
 131   va_list args;
 132   va_start(args, format);
 133   vexplain_no_incremental(format, args);
 134   va_end(args);
 135 }
 136
 137 // Report an error.
 138
 139 void
 140 Incremental_binary::error(const char* format, ...) const
 141 {
 142   va_list args;
 143   va_start(args, format);
 144   // Current code only checks if the file can be used for incremental linking,
 145   // so errors shouldn't fail the build, but only result in a fallback to a
 146   // full build.
 147   // TODO: when we implement incremental editing of the file, we may need a
 148   // flag that will cause errors to be treated seriously.
 149   vexplain_no_incremental(format, args);
 150   va_end(args);
 151 }
 152
 153 // Find the .gnu_incremental_inputs section and related sections.
 154
 155 template<int size, bool big_endian>
 156 bool
 157 Sized_incremental_binary<size, big_endian>::do_find_incremental_inputs_sections(
 158     unsigned int* p_inputs_shndx,
 159     unsigned int* p_symtab_shndx,
 160     unsigned int* p_relocs_shndx,
 161     unsigned int* p_got_plt_shndx,
 162     unsigned int* p_strtab_shndx)
 163 {
 164   unsigned int inputs_shndx =
 165       this->elf_file_.find_section_by_type(elfcpp::SHT_GNU_INCREMENTAL_INPUTS);
 166   if (inputs_shndx == elfcpp::SHN_UNDEF)  // Not found.
 167     return false;
 168
 169   unsigned int symtab_shndx =
 170       this->elf_file_.find_section_by_type(elfcpp::SHT_GNU_INCREMENTAL_SYMTAB);
 171   if (symtab_shndx == elfcpp::SHN_UNDEF)  // Not found.
 172     return false;
 173   if (this->elf_file_.section_link(symtab_shndx) != inputs_shndx)
 174     return false;
 175
 176   unsigned int relocs_shndx =
 177       this->elf_file_.find_section_by_type(elfcpp::SHT_GNU_INCREMENTAL_RELOCS);
 178   if (relocs_shndx == elfcpp::SHN_UNDEF)  // Not found.
 179     return false;
 180   if (this->elf_file_.section_link(relocs_shndx) != inputs_shndx)
 181     return false;
 182
 183   unsigned int got_plt_shndx =
 184       this->elf_file_.find_section_by_type(elfcpp::SHT_GNU_INCREMENTAL_GOT_PLT);
 185   if (got_plt_shndx == elfcpp::SHN_UNDEF)  // Not found.
 186     return false;
 187   if (this->elf_file_.section_link(got_plt_shndx) != inputs_shndx)
 188     return false;
 189
 190   unsigned int strtab_shndx = this->elf_file_.section_link(inputs_shndx);
 191   if (strtab_shndx == elfcpp::SHN_UNDEF
 192       || strtab_shndx > this->elf_file_.shnum()
 193       || this->elf_file_.section_type(strtab_shndx) != elfcpp::SHT_STRTAB)
 194     return false;
 195
 196   if (p_inputs_shndx != NULL)
 197     *p_inputs_shndx = inputs_shndx;
 198   if (p_symtab_shndx != NULL)
 199     *p_symtab_shndx = symtab_shndx;
 200   if (p_relocs_shndx != NULL)
 201     *p_relocs_shndx = relocs_shndx;
 202   if (p_got_plt_shndx != NULL)
 203     *p_got_plt_shndx = got_plt_shndx;
 204   if (p_strtab_shndx != NULL)
 205     *p_strtab_shndx = strtab_shndx;
 206   return true;
 207 }
 208
 209 // Determine whether an incremental link based on the existing output file
 210 // can be done.
 211
 212 template<int size, bool big_endian>
 213 bool
 214 Sized_incremental_binary<size, big_endian>::do_check_inputs(
 215     Incremental_inputs* incremental_inputs)
 216 {
 217   unsigned int inputs_shndx;
 218   unsigned int symtab_shndx;
 219   unsigned int relocs_shndx;
 220   unsigned int plt_got_shndx;
 221   unsigned int strtab_shndx;
 222
 223   if (!do_find_incremental_inputs_sections(&inputs_shndx, &symtab_shndx,
 224                                            &relocs_shndx, &plt_got_shndx,
 225                                            &strtab_shndx))
 226     {
 227       explain_no_incremental(_("no incremental data from previous build"));
 228       return false;
 229     }
 230
 231   Location inputs_location(this->elf_file_.section_contents(inputs_shndx));
 232   Location symtab_location(this->elf_file_.section_contents(symtab_shndx));
 233   Location relocs_location(this->elf_file_.section_contents(relocs_shndx));
 234   Location strtab_location(this->elf_file_.section_contents(strtab_shndx));
 235
 236   View inputs_view(view(inputs_location));
 237   View symtab_view(view(symtab_location));
 238   View relocs_view(view(relocs_location));
 239   View strtab_view(view(strtab_location));
 240
 241   elfcpp::Elf_strtab strtab(strtab_view.data(), strtab_location.data_size);
 242
 243   Incremental_inputs_reader<size, big_endian>
 244       incoming_inputs(inputs_view.data(), strtab);
 245
 246   if (incoming_inputs.version() != INCREMENTAL_LINK_VERSION)
 247     {
 248       explain_no_incremental(_("different version of incremental build data"));
 249       return false;
 250     }
 251
 252   if (incremental_inputs->command_line() != incoming_inputs.command_line())
 253     {
 254       explain_no_incremental(_("command line changed"));
 255       return false;
 256     }
 257
 258   // TODO: compare incremental_inputs->inputs() with entries in data_view.
 259
 260   return true;
 261 }
 262
 263 namespace
 264 {
 265
 266 // Create a Sized_incremental_binary object of the specified size and
 267 // endianness. Fails if the target architecture is not supported.
 268
 269 template<int size, bool big_endian>
 270 Incremental_binary*
 271 make_sized_incremental_binary(Output_file* file,
 272                               const elfcpp::Ehdr<size, big_endian>& ehdr)
 273 {
 274   Target* target = select_target(ehdr.get_e_machine(), size, big_endian,
 275                                  ehdr.get_e_ident()[elfcpp::EI_OSABI],
 276                                  ehdr.get_e_ident()[elfcpp::EI_ABIVERSION]);
 277   if (target == NULL)
 278     {
 279       explain_no_incremental(_("unsupported ELF machine number %d"),
 280                ehdr.get_e_machine());
 281       return NULL;
 282     }
 283
 284   if (!parameters->target_valid())
 285     set_parameters_target(target);
 286   else if (target != &parameters->target())
 287     gold_error(_("%s: incompatible target"), file->filename());
 288
 289   return new Sized_incremental_binary<size, big_endian>(file, ehdr, target);
 290 }
 291
 292 }  // End of anonymous namespace.
 293
 294 // Create an Incremental_binary object for FILE.  Returns NULL is this is not
 295 // possible, e.g. FILE is not an ELF file or has an unsupported target.  FILE
 296 // should be opened.
 297
 298 Incremental_binary*
 299 open_incremental_binary(Output_file* file)
 300 {
 301   off_t filesize = file->filesize();
 302   int want = elfcpp::Elf_recognizer::max_header_size;
 303   if (filesize < want)
 304     want = filesize;
 305
 306   const unsigned char* p = file->get_input_view(0, want);
 307   if (!elfcpp::Elf_recognizer::is_elf_file(p, want))
 308     {
 309       explain_no_incremental(_("output is not an ELF file."));
 310       return NULL;
 311     }
 312
 313   int size = 0;
 314   bool big_endian = false;
 315   std::string error;
 316   if (!elfcpp::Elf_recognizer::is_valid_header(p, want, &size, &big_endian,
 317                                                &error))
 318     {
 319       explain_no_incremental(error.c_str());
 320       return NULL;
 321     }
 322
 323   Incremental_binary* result = NULL;
 324   if (size == 32)
 325     {
 326       if (big_endian)
 327         {
 328 #ifdef HAVE_TARGET_32_BIG
 329           result = make_sized_incremental_binary<32, true>(
 330               file, elfcpp::Ehdr<32, true>(p));
 331 #else
 332           explain_no_incremental(_("unsupported file: 32-bit, big-endian"));
 333 #endif
 334         }
 335       else
 336         {
 337 #ifdef HAVE_TARGET_32_LITTLE
 338           result = make_sized_incremental_binary<32, false>(
 339               file, elfcpp::Ehdr<32, false>(p));
 340 #else
 341           explain_no_incremental(_("unsupported file: 32-bit, little-endian"));
 342 #endif
 343         }
 344     }
 345   else if (size == 64)
 346     {
 347       if (big_endian)
 348         {
 349 #ifdef HAVE_TARGET_64_BIG
 350           result = make_sized_incremental_binary<64, true>(
 351               file, elfcpp::Ehdr<64, true>(p));
 352 #else
 353           explain_no_incremental(_("unsupported file: 64-bit, big-endian"));
 354 #endif
 355         }
 356       else
 357         {
 358 #ifdef HAVE_TARGET_64_LITTLE
 359           result = make_sized_incremental_binary<64, false>(
 360               file, elfcpp::Ehdr<64, false>(p));
 361 #else
 362           explain_no_incremental(_("unsupported file: 64-bit, little-endian"));
 363 #endif
 364         }
 365     }
 366   else
 367     gold_unreachable();
 368
 369   return result;
 370 }
 371
 372 // Analyzes the output file to check if incremental linking is possible and
 373 // (to be done) what files need to be relinked.
 374
 375 bool
 376 Incremental_checker::can_incrementally_link_output_file()
 377 {
 378   Output_file output(this->output_name_);
 379   if (!output.open_for_modification())
 380     return false;
 381   Incremental_binary* binary = open_incremental_binary(&output);
 382   if (binary == NULL)
 383     return false;
 384   return binary->check_inputs(this->incremental_inputs_);
 385 }
 386
 387 // Class Incremental_inputs.
 388
 389 // Add the command line to the string table, setting
 390 // command_line_key_.  In incremental builds, the command line is
 391 // stored in .gnu_incremental_inputs so that the next linker run can
 392 // check if the command line options didn't change.
 393
 394 void
 395 Incremental_inputs::report_command_line(int argc, const char* const* argv)
 396 {
 397   // Always store 'gold' as argv[0] to avoid a full relink if the user used a
 398   // different path to the linker.
 399   std::string args("gold");
 400   // Copied from collect_argv in main.cc.
 401   for (int i = 1; i < argc; ++i)
 402     {
 403       // Adding/removing these options should not result in a full relink.
 404       if (strcmp(argv[i], "--incremental-changed") == 0
 405           || strcmp(argv[i], "--incremental-unchanged") == 0
 406           || strcmp(argv[i], "--incremental-unknown") == 0)
 407         continue;
 408
 409       args.append(" '");
 410       // Now append argv[i], but with all single-quotes escaped
 411       const char* argpos = argv[i];
 412       while (1)
 413         {
 414           const int len = strcspn(argpos, "'");
 415           args.append(argpos, len);
 416           if (argpos[len] == '\0')
 417             break;
 418           args.append("'\"'\"'");
 419           argpos += len + 1;
 420         }
 421       args.append("'");
 422     }
 423
 424   this->command_line_ = args;
 425   this->strtab_->add(this->command_line_.c_str(), false,
 426                      &this->command_line_key_);
 427 }
 428
 429 // Record the input archive file ARCHIVE.  This is called by the
 430 // Add_archive_symbols task before determining which archive members
 431 // to include.  We create the Incremental_archive_entry here and
 432 // attach it to the Archive, but we do not add it to the list of
 433 // input objects until report_archive_end is called.
 434
 435 void
 436 Incremental_inputs::report_archive_begin(Archive* arch)
 437 {
 438   Stringpool::Key filename_key;
 439   Timespec mtime = arch->file().get_mtime();
 440
 441   this->strtab_->add(arch->filename().c_str(), false, &filename_key);
 442   Incremental_archive_entry* entry =
 443       new Incremental_archive_entry(filename_key, arch, mtime);
 444   arch->set_incremental_info(entry);
 445 }
 446
 447 // Finish recording the input archive file ARCHIVE.  This is called by the
 448 // Add_archive_symbols task after determining which archive members
 449 // to include.
 450
 451 void
 452 Incremental_inputs::report_archive_end(Archive* arch)
 453 {
 454   Incremental_archive_entry* entry = arch->incremental_info();
 455
 456   gold_assert(entry != NULL);
 457
 458   // Collect unused global symbols.
 459   for (Archive::Unused_symbol_iterator p = arch->unused_symbols_begin();
 460        p != arch->unused_symbols_end();
 461        ++p)
 462     {
 463       Stringpool::Key symbol_key;
 464       this->strtab_->add(*p, true, &symbol_key);
 465       entry->add_unused_global_symbol(symbol_key);
 466     }
 467   this->inputs_.push_back(entry);
 468 }
 469
 470 // Record the input object file OBJ.  If ARCH is not NULL, attach
 471 // the object file to the archive.  This is called by the
 472 // Add_symbols task after finding out the type of the file.
 473
 474 void
 475 Incremental_inputs::report_object(Object* obj, Archive* arch)
 476 {
 477   Stringpool::Key filename_key;
 478   Timespec mtime = obj->input_file()->file().get_mtime();
 479
 480   this->strtab_->add(obj->name().c_str(), false, &filename_key);
 481   Incremental_object_entry* obj_entry =
 482       new Incremental_object_entry(filename_key, obj, mtime);
 483   this->inputs_.push_back(obj_entry);
 484
 485   if (arch != NULL)
 486     {
 487       Incremental_archive_entry* arch_entry = arch->incremental_info();
 488       gold_assert(arch_entry != NULL);
 489       arch_entry->add_object(obj_entry);
 490     }
 491
 492   this->current_object_ = obj;
 493   this->current_object_entry_ = obj_entry;
 494 }
 495
 496 // Record the input object file OBJ.  If ARCH is not NULL, attach
 497 // the object file to the archive.  This is called by the
 498 // Add_symbols task after finding out the type of the file.
 499
 500 void
 501 Incremental_inputs::report_input_section(Object* obj, unsigned int shndx,
 502                                          const char* name, off_t sh_size)
 503 {
 504   Stringpool::Key key = 0;
 505
 506   if (name != NULL)
 507       this->strtab_->add(name, true, &key);
 508
 509   gold_assert(obj == this->current_object_);
 510   this->current_object_entry_->add_input_section(shndx, key, sh_size);
 511 }
 512
 513 // Record that the input argument INPUT is a script SCRIPT.  This is
 514 // called by read_script after parsing the script and reading the list
 515 // of inputs added by this script.
 516
 517 void
 518 Incremental_inputs::report_script(const std::string& filename,
 519                                   Script_info* script, Timespec mtime)
 520 {
 521   Stringpool::Key filename_key;
 522
 523   this->strtab_->add(filename.c_str(), false, &filename_key);
 524   Incremental_script_entry* entry =
 525       new Incremental_script_entry(filename_key, script, mtime);
 526   this->inputs_.push_back(entry);
 527 }
 528
 529 // Finalize the incremental link information.  Called from
 530 // Layout::finalize.
 531
 532 void
 533 Incremental_inputs::finalize()
 534 {
 535   // Finalize the string table.
 536   this->strtab_->set_string_offsets();
 537 }
 538
 539 // Create the .gnu_incremental_inputs, _symtab, and _relocs input sections.
 540
 541 void
 542 Incremental_inputs::create_data_sections(Symbol_table* symtab)
 543 {
 544   switch (parameters->size_and_endianness())
 545     {
 546 #ifdef HAVE_TARGET_32_LITTLE
 547     case Parameters::TARGET_32_LITTLE:
 548       this->inputs_section_ =
 549           new Output_section_incremental_inputs<32, false>(this, symtab);
 550       break;
 551 #endif
 552 #ifdef HAVE_TARGET_32_BIG
 553     case Parameters::TARGET_32_BIG:
 554       this->inputs_section_ =
 555           new Output_section_incremental_inputs<32, true>(this, symtab);
 556       break;
 557 #endif
 558 #ifdef HAVE_TARGET_64_LITTLE
 559     case Parameters::TARGET_64_LITTLE:
 560       this->inputs_section_ =
 561           new Output_section_incremental_inputs<64, false>(this, symtab);
 562       break;
 563 #endif
 564 #ifdef HAVE_TARGET_64_BIG
 565     case Parameters::TARGET_64_BIG:
 566       this->inputs_section_ =
 567           new Output_section_incremental_inputs<64, true>(this, symtab);
 568       break;
 569 #endif
 570     default:
 571       gold_unreachable();
 572     }
 573   this->symtab_section_ = new Output_data_space(4, "** incremental_symtab");
 574   this->relocs_section_ = new Output_data_space(4, "** incremental_relocs");
 575   this->got_plt_section_ = new Output_data_space(4, "** incremental_got_plt");
 576 }
 577
 578 // Return the sh_entsize value for the .gnu_incremental_relocs section.
 579 unsigned int
 580 Incremental_inputs::relocs_entsize() const
 581 {
 582   return 8 + 2 * parameters->target().get_size() / 8;
 583 }
 584
 585 // Class Output_section_incremental_inputs.
 586
 587 // Finalize the offsets for each input section and supplemental info block,
 588 // and set the final data size of the incremental output sections.
 589
 590 template<int size, bool big_endian>
 591 void
 592 Output_section_incremental_inputs<size, big_endian>::set_final_data_size()
 593 {
 594   const Incremental_inputs* inputs = this->inputs_;
 595   const unsigned int sizeof_addr = size / 8;
 596   const unsigned int rel_size = 8 + 2 * sizeof_addr;
 597
 598   // Offset of each input entry.
 599   unsigned int input_offset = this->header_size;
 600
 601   // Offset of each supplemental info block.
 602   unsigned int info_offset = this->header_size;
 603   info_offset += this->input_entry_size * inputs->input_file_count();
 604
 605   // Count each input file and its supplemental information block.
 606   for (Incremental_inputs::Input_list::const_iterator p =
 607            inputs->input_files().begin();
 608        p != inputs->input_files().end();
 609        ++p)
 610     {
 611       // Set the offset of the input file entry.
 612       (*p)->set_offset(input_offset);
 613       input_offset += this->input_entry_size;
 614
 615       // Set the offset of the supplemental info block.
 616       switch ((*p)->type())
 617         {
 618         case INCREMENTAL_INPUT_SCRIPT:
 619           // No supplemental info for a script.
 620           (*p)->set_info_offset(0);
 621           break;
 622         case INCREMENTAL_INPUT_OBJECT:
 623         case INCREMENTAL_INPUT_ARCHIVE_MEMBER:
 624           {
 625             Incremental_object_entry* entry = (*p)->object_entry();
 626             gold_assert(entry != NULL);
 627             (*p)->set_info_offset(info_offset);
 628             // Input section count + global symbol count.
 629             info_offset += 8;
 630             // Each input section.
 631             info_offset += (entry->get_input_section_count()
 632                             * (8 + 2 * sizeof_addr));
 633             // Each global symbol.
 634             const Object::Symbols* syms = entry->object()->get_global_symbols();
 635             info_offset += syms->size() * 16;
 636           }
 637           break;
 638         case INCREMENTAL_INPUT_SHARED_LIBRARY:
 639           {
 640             Incremental_object_entry* entry = (*p)->object_entry();
 641             gold_assert(entry != NULL);
 642             (*p)->set_info_offset(info_offset);
 643             // Global symbol count.
 644             info_offset += 4;
 645             // Each global symbol.
 646             const Object::Symbols* syms = entry->object()->get_global_symbols();
 647             unsigned int nsyms = syms != NULL ? syms->size() : 0;
 648             info_offset += nsyms * 4;
 649           }
 650           break;
 651         case INCREMENTAL_INPUT_ARCHIVE:
 652           {
 653             Incremental_archive_entry* entry = (*p)->archive_entry();
 654             gold_assert(entry != NULL);
 655             (*p)->set_info_offset(info_offset);
 656             // Member count + unused global symbol count.
 657             info_offset += 8;
 658             // Each member.
 659             info_offset += (entry->get_member_count() * 4);
 660             // Each global symbol.
 661             info_offset += (entry->get_unused_global_symbol_count() * 4);
 662           }
 663           break;
 664         default:
 665           gold_unreachable();
 666         }
 667     }
 668
 669   this->set_data_size(info_offset);
 670
 671   // Set the size of the .gnu_incremental_symtab section.
 672   inputs->symtab_section()->set_current_data_size(this->symtab_->output_count()
 673                                                   * sizeof(unsigned int));
 674
 675   // Set the size of the .gnu_incremental_relocs section.
 676   inputs->relocs_section()->set_current_data_size(inputs->get_reloc_count()
 677                                                   * rel_size);
 678
 679   // Set the size of the .gnu_incremental_got_plt section.
 680   Sized_target<size, big_endian>* target =
 681     parameters->sized_target<size, big_endian>();
 682   unsigned int got_count = target->got_entry_count();
 683   unsigned int plt_count = target->plt_entry_count();
 684   unsigned int got_plt_size = 8;  // GOT entry count, PLT entry count.
 685   got_plt_size = (got_plt_size + got_count + 3) & ~3;  // GOT type array.
 686   got_plt_size += got_count * 4 + plt_count * 4;  // GOT array, PLT array.
 687   inputs->got_plt_section()->set_current_data_size(got_plt_size);
 688 }
 689
 690 // Write the contents of the .gnu_incremental_inputs and
 691 // .gnu_incremental_symtab sections.
 692
 693 template<int size, bool big_endian>
 694 void
 695 Output_section_incremental_inputs<size, big_endian>::do_write(Output_file* of)
 696 {
 697   const Incremental_inputs* inputs = this->inputs_;
 698   Stringpool* strtab = inputs->get_stringpool();
 699
 700   // Get a view into the .gnu_incremental_inputs section.
 701   const off_t off = this->offset();
 702   const off_t oview_size = this->data_size();
 703   unsigned char* const oview = of->get_output_view(off, oview_size);
 704   unsigned char* pov = oview;
 705
 706   // Get a view into the .gnu_incremental_symtab section.
 707   const off_t symtab_off = inputs->symtab_section()->offset();
 708   const off_t symtab_size = inputs->symtab_section()->data_size();
 709   unsigned char* const symtab_view = of->get_output_view(symtab_off,
 710                                                          symtab_size);
 711
 712   // Allocate an array of linked list heads for the .gnu_incremental_symtab
 713   // section.  Each element corresponds to a global symbol in the output
 714   // symbol table, and points to the head of the linked list that threads
 715   // through the object file input entries.  The value of each element
 716   // is the section-relative offset to a global symbol entry in a
 717   // supplemental information block.
 718   unsigned int global_sym_count = this->symtab_->output_count();
 719   unsigned int* global_syms = new unsigned int[global_sym_count];
 720   memset(global_syms, 0, global_sym_count * sizeof(unsigned int));
 721
 722   // Write the section header.
 723   Stringpool::Key command_line_key = inputs->command_line_key();
 724   pov = this->write_header(pov, inputs->input_file_count(),
 725                            strtab->get_offset_from_key(command_line_key));
 726
 727   // Write the list of input files.
 728   pov = this->write_input_files(oview, pov, strtab);
 729
 730   // Write the supplemental information blocks for each input file.
 731   pov = this->write_info_blocks(oview, pov, strtab, global_syms,
 732                                 global_sym_count);
 733
 734   gold_assert(pov - oview == oview_size);
 735
 736   // Write the .gnu_incremental_symtab section.
 737   gold_assert(global_sym_count * 4 == symtab_size);
 738   this->write_symtab(symtab_view, global_syms, global_sym_count);
 739
 740   delete[] global_syms;
 741
 742   // Write the .gnu_incremental_got_plt section.
 743   const off_t got_plt_off = inputs->got_plt_section()->offset();
 744   const off_t got_plt_size = inputs->got_plt_section()->data_size();
 745   unsigned char* const got_plt_view = of->get_output_view(got_plt_off,
 746                                                           got_plt_size);
 747   this->write_got_plt(got_plt_view, got_plt_size);
 748
 749   of->write_output_view(off, oview_size, oview);
 750   of->write_output_view(symtab_off, symtab_size, symtab_view);
 751   of->write_output_view(got_plt_off, got_plt_size, got_plt_view);
 752 }
 753
 754 // Write the section header: version, input file count, offset of command line
 755 // in the string table, and 4 bytes of padding.
 756
 757 template<int size, bool big_endian>
 758 unsigned char*
 759 Output_section_incremental_inputs<size, big_endian>::write_header(
 760     unsigned char* pov,
 761     unsigned int input_file_count,
 762     section_offset_type command_line_offset)
 763 {
 764   Swap32::writeval(pov, INCREMENTAL_LINK_VERSION);
 765   Swap32::writeval(pov + 4, input_file_count);
 766   Swap32::writeval(pov + 8, command_line_offset);
 767   Swap32::writeval(pov + 12, 0);
 768   return pov + this->header_size;
 769 }
 770
 771 // Write the input file entries.
 772
 773 template<int size, bool big_endian>
 774 unsigned char*
 775 Output_section_incremental_inputs<size, big_endian>::write_input_files(
 776     unsigned char* oview,
 777     unsigned char* pov,
 778     Stringpool* strtab)
 779 {
 780   const Incremental_inputs* inputs = this->inputs_;
 781
 782   for (Incremental_inputs::Input_list::const_iterator p =
 783            inputs->input_files().begin();
 784        p != inputs->input_files().end();
 785        ++p)
 786     {
 787       gold_assert(static_cast<unsigned int>(pov - oview) == (*p)->get_offset());
 788       section_offset_type filename_offset =
 789           strtab->get_offset_from_key((*p)->get_filename_key());
 790       const Timespec& mtime = (*p)->get_mtime();
 791       Swap32::writeval(pov, filename_offset);
 792       Swap32::writeval(pov + 4, (*p)->get_info_offset());
 793       Swap64::writeval(pov + 8, mtime.seconds);
 794       Swap32::writeval(pov + 16, mtime.nanoseconds);
 795       Swap16::writeval(pov + 20, (*p)->type());
 796       Swap16::writeval(pov + 22, 0);
 797       pov += this->input_entry_size;
 798     }
 799   return pov;
 800 }
 801
 802 // Write the supplemental information blocks.
 803
 804 template<int size, bool big_endian>
 805 unsigned char*
 806 Output_section_incremental_inputs<size, big_endian>::write_info_blocks(
 807     unsigned char* oview,
 808     unsigned char* pov,
 809     Stringpool* strtab,
 810     unsigned int* global_syms,
 811     unsigned int global_sym_count)
 812 {
 813   const Incremental_inputs* inputs = this->inputs_;
 814   unsigned int first_global_index = this->symtab_->first_global_index();
 815
 816   for (Incremental_inputs::Input_list::const_iterator p =
 817            inputs->input_files().begin();
 818        p != inputs->input_files().end();
 819        ++p)
 820     {
 821       switch ((*p)->type())
 822         {
 823         case INCREMENTAL_INPUT_SCRIPT:
 824           // No supplemental info for a script.
 825           break;
 826
 827         case INCREMENTAL_INPUT_OBJECT:
 828         case INCREMENTAL_INPUT_ARCHIVE_MEMBER:
 829           {
 830             gold_assert(static_cast<unsigned int>(pov - oview)
 831                         == (*p)->get_info_offset());
 832             Incremental_object_entry* entry = (*p)->object_entry();
 833             gold_assert(entry != NULL);
 834             const Object* obj = entry->object();
 835             const Object::Symbols* syms = obj->get_global_symbols();
 836             // Write the input section count and global symbol count.
 837             unsigned int nsections = entry->get_input_section_count();
 838             unsigned int nsyms = syms->size();
 839             Swap32::writeval(pov, nsections);
 840             Swap32::writeval(pov + 4, nsyms);
 841             pov += 8;
 842
 843             // For each input section, write the name, output section index,
 844             // offset within output section, and input section size.
 845             for (unsigned int i = 0; i < nsections; i++)
 846               {
 847                 Stringpool::Key key = entry->get_input_section_name_key(i);
 848                 off_t name_offset = 0;
 849                 if (key != 0)
 850                   name_offset = strtab->get_offset_from_key(key);
 851                 int out_shndx = 0;
 852                 off_t out_offset = 0;
 853                 off_t sh_size = 0;
 854                 Output_section* os = obj->output_section(i);
 855                 if (os != NULL)
 856                   {
 857                     out_shndx = os->out_shndx();
 858                     out_offset = obj->output_section_offset(i);
 859                     sh_size = entry->get_input_section_size(i);
 860                   }
 861                 Swap32::writeval(pov, name_offset);
 862                 Swap32::writeval(pov + 4, out_shndx);
 863                 Swap::writeval(pov + 8, out_offset);
 864                 Swap::writeval(pov + 8 + sizeof_addr, sh_size);
 865                 pov += 8 + 2 * sizeof_addr;
 866               }
 867
 868             // For each global symbol, write its associated relocations,
 869             // add it to the linked list of globals, then write the
 870             // supplemental information:  global symbol table index,
 871             // linked list chain pointer, relocation count, and offset
 872             // to the relocations.
 873             for (unsigned int i = 0; i < nsyms; i++)
 874               {
 875                 const Symbol* sym = (*syms)[i];
 876                 if (sym->is_forwarder())
 877                   sym = this->symtab_->resolve_forwards(sym);
 878                 unsigned int symtab_index = sym->symtab_index();
 879                 unsigned int chain = 0;
 880                 unsigned int first_reloc = 0;
 881                 unsigned int nrelocs = obj->get_incremental_reloc_count(i);
 882                 if (nrelocs > 0)
 883                   {
 884                     gold_assert(symtab_index != -1U
 885                                 && (symtab_index - first_global_index
 886                                     < global_sym_count));
 887                     first_reloc = obj->get_incremental_reloc_base(i);
 888                     chain = global_syms[symtab_index - first_global_index];
 889                     global_syms[symtab_index - first_global_index] =
 890                         pov - oview;
 891                   }
 892                 Swap32::writeval(pov, symtab_index);
 893                 Swap32::writeval(pov + 4, chain);
 894                 Swap32::writeval(pov + 8, nrelocs);
 895                 Swap32::writeval(pov + 12, first_reloc * 3 * sizeof_addr);
 896                 pov += 16;
 897               }
 898           }
 899           break;
 900
 901         case INCREMENTAL_INPUT_SHARED_LIBRARY:
 902           {
 903             gold_assert(static_cast<unsigned int>(pov - oview)
 904                         == (*p)->get_info_offset());
 905             Incremental_object_entry* entry = (*p)->object_entry();
 906             gold_assert(entry != NULL);
 907             const Object* obj = entry->object();
 908             const Object::Symbols* syms = obj->get_global_symbols();
 909
 910             // Write the global symbol count.
 911             unsigned int nsyms = syms != NULL ? syms->size() : 0;
 912             Swap32::writeval(pov, nsyms);
 913             pov += 4;
 914
 915             // For each global symbol, write the global symbol table index.
 916             for (unsigned int i = 0; i < nsyms; i++)
 917               {
 918                 const Symbol* sym = (*syms)[i];
 919                 Swap32::writeval(pov, sym->symtab_index());
 920                 pov += 4;
 921               }
 922           }
 923           break;
 924
 925         case INCREMENTAL_INPUT_ARCHIVE:
 926           {
 927             gold_assert(static_cast<unsigned int>(pov - oview)
 928                         == (*p)->get_info_offset());
 929             Incremental_archive_entry* entry = (*p)->archive_entry();
 930             gold_assert(entry != NULL);
 931
 932             // Write the member count and unused global symbol count.
 933             unsigned int nmembers = entry->get_member_count();
 934             unsigned int nsyms = entry->get_unused_global_symbol_count();
 935             Swap32::writeval(pov, nmembers);
 936             Swap32::writeval(pov + 4, nsyms);
 937             pov += 8;
 938
 939             // For each member, write the offset to its input file entry.
 940             for (unsigned int i = 0; i < nmembers; ++i)
 941               {
 942                 Incremental_object_entry* member = entry->get_member(i);
 943                 Swap32::writeval(pov, member->get_offset());
 944                 pov += 4;
 945               }
 946
 947             // For each global symbol, write the name offset.
 948             for (unsigned int i = 0; i < nsyms; ++i)
 949               {
 950                 Stringpool::Key key = entry->get_unused_global_symbol(i);
 951                 Swap32::writeval(pov, strtab->get_offset_from_key(key));
 952                 pov += 4;
 953               }
 954           }
 955           break;
 956
 957         default:
 958           gold_unreachable();
 959         }
 960     }
 961   return pov;
 962 }
 963
 964 // Write the contents of the .gnu_incremental_symtab section.
 965
 966 template<int size, bool big_endian>
 967 void
 968 Output_section_incremental_inputs<size, big_endian>::write_symtab(
 969     unsigned char* pov,
 970     unsigned int* global_syms,
 971     unsigned int global_sym_count)
 972 {
 973   for (unsigned int i = 0; i < global_sym_count; ++i)
 974     {
 975       Swap32::writeval(pov, global_syms[i]);
 976       pov += 4;
 977     }
 978 }
 979
 980 // This struct holds the view information needed to write the
 981 // .gnu_incremental_got_plt section.
 982
 983 struct Got_plt_view_info
 984 {
 985   // Start of the GOT type array in the output view.
 986   unsigned char* got_type_p;
 987   // Start of the GOT descriptor array in the output view.
 988   unsigned char* got_desc_p;
 989   // Start of the PLT descriptor array in the output view.
 990   unsigned char* plt_desc_p;
 991   // Number of GOT entries.
 992   unsigned int got_count;
 993   // Number of PLT entries.
 994   unsigned int plt_count;
 995   // Offset of the first non-reserved PLT entry (this is a target-dependent value).
 996   unsigned int first_plt_entry_offset;
 997   // Size of a PLT entry (this is a target-dependent value).
 998   unsigned int plt_entry_size;
 999   // Value to write in the GOT descriptor array.  For global symbols,
1000   // this is the global symbol table index; for local symbols, it is
1001   // the offset of the input file entry in the .gnu_incremental_inputs
1002   // section.
1003   unsigned int got_descriptor;
1004 };
1005
1006 // Functor class for processing a GOT offset list for local symbols.
1007 // Writes the GOT type and symbol index into the GOT type and descriptor
1008 // arrays in the output section.
1009
1010 template<int size, bool big_endian>
1011 class Local_got_offset_visitor
1012 {
1013  public:
1014   Local_got_offset_visitor(struct Got_plt_view_info& info)
1015     : info_(info)
1016   { }
1017
1018   void
1019   operator()(unsigned int got_type, unsigned int got_offset)
1020   {
1021     unsigned int got_index = got_offset / this->got_entry_size_;
1022     gold_assert(got_index < this->info_.got_count);
1023     // We can only handle GOT entry types in the range 0..0x7e
1024     // because we use a byte array to store them, and we use the
1025     // high bit to flag a local symbol.
1026     gold_assert(got_type < 0x7f);
1027     this->info_.got_type_p[got_index] = got_type | 0x80;
1028     unsigned char* pov = this->info_.got_desc_p + got_index * 4;
1029     elfcpp::Swap<32, big_endian>::writeval(pov, this->info_.got_descriptor);
1030   }
1031
1032  private:
1033   static const unsigned int got_entry_size_ = size / 8;
1034   struct Got_plt_view_info& info_;
1035 };
1036
1037 // Functor class for processing a GOT offset list.  Writes the GOT type
1038 // and symbol index into the GOT type and descriptor arrays in the output
1039 // section.
1040
1041 template<int size, bool big_endian>
1042 class Global_got_offset_visitor
1043 {
1044  public:
1045   Global_got_offset_visitor(struct Got_plt_view_info& info)
1046     : info_(info)
1047   { }
1048
1049   void
1050   operator()(unsigned int got_type, unsigned int got_offset)
1051   {
1052     unsigned int got_index = got_offset / this->got_entry_size_;
1053     gold_assert(got_index < this->info_.got_count);
1054     // We can only handle GOT entry types in the range 0..0x7e
1055     // because we use a byte array to store them, and we use the
1056     // high bit to flag a local symbol.
1057     gold_assert(got_type < 0x7f);
1058     this->info_.got_type_p[got_index] = got_type;
1059     unsigned char* pov = this->info_.got_desc_p + got_index * 4;
1060     elfcpp::Swap<32, big_endian>::writeval(pov, this->info_.got_descriptor);
1061   }
1062
1063  private:
1064   static const unsigned int got_entry_size_ = size / 8;
1065   struct Got_plt_view_info& info_;
1066 };
1067
1068 // Functor class for processing the global symbol table.  Processes the
1069 // GOT offset list for the symbol, and writes the symbol table index
1070 // into the PLT descriptor array in the output section.
1071
1072 template<int size, bool big_endian>
1073 class Global_symbol_visitor_got_plt
1074 {
1075  public:
1076   Global_symbol_visitor_got_plt(struct Got_plt_view_info& info)
1077     : info_(info)
1078   { }
1079
1080   void
1081   operator()(const Sized_symbol<size>* sym)
1082   {
1083     typedef Global_got_offset_visitor<size, big_endian> Got_visitor;
1084     const Got_offset_list* got_offsets = sym->got_offset_list();
1085     if (got_offsets != NULL)
1086       {
1087         info_.got_descriptor = sym->symtab_index();
1088         got_offsets->for_all_got_offsets(Got_visitor(info_));
1089       }
1090     if (sym->has_plt_offset())
1091       {
1092         unsigned int plt_index =
1093             ((sym->plt_offset() - this->info_.first_plt_entry_offset)
1094              / this->info_.plt_entry_size);
1095         gold_assert(plt_index < this->info_.plt_count);
1096         unsigned char* pov = this->info_.plt_desc_p + plt_index * 4;
1097         elfcpp::Swap<32, big_endian>::writeval(pov, sym->symtab_index());
1098       }
1099   }
1100
1101  private:
1102   struct Got_plt_view_info& info_;
1103 };
1104
1105 // Write the contents of the .gnu_incremental_got_plt section.
1106
1107 template<int size, bool big_endian>
1108 void
1109 Output_section_incremental_inputs<size, big_endian>::write_got_plt(
1110     unsigned char* pov,
1111     off_t view_size)
1112 {
1113   Sized_target<size, big_endian>* target =
1114     parameters->sized_target<size, big_endian>();
1115
1116   // Set up the view information for the functors.
1117   struct Got_plt_view_info view_info;
1118   view_info.got_count = target->got_entry_count();
1119   view_info.plt_count = target->plt_entry_count();
1120   view_info.first_plt_entry_offset = target->first_plt_entry_offset();
1121   view_info.plt_entry_size = target->plt_entry_size();
1122   view_info.got_type_p = pov + 8;
1123   view_info.got_desc_p = (view_info.got_type_p
1124                           + ((view_info.got_count + 3) & ~3));
1125   view_info.plt_desc_p = view_info.got_desc_p + view_info.got_count * 4;
1126
1127   gold_assert(pov + view_size ==
1128               view_info.plt_desc_p + view_info.plt_count * 4);
1129
1130   // Write the section header.
1131   Swap32::writeval(pov, view_info.got_count);
1132   Swap32::writeval(pov + 4, view_info.plt_count);
1133
1134   // Initialize the GOT type array to 0xff (reserved).
1135   memset(view_info.got_type_p, 0xff, view_info.got_count);
1136
1137   // Write the incremental GOT descriptors for local symbols.
1138   for (Incremental_inputs::Input_list::const_iterator p =
1139            this->inputs_->input_files().begin();
1140        p != this->inputs_->input_files().end();
1141        ++p)
1142     {
1143       if ((*p)->type() != INCREMENTAL_INPUT_OBJECT
1144           && (*p)->type() != INCREMENTAL_INPUT_ARCHIVE_MEMBER)
1145         continue;
1146       Incremental_object_entry* entry = (*p)->object_entry();
1147       gold_assert(entry != NULL);
1148       const Sized_relobj<size, big_endian>* obj =
1149           static_cast<Sized_relobj<size, big_endian>*>(entry->object());
1150       gold_assert(obj != NULL);
1151       unsigned int nsyms = obj->local_symbol_count();
1152       for (unsigned int i = 0; i < nsyms; i++)
1153         {
1154           const Got_offset_list* got_offsets = obj->local_got_offset_list(i);
1155           if (got_offsets != NULL)
1156             {
1157               typedef Local_got_offset_visitor<size, big_endian> Got_visitor;
1158               view_info.got_descriptor = (*p)->get_offset();
1159               got_offsets->for_all_got_offsets(Got_visitor(view_info));
1160             }
1161         }
1162     }
1163
1164   // Write the incremental GOT and PLT descriptors for global symbols.
1165   typedef Global_symbol_visitor_got_plt<size, big_endian> Symbol_visitor;
1166   symtab_->for_all_symbols<size, Symbol_visitor>(Symbol_visitor(view_info));
1167 }
1168
1169 // Instantiate the templates we need.
1170
1171 #ifdef HAVE_TARGET_32_LITTLE
1172 template
1173 class Sized_incremental_binary<32, false>;
1174 #endif
1175
1176 #ifdef HAVE_TARGET_32_BIG
1177 template
1178 class Sized_incremental_binary<32, true>;
1179 #endif
1180
1181 #ifdef HAVE_TARGET_64_LITTLE
1182 template
1183 class Sized_incremental_binary<64, false>;
1184 #endif
1185
1186 #ifdef HAVE_TARGET_64_BIG
1187 template
1188 class Sized_incremental_binary<64, true>;
1189 #endif
1190
1191 } // End namespace gold.