gold/layout.h

   1 // layout.h -- lay out output file sections for gold  -*- C++ -*-
   2
   3 // Copyright 2006, 2007, 2008 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 #ifndef GOLD_LAYOUT_H
  24 #define GOLD_LAYOUT_H
  25
  26 #include <list>
  27 #include <string>
  28 #include <utility>
  29 #include <vector>
  30
  31 #include "script.h"
  32 #include "workqueue.h"
  33 #include "object.h"
  34 #include "dynobj.h"
  35 #include "stringpool.h"
  36
  37 namespace gold
  38 {
  39
  40 class General_options;
  41 class Input_objects;
  42 class Symbol_table;
  43 class Output_section_data;
  44 class Output_section;
  45 class Output_section_headers;
  46 class Output_segment;
  47 class Output_data;
  48 class Output_data_dynamic;
  49 class Output_symtab_xindex;
  50 class Eh_frame;
  51 class Target;
  52
  53 // This task function handles mapping the input sections to output
  54 // sections and laying them out in memory.
  55
  56 class Layout_task_runner : public Task_function_runner
  57 {
  58  public:
  59   // OPTIONS is the command line options, INPUT_OBJECTS is the list of
  60   // input objects, SYMTAB is the symbol table, LAYOUT is the layout
  61   // object.
  62   Layout_task_runner(const General_options& options,
  63                      const Input_objects* input_objects,
  64                      Symbol_table* symtab,
  65                      Target* target,
  66                      Layout* layout)
  67     : options_(options), input_objects_(input_objects), symtab_(symtab),
  68       target_(target), layout_(layout)
  69   { }
  70
  71   // Run the operation.
  72   void
  73   run(Workqueue*, const Task*);
  74
  75  private:
  76   Layout_task_runner(const Layout_task_runner&);
  77   Layout_task_runner& operator=(const Layout_task_runner&);
  78
  79   const General_options& options_;
  80   const Input_objects* input_objects_;
  81   Symbol_table* symtab_;
  82   Target* target_;
  83   Layout* layout_;
  84 };
  85
  86 // This class handles the details of laying out input sections.
  87
  88 class Layout
  89 {
  90  public:
  91   Layout(const General_options& options, Script_options*);
  92
  93   // Given an input section SHNDX, named NAME, with data in SHDR, from
  94   // the object file OBJECT, return the output section where this
  95   // input section should go.  RELOC_SHNDX is the index of a
  96   // relocation section which applies to this section, or 0 if none,
  97   // or -1U if more than one.  RELOC_TYPE is the type of the
  98   // relocation section if there is one.  Set *OFFSET to the offset
  99   // within the output section.
 100   template<int size, bool big_endian>
 101   Output_section*
 102   layout(Sized_relobj<size, big_endian> *object, unsigned int shndx,
 103          const char* name, const elfcpp::Shdr<size, big_endian>& shdr,
 104          unsigned int reloc_shndx, unsigned int reloc_type, off_t* offset);
 105
 106   // Layout an input reloc section when doing a relocatable link.  The
 107   // section is RELOC_SHNDX in OBJECT, with data in SHDR.
 108   // DATA_SECTION is the reloc section to which it refers.  RR is the
 109   // relocatable information.
 110   template<int size, bool big_endian>
 111   Output_section*
 112   layout_reloc(Sized_relobj<size, big_endian>* object,
 113                unsigned int reloc_shndx,
 114                const elfcpp::Shdr<size, big_endian>& shdr,
 115                Output_section* data_section,
 116                Relocatable_relocs* rr);
 117
 118   // Layout a group section when doing a relocatable link.
 119   template<int size, bool big_endian>
 120   void
 121   layout_group(Symbol_table* symtab,
 122                Sized_relobj<size, big_endian>* object,
 123                unsigned int group_shndx,
 124                const char* group_section_name,
 125                const char* signature,
 126                const elfcpp::Shdr<size, big_endian>& shdr,
 127                const elfcpp::Elf_Word* contents);
 128
 129   // Like layout, only for exception frame sections.  OBJECT is an
 130   // object file.  SYMBOLS is the contents of the symbol table
 131   // section, with size SYMBOLS_SIZE.  SYMBOL_NAMES is the contents of
 132   // the symbol name section, with size SYMBOL_NAMES_SIZE.  SHNDX is a
 133   // .eh_frame section in OBJECT.  SHDR is the section header.
 134   // RELOC_SHNDX is the index of a relocation section which applies to
 135   // this section, or 0 if none, or -1U if more than one.  RELOC_TYPE
 136   // is the type of the relocation section if there is one.  This
 137   // returns the output section, and sets *OFFSET to the offset.
 138   template<int size, bool big_endian>
 139   Output_section*
 140   layout_eh_frame(Sized_relobj<size, big_endian>* object,
 141                   const unsigned char* symbols,
 142                   off_t symbols_size,
 143                   const unsigned char* symbol_names,
 144                   off_t symbol_names_size,
 145                   unsigned int shndx,
 146                   const elfcpp::Shdr<size, big_endian>& shdr,
 147                   unsigned int reloc_shndx, unsigned int reloc_type,
 148                   off_t* offset);
 149
 150   // Handle a GNU stack note.  This is called once per input object
 151   // file.  SEEN_GNU_STACK is true if the object file has a
 152   // .note.GNU-stack section.  GNU_STACK_FLAGS is the section flags
 153   // from that section if there was one.
 154   void
 155   layout_gnu_stack(bool seen_gnu_stack, uint64_t gnu_stack_flags);
 156
 157   // Add an Output_section_data to the layout.  This is used for
 158   // special sections like the GOT section.
 159   void
 160   add_output_section_data(const char* name, elfcpp::Elf_Word type,
 161                           elfcpp::Elf_Xword flags,
 162                           Output_section_data*);
 163
 164   // Create dynamic sections if necessary.
 165   void
 166   create_initial_dynamic_sections(Symbol_table*);
 167
 168   // Define __start and __stop symbols for output sections.
 169   void
 170   define_section_symbols(Symbol_table*);
 171
 172   // Create sections for linker scripts.
 173   void
 174   create_script_sections()
 175   { this->script_options_->create_script_sections(this); }
 176
 177   // Define symbols from any linker script.
 178   void
 179   define_script_symbols(Symbol_table* symtab)
 180   { this->script_options_->add_symbols_to_table(symtab); }
 181
 182   // Define symbols for group signatures.
 183   void
 184   define_group_signatures(Symbol_table*);
 185
 186   // Return the Stringpool used for symbol names.
 187   const Stringpool*
 188   sympool() const
 189   { return &this->sympool_; }
 190
 191   // Return the Stringpool used for dynamic symbol names and dynamic
 192   // tags.
 193   const Stringpool*
 194   dynpool() const
 195   { return &this->dynpool_; }
 196
 197   // Return the symtab_xindex section used to hold large section
 198   // indexes for the normal symbol table.
 199   Output_symtab_xindex*
 200   symtab_xindex() const
 201   { return this->symtab_xindex_; }
 202
 203   // Return the dynsym_xindex section used to hold large section
 204   // indexes for the dynamic symbol table.
 205   Output_symtab_xindex*
 206   dynsym_xindex() const
 207   { return this->dynsym_xindex_; }
 208
 209   // Return whether a section is a .gnu.linkonce section, given the
 210   // section name.
 211   static inline bool
 212   is_linkonce(const char* name)
 213   { return strncmp(name, ".gnu.linkonce", sizeof(".gnu.linkonce") - 1) == 0; }
 214
 215   // Record the signature of a comdat section, and return whether to
 216   // include it in the link.  The GROUP parameter is true for a
 217   // section group signature, false for a signature derived from a
 218   // .gnu.linkonce section.
 219   bool
 220   add_comdat(const char*, bool group);
 221
 222   // Finalize the layout after all the input sections have been added.
 223   off_t
 224   finalize(const Input_objects*, Symbol_table*, Target*, const Task*);
 225
 226   // Return whether any sections require postprocessing.
 227   bool
 228   any_postprocessing_sections() const
 229   { return this->any_postprocessing_sections_; }
 230
 231   // Return the size of the output file.
 232   off_t
 233   output_file_size() const
 234   { return this->output_file_size_; }
 235
 236   // Return the TLS segment.  This will return NULL if there isn't
 237   // one.
 238   Output_segment*
 239   tls_segment() const
 240   { return this->tls_segment_; }
 241
 242   // Return the normal symbol table.
 243   Output_section*
 244   symtab_section() const
 245   {
 246     gold_assert(this->symtab_section_ != NULL);
 247     return this->symtab_section_;
 248   }
 249
 250   // Return the dynamic symbol table.
 251   Output_section*
 252   dynsym_section() const
 253   {
 254     gold_assert(this->dynsym_section_ != NULL);
 255     return this->dynsym_section_;
 256   }
 257
 258   // Return the dynamic tags.
 259   Output_data_dynamic*
 260   dynamic_data() const
 261   { return this->dynamic_data_; }
 262
 263   // Write out the output sections.
 264   void
 265   write_output_sections(Output_file* of) const;
 266
 267   // Write out data not associated with an input file or the symbol
 268   // table.
 269   void
 270   write_data(const Symbol_table*, Output_file*) const;
 271
 272   // Write out output sections which can not be written until all the
 273   // input sections are complete.
 274   void
 275   write_sections_after_input_sections(Output_file* of);
 276
 277   // Return an output section named NAME, or NULL if there is none.
 278   Output_section*
 279   find_output_section(const char* name) const;
 280
 281   // Return an output segment of type TYPE, with segment flags SET set
 282   // and segment flags CLEAR clear.  Return NULL if there is none.
 283   Output_segment*
 284   find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set,
 285                       elfcpp::Elf_Word clear) const;
 286
 287   // Return the number of segments we expect to produce.
 288   size_t
 289   expected_segment_count() const;
 290
 291   // Set a flag to indicate that an object file uses the static TLS model.
 292   void
 293   set_has_static_tls()
 294   { this->has_static_tls_ = true; }
 295
 296   // Return true if any object file uses the static TLS model.
 297   bool
 298   has_static_tls() const
 299   { return this->has_static_tls_; }
 300
 301   // Return the options which may be set by a linker script.
 302   Script_options*
 303   script_options()
 304   { return this->script_options_; }
 305
 306   const Script_options*
 307   script_options() const
 308   { return this->script_options_; }
 309
 310   // Compute and write out the build ID if needed.
 311   void
 312   write_build_id(Output_file*) const;
 313
 314   // Rewrite output file in binary format.
 315   void
 316   write_binary(Output_file* in) const;
 317
 318   // Dump statistical information to stderr.
 319   void
 320   print_stats() const;
 321
 322   // A list of segments.
 323
 324   typedef std::vector<Output_segment*> Segment_list;
 325
 326   // A list of sections.
 327
 328   typedef std::vector<Output_section*> Section_list;
 329
 330   // The list of information to write out which is not attached to
 331   // either a section or a segment.
 332   typedef std::vector<Output_data*> Data_list;
 333
 334   // Store the allocated sections into the section list.  This is used
 335   // by the linker script code.
 336   void
 337   get_allocated_sections(Section_list*) const;
 338
 339   // Make a section for a linker script to hold data.
 340   Output_section*
 341   make_output_section_for_script(const char* name);
 342
 343   // Make a segment.  This is used by the linker script code.
 344   Output_segment*
 345   make_output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags);
 346
 347   // Return the number of segments.
 348   size_t
 349   segment_count() const
 350   { return this->segment_list_.size(); }
 351
 352   // Map from section flags to segment flags.
 353   static elfcpp::Elf_Word
 354   section_flags_to_segment(elfcpp::Elf_Xword flags);
 355
 356   // Attach sections to segments.
 357   void
 358   attach_sections_to_segments();
 359
 360  private:
 361   Layout(const Layout&);
 362   Layout& operator=(const Layout&);
 363
 364   // Mapping from .gnu.linkonce section names to output section names.
 365   struct Linkonce_mapping
 366   {
 367     const char* from;
 368     int fromlen;
 369     const char* to;
 370     int tolen;
 371   };
 372   static const Linkonce_mapping linkonce_mapping[];
 373   static const int linkonce_mapping_count;
 374
 375   // During a relocatable link, a list of group sections and
 376   // signatures.
 377   struct Group_signature
 378   {
 379     // The group section.
 380     Output_section* section;
 381     // The signature.
 382     const char* signature;
 383
 384     Group_signature()
 385       : section(NULL), signature(NULL)
 386     { }
 387
 388     Group_signature(Output_section* sectiona, const char* signaturea)
 389       : section(sectiona), signature(signaturea)
 390     { }
 391   };
 392   typedef std::vector<Group_signature> Group_signatures;
 393
 394   // Create a .note section, filling in the header.
 395   Output_section*
 396   create_note(const char* name, int note_type, size_t descsz,
 397               bool allocate, size_t* trailing_padding);
 398
 399   // Create a .note section for gold.
 400   void
 401   create_gold_note();
 402
 403   // Record whether the stack must be executable.
 404   void
 405   create_executable_stack_info(const Target*);
 406
 407   // Create a build ID note if needed.
 408   void
 409   create_build_id();
 410
 411   // Find the first read-only PT_LOAD segment, creating one if
 412   // necessary.
 413   Output_segment*
 414   find_first_load_seg();
 415
 416   // Count the local symbols in the regular symbol table and the dynamic
 417   // symbol table, and build the respective string pools.
 418   void
 419   count_local_symbols(const Task*, const Input_objects*);
 420
 421   // Create the output sections for the symbol table.
 422   void
 423   create_symtab_sections(const Input_objects*, Symbol_table*,
 424                          unsigned int, off_t*);
 425
 426   // Create the .shstrtab section.
 427   Output_section*
 428   create_shstrtab();
 429
 430   // Create the section header table.
 431   void
 432   create_shdrs(const Output_section* shstrtab_section, off_t*);
 433
 434   // Create the dynamic symbol table.
 435   void
 436   create_dynamic_symtab(const Input_objects*, Symbol_table*,
 437                         Output_section** pdynstr,
 438                         unsigned int* plocal_dynamic_count,
 439                         std::vector<Symbol*>* pdynamic_symbols,
 440                         Versions* versions);
 441
 442   // Assign offsets to each local portion of the dynamic symbol table.
 443   void
 444   assign_local_dynsym_offsets(const Input_objects*);
 445
 446   // Finish the .dynamic section and PT_DYNAMIC segment.
 447   void
 448   finish_dynamic_section(const Input_objects*, const Symbol_table*);
 449
 450   // Create the .interp section and PT_INTERP segment.
 451   void
 452   create_interp(const Target* target);
 453
 454   // Create the version sections.
 455   void
 456   create_version_sections(const Versions*,
 457                           const Symbol_table*,
 458                           unsigned int local_symcount,
 459                           const std::vector<Symbol*>& dynamic_symbols,
 460                           const Output_section* dynstr);
 461
 462   template<int size, bool big_endian>
 463   void
 464   sized_create_version_sections(const Versions* versions,
 465                                 const Symbol_table*,
 466                                 unsigned int local_symcount,
 467                                 const std::vector<Symbol*>& dynamic_symbols,
 468                                 const Output_section* dynstr);
 469
 470   // Return whether to include this section in the link.
 471   template<int size, bool big_endian>
 472   bool
 473   include_section(Sized_relobj<size, big_endian>* object, const char* name,
 474                   const elfcpp::Shdr<size, big_endian>&);
 475
 476   // Return the output section name to use given an input section
 477   // name.  Set *PLEN to the length of the name.  *PLEN must be
 478   // initialized to the length of NAME.
 479   static const char*
 480   output_section_name(const char* name, size_t* plen);
 481
 482   // Return the output section name to use for a linkonce section
 483   // name.  PLEN is as for output_section_name.
 484   static const char*
 485   linkonce_output_name(const char* name, size_t* plen);
 486
 487   // Return the number of allocated output sections.
 488   size_t
 489   allocated_output_section_count() const;
 490
 491   // Return the output section for NAME, TYPE and FLAGS.
 492   Output_section*
 493   get_output_section(const char* name, Stringpool::Key name_key,
 494                      elfcpp::Elf_Word type, elfcpp::Elf_Xword flags);
 495
 496   // Choose the output section for NAME in RELOBJ.
 497   Output_section*
 498   choose_output_section(const Relobj* relobj, const char* name,
 499                         elfcpp::Elf_Word type, elfcpp::Elf_Xword flags,
 500                         bool is_input_section);
 501
 502   // Create a new Output_section.
 503   Output_section*
 504   make_output_section(const char* name, elfcpp::Elf_Word type,
 505                       elfcpp::Elf_Xword flags);
 506
 507   // Attach a section to a segment.
 508   void
 509   attach_section_to_segment(Output_section*);
 510
 511   // Attach an allocated section to a segment.
 512   void
 513   attach_allocated_section_to_segment(Output_section*);
 514
 515   // Set the final file offsets of all the segments.
 516   off_t
 517   set_segment_offsets(const Target*, Output_segment*, unsigned int* pshndx);
 518
 519   // Set the file offsets of the sections when doing a relocatable
 520   // link.
 521   off_t
 522   set_relocatable_section_offsets(Output_data*, unsigned int* pshndx);
 523
 524   // Set the final file offsets of all the sections not associated
 525   // with a segment.  We set section offsets in three passes: the
 526   // first handles all allocated sections, the second sections that
 527   // require postprocessing, and the last the late-bound STRTAB
 528   // sections (probably only shstrtab, which is the one we care about
 529   // because it holds section names).
 530   enum Section_offset_pass
 531   {
 532     BEFORE_INPUT_SECTIONS_PASS,
 533     POSTPROCESSING_SECTIONS_PASS,
 534     STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
 535   };
 536   off_t
 537   set_section_offsets(off_t, Section_offset_pass pass);
 538
 539   // Set the final section indexes of all the sections not associated
 540   // with a segment.  Returns the next unused index.
 541   unsigned int
 542   set_section_indexes(unsigned int pshndx);
 543
 544   // Set the section addresses when using a script.
 545   Output_segment*
 546   set_section_addresses_from_script(Symbol_table*);
 547
 548   // Return whether SEG1 comes before SEG2 in the output file.
 549   static bool
 550   segment_precedes(const Output_segment* seg1, const Output_segment* seg2);
 551
 552   // A mapping used for group signatures.
 553   typedef Unordered_map<std::string, bool> Signatures;
 554
 555   // Mapping from input section name/type/flags to output section.  We
 556   // use canonicalized strings here.
 557
 558   typedef std::pair<Stringpool::Key,
 559                     std::pair<elfcpp::Elf_Word, elfcpp::Elf_Xword> > Key;
 560
 561   struct Hash_key
 562   {
 563     size_t
 564     operator()(const Key& k) const;
 565   };
 566
 567   typedef Unordered_map<Key, Output_section*, Hash_key> Section_name_map;
 568
 569   // A comparison class for segments.
 570
 571   struct Compare_segments
 572   {
 573     bool
 574     operator()(const Output_segment* seg1, const Output_segment* seg2)
 575     { return Layout::segment_precedes(seg1, seg2); }
 576   };
 577
 578   // A reference to the options on the command line.
 579   const General_options& options_;
 580   // Information set by scripts or by command line options.
 581   Script_options* script_options_;
 582   // The output section names.
 583   Stringpool namepool_;
 584   // The output symbol names.
 585   Stringpool sympool_;
 586   // The dynamic strings, if needed.
 587   Stringpool dynpool_;
 588   // The list of group sections and linkonce sections which we have seen.
 589   Signatures signatures_;
 590   // The mapping from input section name/type/flags to output sections.
 591   Section_name_map section_name_map_;
 592   // The list of output segments.
 593   Segment_list segment_list_;
 594   // The list of output sections.
 595   Section_list section_list_;
 596   // The list of output sections which are not attached to any output
 597   // segment.
 598   Section_list unattached_section_list_;
 599   // Whether we have attached the sections to the segments.
 600   bool sections_are_attached_;
 601   // The list of unattached Output_data objects which require special
 602   // handling because they are not Output_sections.
 603   Data_list special_output_list_;
 604   // The section headers.
 605   Output_section_headers* section_headers_;
 606   // A pointer to the PT_TLS segment if there is one.
 607   Output_segment* tls_segment_;
 608   // The SHT_SYMTAB output section.
 609   Output_section* symtab_section_;
 610   // The SHT_SYMTAB_SHNDX for the regular symbol table if there is one.
 611   Output_symtab_xindex* symtab_xindex_;
 612   // The SHT_DYNSYM output section if there is one.
 613   Output_section* dynsym_section_;
 614   // The SHT_SYMTAB_SHNDX for the dynamic symbol table if there is one.
 615   Output_symtab_xindex* dynsym_xindex_;
 616   // The SHT_DYNAMIC output section if there is one.
 617   Output_section* dynamic_section_;
 618   // The dynamic data which goes into dynamic_section_.
 619   Output_data_dynamic* dynamic_data_;
 620   // The exception frame output section if there is one.
 621   Output_section* eh_frame_section_;
 622   // The exception frame data for eh_frame_section_.
 623   Eh_frame* eh_frame_data_;
 624   // Whether we have added eh_frame_data_ to the .eh_frame section.
 625   bool added_eh_frame_data_;
 626   // The exception frame header output section if there is one.
 627   Output_section* eh_frame_hdr_section_;
 628   // The space for the build ID checksum if there is one.
 629   Output_section_data* build_id_note_;
 630   // A list of group sections and their signatures.
 631   Group_signatures group_signatures_;
 632   // The size of the output file.
 633   off_t output_file_size_;
 634   // Whether we have seen an object file marked to require an
 635   // executable stack.
 636   bool input_requires_executable_stack_;
 637   // Whether we have seen at least one object file with an executable
 638   // stack marker.
 639   bool input_with_gnu_stack_note_;
 640   // Whether we have seen at least one object file without an
 641   // executable stack marker.
 642   bool input_without_gnu_stack_note_;
 643   // Whether we have seen an object file that uses the static TLS model.
 644   bool has_static_tls_;
 645   // Whether any sections require postprocessing.
 646   bool any_postprocessing_sections_;
 647 };
 648
 649 // This task handles writing out data in output sections which is not
 650 // part of an input section, or which requires special handling.  When
 651 // this is done, it unblocks both output_sections_blocker and
 652 // final_blocker.
 653
 654 class Write_sections_task : public Task
 655 {
 656  public:
 657   Write_sections_task(const Layout* layout, Output_file* of,
 658                       Task_token* output_sections_blocker,
 659                       Task_token* final_blocker)
 660     : layout_(layout), of_(of),
 661       output_sections_blocker_(output_sections_blocker),
 662       final_blocker_(final_blocker)
 663   { }
 664
 665   // The standard Task methods.
 666
 667   Task_token*
 668   is_runnable();
 669
 670   void
 671   locks(Task_locker*);
 672
 673   void
 674   run(Workqueue*);
 675
 676   std::string
 677   get_name() const
 678   { return "Write_sections_task"; }
 679
 680  private:
 681   class Write_sections_locker;
 682
 683   const Layout* layout_;
 684   Output_file* of_;
 685   Task_token* output_sections_blocker_;
 686   Task_token* final_blocker_;
 687 };
 688
 689 // This task handles writing out data which is not part of a section
 690 // or segment.
 691
 692 class Write_data_task : public Task
 693 {
 694  public:
 695   Write_data_task(const Layout* layout, const Symbol_table* symtab,
 696                   Output_file* of, Task_token* final_blocker)
 697     : layout_(layout), symtab_(symtab), of_(of), final_blocker_(final_blocker)
 698   { }
 699
 700   // The standard Task methods.
 701
 702   Task_token*
 703   is_runnable();
 704
 705   void
 706   locks(Task_locker*);
 707
 708   void
 709   run(Workqueue*);
 710
 711   std::string
 712   get_name() const
 713   { return "Write_data_task"; }
 714
 715  private:
 716   const Layout* layout_;
 717   const Symbol_table* symtab_;
 718   Output_file* of_;
 719   Task_token* final_blocker_;
 720 };
 721
 722 // This task handles writing out the global symbols.
 723
 724 class Write_symbols_task : public Task
 725 {
 726  public:
 727   Write_symbols_task(const Layout* layout, const Symbol_table* symtab,
 728                      const Input_objects* input_objects,
 729                      const Stringpool* sympool, const Stringpool* dynpool,
 730                      Output_file* of, Task_token* final_blocker)
 731     : layout_(layout), symtab_(symtab), input_objects_(input_objects),
 732       sympool_(sympool), dynpool_(dynpool), of_(of),
 733       final_blocker_(final_blocker)
 734   { }
 735
 736   // The standard Task methods.
 737
 738   Task_token*
 739   is_runnable();
 740
 741   void
 742   locks(Task_locker*);
 743
 744   void
 745   run(Workqueue*);
 746
 747   std::string
 748   get_name() const
 749   { return "Write_symbols_task"; }
 750
 751  private:
 752   const Layout* layout_;
 753   const Symbol_table* symtab_;
 754   const Input_objects* input_objects_;
 755   const Stringpool* sympool_;
 756   const Stringpool* dynpool_;
 757   Output_file* of_;
 758   Task_token* final_blocker_;
 759 };
 760
 761 // This task handles writing out data in output sections which can't
 762 // be written out until all the input sections have been handled.
 763 // This is for sections whose contents is based on the contents of
 764 // other output sections.
 765
 766 class Write_after_input_sections_task : public Task
 767 {
 768  public:
 769   Write_after_input_sections_task(Layout* layout, Output_file* of,
 770                                   Task_token* input_sections_blocker,
 771                                   Task_token* final_blocker)
 772     : layout_(layout), of_(of),
 773       input_sections_blocker_(input_sections_blocker),
 774       final_blocker_(final_blocker)
 775   { }
 776
 777   // The standard Task methods.
 778
 779   Task_token*
 780   is_runnable();
 781
 782   void
 783   locks(Task_locker*);
 784
 785   void
 786   run(Workqueue*);
 787
 788   std::string
 789   get_name() const
 790   { return "Write_after_input_sections_task"; }
 791
 792  private:
 793   Layout* layout_;
 794   Output_file* of_;
 795   Task_token* input_sections_blocker_;
 796   Task_token* final_blocker_;
 797 };
 798
 799 // This task function handles closing the file.
 800
 801 class Close_task_runner : public Task_function_runner
 802 {
 803  public:
 804   Close_task_runner(const General_options* options, const Layout* layout,
 805                     Output_file* of)
 806     : options_(options), layout_(layout), of_(of)
 807   { }
 808
 809   // Run the operation.
 810   void
 811   run(Workqueue*, const Task*);
 812
 813  private:
 814   const General_options* options_;
 815   const Layout* layout_;
 816   Output_file* of_;
 817 };
 818
 819 // A small helper function to align an address.
 820
 821 inline uint64_t
 822 align_address(uint64_t address, uint64_t addralign)
 823 {
 824   if (addralign != 0)
 825     address = (address + addralign - 1) &~ (addralign - 1);
 826   return address;
 827 }
 828
 829 } // End namespace gold.
 830
 831 #endif // !defined(GOLD_LAYOUT_H)