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