gold/symtab.h

   1 // symtab.h -- the gold symbol table   -*- C++ -*-
   2
   3 // Symbol_table
   4 //   The symbol table.
   5
   6 #include <string>
   7 #include <utility>
   8 #include <vector>
   9
  10 #include "elfcpp.h"
  11 #include "stringpool.h"
  12 #include "object.h"
  13
  14 #ifndef GOLD_SYMTAB_H
  15 #define GOLD_SYMTAB_H
  16
  17 namespace gold
  18 {
  19
  20 class Object;
  21 class Relobj;
  22 template<int size, bool big_endian>
  23 class Sized_relobj;
  24 class Dynobj;
  25 template<int size, bool big_endian>
  26 class Sized_dynobj;
  27 class Versions;
  28 class Output_data;
  29 class Output_section;
  30 class Output_segment;
  31 class Output_file;
  32 class Target;
  33
  34 // The base class of an entry in the symbol table.  The symbol table
  35 // can have a lot of entries, so we don't want this class to big.
  36 // Size dependent fields can be found in the template class
  37 // Sized_symbol.  Targets may support their own derived classes.
  38
  39 class Symbol
  40 {
  41  public:
  42   // Because we want the class to be small, we don't use any virtual
  43   // functions.  But because symbols can be defined in different
  44   // places, we need to classify them.  This enum is the different
  45   // sources of symbols we support.
  46   enum Source
  47   {
  48     // Symbol defined in a relocatable or dynamic input file--this is
  49     // the most common case.
  50     FROM_OBJECT,
  51     // Symbol defined in an Output_data, a special section created by
  52     // the target.
  53     IN_OUTPUT_DATA,
  54     // Symbol defined in an Output_segment, with no associated
  55     // section.
  56     IN_OUTPUT_SEGMENT,
  57     // Symbol value is constant.
  58     CONSTANT
  59   };
  60
  61   // When the source is IN_OUTPUT_SEGMENT, we need to describe what
  62   // the offset means.
  63   enum Segment_offset_base
  64   {
  65     // From the start of the segment.
  66     SEGMENT_START,
  67     // From the end of the segment.
  68     SEGMENT_END,
  69     // From the filesz of the segment--i.e., after the loaded bytes
  70     // but before the bytes which are allocated but zeroed.
  71     SEGMENT_BSS
  72   };
  73
  74   // Return the symbol name.
  75   const char*
  76   name() const
  77   { return this->name_; }
  78
  79   // Return the symbol version.  This will return NULL for an
  80   // unversioned symbol.
  81   const char*
  82   version() const
  83   { return this->version_; }
  84
  85   // Return the symbol source.
  86   Source
  87   source() const
  88   { return this->source_; }
  89
  90   // Return the object with which this symbol is associated.
  91   Object*
  92   object() const
  93   {
  94     gold_assert(this->source_ == FROM_OBJECT);
  95     return this->u_.from_object.object;
  96   }
  97
  98   // Return the index of the section in the input relocatable or
  99   // dynamic object file.
 100   unsigned int
 101   shndx() const
 102   {
 103     gold_assert(this->source_ == FROM_OBJECT);
 104     return this->u_.from_object.shndx;
 105   }
 106
 107   // Return the output data section with which this symbol is
 108   // associated, if the symbol was specially defined with respect to
 109   // an output data section.
 110   Output_data*
 111   output_data() const
 112   {
 113     gold_assert(this->source_ == IN_OUTPUT_DATA);
 114     return this->u_.in_output_data.output_data;
 115   }
 116
 117   // If this symbol was defined with respect to an output data
 118   // section, return whether the value is an offset from end.
 119   bool
 120   offset_is_from_end() const
 121   {
 122     gold_assert(this->source_ == IN_OUTPUT_DATA);
 123     return this->u_.in_output_data.offset_is_from_end;
 124   }
 125
 126   // Return the output segment with which this symbol is associated,
 127   // if the symbol was specially defined with respect to an output
 128   // segment.
 129   Output_segment*
 130   output_segment() const
 131   {
 132     gold_assert(this->source_ == IN_OUTPUT_SEGMENT);
 133     return this->u_.in_output_segment.output_segment;
 134   }
 135
 136   // If this symbol was defined with respect to an output segment,
 137   // return the offset base.
 138   Segment_offset_base
 139   offset_base() const
 140   {
 141     gold_assert(this->source_ == IN_OUTPUT_SEGMENT);
 142     return this->u_.in_output_segment.offset_base;
 143   }
 144
 145   // Return the symbol binding.
 146   elfcpp::STB
 147   binding() const
 148   { return this->binding_; }
 149
 150   // Return the symbol type.
 151   elfcpp::STT
 152   type() const
 153   { return this->type_; }
 154
 155   // Return the symbol visibility.
 156   elfcpp::STV
 157   visibility() const
 158   { return this->visibility_; }
 159
 160   // Return the non-visibility part of the st_other field.
 161   unsigned char
 162   nonvis() const
 163   { return this->nonvis_; }
 164
 165   // Return whether this symbol is a forwarder.  This will never be
 166   // true of a symbol found in the hash table, but may be true of
 167   // symbol pointers attached to object files.
 168   bool
 169   is_forwarder() const
 170   { return this->is_forwarder_; }
 171
 172   // Mark this symbol as a forwarder.
 173   void
 174   set_forwarder()
 175   { this->is_forwarder_ = true; }
 176
 177   // Return whether this symbol needs an entry in the dynamic symbol
 178   // table.
 179   bool
 180   needs_dynsym_entry() const
 181   { return this->needs_dynsym_entry_; }
 182
 183   // Mark this symbol as needing an entry in the dynamic symbol table.
 184   void
 185   set_needs_dynsym_entry()
 186   { this->needs_dynsym_entry_ = true; }
 187
 188   // Mark this symbol as having been seen in a dynamic object.
 189   void
 190   set_in_dyn()
 191   { this->in_dyn_ = true; }
 192
 193   // Return the index of this symbol in the output file symbol table.
 194   // A value of -1U means that this symbol is not going into the
 195   // output file.  This starts out as zero, and is set to a non-zero
 196   // value by Symbol_table::finalize.  It is an error to ask for the
 197   // symbol table index before it has been set.
 198   unsigned int
 199   symtab_index() const
 200   {
 201     gold_assert(this->symtab_index_ != 0);
 202     return this->symtab_index_;
 203   }
 204
 205   // Set the index of the symbol in the output file symbol table.
 206   void
 207   set_symtab_index(unsigned int index)
 208   {
 209     gold_assert(index != 0);
 210     this->symtab_index_ = index;
 211   }
 212
 213   // Return whether this symbol already has an index in the output
 214   // file symbol table.
 215   bool
 216   has_symtab_index() const
 217   { return this->symtab_index_ != 0; }
 218
 219   // Return the index of this symbol in the dynamic symbol table.  A
 220   // value of -1U means that this symbol is not going into the dynamic
 221   // symbol table.  This starts out as zero, and is set to a non-zero
 222   // during Layout::finalize.  It is an error to ask for the dynamic
 223   // symbol table index before it has been set.
 224   unsigned int
 225   dynsym_index() const
 226   {
 227     gold_assert(this->dynsym_index_ != 0);
 228     return this->dynsym_index_;
 229   }
 230
 231   // Set the index of the symbol in the dynamic symbol table.
 232   void
 233   set_dynsym_index(unsigned int index)
 234   {
 235     gold_assert(index != 0);
 236     this->dynsym_index_ = index;
 237   }
 238
 239   // Return whether this symbol already has an index in the dynamic
 240   // symbol table.
 241   bool
 242   has_dynsym_index() const
 243   { return this->dynsym_index_ != 0; }
 244
 245   // Return whether this symbol has an entry in the GOT section.
 246   bool
 247   has_got_offset() const
 248   { return this->has_got_offset_; }
 249
 250   // Return the offset into the GOT section of this symbol.
 251   unsigned int
 252   got_offset() const
 253   {
 254     gold_assert(this->has_got_offset());
 255     return this->got_offset_;
 256   }
 257
 258   // Set the GOT offset of this symbol.
 259   void
 260   set_got_offset(unsigned int got_offset)
 261   {
 262     this->has_got_offset_ = true;
 263     this->got_offset_ = got_offset;
 264   }
 265
 266   // Return whether this symbol has an entry in the PLT section.
 267   bool
 268   has_plt_offset() const
 269   { return this->has_plt_offset_; }
 270
 271   // Return the offset into the PLT section of this symbol.
 272   unsigned int
 273   plt_offset() const
 274   {
 275     gold_assert(this->has_plt_offset());
 276     return this->plt_offset_;
 277   }
 278
 279   // Set the PLT offset of this symbol.
 280   void
 281   set_plt_offset(unsigned int plt_offset)
 282   {
 283     this->has_plt_offset_ = true;
 284     this->plt_offset_ = plt_offset;
 285   }
 286
 287   // Return true if the final value of this symbol is known at link
 288   // time.
 289   bool
 290   final_value_is_known(const General_options* options) const
 291   {
 292     if (options->is_shared())
 293       return false;
 294     return this->source_ != FROM_OBJECT || !this->object()->is_dynamic();
 295   }
 296
 297   // Return whether this is a defined symbol (not undefined or
 298   // common).
 299   bool
 300   is_defined() const
 301   {
 302     return (this->source_ != FROM_OBJECT
 303             || (this->shndx() != elfcpp::SHN_UNDEF
 304                 && this->shndx() != elfcpp::SHN_COMMON));
 305   }
 306
 307   // Return true if this symbol is from a dynamic object.
 308   bool
 309   is_from_dynobj() const
 310   {
 311     return this->source_ == FROM_OBJECT && this->object()->is_dynamic();
 312   }
 313
 314   // Return whether this is an undefined symbol.
 315   bool
 316   is_undefined() const
 317   {
 318     return this->source_ == FROM_OBJECT && this->shndx() == elfcpp::SHN_UNDEF;
 319   }
 320
 321   // Return whether this is a common symbol.
 322   bool
 323   is_common() const
 324   {
 325     return (this->source_ == FROM_OBJECT
 326             && (this->shndx() == elfcpp::SHN_COMMON
 327                 || this->type_ == elfcpp::STT_COMMON));
 328   }
 329
 330   // Return whether there should be a warning for references to this
 331   // symbol.
 332   bool
 333   has_warning() const
 334   { return this->has_warning_; }
 335
 336   // Mark this symbol as having a warning.
 337   void
 338   set_has_warning()
 339   { this->has_warning_ = true; }
 340
 341  protected:
 342   // Instances of this class should always be created at a specific
 343   // size.
 344   Symbol()
 345   { memset(this, 0, sizeof *this); }
 346
 347   // Initialize the general fields.
 348   void
 349   init_fields(const char* name, const char* version,
 350               elfcpp::STT type, elfcpp::STB binding,
 351               elfcpp::STV visibility, unsigned char nonvis);
 352
 353   // Initialize fields from an ELF symbol in OBJECT.
 354   template<int size, bool big_endian>
 355   void
 356   init_base(const char *name, const char* version, Object* object,
 357             const elfcpp::Sym<size, big_endian>&);
 358
 359   // Initialize fields for an Output_data.
 360   void
 361   init_base(const char* name, Output_data*, elfcpp::STT, elfcpp::STB,
 362             elfcpp::STV, unsigned char nonvis, bool offset_is_from_end);
 363
 364   // Initialize fields for an Output_segment.
 365   void
 366   init_base(const char* name, Output_segment* os, elfcpp::STT type,
 367             elfcpp::STB binding, elfcpp::STV visibility,
 368             unsigned char nonvis, Segment_offset_base offset_base);
 369
 370   // Initialize fields for a constant.
 371   void
 372   init_base(const char* name, elfcpp::STT type, elfcpp::STB binding,
 373             elfcpp::STV visibility, unsigned char nonvis);
 374
 375   // Override existing symbol.
 376   template<int size, bool big_endian>
 377   void
 378   override_base(const elfcpp::Sym<size, big_endian>&, Object* object,
 379                 const char* version);
 380
 381  private:
 382   Symbol(const Symbol&);
 383   Symbol& operator=(const Symbol&);
 384
 385   // Symbol name (expected to point into a Stringpool).
 386   const char* name_;
 387   // Symbol version (expected to point into a Stringpool).  This may
 388   // be NULL.
 389   const char* version_;
 390
 391   union
 392   {
 393     // This struct is used if SOURCE_ == FROM_OBJECT.
 394     struct
 395     {
 396       // Object in which symbol is defined, or in which it was first
 397       // seen.
 398       Object* object;
 399       // Section number in object_ in which symbol is defined.
 400       unsigned int shndx;
 401     } from_object;
 402
 403     // This struct is used if SOURCE_ == IN_OUTPUT_DATA.
 404     struct
 405     {
 406       // Output_data in which symbol is defined.  Before
 407       // Layout::finalize the symbol's value is an offset within the
 408       // Output_data.
 409       Output_data* output_data;
 410       // True if the offset is from the end, false if the offset is
 411       // from the beginning.
 412       bool offset_is_from_end;
 413     } in_output_data;
 414
 415     // This struct is used if SOURCE_ == IN_OUTPUT_SEGMENT.
 416     struct
 417     {
 418       // Output_segment in which the symbol is defined.  Before
 419       // Layout::finalize the symbol's value is an offset.
 420       Output_segment* output_segment;
 421       // The base to use for the offset before Layout::finalize.
 422       Segment_offset_base offset_base;
 423     } in_output_segment;
 424   } u_;
 425
 426   // The index of this symbol in the output file.  If the symbol is
 427   // not going into the output file, this value is -1U.  This field
 428   // starts as always holding zero.  It is set to a non-zero value by
 429   // Symbol_table::finalize.
 430   unsigned int symtab_index_;
 431
 432   // The index of this symbol in the dynamic symbol table.  If the
 433   // symbol is not going into the dynamic symbol table, this value is
 434   // -1U.  This field starts as always holding zero.  It is set to a
 435   // non-zero value during Layout::finalize.
 436   unsigned int dynsym_index_;
 437
 438   // If this symbol has an entry in the GOT section (has_got_offset_
 439   // is true), this is the offset from the start of the GOT section.
 440   unsigned int got_offset_;
 441
 442   // If this symbol has an entry in the PLT section (has_plt_offset_
 443   // is true), then this is the offset from the start of the PLT
 444   // section.
 445   unsigned int plt_offset_;
 446
 447   // Symbol type.
 448   elfcpp::STT type_ : 4;
 449   // Symbol binding.
 450   elfcpp::STB binding_ : 4;
 451   // Symbol visibility.
 452   elfcpp::STV visibility_ : 2;
 453   // Rest of symbol st_other field.
 454   unsigned int nonvis_ : 6;
 455   // The type of symbol.
 456   Source source_ : 3;
 457   // True if this symbol always requires special target-specific
 458   // handling.
 459   bool is_target_special_ : 1;
 460   // True if this is the default version of the symbol.
 461   bool is_def_ : 1;
 462   // True if this symbol really forwards to another symbol.  This is
 463   // used when we discover after the fact that two different entries
 464   // in the hash table really refer to the same symbol.  This will
 465   // never be set for a symbol found in the hash table, but may be set
 466   // for a symbol found in the list of symbols attached to an Object.
 467   // It forwards to the symbol found in the forwarders_ map of
 468   // Symbol_table.
 469   bool is_forwarder_ : 1;
 470   // True if this symbol needs to be in the dynamic symbol table.
 471   bool needs_dynsym_entry_ : 1;
 472   // True if we've seen this symbol in a dynamic object.
 473   bool in_dyn_ : 1;
 474   // True if the symbol has an entry in the GOT section.
 475   bool has_got_offset_ : 1;
 476   // True if the symbol has an entry in the PLT section.
 477   bool has_plt_offset_ : 1;
 478   // True if there is a warning for this symbol.
 479   bool has_warning_ : 1;
 480 };
 481
 482 // The parts of a symbol which are size specific.  Using a template
 483 // derived class like this helps us use less space on a 32-bit system.
 484
 485 template<int size>
 486 class Sized_symbol : public Symbol
 487 {
 488  public:
 489   typedef typename elfcpp::Elf_types<size>::Elf_Addr Value_type;
 490   typedef typename elfcpp::Elf_types<size>::Elf_WXword Size_type;
 491
 492   Sized_symbol()
 493   { }
 494
 495   // Initialize fields from an ELF symbol in OBJECT.
 496   template<bool big_endian>
 497   void
 498   init(const char *name, const char* version, Object* object,
 499        const elfcpp::Sym<size, big_endian>&);
 500
 501   // Initialize fields for an Output_data.
 502   void
 503   init(const char* name, Output_data*, Value_type value, Size_type symsize,
 504        elfcpp::STT, elfcpp::STB, elfcpp::STV, unsigned char nonvis,
 505        bool offset_is_from_end);
 506
 507   // Initialize fields for an Output_segment.
 508   void
 509   init(const char* name, Output_segment*, Value_type value, Size_type symsize,
 510        elfcpp::STT, elfcpp::STB, elfcpp::STV, unsigned char nonvis,
 511        Segment_offset_base offset_base);
 512
 513   // Initialize fields for a constant.
 514   void
 515   init(const char* name, Value_type value, Size_type symsize,
 516        elfcpp::STT, elfcpp::STB, elfcpp::STV, unsigned char nonvis);
 517
 518   // Override existing symbol.
 519   template<bool big_endian>
 520   void
 521   override(const elfcpp::Sym<size, big_endian>&, Object* object,
 522            const char* version);
 523
 524   // Return the symbol's value.
 525   Value_type
 526   value() const
 527   { return this->value_; }
 528
 529   // Return the symbol's size (we can't call this 'size' because that
 530   // is a template parameter).
 531   Size_type
 532   symsize() const
 533   { return this->symsize_; }
 534
 535   // Set the symbol size.  This is used when resolving common symbols.
 536   void
 537   set_symsize(Size_type symsize)
 538   { this->symsize_ = symsize; }
 539
 540   // Set the symbol value.  This is called when we store the final
 541   // values of the symbols into the symbol table.
 542   void
 543   set_value(Value_type value)
 544   { this->value_ = value; }
 545
 546  private:
 547   Sized_symbol(const Sized_symbol&);
 548   Sized_symbol& operator=(const Sized_symbol&);
 549
 550   // Symbol value.  Before Layout::finalize this is the offset in the
 551   // input section.  This is set to the final value during
 552   // Layout::finalize.
 553   Value_type value_;
 554   // Symbol size.
 555   Size_type symsize_;
 556 };
 557
 558 // A struct describing a symbol defined by the linker, where the value
 559 // of the symbol is defined based on an output section.  This is used
 560 // for symbols defined by the linker, like "_init_array_start".
 561
 562 struct Define_symbol_in_section
 563 {
 564   // The symbol name.
 565   const char* name;
 566   // The name of the output section with which this symbol should be
 567   // associated.  If there is no output section with that name, the
 568   // symbol will be defined as zero.
 569   const char* output_section;
 570   // The offset of the symbol within the output section.  This is an
 571   // offset from the start of the output section, unless start_at_end
 572   // is true, in which case this is an offset from the end of the
 573   // output section.
 574   uint64_t value;
 575   // The size of the symbol.
 576   uint64_t size;
 577   // The symbol type.
 578   elfcpp::STT type;
 579   // The symbol binding.
 580   elfcpp::STB binding;
 581   // The symbol visibility.
 582   elfcpp::STV visibility;
 583   // The rest of the st_other field.
 584   unsigned char nonvis;
 585   // If true, the value field is an offset from the end of the output
 586   // section.
 587   bool offset_is_from_end;
 588   // If true, this symbol is defined only if we see a reference to it.
 589   bool only_if_ref;
 590 };
 591
 592 // A struct describing a symbol defined by the linker, where the value
 593 // of the symbol is defined based on a segment.  This is used for
 594 // symbols defined by the linker, like "_end".  We describe the
 595 // segment with which the symbol should be associated by its
 596 // characteristics.  If no segment meets these characteristics, the
 597 // symbol will be defined as zero.  If there is more than one segment
 598 // which meets these characteristics, we will use the first one.
 599
 600 struct Define_symbol_in_segment
 601 {
 602   // The symbol name.
 603   const char* name;
 604   // The segment type where the symbol should be defined, typically
 605   // PT_LOAD.
 606   elfcpp::PT segment_type;
 607   // Bitmask of segment flags which must be set.
 608   elfcpp::PF segment_flags_set;
 609   // Bitmask of segment flags which must be clear.
 610   elfcpp::PF segment_flags_clear;
 611   // The offset of the symbol within the segment.  The offset is
 612   // calculated from the position set by offset_base.
 613   uint64_t value;
 614   // The size of the symbol.
 615   uint64_t size;
 616   // The symbol type.
 617   elfcpp::STT type;
 618   // The symbol binding.
 619   elfcpp::STB binding;
 620   // The symbol visibility.
 621   elfcpp::STV visibility;
 622   // The rest of the st_other field.
 623   unsigned char nonvis;
 624   // The base from which we compute the offset.
 625   Symbol::Segment_offset_base offset_base;
 626   // If true, this symbol is defined only if we see a reference to it.
 627   bool only_if_ref;
 628 };
 629
 630 // This class manages warnings.  Warnings are a GNU extension.  When
 631 // we see a section named .gnu.warning.SYM in an object file, and if
 632 // we wind using the definition of SYM from that object file, then we
 633 // will issue a warning for any relocation against SYM from a
 634 // different object file.  The text of the warning is the contents of
 635 // the section.  This is not precisely the definition used by the old
 636 // GNU linker; the old GNU linker treated an occurrence of
 637 // .gnu.warning.SYM as defining a warning symbol.  A warning symbol
 638 // would trigger a warning on any reference.  However, it was
 639 // inconsistent in that a warning in a dynamic object only triggered
 640 // if there was no definition in a regular object.  This linker is
 641 // different in that we only issue a warning if we use the symbol
 642 // definition from the same object file as the warning section.
 643
 644 class Warnings
 645 {
 646  public:
 647   Warnings()
 648     : warnings_()
 649   { }
 650
 651   // Add a warning for symbol NAME in section SHNDX in object OBJ.
 652   void
 653   add_warning(Symbol_table* symtab, const char* name, Object* obj,
 654               unsigned int shndx);
 655
 656   // For each symbol for which we should give a warning, make a note
 657   // on the symbol.
 658   void
 659   note_warnings(Symbol_table* symtab);
 660
 661   // Issue a warning for a reference to SYM at LOCATION.
 662   void
 663   issue_warning(const Symbol* sym, const std::string& location) const;
 664
 665  private:
 666   Warnings(const Warnings&);
 667   Warnings& operator=(const Warnings&);
 668
 669   // What we need to know to get the warning text.
 670   struct Warning_location
 671   {
 672     // The object the warning is in.
 673     Object* object;
 674     // The index of the warning section.
 675     unsigned int shndx;
 676     // The warning text if we have already loaded it.
 677     std::string text;
 678
 679     Warning_location()
 680       : object(NULL), shndx(0), text()
 681     { }
 682
 683     void
 684     set(Object* o, unsigned int s)
 685     {
 686       this->object = o;
 687       this->shndx = s;
 688     }
 689
 690     void
 691     set_text(const char* t, off_t l)
 692     { this->text.assign(t, l); }
 693   };
 694
 695   // A mapping from warning symbol names (canonicalized in
 696   // Symbol_table's namepool_ field) to
 697   typedef Unordered_map<const char*, Warning_location> Warning_table;
 698
 699   Warning_table warnings_;
 700 };
 701
 702 // The main linker symbol table.
 703
 704 class Symbol_table
 705 {
 706  public:
 707   Symbol_table();
 708
 709   ~Symbol_table();
 710
 711   // Add COUNT external symbols from the relocatable object RELOBJ to
 712   // the symbol table.  SYMS is the symbols, SYM_NAMES is their names,
 713   // SYM_NAME_SIZE is the size of SYM_NAMES.  This sets SYMPOINTERS to
 714   // point to the symbols in the symbol table.
 715   template<int size, bool big_endian>
 716   void
 717   add_from_relobj(Sized_relobj<size, big_endian>* relobj,
 718                   const unsigned char* syms, size_t count,
 719                   const char* sym_names, size_t sym_name_size,
 720                   Symbol** sympointers);
 721
 722   // Add COUNT dynamic symbols from the dynamic object DYNOBJ to the
 723   // symbol table.  SYMS is the symbols.  SYM_NAMES is their names.
 724   // SYM_NAME_SIZE is the size of SYM_NAMES.  The other parameters are
 725   // symbol version data.
 726   template<int size, bool big_endian>
 727   void
 728   add_from_dynobj(Sized_dynobj<size, big_endian>* dynobj,
 729                   const unsigned char* syms, size_t count,
 730                   const char* sym_names, size_t sym_name_size,
 731                   const unsigned char* versym, size_t versym_size,
 732                   const std::vector<const char*>*);
 733
 734   // Define a special symbol based on an Output_data.  It is a
 735   // multiple definition error if this symbol is already defined.
 736   Symbol*
 737   define_in_output_data(const Target*, const char* name, const char* version,
 738                         Output_data*, uint64_t value, uint64_t symsize,
 739                         elfcpp::STT type, elfcpp::STB binding,
 740                         elfcpp::STV visibility, unsigned char nonvis,
 741                         bool offset_is_from_end, bool only_if_ref);
 742
 743   // Define a special symbol based on an Output_segment.  It is a
 744   // multiple definition error if this symbol is already defined.
 745   Symbol*
 746   define_in_output_segment(const Target*, const char* name,
 747                            const char* version, Output_segment*,
 748                            uint64_t value, uint64_t symsize,
 749                            elfcpp::STT type, elfcpp::STB binding,
 750                            elfcpp::STV visibility, unsigned char nonvis,
 751                            Symbol::Segment_offset_base, bool only_if_ref);
 752
 753   // Define a special symbol with a constant value.  It is a multiple
 754   // definition error if this symbol is already defined.
 755   Symbol*
 756   define_as_constant(const Target*, const char* name, const char* version,
 757                      uint64_t value, uint64_t symsize, elfcpp::STT type,
 758                      elfcpp::STB binding, elfcpp::STV visibility,
 759                      unsigned char nonvis, bool only_if_ref);
 760
 761   // Define a set of symbols in output sections.
 762   void
 763   define_symbols(const Layout*, const Target*, int count,
 764                  const Define_symbol_in_section*);
 765
 766   // Define a set of symbols in output segments.
 767   void
 768   define_symbols(const Layout*, const Target*, int count,
 769                  const Define_symbol_in_segment*);
 770
 771   // Look up a symbol.
 772   Symbol*
 773   lookup(const char*, const char* version = NULL) const;
 774
 775   // Return the real symbol associated with the forwarder symbol FROM.
 776   Symbol*
 777   resolve_forwards(const Symbol* from) const;
 778
 779   // Return the bitsize (32 or 64) of the symbols in the table.
 780   int
 781   get_size() const
 782   { return this->size_; }
 783
 784   // Return the sized version of a symbol in this table.
 785   template<int size>
 786   Sized_symbol<size>*
 787   get_sized_symbol(Symbol* ACCEPT_SIZE) const;
 788
 789   template<int size>
 790   const Sized_symbol<size>*
 791   get_sized_symbol(const Symbol* ACCEPT_SIZE) const;
 792
 793   // Return the count of undefined symbols seen.
 794   int
 795   saw_undefined() const
 796   { return this->saw_undefined_; }
 797
 798   // Allocate the common symbols
 799   void
 800   allocate_commons(const General_options&, Layout*);
 801
 802   // Add a warning for symbol NAME in section SHNDX in object OBJ.
 803   void
 804   add_warning(const char* name, Object* obj, unsigned int shndx)
 805   { this->warnings_.add_warning(this, name, obj, shndx); }
 806
 807   // Canonicalize a symbol name for use in the hash table.
 808   const char*
 809   canonicalize_name(const char* name)
 810   { return this->namepool_.add(name, NULL); }
 811
 812   // Possibly issue a warning for a reference to SYM at LOCATION which
 813   // is in OBJ.
 814   void
 815   issue_warning(const Symbol* sym, const std::string& location) const
 816   { this->warnings_.issue_warning(sym, location); }
 817
 818   // Set the dynamic symbol indexes.  INDEX is the index of the first
 819   // global dynamic symbol.  Pointers to the symbols are stored into
 820   // the vector.  The names are stored into the Stringpool.  This
 821   // returns an updated dynamic symbol index.
 822   unsigned int
 823   set_dynsym_indexes(const General_options*, const Target*, unsigned int index,
 824                      std::vector<Symbol*>*, Stringpool*, Versions*);
 825
 826   // Finalize the symbol table after we have set the final addresses
 827   // of all the input sections.  This sets the final symbol indexes,
 828   // values and adds the names to *POOL.  INDEX is the index of the
 829   // first global symbol.  OFF is the file offset of the global symbol
 830   // table, DYNOFF is the offset of the globals in the dynamic symbol
 831   // table, DYN_GLOBAL_INDEX is the index of the first global dynamic
 832   // symbol, and DYNCOUNT is the number of global dynamic symbols.
 833   // This records the parameters, and returns the new file offset.
 834   off_t
 835   finalize(unsigned int index, off_t off, off_t dynoff,
 836            size_t dyn_global_index, size_t dyncount, Stringpool* pool);
 837
 838   // Write out the global symbols.
 839   void
 840   write_globals(const Target*, const Stringpool*, const Stringpool*,
 841                 Output_file*) const;
 842
 843   // Write out a section symbol.  Return the updated offset.
 844   void
 845   write_section_symbol(const Target*, const Output_section*, Output_file*,
 846                        off_t) const;
 847
 848  private:
 849   Symbol_table(const Symbol_table&);
 850   Symbol_table& operator=(const Symbol_table&);
 851
 852   // Set the size (32 or 64) of the symbols in the table.
 853   void
 854   set_size(int size)
 855   { this->size_ = size; }
 856
 857   // Make FROM a forwarder symbol to TO.
 858   void
 859   make_forwarder(Symbol* from, Symbol* to);
 860
 861   // Add a symbol.
 862   template<int size, bool big_endian>
 863   Symbol*
 864   add_from_object(Object*, const char *name, Stringpool::Key name_key,
 865                   const char *version, Stringpool::Key version_key,
 866                   bool def, const elfcpp::Sym<size, big_endian>& sym);
 867
 868   // Resolve symbols.
 869   template<int size, bool big_endian>
 870   static void
 871   resolve(Sized_symbol<size>* to,
 872           const elfcpp::Sym<size, big_endian>& sym,
 873           Object*, const char* version);
 874
 875   template<int size, bool big_endian>
 876   static void
 877   resolve(Sized_symbol<size>* to, const Sized_symbol<size>* from,
 878           const char* version ACCEPT_SIZE_ENDIAN);
 879
 880   // Define a special symbol.
 881   template<int size, bool big_endian>
 882   Sized_symbol<size>*
 883   define_special_symbol(const Target* target, const char* name,
 884                         const char* version, bool only_if_ref
 885                         ACCEPT_SIZE_ENDIAN);
 886
 887   // Define a symbol in an Output_data, sized version.
 888   template<int size>
 889   Sized_symbol<size>*
 890   do_define_in_output_data(const Target*, const char* name,
 891                            const char* version, Output_data*,
 892                            typename elfcpp::Elf_types<size>::Elf_Addr value,
 893                            typename elfcpp::Elf_types<size>::Elf_WXword ssize,
 894                            elfcpp::STT type, elfcpp::STB binding,
 895                            elfcpp::STV visibility, unsigned char nonvis,
 896                            bool offset_is_from_end, bool only_if_ref);
 897
 898   // Define a symbol in an Output_segment, sized version.
 899   template<int size>
 900   Sized_symbol<size>*
 901   do_define_in_output_segment(
 902     const Target*, const char* name, const char* version, Output_segment* os,
 903     typename elfcpp::Elf_types<size>::Elf_Addr value,
 904     typename elfcpp::Elf_types<size>::Elf_WXword ssize,
 905     elfcpp::STT type, elfcpp::STB binding,
 906     elfcpp::STV visibility, unsigned char nonvis,
 907     Symbol::Segment_offset_base offset_base, bool only_if_ref);
 908
 909   // Define a symbol as a constant, sized version.
 910   template<int size>
 911   Sized_symbol<size>*
 912   do_define_as_constant(
 913     const Target*, const char* name, const char* version,
 914     typename elfcpp::Elf_types<size>::Elf_Addr value,
 915     typename elfcpp::Elf_types<size>::Elf_WXword ssize,
 916     elfcpp::STT type, elfcpp::STB binding,
 917     elfcpp::STV visibility, unsigned char nonvis,
 918     bool only_if_ref);
 919
 920   // Allocate the common symbols, sized version.
 921   template<int size>
 922   void
 923   do_allocate_commons(const General_options&, Layout*);
 924
 925   // Finalize symbols specialized for size.
 926   template<int size>
 927   off_t
 928   sized_finalize(unsigned int, off_t, Stringpool*);
 929
 930   // Write globals specialized for size and endianness.
 931   template<int size, bool big_endian>
 932   void
 933   sized_write_globals(const Target*, const Stringpool*, const Stringpool*,
 934                       Output_file*) const;
 935
 936   // Write out a symbol to P.
 937   template<int size, bool big_endian>
 938   void
 939   sized_write_symbol(Sized_symbol<size>*, unsigned int shndx,
 940                      const Stringpool*, unsigned char* p
 941                      ACCEPT_SIZE_ENDIAN) const;
 942
 943   // Write out a section symbol, specialized for size and endianness.
 944   template<int size, bool big_endian>
 945   void
 946   sized_write_section_symbol(const Output_section*, Output_file*, off_t) const;
 947
 948   // The type of the symbol hash table.
 949
 950   typedef std::pair<Stringpool::Key, Stringpool::Key> Symbol_table_key;
 951
 952   struct Symbol_table_hash
 953   {
 954     size_t
 955     operator()(const Symbol_table_key&) const;
 956   };
 957
 958   struct Symbol_table_eq
 959   {
 960     bool
 961     operator()(const Symbol_table_key&, const Symbol_table_key&) const;
 962   };
 963
 964   typedef Unordered_map<Symbol_table_key, Symbol*, Symbol_table_hash,
 965                         Symbol_table_eq> Symbol_table_type;
 966
 967   // The type of the list of common symbols.
 968
 969   typedef std::vector<Symbol*> Commons_type;
 970
 971   // The size of the symbols in the symbol table (32 or 64).
 972   int size_;
 973
 974   // We increment this every time we see a new undefined symbol, for
 975   // use in archive groups.
 976   int saw_undefined_;
 977
 978   // The index of the first global symbol in the output file.
 979   unsigned int first_global_index_;
 980
 981   // The file offset within the output symtab section where we should
 982   // write the table.
 983   off_t offset_;
 984
 985   // The number of global symbols we want to write out.
 986   size_t output_count_;
 987
 988   // The file offset of the global dynamic symbols, or 0 if none.
 989   off_t dynamic_offset_;
 990
 991   // The index of the first global dynamic symbol.
 992   unsigned int first_dynamic_global_index_;
 993
 994   // The number of global dynamic symbols, or 0 if none.
 995   off_t dynamic_count_;
 996
 997   // The symbol hash table.
 998   Symbol_table_type table_;
 999
1000   // A pool of symbol names.  This is used for all global symbols.
1001   // Entries in the hash table point into this pool.
1002   Stringpool namepool_;
1003
1004   // Forwarding symbols.
1005   Unordered_map<const Symbol*, Symbol*> forwarders_;
1006
1007   // We don't expect there to be very many common symbols, so we keep
1008   // a list of them.  When we find a common symbol we add it to this
1009   // list.  It is possible that by the time we process the list the
1010   // symbol is no longer a common symbol.  It may also have become a
1011   // forwarder.
1012   Commons_type commons_;
1013
1014   // Manage symbol warnings.
1015   Warnings warnings_;
1016 };
1017
1018 // We inline get_sized_symbol for efficiency.
1019
1020 template<int size>
1021 Sized_symbol<size>*
1022 Symbol_table::get_sized_symbol(Symbol* sym ACCEPT_SIZE) const
1023 {
1024   gold_assert(size == this->get_size());
1025   return static_cast<Sized_symbol<size>*>(sym);
1026 }
1027
1028 template<int size>
1029 const Sized_symbol<size>*
1030 Symbol_table::get_sized_symbol(const Symbol* sym ACCEPT_SIZE) const
1031 {
1032   gold_assert(size == this->get_size());
1033   return static_cast<const Sized_symbol<size>*>(sym);
1034 }
1035
1036 } // End namespace gold.
1037
1038 #endif // !defined(GOLD_SYMTAB_H)