Copy in_reg and in_dyn when resolving NAME/VERSION with NAME/NULL.

[binutils.git] / gold / symtab.cc

// symtab.cc -- the gold symbol table

#include "gold.h"

#include <stdint.h>
#include <string>
#include <utility>

#include "object.h"
#include "dynobj.h"
#include "output.h"
#include "target.h"
#include "workqueue.h"
#include "symtab.h"

namespace gold
{

// Class Symbol.

// Initialize fields in Symbol.  This initializes everything except u_
// and source_.

void
Symbol::init_fields(const char* name, const char* version,
                    elfcpp::STT type, elfcpp::STB binding,
                    elfcpp::STV visibility, unsigned char nonvis)
{
  this->name_ = name;
  this->version_ = version;
  this->symtab_index_ = 0;
  this->dynsym_index_ = 0;
  this->got_offset_ = 0;
  this->plt_offset_ = 0;
  this->type_ = type;
  this->binding_ = binding;
  this->visibility_ = visibility;
  this->nonvis_ = nonvis;
  this->is_target_special_ = false;
  this->is_def_ = false;
  this->is_forwarder_ = false;
  this->needs_dynsym_entry_ = false;
  this->in_reg_ = false;
  this->in_dyn_ = false;
  this->has_got_offset_ = false;
  this->has_plt_offset_ = false;
  this->has_warning_ = false;
}

// Initialize the fields in the base class Symbol for SYM in OBJECT.

template<int size, bool big_endian>
void
Symbol::init_base(const char* name, const char* version, Object* object,
                  const elfcpp::Sym<size, big_endian>& sym)
{
  this->init_fields(name, version, sym.get_st_type(), sym.get_st_bind(),
                    sym.get_st_visibility(), sym.get_st_nonvis());
  this->u_.from_object.object = object;
  // FIXME: Handle SHN_XINDEX.
  this->u_.from_object.shndx = sym.get_st_shndx();
  this->source_ = FROM_OBJECT;
  this->in_reg_ = !object->is_dynamic();
  this->in_dyn_ = object->is_dynamic();
}

// Initialize the fields in the base class Symbol for a symbol defined
// in an Output_data.

void
Symbol::init_base(const char* name, Output_data* od, elfcpp::STT type,
                  elfcpp::STB binding, elfcpp::STV visibility,
                  unsigned char nonvis, bool offset_is_from_end)
{
  this->init_fields(name, NULL, type, binding, visibility, nonvis);
  this->u_.in_output_data.output_data = od;
  this->u_.in_output_data.offset_is_from_end = offset_is_from_end;
  this->source_ = IN_OUTPUT_DATA;
  this->in_reg_ = true;
}

// Initialize the fields in the base class Symbol for a symbol defined
// in an Output_segment.

void
Symbol::init_base(const char* name, Output_segment* os, elfcpp::STT type,
                  elfcpp::STB binding, elfcpp::STV visibility,
                  unsigned char nonvis, Segment_offset_base offset_base)
{
  this->init_fields(name, NULL, type, binding, visibility, nonvis);
  this->u_.in_output_segment.output_segment = os;
  this->u_.in_output_segment.offset_base = offset_base;
  this->source_ = IN_OUTPUT_SEGMENT;
  this->in_reg_ = true;
}

// Initialize the fields in the base class Symbol for a symbol defined
// as a constant.

void
Symbol::init_base(const char* name, elfcpp::STT type,
                  elfcpp::STB binding, elfcpp::STV visibility,
                  unsigned char nonvis)
{
  this->init_fields(name, NULL, type, binding, visibility, nonvis);
  this->source_ = CONSTANT;
  this->in_reg_ = true;
}

// Initialize the fields in Sized_symbol for SYM in OBJECT.

template<int size>
template<bool big_endian>
void
Sized_symbol<size>::init(const char* name, const char* version, Object* object,
                         const elfcpp::Sym<size, big_endian>& sym)
{
  this->init_base(name, version, object, sym);
  this->value_ = sym.get_st_value();
  this->symsize_ = sym.get_st_size();
}

// Initialize the fields in Sized_symbol for a symbol defined in an
// Output_data.

template<int size>
void
Sized_symbol<size>::init(const char* name, Output_data* od,
                         Value_type value, Size_type symsize,
                         elfcpp::STT type, elfcpp::STB binding,
                         elfcpp::STV visibility, unsigned char nonvis,
                         bool offset_is_from_end)
{
  this->init_base(name, od, type, binding, visibility, nonvis,
                  offset_is_from_end);
  this->value_ = value;
  this->symsize_ = symsize;
}

// Initialize the fields in Sized_symbol for a symbol defined in an
// Output_segment.

template<int size>
void
Sized_symbol<size>::init(const char* name, Output_segment* os,
                         Value_type value, Size_type symsize,
                         elfcpp::STT type, elfcpp::STB binding,
                         elfcpp::STV visibility, unsigned char nonvis,
                         Segment_offset_base offset_base)
{
  this->init_base(name, os, type, binding, visibility, nonvis, offset_base);
  this->value_ = value;
  this->symsize_ = symsize;
}

// Initialize the fields in Sized_symbol for a symbol defined as a
// constant.

template<int size>
void
Sized_symbol<size>::init(const char* name, Value_type value, Size_type symsize,
                         elfcpp::STT type, elfcpp::STB binding,
                         elfcpp::STV visibility, unsigned char nonvis)
{
  this->init_base(name, type, binding, visibility, nonvis);
  this->value_ = value;
  this->symsize_ = symsize;
}

// Class Symbol_table.

Symbol_table::Symbol_table()
  : size_(0), saw_undefined_(0), offset_(0), table_(), namepool_(),
    forwarders_(), commons_(), warnings_()
{
}

Symbol_table::~Symbol_table()
{
}

// The hash function.  The key is always canonicalized, so we use a
// simple combination of the pointers.

size_t
Symbol_table::Symbol_table_hash::operator()(const Symbol_table_key& key) const
{
  return key.first ^ key.second;
}

// The symbol table key equality function.  This is only called with
// canonicalized name and version strings, so we can use pointer
// comparison.

bool
Symbol_table::Symbol_table_eq::operator()(const Symbol_table_key& k1,
                                          const Symbol_table_key& k2) const
{
  return k1.first == k2.first && k1.second == k2.second;
}

// Make TO a symbol which forwards to FROM.  

void
Symbol_table::make_forwarder(Symbol* from, Symbol* to)
{
  gold_assert(from != to);
  gold_assert(!from->is_forwarder() && !to->is_forwarder());
  this->forwarders_[from] = to;
  from->set_forwarder();
}

// Resolve the forwards from FROM, returning the real symbol.

Symbol*
Symbol_table::resolve_forwards(const Symbol* from) const
{
  gold_assert(from->is_forwarder());
  Unordered_map<const Symbol*, Symbol*>::const_iterator p =
    this->forwarders_.find(from);
  gold_assert(p != this->forwarders_.end());
  return p->second;
}

// Look up a symbol by name.

Symbol*
Symbol_table::lookup(const char* name, const char* version) const
{
  Stringpool::Key name_key;
  name = this->namepool_.find(name, &name_key);
  if (name == NULL)
    return NULL;

  Stringpool::Key version_key = 0;
  if (version != NULL)
    {
      version = this->namepool_.find(version, &version_key);
      if (version == NULL)
        return NULL;
    }

  Symbol_table_key key(name_key, version_key);
  Symbol_table::Symbol_table_type::const_iterator p = this->table_.find(key);
  if (p == this->table_.end())
    return NULL;
  return p->second;
}

// Resolve a Symbol with another Symbol.  This is only used in the
// unusual case where there are references to both an unversioned
// symbol and a symbol with a version, and we then discover that that
// version is the default version.  Because this is unusual, we do
// this the slow way, by converting back to an ELF symbol.

template<int size, bool big_endian>
void
Symbol_table::resolve(Sized_symbol<size>* to, const Sized_symbol<size>* from,
                      const char* version ACCEPT_SIZE_ENDIAN)
{
  unsigned char buf[elfcpp::Elf_sizes<size>::sym_size];
  elfcpp::Sym_write<size, big_endian> esym(buf);
  // We don't bother to set the st_name field.
  esym.put_st_value(from->value());
  esym.put_st_size(from->symsize());
  esym.put_st_info(from->binding(), from->type());
  esym.put_st_other(from->visibility(), from->nonvis());
  esym.put_st_shndx(from->shndx());
  Symbol_table::resolve(to, esym.sym(), from->object(), version);
  if (from->in_reg())
    to->set_in_reg();
  if (from->in_dyn())
    to->set_in_dyn();
}

// Add one symbol from OBJECT to the symbol table.  NAME is symbol
// name and VERSION is the version; both are canonicalized.  DEF is
// whether this is the default version.

// If DEF is true, then this is the definition of a default version of
// a symbol.  That means that any lookup of NAME/NULL and any lookup
// of NAME/VERSION should always return the same symbol.  This is
// obvious for references, but in particular we want to do this for
// definitions: overriding NAME/NULL should also override
// NAME/VERSION.  If we don't do that, it would be very hard to
// override functions in a shared library which uses versioning.

// We implement this by simply making both entries in the hash table
// point to the same Symbol structure.  That is easy enough if this is
// the first time we see NAME/NULL or NAME/VERSION, but it is possible
// that we have seen both already, in which case they will both have
// independent entries in the symbol table.  We can't simply change
// the symbol table entry, because we have pointers to the entries
// attached to the object files.  So we mark the entry attached to the
// object file as a forwarder, and record it in the forwarders_ map.
// Note that entries in the hash table will never be marked as
// forwarders.

template<int size, bool big_endian>
Symbol*
Symbol_table::add_from_object(Object* object,
                              const char *name,
                              Stringpool::Key name_key,
                              const char *version,
                              Stringpool::Key version_key,
                              bool def,
                              const elfcpp::Sym<size, big_endian>& sym)
{
  Symbol* const snull = NULL;
  std::pair<typename Symbol_table_type::iterator, bool> ins =
    this->table_.insert(std::make_pair(std::make_pair(name_key, version_key),
                                       snull));

  std::pair<typename Symbol_table_type::iterator, bool> insdef =
    std::make_pair(this->table_.end(), false);
  if (def)
    {
      const Stringpool::Key vnull_key = 0;
      insdef = this->table_.insert(std::make_pair(std::make_pair(name_key,
                                                                 vnull_key),
                                                  snull));
    }

  // ins.first: an iterator, which is a pointer to a pair.
  // ins.first->first: the key (a pair of name and version).
  // ins.first->second: the value (Symbol*).
  // ins.second: true if new entry was inserted, false if not.

  Sized_symbol<size>* ret;
  bool was_undefined;
  bool was_common;
  if (!ins.second)
    {
      // We already have an entry for NAME/VERSION.
      ret = this->get_sized_symbol SELECT_SIZE_NAME(size) (ins.first->second
                                                           SELECT_SIZE(size));
      gold_assert(ret != NULL);

      was_undefined = ret->is_undefined();
      was_common = ret->is_common();

      Symbol_table::resolve(ret, sym, object, version);

      if (def)
        {
          if (insdef.second)
            {
              // This is the first time we have seen NAME/NULL.  Make
              // NAME/NULL point to NAME/VERSION.
              insdef.first->second = ret;
            }
          else if (insdef.first->second != ret)
            {
              // This is the unfortunate case where we already have
              // entries for both NAME/VERSION and NAME/NULL.
              const Sized_symbol<size>* sym2;
              sym2 = this->get_sized_symbol SELECT_SIZE_NAME(size) (
                insdef.first->second
                SELECT_SIZE(size));
              Symbol_table::resolve SELECT_SIZE_ENDIAN_NAME(size, big_endian) (
                ret, sym2, version SELECT_SIZE_ENDIAN(size, big_endian));
              this->make_forwarder(insdef.first->second, ret);
              insdef.first->second = ret;
            }
        }
    }
  else
    {
      // This is the first time we have seen NAME/VERSION.
      gold_assert(ins.first->second == NULL);

      was_undefined = false;
      was_common = false;

      if (def && !insdef.second)
        {
          // We already have an entry for NAME/NULL.  If we override
          // it, then change it to NAME/VERSION.
          ret = this->get_sized_symbol SELECT_SIZE_NAME(size) (
              insdef.first->second
              SELECT_SIZE(size));
          Symbol_table::resolve(ret, sym, object, version);
          ins.first->second = ret;
        }
      else
        {
          Sized_target<size, big_endian>* target =
            object->sized_target SELECT_SIZE_ENDIAN_NAME(size, big_endian) (
                SELECT_SIZE_ENDIAN_ONLY(size, big_endian));
          if (!target->has_make_symbol())
            ret = new Sized_symbol<size>();
          else
            {
              ret = target->make_symbol();
              if (ret == NULL)
                {
                  // This means that we don't want a symbol table
                  // entry after all.
                  if (!def)
                    this->table_.erase(ins.first);
                  else
                    {
                      this->table_.erase(insdef.first);
                      // Inserting insdef invalidated ins.
                      this->table_.erase(std::make_pair(name_key,
                                                        version_key));
                    }
                  return NULL;
                }
            }

          ret->init(name, version, object, sym);

          ins.first->second = ret;
          if (def)
            {
              // This is the first time we have seen NAME/NULL.  Point
              // it at the new entry for NAME/VERSION.
              gold_assert(insdef.second);
              insdef.first->second = ret;
            }
        }
    }

  // Record every time we see a new undefined symbol, to speed up
  // archive groups.
  if (!was_undefined && ret->is_undefined())
    ++this->saw_undefined_;

  // Keep track of common symbols, to speed up common symbol
  // allocation.
  if (!was_common && ret->is_common())
    this->commons_.push_back(ret);

  return ret;
}

// Add all the symbols in a relocatable object to the hash table.

template<int size, bool big_endian>
void
Symbol_table::add_from_relobj(
    Sized_relobj<size, big_endian>* relobj,
    const unsigned char* syms,
    size_t count,
    const char* sym_names,
    size_t sym_name_size,
    Symbol** sympointers)
{
  // We take the size from the first object we see.
  if (this->get_size() == 0)
    this->set_size(size);

  if (size != this->get_size() || size != relobj->target()->get_size())
    {
      fprintf(stderr, _("%s: %s: mixing 32-bit and 64-bit ELF objects\n"),
              program_name, relobj->name().c_str());
      gold_exit(false);
    }

  const int sym_size = elfcpp::Elf_sizes<size>::sym_size;

  const unsigned char* p = syms;
  for (size_t i = 0; i < count; ++i, p += sym_size)
    {
      elfcpp::Sym<size, big_endian> sym(p);
      elfcpp::Sym<size, big_endian>* psym = &sym;

      unsigned int st_name = psym->get_st_name();
      if (st_name >= sym_name_size)
        {
          fprintf(stderr,
                  _("%s: %s: bad global symbol name offset %u at %lu\n"),
                  program_name, relobj->name().c_str(), st_name,
                  static_cast<unsigned long>(i));
          gold_exit(false);
        }

      const char* name = sym_names + st_name;

      // A symbol defined in a section which we are not including must
      // be treated as an undefined symbol.
      unsigned char symbuf[sym_size];
      elfcpp::Sym<size, big_endian> sym2(symbuf);
      unsigned int st_shndx = psym->get_st_shndx();
      if (st_shndx != elfcpp::SHN_UNDEF
          && st_shndx < elfcpp::SHN_LORESERVE
          && !relobj->is_section_included(st_shndx))
        {
          memcpy(symbuf, p, sym_size);
          elfcpp::Sym_write<size, big_endian> sw(symbuf);
          sw.put_st_shndx(elfcpp::SHN_UNDEF);
          psym = &sym2;
        }

      // In an object file, an '@' in the name separates the symbol
      // name from the version name.  If there are two '@' characters,
      // this is the default version.
      const char* ver = strchr(name, '@');

      Symbol* res;
      if (ver == NULL)
        {
          Stringpool::Key name_key;
          name = this->namepool_.add(name, &name_key);
          res = this->add_from_object(relobj, name, name_key, NULL, 0,
                                      false, *psym);
        }
      else
        {
          Stringpool::Key name_key;
          name = this->namepool_.add(name, ver - name, &name_key);

          bool def = false;
          ++ver;
          if (*ver == '@')
            {
              def = true;
              ++ver;
            }

          Stringpool::Key ver_key;
          ver = this->namepool_.add(ver, &ver_key);

          res = this->add_from_object(relobj, name, name_key, ver, ver_key,
                                      def, *psym);
        }

      *sympointers++ = res;
    }
}

// Add all the symbols in a dynamic object to the hash table.

template<int size, bool big_endian>
void
Symbol_table::add_from_dynobj(
    Sized_dynobj<size, big_endian>* dynobj,
    const unsigned char* syms,
    size_t count,
    const char* sym_names,
    size_t sym_name_size,
    const unsigned char* versym,
    size_t versym_size,
    const std::vector<const char*>* version_map)
{
  // We take the size from the first object we see.
  if (this->get_size() == 0)
    this->set_size(size);

  if (size != this->get_size() || size != dynobj->target()->get_size())
    {
      fprintf(stderr, _("%s: %s: mixing 32-bit and 64-bit ELF objects\n"),
              program_name, dynobj->name().c_str());
      gold_exit(false);
    }

  if (versym != NULL && versym_size / 2 < count)
    {
      fprintf(stderr, _("%s: %s: too few symbol versions\n"),
              program_name, dynobj->name().c_str());
      gold_exit(false);
    }

  const int sym_size = elfcpp::Elf_sizes<size>::sym_size;

  const unsigned char* p = syms;
  const unsigned char* vs = versym;
  for (size_t i = 0; i < count; ++i, p += sym_size, vs += 2)
    {
      elfcpp::Sym<size, big_endian> sym(p);

      // Ignore symbols with local binding.
      if (sym.get_st_bind() == elfcpp::STB_LOCAL)
        continue;

      unsigned int st_name = sym.get_st_name();
      if (st_name >= sym_name_size)
        {
          fprintf(stderr, _("%s: %s: bad symbol name offset %u at %lu\n"),
                  program_name, dynobj->name().c_str(), st_name,
                  static_cast<unsigned long>(i));
          gold_exit(false);
        }

      const char* name = sym_names + st_name;

      if (versym == NULL)
        {
          Stringpool::Key name_key;
          name = this->namepool_.add(name, &name_key);
          this->add_from_object(dynobj, name, name_key, NULL, 0,
                                false, sym);
          continue;
        }

      // Read the version information.

      unsigned int v = elfcpp::Swap<16, big_endian>::readval(vs);

      bool hidden = (v & elfcpp::VERSYM_HIDDEN) != 0;
      v &= elfcpp::VERSYM_VERSION;

      if (v == static_cast<unsigned int>(elfcpp::VER_NDX_LOCAL))
        {
          // This symbol should not be visible outside the object.
          continue;
        }

      // At this point we are definitely going to add this symbol.
      Stringpool::Key name_key;
      name = this->namepool_.add(name, &name_key);

      if (v == static_cast<unsigned int>(elfcpp::VER_NDX_GLOBAL))
        {
          // This symbol does not have a version.
          this->add_from_object(dynobj, name, name_key, NULL, 0, false, sym);
          continue;
        }

      if (v >= version_map->size())
        {
          fprintf(stderr,
                  _("%s: %s: versym for symbol %zu out of range: %u\n"),
                  program_name, dynobj->name().c_str(), i, v);
          gold_exit(false);
        }

      const char* version = (*version_map)[v];
      if (version == NULL)
        {
          fprintf(stderr, _("%s: %s: versym for symbol %zu has no name: %u\n"),
                  program_name, dynobj->name().c_str(), i, v);
          gold_exit(false);
        }

      Stringpool::Key version_key;
      version = this->namepool_.add(version, &version_key);

      // If this is an absolute symbol, and the version name and
      // symbol name are the same, then this is the version definition
      // symbol.  These symbols exist to support using -u to pull in
      // particular versions.  We do not want to record a version for
      // them.
      if (sym.get_st_shndx() == elfcpp::SHN_ABS && name_key == version_key)
        {
          this->add_from_object(dynobj, name, name_key, NULL, 0, false, sym);
          continue;
        }

      const bool def = !hidden && sym.get_st_shndx() != elfcpp::SHN_UNDEF;

      this->add_from_object(dynobj, name, name_key, version, version_key,
                            def, sym);
    }
}

// Create and return a specially defined symbol.  If ONLY_IF_REF is
// true, then only create the symbol if there is a reference to it.

template<int size, bool big_endian>
Sized_symbol<size>*
Symbol_table::define_special_symbol(const Target* target, const char* name,
                                    const char* version, bool only_if_ref
                                    ACCEPT_SIZE_ENDIAN)
{
  gold_assert(this->size_ == size);

  Symbol* oldsym;
  Sized_symbol<size>* sym;

  if (only_if_ref)
    {
      oldsym = this->lookup(name, version);
      if (oldsym == NULL || !oldsym->is_undefined())
        return NULL;
      sym = NULL;

      // Canonicalize NAME and VERSION.
      name = oldsym->name();
      version = oldsym->version();
    }
  else
    {
      // Canonicalize NAME and VERSION.
      Stringpool::Key name_key;
      name = this->namepool_.add(name, &name_key);

      Stringpool::Key version_key = 0;
      if (version != NULL)
        version = this->namepool_.add(version, &version_key);

      Symbol* const snull = NULL;
      std::pair<typename Symbol_table_type::iterator, bool> ins =
        this->table_.insert(std::make_pair(std::make_pair(name_key,
                                                          version_key),
                                           snull));

      if (!ins.second)
        {
          // We already have a symbol table entry for NAME/VERSION.
          oldsym = ins.first->second;
          gold_assert(oldsym != NULL);
          sym = NULL;
        }
      else
        {
          // We haven't seen this symbol before.
          gold_assert(ins.first->second == NULL);

          if (!target->has_make_symbol())
            sym = new Sized_symbol<size>();
          else
            {
              gold_assert(target->get_size() == size);
              gold_assert(target->is_big_endian() ? big_endian : !big_endian);
              typedef Sized_target<size, big_endian> My_target;
              const My_target* sized_target =
                static_cast<const My_target*>(target);
              sym = sized_target->make_symbol();
              if (sym == NULL)
                return NULL;
            }

          ins.first->second = sym;
          oldsym = NULL;
        }
    }

  if (oldsym != NULL)
    {
      gold_assert(sym == NULL);

      sym = this->get_sized_symbol SELECT_SIZE_NAME(size) (oldsym
                                                           SELECT_SIZE(size));
      gold_assert(sym->source() == Symbol::FROM_OBJECT);
      const int old_shndx = sym->shndx();
      if (old_shndx != elfcpp::SHN_UNDEF
          && old_shndx != elfcpp::SHN_COMMON
          && !sym->object()->is_dynamic())
        {
          fprintf(stderr, "%s: linker defined: multiple definition of %s\n",
                  program_name, name);
          // FIXME: Report old location.  Record that we have seen an
          // error.
          return NULL;
        }

      // Our new definition is going to override the old reference.
    }

  return sym;
}

// Define a symbol based on an Output_data.

Symbol*
Symbol_table::define_in_output_data(const Target* target, const char* name,
                                    const char* version, Output_data* od,
                                    uint64_t value, uint64_t symsize,
                                    elfcpp::STT type, elfcpp::STB binding,
                                    elfcpp::STV visibility,
                                    unsigned char nonvis,
                                    bool offset_is_from_end,
                                    bool only_if_ref)
{
  gold_assert(target->get_size() == this->size_);
  if (this->size_ == 32)
    return this->do_define_in_output_data<32>(target, name, version, od, value,
                                              symsize, type, binding,
                                              visibility, nonvis,
                                              offset_is_from_end, only_if_ref);
  else if (this->size_ == 64)
    return this->do_define_in_output_data<64>(target, name, version, od, value,
                                              symsize, type, binding,
                                              visibility, nonvis,
                                              offset_is_from_end, only_if_ref);
  else
    gold_unreachable();
}

// Define a symbol in an Output_data, sized version.

template<int size>
Sized_symbol<size>*
Symbol_table::do_define_in_output_data(
    const Target* target,
    const char* name,
    const char* version,
    Output_data* od,
    typename elfcpp::Elf_types<size>::Elf_Addr value,
    typename elfcpp::Elf_types<size>::Elf_WXword symsize,
    elfcpp::STT type,
    elfcpp::STB binding,
    elfcpp::STV visibility,
    unsigned char nonvis,
    bool offset_is_from_end,
    bool only_if_ref)
{
  Sized_symbol<size>* sym;

  if (target->is_big_endian())
    sym = this->define_special_symbol SELECT_SIZE_ENDIAN_NAME(size, true) (
        target, name, version, only_if_ref
        SELECT_SIZE_ENDIAN(size, true));
  else
    sym = this->define_special_symbol SELECT_SIZE_ENDIAN_NAME(size, false) (
        target, name, version, only_if_ref
        SELECT_SIZE_ENDIAN(size, false));

  if (sym == NULL)
    return NULL;

  sym->init(name, od, value, symsize, type, binding, visibility, nonvis,
            offset_is_from_end);

  return sym;
}

// Define a symbol based on an Output_segment.

Symbol*
Symbol_table::define_in_output_segment(const Target* target, const char* name,
                                       const char* version, Output_segment* os,
                                       uint64_t value, uint64_t symsize,
                                       elfcpp::STT type, elfcpp::STB binding,
                                       elfcpp::STV visibility,
                                       unsigned char nonvis,
                                       Symbol::Segment_offset_base offset_base,
                                       bool only_if_ref)
{
  gold_assert(target->get_size() == this->size_);
  if (this->size_ == 32)
    return this->do_define_in_output_segment<32>(target, name, version, os,
                                                 value, symsize, type, binding,
                                                 visibility, nonvis,
                                                 offset_base, only_if_ref);
  else if (this->size_ == 64)
    return this->do_define_in_output_segment<64>(target, name, version, os,
                                                 value, symsize, type, binding,
                                                 visibility, nonvis,
                                                 offset_base, only_if_ref);
  else
    gold_unreachable();
}

// Define a symbol in an Output_segment, sized version.

template<int size>
Sized_symbol<size>*
Symbol_table::do_define_in_output_segment(
    const Target* target,
    const char* name,
    const char* version,
    Output_segment* os,
    typename elfcpp::Elf_types<size>::Elf_Addr value,
    typename elfcpp::Elf_types<size>::Elf_WXword symsize,
    elfcpp::STT type,
    elfcpp::STB binding,
    elfcpp::STV visibility,
    unsigned char nonvis,
    Symbol::Segment_offset_base offset_base,
    bool only_if_ref)
{
  Sized_symbol<size>* sym;

  if (target->is_big_endian())
    sym = this->define_special_symbol SELECT_SIZE_ENDIAN_NAME(size, true) (
        target, name, version, only_if_ref
        SELECT_SIZE_ENDIAN(size, true));
  else
    sym = this->define_special_symbol SELECT_SIZE_ENDIAN_NAME(size, false) (
        target, name, version, only_if_ref
        SELECT_SIZE_ENDIAN(size, false));

  if (sym == NULL)
    return NULL;

  sym->init(name, os, value, symsize, type, binding, visibility, nonvis,
            offset_base);

  return sym;
}

// Define a special symbol with a constant value.  It is a multiple
// definition error if this symbol is already defined.

Symbol*
Symbol_table::define_as_constant(const Target* target, const char* name,
                                 const char* version, uint64_t value,
                                 uint64_t symsize, elfcpp::STT type,
                                 elfcpp::STB binding, elfcpp::STV visibility,
                                 unsigned char nonvis, bool only_if_ref)
{
  gold_assert(target->get_size() == this->size_);
  if (this->size_ == 32)
    return this->do_define_as_constant<32>(target, name, version, value,
                                           symsize, type, binding, visibility,
                                           nonvis, only_if_ref);
  else if (this->size_ == 64)
    return this->do_define_as_constant<64>(target, name, version, value,
                                           symsize, type, binding, visibility,
                                           nonvis, only_if_ref);
  else
    gold_unreachable();
}

// Define a symbol as a constant, sized version.

template<int size>
Sized_symbol<size>*
Symbol_table::do_define_as_constant(
    const Target* target,
    const char* name,
    const char* version,
    typename elfcpp::Elf_types<size>::Elf_Addr value,
    typename elfcpp::Elf_types<size>::Elf_WXword symsize,
    elfcpp::STT type,
    elfcpp::STB binding,
    elfcpp::STV visibility,
    unsigned char nonvis,
    bool only_if_ref)
{
  Sized_symbol<size>* sym;

  if (target->is_big_endian())
    sym = this->define_special_symbol SELECT_SIZE_ENDIAN_NAME(size, true) (
        target, name, version, only_if_ref
        SELECT_SIZE_ENDIAN(size, true));
  else
    sym = this->define_special_symbol SELECT_SIZE_ENDIAN_NAME(size, false) (
        target, name, version, only_if_ref
        SELECT_SIZE_ENDIAN(size, false));

  if (sym == NULL)
    return NULL;

  sym->init(name, value, symsize, type, binding, visibility, nonvis);

  return sym;
}

// Define a set of symbols in output sections.

void
Symbol_table::define_symbols(const Layout* layout, const Target* target,
                             int count, const Define_symbol_in_section* p)
{
  for (int i = 0; i < count; ++i, ++p)
    {
      Output_section* os = layout->find_output_section(p->output_section);
      if (os != NULL)
        this->define_in_output_data(target, p->name, NULL, os, p->value,
                                    p->size, p->type, p->binding,
                                    p->visibility, p->nonvis,
                                    p->offset_is_from_end, p->only_if_ref);
      else
        this->define_as_constant(target, p->name, NULL, 0, p->size, p->type,
                                 p->binding, p->visibility, p->nonvis,
                                 p->only_if_ref);
    }
}

// Define a set of symbols in output segments.

void
Symbol_table::define_symbols(const Layout* layout, const Target* target,
                             int count, const Define_symbol_in_segment* p)
{
  for (int i = 0; i < count; ++i, ++p)
    {
      Output_segment* os = layout->find_output_segment(p->segment_type,
                                                       p->segment_flags_set,
                                                       p->segment_flags_clear);
      if (os != NULL)
        this->define_in_output_segment(target, p->name, NULL, os, p->value,
                                       p->size, p->type, p->binding,
                                       p->visibility, p->nonvis,
                                       p->offset_base, p->only_if_ref);
      else
        this->define_as_constant(target, p->name, NULL, 0, p->size, p->type,
                                 p->binding, p->visibility, p->nonvis,
                                 p->only_if_ref);
    }
}

// Set the dynamic symbol indexes.  INDEX is the index of the first
// global dynamic symbol.  Pointers to the symbols are stored into the
// vector SYMS.  The names are added to DYNPOOL.  This returns an
// updated dynamic symbol index.

unsigned int
Symbol_table::set_dynsym_indexes(const General_options* options,
                                 const Target* target,
                                 unsigned int index,
                                 std::vector<Symbol*>* syms,
                                 Stringpool* dynpool,
                                 Versions* versions)
{
  for (Symbol_table_type::iterator p = this->table_.begin();
       p != this->table_.end();
       ++p)
    {
      Symbol* sym = p->second;

      // Note that SYM may already have a dynamic symbol index, since
      // some symbols appear more than once in the symbol table, with
      // and without a version.

      if (!sym->needs_dynsym_entry()
          && (!options->export_dynamic()
              || !sym->in_reg()
              || !sym->is_externally_visible()))
        sym->set_dynsym_index(-1U);
      else if (!sym->has_dynsym_index())
        {
          sym->set_dynsym_index(index);
          ++index;
          syms->push_back(sym);
          dynpool->add(sym->name(), NULL);

          // Record any version information.
          if (sym->version() != NULL)
            versions->record_version(options, dynpool, sym);
        }
    }

  // Finish up the versions.  In some cases this may add new dynamic
  // symbols.
  index = versions->finalize(target, this, index, syms);

  return index;
}

// Set the final values for all the symbols.  The index of the first
// global symbol in the output file is INDEX.  Record the file offset
// OFF.  Add their names to POOL.  Return the new file offset.

off_t
Symbol_table::finalize(unsigned int index, off_t off, off_t dynoff,
                       size_t dyn_global_index, size_t dyncount,
                       Stringpool* pool)
{
  off_t ret;

  gold_assert(index != 0);
  this->first_global_index_ = index;

  this->dynamic_offset_ = dynoff;
  this->first_dynamic_global_index_ = dyn_global_index;
  this->dynamic_count_ = dyncount;

  if (this->size_ == 32)
    ret = this->sized_finalize<32>(index, off, pool);
  else if (this->size_ == 64)
    ret = this->sized_finalize<64>(index, off, pool);
  else
    gold_unreachable();

  // Now that we have the final symbol table, we can reliably note
  // which symbols should get warnings.
  this->warnings_.note_warnings(this);

  return ret;
}

// Set the final value for all the symbols.  This is called after
// Layout::finalize, so all the output sections have their final
// address.

template<int size>
off_t
Symbol_table::sized_finalize(unsigned index, off_t off, Stringpool* pool)
{
  off = align_address(off, size >> 3);
  this->offset_ = off;

  size_t orig_index = index;

  const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
  for (Symbol_table_type::iterator p = this->table_.begin();
       p != this->table_.end();
       ++p)
    {
      Sized_symbol<size>* sym = static_cast<Sized_symbol<size>*>(p->second);

      // FIXME: Here we need to decide which symbols should go into
      // the output file, based on --strip.

      // The default version of a symbol may appear twice in the
      // symbol table.  We only need to finalize it once.
      if (sym->has_symtab_index())
        continue;

      if (!sym->in_reg())
        {
          gold_assert(!sym->has_symtab_index());
          sym->set_symtab_index(-1U);
          gold_assert(sym->dynsym_index() == -1U);
          continue;
        }

      typename Sized_symbol<size>::Value_type value;

      switch (sym->source())
        {
        case Symbol::FROM_OBJECT:
          {
            unsigned int shndx = sym->shndx();

            // FIXME: We need some target specific support here.
            if (shndx >= elfcpp::SHN_LORESERVE
                && shndx != elfcpp::SHN_ABS)
              {
                fprintf(stderr, _("%s: %s: unsupported symbol section 0x%x\n"),
                        program_name, sym->name(), shndx);
                gold_exit(false);
              }

            Object* symobj = sym->object();
            if (symobj->is_dynamic())
              {
                value = 0;
                shndx = elfcpp::SHN_UNDEF;
              }
            else if (shndx == elfcpp::SHN_UNDEF)
              value = 0;
            else if (shndx == elfcpp::SHN_ABS)
              value = sym->value();
            else
              {
                Relobj* relobj = static_cast<Relobj*>(symobj);
                off_t secoff;
                Output_section* os = relobj->output_section(shndx, &secoff);

                if (os == NULL)
                  {
                    sym->set_symtab_index(-1U);
                    gold_assert(sym->dynsym_index() == -1U);
                    continue;
                  }

                value = sym->value() + os->address() + secoff;
              }
          }
          break;

        case Symbol::IN_OUTPUT_DATA:
          {
            Output_data* od = sym->output_data();
            value = sym->value() + od->address();
            if (sym->offset_is_from_end())
              value += od->data_size();
          }
          break;

        case Symbol::IN_OUTPUT_SEGMENT:
          {
            Output_segment* os = sym->output_segment();
            value = sym->value() + os->vaddr();
            switch (sym->offset_base())
              {
              case Symbol::SEGMENT_START:
                break;
              case Symbol::SEGMENT_END:
                value += os->memsz();
                break;
              case Symbol::SEGMENT_BSS:
                value += os->filesz();
                break;
              default:
                gold_unreachable();
              }
          }
          break;

        case Symbol::CONSTANT:
          value = sym->value();
          break;

        default:
          gold_unreachable();
        }

      sym->set_value(value);
      sym->set_symtab_index(index);
      pool->add(sym->name(), NULL);
      ++index;
      off += sym_size;
    }

  this->output_count_ = index - orig_index;

  return off;
}

// Write out the global symbols.

void
Symbol_table::write_globals(const Target* target, const Stringpool* sympool,
                            const Stringpool* dynpool, Output_file* of) const
{
  if (this->size_ == 32)
    {
      if (target->is_big_endian())
        this->sized_write_globals<32, true>(target, sympool, dynpool, of);
      else
        this->sized_write_globals<32, false>(target, sympool, dynpool, of);
    }
  else if (this->size_ == 64)
    {
      if (target->is_big_endian())
        this->sized_write_globals<64, true>(target, sympool, dynpool, of);
      else
        this->sized_write_globals<64, false>(target, sympool, dynpool, of);
    }
  else
    gold_unreachable();
}

// Write out the global symbols.

template<int size, bool big_endian>
void
Symbol_table::sized_write_globals(const Target*,
                                  const Stringpool* sympool,
                                  const Stringpool* dynpool,
                                  Output_file* of) const
{
  const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
  unsigned int index = this->first_global_index_;
  const off_t oview_size = this->output_count_ * sym_size;
  unsigned char* const psyms = of->get_output_view(this->offset_, oview_size);

  unsigned int dynamic_count = this->dynamic_count_;
  off_t dynamic_size = dynamic_count * sym_size;
  unsigned int first_dynamic_global_index = this->first_dynamic_global_index_;
  unsigned char* dynamic_view;
  if (this->dynamic_offset_ == 0)
    dynamic_view = NULL;
  else
    dynamic_view = of->get_output_view(this->dynamic_offset_, dynamic_size);

  unsigned char* ps = psyms;
  for (Symbol_table_type::const_iterator p = this->table_.begin();
       p != this->table_.end();
       ++p)
    {
      Sized_symbol<size>* sym = static_cast<Sized_symbol<size>*>(p->second);

      unsigned int sym_index = sym->symtab_index();
      unsigned int dynsym_index;
      if (dynamic_view == NULL)
        dynsym_index = -1U;
      else
        dynsym_index = sym->dynsym_index();

      if (sym_index == -1U && dynsym_index == -1U)
        {
          // This symbol is not included in the output file.
          continue;
        }

      if (sym_index == index)
        ++index;
      else if (sym_index != -1U)
        {
          // We have already seen this symbol, because it has a
          // default version.
          gold_assert(sym_index < index);
          if (dynsym_index == -1U)
            continue;
          sym_index = -1U;
        }

      unsigned int shndx;
      switch (sym->source())
        {
        case Symbol::FROM_OBJECT:
          {
            unsigned int in_shndx = sym->shndx();

            // FIXME: We need some target specific support here.
            if (in_shndx >= elfcpp::SHN_LORESERVE
                && in_shndx != elfcpp::SHN_ABS)
              {
                fprintf(stderr, _("%s: %s: unsupported symbol section 0x%x\n"),
                        program_name, sym->name(), in_shndx);
                gold_exit(false);
              }

            Object* symobj = sym->object();
            if (symobj->is_dynamic())
              {
                // FIXME.
                shndx = elfcpp::SHN_UNDEF;
              }
            else if (in_shndx == elfcpp::SHN_UNDEF
                     || in_shndx == elfcpp::SHN_ABS)
              shndx = in_shndx;
            else
              {
                Relobj* relobj = static_cast<Relobj*>(symobj);
                off_t secoff;
                Output_section* os = relobj->output_section(in_shndx, &secoff);
                gold_assert(os != NULL);
                shndx = os->out_shndx();
              }
          }
          break;

        case Symbol::IN_OUTPUT_DATA:
          shndx = sym->output_data()->out_shndx();
          break;

        case Symbol::IN_OUTPUT_SEGMENT:
          shndx = elfcpp::SHN_ABS;
          break;

        case Symbol::CONSTANT:
          shndx = elfcpp::SHN_ABS;
          break;

        default:
          gold_unreachable();
        }

      if (sym_index != -1U)
        {
          this->sized_write_symbol SELECT_SIZE_ENDIAN_NAME(size, big_endian) (
              sym, shndx, sympool, ps
              SELECT_SIZE_ENDIAN(size, big_endian));
          ps += sym_size;
        }

      if (dynsym_index != -1U)
        {
          dynsym_index -= first_dynamic_global_index;
          gold_assert(dynsym_index < dynamic_count);
          unsigned char* pd = dynamic_view + (dynsym_index * sym_size);
          this->sized_write_symbol SELECT_SIZE_ENDIAN_NAME(size, big_endian) (
              sym, shndx, dynpool, pd
              SELECT_SIZE_ENDIAN(size, big_endian));
        }
    }

  gold_assert(ps - psyms == oview_size);

  of->write_output_view(this->offset_, oview_size, psyms);
  if (dynamic_view != NULL)
    of->write_output_view(this->dynamic_offset_, dynamic_size, dynamic_view);
}

// Write out the symbol SYM, in section SHNDX, to P.  POOL is the
// strtab holding the name.

template<int size, bool big_endian>
void
Symbol_table::sized_write_symbol(Sized_symbol<size>* sym,
                                 unsigned int shndx,
                                 const Stringpool* pool,
                                 unsigned char* p
                                 ACCEPT_SIZE_ENDIAN) const
{
  elfcpp::Sym_write<size, big_endian> osym(p);
  osym.put_st_name(pool->get_offset(sym->name()));
  osym.put_st_value(sym->value());
  osym.put_st_size(sym->symsize());
  osym.put_st_info(elfcpp::elf_st_info(sym->binding(), sym->type()));
  osym.put_st_other(elfcpp::elf_st_other(sym->visibility(), sym->nonvis()));
  osym.put_st_shndx(shndx);
}

// Write out a section symbol.  Return the update offset.

void
Symbol_table::write_section_symbol(const Target* target,
                                   const Output_section *os,
                                   Output_file* of,
                                   off_t offset) const
{
  if (this->size_ == 32)
    {
      if (target->is_big_endian())
        this->sized_write_section_symbol<32, true>(os, of, offset);
      else
        this->sized_write_section_symbol<32, false>(os, of, offset);
    }
  else if (this->size_ == 64)
    {
      if (target->is_big_endian())
        this->sized_write_section_symbol<64, true>(os, of, offset);
      else
        this->sized_write_section_symbol<64, false>(os, of, offset);
    }
  else
    gold_unreachable();
}

// Write out a section symbol, specialized for size and endianness.

template<int size, bool big_endian>
void
Symbol_table::sized_write_section_symbol(const Output_section* os,
                                         Output_file* of,
                                         off_t offset) const
{
  const int sym_size = elfcpp::Elf_sizes<size>::sym_size;

  unsigned char* pov = of->get_output_view(offset, sym_size);

  elfcpp::Sym_write<size, big_endian> osym(pov);
  osym.put_st_name(0);
  osym.put_st_value(os->address());
  osym.put_st_size(0);
  osym.put_st_info(elfcpp::elf_st_info(elfcpp::STB_LOCAL,
                                       elfcpp::STT_SECTION));
  osym.put_st_other(elfcpp::elf_st_other(elfcpp::STV_DEFAULT, 0));
  osym.put_st_shndx(os->out_shndx());

  of->write_output_view(offset, sym_size, pov);
}

// Warnings functions.

// Add a new warning.

void
Warnings::add_warning(Symbol_table* symtab, const char* name, Object* obj,
                      unsigned int shndx)
{
  name = symtab->canonicalize_name(name);
  this->warnings_[name].set(obj, shndx);
}

// Look through the warnings and mark the symbols for which we should
// warn.  This is called during Layout::finalize when we know the
// sources for all the symbols.

void
Warnings::note_warnings(Symbol_table* symtab)
{
  for (Warning_table::iterator p = this->warnings_.begin();
       p != this->warnings_.end();
       ++p)
    {
      Symbol* sym = symtab->lookup(p->first, NULL);
      if (sym != NULL
          && sym->source() == Symbol::FROM_OBJECT
          && sym->object() == p->second.object)
        {
          sym->set_has_warning();

          // Read the section contents to get the warning text.  It
          // would be nicer if we only did this if we have to actually
          // issue a warning.  Unfortunately, warnings are issued as
          // we relocate sections.  That means that we can not lock
          // the object then, as we might try to issue the same
          // warning multiple times simultaneously.
          {
            Task_locker_obj<Object> tl(*p->second.object);
            const unsigned char* c;
            off_t len;
            c = p->second.object->section_contents(p->second.shndx, &len);
            p->second.set_text(reinterpret_cast<const char*>(c), len);
          }
        }
    }
}

// Issue a warning.  This is called when we see a relocation against a
// symbol for which has a warning.

void
Warnings::issue_warning(const Symbol* sym, const std::string& location) const
{
  gold_assert(sym->has_warning());
  Warning_table::const_iterator p = this->warnings_.find(sym->name());
  gold_assert(p != this->warnings_.end());
  fprintf(stderr, _("%s: %s: warning: %s\n"), program_name, location.c_str(),
          p->second.text.c_str());
}

// Instantiate the templates we need.  We could use the configure
// script to restrict this to only the ones needed for implemented
// targets.

template
void
Symbol_table::add_from_relobj<32, true>(
    Sized_relobj<32, true>* relobj,
    const unsigned char* syms,
    size_t count,
    const char* sym_names,
    size_t sym_name_size,
    Symbol** sympointers);

template
void
Symbol_table::add_from_relobj<32, false>(
    Sized_relobj<32, false>* relobj,
    const unsigned char* syms,
    size_t count,
    const char* sym_names,
    size_t sym_name_size,
    Symbol** sympointers);

template
void
Symbol_table::add_from_relobj<64, true>(
    Sized_relobj<64, true>* relobj,
    const unsigned char* syms,
    size_t count,
    const char* sym_names,
    size_t sym_name_size,
    Symbol** sympointers);

template
void
Symbol_table::add_from_relobj<64, false>(
    Sized_relobj<64, false>* relobj,
    const unsigned char* syms,
    size_t count,
    const char* sym_names,
    size_t sym_name_size,
    Symbol** sympointers);

template
void
Symbol_table::add_from_dynobj<32, true>(
    Sized_dynobj<32, true>* dynobj,
    const unsigned char* syms,
    size_t count,
    const char* sym_names,
    size_t sym_name_size,
    const unsigned char* versym,
    size_t versym_size,
    const std::vector<const char*>* version_map);

template
void
Symbol_table::add_from_dynobj<32, false>(
    Sized_dynobj<32, false>* dynobj,
    const unsigned char* syms,
    size_t count,
    const char* sym_names,
    size_t sym_name_size,
    const unsigned char* versym,
    size_t versym_size,
    const std::vector<const char*>* version_map);

template
void
Symbol_table::add_from_dynobj<64, true>(
    Sized_dynobj<64, true>* dynobj,
    const unsigned char* syms,
    size_t count,
    const char* sym_names,
    size_t sym_name_size,
    const unsigned char* versym,
    size_t versym_size,
    const std::vector<const char*>* version_map);

template
void
Symbol_table::add_from_dynobj<64, false>(
    Sized_dynobj<64, false>* dynobj,
    const unsigned char* syms,
    size_t count,
    const char* sym_names,
    size_t sym_name_size,
    const unsigned char* versym,
    size_t versym_size,
    const std::vector<const char*>* version_map);

} // End namespace gold.