linker.c

基于4个mips核的noc设计

   This linked list is used to hold the elements.  */

struct archive_list
{
  struct archive_list *next;
  int indx;
};

/* An entry in an archive hash table.  */

struct archive_hash_entry
{
  struct bfd_hash_entry root;
  /* Where the symbol is defined.  */
  struct archive_list *defs;
};

/* An archive hash table itself.  */

struct archive_hash_table
{
  struct bfd_hash_table table;
};

static struct bfd_hash_entry *archive_hash_newfunc
  PARAMS ((struct bfd_hash_entry *, struct bfd_hash_table *, const char *));
static boolean archive_hash_table_init
  PARAMS ((struct archive_hash_table *,
	   struct bfd_hash_entry *(*) (struct bfd_hash_entry *,
				       struct bfd_hash_table *,
				       const char *)));

/* Create a new entry for an archive hash table.  */

static struct bfd_hash_entry *
archive_hash_newfunc (entry, table, string)
     struct bfd_hash_entry *entry;
     struct bfd_hash_table *table;
     const char *string;
{
  struct archive_hash_entry *ret = (struct archive_hash_entry *) entry;

  /* Allocate the structure if it has not already been allocated by a
     subclass.  */
  if (ret == (struct archive_hash_entry *) NULL)
    ret = ((struct archive_hash_entry *)
	   bfd_hash_allocate (table, sizeof (struct archive_hash_entry)));
  if (ret == (struct archive_hash_entry *) NULL)
    return NULL;

  /* Call the allocation method of the superclass.  */
  ret = ((struct archive_hash_entry *)
	 bfd_hash_newfunc ((struct bfd_hash_entry *) ret, table, string));

  if (ret)
    {
      /* Initialize the local fields.  */
      ret->defs = (struct archive_list *) NULL;
    }

  return (struct bfd_hash_entry *) ret;
}

/* Initialize an archive hash table.  */

static boolean
archive_hash_table_init (table, newfunc)
     struct archive_hash_table *table;
     struct bfd_hash_entry *(*newfunc) PARAMS ((struct bfd_hash_entry *,
						struct bfd_hash_table *,
						const char *));
{
  return bfd_hash_table_init (&table->table, newfunc);
}

/* Look up an entry in an archive hash table.  */

#define archive_hash_lookup(t, string, create, copy) \
  ((struct archive_hash_entry *) \
   bfd_hash_lookup (&(t)->table, (string), (create), (copy)))

/* Allocate space in an archive hash table.  */

#define archive_hash_allocate(t, size) bfd_hash_allocate (&(t)->table, (size))

/* Free an archive hash table.  */

#define archive_hash_table_free(t) bfd_hash_table_free (&(t)->table)

/* Generic function to add symbols from an archive file to the global
   hash file.  This function presumes that the archive symbol table
   has already been read in (this is normally done by the
   bfd_check_format entry point).  It looks through the undefined and
   common symbols and searches the archive symbol table for them.  If
   it finds an entry, it includes the associated object file in the
   link.

   The old linker looked through the archive symbol table for
   undefined symbols.  We do it the other way around, looking through
   undefined symbols for symbols defined in the archive.  The
   advantage of the newer scheme is that we only have to look through
   the list of undefined symbols once, whereas the old method had to
   re-search the symbol table each time a new object file was added.

   The CHECKFN argument is used to see if an object file should be
   included.  CHECKFN should set *PNEEDED to true if the object file
   should be included, and must also call the bfd_link_info
   add_archive_element callback function and handle adding the symbols
   to the global hash table.  CHECKFN should only return false if some
   sort of error occurs.

   For some formats, such as a.out, it is possible to look through an
   object file but not actually include it in the link.  The
   archive_pass field in a BFD is used to avoid checking the symbols
   of an object files too many times.  When an object is included in
   the link, archive_pass is set to -1.  If an object is scanned but
   not included, archive_pass is set to the pass number.  The pass
   number is incremented each time a new object file is included.  The
   pass number is used because when a new object file is included it
   may create new undefined symbols which cause a previously examined
   object file to be included.  */

boolean
_bfd_generic_link_add_archive_symbols (abfd, info, checkfn)
     bfd *abfd;
     struct bfd_link_info *info;
     boolean (*checkfn) PARAMS ((bfd *, struct bfd_link_info *,
				 boolean *pneeded));
{
  carsym *arsyms;
  carsym *arsym_end;
  register carsym *arsym;
  int pass;
  struct archive_hash_table arsym_hash;
  int indx;
  struct bfd_link_hash_entry **pundef;

  if (! bfd_has_map (abfd))
    {
      /* An empty archive is a special case.  */
      if (bfd_openr_next_archived_file (abfd, (bfd *) NULL) == NULL)
	return true;
      bfd_set_error (bfd_error_no_armap);
      return false;
    }

  arsyms = bfd_ardata (abfd)->symdefs;
  arsym_end = arsyms + bfd_ardata (abfd)->symdef_count;

  /* In order to quickly determine whether an symbol is defined in
     this archive, we build a hash table of the symbols.  */
  if (! archive_hash_table_init (&arsym_hash, archive_hash_newfunc))
    return false;
  for (arsym = arsyms, indx = 0; arsym < arsym_end; arsym++, indx++)
    {
      struct archive_hash_entry *arh;
      struct archive_list *l, **pp;

      arh = archive_hash_lookup (&arsym_hash, arsym->name, true, false);
      if (arh == (struct archive_hash_entry *) NULL)
	goto error_return;
      l = ((struct archive_list *)
	   archive_hash_allocate (&arsym_hash, sizeof (struct archive_list)));
      if (l == NULL)
	goto error_return;
      l->indx = indx;
      for (pp = &arh->defs;
	   *pp != (struct archive_list *) NULL;
	   pp = &(*pp)->next)
	;
      *pp = l;
      l->next = NULL;
    }

  /* The archive_pass field in the archive itself is used to
     initialize PASS, sine we may search the same archive multiple
     times.  */
  pass = abfd->archive_pass + 1;

  /* New undefined symbols are added to the end of the list, so we
     only need to look through it once.  */
  pundef = &info->hash->undefs;
  while (*pundef != (struct bfd_link_hash_entry *) NULL)
    {
      struct bfd_link_hash_entry *h;
      struct archive_hash_entry *arh;
      struct archive_list *l;

      h = *pundef;

      /* When a symbol is defined, it is not necessarily removed from
	 the list.  */
      if (h->type != bfd_link_hash_undefined
	  && h->type != bfd_link_hash_common)
	{
	  /* Remove this entry from the list, for general cleanliness
	     and because we are going to look through the list again
	     if we search any more libraries.  We can't remove the
	     entry if it is the tail, because that would lose any
	     entries we add to the list later on (it would also cause
	     us to lose track of whether the symbol has been
	     referenced).  */
	  if (*pundef != info->hash->undefs_tail)
	    *pundef = (*pundef)->next;
	  else
	    pundef = &(*pundef)->next;
	  continue;
	}

      /* Look for this symbol in the archive symbol map.  */
      arh = archive_hash_lookup (&arsym_hash, h->root.string, false, false);
      if (arh == (struct archive_hash_entry *) NULL)
	{
	  pundef = &(*pundef)->next;
	  continue;
	}

      /* Look at all the objects which define this symbol.  */
      for (l = arh->defs; l != (struct archive_list *) NULL; l = l->next)
	{
	  bfd *element;
	  boolean needed;

	  /* If the symbol has gotten defined along the way, quit.  */
	  if (h->type != bfd_link_hash_undefined
	      && h->type != bfd_link_hash_common)
	    break;

	  element = bfd_get_elt_at_index (abfd, l->indx);
	  if (element == (bfd *) NULL)
	    goto error_return;

	  /* If we've already included this element, or if we've
	     already checked it on this pass, continue.  */
	  if (element->archive_pass == -1
	      || element->archive_pass == pass)
	    continue;

	  /* If we can't figure this element out, just ignore it.  */
	  if (! bfd_check_format (element, bfd_object))
	    {
	      element->archive_pass = -1;
	      continue;
	    }

	  /* CHECKFN will see if this element should be included, and
	     go ahead and include it if appropriate.  */
	  if (! (*checkfn) (element, info, &needed))
	    goto error_return;

	  if (! needed)
	    element->archive_pass = pass;
	  else
	    {
	      element->archive_pass = -1;

	      /* Increment the pass count to show that we may need to
		 recheck object files which were already checked.  */
	      ++pass;
	    }
	}

      pundef = &(*pundef)->next;
    }

  archive_hash_table_free (&arsym_hash);

  /* Save PASS in case we are called again.  */
  abfd->archive_pass = pass;

  return true;

 error_return:
  archive_hash_table_free (&arsym_hash);
  return false;
}

/* See if we should include an archive element.  This version is used
   when we do not want to automatically collect constructors based on
   the symbol name, presumably because we have some other mechanism
   for finding them.  */

static boolean
generic_link_check_archive_element_no_collect (abfd, info, pneeded)
     bfd *abfd;
     struct bfd_link_info *info;
     boolean *pneeded;
{
  return generic_link_check_archive_element (abfd, info, pneeded, false);
}

/* See if we should include an archive element.  This version is used
   when we want to automatically collect constructors based on the
   symbol name, as collect2 does.  */

static boolean
generic_link_check_archive_element_collect (abfd, info, pneeded)
     bfd *abfd;
     struct bfd_link_info *info;
     boolean *pneeded;
{
  return generic_link_check_archive_element (abfd, info, pneeded, true);
}

/* See if we should include an archive element.  Optionally collect
   constructors.  */

static boolean
generic_link_check_archive_element (abfd, info, pneeded, collect)
     bfd *abfd;
     struct bfd_link_info *info;
     boolean *pneeded;
     boolean collect;
{
  asymbol **pp, **ppend;

  *pneeded = false;

  if (! generic_link_read_symbols (abfd))
    return false;

  pp = _bfd_generic_link_get_symbols (abfd);
  ppend = pp + _bfd_generic_link_get_symcount (abfd);
  for (; pp < ppend; pp++)
    {
      asymbol *p;
      struct bfd_link_hash_entry *h;

      p = *pp;

      /* We are only interested in globally visible symbols.  */
      if (! bfd_is_com_section (p->section)
	  && (p->flags & (BSF_GLOBAL | BSF_INDIRECT | BSF_WEAK)) == 0)
	continue;

      /* We are only interested if we know something about this
	 symbol, and it is undefined or common.  An undefined weak
	 symbol (type bfd_link_hash_undefweak) is not considered to be
	 a reference when pulling files out of an archive.  See the
	 SVR4 ABI, p. 4-27.  */
      h = bfd_link_hash_lookup (info->hash, bfd_asymbol_name (p), false,
				false, true);
      if (h == (struct bfd_link_hash_entry *) NULL
	  || (h->type != bfd_link_hash_undefined
	      && h->type != bfd_link_hash_common))
	continue;

      /* P is a symbol we are looking for.  */

      if (! bfd_is_com_section (p->section))
	{
	  bfd_size_type symcount;
	  asymbol **symbols;

	  /* This object file defines this symbol, so pull it in.  */
	  if (! (*info->callbacks->add_archive_element) (info, abfd,
							 bfd_asymbol_name (p)))
	    return false;
	  symcount = _bfd_generic_link_get_symcount (abfd);
	  symbols = _bfd_generic_link_get_symbols (abfd);
	  if (! generic_link_add_symbol_list (abfd, info, symcount,
					      symbols, collect))
	    return false;
	  *pneeded = true;
	  return true;
	}

      /* P is a common symbol.  */

      if (h->type == bfd_link_hash_undefined)
	{
	  bfd *symbfd;
	  bfd_vma size;
	  unsigned int power;

	  symbfd = h->u.undef.abfd;
	  if (symbfd == (bfd *) NULL)
	    {
	      /* This symbol was created as undefined from outside
		 BFD.  We assume that we should link in the object
		 file.  This is for the -u option in the linker.  */
	      if (! (*info->callbacks->add_archive_element)
		  (info, abfd, bfd_asymbol_name (p)))
		return false;
	      *pneeded = true;
	      return true;
	    }

	  /* Turn the symbol into a common symbol but do not link in
	     the object file.  This is how a.out works.  Object
	     formats that require different semantics must implement
	     this function differently.  This symbol is already on the
	     undefs list.  We add the section to a common section
	     attached to symbfd to ensure that it is in a BFD which
	     will be linked in.  */
	  h->type = bfd_link_hash_common;