Subversion Repositories openrisc_2011-10-31

/* linker.c -- BFD linker routines

   Copyright 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002,

   2003, 2004, 2005, 2006, 2007, 2008, 2009

   Free Software Foundation, Inc.

   Written by Steve Chamberlain and Ian Lance Taylor, Cygnus Support

   This file is part of BFD, the Binary File Descriptor library.

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program; if not, write to the Free Software

   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,

   MA 02110-1301, USA.  */

#include "sysdep.h"

#include "bfd.h"

#include "libbfd.h"

#include "bfdlink.h"

#include "genlink.h"

/*

SECTION

        Linker Functions

@cindex Linker

        The linker uses three special entry points in the BFD target

        vector.  It is not necessary to write special routines for

        these entry points when creating a new BFD back end, since

        generic versions are provided.  However, writing them can

        speed up linking and make it use significantly less runtime

        memory.

        The first routine creates a hash table used by the other

        routines.  The second routine adds the symbols from an object

        file to the hash table.  The third routine takes all the

        object files and links them together to create the output

        file.  These routines are designed so that the linker proper

        does not need to know anything about the symbols in the object

        files that it is linking.  The linker merely arranges the

        sections as directed by the linker script and lets BFD handle

        the details of symbols and relocs.

        The second routine and third routines are passed a pointer to

        a <<struct bfd_link_info>> structure (defined in

        <<bfdlink.h>>) which holds information relevant to the link,

        including the linker hash table (which was created by the

        first routine) and a set of callback functions to the linker

        proper.

        The generic linker routines are in <<linker.c>>, and use the

        header file <<genlink.h>>.  As of this writing, the only back

        ends which have implemented versions of these routines are

        a.out (in <<aoutx.h>>) and ECOFF (in <<ecoff.c>>).  The a.out

        routines are used as examples throughout this section.

@menu

@* Creating a Linker Hash Table::

@* Adding Symbols to the Hash Table::

@* Performing the Final Link::

@end menu

INODE

Creating a Linker Hash Table, Adding Symbols to the Hash Table, Linker Functions, Linker Functions

SUBSECTION

        Creating a linker hash table

@cindex _bfd_link_hash_table_create in target vector

@cindex target vector (_bfd_link_hash_table_create)

        The linker routines must create a hash table, which must be

        derived from <<struct bfd_link_hash_table>> described in

        <<bfdlink.c>>.  @xref{Hash Tables}, for information on how to

        create a derived hash table.  This entry point is called using

        the target vector of the linker output file.

        The <<_bfd_link_hash_table_create>> entry point must allocate

        and initialize an instance of the desired hash table.  If the

        back end does not require any additional information to be

        stored with the entries in the hash table, the entry point may

        simply create a <<struct bfd_link_hash_table>>.  Most likely,

        however, some additional information will be needed.

        For example, with each entry in the hash table the a.out

        linker keeps the index the symbol has in the final output file

        (this index number is used so that when doing a relocatable

        link the symbol index used in the output file can be quickly

        filled in when copying over a reloc).  The a.out linker code

        defines the required structures and functions for a hash table

        derived from <<struct bfd_link_hash_table>>.  The a.out linker

        hash table is created by the function

        <<NAME(aout,link_hash_table_create)>>; it simply allocates

        space for the hash table, initializes it, and returns a

        pointer to it.

        When writing the linker routines for a new back end, you will

        generally not know exactly which fields will be required until

        you have finished.  You should simply create a new hash table

        which defines no additional fields, and then simply add fields

        as they become necessary.

INODE

Adding Symbols to the Hash Table, Performing the Final Link, Creating a Linker Hash Table, Linker Functions

SUBSECTION

        Adding symbols to the hash table

@cindex _bfd_link_add_symbols in target vector

@cindex target vector (_bfd_link_add_symbols)

        The linker proper will call the <<_bfd_link_add_symbols>>

        entry point for each object file or archive which is to be

        linked (typically these are the files named on the command

        line, but some may also come from the linker script).  The

        entry point is responsible for examining the file.  For an

        object file, BFD must add any relevant symbol information to

        the hash table.  For an archive, BFD must determine which

        elements of the archive should be used and adding them to the

        link.

        The a.out version of this entry point is

        <<NAME(aout,link_add_symbols)>>.

@menu

@* Differing file formats::

@* Adding symbols from an object file::

@* Adding symbols from an archive::

@end menu

INODE

Differing file formats, Adding symbols from an object file, Adding Symbols to the Hash Table, Adding Symbols to the Hash Table

SUBSUBSECTION

        Differing file formats

        Normally all the files involved in a link will be of the same

        format, but it is also possible to link together different

        format object files, and the back end must support that.  The

        <<_bfd_link_add_symbols>> entry point is called via the target

        vector of the file to be added.  This has an important

        consequence: the function may not assume that the hash table

        is the type created by the corresponding

        <<_bfd_link_hash_table_create>> vector.  All the

        <<_bfd_link_add_symbols>> function can assume about the hash

        table is that it is derived from <<struct

        bfd_link_hash_table>>.

        Sometimes the <<_bfd_link_add_symbols>> function must store

        some information in the hash table entry to be used by the

        <<_bfd_final_link>> function.  In such a case the output bfd

        xvec must be checked to make sure that the hash table was

        created by an object file of the same format.

        The <<_bfd_final_link>> routine must be prepared to handle a

        hash entry without any extra information added by the

        <<_bfd_link_add_symbols>> function.  A hash entry without

        extra information will also occur when the linker script

        directs the linker to create a symbol.  Note that, regardless

        of how a hash table entry is added, all the fields will be

        initialized to some sort of null value by the hash table entry

        initialization function.

        See <<ecoff_link_add_externals>> for an example of how to

        check the output bfd before saving information (in this

        case, the ECOFF external symbol debugging information) in a

        hash table entry.

INODE

Adding symbols from an object file, Adding symbols from an archive, Differing file formats, Adding Symbols to the Hash Table

SUBSUBSECTION

        Adding symbols from an object file

        When the <<_bfd_link_add_symbols>> routine is passed an object

        file, it must add all externally visible symbols in that

        object file to the hash table.  The actual work of adding the

        symbol to the hash table is normally handled by the function

        <<_bfd_generic_link_add_one_symbol>>.  The

        <<_bfd_link_add_symbols>> routine is responsible for reading

        all the symbols from the object file and passing the correct

        information to <<_bfd_generic_link_add_one_symbol>>.

        The <<_bfd_link_add_symbols>> routine should not use

        <<bfd_canonicalize_symtab>> to read the symbols.  The point of

        providing this routine is to avoid the overhead of converting

        the symbols into generic <<asymbol>> structures.

@findex _bfd_generic_link_add_one_symbol

        <<_bfd_generic_link_add_one_symbol>> handles the details of

        combining common symbols, warning about multiple definitions,

        and so forth.  It takes arguments which describe the symbol to

        add, notably symbol flags, a section, and an offset.  The

        symbol flags include such things as <<BSF_WEAK>> or

        <<BSF_INDIRECT>>.  The section is a section in the object

        file, or something like <<bfd_und_section_ptr>> for an undefined

        symbol or <<bfd_com_section_ptr>> for a common symbol.

        If the <<_bfd_final_link>> routine is also going to need to

        read the symbol information, the <<_bfd_link_add_symbols>>

        routine should save it somewhere attached to the object file

        BFD.  However, the information should only be saved if the

        <<keep_memory>> field of the <<info>> argument is TRUE, so

        that the <<-no-keep-memory>> linker switch is effective.

        The a.out function which adds symbols from an object file is

        <<aout_link_add_object_symbols>>, and most of the interesting

        work is in <<aout_link_add_symbols>>.  The latter saves

        pointers to the hash tables entries created by

        <<_bfd_generic_link_add_one_symbol>> indexed by symbol number,

        so that the <<_bfd_final_link>> routine does not have to call

        the hash table lookup routine to locate the entry.

INODE

Adding symbols from an archive, , Adding symbols from an object file, Adding Symbols to the Hash Table

SUBSUBSECTION

        Adding symbols from an archive

        When the <<_bfd_link_add_symbols>> routine is passed an

        archive, it must look through the symbols defined by the

        archive and decide which elements of the archive should be

        included in the link.  For each such element it must call the

        <<add_archive_element>> linker callback, and it must add the

        symbols from the object file to the linker hash table.

@findex _bfd_generic_link_add_archive_symbols

        In most cases the work of looking through the symbols in the

        archive should be done by the

        <<_bfd_generic_link_add_archive_symbols>> function.  This

        function builds a hash table from the archive symbol table and

        looks through the list of undefined symbols to see which

        elements should be included.

        <<_bfd_generic_link_add_archive_symbols>> is passed a function

        to call to make the final decision about adding an archive

        element to the link and to do the actual work of adding the

        symbols to the linker hash table.

        The function passed to

        <<_bfd_generic_link_add_archive_symbols>> must read the

        symbols of the archive element and decide whether the archive

        element should be included in the link.  If the element is to

        be included, the <<add_archive_element>> linker callback

        routine must be called with the element as an argument, and

        the elements symbols must be added to the linker hash table

        just as though the element had itself been passed to the

        <<_bfd_link_add_symbols>> function.

        When the a.out <<_bfd_link_add_symbols>> function receives an

        archive, it calls <<_bfd_generic_link_add_archive_symbols>>

        passing <<aout_link_check_archive_element>> as the function

        argument. <<aout_link_check_archive_element>> calls

        <<aout_link_check_ar_symbols>>.  If the latter decides to add

        the element (an element is only added if it provides a real,

        non-common, definition for a previously undefined or common

        symbol) it calls the <<add_archive_element>> callback and then

        <<aout_link_check_archive_element>> calls

        <<aout_link_add_symbols>> to actually add the symbols to the

        linker hash table.

        The ECOFF back end is unusual in that it does not normally

        call <<_bfd_generic_link_add_archive_symbols>>, because ECOFF

        archives already contain a hash table of symbols.  The ECOFF

        back end searches the archive itself to avoid the overhead of

        creating a new hash table.

INODE

Performing the Final Link, , Adding Symbols to the Hash Table, Linker Functions

SUBSECTION

        Performing the final link

@cindex _bfd_link_final_link in target vector

@cindex target vector (_bfd_final_link)

        When all the input files have been processed, the linker calls

        the <<_bfd_final_link>> entry point of the output BFD.  This

        routine is responsible for producing the final output file,

        which has several aspects.  It must relocate the contents of

        the input sections and copy the data into the output sections.

        It must build an output symbol table including any local

        symbols from the input files and the global symbols from the

        hash table.  When producing relocatable output, it must

        modify the input relocs and write them into the output file.

        There may also be object format dependent work to be done.

        The linker will also call the <<write_object_contents>> entry

        point when the BFD is closed.  The two entry points must work

        together in order to produce the correct output file.

        The details of how this works are inevitably dependent upon

        the specific object file format.  The a.out

        <<_bfd_final_link>> routine is <<NAME(aout,final_link)>>.

@menu

@* Information provided by the linker::

@* Relocating the section contents::

@* Writing the symbol table::

@end menu

INODE

Information provided by the linker, Relocating the section contents, Performing the Final Link, Performing the Final Link

SUBSUBSECTION

        Information provided by the linker

        Before the linker calls the <<_bfd_final_link>> entry point,

        it sets up some data structures for the function to use.

        The <<input_bfds>> field of the <<bfd_link_info>> structure

        will point to a list of all the input files included in the

        link.  These files are linked through the <<link_next>> field

        of the <<bfd>> structure.

        Each section in the output file will have a list of

        <<link_order>> structures attached to the <<map_head.link_order>>

        field (the <<link_order>> structure is defined in

        <<bfdlink.h>>).  These structures describe how to create the

        contents of the output section in terms of the contents of

        various input sections, fill constants, and, eventually, other

        types of information.  They also describe relocs that must be

        created by the BFD backend, but do not correspond to any input

        file; this is used to support -Ur, which builds constructors

        while generating a relocatable object file.

INODE

Relocating the section contents, Writing the symbol table, Information provided by the linker, Performing the Final Link

SUBSUBSECTION

        Relocating the section contents

        The <<_bfd_final_link>> function should look through the

        <<link_order>> structures attached to each section of the

        output file.  Each <<link_order>> structure should either be

        handled specially, or it should be passed to the function

        <<_bfd_default_link_order>> which will do the right thing

        (<<_bfd_default_link_order>> is defined in <<linker.c>>).

        For efficiency, a <<link_order>> of type

        <<bfd_indirect_link_order>> whose associated section belongs

        to a BFD of the same format as the output BFD must be handled

        specially.  This type of <<link_order>> describes part of an

        output section in terms of a section belonging to one of the

        input files.  The <<_bfd_final_link>> function should read the

        contents of the section and any associated relocs, apply the

        relocs to the section contents, and write out the modified

        section contents.  If performing a relocatable link, the

        relocs themselves must also be modified and written out.

@findex _bfd_relocate_contents

@findex _bfd_final_link_relocate

        The functions <<_bfd_relocate_contents>> and

        <<_bfd_final_link_relocate>> provide some general support for

        performing the actual relocations, notably overflow checking.

        Their arguments include information about the symbol the

        relocation is against and a <<reloc_howto_type>> argument

        which describes the relocation to perform.  These functions

        are defined in <<reloc.c>>.

        The a.out function which handles reading, relocating, and

        writing section contents is <<aout_link_input_section>>.  The

        actual relocation is done in <<aout_link_input_section_std>>

        and <<aout_link_input_section_ext>>.

INODE

Writing the symbol table, , Relocating the section contents, Performing the Final Link

SUBSUBSECTION

        Writing the symbol table

        The <<_bfd_final_link>> function must gather all the symbols

        in the input files and write them out.  It must also write out

        all the symbols in the global hash table.  This must be

        controlled by the <<strip>> and <<discard>> fields of the

        <<bfd_link_info>> structure.

        The local symbols of the input files will not have been

        entered into the linker hash table.  The <<_bfd_final_link>>

        routine must consider each input file and include the symbols

        in the output file.  It may be convenient to do this when

        looking through the <<link_order>> structures, or it may be

        done by stepping through the <<input_bfds>> list.

        The <<_bfd_final_link>> routine must also traverse the global

        hash table to gather all the externally visible symbols.  It

        is possible that most of the externally visible symbols may be

        written out when considering the symbols of each input file,

        but it is still necessary to traverse the hash table since the

        linker script may have defined some symbols that are not in

        any of the input files.

        The <<strip>> field of the <<bfd_link_info>> structure

        controls which symbols are written out.  The possible values

        are listed in <<bfdlink.h>>.  If the value is <<strip_some>>,

        then the <<keep_hash>> field of the <<bfd_link_info>>

        structure is a hash table of symbols to keep; each symbol

        should be looked up in this hash table, and only symbols which

        are present should be included in the output file.

        If the <<strip>> field of the <<bfd_link_info>> structure

        permits local symbols to be written out, the <<discard>> field

        is used to further controls which local symbols are included

        in the output file.  If the value is <<discard_l>>, then all

        local symbols which begin with a certain prefix are discarded;

        this is controlled by the <<bfd_is_local_label_name>> entry point.

        The a.out backend handles symbols by calling

        <<aout_link_write_symbols>> on each input BFD and then

        traversing the global hash table with the function

        <<aout_link_write_other_symbol>>.  It builds a string table

        while writing out the symbols, which is written to the output

        file at the end of <<NAME(aout,final_link)>>.

*/

static bfd_boolean generic_link_add_object_symbols

  (bfd *, struct bfd_link_info *, bfd_boolean collect);

static bfd_boolean generic_link_add_symbols

  (bfd *, struct bfd_link_info *, bfd_boolean);

static bfd_boolean generic_link_check_archive_element_no_collect

  (bfd *, struct bfd_link_info *, bfd_boolean *);

static bfd_boolean generic_link_check_archive_element_collect

  (bfd *, struct bfd_link_info *, bfd_boolean *);

static bfd_boolean generic_link_check_archive_element

  (bfd *, struct bfd_link_info *, bfd_boolean *, bfd_boolean);

static bfd_boolean generic_link_add_symbol_list

  (bfd *, struct bfd_link_info *, bfd_size_type count, asymbol **,

   bfd_boolean);

static bfd_boolean generic_add_output_symbol

  (bfd *, size_t *psymalloc, asymbol *);

static bfd_boolean default_data_link_order

  (bfd *, struct bfd_link_info *, asection *, struct bfd_link_order *);

static bfd_boolean default_indirect_link_order

  (bfd *, struct bfd_link_info *, asection *, struct bfd_link_order *,

   bfd_boolean);

/* The link hash table structure is defined in bfdlink.h.  It provides

   a base hash table which the backend specific hash tables are built

   upon.  */

/* Routine to create an entry in the link hash table.  */

struct bfd_hash_entry *

_bfd_link_hash_newfunc (struct bfd_hash_entry *entry,

                        struct bfd_hash_table *table,

                        const char *string)

{

  /* Allocate the structure if it has not already been allocated by a

     subclass.  */

  if (entry == NULL)

    {

      entry = (struct bfd_hash_entry *)

          bfd_hash_allocate (table, sizeof (struct bfd_link_hash_entry));

      if (entry == NULL)

        return entry;

    }

  /* Call the allocation method of the superclass.  */

  entry = bfd_hash_newfunc (entry, table, string);

  if (entry)

    {

      struct bfd_link_hash_entry *h = (struct bfd_link_hash_entry *) entry;

      /* Initialize the local fields.  */

      h->type = bfd_link_hash_new;

      memset (&h->u.undef.next, 0,

              (sizeof (struct bfd_link_hash_entry)

               - offsetof (struct bfd_link_hash_entry, u.undef.next)));

    }

  return entry;

}

/* Initialize a link hash table.  The BFD argument is the one

   responsible for creating this table.  */

bfd_boolean

_bfd_link_hash_table_init

  (struct bfd_link_hash_table *table,

   bfd *abfd ATTRIBUTE_UNUSED,

   struct bfd_hash_entry *(*newfunc) (struct bfd_hash_entry *,

                                      struct bfd_hash_table *,

                                      const char *),

   unsigned int entsize)

{

  table->undefs = NULL;

  table->undefs_tail = NULL;

  table->type = bfd_link_generic_hash_table;

  return bfd_hash_table_init (&table->table, newfunc, entsize);

}

/* Look up a symbol in a link hash table.  If follow is TRUE, we

   follow bfd_link_hash_indirect and bfd_link_hash_warning links to

   the real symbol.  */

struct bfd_link_hash_entry *

bfd_link_hash_lookup (struct bfd_link_hash_table *table,

                      const char *string,

                      bfd_boolean create,

                      bfd_boolean copy,

                      bfd_boolean follow)

{

  struct bfd_link_hash_entry *ret;

  ret = ((struct bfd_link_hash_entry *)

         bfd_hash_lookup (&table->table, string, create, copy));

  if (follow && ret != NULL)

    {

      while (ret->type == bfd_link_hash_indirect

             || ret->type == bfd_link_hash_warning)

        ret = ret->u.i.link;

    }

  return ret;

}

/* Look up a symbol in the main linker hash table if the symbol might

   be wrapped.  This should only be used for references to an

   undefined symbol, not for definitions of a symbol.  */

struct bfd_link_hash_entry *

bfd_wrapped_link_hash_lookup (bfd *abfd,

                              struct bfd_link_info *info,

                              const char *string,

                              bfd_boolean create,

                              bfd_boolean copy,

                              bfd_boolean follow)

{

  bfd_size_type amt;

  if (info->wrap_hash != NULL)

    {

      const char *l;

      char prefix = '\0';

      l = string;

      if (*l == bfd_get_symbol_leading_char (abfd) || *l == info->wrap_char)

        {

          prefix = *l;

          ++l;

        }

#undef WRAP

#define WRAP "__wrap_"

      if (bfd_hash_lookup (info->wrap_hash, l, FALSE, FALSE) != NULL)

        {

          char *n;

          struct bfd_link_hash_entry *h;

          /* This symbol is being wrapped.  We want to replace all

             references to SYM with references to __wrap_SYM.  */

          amt = strlen (l) + sizeof WRAP + 1;

          n = (char *) bfd_malloc (amt);

          if (n == NULL)

            return NULL;

          n[0] = prefix;

          n[1] = '\0';

          strcat (n, WRAP);

          strcat (n, l);

          h = bfd_link_hash_lookup (info->hash, n, create, TRUE, follow);

          free (n);

          return h;

        }

#undef WRAP

#undef  REAL

#define REAL "__real_"

      if (*l == '_'

          && CONST_STRNEQ (l, REAL)

          && bfd_hash_lookup (info->wrap_hash, l + sizeof REAL - 1,

                              FALSE, FALSE) != NULL)

        {

          char *n;

          struct bfd_link_hash_entry *h;

          /* This is a reference to __real_SYM, where SYM is being

             wrapped.  We want to replace all references to __real_SYM

             with references to SYM.  */

          amt = strlen (l + sizeof REAL - 1) + 2;

          n = (char *) bfd_malloc (amt);

          if (n == NULL)

            return NULL;

          n[0] = prefix;

          n[1] = '\0';

          strcat (n, l + sizeof REAL - 1);

          h = bfd_link_hash_lookup (info->hash, n, create, TRUE, follow);

          free (n);

          return h;

        }

#undef REAL

    }

  return bfd_link_hash_lookup (info->hash, string, create, copy, follow);

}

/* Traverse a generic link hash table.  The only reason this is not a

   macro is to do better type checking.  This code presumes that an

   argument passed as a struct bfd_hash_entry * may be caught as a

   struct bfd_link_hash_entry * with no explicit cast required on the

   call.  */

void

bfd_link_hash_traverse

  (struct bfd_link_hash_table *table,

   bfd_boolean (*func) (struct bfd_link_hash_entry *, void *),

   void *info)

{

  bfd_hash_traverse (&table->table,

                     (bfd_boolean (*) (struct bfd_hash_entry *, void *)) func,

                     info);

}

/* Add a symbol to the linker hash table undefs list.  */

void

bfd_link_add_undef (struct bfd_link_hash_table *table,

                    struct bfd_link_hash_entry *h)

{

  BFD_ASSERT (h->u.undef.next == NULL);

  if (table->undefs_tail != NULL)

    table->undefs_tail->u.undef.next = h;

  if (table->undefs == NULL)

    table->undefs = h;

  table->undefs_tail = h;

}

/* The undefs list was designed so that in normal use we don't need to

   remove entries.  However, if symbols on the list are changed from

   bfd_link_hash_undefined to either bfd_link_hash_undefweak or

   bfd_link_hash_new for some reason, then they must be removed from the

   list.  Failure to do so might result in the linker attempting to add

   the symbol to the list again at a later stage.  */

void

bfd_link_repair_undef_list (struct bfd_link_hash_table *table)

{

  struct bfd_link_hash_entry **pun;

  pun = &table->undefs;

  while (*pun != NULL)

    {

      struct bfd_link_hash_entry *h = *pun;

      if (h->type == bfd_link_hash_new

          || h->type == bfd_link_hash_undefweak)

        {

          *pun = h->u.undef.next;

          h->u.undef.next = NULL;

          if (h == table->undefs_tail)

            {

              if (pun == &table->undefs)

                table->undefs_tail = NULL;

              else

                /* pun points at an u.undef.next field.  Go back to

                   the start of the link_hash_entry.  */

                table->undefs_tail = (struct bfd_link_hash_entry *)

                  ((char *) pun - ((char *) &h->u.undef.next - (char *) h));

              break;

            }

        }

      else

        pun = &h->u.undef.next;

    }

}

/* Routine to create an entry in a generic link hash table.  */

struct bfd_hash_entry *

_bfd_generic_link_hash_newfunc (struct bfd_hash_entry *entry,

                                struct bfd_hash_table *table,

                                const char *string)

{

  /* Allocate the structure if it has not already been allocated by a

     subclass.  */

  if (entry == NULL)

    {

      entry = (struct bfd_hash_entry *)

        bfd_hash_allocate (table, sizeof (struct generic_link_hash_entry));

      if (entry == NULL)

        return entry;

    }

  /* Call the allocation method of the superclass.  */

  entry = _bfd_link_hash_newfunc (entry, table, string);

  if (entry)

    {

      struct generic_link_hash_entry *ret;

      /* Set local fields.  */

      ret = (struct generic_link_hash_entry *) entry;

      ret->written = FALSE;

      ret->sym = NULL;

    }

  return entry;

}

/* Create a generic link hash table.  */

struct bfd_link_hash_table *

_bfd_generic_link_hash_table_create (bfd *abfd)

{

  struct generic_link_hash_table *ret;

  bfd_size_type amt = sizeof (struct generic_link_hash_table);

  ret = (struct generic_link_hash_table *) bfd_malloc (amt);

  if (ret == NULL)

    return NULL;

  if (! _bfd_link_hash_table_init (&ret->root, abfd,

                                   _bfd_generic_link_hash_newfunc,

                                   sizeof (struct generic_link_hash_entry)))

    {

      free (ret);

      return NULL;

    }

  return &ret->root;

}

void

_bfd_generic_link_hash_table_free (struct bfd_link_hash_table *hash)

{

  struct generic_link_hash_table *ret

    = (struct generic_link_hash_table *) hash;

  bfd_hash_table_free (&ret->root.table);

  free (ret);

}

/* Grab the symbols for an object file when doing a generic link.  We

   store the symbols in the outsymbols field.  We need to keep them

   around for the entire link to ensure that we only read them once.

   If we read them multiple times, we might wind up with relocs and

   the hash table pointing to different instances of the symbol

   structure.  */

bfd_boolean

bfd_generic_link_read_symbols (bfd *abfd)

{

  if (bfd_get_outsymbols (abfd) == NULL)

    {

      long symsize;

      long symcount;

      symsize = bfd_get_symtab_upper_bound (abfd);

      if (symsize < 0)

        return FALSE;

      bfd_get_outsymbols (abfd) = (struct bfd_symbol **) bfd_alloc (abfd,

                                                                    symsize);

      if (bfd_get_outsymbols (abfd) == NULL && symsize != 0)

        return FALSE;

      symcount = bfd_canonicalize_symtab (abfd, bfd_get_outsymbols (abfd));

      if (symcount < 0)

        return FALSE;

      bfd_get_symcount (abfd) = symcount;

    }

  return TRUE;

}

/* Generic function to add symbols to from an object file to the

   global hash table.  This version does not automatically collect

   constructors by name.  */

bfd_boolean

_bfd_generic_link_add_symbols (bfd *abfd, struct bfd_link_info *info)

{

  return generic_link_add_symbols (abfd, info, FALSE);

}

/* Generic function to add symbols from an object file to the global

   hash table.  This version automatically collects constructors by

   name, as the collect2 program does.  It should be used for any

   target which does not provide some other mechanism for setting up

   constructors and destructors; these are approximately those targets

   for which gcc uses collect2 and do not support stabs.  */

bfd_boolean

_bfd_generic_link_add_symbols_collect (bfd *abfd, struct bfd_link_info *info)

{

  return generic_link_add_symbols (abfd, info, TRUE);

}

/* Indicate that we are only retrieving symbol values from this

   section.  We want the symbols to act as though the values in the

   file are absolute.  */

void

_bfd_generic_link_just_syms (asection *sec,

                             struct bfd_link_info *info ATTRIBUTE_UNUSED)