A weak symbol bug in gas-950819

Ian Lance Taylor ian@cygnus.com
Mon Aug 21 08:14:00 GMT 1995


   From: hjl@nynexst.com (H.J. Lu)
   Date: Sun, 20 Aug 1995 21:50:49 -0400 (EDT)

   There is a weak symbol bug in gas-950819. The old snapshots failed to
   pick up the real definition under certain circumstances. gas-950819
   failed to set the weak symbol to zero.

I'm not sure what you mean when you say that it failed to set the weak
symbol to zero.

I do see from your test case that the linker has a bug in the way it
handles an undefined weak reference followed by a weak reference.
I've checked in the appended patch, which should fix the problem.

   BTW, what an ELF linker should do with the symbol "xxx" in

   ld .... -lfoo -lbar

   where a real "xxx" is defined in libfoo.a, a weak one is defined in
   libbar.a and "xxx" is referenced in libbar.a only?

The linker processes libraries sequentially.  Assuming that there is
no mention of "xxx" before libfoo.a, and assuming that the definition
of "xxx" is not brought in from libfoo.a for some other reason,
libfoo.a is irrelevant to this case.

Ian

Index: linker.c
===================================================================
RCS file: /rel/cvsfiles/devo/bfd/linker.c,v
retrieving revision 1.58
diff -p -r1.58 linker.c
*** linker.c	1995/07/13 18:14:17	1.58
--- linker.c	1995/08/21 15:09:20
*************** enum link_action
*** 1321,1327 ****
  static const enum link_action link_action[8][8] =
  {
    /* current\prev    new    undef  undefw def    defw   com    indr   warn  */
!   /* UNDEF_ROW 	*/  {UND,   NOACT, NOACT, REF,   REF,   NOACT, REFC,  WARNC },
    /* UNDEFW_ROW	*/  {WEAK,  NOACT, NOACT, REF,   REF,   NOACT, REFC,  WARNC },
    /* DEF_ROW 	*/  {DEF,   DEF,   DEF,   MDEF,  DEF,   CDEF,  MDEF,  CYCLE },
    /* DEFW_ROW 	*/  {DEFW,  DEFW,  DEFW,  NOACT, NOACT, NOACT, NOACT, CYCLE },
--- 1321,1327 ----
  static const enum link_action link_action[8][8] =
  {
    /* current\prev    new    undef  undefw def    defw   com    indr   warn  */
!   /* UNDEF_ROW 	*/  {UND,   NOACT, UND,   REF,   REF,   NOACT, REFC,  WARNC },
    /* UNDEFW_ROW	*/  {WEAK,  NOACT, NOACT, REF,   REF,   NOACT, REFC,  WARNC },
    /* DEF_ROW 	*/  {DEF,   DEF,   DEF,   MDEF,  DEF,   CDEF,  MDEF,  CYCLE },
    /* DEFW_ROW 	*/  {DEFW,  DEFW,  DEFW,  NOACT, NOACT, NOACT, NOACT, CYCLE },
Index: elflink.h
===================================================================
RCS file: /rel/cvsfiles/devo/bfd/elflink.h,v
retrieving revision 1.9
diff -p -r1.9 elflink.h
*** elflink.h	1995/08/14 15:57:17	1.9
--- elflink.h	1995/08/21 15:09:22
*************** elf_link_add_archive_symbols (abfd, info
*** 155,161 ****
  	    continue;
  	  if (h->root.type != bfd_link_hash_undefined)
  	    {
! 	      defined[i] = true;
  	      continue;
  	    }
  
--- 155,162 ----
  	    continue;
  	  if (h->root.type != bfd_link_hash_undefined)
  	    {
! 	      if (h->root.type != bfd_link_hash_undefweak)
! 		defined[i] = true;
  	      continue;
  	    }
  




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