[PATCH] Fix handling of symbols with non-default visibility in discarded COMDAT group sections

[PATCH] Fix handling of symbols with non-default visibility in discarded COMDAT group sections

[Julian Brown]

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Hi,

This patch fixes a problem with hidden symbols in sections which are 
discarded through being part of a COMDAT group. It does this by forcing 
their visibility to be STV_DEFAULT (AIUI, other values are fairly 
meaningless in this context anyway). This fixes some interoperability 
problems with another compiler.

It prevents the error condition in elflink.c:elf_link_output_extsym from 
triggering ("If a non-weak symbol with non-default visibility is not 
defined locally, it is a fatal error"), and henceforth lets linking work 
correctly -- that is, that error condition seems to be the only thing 
preventing linking working in the first place. Changing the condition to 
allow hidden visibility too definitely seems like the wrong solution though.

References:

   http://sources.redhat.com/ml/binutils/2003-04/msg00055.html
   http://sources.redhat.com/ml/binutils/2004-12/msg00007.html

ChangeLog:

	* bfd/elflink.c (elf_link_add_object_symbols): Force symbols in
	discarded COMDAT group sections to have default visibility.

-- 
Julian Brown
CodeSourcery, LLC

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? bfd/.elflink.c.swp
? bfd/doc/bfd.info
? bfd/doc/bfd.info-1
Index: bfd/elflink.c
===================================================================
RCS file: /cvs/src/src/bfd/elflink.c,v
retrieving revision 1.134
diff -c -p -r1.134 elflink.c
*** bfd/elflink.c	11 Feb 2005 16:41:09 -0000	1.134
--- bfd/elflink.c	23 Feb 2005 15:45:59 -0000
*************** elf_link_add_object_symbols (bfd *abfd, 
*** 3575,3583 ****
  	    sec = bfd_abs_section_ptr;
  	  else if (sec->kept_section)
  	    {
! 	      /* Symbols from discarded section are undefined.  */
  	      sec = bfd_und_section_ptr;
  	      isym->st_shndx = SHN_UNDEF;
  	    }
  	  else if ((abfd->flags & (EXEC_P | DYNAMIC)) != 0)
  	    value -= sec->vma;
--- 3575,3586 ----
  	    sec = bfd_abs_section_ptr;
  	  else if (sec->kept_section)
  	    {
! 	      /* Symbols from discarded section are undefined, and have
! 	         default visibility.  */
  	      sec = bfd_und_section_ptr;
  	      isym->st_shndx = SHN_UNDEF;
+ 	      isym->st_other = STV_DEFAULT
+ 			       | (isym->st_other & ~ ELF_ST_VISIBILITY(-1));
  	    }
  	  else if ((abfd->flags & (EXEC_P | DYNAMIC)) != 0)
  	    value -= sec->vma;

Re: [PATCH] Fix handling of symbols with non-default visibility in discarded COMDAT group sections

[Julian Brown]

On 2005-02-23, Julian Brown <julian@codesourcery.com> wrote:
> This is a multi-part message in MIME format.
> --------------000602080904060105000704
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> Content-Transfer-Encoding: 7bit
>
> Hi,
>
> This patch fixes a problem with hidden symbols in sections which are 
> discarded through being part of a COMDAT group. It does this by forcing 
> their visibility to be STV_DEFAULT (AIUI, other values are fairly 
> meaningless in this context anyway). This fixes some interoperability 
> problems with another compiler.

Forgot to say: tested without regressions with cross to arm-none-eabi,
and with --enable-targets=all on i686 linux.

Julian

-- 
Julian Brown
CodeSourcery, LLC

Re: [PATCH] Fix handling of symbols with non-default visibility in discarded COMDAT group sections

[Alan Modra]

On Wed, Feb 23, 2005 at 04:11:11PM +0000, Julian Brown wrote:
> 	* bfd/elflink.c (elf_link_add_object_symbols): Force symbols in
> 	discarded COMDAT group sections to have default visibility.

OK.

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre