Re: [PATCH] don't include symbols from S_ATTR_NO_TOC sections in mach-o canonical symtab output

[Tristan Gingold <gingold at adacore dot com>]

On Oct 29, 2013, at 6:54 PM, Nathan Froyd <froydnj@mozilla.com> wrote:

> Hi,
> 
> Generating static library archives with binutils and comparing them with
> archives produced by Apple's tools reveals one significant difference:
> those produced by Apple's tools are significantly smaller.  binutils
> includes many ${SYMBOL_NAME}.eh symbols in the archive table of contents,
> whereas Apple's tools do not.
> 
> This difference is due to the .eh symbols living in the .eh_frame section,
> which is tagged with the Mach-O section flag S_ATTR_NO_TOC.  This flag
> instructs the archiver to not include symbols from such a section in the
> table of contents for an archive.
> 
> The patch below changes bfd_mach_o_canonicalize_symtab to respect this flag.
> 
> Tested on x86_64-apple-darwin11, no regressions.  OK to checkin?

Yes, this is OK.

(Interesting to know that GNU ar is used on Darwin :-)

Tristan.

> 
> -Nathan
> 
> 	* mach-o.c (bfd_mach_o_canonicalize_symtab): Respect the
> 	BFD_MACH_O_S_ATTR_NO_TOC flag on symbol sections.
> ---
> bfd/mach-o.c |   21 ++++++++++++++++-----
> 1 file changed, 16 insertions(+), 5 deletions(-)
> 
> diff --git a/bfd/mach-o.c b/bfd/mach-o.c
> index 32e48ac..095afeb 100644
> --- a/bfd/mach-o.c
> +++ b/bfd/mach-o.c
> @@ -630,7 +630,7 @@ bfd_mach_o_canonicalize_symtab (bfd *abfd, asymbol **alocation)
>   bfd_mach_o_data_struct *mdata = bfd_mach_o_get_data (abfd);
>   long nsyms = bfd_mach_o_count_symbols (abfd);
>   bfd_mach_o_symtab_command *sym = mdata->symtab;
> -  unsigned long j;
> +  unsigned long i, j;
> 
>   if (nsyms < 0)
>     return nsyms;
> @@ -651,12 +651,23 @@ bfd_mach_o_canonicalize_symtab (bfd *abfd, asymbol **alocation)
> 
>   BFD_ASSERT (sym->symbols != NULL);
> 
> -  for (j = 0; j < sym->nsyms; j++)
> -    alocation[j] = &sym->symbols[j].symbol;
> +  for (i = 0, j = 0; j < sym->nsyms; j++)
> +    {
> +      bfd_mach_o_asymbol *asym = &sym->symbols[j];
> +      if (asym->n_sect != 0)
> +	{
> +	  bfd_mach_o_section *sect = mdata->sections[asym->n_sect-1];
> +	  if (sect->flags & BFD_MACH_O_S_ATTR_NO_TOC)
> +	    continue;
> +	}
> 
> -  alocation[j] = NULL;
> +      alocation[i] = &asym->symbol;
> +      i++;
> +    }
> +
> +  alocation[i] = NULL;
> 
> -  return nsyms;
> +  return i;
> }
> 
> /* Create synthetic symbols for indirect symbols.  */
> -- 
> 1.7.9.5
>