> What do you think about adding a new method inside struct sym_fns: 
> 
>         void (*sym_read_linetable) (void)
> 
> It would be null for all object formats except XCOFF.
> 
> I'll experiment with that... Thanks for your feedback!

Here is a patch that implements exactly this.

2007-09-20  Joel Brobecker  <brobecker@adacore.com>

        * symfile.h (struct sym_fns): Add new field sym_read_linetable.
        * coffread.c, dbxread.c, elfread.c, mipsread.c somread.c:
        Adjust the struct sym_fns object accordingly by setting
        the new field to NULL.
        * xcoffread.c (aix_process_linenos): Make static.
        (xcoff_sym_fns): Set new field to aix_process_linenos.
        * buildsym.c (end_symtab): Replace call to PROCESS_LINENUMBER_HOOK
        by call to new the new sym_fns sym_read_linetable function.
        * config/powerpc/aix.mt (DEPRECATED_TM_FILE): Delete.
        * config/rs6000/tm-rs6000.h: Delete.

Tested on powerpc-aix and x86-linux, no regression. Does it look good?

Thank you,
-- 
Joel