Re: [RFC/RFA] find_pc_sect_psymtab(): symbol table not always complete

[Daniel Jacobowitz <drow@mvista.com>]

On Wed, Nov 19, 2003 at 04:23:59PM -0800, Joel Brobecker wrote:
> > > 2003-11-19  J. Brobecker  <brobecker@gnat.com>
> > > 
> > >         * symtab.c (find_pc_sect_psymtab): Refine the search for the
> > >         partial symtab corresponding to the given PC address, taking
> > >         into account the fact that the symbol table might be incomplete.
> > 
> > FWIW, this looks good to me, but I'd like another comment on the new
> > test to the effect of, the find_pc_sect_psymtab call will always return
> > the closest symbol below pc in tpst.  Threw me for a moment how you
> > were just checking for the highest valued symbol.
> 
> Thanks for your feedback Daniel. I agree on that a comment is useful.
> Here is a revised version of the patch. Is it better?

This looks great to me.  It'll need to be approved by the symtab
maintainers.

> Index: symtab.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/symtab.c,v
> retrieving revision 1.122
> diff -u -p -r1.122 symtab.c
> --- symtab.c	8 Nov 2003 00:13:03 -0000	1.122
> +++ symtab.c	20 Nov 2003 00:21:30 -0000
> @@ -698,6 +698,8 @@ find_pc_sect_psymtab (CORE_ADDR pc, asec
>      if (pc >= pst->textlow && pc < pst->texthigh)
>        {
>  	struct partial_symtab *tpst;
> +       struct partial_symtab *best_pst = pst;
> +       struct partial_symbol *best_psym = NULL;
>  
>  	/* An objfile that has its functions reordered might have
>  	   many partial symbol tables containing the PC, but
> @@ -710,6 +712,11 @@ find_pc_sect_psymtab (CORE_ADDR pc, asec
>  	if (msymbol == NULL)
>  	  return (pst);
>  
> +       /* The code range of partial symtabs sometimes overlap, so
> +          we need to check all partial symtabs and find the one that
> +          fits better for the given PC address. We select the partial
> +          symtab that contains a symbol which address is closest to
> +          the PC address.  */
>  	for (tpst = pst; tpst != NULL; tpst = tpst->next)
>  	  {
>  	    if (pc >= tpst->textlow && pc < tpst->texthigh)
> @@ -721,9 +728,24 @@ find_pc_sect_psymtab (CORE_ADDR pc, asec
>  		    && SYMBOL_VALUE_ADDRESS (p)
>  		    == SYMBOL_VALUE_ADDRESS (msymbol))
>  		  return (tpst);
> +                 if (p != NULL)
> +                   {
> +                     /* We found a symbol in this partial symtab which
> +                        matches PC, check whether it is closer than our
> +                        current BEST_PSYM.  Since this symbol address is
> +                        necessarily lower or equal to PC, the symbol closer
> +                        to PC is the symbol which address is the highest.  */
> +                     if (best_psym == NULL
> +                         || SYMBOL_VALUE_ADDRESS (p)
> +                              > SYMBOL_VALUE_ADDRESS (best_psym))
> +                       {
> +                         best_psym = p;
> +                         best_pst = tpst;
> +                       }
> +                   }
>  	      }
>  	  }
> -	return (pst);
> +       return best_pst;
>        }
>    }
>    return (NULL);


-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer