Re: [RFA] Fix for searching for data symbols

[Michael Snyder <msnyder@redhat.com>]

Daniel Jacobowitz wrote:
> 
> This patch fixes the problem I described in:
>         http://sources.redhat.com/ml/gdb/2002-01/msg00223.html
> 
> Basically, since we use the bounds of the text segment to search for symbols
> in find_pc_*, don't let them return a bogus answer for a symbol we know is
> off in data land.
> 
> OK to commit, or does anyone prefer a different approach to this?

Is there any chance that a data symbol that we don't want
would shadow a text symbol that we do want?  Eg. maybe in
one module we have
	static int foo;
and in another we have
	extern int foo(void);
Maybe they are even in separate objfiles (shared libs).
Maybe lookup_minimal_symbol will find the wrong one first, 
and your change will terminate the search before we would
have found the right one?

Just speculating...

> 
> --
> Daniel Jacobowitz                           Carnegie Mellon University
> MontaVista Software                         Debian GNU/Linux Developer
> 
> 2002-01-19  Daniel Jacobowitz  <drow@mvista.com>
> 
>         * symtab.c (find_pc_sect_psymtab): Do not search psymtabs for
>         data symbols, since we search based on textlow and texthigh.
>         (find_pc_sect_symtab): Likewise.
> 
> Index: symtab.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/symtab.c,v
> retrieving revision 1.51
> diff -u -p -r1.51 symtab.c
> --- symtab.c    2001/12/21 22:32:37     1.51
> +++ symtab.c    2002/01/19 17:29:09
> @@ -354,12 +354,22 @@ find_pc_sect_psymtab (CORE_ADDR pc, asec
>  {
>    register struct partial_symtab *pst;
>    register struct objfile *objfile;
> +  struct minimal_symbol *msymbol;
> 
> +  /* If we know that this is not a text address, return failure.  */
> +  msymbol = lookup_minimal_symbol_by_pc_section (pc, section);
> +  if (msymbol
> +      && (msymbol->type == mst_data
> +         || msymbol->type == mst_bss
> +         || msymbol->type == mst_abs
> +         || msymbol->type == mst_file_data
> +         || msymbol->type == mst_file_bss))
> +    return NULL;
> +
>    ALL_PSYMTABS (objfile, pst)
>    {
>      if (pc >= pst->textlow && pc < pst->texthigh)
>        {
> -       struct minimal_symbol *msymbol;
>         struct partial_symtab *tpst;
> 
>         /* An objfile that has its functions reordered might have
> @@ -370,7 +380,6 @@ find_pc_sect_psymtab (CORE_ADDR pc, asec
>             section == 0)       /* can't validate section this way */
>           return (pst);
> 
> -       msymbol = lookup_minimal_symbol_by_pc_section (pc, section);
>         if (msymbol == NULL)
>           return (pst);
> 
> @@ -1385,6 +1394,17 @@ find_pc_sect_symtab (CORE_ADDR pc, asect
>    register struct partial_symtab *ps;
>    register struct objfile *objfile;
>    CORE_ADDR distance = 0;
> +  struct minimal_symbol *msymbol;
> +
> +  /* If we know that this is not a text address, return failure.  */
> +  msymbol = lookup_minimal_symbol_by_pc_section (pc, section);
> +  if (msymbol
> +      && (msymbol->type == mst_data
> +         || msymbol->type == mst_bss
> +         || msymbol->type == mst_abs
> +         || msymbol->type == mst_file_data
> +         || msymbol->type == mst_file_bss))
> +    return NULL;
> 
>    /* Search all symtabs for the one whose file contains our address, and which
>       is the smallest of all the ones containing the address.  This is designed