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Re: RFA: don't read coff line number unless we have symbols too
- From: Jim Blandy <jimb at redhat dot com>
- To: gdb-patches at sources dot redhat dot com
- Date: 22 Aug 2002 00:42:02 -0500
- Subject: Re: RFA: don't read coff line number unless we have symbols too
- References: <200206260803.g5Q83f028100@mail.macqel.be><npwusl99xg.fsf@zwingli.cygnus.com>
Joel Brobecker has said in private E-mail that his earlier concerns
have been addressed, so I've committed this change.
Jim Blandy <jimb@redhat.com> writes:
> "Philippe De Muyter" <phdm@macqel.be> writes:
> > Should the following lines not be kept outside of the conditional block ?
> >
> > info->min_lineno_offset = 0;
> > info->max_lineno_offset = 0;
>
> Sure, those can be moved outside.
>
> I was just thinking of those as just establishing the pre-condition
> for the loop that bfd_map_over_sections does. Those fields are never
> used outside the "read the line number table" block, and the worker
> function for bfd_map_over_sections --- effectively, the loop body. In
> that light, it makes more sense to keep them right next to the call,
> as they are in the original code.
>
> Here's a revised patch, if you prefer the initializations outside.
>
> 2002-03-06 Jim Blandy <jimb@redhat.com>
>
> * coffread.c (coff_symfile_read): Don't try to read the line
> number table from disk if the image file doesn't have a symbol
> table; we'll never actually look at the info anyway, and Windows
> ships DLL's with bogus file offsets for the line number data.
>
> Index: gdb/coffread.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/coffread.c,v
> retrieving revision 1.26
> diff -c -r1.26 coffread.c
> *** gdb/coffread.c 19 Mar 2002 19:00:03 -0000 1.26
> --- gdb/coffread.c 26 Jun 2002 18:19:07 -0000
> ***************
> *** 593,608 ****
>
> /* End of warning */
>
> - /* Read the line number table, all at once. */
> info->min_lineno_offset = 0;
> info->max_lineno_offset = 0;
> - bfd_map_over_sections (abfd, find_linenos, (void *) info);
>
> ! make_cleanup (free_linetab_cleanup, 0 /*ignore*/);
> ! val = init_lineno (abfd, info->min_lineno_offset,
> ! info->max_lineno_offset - info->min_lineno_offset);
> ! if (val < 0)
> ! error ("\"%s\": error reading line numbers\n", name);
>
> /* Now read the string table, all at once. */
>
> --- 593,626 ----
>
> /* End of warning */
>
> info->min_lineno_offset = 0;
> info->max_lineno_offset = 0;
>
> ! /* Only read line number information if we have symbols.
> !
> ! On Windows NT, some of the system's DLL's have sections with
> ! PointerToLinenumbers fields that are non-zero, but point at
> ! random places within the image file. (In the case I found,
> ! KERNEL32.DLL's .text section has a line number info pointer that
> ! points into the middle of the string `lib\\i386\kernel32.dll'.)
> !
> ! However, these DLL's also have no symbols. The line number
> ! tables are meaningless without symbols. And in fact, GDB never
> ! uses the line number information unless there are symbols. So we
> ! can avoid spurious error messages (and maybe run a little
> ! faster!) by not even reading the line number table unless we have
> ! symbols. */
> ! if (num_symbols > 0)
> ! {
> ! /* Read the line number table, all at once. */
> ! bfd_map_over_sections (abfd, find_linenos, (void *) info);
> !
> ! make_cleanup (free_linetab_cleanup, 0 /*ignore*/);
> ! val = init_lineno (abfd, info->min_lineno_offset,
> ! info->max_lineno_offset - info->min_lineno_offset);
> ! if (val < 0)
> ! error ("\"%s\": error reading line numbers\n", name);
> ! }
>
> /* Now read the string table, all at once. */
>