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Date: Fri, 04 Feb 2011 17:47:00 -0000
From: Vladimir Simonov <sv@sw.ru>
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To: Tom Tromey <tromey@redhat.com>
CC: gdb-patches@sourceware.org
Subject: Re: gdb: Incorrect stack unwinding if compressed debug info is used
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On 02/04/2011 07:34 PM, Tom Tromey wrote:
>>>>>> "Vladimir" == Vladimir Simonov<sv@sw.ru>  writes:
>
> Vladimir>  I've spend some time and, looks like, found the problem. It is in
> Vladimir>  dwarf2_symbol_mark_computed function (dwarf2read.c). Check
> Vladimir>  "DW_UNSND (attr)<  dwarf2_per_objfile->loc.size"
> Vladimir>  is incorrect if compressed section is used.
>
> Thanks for finding this.
>
> Since fill_in_loclist_baton is going to read the loc section right away
> anyhow, it seems to me that it is simpler to just have
> dwarf2_symbol_mark_computed do it.
>
> Could you try the appended?
>
All is OK with it.
I'd also suggest to remove dwarf2_read_section from
fill_in_loclist_baton. Without it all works ok also.

But resulted code looks a bit hackish:
dwarf2_symbol_mark_computed (...)
{
   if (attr_form_is_section_offset (attr))
      /* We need to read the section before we can check its size,
         because the size is only valid once the section is
         uncompressed.  */
      dwarf2_read_section (dwarf2_per_objfile->objfile,
   		 &dwarf2_per_objfile->loc);
   if (attr_form_is_section_offset (attr)
       ........
        && DW_UNSND (attr)<  dwarf2_per_objfile->loc.size)
   )
   {
      ....
      fill_in_loclist_baton /* which uses results of dwarf2_read_section */
      ....
   }
...

Regards
Vladimir