PING: [PATCH v4] fixed inherit_abstract_dies infinite recursive call

[Joel Brobecker <brobecker at adacore dot com>]

Ping!

It would be interesting to have a formal review of this patch,
to know if it is an acceptable fix or not.  If not, I can schedule
some time to follow any recommendation that might come out of
this review.

Thank you!

On Tue, Jan 28, 2014 at 04:06:00PM +0400, Joel Brobecker wrote:
> >      > btw, do you have a copyright assignment on file?
> >      > This change feels small enough to me to not need one,
> >      > but it's not clear. 
> > 
> >      I am a Chinese guy,and Chinese have not clue about the copyright.
> >      (A joke.I don't need copyright.)
> 
> It's actually not for your personal benefit, but rather to help the FSF
> enforce the GPL license on the code you are contributing, thus helping
> it defend the freedom of our collective code. See:
> http://www.gnu.org/licenses/why-assign.html
> 
> > >>    Please Joel Brobecker <brobecker@adacore.com> helps with the testcases.
> 
> Attached is a testcase that causes the debugger to crash on
> x86_64-linux. It should work on all ELF targets.
> 
> A plea to the dwarf2read.c gurus:
> 
> Would it be possible to take a look at this patch, to see if it is
> going in the right direction? Otherwise, I'll take a deeper look,
> and see if I can solve it better. Intuitively, I think it may work,
> but almost as a side-effect. Could the recursion check introduced
> here do more than what we'd want to, for instance?
> 
> Thanks!
> 
> > >>>     The c++ code causing the problem is:
> > >>> 
> > >>>         // Integer variants of certain metrics, used for HTML rendering.
> > >>>         int ascent(FontBaseline baselineType = AlphabeticBaseline) const
> > >>>         {
> > >>>             if (baselineType == AlphabeticBaseline)
> > >>>                 return lroundf(m_ascent);
> > >>>             return height() - height() / 2;
> > >>>         }
> > >>> 
> > >>>         int height(FontBaseline baselineType = AlphabeticBaseline) const
> > >>>         {
> > >>>             return ascent(baselineType) + descent(baselineType);
> > >>>         }
> > >>> 
> > >>>     As you can see,ascent(0x5816d55) calls height(0x5812c1b),and height calls
> > >>>     ascent(0x5816d55) recursivly.And the compiler  generates these dwarf code
> > >>>     representing this relationship preciously.
> > >>> 
> > >>>     A dwarf die may have the following relationship:
> > >>>     564860c<-----------------------------
> > >>>       |                                 |
> > >>>       |(abstract origin)                |
> > >>>       |                                 |
> > >>>       V                                 |
> > >>>     5816d55                             | (abstract origin)
> > >>>       |                                 |
> > >>>       |(child)                          |
> > >>>       |                                 |
> > >>>       V                                 |
> > >>>       ...                               |
> > >>>     5812c34------------------------------
> > >>>     So inherit_abstract_dies may results in infinite recursive call.
> > >>>     A bit field call in_process has been add to struct die_info to fix this problem.
> > >>>     process_die would first check if a die is in processing state, if so,just return.
> > >>>     Then in_process bit is set.Before process_die returns,this bit field is unset.---
> >  ChangeLog        |  4 ++++
> >  gdb/dwarf2read.c | 20 ++++++++++++++++++++
> >  2 files changed, 24 insertions(+)
> > 
> > diff --git a/ChangeLog b/ChangeLog
> > index 9b1cbfa..0098a72 100644
> > --- a/ChangeLog
> > +++ b/ChangeLog
> > @@ -1,3 +1,7 @@
> > +2013-01-20  lin zuojian  <manjian2006@gmail.com>
> > +	* dwarf2read.c (struct die_info): New member in_process.
> > +	(reset_die_in_process): New function.
> > +	(process_die): Set it at the start, reset when returning.
> >  2013-12-19  Keven Boell  <keven.boell@intel.com>
> >  
> >  	* cp-namespace.c (cp_lookup_nested_symbol): Enable
> > diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
> > index 7ca527d..ffedde5 100644
> > --- a/gdb/dwarf2read.c
> > +++ b/gdb/dwarf2read.c
> > @@ -1225,6 +1225,9 @@ struct die_info
> >         type derived from this DIE.  */
> >      unsigned char building_fullname : 1;
> >  
> > +    /* True if this die is in process.  */
> > +    unsigned char in_process : 1;
> > +
> >      /* Abbrev number */
> >      unsigned int abbrev;
> >  
> > @@ -8008,11 +8011,27 @@ process_imported_unit_die (struct die_info *die, struct dwarf2_cu *cu)
> >      }
> >  }
> >  
> > +/* Reset the in_process bit of a die.  */
> > +
> > +static void
> > +reset_die_in_process (void *arg)
> > +{
> > +  struct die_info *die = arg;
> > +  die->in_process = 0;
> > +}
> > +
> >  /* Process a die and its children.  */
> >  
> >  static void
> >  process_die (struct die_info *die, struct dwarf2_cu *cu)
> >  {
> > +  struct cleanup *in_process;
> > +
> > +  /* Only process those not already in process.  */
> > +  if (die->in_process)
> > +    return;
> > +  die->in_process = 1;
> > +  in_process = make_cleanup (reset_die_in_process,die);
> >    switch (die->tag)
> >      {
> >      case DW_TAG_padding:
> > @@ -8100,6 +8119,7 @@ process_die (struct die_info *die, struct dwarf2_cu *cu)
> >        new_symbol (die, NULL, cu);
> >        break;
> >      }
> > +    do_cleanups (in_process);
> >  }
> >  
> >  /* DWARF name computation.  */
> > -- 
> > 1.8.3.2
> 
> -- 
> Joel

-- 
Joel