Re: [patch] Fix oddity in personality routine

[Jack Howarth <howarth at bromo dot med dot uc dot edu>]

On Sat, Nov 28, 2009 at 10:43:26AM +0000, Andrew Haley wrote:
> Jack Howarth wrote:
> > On Fri, Nov 27, 2009 at 10:40:17AM +0000, Andrew Haley wrote:
> >> borlum wrote:
> >>>
> >>> Jack Howarth-3 wrote:
> >>>> On Tue, Nov 17, 2009 at 05:13:31PM +0000, Andrew Haley wrote:
> >>>>> Sometimes it doesn't work, so you have to be inventive.  Try
> >>>>> setting a breakpoint on Unwind_RaiseException, or step a single
> >>>>> instruction at a time when you get to a call.
> >>>>>
> >>>>>> I assume that gcc trunk's
> >>>>>> debug code is still compatible with Apple's gdb. If not, I do have
> >>>>>> a build of gdb 7.0 on Intel darwin that I can use instead. Thanks
> >>>>>> in advance for any hints on this issue.
> >>>>>>               Jack
> >>>>>> ps I do notice that gdb can't find the object files from
> >>>>> /sw/src/fink.build/gcc45-4.4.999-20091116/darwin_objdir/x86_64-apple-darwin9.8.0/libjava/.libs/libgcj.lax
> >>>>> so it might have problems with debugging within libgcj. If I recall
> >>>>> correctly this .lax issue is known...
> >>>>>> http://gcc.gnu.org/ml/gcc/2008-10/msg00083.html
> >>>>> Ouch.  That will cause gdb breakage, for sure.
> >>>> Andrew,
> >>>>    Re-reading Peter's comments in
> >>>> http://gcc.gnu.org/ml/gcc/2008-10/msg00083.html, I think I
> >>>> may be able to work around the lax issue with the proper setting of
> >>>> LD_LIBRARY to point to 
> >>>> the shared library in the build directory. I'll see if I can puzzle that
> >>>> one out.
> >>>>                  Jack
> >>>>> Andrew.
> >>> Hey Andrew,
> >>>
> >>> Did you ever solve the problem? I'm having the same rather frustrating
> >>> error.
> >> Not me, no.  I don't have a Darwin system.
> 
> >     Now that we have a set of patches to fix the breakage in current gcc
> > trunk to dsymutil, I have uploaded a much more complete walk under x86_64-apple-darwin10.
> > I haven't managed to walk into _Unwind_Exception() yet but I do see that the 
> > crash occurs on continuing from the 39th instance of the _Unwind_Exception() breakpoint.
> 
> That's probably just the end of the stack.  If you do a stack trace
> in gdb you'll probably find it's something like 39 deep.
> 
> > Is there some way I can get the unwinder data from inside of libgcj itself before
> > the call to _Unwind_Exception()? If the bad unwind information is being generated in
> > libjava wouldn't it be just as easy to see that from outside of libgcc (before the call
> > to _Unwind_Exception()?
> 
> You mean decoding the unwinder data by hand?  It's not impossible, but
> it'd be a hell of a job.
> 
> Andrew.

Andrew,
   I managed to get a build of libgcc at -O0 under darwin9 that I used to walk through
the FSF gcc unwinder. The walk is at...

http://gcc.gnu.org/bugzilla/attachment.cgi?id=19174

and the list of the frames is at...

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41991#c26

Does this clarify the problem at all on intel darwin? Let me know if there
is any other particular debug information I can provide.
                  Jack