[patch] Fix oddity in personality routine

Mon Nov 30 16:01:00 GMT 2009

On Mon, Nov 30, 2009 at 10:09:17AM +0000, Andrew Haley wrote:
> Jack Howarth wrote:
> > On Sun, Nov 29, 2009 at 06:00:57PM +0000, Andrew Haley wrote:
> >> Jack Howarth wrote:
> >>> 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:
>> >>>>
> >>> 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.
> >> It stops when unwinding java.lang.ClassLoader.loadClass(java.lang.String, boolean),
> >> either because the unwinder data is buggy (probably) or because the unwinder
> >> itself is buggy.
> > 
> > Would it help if I just used a breakpoint on uw_frame_state_for() and provided all
> > of the unwinding info that is being processed? Might that clarify if the unwinder
> > data is buggy?
>> Not really, no. The only thing now is to debug the unwinder at the point
> where the exception should be caught. You're seeing a bus error in the
> unwinder itself, which points to a failure to follow the chain of stack
> frames.
>> Andrew.

Andrew,
 I'll generate a complete debug walk from the last instance of the
_Unwind_RaiseException breakpoint before the crash tonight. I started
doing that this weekend but it was taking forever to complete the walk.
 What code actually generates the unwind info in gcj? Is it from libffi?
I might also drop back to the gcc 4.3.x releases in darwin9 to see if 
I can detect if this ever worked and if so when it regressed. However,
considering that Andreas has managed to get this to be suppressed at
times, I wonder if this issue has always been present on intel darwin
and just tends to go latent at times.
 Jack
ps It is odd that the unwind info generated for compiling classes with
gcj never seems to cause a problem. Could that be a clue as to the
segment of code at fault? I noticed that the ecjx.c source is a dummy
shell so I was unclear which code is used in gcj to compile java source
but not classes.