[PPL-devel] Re: Raising Prolog exceptions from C code (2nd attempt)

[Roberto Bagnara]

Daniele Peri wrote:
> Fri, 2002-06-07 19:25, Roberto Bagnara wrote:
> 
> 
>>in my application (http://www.cs.unipr.it/ppl/) and I observe exactly
>>the same segmentation violations and illegal instructions.
>>May it be because Pl_Exec_Continuation is implemented by means
>>of setjmp/longjmp and I am doing something that is incompatible
>>with them?  What can it be?
> 
> 
> I hope not to bother anyone telling again that this problem seems very
> similar to the one I experienced with my applications using GTK. I found
> that such problems arise when linking code compiled without using frame
> pointer (like many distribution libraries) and gprolog compiled with all
> the default optimizations (among them the use of frame pointer).
> Problems actually appear just with callbacks in the case of GTK so I
> think your hypothesis could be right. I made some test in gdb
> discovering a complete mess in the stack after a call from a GTK
> callback. In some cases I could make things work by modifying manually
> the stack pointer. I discussed it with Daniel Diaz but I haven't had the
> time to test it thoroughly as Daniel asked me. My simple solution, so
> far, is to compile GNUProlog and the "critic" libraries or source-code
> all in the same way. 

Dear Daniele,

thanks for your message.  Your analysis works!
I use the GMP library which, by default, is compiled with
-fomit-frame-pointer.  And I use the PPL library
(http://www.cs.unipr.it/ppl/) that, by default, is compiled
without -fomit-frame-pointer.
I have first tried to compile PPL with -fomit-frame-pointer
and then I discovered the bug of GCC 3.0.x whereby
C++ exceptions don't work with -fomit-frame-pointer.

Then I have tried compiling everything without -fomit-frame-pointer
and everything works OK: I can throw C++ exceptions, catch them
in C++ to convert them into GNU Prolog exceptions that can then
correctly be caught by Prolog code.

I really feel this is a strong limitation of GNU Prolog:
we cannot ask our users to recompile every library they use
so as to make sure that -fomit-frame-pointer is used or
left out consistently in all the builds.
Daniel, do you envisage any solution to this problem?
Can we do something to help?
All the best

     Roberto

-- 
Prof. Roberto Bagnara
Computer Science Group
Department of Mathematics, University of Parma, Italy
http://www.cs.unipr.it/~bagnara/
mailto:bagnara at cs.unipr.it