[PPL-devel] [Yap-users] Interfacing Yap with a C++ library

[Roberto Bagnara]

Vitor Santos Costa wrote:
> - The second possibility is that C++ needs a dynamic library, which is
> weird. You can try
> 
> configure --enable-dynamic-loading
> make clean
> make install
> 
> That should have a .so file.
> 
> Please tell me if you can't still make it work.

Dear Vitor,

since I have stumbled on exactly the same problem encountered by Pat,
I have tried the above suggestion.  This solves the problem indicated by
"usr/bin/ld: /usr/local/lib/libYap.a(c_interface.o): relocation
R_X86_64_32S against `Yap_REGS' can not be used when making a shared
object; recompile with -fPIC".  However, now there is another problem:

% Restoring file /usr/local/lib/Yap/startup
YAP version Yap-5.1.1
  % reconsulting /home/roberto/ppl/ppl/interfaces/Prolog/YAP/yap_pl_check.pl...
   % reconsulting /home/roberto/ppl/ppl/interfaces/Prolog/YAP/ppl_yap.pl...
%
%
% YAP OOOPS: tried to access illegal address 0x8!!!!.
%
%
1725KB of Code Space (0x8800000--0x89af4b0)
1KB of Global Stack (0x89b4000--0x89b4598)
2KB of Local Stack (0x8b3f768--0x8b40000)
0KB of Trail (0x8b40008--0x8b40088)
Performed 0 garbage collections
Running code at clause 1 of prolog:load_foreign_files/3
Continuation is at clause 1 of prolog:load_foreign_files/3
   clause 1 of prolog:load_foreign_files/3
   clause 2 of prolog:$do_yes_no/2
   clause 6 of prolog:$process_directive/3
   clause 5 of prolog:$execute_command/4
      indexing code of prolog:$catch/3 (*)
   clause 1 of prolog:$system_catch/4
   clause 1 of prolog:$loop/2
   clause 1 of prolog:$do_lf/9
   clause 7 of prolog:$lf/13
   clause 1 of prolog:$load_files/3
   clause 5 of prolog:$execute_command/4
      indexing code of prolog:$catch/3 (*)
   clause 1 of prolog:$system_catch/4
   clause 1 of prolog:$loop/2
   clause 1 of prolog:$do_lf/9
   clause 7 of prolog:$lf/13
   clause 1 of prolog:$load_files/3
      indexing code of prolog:$catch/3 (*)
   clause 1 of prolog:$system_catch/4
   clause 1 of prolog:$do_startup_reconsult/1
   clause 1 of prolog:$init_system/0
   clause 1 of prolog:$live/0

    Exiting ....

The problem disappears if I configure with

     configure --enable-dynamic-loading --enable-debug-yap

I have tried to disable all optimizations in order to better understand what
is going on using gdb, but with optimizations turned off, making Yap dies
at this point:

gcc  -rdynamic  -Wl,-R,NONE/lib -o yap yap.o libYap.so -lgmp -lreadline -lncurses -ltermcap -lm  -ldl -lnsl
/usr/bin/ld: yap: hidden symbol `stat' in /usr/lib64/libc_nonshared.a(stat.oS) is referenced by DSO
/usr/bin/ld: final link failed: Nonrepresentable section on output
collect2: ld returned 1 exit status

By configuring with

     CFLAGS="-g -O" ./configure --enable-dynamic-loading

I can use gdb to see where the illegal access at address 0x8 occurs:

% Restoring file /usr/local/lib/Yap/startup
YAP version Yap-5.1.1
  % reconsulting /home/roberto/ppl/ppl/interfaces/Prolog/YAP/yap_pl_check.pl...
   % reconsulting /home/roberto/ppl/ppl/interfaces/Prolog/YAP/ppl_yap.pl...

Program received signal SIGSEGV, Segmentation fault.
Yap_NewPredPropByFunctor (fe=0x89af410, cur_mod=142656577) at ./C/adtdefs.c:532
532       p->KindOfPE = PEProp;
(gdb) list
527       Prop p0;
528       PredEntry *p = (PredEntry *) Yap_AllocAtomSpace(sizeof(*p));
529
530       INIT_RWLOCK(p->PRWLock);
531       INIT_LOCK(p->PELock);
532       p->KindOfPE = PEProp;
533       p->ArityOfPE = fe->ArityOfFE;
534       p->cs.p_code.FirstClause = p->cs.p_code.LastClause = NULL;
535       p->cs.p_code.NOfClauses = 0;
536       p->PredFlags = 0L;
(gdb) print p
$1 = (PredEntry *) 0x0
(gdb) print &(p->KindOfPE)
$2 = (PropFlags *) 0x8
(gdb)

Does this shed any light?
Please let me know if I can do more to help locate the sources
of the problems.
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