fixes to new signal handling/debugging code

C/absmi.c

@@ -657,6 +657,7 @@ interrupt_handler( USES_REGS1 )
   int v;
   PredEntry *pe = (PredEntry *)S;
   
+  //  printf("D %lx %p\n", LOCAL_ActiveSignals, P);
   if ((v = check_alarm_fail_int( FALSE PASS_REGS )) != 1)
     return v;
   /* tell whether we can creep or not, this is hard because we will
@@ -833,6 +834,7 @@ interrupt_call( USES_REGS1 )
   int v;
   
   check_alarm_fail_int( TRUE PASS_REGS );
+  //  printf("%lx %p %p %lx\n", LOCAL_ActiveSignals, P->u.Osbpp.p, P->u.Osbpp.p0, P->u.Osbpp.p0->ExtraPredFlags);
   PP = P->u.Osbpp.p0;
   if ((PP->ExtraPredFlags & NoDebugPredFlag) && (LOCAL_ActiveSignals == YAP_CREEP_SIGNAL))
     return 2;
@@ -850,9 +852,9 @@ interrupt_pexecute( PredEntry *pen USES_REGS )
 
   check_alarm_fail_int( 2 PASS_REGS );
   PP = NULL;
-  if ((PP->ExtraPredFlags & NoDebugPredFlag) && (LOCAL_ActiveSignals == YAP_CREEP_SIGNAL))
+  if (LOCAL_ActiveSignals == YAP_CREEP_SIGNAL)
-    return 2;
+    return 2; /* keep on creeping */
-  S = (CELL *) P->u.Osbpp.p;
+  S = (CELL *) pen;
   ASP = YENV;
   if (ASP > (CELL *)PROTECT_FROZEN_B(B))
     ASP = (CELL *)PROTECT_FROZEN_B(B);
@@ -3220,6 +3222,14 @@ Yap_absmi(int inp)
 	PredEntry *pt0;
 	CACHE_Y_AS_ENV(YREG);
 	pt0 = PREG->u.pp.p;
+#ifndef NO_CHECKING
+	check_stack(NoStackExecute, H);
+	goto skip_do_execute;
+#endif
+      do_execute:
+	FETCH_Y_FROM_ENV(YREG);	
+	pt0 = PREG->u.pp.p;
+      skip_do_execute:
 #ifdef LOW_LEVEL_TRACER
 	if (Yap_do_low_level_trace) {
 	  low_level_trace(enter_pred,pt0,XREGS+1);
@@ -3229,15 +3239,6 @@ Yap_absmi(int inp)
 	ALWAYS_LOOKAHEAD(pt0->OpcodeOfPred);
 	BEGD(d0);
 	d0 = (CELL)B;
-#ifndef NO_CHECKING
-	check_stack(NoStackExecute, H);
-	goto skip_do_execute;
-#endif
-      do_execute:
-	FETCH_Y_FROM_ENV(YREG);	
-	pt0 = PREG->u.pp.p;
-	d0 = (CELL)B;
-      skip_do_execute:
 	PREG = pt0->CodeOfPred;
 	/* for profiler */
 	save_pc();
@@ -3258,6 +3259,10 @@ Yap_absmi(int inp)
 	ALWAYS_END_PREFETCH();
 	ENDCACHE_Y_AS_ENV();
       }
+
+    NoStackExecute:
+      PROCESS_INT(interrupt_execute, do_execute);
+
       ENDBOp();
 
       /* dexecute    Label               */
@@ -7387,6 +7392,10 @@ Yap_absmi(int inp)
 
 	BEGD(d0);
 	CACHE_Y_AS_ENV(YREG);
+#ifndef NO_CHECKING
+	check_stack(NoStackExecuteC, H);
+      do_executec:
+#endif
 #ifdef FROZEN_STACKS
 	{ 
 	  choiceptr top_b = PROTECT_FROZEN_B(B);
@@ -7411,9 +7420,6 @@ Yap_absmi(int inp)
 	CACHE_A1();
 	BEGD(d0);
 	d0 = (CELL)B;
-#ifndef NO_CHECKING
-	check_stack(NoStackExecute, H);
-#endif
 	/* for profiler */
 	save_pc();
 	ENV_YREG[E_CB] = d0;
@@ -7461,8 +7467,8 @@ Yap_absmi(int inp)
 	ENDD(d0);
       }
 
-    NoStackExecute:
+    NoStackExecuteC:
-      PROCESS_INT(interrupt_execute, do_execute);
+      PROCESS_INT(interrupt_execute, do_executec);
       ENDBOp();
 
       /* Like previous, the only difference is that we do not */
@@ -13595,6 +13601,7 @@ Yap_absmi(int inp)
 #ifndef NO_CHECKING
 	check_stack(NoStackPExecute, H);
 #endif
+      execute_stack_checked:
 	CPREG = NEXTOP(PREG, Osbmp);
 	ALWAYS_LOOKAHEAD(pen->OpcodeOfPred);
 	PREG = pen->CodeOfPred;
@@ -13645,8 +13652,8 @@ Yap_absmi(int inp)
 	d0 = interrupt_pexecute( pen PASS_REGS );
 	setregs();
 	if (!d0) FAIL();
-	if (d0 == 2) goto execute_end;
+	if (d0 == 2) goto execute_stack_checked;
-	JMPNext();
+	goto execute_end;
 	ENDBOp();
 
 	ENDD(d0);

C/adtdefs.c

@@ -872,7 +872,7 @@ Yap_NewPredPropByFunctor(FunctorEntry *fe, Term cur_mod)
       p->PredFlags |= GoalExPredFlag;
     }
   }
-  if (LOCAL_PL_local_data_p== NULL || truePrologFlag(PLFLAG_DEBUGINFO)) {
+  if (LOCAL_PL_local_data_p== NULL || !truePrologFlag(PLFLAG_DEBUGINFO)) {
     p->ExtraPredFlags |= NoDebugPredFlag;
   }
   p->FunctorOfPred = fe;
@@ -927,7 +927,7 @@ Yap_NewThreadPred(PredEntry *ap USES_REGS)
   LOCAL_ThreadHandle.local_preds = p;
   p->FunctorOfPred = ap->FunctorOfPred;
   Yap_inform_profiler_of_clause(&(p->OpcodeOfPred), &(p->OpcodeOfPred)+1, p, GPROF_NEW_PRED_THREAD);
-  if (LOCAL_PL_local_data_p== NULL || truePrologFlag(PLFLAG_DEBUGINFO)) {
+  if (LOCAL_PL_local_data_p== NULL || !truePrologFlag(PLFLAG_DEBUGINFO)) {
     p->ExtraPredFlags |= NoDebugPredFlag;
   }
   if (!(p->PredFlags & (CPredFlag|AsmPredFlag))) {
@@ -998,7 +998,7 @@ Yap_NewPredPropByAtom(AtomEntry *ae, Term cur_mod)
   AddPropToAtom(ae, (PropEntry *)p);
   p0 = AbsPredProp(p);
   p->FunctorOfPred = (Functor)AbsAtom(ae);
-  if (LOCAL_PL_local_data_p== NULL || truePrologFlag(PLFLAG_DEBUGINFO)) {
+  if (LOCAL_PL_local_data_p== NULL || !truePrologFlag(PLFLAG_DEBUGINFO)) {
     p->ExtraPredFlags |= NoDebugPredFlag;
   }
   WRITE_UNLOCK(ae->ARWLock);

C/exec.c

@@ -166,8 +166,8 @@ do_execute(Term t, Term mod USES_REGS)
   if (PRED_GOAL_EXPANSION_ALL) {
     LOCK(LOCAL_SignalLock);
     /* disable creeping when we do goal expansion */
-    if (LOCAL_ActiveSignals & (YAP_CREEP_SIGNAL|YAP_DELAY_CREEP_SIGNAL) && !LOCAL_InterruptsDisabled) {
+    if (LOCAL_ActiveSignals & (YAP_CREEP_SIGNAL) && !LOCAL_InterruptsDisabled) {
-      LOCAL_ActiveSignals &= ~(YAP_CREEP_SIGNAL|YAP_DELAY_CREEP_SIGNAL);
+      LOCAL_ActiveSignals &= ~(YAP_CREEP_SIGNAL);
       CalculateStackGap( PASS_REGS1 );
     }
     UNLOCK(LOCAL_SignalLock);
@@ -339,8 +339,8 @@ do_execute_n(Term t, Term mod, unsigned int n USES_REGS)
   if (PRED_GOAL_EXPANSION_ALL) {
     LOCK(LOCAL_SignalLock);
     /* disable creeping when we do goal expansion */
-    if (LOCAL_ActiveSignals & (YAP_CREEP_SIGNAL|YAP_DELAY_CREEP_SIGNAL) && !LOCAL_InterruptsDisabled) {
+    if (LOCAL_ActiveSignals & (YAP_CREEP_SIGNAL) && !LOCAL_InterruptsDisabled) {
-      LOCAL_ActiveSignals &= ~(YAP_CREEP_SIGNAL|YAP_DELAY_CREEP_SIGNAL);
+      LOCAL_ActiveSignals &= ~(YAP_CREEP_SIGNAL);
       CalculateStackGap( PASS_REGS1 );
     }
     UNLOCK(LOCAL_SignalLock);
@@ -641,8 +641,8 @@ p_execute_clause( USES_REGS1 )
   } else {
     code = Yap_ClauseFromTerm(clt)->ClCode;
   }
-  if (LOCAL_ActiveSignals & (YAP_CREEP_SIGNAL|YAP_DELAY_CREEP_SIGNAL)) {
+  if (LOCAL_ActiveSignals & (YAP_CREEP_SIGNAL)) {
-    LOCAL_ActiveSignals &= ~(YAP_CREEP_SIGNAL|YAP_DELAY_CREEP_SIGNAL);
+    LOCAL_ActiveSignals &= ~(YAP_CREEP_SIGNAL);
     Yap_signal(YAP_CREEP_SIGNAL);
   }
   return CallPredicate(RepPredProp(pe), cut_cp, code PASS_REGS);
@@ -657,7 +657,7 @@ p_execute_in_mod( USES_REGS1 )
 static Int
 p_do_goal_expansion( USES_REGS1 )
 {
-  Int creeping = LOCAL_ActiveSignals & (YAP_CREEP_SIGNAL|YAP_DELAY_CREEP_SIGNAL);
+  Int creeping = LOCAL_ActiveSignals & (YAP_CREEP_SIGNAL);
   Int out = FALSE;
   PredEntry *pe;
   Term cmod = Deref(ARG2);
@@ -665,7 +665,7 @@ p_do_goal_expansion( USES_REGS1 )
   ARG2 = ARG3;
   /* disable creeping */
   LOCK(LOCAL_SignalLock);
-  LOCAL_ActiveSignals &= ~(YAP_CREEP_SIGNAL|YAP_DELAY_CREEP_SIGNAL);    
+  LOCAL_ActiveSignals &= ~(YAP_CREEP_SIGNAL);    
   if (!LOCAL_ActiveSignals)
     CalculateStackGap( PASS_REGS1 );
   UNLOCK(LOCAL_SignalLock);
@@ -720,14 +720,14 @@ p_do_goal_expansion( USES_REGS1 )
 static Int
 p_do_term_expansion( USES_REGS1 )
 {
-  Int creeping = LOCAL_ActiveSignals & (YAP_CREEP_SIGNAL|YAP_DELAY_CREEP_SIGNAL);
+  Int creeping = LOCAL_ActiveSignals & (YAP_CREEP_SIGNAL);
   Int out = FALSE;
   PredEntry *pe;
   Term cmod = CurrentModule;
 
   /* disable creeping */
   LOCK(LOCAL_SignalLock);
-  LOCAL_ActiveSignals &= ~(YAP_CREEP_SIGNAL|YAP_DELAY_CREEP_SIGNAL);
+  LOCAL_ActiveSignals &= ~(YAP_CREEP_SIGNAL);
   if (!LOCAL_ActiveSignals)
     CalculateStackGap( PASS_REGS1 );
   UNLOCK(LOCAL_SignalLock);
@@ -903,8 +903,8 @@ p_execute_nonstop( USES_REGS1 )
   /*	N = arity; */
   /* call may not define new system predicates!! */
   if (RepPredProp(pe)->PredFlags & SpiedPredFlag) {
-    if (LOCAL_ActiveSignals & (YAP_CREEP_SIGNAL|YAP_DELAY_CREEP_SIGNAL)  && !LOCAL_InterruptsDisabled) {
+    if (LOCAL_ActiveSignals & (YAP_CREEP_SIGNAL)  && !LOCAL_InterruptsDisabled) {
-      LOCAL_ActiveSignals &= ~(YAP_CREEP_SIGNAL|YAP_DELAY_CREEP_SIGNAL);
+      LOCAL_ActiveSignals &= ~(YAP_CREEP_SIGNAL);
       Yap_signal(YAP_CREEP_SIGNAL);
     }
 #if defined(YAPOR) || defined(THREADS)

C/signals.c

@@ -54,7 +54,7 @@ inline static void
 undo_signal(yap_signals sig USES_REGS)
 {
   LOCK(LOCAL_SignalLock);
-  if ((LOCAL_ActiveSignals & ~(YAP_CREEP_SIGNAL|YAP_DELAY_CREEP_SIGNAL)) == sig) {
+  if ((LOCAL_ActiveSignals & ~(YAP_CREEP_SIGNAL)) == sig) {
     CalculateStackGap( PASS_REGS1 );
   }
   LOCAL_ActiveSignals &= ~sig;
@@ -91,7 +91,7 @@ static Int
 p_stop_creeping( USES_REGS1 )
 {
   LOCK(LOCAL_SignalLock);
-  LOCAL_ActiveSignals &= ~(YAP_CREEP_SIGNAL|YAP_DELAY_CREEP_SIGNAL);
+  LOCAL_ActiveSignals &= ~(YAP_CREEP_SIGNAL);
   if (!LOCAL_ActiveSignals) {
     CalculateStackGap( PASS_REGS1 );
   }
@@ -99,21 +99,6 @@ p_stop_creeping( USES_REGS1 )
   return TRUE;
 }
 
-static Int 
-p_meta_creep( USES_REGS1 )
-{
-  Atom            at;
-  PredEntry      *pred;
-
-  at = AtomCreep;
-  pred = RepPredProp(PredPropByFunc(Yap_MkFunctor(at, 1),0));
-  CreepCode = pred;
-  LOCK(LOCAL_SignalLock);
-  LOCAL_ActiveSignals |= YAP_DELAY_CREEP_SIGNAL;
-  UNLOCK(LOCAL_SignalLock);
-  return TRUE;
-}
-
 static Int
 p_creep_allowed( USES_REGS1 )
 {
@@ -221,12 +206,6 @@ p_first_signal( USES_REGS1 )
     UNLOCK(LOCAL_SignalLock);
     return Yap_unify(ARG1, MkAtomTerm(AtomSigVTAlarm));
   }
-  if (LOCAL_ActiveSignals & YAP_DELAY_CREEP_SIGNAL) {
-    LOCAL_ActiveSignals &= ~(YAP_CREEP_SIGNAL|YAP_DELAY_CREEP_SIGNAL);
-    MUTEX_UNLOCK(&(LOCAL_ThreadHandle.tlock));
-    UNLOCK(LOCAL_SignalLock);
-    return Yap_unify(ARG1, MkAtomTerm(AtomSigDelayCreep));
-  }
   if (LOCAL_ActiveSignals & YAP_CREEP_SIGNAL) {
     LOCAL_ActiveSignals &= ~YAP_CREEP_SIGNAL;
     MUTEX_UNLOCK(&(LOCAL_ThreadHandle.tlock));
@@ -302,12 +281,6 @@ p_continue_signals( USES_REGS1 )
   if (LOCAL_ActiveSignals & YAP_CREEP_SIGNAL) {
     Yap_signal(YAP_CREEP_SIGNAL);
   }
-  if (LOCAL_ActiveSignals & YAP_DELAY_CREEP_SIGNAL) {
-    Yap_signal(YAP_DELAY_CREEP_SIGNAL|YAP_CREEP_SIGNAL);
-  }
-  if (LOCAL_ActiveSignals & YAP_TRACE_SIGNAL) {
-    Yap_signal(YAP_TRACE_SIGNAL);
-  }
   if (LOCAL_ActiveSignals & YAP_DEBUG_SIGNAL) {
     Yap_signal(YAP_DEBUG_SIGNAL);
   }
@@ -333,7 +306,6 @@ Yap_InitSignalCPreds(void)
   /* Basic predicates for the debugger */
   Yap_InitCPred("$creep", 0, p_creep, SafePredFlag);
   Yap_InitCPred("$creep_fail", 0, p_creep_fail, SafePredFlag);
-  Yap_InitCPred("$meta_creep", 0, p_meta_creep, SafePredFlag);
   Yap_InitCPred("$stop_creeping", 0, p_stop_creeping, SafePredFlag);
   Yap_InitCPred ("$first_signal", 1, p_first_signal, SafePredFlag|SyncPredFlag);
   Yap_InitCPred ("$continue_signals", 0, p_continue_signals, SafePredFlag|SyncPredFlag);

H/Yap.h

@@ -394,7 +394,6 @@ typedef enum
   YAP_BREAK_SIGNAL = 0x2000,	/* received break signal */
   YAP_STACK_DUMP_SIGNAL = 0x4000,	/* received stack dump signal */
   YAP_STATISTICS_SIGNAL = 0x8000,	/* received statistics */
-  YAP_DELAY_CREEP_SIGNAL = 0x10000,	/* received a creep but should not do it */
   YAP_AGC_SIGNAL = 0x20000,	/* call atom garbage collector asap */
   YAP_PIPE_SIGNAL = 0x40000,	/* call atom garbage collector asap */
   YAP_VTALARM_SIGNAL = 0x80000,	/* received SIGVTALARM */

os/pl-file.c

@@ -5210,6 +5210,7 @@ init_yap(void)
 #endif
   initCharTypes();
   initPrologFlags();
+  clearPrologFlagMask(PLFLAG_DEBUGINFO);
   setPrologFlagMask(PLFLAG_TTY_CONTROL);
   initFiles();
   PL_register_extensions(PL_predicates_from_ctype);

pl/arith.yap

@@ -38,8 +38,10 @@ do_not_compile_expressions :- set_value('$c_arith',[]).
 
 '$do_c_built_in'(G, M, OUT) :- var(G), !,
 	'$do_c_built_metacall'(G, M, OUT).
-'$do_c_built_in'(Mod:G, _, OUT) :- !,
+'$do_c_built_in'(Mod:G, _, OUT) :- 
-	'$do_c_built_metacall'(G, Mod, OUT).
+	strip_module(Mod:G, M, G1),
+	var(G1), !,
+	'$do_c_built_metacall'(G1, M, OUT).
 '$do_c_built_in'(\+ G, _, OUT) :-
 	nonvar(G),
 	G = (A = B),
@@ -86,7 +88,6 @@ do_not_compile_expressions :- set_value('$c_arith',[]).
 	'$clean_cuts'(NG0, NG),
 	'$do_c_built_in'(A,M,NA).
 '$do_c_built_in'('C'(A,B,C), _, (A=[B|C])) :- !.
-'$do_c_built_in'(trace, _M, '$do_trace') :- !.
 '$do_c_built_in'(X is Y, M, P) :-
         primitive(X), !,
 	'$do_c_built_in'(X =:= Y, M, P).

pl/attributes.yap

@@ -148,7 +148,6 @@ lcall2([Goal|Goals], Mod) :-
 prolog:call_residue_vars(Goal,Residue) :-
 	attributes:all_attvars(Vs0),
 	call(Goal),
-	'$stop_creeping',
 	attributes:all_attvars(Vs),
 	% this should not be actually strictly necessary right now.
 	% but it makes it a safe bet.

pl/boot.yap

@@ -94,7 +94,6 @@ true :- true.
 	'$init_consult',
 	% '$swi_set_prolog_flag'(break_level, 0),
 	% '$set_read_error_handler'(error), let the user do that 
-	'$system_mode'(true),
 	nb_setval('$chr_toplevel_show_store',false).
 
 '$init_consult' :-
@@ -478,7 +477,7 @@ true :- true.
 	 (
 	  '$current_choice_point'(CP),
 	  '$current_module'(M),
-	  '$execute_outside_system_mode'(G, M),
+	  '$user_call'(G, M),
 	  '$current_choice_point'(NCP),
 	  '$delayed_goals'(G, V, NV, LGs, DCP),
 	  '$write_answer'(NV, LGs, Written),
@@ -542,7 +541,7 @@ true :- true.
 	!,
 	'$csult'([X|L], M).
 '$do_yes_no'(G, M) :-
-	'$execute_outside_system_mode'(G, M).
+	'$user_call'(G, M).
 
 '$write_query_answer_true'([]) :- !,
 	format(user_error,'true',[]).
@@ -750,6 +749,28 @@ incore(G) :- '$execute'(G).
 	'$current_choice_point'(CP),
 	'$call'(G, CP, G, M).
 
+'$user_call'(G, M) :-
+	 ( '$$save_by'(CP1),
+	 '$enable_debugging',
+	 '$call'(G, CP, M:G, M),
+	 '$$save_by'(CP2),
+	 (CP1 == CP2 -> ! ; ( true ; '$enable_debugging', fail ) ),
+	 '$disable_debugging'
+     ;
+	'$disable_debugging',
+	fail
+    ).
+
+'$enable_debugging' :-
+	'$swi_current_prolog_flag'(debug, false), !.
+'$enable_debugging' :-
+	'$nb_getval'('$trace', on, fail), !,
+	'$creep'.
+'$enable_debugging'.
+
+'$disable_debugging' :-
+	'$stop_creeping'.
+
 
 ','(X,Y) :-
 	yap_hacks:env_choice_point(CP),
@@ -1197,33 +1218,9 @@ catch_ball(C, C).
 	( call(user:H1) -> true ; true).
 '$run_toplevel_hooks'.
 
-'$enter_system_mode' :-
-	'$stop_creeping',
-	'$system_mode'(true).
-
-'$in_system_mode' :-
-	'$system_mode'(State),
-	State = true.
-
-'$execute_outside_system_mode'(G,M) :-
-	 ( '$$save_by'(CP1),
-	   '$exit_system_mode',
-	   '$call'(G, CP, M:G, M),
-	   '$$save_by'(CP2),
-	    (CP1 == CP2 -> ! ; ( true ; '$exit_system_mode', fail ) ),
-	   '$enter_system_mode'
-	;
-	  '$enter_system_mode',
-	  fail
-	).
-
-'$exit_system_mode' :-
-	'$system_mode'(false),
-	( '$nb_getval'('$trace',on,fail) -> '$meta_creep' ; true).
-
 '$run_at_thread_start' :-
 	recorded('$thread_initialization',M:D,_),
-	'$execute_outside_sysem_mode'(D, M),
+	'$meta_call'(D, M),
 	fail.
 '$run_at_thread_start'.
 

pl/consult.yap

@@ -336,7 +336,6 @@ use_module(M,F,Is) :-
 	% export to process
 	b_setval('$lf_status', TOpts),
 	'$reset_if'(OldIfLevel),
-	'$into_system_mode'(OldMode),
 	% take care with [a:f], a is the ContextModule
 	'$current_module'(SourceModule, ContextModule),
 	'$lf_opt'(consult, TOpts, Reconsult),
@@ -402,7 +401,6 @@ use_module(M,F,Is) :-
 	),
 	( LC == 0 -> prompt(_,'   |: ') ; true),
 	'$exec_initialisation_goals',
-        ( OldMode == true -> '$enter_system_mode' ; true ),
 %	format( 'O=~w~n', [Mod=UserFile] ),
 	!.
 
@@ -435,10 +433,6 @@ use_module(M,F,Is) :-
 	Level0 = Level.
 '$get_if'(0).
 
-'$into_system_mode'(OldMode) :-
-	'$system_mode'(OldMode),	
-	'$system_mode'(true).
-
 '$bind_module'(_, load_files).
 '$bind_module'(Mod, use_module(Mod)).
 
@@ -539,15 +533,12 @@ initialization(G,OPT) :-
 	        '$fetch_init_goal'(Level, G),
 		LGs),
 	lists:member(G,LGs),
-	'$nb_getval'('$system_mode', OldMode, fail),
-        ( OldMode == on -> '$exit_system_mode' ; true ),
 	% run initialization under user control (so allow debugging this stuff).
 	(
-	  '$system_catch'(once(M:G), M, Error, user:'$LoopError'(Error, top)),
+	  '$system_catch'(('$user_call'(G,M) -> true), M, Error, user:'$LoopError'(Error, top)),
 	  fail
 	;
           OldMode = on,
-	  '$enter_system_mode',
 	  fail
 	).
 '$exec_initialisation_goals' :-

pl/control.yap

@@ -119,7 +119,6 @@ setup_call_catcher_cleanup(Setup, Goal, Catcher, Cleanup) :-
 	 yap_hacks:enable_interrupts,
 	 '$current_choice_point'(CP0),
 	 '$execute'(Goal),
-         '$stop_creeping',
 	 '$current_choice_point'(CPF),
 	 (
 	  CP0 =:= CPF
@@ -130,7 +129,6 @@ setup_call_catcher_cleanup(Setup, Goal, Catcher, Cleanup) :-
 	  true
 	 )
 	;
-         '$stop_creeping',
 	 Catcher = fail,
 	 fail
 	).
@@ -266,7 +264,6 @@ b_getval(GlobalVariable, Val) :-
 
 break :-
 	'$init_debugger',
-	nb_getval('$system_mode',SystemMode),
 	nb_getval('$trace',Trace),
 	nb_setval('$trace',off),
 	nb_getval('$debug_jump',Jump),
@@ -291,8 +288,7 @@ break :-
 	nb_setval('$debug_jump',Jump),
 	nb_setval('$debug_run',Run),
 	nb_setval('$trace',Trace),
-	'$break'( false ),
+	'$break'( false ).
-	nb_setval('$system_mode',SystemMode).
 
 
 at_halt(G) :-

pl/debug.yap

@@ -186,15 +186,6 @@ trace :-
 	 '$init_debugger',
 	'$nb_getval'('$trace', on, fail), !.
 trace :-
-	nb_setval('$trace',on),
-	'$start_debugging'(on),
-	print_message(informational,debug(trace)),
-	'$meta_creep'.
-
-'$do_trace' :-
-	'$init_debugger',
-	'$nb_getval'('$trace', on, fail), !.
-'$do_trace' :-
 	nb_setval('$trace',on),
 	'$start_debugging'(on),
 	print_message(informational,debug(trace)),
@@ -310,13 +301,8 @@ debugging :-
 '$spy'([Mod|G]) :-
 	'$swi_current_prolog_flag'(debug, false), !,
 	'$execute_nonstop'(G,Mod).
-'$spy'([Mod|G]) :-
-	'$in_system_mode', !,
-	 '$exit_system_mode',
-	'$execute_nonstop'(G,Mod).
 '$spy'([Mod|G]) :-
 	CP is '$last_choice_pt',	
-	'$enter_system_mode',
 	'$do_spy'(G, Mod, CP, spy).
 
 % last argument to do_spy says that we are at the end of a context. It
@@ -437,7 +423,6 @@ debugging :-
 	    '$enter_goal'(GoalNumber, G, Module),
 	    '$spycall'(G, Module, CalledFromDebugger, Retry),
 	    % make sure we are in system mode when running the debugger.
-	    '$enter_system_mode',
 	    (
 	      '$debugger_deterministic_goal'(G) ->
 	      Det=true
@@ -463,7 +448,6 @@ debugging :-
 	      '$continue_debugging'(exit, CalledFromDebugger)	   
 	     ;
 	       % make sure we are in system mode when running the debugger.
-	       '$enter_system_mode',
 		/* backtracking from exit				*/
 	        /* we get here when we want to redo a goal		*/
 		/* redo port */
@@ -479,7 +463,6 @@ debugging :-
 	     fail			/* to backtrack to spycalls	*/
 	     )
 	  ;
-	    '$enter_system_mode',
 	    '$show_trace'(fail,G,Module,GoalNumber,_), /* inform at fail port		*/
 	    '$continue_debugging'(fail, CalledFromDebugger),
 	    /* fail port */
@@ -521,7 +504,6 @@ debugging :-
 '$spycall'(G, M, _, _) :-
 	nb_getval('$debug_jump',true),
 	!,
-	'$exit_system_mode',
 	'$execute_nonstop'(G,M).
 '$spycall'(G, M, _, _) :-
         (
@@ -533,7 +515,7 @@ debugging :-
 	(
 	   '$is_metapredicate'(G,M)
 	->
-	   '$meta_creep'(G,M)
+	   '$creep'(G,M)
 	;
 	    '$execute'(M:G)
 	).
@@ -564,17 +546,18 @@ debugging :-
 	 InRedo = true
 	).
 
-'$meta_creep'(G,M) :-
+%
+% execute a built-in in creep mode
+%
+'$creep'(G,M) :-
 	(
 	 '$$save_by'(CP1),
-	 '$exit_system_mode',
+	 '$creep',
-	 '$meta_creep',
 	 '$execute_nonstop'(G,M),
 	 '$$save_by'(CP2),
-	 (CP1 == CP2 -> ! ; ( true ; '$exit_system_mode', '$meta_creep', fail ) ),
+	 (CP1 == CP2 -> ! ; ( true ; '$creep', fail ) ),
-	 '$enter_system_mode'
+	  '$stop_creeping'
 	;
-	  '$enter_system_mode',
 	  fail
 	).
 
@@ -776,22 +759,11 @@ debugging :-
 '$continue_debugging'(_, debugger) :- !.
 % do not need to debug!
 % go back to original sequence.
-'$continue_debugging'(exit, meta_creep) :- !,
+'$continue_debugging'(zip, _) :- !.
-	 '$system_mode'(false),
-	'$meta_creep'.
-'$continue_debugging'(zip, _) :- !, '$exit_system_mode'.
-'$continue_debugging'(fail, creep) :- !,
-	'$system_mode'(false),
-	'$creep_fail'.
 '$continue_debugging'(_, creep) :- !,
-	'$creep',
-	'$system_mode'(false).
-'$continue_debugging'(fail, _) :- !.
-'$continue_debugging'(_, spy) :- !,
-	 '$system_mode'(false),
 	'$creep'.
-'$continue_debugging'(_, _) :-
+'$continue_debugging'(fail, _) :- !.
-	'$exit_system_mode'.
+'$continue_debugging'(_, _).
 
 % if we are in the interpreter, don't need to care about forcing a trace, do we?
 '$continue_debugging_goal'(yes,G) :- !,
@@ -805,10 +777,8 @@ debugging :-
 	'$execute_creep_dgoal'(G).
 	
 '$execute_dgoal'('$execute_nonstop'(G,M)) :-
-	 '$exit_system_mode',
 	 '$execute_nonstop'(G,M).
 '$execute_dgoal'('$execute_clause'(G, M, R, CP)) :-
-	 '$exit_system_mode',
 	 '$execute_clause'(G, M, R, CP).
 
 '$execute_creep_dgoal'('$execute_nonstop'(G,M)) :-

pl/init.yap

@@ -153,6 +153,9 @@ yap_hacks:cut_by(CP) :- '$$cut_by'(CP).
 
 :- '$change_type_of_char'(36,7). % Make $ a symbol character
 
+:-	'$swi_set_prolog_flag'(generate_debug_info,true).
+
+
 :- multifile user:library_directory/1.
 
 :- dynamic user:library_directory/1.

pl/setof.yap

@@ -50,11 +50,9 @@ findall(Template, Generator, Answers, SoFar) :-
 	nb:nb_queue(Ref),
 	(
 	  '$execute'(Generator),
-	 '$stop_creeping',
 	  nb:nb_queue_enqueue(Ref, Template),
 	 fail
 	;
-	 '$stop_creeping',
 	 nb:nb_queue_close(Ref, Answers, SoFar)
 	).
 
@@ -149,11 +147,9 @@ all(T,G,S) :-
 	'$init_db_queue'(Ref),
 	( '$catch'(Error,'$clean_findall'(Ref,Error),_),
 	  '$execute'(G),
-	  '$stop_creeping',
 	  '$db_enqueue'(Ref, T),
 	  fail
         ;
-	  '$stop_creeping',
 	  '$$set'(S,Ref)
         ).
 

pl/signals.yap

@@ -35,8 +35,6 @@
 % don't creep on meta-call.
 '$do_signal'(sig_creep, MG) :-
 	 '$start_creep'(MG, creep).
-'$do_signal'(sig_delay_creep, MG) :-
-	 '$start_creep'(MG, meta_creep).
 '$do_signal'(sig_iti, [M|G]) :-
 	'$thread_gfetch'(Goal),
 	% if more signals alive, set creep flag
@@ -92,9 +90,6 @@
 '$start_creep'([M|G], _) :-
 	'$is_no_trace'(G, M), !,
 	'$execute0'(G, M).
-'$start_creep'([Mod|G], _) :-
-	'$in_system_mode', !,
-	'$execute0'(G, Mod).
 '$start_creep'([Mod|G], WhereFrom) :-
 	CP is '$last_choice_pt',	
 	'$do_spy'(G, Mod, CP, WhereFrom).
@@ -202,8 +197,6 @@ read_sig.
 % make thes predicates non-traceable.
 
 :- '$set_no_trace'(true, prolog).
-:- '$set_no_trace'('$enter_system_mode', prolog).
-:- '$set_no_trace'('$do_trace', prolog).
 :- '$set_no_trace'('$call'(_,_,_,_), prolog).
 :- '$set_no_trace'('$execute_nonstop'(_,_), prolog).