yap-6.3/C/stack.c

/*************************************************************************
*									 *
*	 YAP Prolog 							 *
*									 *
*	Yap Prolog was developed at NCCUP - Universidade do Porto	 *
*									 *
* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997	 *
*									 *
**************************************************************************
*									 *
* File:		stack.c							 *
* comments:	Stack Introspection						 *
*									 *
* Last rev:     $Date: 2008-07-22 23:34:44 $,$Author: vsc $		 *
* $Log: not supported by cvs2svn $                                       *
* Revision 1.230  2008/06/02 17:20:28  vsc				 *
*									 *
*									 *
*************************************************************************/

/**
 * @file   stack.c
 * @author VITOR SANTOS COSTA <vsc@VITORs-MacBook-Pro.local>
 * @date   Tue Sep  8 23:33:02 2015
 * 
 * @brief  Get to know what is in your stack.
 * 
 * 
 */

#include "Yap.h"
#include "clause.h"
#include "yapio.h"
#include "eval.h"
#include "tracer.h"
#ifdef YAPOR
#include "or.macros.h"
#endif	/* YAPOR */
#ifdef TABLING
#include "tab.macros.h"
#endif /* TABLING */
#if HAVE_STRING_H
#include <string.h>
#endif
#include <heapgc.h>

#if !defined(YAPOR) && !defined(THREADS)
static void mark_pred(int, PredEntry *);
static void do_toggle_static_predicates_in_use(int);
#endif
static Int  in_use( USES_REGS1 );
static Int  PredForCode(yamop *, Atom *, arity_t *, Term *, PredEntry **);
static LogUpdIndex *find_owner_log_index(LogUpdIndex *, yamop *);
static StaticIndex *find_owner_static_index(StaticIndex *, yamop *);

#define IN_BLOCK(P,B,SZ)     ((CODEADDR)(P) >= (CODEADDR)(B) && \
			      (CODEADDR)(P) < (CODEADDR)(B)+(SZ))

static PredEntry *
get_pred(Term t,  Term tmod, char *pname)
{
  Term t0 = t;

 restart:
  if (IsVarTerm(t)) {
    Yap_Error(INSTANTIATION_ERROR, t0, pname);
    return NULL;
  } else if (IsAtomTerm(t)) {
    return RepPredProp(Yap_GetPredPropByAtom(AtomOfTerm(t), tmod));
  } else if (IsIntegerTerm(t) && tmod == IDB_MODULE) {
    return Yap_FindLUIntKey(IntegerOfTerm(t));
  } else if (IsApplTerm(t)) {
    Functor    fun = FunctorOfTerm(t);
    if (IsExtensionFunctor(fun)) {
      Yap_Error(TYPE_ERROR_CALLABLE, Yap_PredicateIndicator(t, tmod), pname);
      return NULL;
    }
    if (fun == FunctorModule) {
      Term tmod = ArgOfTerm(1, t);
      if (IsVarTerm(tmod) ) {
	Yap_Error(INSTANTIATION_ERROR, t0, pname);
	return NULL;
      }
      if (!IsAtomTerm(tmod) ) {
	Yap_Error(TYPE_ERROR_ATOM, t0, pname);
	return NULL;
      }
      t = ArgOfTerm(2, t);
      goto restart;
    }
    return RepPredProp(Yap_GetPredPropByFunc(fun, tmod));
  } else
    return NULL;
}


static PredEntry *
PredForChoicePt(yamop *p_code, op_numbers *opn) {
  while (TRUE) {
    op_numbers opnum;
    if (!p_code)
      return NULL;
    opnum = Yap_op_from_opcode(p_code->opc);
    if (opn)
        *opn = opnum;
    switch(opnum) {
    case _Nstop:
      return NULL;
    case _jump:
      p_code = p_code->y_u.l.l;
      break;
    case _retry_me:
    case _trust_me:
      return p_code->y_u.Otapl.p;
    case _retry_exo:
    case _retry_all_exo:
      return p_code->y_u.lp.p;
    case _try_logical:
    case _retry_logical:
    case _trust_logical:
    case _count_retry_logical:
    case _count_trust_logical:
    case _profiled_retry_logical:
    case _profiled_trust_logical:
      return p_code->y_u.OtaLl.d->ClPred;
#ifdef TABLING
    case _trie_trust_var:
    case _trie_retry_var:
    case _trie_trust_var_in_pair:
    case _trie_retry_var_in_pair:
    case _trie_trust_val:
    case _trie_retry_val:
    case _trie_trust_val_in_pair:
    case _trie_retry_val_in_pair:
    case _trie_trust_atom:
    case _trie_retry_atom:
    case _trie_trust_atom_in_pair:
    case _trie_retry_atom_in_pair:
    case _trie_trust_null:
    case _trie_retry_null:
    case _trie_trust_null_in_pair:
    case _trie_retry_null_in_pair:
    case _trie_trust_pair:
    case _trie_retry_pair:
    case _trie_trust_appl:
    case _trie_retry_appl:
    case _trie_trust_appl_in_pair:
    case _trie_retry_appl_in_pair:
    case _trie_trust_extension:
    case _trie_retry_extension:
    case _trie_trust_double:
    case _trie_retry_double:
    case _trie_trust_longint:
    case _trie_retry_longint:
    case _trie_trust_gterm:
    case _trie_retry_gterm:
      return NULL;
    case _table_load_answer:
    case _table_try_answer:
    case _table_answer_resolution:
    case _table_completion:
#ifdef THREADS_CONSUMER_SHARING
    case _table_answer_resolution_completion:
#endif /* THREADS_CONSUMER_SHARING */
      return NULL; /* ricroc: is this OK? */
      /* compile error --> return ENV_ToP(gc_B->cp_cp); */
#endif /* TABLING */
    case _or_else:
      if (p_code == p_code->y_u.Osblp.l) {
	/* repeat */
	Atom at = AtomRepeatSpace;
	return RepPredProp(PredPropByAtom(at, PROLOG_MODULE));
      } else {
	return p_code->y_u.Osblp.p0;
      }
      break;
    case _or_last:
#ifdef YAPOR
      return p_code->y_u.Osblp.p0;
#else
      return p_code->y_u.p.p;
#endif /* YAPOR */
      break;
    case _count_retry_me:
    case _retry_profiled:
    case _retry2:
    case _retry3:
    case _retry4:
      p_code = NEXTOP(p_code,l);
      break;
    default:
      return p_code->y_u.Otapl.p;
    }
  }
  return NULL;
}

/** 
 * Yap_PredForChoicePt(): find out the predicate who generated a CP.
 * 
 * @param cp the choice point
 * @param op the YAAM instruction to process next
 * 
 * @return A predixate structure or NULL
 *
 * usually pretty straightforward, it can fall in trouble with
 8 OR-P or tabling.
 */
PredEntry *
Yap_PredForChoicePt(choiceptr cp, op_numbers *op) {
  if (cp == NULL)
    return NULL;
  return PredForChoicePt(cp->cp_ap, op);
}

#if !defined(YAPOR) && !defined(THREADS)
static yamop *cur_clause(PredEntry *pe, yamop *codeptr)
{
  StaticClause *cl;

  cl = ClauseCodeToStaticClause(pe->cs.p_code.FirstClause);
  do {
    if (IN_BLOCK(codeptr,cl,cl->ClSize)) {
      return cl->ClCode;
    }
    if (cl->ClCode == pe->cs.p_code.LastClause)
      break;
    cl = cl->ClNext;
  } while (TRUE);
  Yap_Error(SYSTEM_ERROR_INTERNAL,TermNil,"could not find clause for indexing code");
  return(NULL);
}

static yamop *cur_log_upd_clause(PredEntry *pe, yamop *codeptr)
{
  LogUpdClause *cl;
  cl = ClauseCodeToLogUpdClause(pe->cs.p_code.FirstClause);
  do {
    if (IN_BLOCK(codeptr,cl->ClCode,cl->ClSize)) {
      return((yamop *)cl->ClCode);
    }
    cl = cl->ClNext;
  } while (cl != NULL);
  Yap_Error(SYSTEM_ERROR_INTERNAL,TermNil,"could not find clause for indexing code");
  return(NULL);
}

bool
Yap_search_for_static_predicate_in_use(PredEntry *p, bool check_everything)
{
  choiceptr b_ptr = B;
  CELL *env_ptr = ENV;

  if (check_everything && P) {
    PredEntry *pe = EnvPreg(P);
    if (p == pe) return true;
    pe = EnvPreg(CP);
    if (p == pe) return true;
  }
  do {
    PredEntry *pe;

    /* check first environments that are younger than our latest choicepoint */
    if (check_everything && env_ptr) {
      /*
	 I do not need to check environments for asserts,
	 only for retracts
      */
      while (env_ptr && b_ptr > (choiceptr)env_ptr) {
	yamop *cp = (yamop *)env_ptr[E_CP];
	PredEntry *pe;

	pe = EnvPreg(cp);
	if (p == pe) return true;
	if (env_ptr != NULL)
	  env_ptr = (CELL *)(env_ptr[E_E]);
      }
    }
    /* now mark the choicepoint */

    if (b_ptr)
      pe = PredForChoicePt(b_ptr->cp_ap, NULL);
    else
      return false;
    if (pe == p) {
      if (check_everything)
	return true;
      PELOCK(38,p);
      if (p->PredFlags & IndexedPredFlag) {
	yamop *code_p = b_ptr->cp_ap;
	yamop *code_beg = p->cs.p_code.TrueCodeOfPred;

	/* FIX ME */

	if (p->PredFlags & LogUpdatePredFlag) {
	  LogUpdIndex *cl = ClauseCodeToLogUpdIndex(code_beg);
	  if (find_owner_log_index(cl, code_p))
	    b_ptr->cp_ap = cur_log_upd_clause(pe, b_ptr->cp_ap->y_u.Otapl.d);
	} else if (p->PredFlags & MegaClausePredFlag) {
	  StaticIndex *cl = ClauseCodeToStaticIndex(code_beg);
	  if (find_owner_static_index(cl, code_p))
	    b_ptr->cp_ap = cur_clause(pe, b_ptr->cp_ap->y_u.Otapl.d);
	} else {
	  /* static clause */
	  StaticIndex *cl = ClauseCodeToStaticIndex(code_beg);
	  if (find_owner_static_index(cl, code_p)) {
	    b_ptr->cp_ap = cur_clause(pe, b_ptr->cp_ap->y_u.Otapl.d);
	  }
	}
      }
      UNLOCKPE(63,pe);
    }
    env_ptr = b_ptr->cp_env;
    b_ptr = b_ptr->cp_b;
  } while (b_ptr != NULL);
  return(FALSE);
}

static void
mark_pred(int mark, PredEntry *pe)
{
  /* if the predicate is static mark it */
  if (pe->ModuleOfPred) {
    PELOCK(39,p);
    if (mark) {
      pe->PredFlags |= InUsePredFlag;
    } else {
      pe->PredFlags &= ~InUsePredFlag;
    }
    UNLOCK(pe->PELock);
  }
}

/* go up the chain of choice_points and environments,
   marking all static predicates that current execution is depending
   upon */
static void
do_toggle_static_predicates_in_use(int mask)
{
  choiceptr b_ptr = B;
  CELL *env_ptr = ENV;

  if (b_ptr == NULL)
    return;

  do {
    PredEntry *pe;

    /* check first environments that are younger than our latest choicepoint */
    while (b_ptr > (choiceptr)env_ptr) {
      PredEntry *pe = EnvPreg((yamop *)env_ptr[E_CP]);

      mark_pred(mask, pe);
      env_ptr = (CELL *)(env_ptr[E_E]);
    }
    /* now mark the choicepoint */
    if ((b_ptr)) {
      if ((pe = PredForChoicePt(b_ptr->cp_ap, NULL))) {
	mark_pred(mask, pe);
      }
    }
    env_ptr = b_ptr->cp_env;
    b_ptr = b_ptr->cp_b;
  } while (b_ptr != NULL);
  /* mark or unmark all predicates */
  STATIC_PREDICATES_MARKED = mask;
}

static Int
toggle_static_predicates_in_use( USES_REGS1 )
{
#if !defined(YAPOR) && !defined(THREADS)
  Term t = Deref(ARG1);
  Int mask;

  /* find out whether we need to mark or unmark */
  if (IsVarTerm(t)) {
    Yap_Error(INSTANTIATION_ERROR,t,"toggle_static_predicates_in_use/1");
    return(FALSE);
  }
  if (!IsIntTerm(t)) {
    Yap_Error(TYPE_ERROR_INTEGER,t,"toggle_static_predicates_in_use/1");
    return(FALSE);
  }  else {
    mask = IntOfTerm(t);
  }
  do_toggle_static_predicates_in_use(mask);
#endif
  return TRUE;
}

#endif /* !defined(YAPOR) && !defined(THREADS) */

static void
clause_was_found(PredEntry *pp, Atom *pat, UInt *parity) { 
  if (pp->ModuleOfPred == IDB_MODULE) {
    if (pp->PredFlags & NumberDBPredFlag) {
      *parity = 0;
      *pat = AtomInteger;
    } else  if (pp->PredFlags & AtomDBPredFlag) {
      *parity = 0;
      *pat = (Atom)pp->FunctorOfPred;
    } else {
      *pat = NameOfFunctor(pp->FunctorOfPred);
      *parity = ArityOfFunctor(pp->FunctorOfPred);
    }
  } else {
    if (parity) {
      *parity = pp->ArityOfPE;
    }
    if (pat) {
      if (pp->ArityOfPE) {
        *pat = NameOfFunctor(pp->FunctorOfPred);
      } else {
        *pat = (Atom)(pp->FunctorOfPred);
      }
    }
  }
}

static void
code_in_pred_info(PredEntry *pp, Atom *pat, UInt *parity) {
  clause_was_found(pp, pat, parity);
}

static int
code_in_pred_lu_index(LogUpdIndex *icl, yamop *codeptr, void* *startp, void* *endp) {
  LogUpdIndex *cicl;
  if (IN_BLOCK(codeptr,icl,icl->ClSize)) {
    if (startp) *startp = (CODEADDR)icl;
    if (endp) *endp = (CODEADDR)icl+icl->ClSize;
    return TRUE;
  }
  cicl = icl->ChildIndex;
  while (cicl != NULL) {
    if (code_in_pred_lu_index(cicl, codeptr, startp, endp))
      return TRUE;
    cicl = cicl->SiblingIndex;
  }
  return FALSE;
}

static int
code_in_pred_s_index(StaticIndex *icl, yamop *codeptr, void* *startp, void* *endp) {
  StaticIndex *cicl;
  if (IN_BLOCK(codeptr,icl,icl->ClSize)) {
    if (startp) *startp = (CODEADDR)icl;
    if (endp) *endp = (CODEADDR)icl+icl->ClSize;
    return TRUE;
  }
  cicl = icl->ChildIndex;
  while (cicl != NULL) {
    if (code_in_pred_s_index(cicl, codeptr, startp, endp))
      return TRUE;
    cicl = cicl->SiblingIndex;
  }
  return FALSE;
}

static Int
find_code_in_clause(PredEntry *pp, yamop *codeptr, void **startp, void **endp) {
  Int i = 1;
  yamop *clcode;

  clcode = pp->cs.p_code.FirstClause;
  if (clcode != NULL) {
    if (pp->PredFlags & LogUpdatePredFlag) {
      LogUpdClause *cl = ClauseCodeToLogUpdClause(clcode);
      do {
	if (IN_BLOCK(codeptr,(CODEADDR)cl,cl->ClSize)) {
	  if (startp)
	    *startp = (CODEADDR)cl;
	  if (endp)
	    *endp = (CODEADDR)cl+cl->ClSize;
	  return i;
	}
	i++;
	cl = cl->ClNext;
      } while (cl != NULL);
    } else if (pp->PredFlags & DynamicPredFlag) {
      do {
	DynamicClause *cl;
	
	cl = ClauseCodeToDynamicClause(clcode);
	if (IN_BLOCK(codeptr,cl,cl->ClSize)) {
	  if (startp)
	    *startp = (CODEADDR)cl;
	  if (endp)
	    *endp = (CODEADDR)cl+cl->ClSize;
	  return i;
	}
	if (clcode == pp->cs.p_code.LastClause)
	  break;
	i++;
	clcode = NextDynamicClause(clcode);
      } while (TRUE);
    } else if (pp->PredFlags & MegaClausePredFlag) {
      MegaClause *cl;
	
      cl = ClauseCodeToMegaClause(clcode);
      if (IN_BLOCK(codeptr,cl,cl->ClSize)) {
	  if (startp)
	    *startp = (CODEADDR)cl;
	  if (endp)
	    *endp = (CODEADDR)cl+cl->ClSize;
	return 1+((char *)codeptr-(char *)cl->ClCode)/cl->ClItemSize;
      }
    } else {
      StaticClause *cl;
	
      cl = ClauseCodeToStaticClause(clcode);
      do {
	if (IN_BLOCK(codeptr,cl,cl->ClSize)) {
	  if (startp)
	    *startp = (CODEADDR)cl;
	  if (endp)
	    *endp = (CODEADDR)cl+cl->ClSize;
	  return i;
	}
	if (cl->ClCode == pp->cs.p_code.LastClause)
	  break;
	i++;
	cl = cl->ClNext;
      } while (TRUE);
    }
  }
  return(0);
}

static Term
clause_loc(void *clcode, PredEntry *pp) {

  CACHE_REGS
  if (pp->PredFlags & LogUpdatePredFlag) {
    LogUpdClause *cl = ClauseCodeToLogUpdClause(clcode);
      cl = ClauseCodeToLogUpdClause(clcode);
	
      if (cl->ClFlags & FactMask) {
	return  MkIntegerTerm(cl->lusl.ClLine);
      } else {
	return MkIntegerTerm(cl->lusl.ClSource->ag.line_number);
      }
  } else if (pp->PredFlags & DynamicPredFlag) {
	DynamicClause *cl;
      cl = ClauseCodeToDynamicClause(clcode);
	
      return TermNil;
  } else if (pp->PredFlags & MegaClausePredFlag) {
     MegaClause *mcl = ClauseCodeToMegaClause(pp->cs.p_code.FirstClause);
     return MkIntTerm(mcl->ClLine);	
    } else {
      StaticClause *cl;
      cl = ClauseCodeToStaticClause(clcode);
	
      if (cl->ClFlags & FactMask) {
	return  MkIntTerm(cl->usc.ClLine);
      } else if (cl->ClFlags & SrcMask) {
	return MkIntTerm(cl->usc.ClSource->ag.line_number);
      } else
	return TermNil;
	
  }
  return TermNil;
}

static int
cl_code_in_pred(PredEntry *pp, yamop *codeptr, void* *startp, void* *endp) {
  Int out;

  PELOCK(39,pp);
  /* check if the codeptr comes from the indexing code */
  if (pp->PredFlags & IndexedPredFlag) {
    if (pp->PredFlags & LogUpdatePredFlag) {
      if (code_in_pred_lu_index(ClauseCodeToLogUpdIndex(pp->cs.p_code.TrueCodeOfPred), codeptr, startp, endp)) {
	UNLOCK(pp->PELock);
	return TRUE;
      }
    } else {
      if (code_in_pred_s_index(ClauseCodeToStaticIndex(pp->cs.p_code.TrueCodeOfPred), codeptr, startp, endp)) {
	UNLOCK(pp->PELock);
	return TRUE;
      }
    }
  }
  if (pp->PredFlags & (CPredFlag|AsmPredFlag|UserCPredFlag)) {
    StaticClause *cl = ClauseCodeToStaticClause(pp->CodeOfPred);
    if (IN_BLOCK(codeptr,(CODEADDR)cl,cl->ClSize)) {
      if (startp)
	*startp = (CODEADDR)cl;
      if (endp)
	*endp = (CODEADDR)cl+cl->ClSize;
      UNLOCK(pp->PELock);
      return TRUE;
    } else {
      UNLOCK(pp->PELock);
      return FALSE;
    }
  } else {
    out = find_code_in_clause(pp, codeptr, startp, endp);
  }
  UNLOCK(pp->PELock); 
  if (out) return TRUE;
  return FALSE;
}

static Int
code_in_pred(PredEntry *pp, Atom *pat, UInt *parity, yamop *codeptr) {
  Int out;

  PELOCK(40,pp);
  /* check if the codeptr comes from the indexing code */
  if (pp->PredFlags & IndexedPredFlag) {
    if (pp->PredFlags & LogUpdatePredFlag) {
      if (code_in_pred_lu_index(ClauseCodeToLogUpdIndex(pp->cs.p_code.TrueCodeOfPred), codeptr, NULL, NULL)) {
	code_in_pred_info(pp, pat, parity);
	UNLOCK(pp->PELock);
	return -1;
      }
    } else {
      if (code_in_pred_s_index(ClauseCodeToStaticIndex(pp->cs.p_code.TrueCodeOfPred), codeptr, NULL, NULL)) {
	code_in_pred_info(pp, pat, parity);
	UNLOCK(pp->PELock);
	return -1;
      }
    }
  }
  if ((out = find_code_in_clause(pp, codeptr, NULL, NULL))) {
    clause_was_found(pp, pat, parity);
  }
  UNLOCK(pp->PELock); 
  return out;
}

static Int
PredForCode(yamop *codeptr, Atom *pat, UInt *parity, Term *pmodule, PredEntry **pep) {
  Int found = 0;
  ModEntry *me = CurrentModules;

  /* should we allow the user to see hidden predicates? */
  while (me) {

    PredEntry *pp;
    pp = me->PredForME;
    while (pp != NULL) {
      if ((found = code_in_pred(pp,  pat, parity, codeptr)) != 0) {
        if (pmodule)
          *pmodule = MkAtomTerm(me->AtomOfME);
        if (pep)
          *pep = pp;
        return found;
      }
      pp = pp->NextPredOfModule;
    }
    me = me->NextME;
  }
  return(0);
}

Int
Yap_PredForCode(yamop *codeptr, find_pred_type where_from, Atom *pat, UInt *parity, Term *pmodule) {
  PredEntry *p;

  if (where_from == FIND_PRED_FROM_CP) {
    p = PredForChoicePt(codeptr, NULL);
  } else if (where_from == FIND_PRED_FROM_ENV) {
    p = EnvPreg(codeptr);
    if (p) {
      Int out;
      if (p->ModuleOfPred == PROLOG_MODULE)
	*pmodule = TermProlog;
      else
	*pmodule = p->ModuleOfPred;
      out = find_code_in_clause(p, codeptr, NULL, NULL); 
      clause_was_found(p, pat, parity);
      return out;
    }
  } else {
    return PredForCode(codeptr, pat, parity, pmodule, NULL);
  }
  if (p == NULL) {
    return 0;
  }
  clause_was_found(p, pat, parity);
  if (p->ModuleOfPred == PROLOG_MODULE)
    *pmodule = TermProlog;
  else
    *pmodule = p->ModuleOfPred;
  return -1;
}

/* intruction blocks we found ourselves at */
static PredEntry *
walk_got_lu_block(LogUpdIndex *cl, void* *startp, void* *endp)
{
  PredEntry *pp = cl->ClPred;
  *startp = (CODEADDR)cl;
  *endp = (CODEADDR)cl+cl->ClSize;
  return pp;
}

/* intruction blocks we found ourselves at */
static PredEntry *
walk_got_lu_clause(LogUpdClause *cl, void* *startp, void* *endp)
{
  *startp = (CODEADDR)cl;
  *endp = (CODEADDR)cl+cl->ClSize;
  return cl->ClPred;
}

/* we hit a meta-call, so we don't know what is happening */
static PredEntry *
found_meta_call(void* *startp, void* *endp)
{
  PredEntry *pp = PredMetaCall;
  *startp = (CODEADDR)&(pp->OpcodeOfPred);
  *endp = (CODEADDR)NEXTOP((yamop *)&(pp->OpcodeOfPred),e);
  return pp;
}

/* intruction blocks we found ourselves at */
static PredEntry *
walk_found_c_pred(PredEntry *pp, void* *startp, void* *endp)
{
  StaticClause  *cl = ClauseCodeToStaticClause(pp->CodeOfPred);
  *startp = (CODEADDR)&(cl->ClCode);
  *endp = (CODEADDR)&(cl->ClCode)+cl->ClSize;
  return pp;
}

/* we hit a mega-clause, no point in going on */
static PredEntry *
found_mega_clause(PredEntry *pp, void* *startp, void* *endp)
{
  MegaClause *mcl = ClauseCodeToMegaClause(pp->cs.p_code.FirstClause);
  *startp = (CODEADDR)mcl;
  *endp = (CODEADDR)mcl+mcl->ClSize;
  return pp;
}

/* we hit a mega-clause, no point in going on */
static PredEntry *
found_idb_clause(yamop *pc, void* *startp, void* *endp)
{
  LogUpdClause *cl = ClauseCodeToLogUpdClause(pc);

  *startp = (CODEADDR)cl;
  *endp = (CODEADDR)cl+cl->ClSize;
  return cl->ClPred;
}

/* we hit a expand_index, no point in going on */
static PredEntry *
found_expand_index(yamop *pc, void* *startp, void* *endp, yamop *codeptr USES_REGS)
{
  PredEntry *pp = codeptr->y_u.sssllp.p;
  if (pc == codeptr) {
    *startp = (CODEADDR)codeptr;
    *endp = (CODEADDR)NEXTOP(codeptr,sssllp);
  }
  return pp;
}

/* we hit a expand_index, no point in going on */
static PredEntry *
found_fail(yamop *pc, void* *startp, void* *endp USES_REGS)
{
  PredEntry *pp = RepPredProp(Yap_GetPredPropByAtom(AtomFail,CurrentModule));
  *startp = *endp = (CODEADDR)FAILCODE;
  return pp;
}

/* we hit a expand_index, no point in going on */
static PredEntry *
found_owner_op(yamop *pc, void* *startp, void* *endp USES_REGS)
{
  PredEntry *pp = ((PredEntry *)(Unsigned(pc)-(CELL)(&(((PredEntry *)NULL)->OpcodeOfPred))));
  *startp = (CODEADDR)&(pp->OpcodeOfPred);
  *endp = (CODEADDR)NEXTOP((yamop *)&(pp->OpcodeOfPred),e);
  return pp;
}

/* we hit a expand_index, no point in going on */
static PredEntry *
found_expand(yamop *pc, void* *startp, void* *endp USES_REGS)
{
  PredEntry *pp = ((PredEntry *)(Unsigned(pc)-(CELL)(&(((PredEntry *)NULL)->cs.p_code.ExpandCode))));
  *startp = (CODEADDR)&(pp->cs.p_code.ExpandCode);
  *endp = (CODEADDR)NEXTOP((yamop *)&(pp->cs.p_code.ExpandCode),e);
  return pp;
}

static PredEntry *
found_ystop(yamop *pc, int clause_code, void* *startp, void* *endp, PredEntry *pp USES_REGS)
{
  if (pc == YESCODE) {
    pp = RepPredProp(Yap_GetPredPropByAtom(AtomTrue,CurrentModule));
    *startp = (CODEADDR)YESCODE;
    *endp = (CODEADDR)YESCODE+(CELL)(NEXTOP((yamop *)NULL,e));
    return pp;
  }
  if (!pp) {
    /* must be an index */
    PredEntry **pep = (PredEntry **)pc->y_u.l.l;
    pp = pep[-1];
  }
  if (pp->PredFlags & LogUpdatePredFlag) {
    if (clause_code) {
      LogUpdClause *cl = ClauseCodeToLogUpdClause(pc->y_u.l.l);
      *startp = (CODEADDR)cl;
      *endp = (CODEADDR)cl+cl->ClSize;
    } else {
      LogUpdIndex *cl = ClauseCodeToLogUpdIndex(pc->y_u.l.l);
      *startp = (CODEADDR)cl;
      *endp = (CODEADDR)cl+cl->ClSize;
    }
  } else if (pp->PredFlags & DynamicPredFlag) {
    DynamicClause *cl = ClauseCodeToDynamicClause(pc->y_u.l.l);
    *startp = (CODEADDR)cl;
    *endp = (CODEADDR)cl+cl->ClSize;
  } else {
    if (clause_code) {
      StaticClause *cl = ClauseCodeToStaticClause(pc->y_u.l.l);
      *startp = (CODEADDR)cl;
      *endp = (CODEADDR)cl+cl->ClSize;
    } else {
      StaticIndex *cl = ClauseCodeToStaticIndex(pc->y_u.l.l);
      *startp = (CODEADDR)cl;
      *endp = (CODEADDR)cl+cl->ClSize;
    }
  }
  return pp;
}

static PredEntry *
ClauseInfoForCode(yamop *codeptr, void* *startp, void* *endp USES_REGS) {
  yamop *pc;
  PredEntry *pp = NULL;
  int clause_code = FALSE;

  if (codeptr >= COMMA_CODE &&
	codeptr < FAILCODE) {
    pp = RepPredProp(Yap_GetPredPropByFunc(FunctorComma,CurrentModule));
    *startp = (CODEADDR)COMMA_CODE;
    *endp = (CODEADDR)(FAILCODE-1);
    return pp;
  }
  pc = codeptr;
#include "walkclause.h"
  return NULL;
}

PredEntry *
Yap_PredEntryForCode(yamop *codeptr, find_pred_type where_from, void* *startp, void* *endp) {
  CACHE_REGS
  if (where_from == FIND_PRED_FROM_CP) {
    PredEntry *pp = PredForChoicePt(codeptr, NULL);
    if (cl_code_in_pred(pp, codeptr, startp, endp)) {
      return pp;
    }
  } else if (where_from == FIND_PRED_FROM_ENV) {
    PredEntry *pp = EnvPreg(codeptr);
    if (cl_code_in_pred(pp, codeptr, startp, endp)) {
      return pp;
    }
  } else {
    return ClauseInfoForCode(codeptr, startp, endp PASS_REGS);
  }
  return NULL;
}




/** 
 * Detect whether the predicate describing the goal in A1,
 * module A2 is currently live in the stack. 
 * 
 * @param USES_REGS1 
 * 
 * @return liveness
 */
static Int
in_use( USES_REGS1 )
{				/* '$in_use'(+P,+Mod)	 */
  PredEntry      *pe;
  Int            out;

  pe = get_pred(Deref(ARG1),  Deref(ARG2), "$in_use");
  if (EndOfPAEntr(pe))
    return FALSE;
  PELOCK(25,pe);
  out = Yap_static_in_use(pe,TRUE);
  UNLOCKPE(42,pe);
  return(out);
}


static Int
pred_for_code( USES_REGS1 ) {
  yamop *codeptr;
  Atom at;
  arity_t arity;
  Term tmodule = TermProlog;
  Int cl;
  Term t = Deref(ARG1);

  if (IsVarTerm(t)) {
    return FALSE;
  } else if (IsApplTerm(t) && FunctorOfTerm(t) == FunctorStaticClause) {
    codeptr  = Yap_ClauseFromTerm(t)->ClCode;
  } else if (IsIntegerTerm(t)) {
    codeptr  = (yamop *)IntegerOfTerm(t);
  } else if (IsDBRefTerm(t)) {
    codeptr  = (yamop *)DBRefOfTerm(t);
  } else {
    return FALSE;
  }
  cl = PredForCode(codeptr, &at, &arity, &tmodule, NULL);
  if (!tmodule) tmodule = TermProlog;
  if (cl == 0) {
    return Yap_unify(ARG5,MkIntTerm(0));
  } else {
    return(Yap_unify(ARG2,MkAtomTerm(at)) &&
	   Yap_unify(ARG3,MkIntegerTerm(arity)) &&
	   Yap_unify(ARG4,tmodule) &&
	   Yap_unify(ARG5,MkIntegerTerm(cl)));
  }
}

static LogUpdIndex *
find_owner_log_index(LogUpdIndex *cl, yamop *code_p)
{
  yamop *code_beg = cl->ClCode;
  yamop *code_end = (yamop *)((char *)cl + cl->ClSize);

  if (code_p >= code_beg && code_p <= code_end) {
    return cl;
  }
  cl = cl->ChildIndex;
  while (cl != NULL) {
    LogUpdIndex *out;
    if ((out = find_owner_log_index(cl, code_p)) != NULL) {
      return out;
    }
    cl = cl->SiblingIndex;
  }
  return NULL;
}

static StaticIndex *
find_owner_static_index(StaticIndex *cl, yamop *code_p)
{
  yamop *code_beg = cl->ClCode;
  yamop *code_end = (yamop *)((char *)cl + cl->ClSize);

  if (code_p >= code_beg && code_p <= code_end) {
    return cl;
  }
  cl = cl->ChildIndex;
  while (cl != NULL) {
    StaticIndex *out;
    if ((out = find_owner_static_index(cl, code_p)) != NULL) {
      return out;
    }
    cl = cl->SiblingIndex;
  }
  return NULL;
}

ClauseUnion *
Yap_find_owner_index(yamop *ipc, PredEntry *ap)
{
  /* we assume we have an owner index */
  if (ap->PredFlags & LogUpdatePredFlag) {
    LogUpdIndex *cl = ClauseCodeToLogUpdIndex(ap->cs.p_code.TrueCodeOfPred);
    return (ClauseUnion *)find_owner_log_index(cl,ipc);
  } else {
    StaticIndex *cl = ClauseCodeToStaticIndex(ap->cs.p_code.TrueCodeOfPred);
    return (ClauseUnion *)find_owner_static_index(cl,ipc);
  }
}

static Term
all_envs(CELL *env_ptr USES_REGS)
{
  Term tf = AbsPair(HR);
  CELL *start = HR;
  CELL *bp = NULL;
  
  /* walk the environment chain */
  while (env_ptr) {
    bp = HR;
    HR += 2;
    /* notice that MkIntegerTerm may increase the HReap */
    bp[0] = MkIntegerTerm(LCL0-env_ptr);
    if (HR >= ASP-1024) {
      HR = start;
      LOCAL_Error_Size = (ASP-1024)-HR;
      while (env_ptr) {
	LOCAL_Error_Size += 2;
	env_ptr = (CELL *)(env_ptr[E_E]);      
      }
      return 0L;
    } else {
      bp[1] = AbsPair(HR);
    }
    env_ptr = (CELL *)(env_ptr[E_E]);      
  }
  bp[1] = TermNil;
  return tf;
}

static Term
all_cps(choiceptr b_ptr USES_REGS)
{
  CELL *bp = NULL;
  CELL *start = HR;
  Term tf = AbsPair(HR);

  while (b_ptr) {
    bp = HR;
    HR += 2;
    /* notice that MkIntegerTerm may increase the HReap */
    bp[0] = MkIntegerTerm((Int)(LCL0-(CELL *)b_ptr));
    if (HR >= ASP-1024) {
      HR = start;
      LOCAL_Error_Size = (ASP-1024)-HR;
      while (b_ptr) {
	LOCAL_Error_Size += 2;
	b_ptr = b_ptr->cp_b;
      }
      return 0L;
    } else {
      bp[1] = AbsPair(HR);
    }
    b_ptr = b_ptr->cp_b;
  }
  bp[1] = TermNil;
  return tf;
}



static Int
p_all_choicepoints( USES_REGS1 )
{
  Term t;
  while ((t = all_cps(B PASS_REGS)) == 0L) {
    if (!Yap_gcl(LOCAL_Error_Size, 1, ENV, gc_P(P,CP))) {
      Yap_Error(RESOURCE_ERROR_STACK, TermNil, "while dumping choicepoints");
      return FALSE;
    }
  }
  return Yap_unify(ARG1,t);
}

static Int
p_all_envs( USES_REGS1 )
{
  Term t;
  while ((t = all_envs(ENV PASS_REGS)) == 0L) {
    if (!Yap_gcl(LOCAL_Error_Size, 1, ENV, gc_P(P,CP))) {
      Yap_Error(RESOURCE_ERROR_STACK, TermNil, "while dumping environments");
      return FALSE;
    }
  }
  return Yap_unify(ARG1,t);
}

 Term
clause_info ( yamop *codeptr, PredEntry *pp) {
   CACHE_REGS
  Term ts[2];
  void *begin;

  if (pp->ArityOfPE == 0) {
    ts[0] = MkAtomTerm((Atom)pp->FunctorOfPred);
    ts[1] = MkIntTerm(0);
  } else {
    ts[0] = MkAtomTerm(NameOfFunctor( pp->FunctorOfPred));
    ts[1] = MkIntegerTerm(pp->ArityOfPE);
  }
  
  ts[0] = MkAtomTerm(pp->src.OwnerFile);
  Term t1 = Yap_MkApplTerm( FunctorModule, 2, ts);
  if (find_code_in_clause(pp, codeptr, &begin, NULL) <=  0 ||
      ((ts[0] = clause_loc(begin, pp) == TermNil ))) { 
    ts[0] = clause_loc(pp->cs.p_code.FirstClause, pp);
    ts[1] = clause_loc(pp->cs.p_code.LastClause, pp);
    if (ts[0] == ts[1] && ts[1] != TermNil)
      {}
    else if (ts[1]== TermNil && ts[0] != TermNil)
      ts[0] = Yap_MkApplTerm( FunctorMinus, 2, ts);
  }
  ts[1] = t1;
  return Yap_MkApplTerm( FunctorModule, 2, ts );
}







static Term
error_culprit(bool internal USES_REGS)
{
  PredEntry *pe;
  // case number 1: Yap_Error called from built-in.
  if (internal) {
    pe = EnvPreg(CP);
    if (pe->PredFlags & HiddenPredFlag) return clause_info(P, pe);
  } else {
    CELL * curENV = ENV;
    yamop *curCP = CP;
    PredEntry *pe = EnvPreg(curCP);

    while (curCP != YESCODE) {
      if (pe->ModuleOfPred) return clause_info(P, pe);
      curENV = (CELL *)(curENV[E_E]);
      curCP = (yamop *)(curENV[E_CP]);
      pe = EnvPreg(curCP);
    }
  }
  return TermNil;
}

static Term
all_calls( bool internal USES_REGS )
{
  Term ts[6];
  Functor f = Yap_MkFunctor(AtomLocalSp,6);

  // The first argument is key: it tries to
  // catch the culprit at the user level,
  ts[0] = error_culprit(internal PASS_REGS);
  ts[1] = MkAddressTerm(P);
  ts[2] = MkAddressTerm(CP);
  ts[3] = MkAddressTerm(PP);
  if (trueLocalPrologFlag(STACK_DUMP_ON_ERROR_FLAG)) {
    ts[4] = all_envs(ENV PASS_REGS);
    ts[5] = all_cps(B PASS_REGS);
    if (ts[4] == 0L ||
        ts[5] == 0L)
      return 0L;
  } else {
    ts[4] = ts[5] = TermNil;
  }
  return Yap_MkApplTerm(f,6,ts);
}

/** 
 * report the current status of the stacks up to level $N$
 * 
 * @param depth 
 * 
 * @return data on the current program counter 
 */

Term
 Yap_all_calls( void )
{
  CACHE_REGS
  return all_calls( true PASS_REGS );
}


static Int
current_stack( USES_REGS1 )
{
  Term t;
  while ((t = all_calls( false PASS_REGS)) == 0L) {
    if (!Yap_gcl(LOCAL_Error_Size, 1, ENV, gc_P(P,CP))) {
      Yap_Error(RESOURCE_ERROR_STACK, TermNil, "while dumping stack");
      return FALSE;
    }
  }
  return Yap_unify(ARG1,t);
}


#if LOW_PROF

static void
add_code_in_lu_index(LogUpdIndex *cl, PredEntry *pp)
{
  char *code_end = (char *)cl + cl->ClSize;
  Yap_inform_profiler_of_clause(cl, code_end, pp, GPROF_LU_INDEX);
  cl = cl->ChildIndex;
  while (cl != NULL) {
    add_code_in_lu_index(cl, pp);
    cl = cl->SiblingIndex;
  }
}

static void
add_code_in_static_index(StaticIndex *cl, PredEntry *pp)
{
  char *code_end = (char *)cl + cl->ClSize;
  Yap_inform_profiler_of_clause(cl, code_end, pp, GPROF_STATIC_INDEX);
  cl = cl->ChildIndex;
  while (cl != NULL) {
    add_code_in_static_index(cl, pp);
    cl = cl->SiblingIndex;
  }
}


static void
add_code_in_pred(PredEntry *pp) {
  yamop *clcode;

  PELOCK(49,pp);
  /* check if the codeptr comes from the indexing code */

  /* highly likely this is used for indexing */
  Yap_inform_profiler_of_clause(&(pp->OpcodeOfPred), &(pp->OpcodeOfPred)+1, pp, GPROF_INIT_OPCODE);
  if (pp->PredFlags & (CPredFlag|AsmPredFlag)) {
    char *code_end;
    StaticClause *cl;

    clcode = pp->CodeOfPred;
    cl = ClauseCodeToStaticClause(clcode);
    code_end = (char *)cl + cl->ClSize;
    Yap_inform_profiler_of_clause(cl, code_end, pp, GPROF_INIT_SYSTEM_CODE);
    UNLOCK(pp->PELock);
    return;
  }
  Yap_inform_profiler_of_clause(&(pp->cs.p_code.ExpandCode), &(pp->cs.p_code.ExpandCode)+1, pp, GPROF_INIT_EXPAND);
  clcode = pp->cs.p_code.TrueCodeOfPred;
  if (pp->PredFlags & IndexedPredFlag) {
    if (pp->PredFlags & LogUpdatePredFlag) {
      LogUpdIndex *cl = ClauseCodeToLogUpdIndex(clcode);
      add_code_in_lu_index(cl, pp);
    } else {
      StaticIndex *cl = ClauseCodeToStaticIndex(clcode);
      add_code_in_static_index(cl, pp);
    }
  }
  clcode = pp->cs.p_code.FirstClause;
  if (clcode != NULL) {
    if (pp->PredFlags & LogUpdatePredFlag) {
      LogUpdClause *cl = ClauseCodeToLogUpdClause(clcode);
      do {
	char *code_end;

	code_end = (char *)cl + cl->ClSize;
	Yap_inform_profiler_of_clause(cl, code_end, pp, GPROF_INIT_LOG_UPD_CLAUSE);
	cl = cl->ClNext;
      } while (cl != NULL);
    } else if (pp->PredFlags & DynamicPredFlag) {
      do {
	DynamicClause *cl;
	CODEADDR code_end;

	cl = ClauseCodeToDynamicClause(clcode);
 	code_end = (CODEADDR)cl + cl->ClSize;
	Yap_inform_profiler_of_clause(cl, code_end, pp, GPROF_INIT_DYNAMIC_CLAUSE);
	if (clcode == pp->cs.p_code.LastClause)
	  break;
	clcode = NextDynamicClause(clcode);
      } while (TRUE);
    } else {
      StaticClause *cl = ClauseCodeToStaticClause(clcode);
      do {
	char *code_end;

	code_end = (char *)cl + cl->ClSize;
	Yap_inform_profiler_of_clause(cl, code_end, pp,GPROF_INIT_STATIC_CLAUSE);
	if (cl->ClCode == pp->cs.p_code.LastClause)
	  break;
	cl = cl->ClNext;
      } while (TRUE);
    }
  }
  UNLOCK(pp->PELock);
}


void
Yap_dump_code_area_for_profiler(void) {
  ModEntry *me = CurrentModules;

  while (me) {
    PredEntry *pp = me->PredForME;

    while (pp != NULL) {
      /*      if (pp->ArityOfPE) {
	fprintf(stderr,"%s/%d %p\n",
		RepAtom(NameOfFunctor(pp->FunctorOfPred))->StrOfAE,
		pp->ArityOfPE,
		pp);
      } else {
	fprintf(stderr,"%s %p\n",
		RepAtom((Atom)(pp->FunctorOfPred))->StrOfAE,
		pp);
		}*/
      add_code_in_pred(pp);
      pp = pp->NextPredOfModule;
    }
    me = me->NextME;
  }
  Yap_inform_profiler_of_clause(COMMA_CODE, FAILCODE, RepPredProp(Yap_GetPredPropByFunc(FunctorComma,0)), GPROF_INIT_COMMA);
  Yap_inform_profiler_of_clause(FAILCODE, FAILCODE+1, RepPredProp(Yap_GetPredPropByAtom(AtomFail,0)), GPROF_INIT_FAIL);
}

#endif /* LOW_PROF */


static Int
program_continuation( USES_REGS1 )
{
  PredEntry *pe = EnvPreg((yamop *)((ENV_Parent(ENV))[E_CP]));
  if (pe->ModuleOfPred) {
    if (!Yap_unify(ARG1,pe->ModuleOfPred))
      return FALSE;
  } else {
    if (!Yap_unify(ARG1,TermProlog))
      return FALSE;
  }
  if (pe->ArityOfPE) {
    if (!Yap_unify(ARG2,MkAtomTerm(NameOfFunctor(pe->FunctorOfPred))))
      return FALSE;
    if (!Yap_unify(ARG3,MkIntegerTerm(ArityOfFunctor(pe->FunctorOfPred))))
      return FALSE;
  } else {
    if (!Yap_unify(ARG2,MkAtomTerm((Atom)pe->FunctorOfPred)))
      return FALSE;
    if (!Yap_unify(ARG3,MkIntTerm(0)))
      return FALSE;
  }
  return TRUE;
}

static Term
BuildActivePred(PredEntry *ap, CELL *vect)
{
  CACHE_REGS
  arity_t i;

  if (!ap->ArityOfPE) {
    return MkVarTerm();
  }
  for (i = 0; i < ap->ArityOfPE; i++) {
    Term t = Deref(vect[i]);
    if (IsVarTerm(t)) {
      CELL *pt = VarOfTerm(t);
      /* one stack */
      if (pt > HR) {
	Term nt = MkVarTerm();
	Yap_unify(t, nt);
      }
    }
  }
  return Yap_MkApplTerm(ap->FunctorOfPred, ap->ArityOfPE, vect);
}

static int
UnifyPredInfo(PredEntry *pe, int start_arg USES_REGS) {
  arity_t arity = pe->ArityOfPE;
  Term tmod, tname;

  if (pe->ModuleOfPred != IDB_MODULE) {
    if (pe->ModuleOfPred == PROLOG_MODULE) {
      tmod = TermProlog;
    } else {
      tmod = pe->ModuleOfPred;
    }
    if (pe->ArityOfPE == 0) {
      tname = MkAtomTerm((Atom)pe->FunctorOfPred);
    } else {
      Functor f = pe->FunctorOfPred;
      tname = MkAtomTerm(NameOfFunctor(f));
    }
  } else {
    tmod = pe->ModuleOfPred;
    if (pe->PredFlags & NumberDBPredFlag) {
      tname = MkIntegerTerm(pe->src.IndxId);
    } else if (pe->PredFlags & AtomDBPredFlag) {
      tname = MkAtomTerm((Atom)pe->FunctorOfPred);
    } else {
      Functor f = pe->FunctorOfPred;
      tname = MkAtomTerm(NameOfFunctor(f));
    }
  }

  return Yap_unify(XREGS[start_arg], tmod) &&
    Yap_unify(XREGS[start_arg+1],tname) &&
    Yap_unify(XREGS[start_arg+2],MkIntegerTerm(arity));
}


static Int
ClauseId(yamop *ipc, PredEntry *pe)
{
  if (!ipc)
    return 0;
  return find_code_in_clause(pe, ipc, NULL, NULL);
}

static Int
env_info( USES_REGS1 )
{
  CELL *env = LCL0-IntegerOfTerm(Deref(ARG1));
  yamop *env_cp;
  Term env_b, taddr;

  if (!env)
    return FALSE;
  env_b = MkIntegerTerm((Int)(LCL0-(CELL *)env[E_CB]));
  env_cp = (yamop *)env[E_CP];

  /* pe = PREVOP(env_cp,Osbpp)->y_u.Osbpp.p0; */
  taddr = MkIntegerTerm((Int)env);
  return Yap_unify(ARG3,MkIntegerTerm((Int)env_cp)) &&
    Yap_unify(ARG2, taddr) &&
    Yap_unify(ARG4, env_b);
}

static Int
p_cpc_info( USES_REGS1 )
{
  PredEntry *pe;
  yamop *ipc = (yamop *)IntegerOfTerm(Deref(ARG1));

  pe = PREVOP(ipc,Osbpp)->y_u.Osbpp.p0;
  return UnifyPredInfo(pe, 2 PASS_REGS) &&
    Yap_unify(ARG5,MkIntegerTerm(ClauseId(ipc,pe)));
}

static Int
p_choicepoint_info( USES_REGS1 )
{
  choiceptr cptr = (choiceptr)(LCL0-IntegerOfTerm(Deref(ARG1)));
  PredEntry *pe = NULL;
  int go_on = TRUE;
  yamop *ipc = cptr->cp_ap;
  yamop *ncl = NULL;
  Term t = TermNil, taddr;

  taddr = MkIntegerTerm((Int)cptr);
  while (go_on) {
    op_numbers opnum = Yap_op_from_opcode(ipc->opc);
    go_on = FALSE;
    switch (opnum) {
#ifdef TABLING
    case _table_load_answer:
#ifdef LOW_LEVEL_TRACER
      pe = LOAD_CP(cptr)->cp_pred_entry;
#else
      pe = UndefCode;
#endif
      t = MkVarTerm();
      break;
    case _table_try_answer:
    case _table_retry_me:
    case _table_trust_me:
    case _table_retry:
    case _table_trust:
    case _table_completion:
#ifdef THREADS_CONSUMER_SHARING
    case _table_answer_resolution_completion:
#endif /* THREADS_CONSUMER_SHARING */
#ifdef LOW_LEVEL_TRACER
#ifdef DETERMINISTIC_TABLING
      if (IS_DET_GEN_CP(cptr)) {
	pe = DET_GEN_CP(cptr)->cp_pred_entry;
	t = MkVarTerm();
      } else
#endif /* DETERMINISTIC_TABLING */
      {
	pe = GEN_CP(cptr)->cp_pred_entry;
	t = BuildActivePred(pe, (CELL *)(GEN_CP(B) + 1));
      }
#else
      pe = UndefCode;
      t = MkVarTerm();
#endif
      break;
    case _table_answer_resolution:
#ifdef LOW_LEVEL_TRACER
      pe = CONS_CP(cptr)->cp_pred_entry;
#else
      pe = UndefCode;
#endif
      t = MkVarTerm();
      break;
    case _trie_trust_var:
    case _trie_retry_var:
    case _trie_trust_var_in_pair:
    case _trie_retry_var_in_pair:
    case _trie_trust_val:
    case _trie_retry_val:
    case _trie_trust_val_in_pair:
    case _trie_retry_val_in_pair:
    case _trie_trust_atom:
    case _trie_retry_atom:
    case _trie_trust_atom_in_pair:
    case _trie_retry_atom_in_pair:
    case _trie_trust_null:
    case _trie_retry_null:
    case _trie_trust_null_in_pair:
    case _trie_retry_null_in_pair:
    case _trie_trust_pair:
    case _trie_retry_pair:
    case _trie_trust_appl:
    case _trie_retry_appl:
    case _trie_trust_appl_in_pair:
    case _trie_retry_appl_in_pair:
    case _trie_trust_extension:
    case _trie_retry_extension:
    case _trie_trust_double:
    case _trie_retry_double:
    case _trie_trust_longint:
    case _trie_retry_longint:
    case _trie_trust_gterm:
    case _trie_retry_gterm:
      pe = UndefCode;
      t = MkVarTerm();
      break;
#endif /* TABLING */
    case _try_logical:
    case _retry_logical:
    case _trust_logical:
    case _count_retry_logical:
    case _count_trust_logical:
    case _profiled_retry_logical:
    case _profiled_trust_logical:
      ncl = ipc->y_u.OtaLl.d->ClCode;
      pe = ipc->y_u.OtaLl.d->ClPred;
      t = BuildActivePred(pe, cptr->cp_args);
      break;
    case _or_else:
      pe = ipc->y_u.Osblp.p0;
      ncl = ipc;
      t = Yap_MkNewApplTerm(FunctorOr, 2);
      break;

    case _or_last:
#ifdef YAPOR
      pe = ipc->y_u.Osblp.p0;
#else
      pe = ipc->y_u.p.p;
#endif
      ncl = ipc;
      t = Yap_MkNewApplTerm(FunctorOr, 2);
      break;
    case _retry2:
    case _retry3:
    case _retry4:
      pe = NULL;
      t = TermNil;
      ipc = NEXTOP(ipc,l);
      if (!ncl)
	ncl = ipc->y_u.Otapl.d;
      go_on = TRUE;
      break;
    case _jump:
      pe = NULL;
      t = TermNil;
      ipc = ipc->y_u.l.l;
      go_on = TRUE;
      break;
    case _retry_c:
    case _retry_userc:
      ncl = NEXTOP(ipc,OtapFs);
      pe = ipc->y_u.OtapFs.p;
      t = BuildActivePred(pe, cptr->cp_args);
      break;
    case _retry_profiled:
    case _count_retry:
      pe = NULL;
      t = TermNil;
      ncl = ipc->y_u.Otapl.d;
      ipc = NEXTOP(ipc,p);
      go_on = TRUE;
      break;
    case _retry_me:
    case _trust_me:
    case _count_retry_me:
    case _count_trust_me:
    case _profiled_retry_me:
    case _profiled_trust_me:
    case _retry_and_mark:
    case _profiled_retry_and_mark:
    case _retry:
    case _trust:
      if (!ncl)
	ncl = ipc->y_u.Otapl.d;
      pe = ipc->y_u.Otapl.p;
      t = BuildActivePred(pe, cptr->cp_args);
      break;
    case _retry_exo:
    case _retry_all_exo:
      ncl = NULL;
      pe = ipc->y_u.lp.p;
      t = BuildActivePred(pe, cptr->cp_args);
      break;
    case _Nstop:
      {
	Atom at = AtomLive;
	t = MkAtomTerm(at);
	pe = RepPredProp(PredPropByAtom(at, CurrentModule));
      }
      break;
    case _Ystop:
    default:
      return FALSE;
    }
  }
  return UnifyPredInfo(pe, 3 PASS_REGS) &&
    Yap_unify(ARG2, taddr) &&
    Yap_unify(ARG6,t) &&
    Yap_unify(ARG7,MkIntegerTerm(ClauseId(ncl,pe)));
}

static Int			/* $parent_pred(Module, Name, Arity) */
parent_pred( USES_REGS1 )
{
  /* This predicate is called from the debugger.
     We assume a sequence of the form a -> b */
  Atom at;
  arity_t arity;
  Term module;
  if (!PredForCode(P_before_spy, &at, &arity, &module, NULL)) {
    return Yap_unify(ARG1, MkIntTerm(0)) &&
	   Yap_unify(ARG2, MkAtomTerm(AtomMetaCall)) &&
	   Yap_unify(ARG3, MkIntTerm(0));
  }  
  return Yap_unify(ARG1, MkIntTerm(module)) &&
	 Yap_unify(ARG2, MkAtomTerm(at)) &&
	 Yap_unify(ARG3, MkIntTerm(arity));
}

void Yap_dump_stack( void );
void DumpActiveGoals( CACHE_TYPE1 );
static int hidden(Atom);
static int legal_env(CELL * CACHE_TYPE);

#define ONLOCAL(ptr) (CellPtr(ptr) > CellPtr(HR)  && CellPtr(ptr) < CellPtr(LOCAL_LocalBase))

static int
hidden (Atom at)
{
  AtomEntry *chain;

  READ_LOCK(INVISIBLECHAIN.AERWLock);
  chain = RepAtom(INVISIBLECHAIN.Entry);
  while (!EndOfPAEntr (chain) && AbsAtom (chain) != at)
    chain = RepAtom(chain->NextOfAE);
  READ_UNLOCK(INVISIBLECHAIN.AERWLock);
  if (EndOfPAEntr (chain))
    return (FALSE);
  return (TRUE);
}

static int
legal_env (CELL *ep USES_REGS)
{
  CELL cp, ps;
  PredEntry *pe;
  if (!ONLOCAL (ep) || Unsigned (ep) & 3)
    return (FALSE);
  cp = ep[E_CP];
  if (!ONHEAP (cp))
    return (FALSE);
  ps = *((CELL *) (Addr (cp) - CellSize));
  pe = (PredEntry *) (ps - sizeof (OPREG) - sizeof (Prop));
  PELOCK(70,pe);
  if (!ONHEAP (pe) || Unsigned (pe) & 3 || pe->KindOfPE & 0xff00) {
    UNLOCK(pe->PELock);
    return (FALSE);
  }
  UNLOCK(pe->PELock);
  return (TRUE);
}

static bool
handled_exception( USES_REGS1 )
{
 yamop *pos = NEXTOP(PredDollarCatch->cs.p_code.TrueCodeOfPred,l);
 bool found_handler = false;
 choiceptr gc_b;

 gc_b = B;
 while (gc_b) {
   yamop *ap = gc_b->cp_ap;
   if (ap == NOCODE) {
     /* C-code: let they deal with that */
     return false;
   } else if (ap == pos) {
     if (found_handler)
       return TRUE; /* we have two handlers */
     found_handler = true;
   }
   gc_b = gc_b->cp_b;
 }
 /* handled by Top c-code? */
 return !found_handler;
}



void
Yap_dump_stack( void )
{
  CACHE_REGS
  choiceptr b_ptr = B;
  CELL *env_ptr = ENV;
  char tp[256];
  yamop *ipc = CP;
  int max_count = 200;

  /* check if handled */
  if (handled_exception( PASS_REGS1 ))
    return;
#if DEBUG
  fprintf(stderr,"%% YAP regs: P=%p, CP=%p, ASP=%p, H=%p, TR=%p, HeapTop=%p\n",P,CP,ASP,HR,TR,HeapTop);
  fprintf(stderr,"%% YAP mode: %ux\n",(unsigned int)LOCAL_PrologMode);
  if (LOCAL_ErrorMessage)
    fprintf(stderr,"%% LOCAL_ErrorMessage: %s\n",LOCAL_ErrorMessage);
#endif
  if (HR > ASP || HR > LCL0) {
    fprintf(stderr,"%% YAP ERROR: Global Collided against Local (%p--%p)\n",HR,ASP);
  } else   if (HeapTop > (ADDR)LOCAL_GlobalBase) {
    fprintf(stderr,"%% YAP ERROR: Code Space Collided against Global (%p--%p)\n", HeapTop, LOCAL_GlobalBase);
  } else {
#if !USE_SYSTEM_MALLOC
    fprintf (stderr,"%ldKB of Code Space (%p--%p)\n",(long int)((CELL)HeapTop-(CELL)Yap_HeapBase)/1024,Yap_HeapBase,HeapTop);
#if USE_DL_MALLOC
    if (Yap_NOfMemoryHoles) {
      UInt i;

      for (i=0; i < Yap_NOfMemoryHoles; i++)
        fprintf(stderr,"  Current hole: %p--%p\n",
                Yap_MemoryHoles[i].start,
                Yap_MemoryHoles[i].end);
    }
#endif
#endif
    Yap_detect_bug_location(P, FIND_PRED_FROM_ANYWHERE, (char *)HR, 256);
    fprintf (stderr,"%%\n%% PC: %s\n",(char *)HR);
    Yap_detect_bug_location(CP, FIND_PRED_FROM_ANYWHERE, (char *)HR, 256);
    fprintf (stderr,"%%   Continuation: %s\n",(char *)HR);
    fprintf (stderr,"%%    %luKB of Global Stack (%p--%p)\n",(unsigned long int)(sizeof(CELL)*(HR-H0))/1024,H0,HR);
    fprintf (stderr,"%%    %luKB of Local Stack (%p--%p)\n",(unsigned long int)(sizeof(CELL)*(LCL0-ASP))/1024,ASP,LCL0);
    fprintf (stderr,"%%    %luKB of Trail (%p--%p)\n",(unsigned long int)((ADDR)TR-LOCAL_TrailBase)/1024,LOCAL_TrailBase,TR);
    fprintf (stderr,"%%    Performed %ld garbage collections\n", (unsigned long int)LOCAL_GcCalls);
#if LOW_LEVEL_TRACER
    {
      extern long long vsc_count;

      if (vsc_count) {
#if _WIN32
        fprintf(stderr,"Trace Counter at %I64d\n",vsc_count);
#else
        fprintf(stderr,"Trace Counter at %lld\n",vsc_count);
#endif
      }
    }
#endif
    fprintf (stderr,"%% All Active Calls and\n");
    fprintf (stderr,"%%         Goals With Alternatives Open  (Global In Use--Local In Use)\n%%\n");
    while (b_ptr != NULL) {
      while (env_ptr && env_ptr <= (CELL *)b_ptr) {
        Yap_detect_bug_location(ipc, FIND_PRED_FROM_ENV, tp, 256);
        if (env_ptr == (CELL *)b_ptr &&
            (choiceptr)env_ptr[E_CB] > b_ptr) {
          b_ptr = b_ptr->cp_b;
          fprintf(stderr,"%%  %s\n", tp);
        } else {
          fprintf(stderr,"%%  %s\n", tp);
        }
        if (!max_count--) {
          fprintf(stderr,"%%  .....\n");
          return;
        }
        ipc = (yamop *)(env_ptr[E_CP]);
        env_ptr = (CELL *)(env_ptr[E_E]);
      }
      if (b_ptr) {
        if (!max_count--) {
          fprintf(stderr,"%%  .....\n");
          return;
        }
        if (b_ptr->cp_ap && /* tabling */
            b_ptr->cp_ap->opc != Yap_opcode(_or_else) &&
            b_ptr->cp_ap->opc != Yap_opcode(_or_last) &&
            b_ptr->cp_ap->opc != Yap_opcode(_Nstop)) {
          /* we can safely ignore ; because there is always an upper env */
          Yap_detect_bug_location(b_ptr->cp_ap, FIND_PRED_FROM_CP, tp, 256);
          fprintf(stderr,"%%         %s (%luKB--%luKB)\n", tp,
                  (unsigned long int)((b_ptr->cp_h-H0)*sizeof(CELL)/1024),
                  (unsigned long int)((ADDR)LCL0-(ADDR)b_ptr)/1024);
        }
        b_ptr = b_ptr->cp_b;
      }
    }
  }
}

void
DumpActiveGoals ( USES_REGS1 )
{
  /* try to dump active goals */
  CELL *ep = YENV;		/* and current environment		  */
  choiceptr b_ptr = B;
  CELL cp;
  PredEntry *pe;
  int first = 1;

  if (legal_env (YENV PASS_REGS) && YENV < ENV)
    ep = YENV;
  else if (legal_env (ENV PASS_REGS))
    ep = ENV;
  while (TRUE)
    {
      if (!ONLOCAL (ep) || (Unsigned (ep) & (sizeof(CELL)-1)))
        break;
      cp = ep[E_CP];
      if (!ONHEAP (cp) || (Unsigned (cp) & (sizeof(CELL)-1)))
        break;
      pe = EnvPreg((yamop *)cp);
      if (!ONHEAP (pe) || Unsigned (pe) & (sizeof(CELL)-1))
        break;
      PELOCK(71,pe);
      if (pe->KindOfPE & 0xff00) {
        UNLOCK(pe->PELock);
        break;
      }
      if (pe->PredFlags & (CompiledPredFlag | DynamicPredFlag))
        {
          Functor f;

	  UNLOCK(pe->PELock);
	  f = pe->FunctorOfPred;
	  if (pe->KindOfPE && hidden (NameOfFunctor (f)))
	    goto next;
	  if (first++ == 1)
	    fprintf(stderr,"Active ancestors:\n");
	  Yap_DebugWriteIndicator(pe);
	  Yap_DebugPutc (stderr,'\n');
	} else {
	  UNLOCK(pe->PELock);
	}
    next:
      ep = (CELL *) ep[E_E];
    }
  first = 1;
  fprintf(stderr,"Active Choice-Points:\n");
  while (TRUE)
    {
      PredEntry *pe;
      op_numbers opnum;
      if (!ONLOCAL (b_ptr) || b_ptr->cp_b == NULL)
        break;
      fprintf(stderr,"%p ", b_ptr);
      pe = Yap_PredForChoicePt(b_ptr, &opnum);
      if (opnum == _Nstop) {
        fprintf(stderr, "  ********** C-Code Interface Boundary ***********\n");
      } else {
        Functor f;
        Term mod = PROLOG_MODULE;

	f = pe->FunctorOfPred;
	if (pe->ModuleOfPred)
	  mod = pe->ModuleOfPred;
	else mod = TermProlog;
	if (mod != TermProlog &&
	    mod != MkAtomTerm(AtomUser) ) {
	  Yap_DebugPlWrite (mod);
	  Yap_DebugPutc (stderr,':');
	}
	if (mod == IDB_MODULE) {
	  if (pe->PredFlags & NumberDBPredFlag) {
	    Int id = pe->src.IndxId;
	    Yap_DebugPlWrite(MkIntegerTerm(id));
	  } else if (pe->PredFlags & AtomDBPredFlag) {
	    Atom At = (Atom)pe->FunctorOfPred;
	    Yap_DebugPlWrite(MkAtomTerm(At));
	  } else {
	    Functor f = pe->FunctorOfPred;
	    Atom At = NameOfFunctor(f);
	    arity_t arity = ArityOfFunctor(f);
	    int i;

	    Yap_DebugPlWrite(MkAtomTerm(At));
	    Yap_DebugPutc (stderr,'(');
	    for (i= 0; i < arity; i++) {
	      if (i > 0) Yap_DebugPutc (stderr,',');
	      Yap_DebugPutc (stderr,'_');
	    }
	    Yap_DebugPutc (stderr,')');
	  }
	  Yap_DebugPutc (stderr,'(');
	  Yap_DebugPlWrite(b_ptr->cp_a2);
	  Yap_DebugPutc (stderr,')');
	} else if (pe->ArityOfPE == 0) {
	  Yap_DebugPlWrite (MkAtomTerm ((Atom)f));
	} else {
	  Int i = 0, arity = pe->ArityOfPE;
	  if (opnum == _or_last||
	      opnum == _or_else) {
	    Yap_DebugPlWrite (MkAtomTerm (NameOfFunctor (f)));
	    Yap_DebugPutc (stderr,'(');
	    for (i= 0; i < arity; i++) {
	      if (i > 0) Yap_DebugPutc (stderr,',');
	      Yap_DebugPutc(stderr, '_');
	    }
	    Yap_DebugErrorPuts (") :- ... ( _  ; _ ");
	  } else {
	    Term *args = &(b_ptr->cp_a1);
	    Yap_DebugPlWrite (MkAtomTerm (NameOfFunctor (f)));
	    Yap_DebugPutc (stderr,'(');
	    for (i= 0; i < arity; i++) {
	      if (i > 0) Yap_DebugPutc (stderr,',');
	      Yap_DebugPlWrite(args[i]);
	    }
	  }
	  Yap_DebugPutc (stderr,')');
	}
	Yap_DebugPutc (stderr,'\n');
      }
      b_ptr = b_ptr->cp_b;
    }
}


void
Yap_detect_bug_location(yamop *yap_pc, int where_from, char *tp, int psize)
{
 Atom pred_name;
  UInt pred_arity;
  Term pred_module;
  Int cl;

  tp[0] = '\0';
  if ((cl = Yap_PredForCode(yap_pc, where_from, &pred_name, &pred_arity, &pred_module))
      == 0) {
    /* system predicate */
#if   HAVE_SNPRINTF
    snprintf(tp, psize, "%s",
             "meta-call");
#else
    sprintf(tp, "%s",
            "meta-call");
#endif
  } else if (pred_module == 0) {
    /* don't give info on system predicates */
#if   HAVE_SNPRINTF
    snprintf(tp, psize, "prolog:%s/%lu",
             RepAtom(pred_name)->StrOfAE, (unsigned long int)pred_arity);
#else
    sprintf(tp, "in prolog:%s/%lu",
            RepAtom(pred_name)->StrOfAE, (unsigned long int)pred_arity);
#endif
  } else if (cl < 0) {
#if   HAVE_SNPRINTF
    snprintf(tp, psize, "%s:%s/%lu",
             RepAtom(AtomOfTerm(pred_module))->StrOfAE,
             RepAtom(pred_name)->StrOfAE, (unsigned long int)pred_arity);
#else
    sprintf(tp, "%s:%s/%lu",
            RepAtom(AtomOfTerm(pred_module))->StrOfAE,
            RepAtom(pred_name)->StrOfAE, (unsigned long int)pred_arity);
#endif
  } else {
#if   HAVE_SNPRINTF
    snprintf(tp, psize, "%s:%s/%lu at clause %lu ",
             RepAtom(AtomOfTerm(pred_module))->StrOfAE,
             RepAtom(pred_name)->StrOfAE, (unsigned long int)pred_arity, (unsigned long int)cl);
#else
    sprintf(tp, "%s:%s/%lu at clause %lu",
            RepAtom(AtomOfTerm(pred_module))->StrOfAE,
            RepAtom(pred_name)->StrOfAE, (unsigned long int)pred_arity, (unsigned long int)cl);
#endif
  }
}

static Term
build_bug_location( yamop *codeptr, PredEntry *pe)
{
  CACHE_REGS
  Term p[5];
  if (pe->ModuleOfPred == PROLOG_MODULE)
	p[0] = TermProlog;
      else
	p[0] = pe->ModuleOfPred;
      if (pe->ArityOfPE)
	p[1] = MkAtomTerm(NameOfFunctor(pe->FunctorOfPred));
      else
	p[1] = MkAtomTerm((Atom)pe->FunctorOfPred);
      p[2] = MkIntegerTerm( pe->ArityOfPE );
      if (pe->src.OwnerFile) {
	p[3] = MkAtomTerm(pe->src.OwnerFile);
	if (pe->PredFlags & MegaClausePredFlag) {
	  MegaClause *mcl;
	  mcl =
	    ClauseCodeToMegaClause(pe->cs.p_code.FirstClause);
	  p[4] = MkIntegerTerm( mcl->ClLine );
	} else {
	  void *clcode;
	  if ( find_code_in_clause( pe, codeptr, &clcode, NULL) > 0 ) {
	    if (pe->PredFlags & LogUpdatePredFlag) {
	      LogUpdClause *cl = clcode;
	    	
	      if (cl->ClFlags & FactMask) {
		p[4] =  MkIntegerTerm(cl->lusl.ClLine);
	      } else {
		p[4] = MkIntegerTerm(cl->lusl.ClSource->ag.line_number);
	      }
	    } else if (pe->PredFlags & DynamicPredFlag) {
	
	      p[4] = MkIntTerm(0);
	    } else {
	      StaticClause *cl;
	      cl = clcode;
	      
	      if (cl->ClFlags & FactMask) {
		p[4] =  MkIntTerm(cl->usc.ClLine);
	      } else if (cl->ClFlags & SrcMask) {
		p[4] =  MkIntTerm(cl->usc.ClSource->ag.line_number);
	      } else
		p[4] = MkIntTerm(0);
	    }
	  }
	} 
      } else if (pe->OpcodeOfPred == UNDEF_OPCODE) {
	RESET_VARIABLE(p+3);
	RESET_VARIABLE(p+4);
      } else {
	// by default, user_input
	p[3] = MkAtomTerm(AtomUserIn);
	p[4] = MkIntTerm(0);
      }
      return Yap_MkApplTerm( Yap_MkFunctor(Yap_LookupAtom("p"), 5), 5, p);
}


Term
Yap_pc_location(yamop *pc, choiceptr b_ptr, CELL *env)
{
  CACHE_REGS
  yamop *codeptr = pc;
  PredEntry *pe;
  if (PP == NULL) {
    if(PredForCode(pc, NULL, NULL, NULL, &pe) < 0)
      return TermNil;
  } else
    pe = PP;
  if (pe != NULL
      //pe->ModuleOfPred != PROLOG_MODULE &&
      // &&!(pe->PredFlags & HiddenPredFlag)
      ) {
    return build_bug_location( codeptr, pe );
  }
  return TermNil;
}


Term
Yap_env_location( yamop *cp, choiceptr b_ptr, CELL *env, Int ignore_first)
{
  while ( true ) {
    if (b_ptr == NULL || env == NULL)
      return TermNil;
    PredEntry *pe= EnvPreg(cp);
      if (ignore_first <= 0 && pe
	  //pe->ModuleOfPred != PROLOG_MODULE &&s
          &&  !(pe->PredFlags & HiddenPredFlag)
          ) {
	return build_bug_location( cp, pe );
      } else {
	if (b_ptr && b_ptr->cp_env < env) {
	  cp = b_ptr->cp_cp;
	  env = b_ptr->cp_env;
	  b_ptr = b_ptr->cp_b;
	} else {
	  cp = (yamop *)env[E_CP];
	  env = ENV_Parent(env);
	}
        ignore_first--;
    }
  }
}

static Int
clause_location( USES_REGS1 )
{
  return Yap_unify(Yap_pc_location(P, B, ENV), ARG1) &&
  Yap_unify(Yap_env_location(CP, B, ENV, 1), ARG2);
}

static Int
ancestor_location( USES_REGS1 )
{
  return
  Yap_unify(Yap_env_location(CP, B, ENV, 2), ARG1) &&
  Yap_unify(Yap_env_location(CP, B, ENV, 3), ARG2);
}


void
Yap_InitStInfo(void)
{
  CACHE_REGS
  Term cm = CurrentModule;

  Yap_InitCPred("in_use", 2, in_use, HiddenPredFlag|TestPredFlag | SafePredFlag|SyncPredFlag);
#ifndef THREADS
  Yap_InitCPred("toggle_static_predicates_in_use", 0, toggle_static_predicates_in_use, HiddenPredFlag|SafePredFlag|SyncPredFlag);
#endif
  CurrentModule = HACKS_MODULE;
  Yap_InitCPred("current_choicepoints", 1, p_all_choicepoints, 0);
  Yap_InitCPred("current_continuations", 1, p_all_envs, 0);
  Yap_InitCPred("choicepoint", 7, p_choicepoint_info, 0);
  Yap_InitCPred("continuation", 4, env_info,0);
  Yap_InitCPred("cp_to_predicate", 5, p_cpc_info, 0);
  CurrentModule = cm;
  Yap_InitCPred("current_stack", 1, current_stack, HiddenPredFlag);
  Yap_InitCPred("pred_for_code", 5, pred_for_code, HiddenPredFlag);
  Yap_InitCPred("parent_pred", 3, parent_pred, HiddenPredFlag|SafePredFlag);
  Yap_InitCPred("program_continuation", 3, program_continuation, HiddenPredFlag|SafePredFlag);
  Yap_InitCPred("clause_location", 2, clause_location, HiddenPredFlag|SafePredFlag);
  Yap_InitCPred("ancestor_location", 2, ancestor_location, HiddenPredFlag|SafePredFlag);


}