diff --git a/C/absmi.c b/C/absmi.c
index 91a616ea5..bda98daec 100644
--- a/C/absmi.c
+++ b/C/absmi.c
@@ -1197,13 +1197,15 @@ Yap_absmi(int inp)
 	    FAIL();
 	  }
 	}
-	setregs();
 	if (!Yap_IUnify(ARG2, t)) {
+	  setregs();
 	  FAIL();
 	}
 	if (!Yap_IUnify(ARG3, MkDBRefTerm((DBRef)cl))) {
+	  setregs();
 	  FAIL();
 	}
+	setregs();
 
 #if defined(YAPOR) || defined(THREADS)
 
@@ -1237,12 +1239,16 @@ Yap_absmi(int inp)
       {
 	LogUpdClause *cl = ClauseCodeToLogUpdClause(PREG);
 
+	saveregs();
 	if (!Yap_IUnify(ARG2, cl->ClSource->Entry)) {
+	  setregs();
 	  FAIL();
 	}
 	if (!Yap_IUnify(ARG3, MkDBRefTerm((DBRef)cl))) {
+	  setregs();
 	  FAIL();
 	}
+	setregs();
 
 	/* say that an environment is using this clause */
 	/* we have our own copy for the clause */
diff --git a/C/alloc.c b/C/alloc.c
index 51f258123..04ea548f0 100644
--- a/C/alloc.c
+++ b/C/alloc.c
@@ -12,7 +12,7 @@
 * Last rev:								 *
 * mods:									 *
 * comments:	allocating space					 *
-* version:$Id: alloc.c,v 1.38 2003-10-30 11:31:05 vsc Exp $		 *
+* version:$Id: alloc.c,v 1.39 2003-10-30 22:52:46 vsc Exp $		 *
 *************************************************************************/
 #ifdef SCCS
 static char SccsId[] = "%W% %G%";
@@ -1113,16 +1113,22 @@ Yap_InitMemory(int Trail, int Heap, int Stack)
 int
 Yap_ExtendWorkSpace(Int s)
 {
+#if USE_MMAP
   return ExtendWorkSpace(s, MAP_FIXED);
+#else
+  return ExtendWorkSpace(s);
+#endif
 }
 
 UInt
 Yap_ExtendWorkSpaceThroughHole(UInt s)
 {
+#if USE_MMAP
   MALLOC_T WorkSpaceTop0 = WorkSpaceTop;
 
   if (ExtendWorkSpace(s, 0))
     return WorkSpaceTop-WorkSpaceTop0;
+#endif
   return -1;
 }
 
diff --git a/C/index.c b/C/index.c
index ff37fabd5..5c7f2982e 100644
--- a/C/index.c
+++ b/C/index.c
@@ -4609,6 +4609,7 @@ cp_lu_trychain(yamop *codep, yamop *ocodep, yamop *ostart, int flag, PredEntry *
 {
   int count_reds = ap->PredFlags & CountPredFlag;
   int profiled = ap->PredFlags & ProfiledPredFlag;
+  int compact_mode = (codep == ocodep);
 
   while (ocodep != NULL &&
 	 ocodep < ostart->u.Ill.l2) {
@@ -4624,7 +4625,8 @@ cp_lu_trychain(yamop *codep, yamop *ocodep, yamop *ostart, int flag, PredEntry *
       if (i == 0) {
 	if (op != _try_clause) {
 	  LogUpdClause *tgl = ClauseCodeToLogUpdClause(ocodep->u.ld.d);
-	  tgl->ClRefCount--;
+	  if (compact_mode)
+	    tgl->ClRefCount--;
 	}
 	codep->opc = Yap_opcode(_try_clause);
 	codep = copy_ld(codep, ocodep, ap, ocodep->u.ld.d, FALSE);
@@ -4632,6 +4634,9 @@ cp_lu_trychain(yamop *codep, yamop *ocodep, yamop *ostart, int flag, PredEntry *
 	if (op == _try_clause) {
 	  LogUpdClause *tgl = ClauseCodeToLogUpdClause(ocodep->u.ld.d);
 	  tgl->ClRefCount++;
+	} else if (!compact_mode) {
+	  LogUpdClause *tgl = ClauseCodeToLogUpdClause(ocodep->u.ld.d);
+	  tgl->ClRefCount++;
 	}
 	codep = gen_lui_retry(codep, ocodep, profiled, count_reds, ap);
       }
@@ -4640,17 +4645,21 @@ cp_lu_trychain(yamop *codep, yamop *ocodep, yamop *ostart, int flag, PredEntry *
       break;
     case _trust:
       if (i < ncls-1) goto do_retry;
+      if (!compact_mode) {
+	LogUpdClause *tgl = ClauseCodeToLogUpdClause(ocodep->u.ld.d);
+	tgl->ClRefCount++;
+      }    
       codep = gen_lui_trust(codep, ocodep, profiled, count_reds, ap, ocodep->u.ld.d, TRUE, nblk);
       ocodep = NULL;
       break;
     case _retry_killed:
     case _trust_killed:
-      {
+      if (compact_mode) {
 	LogUpdClause *tgl = ClauseCodeToLogUpdClause(ocodep->u.ld.d);
 
 	tgl->ClRefCount--;
-	ocodep = NEXTOP(ocodep, ld);
       }
+      ocodep = NEXTOP(ocodep, ld);
       break;
     case _trust_logical_pred:
       ocodep = NEXTOP(ocodep, l);
diff --git a/C/tracer.c b/C/tracer.c
index cb7f45cd2..64102bb9b 100644
--- a/C/tracer.c
+++ b/C/tracer.c
@@ -114,6 +114,10 @@ low_level_trace(yap_low_level_port port, PredEntry *pred, CELL *args)
 
   vsc_count++;
 #ifdef COMMENTED
+  if (vsc_count < 5646100000LL)
+    return;
+  if (vsc_count == 5646100441LL)
+    vsc_xstop = TRUE;
   if (vsc_count < 2923351500LL) {
     return;
   }