Merge branch 'master' into netgen-1.5

is my typographic preference.

.gitignore

@@ -7,6 +7,7 @@ config.log
 scripts/config.log
 config.status
 scripts/config.status
+python/lvs_manager.py
 *.o
 *.so
 *~

VERSION

@@ -1 +1 @@
-1.5.211
+1.5.217

base/flatten.c

@@ -372,22 +372,16 @@ int flattenInstancesOf(char *name, int fnum, char *instance)
 
          /* update node numbers in child to unique numbers */
          oldmax = 0;
-         for (tmp = ChildStart; tmp != NULL; tmp = tmp->next) 
+         for (tmp = ChildStart; tmp != NULL; tmp = tmp->next) {
 	    if (tmp->node > oldmax) oldmax = tmp->node;
-         if (nextnode <= oldmax) nextnode = oldmax + 1;
-
-         for (tmp = ChildStart; tmp != NULL; tmp = tmp->next) 
-	    if (tmp->node <= oldmax && tmp->node > 0) {
-	       if (Debug) Printf("Update node %d --> %d\n", tmp->node, nextnode);
-	       UpdateNodeNumbers(ChildStart, tmp->node, nextnode);
-	       nextnode++;
-	    }
+	    if (tmp->node > 0) tmp->node += (nextnode - 1);
+	 }
+	 nextnode += oldmax;
 
          /* copy nodenumbers of ports from parent */
          ob2 = ParentParams;
-         for (tmp = ChildStart; tmp != NULL; tmp = tmp->next)  {
-	    if (IsPort(tmp)) {
-	       if (tmp->node > 0) {
+         for (tmp = ChildStart; tmp && IsPort(tmp); tmp = tmp->next)  {
+	     if (tmp->node > 0) {
 	          if (ob2->node == -1) {
 
 	             // Before commiting to attaching to a unconnected node, see
@@ -413,17 +407,16 @@ int flattenInstancesOf(char *name, int fnum, char *instance)
 	             Printf("Update node %d --> %d\n", tmp->node, ob2->node);
 	          }
 	          UpdateNodeNumbers(ChildStart, tmp->node, ob2->node);
-	       }
+	     }
 
-	       /* in pathological cases, the lengths of the port lists may
-                * change.  This is an error, but that is no reason to allow
-                * the code to core dump.  We avoid this by placing a 
-                * superfluous check on ob2->type
-                */
-	       if (ob2 != NULL) ob2 = ob2->next;
+	     /* in pathological cases, the lengths of the port lists may
+              * change.  This is an error, but that is no reason to allow
+              * the code to core dump.  We avoid this by placing a 
+              * superfluous check on ob2->type
+              */
+	     if (ob2 != NULL) ob2 = ob2->next;
 
-	       if (ob2 == NULL) break;
-	    }
+	     if (ob2 == NULL) break;
 	 }
 
          /* Using name == NULL to indicate that a .ext file is being 	*/
@@ -1421,6 +1414,22 @@ typedef struct ecomplist {
     ECompListPtr next;
 } ECompList;
 
+/*----------------------------------------------------------------------*/
+/* Determine if a cell contains at least one device or subcircuit	*/
+/*----------------------------------------------------------------------*/
+
+int
+HasContents(struct nlist *tc)
+{
+    struct objlist *ob;
+
+    for (ob = tc->cell; ob; ob = ob->next)
+	if (ob->type == FIRSTPIN)
+	    return TRUE;
+
+    return FALSE;
+}
+
 /*------------------------------------------------------*/
 /* Survey the contents of a cell and sort into a hash	*/
 /*------------------------------------------------------*/
@@ -1518,6 +1527,7 @@ PrematchLists(char *name1, int file1, char *name2, int file2)
     struct hashdict compdict;
     ECompare *ecomp, *ncomp;
     ECompList *list0X, *listX0;
+    int hascontents1, hascontents2;
     int match, modified = 0;
 
     if (file1 == -1)
@@ -1533,6 +1543,7 @@ PrematchLists(char *name1, int file1, char *name2, int file2)
     if (tc1 == NULL || tc2 == NULL) return 0;
 
     InitializeHashTable(&compdict, OBJHASHSIZE);
+    listX0 = list0X = NULL;
 
     // Gather information about instances of cell "name1"
     SurveyCell(tc1, &compdict, file1, file2, 0);
@@ -1545,7 +1556,6 @@ PrematchLists(char *name1, int file1, char *name2, int file2)
     // in the hierarchy of each instance contain devices
     // or subcircuits that have more in the compared circuit.
 
-    listX0 = list0X = NULL;
     ecomp = (ECompare *)HashFirst(&compdict);
     while (ecomp != NULL) {
 
@@ -1590,15 +1600,15 @@ PrematchLists(char *name1, int file1, char *name2, int file2)
 	    }
 	    if (match) {
 		if (ecomp->cell1 && (ecomp->num1 > 0)) {
-		    Fprintf(stdout, "Flattening instances of %s in cell %s"
+		    Fprintf(stdout, "Flattening instances of %s in cell %s (%d)"
 				" makes a better match\n", ecomp->cell1->name,
-				name1);
+				name1, file1);
 		    flattenInstancesOf(name1, file1, ecomp->cell1->name); 
 		}
 		if (ecomp->cell2 && (ecomp->num2 > 0)) {
-		    Fprintf(stdout, "Flattening instances of %s in cell %s"
+		    Fprintf(stdout, "Flattening instances of %s in cell %s (%d)"
 				" makes a better match\n", ecomp->cell2->name,
-				name2);
+				name2, file2);
 		    flattenInstancesOf(name2, file2, ecomp->cell2->name); 
 		}
 		modified++;
@@ -1650,7 +1660,7 @@ PrematchLists(char *name1, int file1, char *name2, int file2)
 	}
 
 	/* Case 2:  Cell2 class is a subcircuit, and flattening	*/
-	/* (it without regard to cell1) improves the matching.	*/
+	/* it (without regard to cell1) improves the matching.	*/
 
 	else if ((ecomp->num1 != ecomp->num2) && (ecomp->cell2 != NULL) &&
 			(ecomp->num2 != 0) && (ecomp->cell2->class == CLASS_SUBCKT)) {
@@ -1679,9 +1689,9 @@ PrematchLists(char *name1, int file1, char *name2, int file2)
 	    }
 	    if (match) {
 		if (ecomp->cell2) {
-		    Fprintf(stdout, "Flattening instances of %s in cell %s"
+		    Fprintf(stdout, "Flattening instances of %s in cell %s (%d)"
 				" makes a better match\n", ecomp->cell2->name,
-				name2);
+				name2, file2);
 		    flattenInstancesOf(name2, file2, ecomp->cell2->name); 
 		}
 		modified++;
@@ -1708,7 +1718,7 @@ PrematchLists(char *name1, int file1, char *name2, int file2)
 	}
 	
 	/* Case 3:  Cell1 class is a subcircuit, and flattening	*/
-	/* (it without regard to cell1) improves the matching.	*/
+	/* it (without regard to cell1) improves the matching.	*/
 
 	else if ((ecomp->num1 != ecomp->num2) && (ecomp->cell1 != NULL) &&
 			(ecomp->num1 != 0) && (ecomp->cell1->class == CLASS_SUBCKT)) {
@@ -1737,9 +1747,9 @@ PrematchLists(char *name1, int file1, char *name2, int file2)
 	    }
 	    if (match) {
 		if (ecomp->cell1) {
-		    Fprintf(stdout, "Flattening instances of %s in cell %s"
+		    Fprintf(stdout, "Flattening instances of %s in cell %s (%d)"
 				" makes a better match\n", ecomp->cell1->name,
-				name1);
+				name1, file1);
 		    flattenInstancesOf(name1, file1, ecomp->cell1->name); 
 		}
 		modified++;
@@ -1820,9 +1830,9 @@ PrematchLists(char *name1, int file1, char *name2, int file2)
 				    }
 				    if (found) {
 					Fprintf(stdout, "Removing zero-valued device "
-						"%s from cell %s makes a better match\n",
-						tsub1->name,
-						tc1->name);
+						"%s from cell %s (%d) makes a better "
+						"match\n",
+						tsub1->name, tc1->name, tc1->file);
 
 					/* A current source is an open, while a	    */
 					/* resistor or voltage source is a short.   */
@@ -1931,9 +1941,9 @@ PrematchLists(char *name1, int file1, char *name2, int file2)
 				    }
 				    if (found) {
 					Fprintf(stdout, "Removing zero-valued device "
-						"%s from cell %s makes a better match\n",
-						tsub2->name,
-						tc2->name);
+						"%s from cell %s (%d) makes a better "
+						"match\n",
+						tsub2->name, tc2->name, tc2->file);
 
 					/* merge node of endpoints */
 					if (ecomp->cell2->class != CLASS_ISOURCE) {
@@ -2024,8 +2034,8 @@ PrematchLists(char *name1, int file1, char *name2, int file2)
 			    if (dstr) *dstr = '[';
 			    if ((ncomp == ecomp0X) && (ecomp0X->num2 <= ecompX0->num1)) {
 				Fprintf(stdout, "Flattening instances of %s in cell %s"
-					" makes a better match\n", ecompX0->cell1->name,
-					name1);
+					"(%d) makes a better match\n",
+					ecompX0->cell1->name, name1, file1);
 				flattenInstancesOf(name1, file1, ecompX0->cell1->name); 
 			        ecompX0->num1 = 0;
 			        ecomp0X->num1 += ecompX0->num1;
@@ -2050,8 +2060,8 @@ PrematchLists(char *name1, int file1, char *name2, int file2)
 			    if (dstr) *dstr = '[';
 			    if ((ncomp == ecompX0) && (ecompX0->num1 <= ecomp0X->num2)) {
 				Fprintf(stdout, "Flattening instances of %s in cell %s"
-					" makes a better match\n", ecomp0X->cell2->name,
-					name2);
+					" (%d) makes a better match\n",
+					ecomp0X->cell2->name, name2, file2);
 				flattenInstancesOf(name2, file2, ecomp0X->cell2->name); 
 			        ecomp0X->num2 = 0;
 			        ecompX0->num2 += ecomp0X->num2;
@@ -2065,6 +2075,7 @@ PrematchLists(char *name1, int file1, char *name2, int file2)
 	}
     }
 
+done:
     // Free the hash table and its contents.
 
     ecomp = (ECompare *)HashFirst(&compdict);

base/flatten.h

@@ -3,5 +3,6 @@
 
 extern int UniquePins(char *name, int filenum);
 extern void flattenCell(char *name, int file);
+extern int HasContents(struct nlist *);
 
 #endif /* _FLATTEN_H */

base/netcmp.c

@@ -3667,12 +3667,19 @@ int CreateCompareQueue(char *name1, int file1, char *name2, int file2)
          Fprintf(stdout, "Descend level %d circuit 2\n", level);
       DescendCompareQueue(tc2, tc1, level, 0, 1);
 
+      /* NOTE:  Preemptive flattening is inefficient and can cause
+       * unnecessary flattening of cells that will never be compared.
+       * let the prematch stage take care of this.
+       */
+      /*--------------------------------------
       if (Debug == TRUE)
          Fprintf(stdout, "Flatten level %d circuit 1\n", level);
       FlattenUnmatched(tc1, name1, level, 0);
       if (Debug == TRUE)
          Fprintf(stdout, "Flatten level %d circuit 2\n", level);
       FlattenUnmatched(tc2, name2, level, 0);
+      ---------------------------------------*/
+
       level--;
    }
 
@@ -3751,8 +3758,23 @@ void RemoveCompareQueue()
    CompareQueue = NULL;
 }
 
+/*----------------------------------------------------------------------*/
+/* Output a summary of the contents of the two circuits being compared	*/
+/*----------------------------------------------------------------------*/
+
+void DescribeContents(char *name1, int file1, char *name2, int file2)
+{
+    Fprintf(stdout, "\n");  // blank line before new circuit diagnostics in log file
+    /* print preliminary statistics */
+    Printf("\nContents of circuit 1:  ");
+    DescribeInstance(name1, file1);
+    Printf("Contents of circuit 2:  ");
+    DescribeInstance(name2, file2);
+    Printf("\n");
+}
+
 /*----------------------------------*/
-/* create an initial data structure */
+/* Create an initial data structure */
 /*----------------------------------*/
 
 void CreateTwoLists(char *name1, int file1, char *name2, int file2, int dolist)
@@ -3764,14 +3786,6 @@ void CreateTwoLists(char *name1, int file1, char *name2, int file2, int dolist)
 
     ResetState();
 
-    Fprintf(stdout, "\n");  // blank line before new circuit diagnostics in log file
-    /* print preliminary statistics */
-    Printf("\nContents of circuit 1:  ");
-    DescribeInstance(name1, file1);
-    Printf("Contents of circuit 2:  ");
-    DescribeInstance(name2, file2);
-    Printf("\n");
-
     if (file1 == -1)
         tc1 = LookupCell(name1);
     else
@@ -7931,6 +7945,7 @@ int Compare(char *cell1, char *cell2)
 {
   int automorphisms;
 
+  DescribeContents(cell1, -1, cell2, -1);
   CreateTwoLists(cell1, -1, cell2, -1, 0);
   Permute();
   while (!Iterate()); 
@@ -7991,6 +8006,7 @@ void NETCOMP(void)
     case 'c':
       promptstring("Enter cell 1: ",name);
       promptstring("Enter cell 2: ",name2);
+      DescribeContents(name, -1, name2, -1);
       CreateTwoLists(name, -1, name2, -1, 0);
 #ifdef DEBUG_ALLOC
       PrintCoreStats();

base/netcmp.h

@@ -26,6 +26,7 @@ extern void PrintCoreStats(void);
 extern void ResetState(void);
 extern void CreateTwoLists(char *name1, int file1, char *name2, int file2,
 		int dolist);
+extern void DescribeContents(char *name1, int file1, char *name2, int file2);
 extern int Iterate(void);
 extern int VerifyMatching(void);
 extern void PrintAutomorphisms(void);
@@ -46,6 +47,7 @@ extern int  CreateCompareQueue(char *, int, char *, int);
 extern int  GetCompareQueueTop(char **, int *, char **, int *);
 extern int  PeekCompareQueueTop(char **, int *, char **, int *);
 extern void RemoveCompareQueue();
+extern int FlattenUnmatched(struct nlist *, char *, int, int);
 
 extern void PrintIllegalClasses();
 extern void PrintIllegalNodeClasses();

base/netgen.c

@@ -3441,7 +3441,8 @@ int CombineParallel(char *model, int file)
    }
    HashKill(&devdict);
    if (dcnt > 0) {
-      Fprintf(stdout, "Class %s(%d):  Merged %d parallel devices.\n", model, file, dcnt);
+      Fprintf(stdout, "Class %s (%d):  Merged %d parallel devices.\n",
+		model, file, dcnt);
    }
    FREE(nodecount);
    return dcnt;
@@ -3739,7 +3740,8 @@ int CombineSeries(char *model, int file)
    }
    FREE(instlist);
    if (scnt > 0) {
-      Fprintf(stdout, "Class %s(%d):  Merged %d series devices.\n", model, file, scnt);
+      Fprintf(stdout, "Class %s (%d):  Merged %d series devices.\n",
+		model, file, scnt);
    }
    return scnt;
 }

base/query.c

@@ -805,11 +805,14 @@ void DescribeInstance(char *name, int file)
       /* All black-box modules and placeholders by definition have all	*/
       /* disconnected pins, so don't report those.			*/
 
-      if (!(tp->flags & CELL_PLACEHOLDER) && (tp->class != CLASS_MODULE))
-      {
-	//if (disconnectednodes == 0) Fprintf(stderr, "\n");
+      if ((!(tp->flags & CELL_PLACEHOLDER)) && (tp->class != CLASS_MODULE)) {
+	// if (disconnectednodes == 0) Fprintf(stderr, "\n");
         disconnectednodes++;
-        Fprintf(stderr, "Cell %s(%d) disconnected node: %s\n", tp->name, tp->file, ob->name);
+	/* Don't report on ports marked "port_match_error", which is just confusing. */
+	if (strcmp(ob->name, "port_match_error")) {
+           Fprintf(stderr, "Cell %s (%d) disconnected node: %s\n",
+		    tp->name, tp->file, ob->name);
+	}
       }
     }
   }

base/spice.c

@@ -940,7 +940,7 @@ skip_ends:
 	 goto baddevice;
       }
 
-      snprintf(instname, 255, "%s%s", model, inst);
+      snprintf(instname, 255, "%s:%s", model, inst);
       Cell(instname, model, collector, base, emitter);
       pobj = LinkProperties(model, kvlist);
       ReduceExpressions(pobj, NULL, CurrentCell, TRUE);
@@ -1013,7 +1013,7 @@ skip_ends:
 	 goto baddevice;
       }
 
-      snprintf(instname, 255, "%s%s", model, inst);
+      snprintf(instname, 255, "%s:%s", model, inst);
       Cell(instname, model, drain, gate, source, bulk);
       pobj = LinkProperties(model, kvlist);
       ReduceExpressions(pobj, NULL, CurrentCell, TRUE);
@@ -1104,7 +1104,7 @@ skip_ends:
 	   usemodel = 1;
 	}
 
-	snprintf(instname, 255, "%s%s", model, inst);
+	snprintf(instname, 255, "%s:%s", model, inst);
 	if (usemodel)
            Cell(instname, model, ctop, cbot);
 	else
@@ -1197,7 +1197,7 @@ skip_ends:
 	else
 	   strcpy(model, "r");		/* Use default resistor model */
 
-	snprintf(instname, 255, "%s%s", model, inst);
+	snprintf(instname, 255, "%s:%s", model, inst);
 	if (usemodel)
 	   Cell(instname, model, rtop, rbot);
 	else
@@ -1255,7 +1255,7 @@ skip_ends:
 	 Fprintf(stderr, "Device \"%s\" has wrong number of ports for a diode.\n");
 	 goto baddevice;
       }
-      snprintf(instname, 255, "%s%s", model, inst);
+      snprintf(instname, 255, "%s:%s", model, inst);
       Cell(instname, model, anode, cathode);
       pobj = LinkProperties(model, kvlist);
       ReduceExpressions(pobj, NULL, CurrentCell, TRUE);
@@ -1334,7 +1334,7 @@ skip_ends:
 	else
 	   strcpy(model, "t");		/* Use default xline model */
 
-	snprintf(instname, 255, "%s%s", model, inst);
+	snprintf(instname, 255, "%s:%s", model, inst);
 
 	if (usemodel)
 	   Cell(instname, model, node1, node2, node3, node4);
@@ -1417,7 +1417,7 @@ skip_ends:
       else
 	 strcpy(model, "l");		/* Use default inductor model */
 
-      snprintf(instname, 255, "%s%s", model, inst);
+      snprintf(instname, 255, "%s:%s", model, inst);
       if (usemodel)
 	 Cell(instname, model, end_a, end_b);
       else
@@ -1729,7 +1729,7 @@ skip_ends:
       /* names.								  */
 
       if (strncmp(instancename, scan->name, strlen(scan->name))) {
-         snprintf(subcktname, 99, "%s%s", scan->name, instancename);
+         snprintf(subcktname, 99, "%s:%s", scan->name, instancename);
          strcpy(instancename, subcktname);
       }
       else {

base/verilog.c

@@ -1778,54 +1778,6 @@ nextinst:
 	    scan->width = width;
 
 	    result = GetBus(scan->net, &wb);
-	    if (result == -1) {
-		/* CHECK:  THIS CODE SHOULD BE DELETED, IT IS NOT THE ISSUE */
-		/* Not bus notation, but check if signal was defined as a bus */
-		wb.start = wb.end = -1;
-		minnet = maxnet = -1;
-
-		/* Pins should be in index order start->end.  Other nodes */
-		/* should be in order start->end by node number.	  */
-
-		for (bobj = CurrentCell->cell; bobj; bobj = bobj->next) {
-		    if (bobj->type == PORT) {
-			if ((bptr = strvchr(bobj->name, '[')) != NULL) {
-			    *bptr = '\0';
-			    if (!strcmp(bobj->name, scan->net)) {
-				*bptr = '[';
-				if (wb.start == -1)
-				    sscanf(bptr + 1, "%d", &wb.start);
-				else
-				    sscanf(bptr + 1, "%d", &wb.end);
-			    }
-			}
-		    }
-		    else if (bobj->type == NODE) {
-			if ((bptr = strvchr(bobj->name, '[')) != NULL) {
-			    *bptr = '\0';
-			    if (!strcmp(bobj->name, scan->net)) {
-				if (sscanf(bptr + 1, "%d", &testidx) == 1) {
-				    if (minnet == -1) {
-					minnet = maxnet = bobj->node;
-					wb.start = wb.end = testidx;
-				    }
-				    else if (bobj->node < minnet) {
-					minnet = bobj->node;
-					wb.start = testidx;
-				    }
-				    else if (bobj->node > maxnet) {
-					maxnet = bobj->node;
-					wb.end = testidx;
-				    }
-				}
-			    }
-			    *bptr = '[';
-			}
-		    }
-		}
-		if (wb.start != -1) result = 0;
-	    }
-
 	    if (result == 0) {
 	       int match = 0;
 	       int wblen, arraylen;
@@ -1935,7 +1887,25 @@ nextinst:
 	       }
 	    }
 	    else if (portstart != portend) {
-	       Fprintf(stderr, "Error:  Single net %s is connected to bus port %s\n",
+	       /* If the name starts with "_noconnect_", then it was an
+		* auto-generated name that incorrectly assumed a single-bit
+		* wide signal because it did not have a module prototype.
+		* Rewrite the noconnect name as an array.  This just means
+		* that the verilog had an empty list "()" and the initial
+		* assumption was wrong.  If not all instances agree on the
+		* size, then this will eventually generate an error.
+		*/
+	       if (!strncmp(scan->net, "_noconnect_", 11) &&
+			(strchr(scan->net, '\[') == NULL) && (width > 1)) {
+		  char *savenet = scan->net;
+		  char *newnet = MALLOC(strlen(scan->net) + 12);
+		  sprintf(newnet, "%s[%d:0]", scan->net, scan->width - 1);
+		  FREE(savenet);
+		  scan->net = newnet;
+		  continue;	/* Re-process this entry */
+	       }
+	       else
+	          Fprintf(stderr, "Error:  Single net %s is connected to bus port %s\n",
 			scan->net, scan->name);
 	    }
 	 }
@@ -2117,7 +2087,7 @@ nextinst:
 					sobj = sobj->next) {
 			      if (sobj->type == FIRSTPIN) {
 				 if (match(sobj->model.class, obptr->model.class)) {
-				    while (sobj->next->type > FIRSTPIN)
+				    while (sobj->next && (sobj->next->type > FIRSTPIN))
 				       sobj = sobj->next;
 				    /* Stop when reaching the current instance */
 				    if (sobj->type == obptr->type + 1) break;

tcltk/tclnetgen.c

@@ -2095,8 +2095,9 @@ _netcmp_compare(ClientData clientData,
    int dohierarchy = FALSE;
    int assignonly = FALSE;
    int argstart = 1, qresult, llen, result;
+   int hascontents1, hascontents2;
    struct Correspond *nextcomp;
-   struct nlist *tp;
+   struct nlist *tp1 = NULL, *tp2 = NULL;
    Tcl_Obj *flist = NULL;
 
    if (objc > 1) {
@@ -2139,24 +2140,24 @@ _netcmp_compare(ClientData clientData,
       }
       else if ((objc - argstart) == 2) {
 
-	 result = CommonParseCell(interp, objv[argstart], &tp, &fnum1);
+	 result = CommonParseCell(interp, objv[argstart], &tp1, &fnum1);
          if (result != TCL_OK) return TCL_ERROR;
 	 else if (fnum1 == -1) {
 	    Tcl_SetResult(interp, "Cannot use wildcard with compare command.\n",
 			NULL);
 	    return TCL_ERROR;
 	 }
-         name1 = tp->name;
+         name1 = tp1->name;
 	 argstart++;
 
-	 result = CommonParseCell(interp, objv[argstart], &tp, &fnum2);
+	 result = CommonParseCell(interp, objv[argstart], &tp2, &fnum2);
          if (result != TCL_OK) return TCL_ERROR;
 	 else if (fnum2 == -1) {
 	    Tcl_SetResult(interp, "Cannot use wildcard with compare command.\n",
 			NULL);
 	    return TCL_ERROR;
 	 }
-         name2 = tp->name;
+         name2 = tp2->name;
 
          if (dohierarchy) {
 	    RemoveCompareQueue();
@@ -2195,12 +2196,34 @@ _netcmp_compare(ClientData clientData,
       ConvertGlobals(name2, fnum2);
    }
 
-   CreateTwoLists(name1, fnum1, name2, fnum2, dolist);
-   while (PrematchLists(name1, fnum1, name2, fnum2) > 0) {
-      Fprintf(stdout, "Making another compare attempt.\n");
-      Printf("Flattened mismatched instances and attempting compare again.\n");
-      CreateTwoLists(name1, fnum1, name2, fnum2, dolist);
+   tp1 = LookupCellFile(name1, fnum1);
+   tp2 = LookupCellFile(name2, fnum2);
+
+   hascontents1 = HasContents(tp1);
+   hascontents2 = HasContents(tp2);
+
+   if (hascontents1 && !hascontents2 && (tp2->flags & CELL_PLACEHOLDER)) {
+       Fprintf(stdout, "Circuit 2 cell %s is a black box; will not flatten "
+                        "Circuit 1\n", name2);
    }
+   else if (hascontents2 && !hascontents1 && (tp1->flags & CELL_PLACEHOLDER)) {
+       Fprintf(stdout, "Circuit 1 cell %s is a black box; will not flatten "
+                        "Circuit 2\n", name1);
+   }
+   else if (hascontents1 || hascontents2) {
+       FlattenUnmatched(tp1, name1, 1, 0);
+       FlattenUnmatched(tp2, name2, 1, 0);
+       DescribeContents(name1, fnum1, name2, fnum2);
+
+       while (PrematchLists(name1, fnum1, name2, fnum2) > 0) {
+          Fprintf(stdout, "Making another compare attempt.\n");
+          Printf("Flattened mismatched instances and attempting compare again.\n");
+          FlattenUnmatched(tp1, name1, 1, 0);
+          FlattenUnmatched(tp2, name2, 1, 0);
+          DescribeContents(name1, fnum1, name2, fnum2);
+       }
+   }
+   CreateTwoLists(name1, fnum1, name2, fnum2, dolist);
 
    // Return the names of the two cells being compared, if doing "compare
    // hierarchical".  If "-list" was specified, then append the output
@@ -3032,11 +3055,11 @@ _netcmp_equate(ClientData clientData,
 			(tp2->flags & CELL_PLACEHOLDER)) {
 		if (tp1->flags & CELL_PLACEHOLDER) {
 		    Fprintf(stdout, "Warning: Equate pins:  cell %s "
-			"has no definition, treated as a black box.\n", name1);
+			"is a placeholder, treated as a black box.\n", name1);
 		}
 		if (tp2->flags & CELL_PLACEHOLDER) {
 		    Fprintf(stdout, "Warning: Equate pins:  cell %s "
-			"has no definition, treated as a black box.\n", name2);
+			"is a placeholder, treated as a black box.\n", name2);
 		}
 		// If a cell in either circuit is marked as a black box, then
 		// the cells in both circuits should be marked as a black box.