When comparing instance counts to determine is flattening makes a better match,

flatten cells that have no instances in common.
Display a screen message to indicate a re-compare afterr flattening.

base/flatten.c

@@ -1582,7 +1582,8 @@ PrematchLists(char *name1, int file1, char *name2, int file2)
 			}
 		    }
 		    else {
-		       match = 0;
+		       // cell exists in one circuit but not the other, so flatten it.
+		       // match = 0;
 		       break;
 		    }
 		}

tcltk/tclnetgen.c

@@ -2194,6 +2194,7 @@ _netcmp_compare(ClientData clientData,
    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);
    }