grt: Issue an error if design does not have any routable net (with at…

… least 2 terms).

Signed-off-by: Christian Costa <[email protected]>

src/grt/src/GlobalRouter.cpp

@@ -246,6 +246,19 @@ void GlobalRouter::globalRoute(bool save_guides,
                                bool start_incremental,
                                bool end_incremental)
 {
+  bool has_routable_nets = false;
+  for (auto net : db_->getChip()->getBlock()->getNets()) {
+    if (net->getITerms().size() + net->getBTerms().size() > 1) {
+      has_routable_nets = true;
+      break;
+    }
+  }
+  if (!has_routable_nets) {
+    logger_->error(GRT,
+                   5,
+                   "Design does not have any routable net "
+                   "(with at least 2 terms)");
+  }
   if (start_incremental && end_incremental) {
     logger_->error(GRT,
                    251,