Merge pull request #8840 from The-OpenROAD-Project-staging/grt_fix_incremental

grt: initialize FastRoute during incremental

Author: maliberty

src/grt/src/GlobalRouter.cpp

@@ -5204,6 +5204,12 @@ std::vector<Net*> GlobalRouter::updateDirtyRoutes(bool save_guides)
   callback_handler_->triggerOnPinAccessUpdateRequired();
   std::vector<Net*> dirty_nets;
 
+  if (!initialized_) {
+    int min_layer, max_layer;
+    getMinMaxLayer(min_layer, max_layer);
+    initFastRoute(min_layer, max_layer);
+  }
+
   if (!dirty_nets_.empty()) {
     fastroute_->setVerbose(false);
     fastroute_->clearNetsToRoute();