hacky way to support ECP5 for now

json/jsonparse.cc

@@ -349,7 +349,11 @@ void json_import_net_attrib(Context *ctx, string &modname, NetInfo *net, JsonNod
     else
         log_error("JSON parameter type of \"%s\' of net \'%s\' not supported\n", pId.c_str(ctx),
                   net->name.c_str(ctx));
-
+#ifdef ARCH_ECP5
+    if (param_node->data_dict_keys[param_id]== "NEXTPNR_IS_GLOBAL") {
+        net->is_global = (*dest)[pId].num;
+    }
+#endif
     if (json_debug)
         log_info("    Added parameter \'%s\'=%s to net \'%s\' "
                  "of module \'%s\'\n",

json/jsonwrite.cc

@@ -79,6 +79,11 @@ void write_routing(std::ostream &f, Context *ctx, NetInfo *net, bool first)
     f << stringf("%s\n", first ? "" : ",");
     f << stringf("            \"NEXTPNR_ROUTING\": ");
     f << get_string(routing);
+#ifdef ARCH_ECP5
+    f << stringf(",\n");
+    f << stringf("            \"NEXTPNR_IS_GLOBAL\": ");
+    f << std::to_string(net->is_global ? 1:0);
+#endif
 }
 
 void write_constraints(std::ostream &f, Context *ctx, CellInfo *cell, bool first)