[core] supporting clk spine on the same direction

openfpga/src/annotation/append_clock_rr_graph.cpp

@@ -402,6 +402,61 @@ static std::vector<RRNodeId> find_clock_track2track_node(
     des_nodes.push_back(right_des_node);
   }
 
+  /* U-turn or straight connections */
+  vtr::Point<size_t> top_des_coord = chan_coord;
+  Direction top_direction = direction;
+  t_rr_type top_des_chan_type = chan_type;
+  if (chan_type == CHANX) {
+    if (direction == Direction::INC) {
+      /*
+       *      ^
+       *      |
+       *      +
+       *      |
+       *      ^
+       *      |
+       */
+      right_direction = Direction::DEC;
+    } else {
+      /*
+       *      ^
+       *      |
+       *      +<--
+       */
+      VTR_ASSERT(direction == Direction::DEC);
+      right_direction = Direction::INC;
+      right_des_coord.set_x(right_des_coord.x() - 1);
+      right_des_coord.set_y(right_des_coord.y() + 1);
+    }
+  } else {
+    VTR_ASSERT(chan_type == CHANY);
+    right_des_chan_type = CHANX;
+    if (direction == Direction::INC) {
+      /*
+       *      +-->
+       *      ^
+       *      |
+       */
+      right_des_coord.set_x(right_des_coord.x() + 1);
+    } else {
+      VTR_ASSERT(direction == Direction::DEC);
+      /*
+       *      |
+       *      v
+       *   <--+
+       */
+      right_des_coord.set_y(right_des_coord.y() - 1);
+    }
+  }
+  RRNodeId right_des_node =
+    clk_rr_lookup.find_node(right_des_coord.x(), right_des_coord.y(), clk_tree,
+                            next_clk_lvl, clk_pin, right_direction);
+  if (rr_graph_view.valid_node(right_des_node)) {
+    VTR_ASSERT(right_des_chan_type == rr_graph_view.node_type(right_des_node));
+    des_nodes.push_back(right_des_node);
+  }
+
+
   return des_nodes;
 }