Fix issue with interposers and 3D connection blocks

Author: AmirhosseinPoolad

vpr/src/route/rr_graph_generation/interposer_cut.cpp

@@ -110,12 +110,15 @@ std::vector<RREdgeId> mark_interposer_cut_edges_for_removal(const RRGraphView& r
             VTR_LOG("HI\n");
         }
 
-        // TODO: ignoring chanz nodes for now
+        // TODO: ignoring ChanZ nodes for now
         if (rr_graph.node_type(src_node) == e_rr_type::CHANZ || rr_graph.node_type(sink_node) == e_rr_type::CHANZ) {
             continue;
         }
 
-        VTR_ASSERT(rr_graph.node_layer_low(src_node) == rr_graph.node_layer_low(sink_node));
+        // Currently 3D connection block edges cross layers. We don't want to cut these edges.
+        if (rr_graph.node_layer_low(src_node) != rr_graph.node_layer_low(sink_node)) {
+            continue;
+        }
         VTR_ASSERT(rr_graph.node_layer_low(src_node) == rr_graph.node_layer_high(src_node));
         VTR_ASSERT(rr_graph.node_layer_low(sink_node) == rr_graph.node_layer_high(sink_node));
 

vpr/src/route/rr_graph_generation/rr_graph.cpp

@@ -1670,11 +1670,12 @@ static std::function<void(t_chan_width*)> alloc_and_load_rr_graph(RRGraphBuilder
         }
     }
 
-    std::vector<RREdgeId> interposer_edges = mark_interposer_cut_edges_for_removal(rr_graph, grid);
-    rr_graph_builder.remove_edges(interposer_edges);
-
-    update_interposer_crossing_nodes_in_spatial_lookup_and_rr_graph_storage(rr_graph, grid, rr_graph_builder, sg_node_indices);
+    if (!grid.get_horizontal_interposer_cuts().empty() || !grid.get_vertical_interposer_cuts().empty()) {
+        std::vector<RREdgeId> interposer_edges = mark_interposer_cut_edges_for_removal(rr_graph, grid);
+        rr_graph_builder.remove_edges(interposer_edges);
 
+        update_interposer_crossing_nodes_in_spatial_lookup_and_rr_graph_storage(rr_graph, grid, rr_graph_builder, sg_node_indices);
+    }
 
     add_and_connect_non_3d_sg_links(rr_graph_builder, sg_links, sg_node_indices, chan_details_x, chan_details_y, num_seg_types_x, rr_edges_to_create);
     uniquify_edges(rr_edges_to_create);