Flat Routing Intra-Cluster Node Visualization Incompatible with Z1000 architecture

[SamuelHo10]

When running VPR with the Z1000 architecture and flat routing enabled, I encountered the following issue:

Circuit successfully routed with a channel width factor of 100.
# Synchronize the packed netlist to routing optimization
/home/hosamue3/vtr-verilog-to-routing/vpr/src/base/clustered_netlist.cpp:25 block_pb: Assertion 'valid_block_id(id)' failed.
./vtr.sh: line 12: 2497610 Aborted                 (core dumped) $VTR_ROOT/vpr/vpr $VTR_ROOT/vtr_flow/arch/zeroasic/z1000/z1000.xml $VTR_ROOT/vtr_flow/benchmarks/blif/4/bw.blif --flat_routing on --route_chan_width 100 --device z1000 --clock_modeling route --constant_net_method route --const_gen_inference none --sweep_dangling_primary_ios off --sweep_dangling_nets off --allow_dangling_combinational_nodes on --sweep_constant_primary_outputs off --sweep_dangling_blocks off -j12 --read_rr_graph $VTR_ROOT/vtr_flow/arch/zeroasic/z1000/z1000_rr_graph.xml

It seems that the circuit routes correctly, but afterwards, a block id assertion is triggered. Similarly, when I turned on graphics to visualize intra-cluster routing, I ran into the error:

Circuit successfully routed with a channel width factor of 100.
/home/hosamue3/vtr-verilog-to-routing/vpr/src/util/vpr_utils.cpp:1771 get_rr_node_cluster_blk_id_pb_graph_pin: Assertion 'blk_id != ClusterBlockId::INVALID()' failed.
./gui.sh: line 14: 2498796 Aborted                 (core dumped) $VTR_ROOT/vpr/vpr $VTR_ROOT/vtr_flow/arch/zeroasic/z1000/z1000.xml $VTR_ROOT/vtr_flow/benchmarks/blif/4/bw.blif --disp on --analysis --flat_routing on --route_chan_width 100 --device z1000 --clock_modeling route --constant_net_method route --const_gen_inference none --sweep_dangling_primary_ios off --sweep_dangling_nets off --allow_dangling_combinational_nodes on --sweep_constant_primary_outputs off --sweep_dangling_blocks off -j12 --read_rr_graph $VTR_ROOT/vtr_flow/arch/zeroasic/z1000/z1000_rr_graph.xml

Alex suggested that this issue might be caused by the architecture’s perimeter of empty tiles.

[vaughnbetz]

@samuel: one thing to try based on @AlexandreSinger 's idea: let's test if this is due to reading in an rr-graph.

• Take one design on one architecture that works (e.g. VTR, LU8) and use --write_rr_graph to write out an rr-graph in the first run, with flat routing enabled.
• Do a second run with --read_rr_graph (all other options the same). If it works, reading an rr-graph with flat routing is fine.

@amin1377 : the assert is in the post-routing synchronization of the intra-cluster routes, which I think you updated and landed (and which contains code by Xifan and Fahri).

[vaughnbetz]

@SamuelHo10 : one other test:
Try removing --clock_modeling route --constant_net_method route . It simplifies the problem a bit and would help us localize things a bit.

[SamuelHo10]

Reading an rr_graph with flat routing seems to work. However, even after removing the --clock_modeling route --constant_net_method route flags, the valid_block_id assertion gets triggered with the z1000 arch.

[SamuelHo10]

I printed out grid_blocks right before the assertion was triggered, and it seems that the clusterblock id at index 0 which it is trying to access has id == -1.