Simple FPGA routing graph compression

Abstract: Modern FPGAs continue to increase in capacity which requires more memory to run the CAD flow. The routing resource graph, which is needed by the detailed router, is a memory hungry data structure which describes all of the physical resources and programmable connections within an FPGA. We propose a compression scheme to reduce the memory requirements of the routing resource graph. The scheme is simple to apply and requires only trivial changes to the FPGA detailed routing algorithm. The approach does not require any assumptions about the FPGA routing architecture. Numerical results show excellent compression (as much as 3.6X overall memory reduction) with only a slight increase (~20% on average) on the router runtime as a consequence of the routing graph compression.