An Open-Source Lightweight Timing Model for RapidWright

Access to detailed timing information for FPGA resources is essential to achieving the highest performance. Yet, for commercial FPGAs, much of this information is not published or available. At the same time, deploying large, fine-grained timing datasets adversely affects the speed of timing-driven place and route algorithms. We propose a nimble timing model for RapidWright that delivers high fidelity timing approximations while enabling faster algorithms through a frugal memory footprint. By leveraging a combination of architectural knowledge, repeating patterns and extensive analysis of Vivado timing reports, we obtain a slightly pessimistic, lumped delay model within 2% average accuracy of Vivado for UltraScale+ devices. We validate the results with over 240 designs and the proposed model shows high fidelity to Vivado with a Spearman's value of 0.99. By open sourcing the proposed model and describing the process, we empower the community to leverage and extend this work for customized domains, other device families, and additional accuracy.