A Robust FPGA Router with Concurrent Intra-CLB Rerouting

Abstract

Routing is the most time-consuming step in the FPGA design flow with increasingly complicated FPGA architectures and design scales. The growing complexity of connections between logic pins inside CLBs of FPGAs challenges the efficiency and quality of FPGA routers. Existing negotiation-based rip-up and reroute schemes will result in a large number of iterations when generating paths inside CLBs. In this work, we propose a robust routing framework for FPGAs with complex connections between logic elements and switch boxes. We propose a concurrent intra-CLB rerouting algorithm that can effectively resolve routing congestion inside a CLB tile. Experimental results on modified ISPD 2016 benchmarks demonstrate that our framework can achieve 100% routability in less wirelength and runtime, while the state-of-theart VTR 8.0 routing algorithm fails at 4 of 12 benchmarks.