Parallel FPGA routing based on the operator formulation

We have implemented an FPGA routing algorithm on a shared memory multi-processor using the Galois API, which offers speculative parallelism in software. The router is a parallel implementation of PathFinder, which is the basis for most commercial FPGA routers. We parallelize the maze expansion step for each net, while routing nets sequentially to limit the amount of rollback that would likely occur due to misspeculation. Our implementation relies on non-blocking priority queues, which use software transactional memory (SMT), to identify the best route for each net. Our experimental results demonstrate scalability for large benchmarks and that the amount of available parallelism depends primarily on the circuit size, not the inter-dependence of signals. We achieve an average speedup of approximately 3x compared to the most recently published work on parallel multi-threaded FPGA routing, and up to 6x in comparison to the single-threaded router implemented in the publicly available Versatile Place and Route (VPR) framework.