An effective routability-driven packing algorithm for large-scale heterogeneous FPGAs

Abstract

With the growing complexity and scale of FPGA architectures, challenges posed by heterogeneity and routability have become more pronounced in FPGA packing. Conventional FPGA packing algorithms are seldom considered routability and may lead to unroutable results. This paper addresses these challenges by proposing an effective routability-driven packing algorithm tailored for large-scale heterogeneous FPGAs. The proposed algorithm consists of four major parts: (1) a LUT-FF pairing method is presented to pack LUTs and FFs into LUT-FF pairs. (2) A novel BLE packing method is presented to deal with the complex clock constraints, meanwhile forming more HCLB-friendly BLEs. (3) A congestion-aware HCLB packing technique is proposed to produce placement-friendly netlists without degrading routability. (4) An effective and accurate routing congestion estimation method is proposed to guide the packing process. Based on the ISPD 2017 clock-aware FPGA placement contest benchmarks, experimental results show that our algorithm outperforms three state-of-the-art FPGA placers by 9.8%, 8.2%, and 3.4% on routed wirelength, respectively.