FPGA area reduction by multi-output function based sequential resynthesis

We propose a new resynthesis algorithm for FPGA area reduction. In contrast to existing resynthesis techniques, which consider only single-output Boolean functions and the combinational portion of a circuit, we consider multi-output functions and retiming, and develop effective algorithms that incorporate recent improvements to SAT-based Boolean matching. Our experimental results show that with the optimal logic depth, the resynthesis considering multi-output functions reduces area by up to 0.4% compared to the one considering single-output functions, and the sequential resynthesis reduces area by up to 10% compared to combinational resynthesis when both consider multi-output functions. Furthermore, our proposed resynthesis algorithm reduces area by up to 16% compared to the best existing academic technology mapper, Berrylikei ABC.