A global postsynthesis optimization method for combinational circuits

A genetic programming-based circuit synthesis method is proposed that enables to globally optimize the number of gates in circuits that have already been synthesized using common methods such as ABC and SIS. The main contribution is a proposal for a new fitness function that enables to significantly reduce the fitness evaluation time in comparison to the state of the art. The fitness function performs optimized equivalence checking using a SAT solver. It is shown that the equivalence checking time can significantly be reduced when knowledge of the parent circuit and its mutated offspring is taken into account. For a cost of a runtime, results of conventional synthesis conducted using SIS and ABC were improved by 20-40% for the LGSynth93 benchmarks.