SAT-Based Area Recovery in Structural Technology Mapping

This paper proposes a fast SAT-based algorithm for recovering area applicable to an already technology mapped circuit. The algorithm considers a sequence of relatively small overlapping regions, called windows, in a mapped network and tries to improve the current mapping of each window using a SAT solver. Delay constraints are considered by interfacing the SAT solver with a timer. Experimental results are given for benchmarks that have been mapped already into 6-LUTs by a high-effort area-only synthesis/mapping flow. The new mapper starting from these results, many of which represented the best known area results at the time, achieved an additional average area reduction of 3-4%, while for some benchmarks the area reduction exceeded 10%. Runtime for any example was only a few seconds.