Abstract
Prior works have demonstrated opportunities for achieving more minimized combinational circuits by introducing combinational loops during the synthesis. However, they achieved this by using a branch-and-bound technique to explore possible cyclic dependencies of circuits, which may not scale well for complex designs. Instead of using exploration, this paper proposes a formal algorithm using logic implication to identify cyclifiable structure candidates directly, or to create them aggressively in circuits. Additionally, we also propose a SAT-based algorithm to validate whether the formed loops are combinational or not. The effectiveness and scalability of the identification and validation algorithms are demonstrated in the experimental results performed on a set of IWLS 2005 benchmarks. As compared to the state-of-the-art algorithm, our validation algorithm produces speedups ranging from 2 to 2350 times.