AlphaSyn: Logic Synthesis Optimization with Efficient Monte Carlo Tree Search

Zehua Pei, Fangzhou Liu, Zhuolun He, Guojin Chen, Haisheng Zheng, Keren Zhu, Bei Yu

Abstract: Recent years have seen rising research in logic synthesis recipe generation to improve the Quality-of-Result (QoR). However, existing approaches typically have low efficiency and are stuck at local optima. In this work, we propose a logic synthesis optimization framework, AlphaSyn, that incorporates a domain-specific Monte Carlo tree search (MCTS) algorithm. AlphaSyn enables exploration across the entire search space while optimizing sampling points utilization. We further develop a synthesis-specific upper confidence bound for trees (SynUCT) algorithm for the selection phase and a well-designed learning strategy to enhance the stability of the MCTS algorithm. The AlphaSyn algorithm is fully parallelized for efficiency with asynchronous MCTS exploration and significance-base resource allocation. For standard-cell technology mapping on the ASAP 7nm library among other tasks, experimental results show that AlphaSyn outperforms SOTA FlowTune with an average 8.74% area reduction and $\boldsymbol{1.24}\times$ runtime speedup.