Parallel standard cell placement algorithms with quality equivalent to simulated annealing

摘要

An algorithm called heuristic spanning creates parallelism by simultaneously investigating different areas of the plausible combinatorial search space. It is used to replace the high-temperature portion of simulated annealing. The low-temperature portion of simulated annealing is sped up by a technique called section annealing, in which placement is geographically divided and the pieces are assigned to separate processors. Each processor generates simulated-annealing-style moves for the cells in its area and communicates the moves to other processors as necessary. Heuristic spanning and section annealing are shown experimentally to converge to the same final cost function as regular simulated annealing. These approaches achieve significant speedup over uniprocessor simulated annealing, giving high-quality VLSI placement of standard cells in a short period of time.