Local unidirectional bias for smooth cutsize-delay tradeoff in performance-driven bipartitioning

Traditional multilevel partitioning approaches have shown good performance with respect to cutsize, but offer no guarantees with respect to system performance. Timing-driven partitioning methods based on iterated net reweighting, partitioning and timing analysis have been proposed [2], as well as methods that apply degrees of freedom such as retiming [7][5]. In this work, we identify and validate a simple approach to timing-driven partitioning, based on the concept of "V-shaped nodes". We observe that the presence of V-shaped nodes can badly impact circuit performance, as measured by maximum hopcount across the cutline or similar path delay criteria. We extend traditional KLFM approaches to directly eliminate or minimize "distance-k V-shaped nodes" in the bipartitioning solution, achieving a smooth trade-off between cutsize and path delay. Experiments show that in comparison to MLPart [4], our method can reduce the maximum hopcount by 39% while only slightly increasing cutsize and runtime. No previous method improves path delay in such a transparent manner.