On wirelength estimations for row-based placement
Andrew E. Caldwell, Andrew B. Kahng, Stefanus Mantik, Igor L. Markov, Alex Zelikovsky · 1998
Wirelength estimation in VLSI layout is fundamental to any pre-detailed routing estimate of timing or routability. In this paper, we develop new wirelength estimation techniques appropriate for top-down floor-planning and placement synthesis of row-based VLSI layouts. Our methods include accurate, linear-time approaches, often with sublinear time complexity for dynamic updating of estimates (e.g., for annealing placement). The new techniques offer advantages not only for early on-line wirelength estimation during top-down placement, but also for a posteriori estimation of routed wirelength given a final placement. In developing these new estimators, we have made several theoretical contributions. Notably, we have resolved the long-standing discrepancy between region-based and bounding box-based RSMT estimation techniques; this leads to new estimates that are functions of instance size n and aspect ratio AR.