Abstract

The advent of strong multi-level partitioners has made topdown min-cut placers a favored choice for modern placer implementations. We examine terminal propagation, an important step in min-cut placers, because it is responsible for translating partitioning results into global placement wirelength assumptions. In this work, we identify a previously overlooked problem- ambiguous terminal propagation- and propose a solution based on the concept of feedback from automatic control systems. Implementing our approach in Capo (version 8.7 [5, 10]) and applying it to standard benchmark circuits yields up to 14 % wirelength reductions for the IBM benchmarks and 10 % reductions for PEKO instances. Experiments also show consistent improvements for routed wirelength, yielding up to 9 % wirelength reductions with practical increase in placement runtime. In addition, our method significantly improves routability without building congestion maps, and reduces the number of vias.

Citations

54	Optimal partitioners and end-case placers for standard-cell layout - Caldwell, Kahng, et al. - 2000
47	Optimality and scalability study of existing placement algorithms - Chang, Cong, et al. - 2003
16	On Whitespace and Stability - Adya, Markov, et al. - 2006
5	End-Case Placers for Standard-Cell Layout - Caldwell, Kahng, et al. - 1999