Seeing the forest and the trees

摘要

We show how to optimize Steiner-tree Wirelength (StWL) in global and detail placement without a significant runtime penalty, making the use of Half-Perimeter Wirelength unnecessary. Given that StWL correlates with Routed Wirelength (rWL) much better than HPWL, our new optimization improves the overall Place-and-Route results. We also develop congestion-driven whitespace distribution during global placement. Comparing to the state of the art where whitespace is redistributed after global placement, we demonstrate that cell-shifting techniques often increase via counts.Our placer ROOSTER outperforms best published results for Dragon, Capo, FengShui, mPL-R/WSA and APlace in terms of routed wirelength by 10.7%, 5.6%, 9.3%, 5.5% and 4.2% respectively. Via counts, especially important at 90nm and below, are improved by 15.6% over mPL-R/WSA and 11.9% over APlace.