POLAR 2.0: An effective routability-driven placer

A wirelength-driven placer without considering routability would lead to unroutable results. To mitigate routing congestion, there are two basic approaches: (1) minimizing the routing demand; (2) distributing the routing demand properly. In this paper, we propose a new placer POLAR 2.0 emphasizing both approaches. To minimize the routing demand, POLAR 2.0 attaches very high importance to maintaining a good wirelength-driven placement in the global placement stage. To distribute the routing demand, cells in congested regions are spread out by a novel routability-driven rough legalization in a global manner and by a history based cell inflation technique in a local manner. The experimental results based on ICCAD 2012 contest benchmark suite show that POLAR 2.0 outperforms all published academic routability-driven placers both in runtime and quality.