Simultaneous Timing Driven Tree Surgery in Routing with Machine Learning-based Acceleration

In global routing, both timing and routability are critical criterions to measure the performance of a design. However, these two objectives naturally conflict with each other during routing. In this paper, a tree surgery technique is presented to adjust routing tree topologies in global routing to fix timing. We formulate the problem as a quadratic program(QP), which adjusts routing topologies of all the nets from a global perspective and takes congestion into consideration to trade off timing and routability objectives. We also apply machine learning-based techniques to accelerate our algorithm, which offers a fast and effective way to solve the problem. Experimental results on ICCAD~2015 benchmarks show that our algorithms can achieve 10.12% timing improvement with no significant degradation in routability and wirelength. With machine learning-based acceleration (MLA), our results can be obtained in almost negligible runtime.