A fast maze-free routing congestion estimator with hybrid unilateral monotonic routing

Considering routability issue in the early stages of VLSI design flow can avoid generating an unroutable design. Several recent routablity-driven placers [8-11] adopt a built-in global router to estimate routing congestion. While the routability of the placement solution improves, the performance of these placers degrades. Many of these built-in global router and state-of-the-art academic global routers use maze routing to seek a detoured path. Although very effective, maze routing is relatively slower than other routing algorithms, such as pattern routing and monotonic routing algorithms. This work presents two efficient routing algorithms, called unilateral monotonic routing and hybrid unilateral monotonic routing, to replace maze routing and to realize a highly fast maze-free global router that is suited to act as a built-in routing congestion estimator for placers. Experimental results indicate that RCE achieves similar routing quality when compared with [20], as well as an over 20-fold runtime speedup in large benchmarks.