An efficient routing tree construction algorithm with buffer insertion, wire sizing and obstacle considerations

We propose a fast algorithm to construct a performance driven routing tree with simultaneous buffer insertion and wire sizing in the presence of wire and buffer obstacles. Several algorithms (J. Lillis et al., 1996; M. Hrkic et al., 2001, 2002; X. Tang et al., 2001) have been published addressing the routing tree construction problem. But all these algorithms are slow and not scalable. We propose an algorithm, which is fast and scalable with problem size. The main idea of our approach is to specify some important high-level features of the whole routing tree so that it can be broken down into several components. We apply stochastic search to find the best specification. Since we need very few high-level features, the size of stochastic search space is small which can be searched in very less time. The solutions for the components are either pregenerated and stored in lookup tables, or generated by extremely fast algorithms whenever needed. Since it is efficient to obtain solutions for components, it is also efficient to construct and evaluate the whole routing tree for each specification. Experimental results show that, for trees of moderate size, our algorithm is at least several hundred times faster than the recently proposed algorithms. Experimental results also show that the trees generated by our algorithm have almost same delay and resource consumption as the trees generated by SP-tree.