Bisection Based Placement for the X Architecture

Rising interconnect delay and power consumption have motivated the investigation of alternative integrated circuit routing architectures. In particular, the X architecture, which features preferred routing in diagonal directions, has gained a measure of industry support, and has even been validated at 65nm. While there has been extensive study of Manhattan design methods, there are markedly fewer published results for non-Manhattan design. To help fill this gap, we study a patented placement method for the X architecture; to our knowledge, there have been no prior published results for the method. Surprisingly, we find that the patented method in fact performs worse than traditional Manhattan methods - for both Manhattan and X routing metrics. We also present a theoretic formulation which explains why solution quality is degraded. Many groups in industry are evaluating the merits of non-Manhattan routing architectures. By providing concrete experimental results, we hope to improve the accuracy of these evaluations.