Resurrecting Infeasible Clock-Gating Functions

In this paper we consider the problem of exploiting infeasible clock gating functions. Analysis of industrial designs reveals a large margin of potential for power saving based on clock gating functions that initially appear to be useless due to timing violation or excessive power consumption. We propose two optimization techniques for resurrecting such functions that can be used as a generic post-processing phase in an automatic clock gating tool. The first provides timing-aware approximation and the second aims at generating large gating domains by clustering similar clock gating functions. Our experimental results show that the combination of these two techniques yields an additional power saving of up to 78% in industrial designs.