Global density smoothing technique for analytical placement algorithm

Cell migration has been widely used in global placement for the highly efficiency in smoothing cells overlap. The current cell migration methods only locally or globally smooth the density without considering the relation between the local and the global density. Furthermore, the cells generally are treated as points with area. In this paper we present a new cell migration technique called CSAGO to even the overlap. CSAGO obtains the movement distance while considering the local and the global density distribution simultaneously. By separating the standard cells and the macro blocks crossing multi-bin, a more smooth migration speed can be obtained. CSAGO has been embedded into the global placement process, experimental result shows that average HPWL have reduced 3% and the total runtime is 1.78 times faster than DPlace.