Cloning techniques for hierarchical compaction

A method for efficiently performing hierarchical compaction in the presence of over the cell routing (OTCR) is described. By treating the OTCR objects as part of the cells they overlap, the amount of interaction between cells in the hierarchy is reduced. This method eliminates the need to make all objects within a cell that interact with OTCR into ports. An explosion in the complexity of the problem that needs to be solved via linear programming (LP) is thus avoided. Computation is shifted away from LP and into the graph domain where efficient and accurate solution methods have been demonstrated.<>