Cloning techniques for hierarchical compaction
Ravi Varadarajan, Cyrus S. Bamji · International Conference on Computer Aided Design · 1992
True hierarchical compaction maintains input layout hierarchy as well as abutment constraints between cells. The bottleneck for hierarchical compaction is the time taken to analyze the system of equations which must be solved via linear programming methods. Because of the computational complexity of linear programmin it is essential to keep this system of equations as smal?as possible. With over the cell routing the amount of interaction between levels of hierarch increases considerably. This causes a substantial rise in tXe number of constraints and so the time taken by the compaction rocess is significantly increased. A novel method for hanAing over the cell routing, termed cloning, is described. This approach allows for efficient compaction of arbitrary hierarchies containing ouer the cell routing without significantly degrading the run time performance of the hierarchical compactor. 1 Overview 1.1 Background