Method for identifying removable inverters in an ic design

Abstract

An integrated circuit design includes a description of a net for distributing a signal from a root node to one or more leaf nodes downstream of the root node. Some segments of the net include inverters and some segments branch into other segments. The IC design is processed to determine a maximum number of inverters that can be removed from the net without affecting a logic state of the signal as it arrives at the leaf nodes. For each segment of the net other than segments terminating on root or leaf nodes two corresponding data sets are generated: one data set indicates a maximum number of inverters that may be removed downstream of its corresponding segment without altering the logic state of the signal at any downstream leaf node, and the other data set indicates a maximum number of downstream inverters that may be removed that will alter the logic state of the signal arriving at every downstream leaf node. Each data set points to all data sets corresponding to segments immediately downstream of the data set's corresponding segment, so that the data sets for all segments form a decision tree that may be traversed to determine which inverters must be removed to maximize the number of inverters removed from the net without affecting the logic state of the signal arriving at each leaf node.