Patent ID: 8015522

Claim:
Non-transitory computer-readable storage media containing software, which when read and executed by a computer, causes the computer to carry out a method for implementing an engineering change order (ECO) by modifying a first integrated circuit (IC) layout for a first IC to produce a second IC layout for a second IC, wherein the first and second ICs include active cell instances interconnected by nets to form subcircuits, and include spare cell instances not interconnected by nets, the method comprising the steps of: a. comparing netlists describing the first and second ICs to identify additions and deletions, wherein additions are subcircuits formed by active cell instances and nets included in the second IC but not in the first IC, and wherein deletions are subcircuits formed by active cell instances and nets included in the first IC but not included in the second IC; b. reclassifying active cell instances of the first IC that form the identified deletions as spare cell instances of the first IC; and c. performing ECO re-synthesis comprising generating a technology independent model depicting circuit behavior of the identified additions and selecting spare cell instances of the first IC to implement the circuit behavior depicted by the technology independent model, and wherein step c comprises the substeps of: c1. identifying partitions of the technology independent model, each of which specifies circuit behavior that can be implemented by any spare cell instance of the first IC not already committed to implementing circuit behavior specified by any other partition of the technology independent model; c2. selecting a partition from among all partitions identified at step c1 that specifies circuit behavior that a spare cell instance of the first IC can implement at a lowest cost as determined by a cost function, and committing that spare cell instance to implement the selected partition in the second IC; c3. modifying the technology independent model to delete the partition selected at step c2; and c4. repeating substeps c1, c2 and c3 until all portions of the technology independent model have been deleted.