Abstract: One embodiment of the present invention provides a system that speeds up timing analysis by reusing delays computed for isomorphic subcircuit. During operation, the system receives a circuit block to be analyzed, wherein the circuit block is in the form of a netlist. The system then subdivides the circuit block into a set of subcircuits. The subcircuits are then partitioned into equivalence classes, which contain subcircuits which are topologically isomorphic to each other. Next, the system performs a timing analysis by tracing paths through a timing graph for the circuit block. During this timing analysis, whenever a delay is required for a subcircuit, the system determines if a corresponding delay has been already computed for the equivalence class associated with the subcircuit. If so, the system reuses the delay. If not, the system computes the delay for the subcircuit, and then associates the computed delay with the equivalence class so that the computed delay can be reused for isomorphic subcircuits.

Abstract: A method and apparatus for determining the layout of an integrated circuit, in accordance with timing constraints, by means of sizing the buffers in the layout. A nominal netlist for the layout of the integrated circuit is used to determine critical paths through the circuit. The time-critical paths are determined and the instances of the buffers along the path are resized so that the time delays in the time-critical paths are either brought within the predetermined timing criteria, or no further improvement in any time-critical path is possible.