Patent ID: 8196081

Claim:
A processor-implemented method for routing of a partially routed circuit design having modified and unmodified signals from a previous version of the circuit design, comprising: determining the modified signals of the partially routed circuit design, the modified signals including new, changed, and deleted signals from the previous version of the circuit design; applying, by the processor, a first set of routing constraints to the unmodified signals of the circuit design, the routing constraints preventing reroute of the unmodified signals; determining for each logic block of the circuit design, a number of the modified signals and a number of the unmodified signals connected to the logic block; in response to one of the logic blocks having a ratio of the number of modified signals to the number of unmodified signals greater than a threshold ratio, removing, by the processor, the routing constraints from one or more of the unmodified signals of the one of the logic blocks; and incrementally routing, by the processor, the partially routed circuit design according to the routing constraints.