Abstract: Methods for modifying power use of a semiconductor device include receiving, at one or more processors, an activity stream of a simulation of a semiconductor device, the activity stream comprising a stream of signals. Using the one or more processors, integrated circuit actions are recognized from the activity stream, each integrated circuit action representing an abstraction of work done by the semiconductor device. The processor(s) determine one or more values associated with the integrated circuit actions. A model of power use is generated for the semiconductor device, the model based at least in part on the recognized integrated circuit actions and the associated values. Based on an output of the model, power use of the semiconductor device is modified. Other methods and systems related to determining, modeling, and predicting power/energy use of semiconductor devices are also disclosed.