1. A method of simulation processing in a data processing system, said method comprising: building an instrumented simulation executable model of a design, said building including compiling one or more hardware description language (HDL) files specifying one or more design entities within the design and one or more instrumentation entities and instantiating instances of the one or more instrumentation entities within instances of the one or more design entities; simulating operation of the design utilizing the instrumented simulation executable model, wherein said simulating includes: each of multiple instantiations of the one or more instrumentation entities generating from one or more signals in at least one instance of the one or more design entities a respective external phase signal representing an occurrence of a particular phase of operation; and instrumentation combining logic generating from external phase signals of the multiple instantiations of the one or more instrumentation entities an aggregate phase signal representing an occurrence of the particular phase.