1. A method of processing in a data processing system, said method comprising: receiving one or more hardware description language (HDL) files that specify a plurality of hierarchically arranged design entities defining a design to be simulated and that specify an instrumentation entity for monitoring simulated operation of the design; in response to receiving the one or more HDL files, building an instrumented simulation executable model of the design in accordance with the one or more HDL files, said building including: compiling the one or more hardware description language (HDL) files specifying the plurality of hierarchically arranged design entities defining the design and instantiating at least one instance of each of the plurality of hierarchically arranged design entities; instantiating an instance of the instrumentation entity within an instance of a particular design entity among the plurality of design entities and, based upon a reference in a first instrumentation statement in the one or more HDL files, logically attaching an input of the instance of the instrumentation entity to a first input source within the design that is outside the scope of the particular design entity; in response to detecting that a second instrumentation statement in the one or more HDL files directs attachment of instrumentation to a second input source not present in the design, removing instrumentation logic in a cone of influence associated with the second input source; and storing the instrumented simulation executable model of the design in data storage.