In a computing system running an environment for designing operation of circuitry, at least the following are performed for providing simulations and evaluations of one or more user-defined modules of circuitry including one or more pipeline stages in a pipeline. A model of the pipeline is automatically generated by using a pipeline block diagram, where the model is generated in a high-level modeling language able to perform simulations of circuitry with the pipeline. An interface is automatically generated between the one or more user-defined modules and the generated model of the pipeline, the interface including access to the pipeline, wherein the pipeline access allows the one or more user-defined modules to interact indirectly. Evaluation is performed of the one or more user-defined modules using the automatically generated model of the pipeline and the automatically generated interface. Methods, apparatus, and computer program products are disclosed.