Constructing fast and cycle-accurate simulators for configurable accelerators using C++ templates

To quickly prototype accelerator/compiler co-designs, fast and highly accurate architectural simulators are indispensable. They must be fast to keep design iteration times low; they must be highly accurate to make simulation results meaningful. In this paper, we describe how to construct such fast, cycle-accurate simulators from an architectural model by using C++ templates. Not only are templates fully resolved at compile time, thus offering ample opportunity for optimization, they also aptly mirror synthesis-time parameterization of accelerators. For each hardware component, we encode these architecture parameters in a C++ type and construct a class templated on this type. Hierarchically composing the component classes then yields the overall simulator. To demonstrate our constructed simulators' speedup, we construct two simulators for a lightweight VLIW processor, one with, one without templates, and measured their performance: the templated simulator is about 4.85 times faster. Their execution speed makes our simulators well-suited for compiler validation and prototyping accelerator features.