Compilation of synchronous observers as code contracts

Abstract

Synchronous languages have long been the standard formalism for modeling and implementing embedded control software in critical domains like avionics, automotive or railway system development. Those languages are equipped with qualified compilers that generate the target final embedded code. An extensively used technique to define the expected behavior is the use of synchronous observers. Those observers are typically used for simulation and testing purposes. However, the information contained in those observers is lost during the compilation process. This makes the verification of expected behavior at code level difficult, since it requires the re-specification of the observer. In this paper, we propose an integrated process in which functional properties expressed at the model level through synchronous observers are compiled as code-level contracts. We also show how these specifications, both at model level and code level could be analyzed via SMT-based model checking, static analysis and runtime verification. We have implemented these techniques in a tool chain targeting embedded systems modeled in Simulink.