Viper: A Verification Infrastructure for Permission-Based Reasoning

Abstract

The automation of verification techniques based on first-order logic specifications has benefitted greatly from verification infrastructures such as Boogie and Why. These offer an intermediate language that can express diverse language features and verification techniques, as well as back-end tools: in particular, verification condition generators. However, these infrastructures are not well suited to verification techniques based on separation logic and other permission logics, because they do not provide direct support for permissions and because existing tools for these logics often favour symbolic execution over verification condition generation. Consequently, tool support for these logics where available is typically developed independently for each technique, dramatically increasing the burden of developing automatic tools for permission-based verification. In this paper, we present a verification infrastructure whose intermediate language supports an expressive permission model natively. We provide tool support including two back-end verifiers: one based on symbolic execution, and one on verification condition generation; an inference tool based on abstract interpretion is currently under development. A wide range of existing verification techniques can be implemented via this infrastructure, alleviating much of the burden of building permission-based verifiers, and allowing the developers of higher-level reasoning techniques to focus their efforts at an appropriate level of abstraction.