Reducing the overhead of assertion run-time checks via static analysis

Abstract

In order to aid in the process of detecting incorrect pro- gram behaviors, a number of approaches have been proposed which include a combination of language-level constructs (such as procedure-level assertions/contracts, program-point assertions, gradual types, etc.) and associated tools (such as code analyzers and run-time verification frameworks). How- ever, it is often the case that these constructs and tools are not used to their full extent in practice due to a number of limitations such as excessive run-time overhead and/or limited expressiveness. Verification frameworks that com- bine static and dynamic techniques offer the potential to bridge this gap. In this paper we explore the effectiveness of abstract interpretation in detecting parts of program speci- fications that can be statically simplified to true or false, as well as the impact of such analysis in reducing the cost of the run-time checks required for the remaining parts of these specifications. Starting with a semantics for programs with assertion checking, and for assertion simplification based on static analysis information, we propose and study a number of practical assertion checking modes, each of which rep- resents a trade-off between code annotation depth, execu- tion time slowdown, and program safety. We also propose techniques for taking advantage of the run-time checking se- mantics to improve the precision of the analysis. Finally, we study experimentally the performance of these techniques. Our experiments illustrate the benefits and costs of each of the assertion checking modes proposed as well as the benefit of analysis for these scenario.