Flexible SAT-based framework for incremental bounded upgrade checking

Software undergoes a myriad of minor changes along its lifecycle. Each evolved transformation of a program is expected to preserve important correctness and security properties, in particular confirmed by a software model checking tool. However, it may be extremely resource- and time-consuming to repeat entire model checking for each new version of the program. As a possible solution to this problem, we propose to conduct incremental analysis of a new program version by reusing efforts of bounded model checking of the previous program version. Our approach maintains over-approximations of the bounded program behaviors by means of function summaries derived using Craig interpolation. For each new version, these summaries are used to localize the scope of model checking. A benefit of this approach is that the cost of the upgrade checking depends on the change impact between the two versions. If the change impact is relatively small, then the incremental check can drastically outperform the model checking the new program version from scratch. We implemented the approach in scope of the SAT-based bounded model checker for C, eVolCheck. The evaluation of eVolCheck confirms that incremental changes can be verified efficiently for different classes of industrial programs.