Benjamin Farinier

Arrays Made Simpler: An Efficient, Scalable and Thorough Preprocessing

Benjamin Farinier, Robin David, Sébastien Bardin, and Matthieu Lemerre

The theory of arrays has a central place in software verification due to its ability to model memory or data structures. Yet, this theory is known to be hard to solve in both theory and practice, especially in the case of very long formulas coming from unrolling-based verification methods. Standard simplification techniques à la read-over-write suffer from two main drawbacks: they do not scale on very long sequences of stores, and they miss many simplification opportunities because of a too crude syntactic (dis-)equality reasoning.

We propose a new approach to array constraint simplification based on a new dedicated data structure together with original simplifications and low-cost reasoning. The technique is efficient, scalable and it yields significant simplification. The impact on formula resolution is always positive, and it can be dramatic on some specific classes of problems, e.g. very long formula or binary-level symbolic execution. While currently implemented as a preprocessing step, the approach would benefit from a deeper integration inside a dedicated array solver.

[ binsec.tar.gz | bench.tar.gz ]