Space-Reduction Strategies for Model Checking Dynamic Software

Effective model-checking of modern object-oriented software systems requires providing support for program features such as dynamically created threads, heapallocated objects and garbage collection. These features have often proven problematic to treat using many previous model-checking frameworks that do not provide sophisticated heap representations and optimizations. In this paper, we define a flexible framework for combined heap and thread symmetry reductions in explicit-state model checking that can be tuned to trade run-time overhead for precision. In addition, we describe various strategies for duplication-reducing state-space encodings for object-oriented heap structures. We have implemented these techniques in Bogor (our extensible software model-checking framework), and we present empirical data to support the effectiveness of these memory reductions on a collection of realistic examples and to demonstrate that they improve upon previous approaches. These techniques, formalized in a group theoretic framework, can be applied to any non-deterministic heap object diagram.