A Constraint Solver for Heaps with Separation

This paper introduces a constraint language H for finite partial maps (a.k.a. heaps) that incorporates the notion of separation from Separation Logic. The motivation behind H is reasoning over heap manipulating programs using constraint-based symbolic execution. For this we present a modest extension of Hoare Logic that inherits many of the benefits from Separation Logic, such as local reasoning, but encodes heap operations as H-formulae. Next we present a sound and complete solving algorithm for quantifier-free H-formulae, and an implementation that has been integrated into a Satisfiability Modulo Theories (SMT) framework. We experimentally evaluate the implementation against Verification Conditions (VCs) generated from symbolic execution of large programs. In particular, we mitigate the path explosion problem using subsumption via interpolation.