Constrained Horn Clauses (CHCs) are an intermediate program representation that can be generated by several verification tools, and that can be processed and solved by a number of Horn solvers. One of the main challenges when using CHCs in verification is the encoding of heap-allocated data-structures: such data-structures are today either represented explicitly using the theory of arrays, or transformed away with the help of invariants or refinement types, defeating the purpose of CHCs as a representation that is language-independent as well as agnostic of the algorithm implemented by the Horn solver. This paper presents an SMT-LIB theory of heap tailored to CHCs, with the goal of enabling a standard interchange format for programs with heap data-structures. We introduce the syntax of the theory of heap, define its semantics in terms of axioms and using a reduction to SMT-LIB arrays and data-types, and discuss its properties and outline possible extensions and future work.
@article{arxiv.2104.04224,
title = {A Theory of Heap for Constrained Horn Clauses (Extended Technical Report)},
author = {Zafer Esen and Philipp Rümmer},
journal= {arXiv preprint arXiv:2104.04224},
year = {2021}
}