Abstract:
First order logic with transitive closure, and separation logic enable elegant interactive verification of heap-manipulating programs. However, undecidability results and high asymptotic complexity of checking validity preclude complete automatic verification of such programs, even when loop invariants and procedure contracts are specified as formulas in these logics.
We tackle the problem of procedure-modular verification of reachability properties of heap-manipulating programs using efficient decision procedures that are complete: that is, a SAT solver must generate a counterexample whenever a program does not satisfy its specification. By (a) requiring each procedure modifies a fixed set of heap partitions and creates a bounded amount of heap sharing, and (b) restricting program contracts and loop invariants to use only deterministic paths in the heap, we show that heap reachability updates can be described in a simple manner. The restrictions force program specifications and verification conditions to lie within a fragment of first-order logic with transitive closure that is reducible to effectively propositional logic, and hence facilitate sound, complete and efficient verification.
We implemented a tool atop Z3 and report on preliminary experiments that establish the correctness of several programs that manipulate linked data structures.
This work was presented at POPL’14, and is joint work with Shachar Itzhaky (Tel Aviv University), Anindya Banerjee (IMDEA Software Institute), Neil Immerman (University of Massachusetts), Aleksandar Nanevski (IMDEA Software Institute), Mooly Sagiv (Tel Aviv University).
Short bio:
Ori Lahav completed his PhD in computer science at Tel Aviv University under the supervision of Prof. Arnon Avron. In his PhD, Ori explored syntax-semantics connections in general families of Gentzen-type proof calculi for various non-classical logics. He is currently a postdoc with Prof. Mooly Sagiv in Tel Aviv University, working in the ERC funded project “Verifying and Synthesizing Software Compositions”.
Contact:
The speaker will be at Imperial for the whole day. Contact Sergio Maffeis if you would like to arrange a meeting.