Section: New Software and Platforms

The Apron Numerical Abstract Domain Library

Participants : Antoine Miné [correspondent] , Bertrand Jeannet [team PopArt, Inria-RA] .

The Apron library is dedicated to the static analysis of the numerical variables of a program by abstract interpretation. Its goal is threefold: provide ready-to-use numerical abstractions under a common API for analysis implementers, encourage the research in numerical abstract domains by providing a platform for integration and comparison of domains, and provide a teaching and demonstration tool to disseminate knowledge on abstract interpretation.

The Apron library is not tied to a particular numerical abstraction but instead provides several domains with various precision versus cost trade-offs (including intervals, octagons, linear equalities and polyhedra). A specific C API was designed for domain developers to minimize the effort when incorporating a new abstract domain: only few domain-specific functions need to be implemented while the library provides various generic services and fallback methods (such as scalar and interval operations for most numerical data-types, parametric reduced products, and generic transfer functions for non-linear expressions). For the analysis designer, the Apron library exposes a higher-level API with C, C++, OCaml, and Java bindings. This API is domain-neutral and supports a rich set of semantic operations, including parallel assignments (useful to analyze automata), substitutions (useful for backward analysis), non-linear numerical expressions, and IEEE floating-point arithmetic.

The Apron library is freely available on the web at http://apron.cri.ensmp.fr/library/ ; it is distributed under the LGPL license and is hosted at InriaGForge . Packages exist for the Debian and Fedora Linux distributions. In order to help disseminate the knowledge on abstract interpretation, a simple inter-procedural static analyzer for a toy language is included. An on-line version is deployed at http://pop-art.inrialpes.fr/interproc/interprocweb.cgi .

The Apron library is developed since 2006 and currently consists of 130 000 lines of C, C++, OCaml, and Java.

Current and past external library users include the Constraint team (LINA, Nantes, France), the Proval/Démon team (LRI Orsay, France), the Analysis of Computer Systems Group (New-York University, USA), the Sierum software analysis platform (Kansas State University, USA), NEC Labs (Princeton, USA), EADS CCR (Paris, France), IRIT (Toulouse, France), ONERA (Toulouse, France), CEA LIST (Saclay, France), VERIMAG (Grenoble, France), ENSMP CRI (Fontainebleau, France), the IBM T.J. Watson Research Center (USA), the University of Edinburgh (UK).

Additionally, Apron is used internally by the team to assist the research on numeric domains and static analyses by enabling the development of fast prototypes. Specifically, in 2014, Apron has been used to support the design of piece-wise linear ranking function domains to infer termination and functional liveness properties in the implementation of the FuncTion prototype analyzer, and to implement and experiment a new numeric domain for octagonal constraints with absolute values. It has also been used in the introductory course on program verification given by members of the team.