Incremental analysis of evolving alloy models

Abstract

Alloy is a well-known tool-set for building and analyzing software designs and models. Alloy’s key strengths are its intuitive notation based on relational logic, and its powerful analysis engine backed by propositional satisfiability (SAT) solvers to help users find subtle design flaws. However, scaling the analysis to the designs of real-world systems remains an important technical challenge. This paper introduces a new approach, iAlloy, for more efficient analysis of Alloy models. Our key insight is that users often make small and frequent changes and repeatedly run the analyzer when developing Alloy models, and the development cost can be reduced with the incremental analysis over these changes. iAlloy is based on two techniques – a static technique based on a lightweight impact analysis and a dynamic technique based on solution re-use – which in many cases helps avoid potential costly SAT solving. Experimental results show that iAlloy significantly outperforms Alloy analyzer in the analysis of evolving Alloy models with more than 50% reduction in SAT solver calls on average, and up to 7x speedup.