Transferring State-of-the-Art Immutability Analyses: Experimentation Toolbox and Accuracy Benchmark

Immutability analysis is important to software testing, verification and validation (V&V) because it can be used to identify independently testable functions without side-effects. Existing tools for immutability analysis are largely academic prototypes that have not been rigorously tested for accuracy or have not been maintained and are unable to analyze programs written in later versions of Java. In this paper, we re-implement two prominent approaches to inferring the immutability of an object: one that leverages a points-to analysis and another that uses a type-system. In addition to supporting Java 8 source programs, our re-implementations support the analysis of compiled Java bytecode. In order to evaluate the relative accuracy, we create a benchmark that rigorously tests the accuracy boundaries of the respective approaches. We report results of experiments on analyzing the benchmark with the two approaches and compare their scalability to real world applications. Our results from the benchmark reveal that points-to based approach is more accurate than the type inference based approach in certain cases. However, experiments with real world applications show that the points-to based approach does not scale well to very large applications and a type inference based approach may offer a scalable alternative.