An efficient data structure for must-alias analysis

A must-alias (or “definite-alias”) analysis computes sets of expressions that are guaranteed to be aliased at a given pro- gram point. The analysis has been shown to have significant practical impact, and it is actively used in popular research frameworks and commercial tools. We present a custom data structure that speeds up must-alias analysis by nearly two orders of magnitude (while computing identical results). The data structure achieves efficiency by encoding multiple alias sets in a single linked structure, and compactly representing the aliasing relations of arbitrarily long expressions. We ex- plore the data structure’s performance in both an imperative and a declarative setting and contrast it extensively with prior techniques. With our approach, must-alias analysis can be performed efficiently, over large Java benchmarks, in under half a minute, making the analysis cost acceptable for most practical uses.