Interprocedural side-effect analysis for incomplete object-oriented software modules

We introduce a new approach to computing interprocedural modification side effects for part of an object-oriented program (e.g., components, libraries or client modules). Our approach consists of first performing a whole-program points-to analysis to such an incomplete program and then applying a so-called mutability analysis (MA) to determine which objects in the program are mutable by unknown code and which references and call sites in the program are complete (since their points-to sets and target methods are statically resolvable). Based on these results, we present a new MA-based interprocedural side-effect analysis for computing the modification side-effects for an incomplete program. Our experimental results show that our mutability analysis enables a variety of pure methods to be detected, yielding the purity information useful in program understanding and debugging. In addition, our MA-based side-effect analysis enables more redundant loads to be removed than a recent TBAA-based PRE algorithm guided by type-based alias analysis (TBAA). Our approach is simple since it is flow-insensitive and achieves these improvements at small costs.