Analysis and Transformations for Efficient Query-Based Debugging

This paper describes a framework that supports powerful queries in debugging tools, and describes in particular the transformations, alias analysis, and type analysis used to make the queries efficient. The framework allows queries over the states of all objects at any point in the execution as well as over the history of states. The transformations are based on incrementally maintaining the results of expensive queries studied in previous work. The alias analysis extends the flow-sensitive intraprocedural analysis to an efficient flow-sensitive interprocedural analysis for an object-oriented language with also a form of context sensitivity. We also show the power of the framework and the effectiveness of the analyses through case studies and experiments with XML DOM tree transformations, an FTP client, and others. We were able to easily determine the sources of all injected bugs, and we also found an actual bug in the case study on the FTP client.