On the Accuracy of Forward Dynamic Slicing and Its Effects on Software Maintenance

Dynamic slicing is a practical and popular analysis technique used in various software-engineering tasks. Dynamic slicing is known to be incomplete because it analyzes only a subset of all possible executions of a program. However, it is less known that its results may inaccurately represent the dependencies that occur in those executions. Some researchers have identified this problem and developed extensions such as relevant slicing, which incorporates static information. Yet, dynamic slicing continues to be widely used, even though the extent of its inaccuracy is not well understood, which can affect the benefits of this analysis. In this paper, we present an approach to assess the accuracy of forward dynamic slices, which are used in software maintenance and evolution tasks. Because finding all actual dependencies is an undecidable problem, our approach instead computes bounds of the precision and recall of forward dynamic slices. Our approach uses sensitivity analysis and execution differencing to find a subset of all program statements that truly depend at runtime on another statement. Using this approach, we studied the accuracy of many forward dynamic slices from a variety of Java applications. Our results show that forward dynamic slicing can have low recall -- for dependencies in the analyzed executions -- and some potential imprecision. We also conducted a case study that shows how this inaccuracy affects a software maintenance task. To the best of our knowledge, ours is the first work that quantifies the intrinsic limitations of dynamic slicing.