Field-Sensitive Program Slicing

Abstract

The granularity level of the program dependence graph (PDG) for composite data structures (tuples, lists, records, objects, etc.) is inaccurate when slicing their inner elements. We present the constrainededges PDG (CE-PDG) that addresses this accuracy problem. The CE-PDG enhances the representation of composite data structures by decomposing statements into a subgraph that represents the inner elements of the structure, and the inclusion and propagation of data constraints along the CE-PDG edges allows for accurate slicing of complex data structures. Both extensions are conservative with respect to the PDG, in the sense that all slicing criteria (and more) that can be specified in the PDG can be also specified in the CE-PDG, and the slices produced with the CE-PDG are always smaller or equal to the slices produced by the PDG. An evaluation of our approach shows a reduction of the slices of 11.67%/5.49% for programs without/with loops.

Analysis Techniques for Software Maintenance

“…The chapter details how to compute the CE-PDG from the PDG, how to join CE-PDGs to build the CE-SDG, and how to adapt the slicing algorithm to slice both graphs. Part of the content introduced in the chapter (the CE-PDG part) has been extracted from [61] while the CE-SDG part is original from this thesis.…”

“…• In Chapter 5, we propose a new fine-grained graph representation for programs, the Expression Dependence Graph (EDG), built from the AST of the program, where each literal of the source code is represented as a node of the graph. This chapter further elaborates the idea proposed in [63], introducing a set of situations where the SDG generates inaccurate slice, accurately slicing them with the use of the EDG.…”

“…• In Chapter 4 we proposed a new approach for the representation and slicing of composite data structures, the Constrained-Edges Program Dependence Graph (CE-PDG) [61]. First of all, we augmented the PDG representation for explicit composite data structures by adding AST nodes representing inner components.…”

“…• Chapter 5 presented an alternative graph representation for programs, the Expression Dependence Graph (EDG), which can be used by any programming paradigm and language [63]. The EDG provides a fine-grained program representation, where each node corresponds with an AST node of the program instead of representing a program statement.…”