Advanced slicing of sequential and concurrent programs

Program slicing is a technique to identify statements that may influence the computations in other statements. Despite the ongoing research of almost 25 years, program slicing still has problems that prevent a widespread use: Sometimes, slices are too big to understand and too expensive and complicated to be computed for real-life programs. The presented thesis shows solutions to these problems: It contains various approaches which help the user to understand a slice more easily by making it more focused on the user´s problem. All of these approaches have been implemented in the VALSOFT system and thorough evaluations of the proposed algorithms are presented. The underlying data structures used for slicing are program dependence graphs. They can also be used for different purposes: A new approach to clone detection based on identifying similar subgraphs in program dependence graphs is presented; it is able to detect modified clones better than other tools. In the theoretical part, this thesis presents a high-precision approach to slice concurrent procedural programs despite the fact that optimal slicing is known to be undecidable. It is the first approach to slice concurrent programs that does not rely on inlining of called procedures.