Demand-Driven Static Backward Slicing for Unstructured Programs
Husni Khanfar, Björn Lisper, Saad Mubeen · Diva portal (Dalarna University Library) · 2019
Backward program slicing identifies the program parts that might influence a particular variable at a program point. A program part (e.g., a statement) can be directly influenced by another part due to its data or control dependence on the later. The classical program slicing approaches are designed to find in advance all the data and control dependencies in the program. This design entails a considerable amount of unnecessary computations because not all the dependencies are required for computing the slice. Demand-driven program slicing approaches try to raise the analysis performance by avoiding the unnecessary computations. However, these approaches cannot address unstructured programs in a demand-driven fashion. On the other hand, the existing techniques that compute the control dependencies in unstructured programs are based on fixed-point iterations, which limits their integration to the demand-driven slicing approaches. Program slicing based on Predicate Code Block (PCB) is a new demand-driven slicing approach that can address only structured programs. This paper presents the first demand-driven technique to compute the control dependencies in unstructured programs. In this regard, the technique uses flow information, location-based information and syntactic structure of the source code. Further, the paper shows how the new technique can be integrated to the PCB-based slicing approach to address unstructured programs.