Efficient update of program dependence graphs

Abstract

The program dependence graph (PDG) is a directed graph expressing dependencies between statements in a program. By tracing the PDG edges, it is possible to extract a set of statements relating to any statement (program slice, slice). The PDG and slices are used for debugging, maintenance, and similar applications. In general, PDG computing is time-consuming. However, previously, the entire PDG had to be recomputed each time the program was updated, even when the program was frequently updated, and the slices were obtained. Therefore, in the current study, the authors propose an update algorithm, which confines updating to the PDG section corresponding to the program section being updated. It is expected that recomputing time will be reduced, and that debugging will be more efficient. In addition, we have realized the proposed technique in an existing debugging aid system, and have confirmed its efficiency. © 1998 Scripta Technica, Syst Comp Jpn, 29(14): 58–67, 1998