Program Slicing

The concept of static program slicing was first introduced by Weiser. Ottenstein et al. indicated that an intraprocedural slice can be found in linear time by traversing a suitable graph representation of the program referred to as the program dependence graph (PDG). Horwitz et al. introduced algorithms to construct interprocedural slices by extending the program dependence graph to a supergraph of the PDG referred to as the system dependence graph (SDG). This extension captures the calling context of procedures. In a previous paper, we demonstrated that a parse-tree-based SDG provides us with ‘‘smaller’’ and therefore more precise slices than a statement-based SDG. Furthermore, we described extensions to the SDG in order to handle particular constructs in a language that is a subset of ANSI C. In this paper, we will describe a new method for the calculation of transitive dependences and therefore build a SDG that does require neither the calculation of the GMOD and GREF sets nor the construction of a linkage grammar and the corresponding subordinate characteristic graphs of the linkage grammar’s nonterminals. Additionally, we illustrate the versatility of the SDG as an internal program representation by briefly presenting a tool that we have developed that permits slicing, dicing, and ripple analyzing in addition to other software engineering activities to be performed on programs written in a subset of ANSI C. This report is an extension of our previous report published in December 1991.