Program slicing based on data-flow computation of path dependence flow graphs

Abstract

Program slicing is a technique to extract from a program a set of statements (referred to as a slice) that have certain properties; such techniques are widely used, for example, for simplification and maintenance of software. This paper proposes a particular method to generate a slice that is formally represented by using a path dependence flow graph (PDFG), namely, by means of interpretive execution of the PDFG based on data-flow computation (1). Since the proposed method is a generalization of the conventional method of interpretive execution of PDFG based on data-flow computation, the same scheme of computation control can be employed as is used in other techniques of PDFG analysis, for example, infeasible path detection (2). The slicing algorithm is specified for nodes in the form of local rules. Therefore, by partially modifying those rules, new varieties of slices can be easily obtained, for example, more precise slices (3). During firing control in data-flow computation, executable nodes are found, and slice is generated simply by consecutive execution of rules at those nodes, which implies simple computation control (4). Since control of slicing can be distributed among nodes, parallel processing is possible (5). A generalized method that offers generation of slices not obtainable by conventional methods is proposed. © 1998 Scripta Technica, Syst Comp Jpn, 28(11): 22–33, 1997