A precise demand-driven definition-use chaining algorithm

Abstract

This paper describes a new demand-driven technique that is able to identify both direct and indirect realizable data-dependencies between statements in the investigated code. Involving control-dependencies too our method thus can also be extended to perform precise forward and backward slicing of computer programs.The presented interprocedural algorithm considers realizable program paths when exploring individual definition-use chains by introducing backtrack information for traditional reaching definitions. Hence our method is able to reveal deep and accurate information about very large programs on demand that makes it effectively applicable in either regression testing, debugging and program analysis.

A demand‐driven approach to slicing legacy COBOL systems

“…[30] endif [31] if m uses x then // Rule 2 [32] Mark m [33] foreach defined variable z influenced by use of x do [34] Propagate (RD z y , m) [35] endfor [36] if m is a predicate then // Rule 5 [37] Propagate (RD C y , m) [38] endif [39] endif [40] endfor [41] endswitch [42] else // control tokens [43] switch n [44] case call site for called procedure P: // Rule 3 [45] Propagate (RD C C , entryNodeOf(P)) [46] foreach z | RD z C ∈ exitNodeOf(P) do [47] Propagate (RD z y , returnSiteOf(n)) // These rules are summarized below:…”

“…A former paper of the authors [41] presented a token propagation-based method to compute realizable definition-use chains. That method does not consider control dependences, parameter passing, and is not fully demand-driven (relies on kill sets computed in advance).…”