Code difference visualization by a call tree

Understanding modifications to a software product is essential in software maintenance. To help programmers understand modifications, especially how code changes in a refactoring, this paper presents a semi-automated dynamic analysis to compare two revisions of a product. The approach basically detects “similar but different” sub-tree pairs between call trees from execution traces of the two revisions and then draws up a call graph of the pairs. In addition, pruning techniques or heuristics are used to make the graph smaller and easier to be understood.