Global value numbering for redundancy detection: a simple and efficient algorithm

Global Value Numbering (GVN) is a method for detecting equivalence among program expressions. Here we consider the problem of GVN in the context of redundancy detection and present a simple, polynomial time algorithm for the same. The basic idea is to use the concept of value expression - an abstraction of a set of expressions - enabling a representation of the equivalence information which is compact and simple to manipulate. The algorithm detects expression equivalences that are required for identifying value based redundancies. In addition, it achieves completeness in detecting equivalence among variables.