Efficient computation of flow insensitive interprocedural summary information

To understand when it is safe to apply a given optimization, a compiler must have explicit knowledge about the impact of executing individual statements on the values of variables accessible to the statements. The impact of a statement is termed its side effect. This paper describes a method for annotating each statement s in a program with a set MOD(s) conraining those variables whose values can be changed as a result of executing s. For statements which contain no procedure calls, the side effects can be determined by simple examination of the statement with some knowledge of the semantics of the source language.