3069	 A Practical Interprocedural Data Flow Analysis Algorithm	 A new interprocedural data flow analysis algorithm is presented and analyzed. The algorithm associates with each procedure in a program information about which variables may be modified which may be used and which are possibly preserved by a call on the procedure and all of its subcalls. The algorithm is sufficiently powerful to be used on recursive programs and to deal with the sharing of variables which arises through reference parameters. The algorithm is unique in that it can compute all of this information in a single pass not requiring a prepass to compute calling relationships or sharing patterns. The algorithm is asymptotically optimal in time complexity. It has been implemented and is practical even on programs which are quite large. Data flow analysis global flow analysis optimization side effects relations reference parameters incarnations
