Data flow analysis is well understood at the intra-procedural level and efficient algorithms are available. When inter-procedural mechanisms such as recursion, procedure nesting, and pass-by-reference parameters are introduced, the data flow problems become more difficult. Let ISIZE be the size of the problem and OSIZE be the size of the resulting data flow relation. A 0(ISIZE+OSIZE) algorithm is demonstrated for the existential summary data flow problem.
Meyers, Eugene W., "A Precise and Efficient Algorithm for Determining Existential Summary Data Flow Information ; CU-CS-175-80" (1980). Computer Science Technical Reports. 173.