1. A computer program product comprising: one or more computer-readable storage media and program instructions stored on at least one of the one or more computer-readable storage media, the program instructions comprising: program instructions to determine whether a first procedure within a first program has access to one or more variables declared outside the scope of the first procedure; program instructions to generate a call graph computation that includes searching from a vertex representing the first procedure until one or more of a plurality of criteria that are configured for pessimistic aliasing cause the first procedure to be flagged; program instructions to determine whether the first procedure within the first program meets a first criterion, wherein the first criterion is included in the plurality of criteria; and responsive to the determination, program instructions to determine whether to flag the first procedure for pessimistic aliasing.