1. A method comprising: identifying one or more regions of Cobol code having an entry point; selecting a PERFORM instruction to analyze associated with the entry point; determining a PERFORM range for the PERFORM instruction; identifying an instruction that changes control flow in execution of the Cobol code subsequent to the PERFORM instruction; determining flow-affected code resulting from the instruction; determining reachable regions from the one or more regions of the Cobol code for the PERFORM instruction; and forming an adjusted PERFORM range for the PERFORM instruction based on the reachable regions.