1. Computer software resident on a tangible computer readable storage medium and operable when executed by a computer to perform program code conversion comprising the steps of: (a) establishing one or more abstract registers, each corresponding to a unique flag parameter (operand) used by a flag-affecting instruction which selectively modifies a flag; (b) generating an intermediate representation (IR) tree for a selected instruction sequence, said selected instruction sequence followed by a flag-using instruction which uses said flag, said IR tree depending from the one or more of said abstract registers; (c) responding to a first flag-affecting instruction in said selected instruction sequence to cause a flag parameter abstract register to refer to said IR tree generated at step (b); and (d) resolving, in response to detecting said flag-using instruction, a status of said flag with respect to said flag parameter abstract register.