OPTIMIZED PROGRAM CODE GENERATOR, A METHOD FOR COMPILING A SOURCE TEXT AND A COMPUTER-READABLE MEDIUM FOR A PROCESSOR CAPABLE OF OPERATING WITH A PLURALITY OF INSTRUCTION SETS

An improved optimization technique is described for a program code for a processor capable of operating on the basis of either one of a plurality of instruction sets in a computer system. The optimization is carried out by the steps of reading said program code of a target program to be optimized, estimating the costs of executable instruction sequences respectively to be obtained by translating said program code on the basis of said plurality of instruction sets; and determining an optimum one of said plurality of instruction sets for translating said program code by evaluating the costs as estimated under a predetermined criteria.