1. A computer program product for use in a data processing system, the computer program product comprising a computer usable medium having computer usable program code for instruction substitution in an application code of an application being loaded during load time, the computer usable program code comprising: computer usable program code for, responsive to identifying the candidate instruction, determining whether a hardware facility of the data processing system is present to execute the candidate instruction; and computer usable program code for, responsive to a determination that the hardware facility is absent from the data processing system, substituting the candidate instruction with a second set of instructions.