1. A non-transitory computer program product for employing extended registers, wherein instructions include at least one register field having a register extension bit, the register field being non-contiguous with the register extension bit, the non-transitory computer program product comprising a tangible storage medium readable by a processor and storing instructions for execution by the computer for performing a method comprising: decoding an instruction for execution, by the processor, the instruction comprising an opcode, one or more register fields for indexing into a corresponding register, a plurality of register extension bits, and an extended opcode, each register extension bit for concatenating as a high order bit to a register field of a corresponding location in the instruction to form an extended register field; executing the instruction comprising: for each of said one or more register fields, concatenating, by the processor, a register extension bit as high order bit to a corresponding, non-contiguous register field to form contiguous extended register field; and performing a function defined by the opcode fields of the instruction using operands of said one or more extended registers corresponding to said extended register fields.