1. A data processing system that performs operations responsive to a program including a plurality of instructions, the instructions including arithmetic instructions at least a first and second test instruction and at least a first and second branch instruction that determine an intended sequence of execution of the instructions within the program responsive to results of the first and second test instructions respectively, the system comprising: an operation unit that executes the instructions by performing operations responsive to the instructions, the operation unit being capable of executing instructions out of order in which they appear in the program; a branch prediction unit that speculates a first intended sequence of execution of the instructions responsive to the first branch instruction and speculates a second intended sequence of execution of the instructions responsive to the second branch instruction, the first and second intended sequences affecting sequence of execution of instructions by the operation unit; an evaluation unit that determines, responsive to execution of the first test instruction by the operation unit, whether the branch prediction unit has speculated the first intended sequence correctly, wherein the branch prediction unit speculates the second intended sequence prior to execution of the first test instruction; a repair unit that, upon a determination by the evaluation unit that the branch unit has speculated either the first intended sequence or the second intended sequence incorrectly, nullifies the effects of instructions of the incorrectly speculated intended sequence; a register unit that stores data on which to operate; a temporary storage unit that stores the results of operations performed responsive to arithmetic instructions and for storing each result in a unique location; and a retirement unit that retires each unnullified instruction in the order it appears in the program, the retirement unit retiring an arithmetic instruction after the result of an operation performed responsive to the instruction are stored in the temporary storage unit, by removing the result therefrom and updating the register unit with the result.