APPARATUS AND METHOD FOR EXECUTION OF BRANCH INSTRUCTIONS

摘要

In a pipelined data processing system using microinstructions from a control unit, the method of implementing a conditional branch macroinstruction involves the sequence of microinstructions in which the potential instruction sequence is prepared for execution while the original instruction sequence continues in execution even though the results of the condition testing are not determined. When the condition is determined to be false, the instruction sequence in execution is continued and the retrieved instruction sequence is not activated. When the condition is determined to be true, the new instruction sequence can be executed immediately and the results of the original (and erroneous) sequence can be discarded. In conditional branch macroinstructions where the probability of branching is large, an unconditional branch instruction is executed to place the most probable instruction sequence in immediate execution and the conditional branch instruction, described above, is executed to determine the result of the condition.