| 摘要 |
PURPOSE:To prefetch a branch instruction by forecasting the prefetch, by holding branch direction information in a branch direction control memory having the same structure with a buffer memory. CONSTITUTION:The tendency that an optional branch instruction executed several times is branched frequently in the same direction every time it is executed is utilized to store its branch direction, determined in the execution of the branch instruction, in a branch direction control memory 20 every time the instruction is executed. Prior to the execution, the instruction, where prefetched from a buffer memory 40 is prefetched by considering the possibility of branch in the same direction as before to be high. A prefetch control part 10 considers the possibility of branch in the same direction as before to be high according to the contents of a branch direction register 70 indicating the branch direction (success or failure) when the same branch instruction is executed, thus prefetching the instruction. |
