| 摘要 |
PURPOSE:To forecast a branched address at a comparatively high hit rate by controlling the updating of the contents of a branch history table means in accordance with a counted result when a branch instruction is a counting branch instruction. CONSTITUTION:The branch history table (BHT) 410 stores information specifying the address of a branch instruction, a branch enable/disable flag as the forecasting of the execution of the branch instruction and the branched address as a group. A forecasting recognizing circuit 420 checks the coincidence of a really branched address generated at the execution of the branch instruction, the branch enabled/disabled result and the forecasting information of the branch instruction and designates the updating of the contents of the branch history table and the retry of the prefetching of the instruction. An instruction prefetching control circuit 424 controls instruction prefetching operation on the basis of a BHT updating designation signal from the circuit 420 and a branch enable/ disable signal from an instruction execution circuit 407.
|
