PROCESSOR AND METHOD FOR SPECULATIVELY EXECUTING CONDITION BRANCHING COMMAND BY USING SELECTED ONE OF PLURAL BRANCH PREDICTION SYSTEM

PROBLEM TO BE SOLVED: To provide an improved processor and method for speculatively executing a condition branching command by using selected one of plural branch prediction systems. SOLUTION: The processor and the method for speculatively executing a branch command using a selected branch prediction system is disclosed. The processor has one or plural executing units for executing a command which includes a branch processing unit 18 for executing a branch command. In the branch processing unit 18, a selective logic mechanism 66 for selecting one of plural branch prediction systems, and a branch predicting unit for predicting a solution of a conditional branch command using the selected branch prediction system are included. In the branch processing unit 18, an executing function for speculatively executing the conditional branch command based on the prediction is further included. The selective logic mechanism 66 selects a branch prediction system for predicting the following conditional branch command based on the predicted result, and as a result, branch predictive accuracy is improved.