DYNAMICALLY LOADABLE PATTERN HISTORY CHART IN MICROPROCESSOR

摘要

PROBLEM TO BE SOLVED: To provide a method for dynamically predicting the branch instruction of a microprocessor operating under a multitask environment by holding predicted information based on its own branch pattern history. SOLUTION: A fetching unit 26 is branched with a branch target buffer 56 and plural pattern history charts 53. A selection logic 80 receives a signal indicating the kind of a program including an instruction for each branch instruction, selects one pattern history chart 53, and generates a prediction code according to a branch history field BH in the entry of the branch target buffer 56 corresponding to an instruction address by using the pattern history chart. At the time of task switching, the contents of more than one pattern history charts 53 are stored in a task state segment corresponding to an interrupted task, and an entry from the task state segment of a new task is loaded to the patter history chart 53.