How to meet the instruction queue in a pipelined data processor

摘要

PURPOSE: To provide a sequential instruction prefetching method for a data processor using a pipeline provided with a sequential instruction prefetching unit(IPU). ;CONSTITUTION: An instruction queue in an IPU34 is connected to an instruction unit 32 and to the instruction cache 38 of a data processor 10 through a pipeline. A prefetching controller in the IPU34 maintains the flow of prefetched instructions so that the instruction queue can load an instruction of any combination of one word, two words, or three words on the instruction unit 32 connected to the queue through the pipeline. The unit 32 receives an instruction word from the queue and decodes executed operation and instruction length/pipeline movement. A method for filling the instruction queue for avoiding the clogging of the pipeline is avoided by keeping a required number of instruction words in the instruction queue is provided. The method for filling the instruction queue is based on the movement of an instruction pipeline pertaining the activity ratio by means of an instruction order deciding device fro instruction words received from the queue.;COPYRIGHT: (C)1993,JPO