Apparatus, system and method for quickly determining an oldest instruction in a non-moving instruction queue

摘要

An apparatus, system and method for quickly determining an oldest instruction in a non-moving instruction queue of a processor are provided. Particularly, instructions are stored, one at a time at a clock cycle, in the non-moving queue. At every clock cycle, a present status of the instructions in the queue is recorded. Using the present status of the instructions in the queue in conjunction with previously recorded statuses of the instructions, the oldest instruction in the queue is determined. The status of the instructions in the queue includes whether or not the instruction has been issued for execution as well as whether or not it is known that the issued instruction has been accepted for execution.