Lookahead scanning and cracking of microcode instructions in a dispatch queue

摘要

An apparatus and method for avoiding bubbles and maintaining a maximum instruction throughput rate when cracking microcode instructions. A lookahead pointer scans the newest entries of a dispatch queue for microcode instructions. A detected microcode instruction is conveyed to a microcode engine to be cracked into a sequence of micro-ops. Then, the sequence of micro-ops is placed in a queue, and when the original microcode instruction entry in the dispatch queue is selected for dispatch, the sequence of micro-ops is dispatched to the next stage of the processor pipeline.