Power-aware issue queue design for speculative instructions

Speculatively issued instructions may be particularly sensitive to increases in pipeline depth. Our results indicate that as pipeline depth increases, speculation increases the percentage of issue queue instructions that are waiting to be potentially re-issued in case of a mis-speculation. To compensate, issue queues are larger and thus more power hungry. We propose an alternative design called the Dual Issue Queue that retains pre- and post-issue instructions in separate, smaller queues, saving 18% of issue queue power dissipation without degrading performance.