Speculative Issue Logic

In order to enhance the performance of a computer, most modern processors use superscalar architecture and raise the clock frequency. Superscalar architecture can execute more than one instruction per each cycle. The amount of instruction level parallelism will become more and more important when superscalar issue width is increased. With hardware support, instructions can be speculatively waked up. The more instructions are waked up, the more ILP is exploited, hence IPC is increased. Through speculative aspect can be adopted to wakeup more instructions. But the ILP is still limited by the true data dependency. In this paper we proposed the speculative wakeup logic with value prediction mechanism to overcome the data dependency that will exploit instruction level parallelism. And in order to reduce the recovery frequency, we also propose priority-based select logic with two bit counter. In our experiment, our model will enhance performance by 18.02%.

• Type: Conference
• Year: 2005
• Where: APCSAC
• Authors: You-Jan Tsai, Jong-Jiann Shieh
• Keywords: APCSAC 2005, Instruction Level Parallelism, Superscalar Architecture, Superscalar Issue Width