| Summary: | 碩士 === 國立交通大學 === 資訊科學與工程研究所 === 94 === Instruction set extension (ISE) is an effective way to meet the growing efficiency demands for both circuit and speed in many applications. ISE generation flow usually consists of ISE exploration and ISE selection phases. In ISE exploration, in order to achieve the highest speed-up ratio, most works deploy the fastest implementation option for each operation in application specific functional unit (ASFU) which executes instruction in ISEs. Nevertheless, the fastest implementation option may be not the best choice. Two considerations are important in selecting an implementation option for each operation in ASFU: (1) the execution time of an ASFU should meet pipestage timing constraint, i.e. fit to an integral number of original pipeline cycles; and (2) under (1), the ASFU should use the least silicon area. To conform to these considerations, we propose an ISE exploration algorithm which not only explores ISE candidates but also their implementation options to minimize the execution time meanwhile use less silicon area. Results with MiBench indicate that the approach achieves up to 35.28%, 15.92% and 22.41% (max., min. and avg.) of further reduction in extra silicon area usage and only has maximally 1.06% performance loss compared with the approach without the consideration of pipestage timing constraint for ASFU. Furthermore, simulation results also show that our approach is very close to optimal one, but takes much less computing time.
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