Efficient management of custom instructions for run-time reconfigurable instruction set processors

The instruction set extension capability of RISPs (reconfigurable instruction set processors) provides an attractive means to meet the flexibility, performance, and cost demands of ubiquitous computing devices. Run-time reconfiguration can further increase the cost efficiency and hardware specialization of these processors by dynamically changing the configuration of the reconfigurable logic to the required functionality. In this paper, we propose the use of a heuristic that leads to the selection of large custom instructions for increased performance gain. Result analysis of six applications from the MiBench embedded benchmark suite show that efficient data-path merging can be applied to the custom instructions to reduce the average number of configurations to less than 8 in a run-time RISP. In addition, there is only a small difference in the average number of configurations when compared to a custom instruction selection strategy that results in lower performance