Characterizing embedded applications for instruction-set extensible processors

Abstract

Extensible processors, which allow customization for an application domain by extending the core instruction set architecture, are becoming increasingly popular for embedded systems. However, existing techniques restrict the set of possible candidates for custom instructions by imposing a variety of constraints. As a result, the true extent of performance improvement achievable by extensible processors for embedded applications remains unknown. Moreover, it is unclear how the interplay among these restrictions impacts the performance potential. Our careful examination of this issue shows that significant speedup can only be obtained by relaxing some of the constraints to a reasonable extent. In particular, to the best of our knowledge, ours is the first work that studies the impact of relaxing control flow constraint by identifying instructions across basic blocks and indicates 5-148% relative speedup for different applications.