High-Level Synthesis Design Space Exploration: Past, Present, and Future

This article presents a survey of the different modern high-level synthesis (HLS) design space exploration (DSE) techniques that have been proposed so far to automatically generate hardware accelerators of different tradeoffs. HLS has multiple advantages compared to traditional RT-level-based hardware design. One key advantage is that a variety of different microarchitectures of unique tradeoffs can be obtained from the same untimed behavioral description by setting different synthesis options. Out of all the possible microarchitectures, the one that the designers are most interested in are the Pareto-optimal ones. The main problem is that the search space grows superlinearly with the number of synthesis options, and hence, heuristics have been proposed to search the space efficiently. This article summarizes the main techniques proposed and addresses the critical issues still not resolved as well identifies new opportunities in this field. It also serves as a guide for anyone wanting to create their own HLS DSE.