Domain specific abstractions for the development of fast-by-construction dataflow codes on FPGAs

FPGAs are popular in many fields but yet to gain wide acceptance for accelerating HPC codes. A major cause is that whilst the growth of High Level Synthesis (HLS), enabling the use of C or C++, has increased accessibility, without wide-spread algorithmic changes these tools only provide correct-by-construction rather than fast-by-construction programming. The fundamental issue is that HLS presents a Von Neumann based execution model which is poorly suited to FPGAs, resulting in significant disconnect between HLS's language semantics and how experienced FPGA programmers structure dataflow algorithms to exploit hardware. We have developed the high-level language Lucent which builds on principles previously developed for programming general-purpose dataflow architectures. Using Lucent as a vehicle, in this paper we explore appropriate abstractions for developing application specific dataflow machines on reconfigurable architectures. The result is an approach enabling fast-by-construction programming for FPGAs, delivering competitive performance against hand optimised HLS codes whilst significantly enhancing programmer productivity.