From Pthreads to Multicore Hardware Systems in LegUp High-Level Synthesis for FPGAs

In the last decade, processor speeds have remained fairly stagnant, and to improve performance further, the industry started to increase the number of processor cores. The use of specialized hardware, such as field-programmable gate arrays (FPGAs), has also been on the rise. The traditional design methodology for FPGAs, however, requires hardware knowledge, which makes the platform inaccessible to software engineers. High-level synthesis (HLS) tools aim to resolve this issue by allowing software design methodologies to be used for FPGAs. However, HLS remains difficult to use for many software engineers, as there are tasks, such as system integration, which is still mostly a manual process. Consequently, creating a multicore hardware system on an FPGA is not feasible for most software engineers. To this end, we provide an HLS framework, which can automatically generate a multicore hardware system from software. We provide support for POSIX threads, which can be compiled to concurrently executing hardware cores that can be used in a processor-accelerator hybrid system, or in a hardware-only system without a processor. With this, we show that we can create multicore FPGA systems that can provide significant benefits in performance and energy-efficiency compared with hardware executing sequentially, and software executing on MIPS/ARM/x86 processors.