Compiled multithreaded data paths on FPGAs for dynamic workloads

Hardware supported multithreading can mask memory latency by switching the execution to ready threads, which is particularly effective on irregular applications. FPGAs provide an opportunity to have multithreaded data paths customized to each individual application. In this paper we describe the compiler generation of these hardware structures from a C subset targeting a Convey HC-2ex machine. We describe how this compilation approach differs from other C to HDL compilers. We use the compiler to generate a multithreaded sparse matrix vector multiplication kernel and compare its performance to existing FPGA, and highly optimized software implementations.