Overlapping memory operations with circuit evaluation in reconfigurable computing

Abstract

This paper considers the problem of compiling programs, written in a general high-level programming language, into hardware circuits executed by an FPGA (Field Programmable Gate Array) unit. In particular, we consider the problem of synthesizing nested loops that frequently access array elements stored in an external memory (outside the FPGA). We propose an aggressive compilation scheme, based on loop unrolling and code flattening techniques, where array references from/to the external memory are overlapped with uninterrupted hardware evaluation of the synthesized loop's circuit. We implemented a restricted programming language called DOL based on the proposed compilation scheme and our experimental results provide preliminary evidence that aggressive compilation can be used to compile large code segments into circuits, including overlapping of hardware operations and memory references.