Automatic On-chip Memory Minimization for Data Reuse

FPGA-based computing engines have become a promising option for the implementation of computationally intensive applications due to high flexibility and parallelism. However, one of the main obstacles to overcome when trying to accelerate an application on an FPGA is the bottleneck in off-chip communication, typically to large memories. Often it is known at compile-time that the same data item is accessed many times, and as a result can be loaded once from large off-chip RAM onto scarce on-chip RAM, alleviating this bottleneck. This paper addresses how to automatically derive an address mapping that reduces the size of the required on-chip memory for a given memory access pattern. Experimental results demonstrate that, in practice, our approach reduces on-chip storage requirements to the minimum, corresponding to a reduction in on-chip memory size of up to 40× (average 10×) for some benchmarks compared to a naive approach. At the same time, no clock period penalty or increase in control logic area compared to this approach is observed for these benchmarks.