Evaluation Of Approximate Operators Case Study: Sobel Filter Application Executed On An Approximate Risc-V Platform

Approximate computing techniques have been proposed to decrease the energy consumption or improve the performance of computation. Several designs of approximate arithmetic operators are proposed in the literature, suggesting that the operators' energy can be reduced up to 46%. This paper puts existing work in perspective by studying the impact of these operators in a processor targeting the embedded systems. We augment a RISC-V processor with approximate addition and multiplication that support a variable bit-width in the range of 1 to 16 bits. We investigate the error-energy trade-off for a Sobel filter application. The results indicate that, for an acceptable output image degradation, 7.5% of the energy is saved. We conclude that the benefits of using approximate operators in embedded systems processors, have yet to be proved.