CLARINET: A RISC-V Based Framework for Posit Arithmetic Empiricism

Many engineering and scientific applications require high precision arithmetic. IEEE~754-2008 compliant (floating-point) arithmetic is the de facto standard for performing these computations. Recently, posit arithmetic has been proposed as a drop-in replacement for floating-point arithmetic. The posit data representation and arithmetic offer several absolute advantages over the floating-point format and arithmetic including higher dynamic range, better accuracy, and superior performance-area trade-offs. In this paper, we present a consolidated general-purpose processor-based framework to support posit arithmetic empiricism. The end-users of the framework have the liberty to seamlessly experiment with their applications using posit and floating-point arithmetic since the framework is designed for the two number systems to coexist. The framework consists of Melodica and Clarinet. Melodica is a posit arithmetic core that implements parametric fused-multiply-accumulate and, more importantly, supports the quire data type. Clarinet is a Melodica-enabled processor based on the RISC-V ISA. To the best of our knowledge, this is the first-ever integration of quire to a RISC-V core. To show the effectiveness of the Clarinet platform, we perform an extensive application study and benchmarking on some of the common linear algebra and computer vision kernels. We perform ASIC synthesis of Clarinet and Melodica on a 90~nm-CMOS Faraday process. Finally, based on our analysis and synthesis results, we define a quality metric for the different instances of Clarinet that gives us initial recommendations on the goodness of the instances. Clarinet-Melodica is an easy-to-experiment platform that will be made available in open-source for posit arithmetic empiricism.