RVfplib: A Fast and Compact Open-Source Floating-Point Emulation Library for Tiny RISC-V Processors

Abstract

Small, low-cost IoT devices rely on floating-point (FP) software emulation on 32-bit integer cores when the cost of a full-fledged FPU is not affordable. Thus, the performance and code size of the FP emulation library are decisive for meeting energy and memory-size constraints. We propose RVfplib, the first ISA-optimized open-source library for single and double-precision IEEE 754 FP emulation on RV32IM[C] cores. RVfplib is 59% smaller and 2x faster than the GCC emulation library, on average. On benchmark programs, code size reduction is 39%, and performance boost 1.5x. RVfplib is 5.3% smaller than the leading closed-source RISC-V commercial library.