Longnail: High-Level Synthesis of Portable Custom Instruction Set Extensions for RISC-V Processors from Descriptions in the Open-Source CoreDSL Language

In the RISC-V ecosystem, custom instruction set architecture extensions (ISAX) are an energy-efficient and cost-effective way to accelerate modern embedded workloads. However, exploring different combinations of base cores and ISAXes for a specific application requires automation and a level of portability across microarchitectures that is not provided by existing approaches.