The gcc port is mature and has been upstreamed. The LLVM port is still a work-in-progress. I know there's been at least one talk presenting some thesis work on

The gcc port is mature and has been upstreamed. The LLVM port is still a work-in-progress. I know there's been at least one talk presenting some thesis work on an clock-less RISC-V design at an early RISC-V workshop, but I'm not aware of any in-progress implementations.