The previous design, RISC-IV (named SPUR), was a Lisp machine.

http://pages.cs.wisc.edu/~markhill/papers/computer86_spur.pd...

The basic instructions (Table 3) are close enough to RISC-V but it also had a few Lisp specific instructions (Table 4). Though the name J Extension for RISC-V might lead you to think it is only about Java or Javascript, the group working on it is also interested in making it as good as possible for Lisp.