HINTS implemented?

Created by: yaronbe1

We got an illegal instruction exception for the following command: c.add zero,a2

as far as I understand, the riscv spec states that c.add with zero as destination should be treated as a HINT. From riscv spec page 106: C.ADD adds the values in registers rd and rs2 and writes the result to register rd. C.ADD expandsinto add rd, rd, rs2. C.ADD is only valid when rs2̸=x0; the code points with rs2=x0 correspondto the C.JALR and C.EBREAK instructions. The code points with rs2̸=x0 and rd=x0 are HINTs.

According to the riscv spec a HINT should be treated by the core as a NOP and not as an illegal instruction.

As I mentioned above the ri5cy core gave an illegal instruction exception on this command.

HINTs not implemented in the ri5cy?