AFAICT the RISCV spec states the rotate/shift amounts are always amt & 31 modulo so there are no out of bound amounts that can create poison.

We already say ISD::ROTL/ROTR can't create undef/poison for the same reason, so RISCISD::ROLW/RORW should be OK, but its whether everyone is happy to handle SLLW/SRAW/SRLW similarly.