LGTM (even though I still don't like the spec :D). We still have an implicit assumption in riscv-vsetvl.cc that might modify LMUL:
In prev_ratio_valid_for_next_sew_p and next_ratio_valid_for_prev_sew_p we check whether the ratio of two LMULs is <= 8. ISTR that with recent changes we only re-use an existing ratio and don't compute a new one but it might be worth a second look. A while ago we certainly did change LMUL even to values that weren't initially enabled.
-- Regards Robin
