[Bug target/120297] [15/16 Regression] RISC-V: Miscompile at -O3

[rdapp at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120297

--- Comment #7 from Robin Dapp <rdapp at gcc dot gnu.org> ---
Picking a random commit in May (r16-649-g5c012971969db9) also shows the issue.

It looks as if we pick the wrong LMUL for a store and this rule is to blame:

DEF_SEW_LMUL_RULE (
  ratio_and_ge_sew, sew_only, sew_only,
  sew_le_and_next_sew_le_prev_max_sew_and_prev_ratio_valid_for_next_sew_p,
  always_false, use_next_sew_with_prev_ratio)

Looking into it.