[Bug middle-end/121970] struct copy still use zmm even specify -mmove-max=256

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121970

--- Comment #1 from Hongtao Liu <liuhongt at gcc dot gnu.org> ---
Although the option is x86 specific, but I think the issue is middle-end, it's
related how MOVE_MAX and STORE_MAX_PIECES is used.