Hrm—that's another case of missing isel from gcc/clang (c.f. <https://pp.ipd.kit.edu/firm/selgen https://pp.ipd.kit.edu/firm/selgen>)—my implementation (<https:

Hrm—that's another case of missing isel from gcc/clang (c.f. <https://pp.ipd.kit.edu/firm/selgen https://pp.ipd.kit.edu/firm/selgen>)—my implementation (<https://github.com/moon-chilled/fancy-memcmp/blob/master/memcmp-sse2.S#L82-L86 https://github.com/moon-chilled/fancy-memcmp/blob/master/mem...>) does it in one less instruction. (An alternative is to skip the xors and do cmp/setcc/setcc/sub/movsx, which matches my approach on instruction count, but relies on good handling of partial renames, which is uarch-dependent. And I can never remember if anybody can eliminate movsx. Otoh it is non-destructive.)