[Bug target/92686] Inefficient mask operation for 128/256-bit vector VCOND_EXPR under avx512f

[crazylht at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92686

--- Comment #1 from Hongtao.liu <crazylht at gmail dot com> ---
My local patch shows there's no big performance impact on SPEC2017.