[Bug target/88473] AVX512: constant folding on mask does not remove unnecessary instructions

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88473

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The rationale for doing it the way it currently is done:
https://gcc.gnu.org/ml/gcc-patches/2016-11/msg02612.html