[Bug target/85832] [AVX512] possible shorter code when comparing with vector of zeros

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85832

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 44227
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44227&action=edit
gcc9-pr85832.patch

Untested fix.