[Bug target/70421] [5/6 Regression] wrong code with v16si vector and useless cast at -O -mavx512f

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70421

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 38114
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=38114&action=edit
gcc6-pr70421.patch

Full patch I'm going to bootstrap/regtest.