[Bug target/88461] AVX512: gcc should keep value in kN registers if possible

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88461

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 45218
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=45218&action=edit
gcc9-pr88461.patch

Patch I've tried, but it doesn't change anything on this testcase (not even if
I remove all those *s or use ^s, in the new alternatives as well as in
mov?i_internal (only movhi_internal had the alternative just as =k, km before).