[Bug rtl-optimization/65078] [5 Regression] 4.9 and 5.0 generate more spill-fill in comparison with 4.8.2

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65078

--- Comment #11 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 35044
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35044&action=edit
gcc5-pr65078.patch

Untested fix using a pre-reload splitter of mov[sd]i if the source is SI/DImode
lowpart subreg of 16/32/64 byte vector register.