[Bug tree-optimization/79408] Missed VRP optimization of integer modulo

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79408

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 40687
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40687&action=edit
gcc7-pr79408.patch

Untested fix.