[Bug tree-optimization/90356] Missed optimization for variables initialized to 0.0

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90356

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 46301
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=46301&action=edit
gcc10-pr90356.patch

Full untested patch.