[Bug sanitizer/89869] -fsanitize=undefined miscompilation

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89869

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 46056
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=46056&action=edit
gcc9-pr89869.patch

Untested fix.