[Bug tree-optimization/81588] [7/8 Regression] Wrong code at -O2

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81588

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 41860
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41860&action=edit
gcc8-pr81588.patch

Untested fix.