[Bug tree-optimization/84339] [8 Regression] Wrong-code with optimizing strlen

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84339

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 43396
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=43396&action=edit
gcc8-pr84339.patch

Untested fix.