[Bug tree-optimization/88775] [8/9 Regression] Optimize std::string assignment

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88775

--- Comment #14 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Of course only for equality comparisons, for non-equality the code is ok as is.