[Bug tree-optimization/20999] store should not be done if we don't change its value

[law at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=20999

--- Comment #2 from Jeffrey A. Law <law at gcc dot gnu.org> ---
We should keep in mind that taking a branch mispredict can be critically
important and potentially more important than avoiding the redundant store.