[Bug tree-optimization/84824] DCE fails to remove dead code of std::function constructor

[manjian2006 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84824

--- Comment #13 from linzj <manjian2006 at gmail dot com> ---
But the code looks like only using the clobber set of the call statment. I will
look into that.