[Bug tree-optimization/101821] Redundant xor eax eax

[llvm at rifkin dot dev via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101821

--- Comment #1 from Jeremy R. <llvm at rifkin dot dev> ---
This happens with __builtin_popcount as well, not just std::popcount. This
appears to have started in GCC 4.9.2. https://godbolt.org/z/4dGWvT5zr