[Bug c++/82505] g++ -O3 -funroll-loops generates weird code

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82505

--- Comment #2 from Marc Glisse <glisse at gcc dot gnu.org> ---
dest/src might alias anything (even themselves), so the compiler can't really
optimize much.