[Bug c++/59739] missed optimization: attribute ((pure)) with aggregate returns

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59739

--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---

>From PR 108635 (via PR 45115), a C++20 testcase where we should be able to
optimize into one call of `operator<=>`:

    #include <compare>

    struct S
    {
        std::weak_ordering operator<=>(const S&) const __attribute__((const));
    };

    int compare3way(S& a, S& b)
    {
        return (a < b) ? -1 : (a > b) ? 1 : 0;
    }