struct basic {
    std::string protocol;
    std::string username;
    std::string password;
    std::string hostname;
    std::string port;
    std::string pathname;
    std::string search;
    std::string hash;
};

enum class component {
     PROTOCOL = 0,
     USERNAME = 1,
     PASSWORD = 2,
     HOSTNAME = 3,
     PORT = 4,
     PATHNAME  = 5,
     SEARCH = 6,
     HASH = 7,
};

std::string& get_component(basic& url, component comp) {
    switch (comp) {
        case component::PROTOCOL: return url.protocol;
        case component::USERNAME: return url.username;
        case component::PASSWORD: return url.password;
        case component::HOSTNAME: return url.hostname;
        case component::PORT:     return url.port;
        case component::PATHNAME: return url.pathname;
        case component::SEARCH:   return url.search;
        case component::HASH:     return url.hash;
    }
}

struct fat {
    std::array<std::string, 7> data;
    std::string &protocol = data[0];
    std::string &username = data[1];
    std::string &password = data[2];
    std::string &hostname  = data[3];
    std::string &port  = data[4];
    std::string &pathname = data[5];
    std::string &search = data[6];
    std::string &hash = data[7];
};

std::string& get_component(fat& url, component comp) {
    return url.data[int(comp)];
};

struct advanced {
    std::array<std::string, 7> data;
    std::string &protocol() { return data[0]; }
    std::string &username() { return data[1]; }
    std::string &password() { return data[2]; }
    std::string &hostname() { return data[3]; }
    std::string &port() { return data[4]; }
    std::string &pathname() { return data[5]; }
    std::string &search() { return data[6]; }
    std::string &hash() { return data[7]; }
};

reports regressions in various spec benchmarks, with
up to 600% slowdown of the cactusBSSN benchmark on some platforms. The
benchmark seems to create many mappings of 4632kB, which would have merged
to a large THP-backed area before commit efa7df3e3bb5 and now they are
fragmented to multiple areas each aligned to PMD boundary with gaps
between. The regression then seems to be caused mainly due to the
benchmark's memory access pattern suffering from TLB or cache aliasing due
to the aligned boundaries of the individual areas