use std::any::{Any, TypeId};
use std::mem;

use runtime::Imp;

extern {
    fn objc_msgSend();
    fn objc_msgSend_stret();

    fn objc_msgSendSuper();
    fn objc_msgSendSuper_stret();
}

pub fn msg_send_fn<R: Any>() -> Imp {
    // Double-word sized fundamental data types don't use stret,
    // but any composite type larger than 4 bytes does.
    // <http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042e/IHI0042E_aapcs.pdf>

    let type_id = TypeId::of::<R>();
    if mem::size_of::<R>() <= 4 ||
            type_id == TypeId::of::<i64>() ||
            type_id == TypeId::of::<u64>() ||
            type_id == TypeId::of::<f64>() {
        objc_msgSend
    } else {
        objc_msgSend_stret
    }
}

pub fn msg_send_super_fn<R: Any>() -> Imp {
    let type_id = TypeId::of::<R>();
    if mem::size_of::<R>() <= 4 ||
            type_id == TypeId::of::<i64>() ||
            type_id == TypeId::of::<u64>() ||
            type_id == TypeId::of::<f64>() {
        objc_msgSendSuper
    } else {
        objc_msgSendSuper_stret
    }
}