pub fn memcpy_ty<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
    bx: &mut Bx,
    dst: Bx::Value,
    dst_align: Align,
    src: Bx::Value,
    src_align: Align,
    layout: TyAndLayout<'tcx>,
    flags: MemFlags
)