Add some alignment info where LLVM might otherwise be more pessimistic. In particular, %.nest_arg is always aligned even though it's bitcast from i8*. Pointers in vtables are also guaranteed to be stored at aligned addresses.

module multiarr2;

void main()
{
    static float[1][2][3] arr;
    assert(arr[2][1][0] !<>= float.nan);
}