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 complex2;

void main()
{
    cdouble c = 3.0 + 0i;
    cdouble d = 2.0 + 0i;
    cdouble c1 = c + 3.0;
    cdouble c2 = c - 3.0i;
    cdouble c3 = c / 2.0;
}