Added support for using a temporary to implement emulated ABI return from inline asm, could be easier to use, but I think this will do. It's so extremely target dependent in any case that doing a completely generic approach seems hard.

extern(C) int printf(char*, ...);

class A
{
    int i;
    void f()
    {
        printf("A.f\n");
    }
}

class B : A
{
    long l;
    void f()
    {
        printf("B.f\n");
    }
}

void main()
{
    A a = new B;
    a.f();
}