SV **sp = (my_perl->Istack_sp);
    I32 ax = (*(my_perl->Imarkstack_ptr)--);
    register SV **mark = (my_perl->Istack_base) + ax++;
    I32 items = (I32) (sp - mark);
    I32 ix = ((XPVCV *) ((void *) ((cv)->sv_any)))->xcv_start_u.xcv_xsubany.any_i32;