GC.add_stress_to_class

static VALUE
rb_gcdebug_add_stress_to_class(int argc, VALUE *argv, VALUE self)
{
    rb_objspace_t *objspace = rb_gc_get_objspace();

    if (!stress_to_class) {
        set_stress_to_class(rb_ident_hash_new_capa(argc));
    }

    for (int i = 0; i < argc; i++) {
        VALUE klass = argv[i];
        rb_hash_aset(stress_to_class, klass, Qtrue);
    }

    return self;
}