DUK_LOCAL void duk__mark_hobject(duk_heap *heap, duk_hobject *h) {
	duk_uint_fast32_t i;

	DUK_DDD(DUK_DDDPRINT("duk__mark_hobject: %p", (void *) h));

	DUK_ASSERT(h);

	/* XXX: use advancing pointers instead of index macros -> faster and smaller? */

	for (i = 0; i < (duk_uint_fast32_t) DUK_HOBJECT_GET_ENEXT(h); i++) {
		duk_hstring *key = DUK_HOBJECT_E_GET_KEY(heap, h, i);
		if (!key) {
			continue;
		}
		duk__mark_heaphdr(heap, (duk_heaphdr *) key);
		if (DUK_HOBJECT_E_SLOT_IS_ACCESSOR(heap, h, i)) {
			duk__mark_heaphdr(heap, (duk_heaphdr *) DUK_HOBJECT_E_GET_VALUE_PTR(heap, h, i)->a.get);
			duk__mark_heaphdr(heap, (duk_heaphdr *) DUK_HOBJECT_E_GET_VALUE_PTR(heap, h, i)->a.set);
		} else {
			duk__mark_tval(heap, &DUK_HOBJECT_E_GET_VALUE_PTR(heap, h, i)->v);
		}
	}

	for (i = 0; i < (duk_uint_fast32_t) DUK_HOBJECT_GET_ASIZE(h); i++) {
		duk__mark_tval(heap, DUK_HOBJECT_A_GET_VALUE_PTR(heap, h, i));
	}

	/* hash part is a 'weak reference' and does not contribute */

	duk__mark_heaphdr(heap, (duk_heaphdr *) DUK_HOBJECT_GET_PROTOTYPE(heap, h));

	if (DUK_HOBJECT_IS_COMPILEDFUNCTION(h)) {
		duk_hcompiledfunction *f = (duk_hcompiledfunction *) h;
		duk_tval *tv, *tv_end;
		duk_hobject **fn, **fn_end;

		/* 'data' is reachable through every compiled function which
		 * contains a reference.
		 */

		duk__mark_heaphdr(heap, (duk_heaphdr *) DUK_HCOMPILEDFUNCTION_GET_DATA(heap, f));

		tv = DUK_HCOMPILEDFUNCTION_GET_CONSTS_BASE(heap, f);
		tv_end = DUK_HCOMPILEDFUNCTION_GET_CONSTS_END(heap, f);
		while (tv < tv_end) {
			duk__mark_tval(heap, tv);
			tv++;
		}

		fn = DUK_HCOMPILEDFUNCTION_GET_FUNCS_BASE(heap, f);
		fn_end = DUK_HCOMPILEDFUNCTION_GET_FUNCS_END(heap, f);
		while (fn < fn_end) {
			duk__mark_heaphdr(heap, (duk_heaphdr *) *fn);
			fn++;
		}
	} else if (DUK_HOBJECT_IS_NATIVEFUNCTION(h)) {
		duk_hnativefunction *f = (duk_hnativefunction *) h;
		DUK_UNREF(f);
		/* nothing to mark */
	} else if (DUK_HOBJECT_IS_BUFFEROBJECT(h)) {
		duk_hbufferobject *b = (duk_hbufferobject *) h;
		duk__mark_heaphdr(heap, (duk_heaphdr *) b->buf);
	} else if (DUK_HOBJECT_IS_THREAD(h)) {
		duk_hthread *t = (duk_hthread *) h;
		duk_tval *tv;

		tv = t->valstack;
		while (tv < t->valstack_top) {
			duk__mark_tval(heap, tv);
			tv++;
		}

		for (i = 0; i < (duk_uint_fast32_t) t->callstack_top; i++) {
			duk_activation *act = t->callstack + i;
			duk__mark_heaphdr(heap, (duk_heaphdr *) DUK_ACT_GET_FUNC(act));
			duk__mark_heaphdr(heap, (duk_heaphdr *) act->var_env);
			duk__mark_heaphdr(heap, (duk_heaphdr *) act->lex_env);
#ifdef DUK_USE_NONSTD_FUNC_CALLER_PROPERTY
			duk__mark_heaphdr(heap, (duk_heaphdr *) act->prev_caller);
#endif
		}

#if 0  /* nothing now */
		for (i = 0; i < (duk_uint_fast32_t) t->catchstack_top; i++) {
			duk_catcher *cat = t->catchstack + i;
		}
#endif

		duk__mark_heaphdr(heap, (duk_heaphdr *) t->resumer);

		/* XXX: duk_small_uint_t would be enough for this loop */
		for (i = 0; i < DUK_NUM_BUILTINS; i++) {
			duk__mark_heaphdr(heap, (duk_heaphdr *) t->builtins[i]);
		}
	}
}
/* Raw helper to extract internal information / statistics about a value.
 * The return values are version specific and must not expose anything
 * that would lead to security issues (e.g. exposing compiled function
 * 'data' buffer might be an issue).  Currently only counts and sizes and
 * such are given so there should not be a security impact.
 */
DUK_INTERNAL duk_ret_t duk_bi_duktape_object_info(duk_context *ctx) {
	duk_hthread *thr = (duk_hthread *) ctx;
	duk_tval *tv;
	duk_heaphdr *h;
	duk_int_t i, n;

	DUK_UNREF(thr);

	/* result array */
	duk_push_array(ctx);  /* -> [ val arr ] */

	/* type tag (public) */
	duk_push_int(ctx, duk_get_type(ctx, 0));

	/* address */
	tv = duk_get_tval(ctx, 0);
	DUK_ASSERT(tv != NULL);  /* because arg count is 1 */
	if (DUK_TVAL_IS_HEAP_ALLOCATED(tv)) {
		h = DUK_TVAL_GET_HEAPHDR(tv);
		duk_push_pointer(ctx, (void *) h);
	} else {
		/* internal type tag */
		duk_push_int(ctx, (duk_int_t) DUK_TVAL_GET_TAG(tv));
		goto done;
	}
	DUK_ASSERT(h != NULL);

	/* refcount */
#ifdef DUK_USE_REFERENCE_COUNTING
	duk_push_size_t(ctx, DUK_HEAPHDR_GET_REFCOUNT(h));
#else
	duk_push_undefined(ctx);
#endif

	/* heaphdr size and additional allocation size, followed by
	 * type specific stuff (with varying value count)
	 */
	switch ((duk_small_int_t) DUK_HEAPHDR_GET_TYPE(h)) {
	case DUK_HTYPE_STRING: {
		duk_hstring *h_str = (duk_hstring *) h;
		duk_push_uint(ctx, (duk_uint_t) (sizeof(duk_hstring) + DUK_HSTRING_GET_BYTELEN(h_str) + 1));
		break;
	}
	case DUK_HTYPE_OBJECT: {
		duk_hobject *h_obj = (duk_hobject *) h;
		duk_small_uint_t hdr_size;
		if (DUK_HOBJECT_IS_COMPILEDFUNCTION(h_obj)) {
			hdr_size = (duk_small_uint_t) sizeof(duk_hcompiledfunction);
		} else if (DUK_HOBJECT_IS_NATIVEFUNCTION(h_obj)) {
			hdr_size = (duk_small_uint_t) sizeof(duk_hnativefunction);
		} else if (DUK_HOBJECT_IS_THREAD(h_obj)) {
			hdr_size = (duk_small_uint_t) sizeof(duk_hthread);
#if defined(DUK_USE_BUFFEROBJECT_SUPPORT)
		} else if (DUK_HOBJECT_IS_BUFFEROBJECT(h_obj)) {
			hdr_size = (duk_small_uint_t) sizeof(duk_hbufferobject);
#endif
		} else {
			hdr_size = (duk_small_uint_t) sizeof(duk_hobject);
		}
		duk_push_uint(ctx, (duk_uint_t) hdr_size);
		duk_push_uint(ctx, (duk_uint_t) DUK_HOBJECT_P_ALLOC_SIZE(h_obj));
		duk_push_uint(ctx, (duk_uint_t) DUK_HOBJECT_GET_ESIZE(h_obj));
		/* Note: e_next indicates the number of gc-reachable entries
		 * in the entry part, and also indicates the index where the
		 * next new property would be inserted.  It does *not* indicate
		 * the number of non-NULL keys present in the object.  That
		 * value could be counted separately but requires a pass through
		 * the key list.
		 */
		duk_push_uint(ctx, (duk_uint_t) DUK_HOBJECT_GET_ENEXT(h_obj));
		duk_push_uint(ctx, (duk_uint_t) DUK_HOBJECT_GET_ASIZE(h_obj));
		duk_push_uint(ctx, (duk_uint_t) DUK_HOBJECT_GET_HSIZE(h_obj));
		if (DUK_HOBJECT_IS_COMPILEDFUNCTION(h_obj)) {
			duk_hbuffer *h_data = (duk_hbuffer *) DUK_HCOMPILEDFUNCTION_GET_DATA(thr->heap, (duk_hcompiledfunction *) h_obj);
			if (h_data) {
				duk_push_uint(ctx, (duk_uint_t) DUK_HBUFFER_GET_SIZE(h_data));
			} else {
				duk_push_uint(ctx, 0);
			}
		}
		break;
	}
	case DUK_HTYPE_BUFFER: {
		duk_hbuffer *h_buf = (duk_hbuffer *) h;
		if (DUK_HBUFFER_HAS_DYNAMIC(h_buf)) {
			if (DUK_HBUFFER_HAS_EXTERNAL(h_buf)) {
				duk_push_uint(ctx, (duk_uint_t) (sizeof(duk_hbuffer_external)));
			} else {
				/* When alloc_size == 0 the second allocation may not
				 * actually exist.
				 */
				duk_push_uint(ctx, (duk_uint_t) (sizeof(duk_hbuffer_dynamic)));
			}
			duk_push_uint(ctx, (duk_uint_t) (DUK_HBUFFER_GET_SIZE(h_buf)));
		} else {
			duk_push_uint(ctx, (duk_uint_t) (sizeof(duk_hbuffer_fixed) + DUK_HBUFFER_GET_SIZE(h_buf) + 1));
		}
		break;

	}
	}

 done:
	/* set values into ret array */
	/* XXX: primitive to make array from valstack slice */
	n = duk_get_top(ctx);
	for (i = 2; i < n; i++) {
		duk_dup(ctx, i);
		duk_put_prop_index(ctx, 1, i - 2);
	}
	duk_dup(ctx, 1);
	return 1;
}
DUK_LOCAL void duk__refcount_finalize_hobject(duk_hthread *thr, duk_hobject *h) {
	duk_uint_fast32_t i;

	DUK_ASSERT(h);
	DUK_ASSERT(DUK_HEAPHDR_GET_TYPE((duk_heaphdr *) h) == DUK_HTYPE_OBJECT);

	/* XXX: better to get base and walk forwards? */

	for (i = 0; i < (duk_uint_fast32_t) DUK_HOBJECT_GET_ENEXT(h); i++) {
		duk_hstring *key = DUK_HOBJECT_E_GET_KEY(thr->heap, h, i);
		if (!key) {
			continue;
		}
		duk_heaphdr_decref(thr, (duk_heaphdr *) key);
		if (DUK_HOBJECT_E_SLOT_IS_ACCESSOR(thr->heap, h, i)) {
			duk_heaphdr_decref_allownull(thr, (duk_heaphdr *) DUK_HOBJECT_E_GET_VALUE_GETTER(thr->heap, h, i));
			duk_heaphdr_decref_allownull(thr, (duk_heaphdr *) DUK_HOBJECT_E_GET_VALUE_SETTER(thr->heap, h, i));
		} else {
			duk_tval_decref(thr, DUK_HOBJECT_E_GET_VALUE_TVAL_PTR(thr->heap, h, i));
		}
	}

	for (i = 0; i < (duk_uint_fast32_t) DUK_HOBJECT_GET_ASIZE(h); i++) {
		duk_tval_decref(thr, DUK_HOBJECT_A_GET_VALUE_PTR(thr->heap, h, i));
	}

	/* hash part is a 'weak reference' and does not contribute */

	duk_heaphdr_decref_allownull(thr, (duk_heaphdr *) DUK_HOBJECT_GET_PROTOTYPE(thr->heap, h));

	if (DUK_HOBJECT_IS_COMPILEDFUNCTION(h)) {
		duk_hcompiledfunction *f = (duk_hcompiledfunction *) h;
		duk_tval *tv, *tv_end;
		duk_hobject **funcs, **funcs_end;

		DUK_ASSERT(DUK_HCOMPILEDFUNCTION_GET_DATA(thr->heap, f) != NULL);  /* compiled functions must be created 'atomically' */

		tv = DUK_HCOMPILEDFUNCTION_GET_CONSTS_BASE(thr->heap, f);
		tv_end = DUK_HCOMPILEDFUNCTION_GET_CONSTS_END(thr->heap, f);
		while (tv < tv_end) {
			duk_tval_decref(thr, tv);
			tv++;
		}

		funcs = DUK_HCOMPILEDFUNCTION_GET_FUNCS_BASE(thr->heap, f);
		funcs_end = DUK_HCOMPILEDFUNCTION_GET_FUNCS_END(thr->heap, f);
		while (funcs < funcs_end) {
			duk_heaphdr_decref(thr, (duk_heaphdr *) *funcs);
			funcs++;
		}

		duk_heaphdr_decref(thr, (duk_heaphdr *) DUK_HCOMPILEDFUNCTION_GET_DATA(thr->heap, f));
	} else if (DUK_HOBJECT_IS_NATIVEFUNCTION(h)) {
		duk_hnativefunction *f = (duk_hnativefunction *) h;
		DUK_UNREF(f);
		/* nothing to finalize */
	} else if (DUK_HOBJECT_IS_BUFFEROBJECT(h)) {
		duk_hbufferobject *b = (duk_hbufferobject *) h;
		if (b->buf) {
			duk_heaphdr_decref(thr, (duk_heaphdr *) b->buf);
		}
	} else if (DUK_HOBJECT_IS_THREAD(h)) {
		duk_hthread *t = (duk_hthread *) h;
		duk_tval *tv;

		tv = t->valstack;
		while (tv < t->valstack_top) {
			duk_tval_decref(thr, tv);
			tv++;
		}

		for (i = 0; i < (duk_uint_fast32_t) t->callstack_top; i++) {
			duk_activation *act = t->callstack + i;
			duk_heaphdr_decref_allownull(thr, (duk_heaphdr *) DUK_ACT_GET_FUNC(act));
			duk_heaphdr_decref_allownull(thr, (duk_heaphdr *) act->var_env);
			duk_heaphdr_decref_allownull(thr, (duk_heaphdr *) act->lex_env);
#ifdef DUK_USE_NONSTD_FUNC_CALLER_PROPERTY
			duk_heaphdr_decref_allownull(thr, (duk_heaphdr *) act->prev_caller);
#endif
		}

#if 0  /* nothing now */
		for (i = 0; i < (duk_uint_fast32_t) t->catchstack_top; i++) {
			duk_catcher *cat = t->catchstack + i;
		}
#endif

		for (i = 0; i < DUK_NUM_BUILTINS; i++) {
			duk_heaphdr_decref_allownull(thr, (duk_heaphdr *) t->builtins[i]);
		}

		duk_heaphdr_decref_allownull(thr, (duk_heaphdr *) t->resumer);
	}
}