DUK_LOCAL void duk__compact_object_list(duk_heap *heap, duk_hthread *thr, duk_heaphdr *start, duk_size_t *p_count_check, duk_size_t *p_count_compact, duk_size_t *p_count_bytes_saved) {
#else
DUK_LOCAL void duk__compact_object_list(duk_heap *heap, duk_hthread *thr, duk_heaphdr *start) {
#endif
	duk_heaphdr *curr;
#if defined(DUK_USE_DEBUG)
	duk_size_t old_size, new_size;
#endif
	duk_hobject *obj;

	DUK_UNREF(heap);

	curr = start;
	while (curr) {
		DUK_DDD(DUK_DDDPRINT("mark-and-sweep compact: %p", (void *) curr));

		if (DUK_HEAPHDR_GET_TYPE(curr) != DUK_HTYPE_OBJECT) {
			goto next;
		}
		obj = (duk_hobject *) curr;

#if defined(DUK_USE_DEBUG)
		old_size = DUK_HOBJECT_P_COMPUTE_SIZE(DUK_HOBJECT_GET_ESIZE(obj),
		                                      DUK_HOBJECT_GET_ASIZE(obj),
		                                      DUK_HOBJECT_GET_HSIZE(obj));
#endif

		DUK_DD(DUK_DDPRINT("compact object: %p", (void *) obj));
		duk_push_hobject((duk_context *) thr, obj);
		/* XXX: disable error handlers for duration of compaction? */
		duk_safe_call((duk_context *) thr, duk__protected_compact_object, NULL, 1, 0);

#if defined(DUK_USE_DEBUG)
		new_size = DUK_HOBJECT_P_COMPUTE_SIZE(DUK_HOBJECT_GET_ESIZE(obj),
		                                      DUK_HOBJECT_GET_ASIZE(obj),
		                                      DUK_HOBJECT_GET_HSIZE(obj));
#endif

#if defined(DUK_USE_DEBUG)
		(*p_count_compact)++;
		(*p_count_bytes_saved) += (duk_size_t) (old_size - new_size);
#endif

	 next:
		curr = DUK_HEAPHDR_GET_NEXT(heap, curr);
#if defined(DUK_USE_DEBUG)
		(*p_count_check)++;
#endif
	}
}
DUK_LOCAL void duk__duplicate_ram_global_object(duk_hthread *thr) {
	duk_context *ctx;
	duk_hobject *h1;
#if defined(DUK_USE_ROM_GLOBAL_CLONE)
	duk_hobject *h2;
	duk_uint8_t *props;
	duk_size_t alloc_size;
#endif

	ctx = (duk_context *) thr;

	/* XXX: refactor into internal helper, duk_clone_hobject() */

#if defined(DUK_USE_ROM_GLOBAL_INHERIT)
	/* Inherit from ROM-based global object: less RAM usage, less transparent. */
	duk_push_object_helper(ctx,
	                       DUK_HOBJECT_FLAG_EXTENSIBLE |
	                       DUK_HOBJECT_CLASS_AS_FLAGS(DUK_HOBJECT_CLASS_GLOBAL),
	                       DUK_BIDX_GLOBAL);
	h1 = duk_get_hobject(ctx, -1);
	DUK_ASSERT(h1 != NULL);
#elif defined(DUK_USE_ROM_GLOBAL_CLONE)
	/* Clone the properties of the ROM-based global object to create a
	 * fully RAM-based global object.  Uses more memory than the inherit
	 * model but more compliant.
	 */
	duk_push_object_helper(ctx,
	                       DUK_HOBJECT_FLAG_EXTENSIBLE |
	                       DUK_HOBJECT_CLASS_AS_FLAGS(DUK_HOBJECT_CLASS_GLOBAL),
	                       DUK_BIDX_OBJECT_PROTOTYPE);
	h1 = duk_get_hobject(ctx, -1);
	DUK_ASSERT(h1 != NULL);
	h2 = thr->builtins[DUK_BIDX_GLOBAL];
	DUK_ASSERT(h2 != NULL);

	/* Copy the property table verbatim; this handles attributes etc.
	 * For ROM objects it's not necessary (or possible) to update
	 * refcounts so leave them as is.
	 */
	alloc_size = DUK_HOBJECT_P_ALLOC_SIZE(h2);
	DUK_ASSERT(alloc_size > 0);
	props = DUK_ALLOC(thr->heap, alloc_size);
	if (!props) {
		DUK_ERROR_ALLOC_FAILED(thr);
		return;
	}
	DUK_ASSERT(DUK_HOBJECT_GET_PROPS(thr->heap, h2) != NULL);
	DUK_MEMCPY((void *) props, (const void *) DUK_HOBJECT_GET_PROPS(thr->heap, h2), alloc_size);

	/* XXX: keep property attributes or tweak them here?
	 * Properties will now be non-configurable even when they're
	 * normally configurable for the global object.
	 */

	DUK_ASSERT(DUK_HOBJECT_GET_PROPS(thr->heap, h1) == NULL);
	DUK_HOBJECT_SET_PROPS(thr->heap, h1, props);
	DUK_HOBJECT_SET_ESIZE(h1, DUK_HOBJECT_GET_ESIZE(h2));
	DUK_HOBJECT_SET_ENEXT(h1, DUK_HOBJECT_GET_ENEXT(h2));
	DUK_HOBJECT_SET_ASIZE(h1, DUK_HOBJECT_GET_ASIZE(h2));
	DUK_HOBJECT_SET_HSIZE(h1, DUK_HOBJECT_GET_HSIZE(h2));
#else
#error internal error in defines
#endif

	duk_hobject_compact_props(thr, h1);
	DUK_ASSERT(thr->builtins[DUK_BIDX_GLOBAL] != NULL);
	DUK_ASSERT(!DUK_HEAPHDR_NEEDS_REFCOUNT_UPDATE((duk_heaphdr *) thr->builtins[DUK_BIDX_GLOBAL]));  /* no need to decref */
	thr->builtins[DUK_BIDX_GLOBAL] = h1;
	DUK_HOBJECT_INCREF(thr, h1);
	DUK_D(DUK_DPRINT("duplicated global object: %!O", h1));


	/* Create a fresh object environment for the global scope.  This is
	 * needed so that the global scope points to the newly created RAM-based
	 * global object.
	 */
	duk_push_object_helper(ctx,
	                       DUK_HOBJECT_FLAG_EXTENSIBLE |
	                       DUK_HOBJECT_CLASS_AS_FLAGS(DUK_HOBJECT_CLASS_OBJENV),
	                       -1);  /* no prototype */
	h1 = duk_get_hobject(ctx, -1);
	DUK_ASSERT(h1 != NULL);
	duk_dup(ctx, -2);
	duk_dup(ctx, -1);  /* -> [ ... new_global new_globalenv new_global new_global ] */
	duk_xdef_prop_stridx(thr, -3, DUK_STRIDX_INT_TARGET, DUK_PROPDESC_FLAGS_NONE);
	duk_xdef_prop_stridx(thr, -2, DUK_STRIDX_INT_THIS, DUK_PROPDESC_FLAGS_NONE);  /* always provideThis=true */

	duk_hobject_compact_props(thr, h1);
	DUK_ASSERT(thr->builtins[DUK_BIDX_GLOBAL_ENV] != NULL);
	DUK_ASSERT(!DUK_HEAPHDR_NEEDS_REFCOUNT_UPDATE((duk_heaphdr *) thr->builtins[DUK_BIDX_GLOBAL_ENV]));  /* no need to decref */
	thr->builtins[DUK_BIDX_GLOBAL_ENV] = h1;
	DUK_HOBJECT_INCREF(thr, h1);
	DUK_D(DUK_DPRINT("duplicated global env: %!O", h1));

	duk_pop_2(ctx);
}
/* 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;
}