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diff --git a/source/blender/depsgraph/util/depsgraph_util_transitive.cc b/source/blender/depsgraph/util/depsgraph_util_transitive.cc
new file mode 100644
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+++ b/source/blender/depsgraph/util/depsgraph_util_transitive.cc
@@ -0,0 +1,139 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2015 Blender Foundation.
+ * All rights reserved.
+ *
+ * Contributor(s): Lukas Toenne,
+ *                 Sergey Sharybin,
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/depsgraph/util/depsgraph_util_transitive.cc
+ *  \ingroup depsgraph
+ */
+
+extern "C" {
+#include "MEM_guardedalloc.h"
+
+#include "BLI_utildefines.h"
+
+#include "DNA_ID.h"
+
+#include "RNA_access.h"
+#include "RNA_types.h"
+}
+
+#include "depsgraph_util_transitive.h"
+#include "depsgraph.h"
+#include "depsnode.h"
+#include "depsnode_component.h"
+#include "depsnode_operation.h"
+
+/* -------------------------------------------------- */
+
+/* Performs a transitive reduction to remove redundant relations.
+ * http://en.wikipedia.org/wiki/Transitive_reduction
+ *
+ * XXX The current implementation is somewhat naive and has O(V*E) worst case
+ * runtime.
+ * A more optimized algorithm can be implemented later, e.g.
+ *
+ *   http://www.sciencedirect.com/science/article/pii/0304397588900321/pdf?md5=3391e309b708b6f9cdedcd08f84f4afc&pid=1-s2.0-0304397588900321-main.pdf
+ *
+ * Care has to be taken to make sure the algorithm can handle the cyclic case
+ * too! (unless we can to prevent this case early on).
+ */
+
+enum {
+	OP_VISITED = 1,
+	OP_REACHABLE = 2,
+};
+
+static void deg_graph_tag_paths_recursive(DepsNode *node)
+{
+	if (node->done & OP_VISITED)
+		return;
+	node->done |= OP_VISITED;
+
+	for (OperationDepsNode::Relations::const_iterator it = node->inlinks.begin();
+	     it != node->inlinks.end();
+	     ++it)
+	{
+		DepsRelation *rel = *it;
+
+		deg_graph_tag_paths_recursive(rel->from);
+		/* Do this only in inlinks loop, so the target node does not get
+		 * flagged.
+		 */
+		rel->from->done |= OP_REACHABLE;
+	}
+}
+
+void deg_graph_transitive_reduction(Depsgraph *graph)
+{
+	for (Depsgraph::OperationNodes::const_iterator it_target = graph->operations.begin();
+	     it_target != graph->operations.end();
+	     ++it_target)
+	{
+		OperationDepsNode *target = *it_target;
+
+		/* Clear tags. */
+		for (Depsgraph::OperationNodes::const_iterator it = graph->operations.begin();
+		     it != graph->operations.end();
+		     ++it)
+		{
+			OperationDepsNode *node = *it;
+			node->done = 0;
+		}
+
+		/* mark nodes from which we can reach the target
+		 * start with children, so the target node and direct children are not
+		 * flagged.
+		 */
+		target->done |= OP_VISITED;
+		for (OperationDepsNode::Relations::const_iterator it = target->inlinks.begin();
+		     it != target->inlinks.end();
+		     ++it)
+		{
+			DepsRelation *rel = *it;
+
+			deg_graph_tag_paths_recursive(rel->from);
+		}
+
+		/* Eemove redundant paths to the target. */
+		for (DepsNode::Relations::const_iterator it_rel = target->inlinks.begin();
+		     it_rel != target->inlinks.end();
+		     )
+		{
+			DepsRelation *rel = *it_rel;
+			/* Increment in advance, so we can safely remove the relation. */
+			++it_rel;
+
+			if (rel->from->type == DEPSNODE_TYPE_TIMESOURCE) {
+				/* HACK: time source nodes don't get "done" flag set/cleared. */
+				/* TODO: there will be other types in future, so iterators above
+				 * need modifying.
+				 */
+			}
+			else if (rel->from->done & OP_REACHABLE) {
+				OBJECT_GUARDED_DELETE(rel, DepsRelation);
+			}
+		}
+	}
+}