Depsgraph: Make Copy-on-Write a command line option

Before it was a compile time option which was not very easy to use or test. Now
the project is getting more mature, so very soon we will be able to call for a
public tests of limited features.

The copy-on-write (which includes animation, modifiers) is enabled using
--enable-copy-on-write command line argument.

15 files changed, 158 insertions, 149 deletions

diff --git a/source/blender/blenkernel/CMakeLists.txt b/source/blender/blenkernel/CMakeLists.txt
index dad862b87e7..b2883735343 100644
--- a/source/blender/blenkernel/CMakeLists.txt
+++ b/source/blender/blenkernel/CMakeLists.txt
@@ -541,8 +541,4 @@ endif()
 #	set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /WX")
 #endif()
 
-if(WITH_DEPSGRAPH_COPY_ON_WRITE)
-	add_definitions(-DWITH_COPY_ON_WRITE)
-endif()
-
 blender_add_lib(bf_blenkernel "${SRC}" "${INC}" "${INC_SYS}")
diff --git a/source/blender/blenkernel/intern/object_update.c b/source/blender/blenkernel/intern/object_update.c
index c5d267ace9d..3495804f743 100644
--- a/source/blender/blenkernel/intern/object_update.c
+++ b/source/blender/blenkernel/intern/object_update.c
@@ -349,55 +349,55 @@ void BKE_object_eval_uber_data(const EvaluationContext *eval_ctx,
 			break;
 	}
 
-#ifdef WITH_COPY_ON_WRITE
-	if (ob->type == OB_MESH) {
-		/* Quick hack to convert evaluated derivedMesh to Mesh. */
-		DerivedMesh *dm = ob->derivedFinal;
-		if (dm != NULL) {
-			Mesh *mesh = (Mesh *)ob->data;
-			Mesh *new_mesh = BKE_libblock_alloc_notest(ID_ME);
-			BKE_mesh_init(new_mesh);
-			/* Copy ID name so GS(new_mesh->id) works correct later on. */
-			BLI_strncpy(new_mesh->id.name, mesh->id.name, sizeof(new_mesh->id.name));
-			/* Copy materials so render engines can access them. */
-			new_mesh->mat = MEM_dupallocN(mesh->mat);
-			new_mesh->totcol = mesh->totcol;
-			DM_to_mesh(dm, new_mesh, ob, CD_MASK_MESH, true);
-			new_mesh->edit_btmesh = mesh->edit_btmesh;
-			/* Store result mesh as derived_mesh of object. This way we have
-			 * explicit  way to query final object evaluated data and know for sure
-			 * who owns the newly created mesh datablock.
-			 */
-			ob->mesh_evaluated = new_mesh;
-			/* TODO(sergey): This is kind of compatibility thing, so all render
-			 * engines can use object->data for mesh data for display. This is
-			 * something what we might want to change in the future.
-			 */
-			ob->data = new_mesh;
-			/* Save some memory by throwing DerivedMesh away. */
-			/* NOTE: Watch out, some tools might need it!
-			 * So keep around for now..
-			 */
-			/* Store original ID as a pointer in evaluated ID.
-			 * This way we can restore original object data when we are freeing
-			 * evaluated mesh.
-			 */
-			new_mesh->id.newid = &mesh->id;
-		}
+	if (DEG_depsgraph_use_copy_on_write()) {
+		if (ob->type == OB_MESH) {
+			/* Quick hack to convert evaluated derivedMesh to Mesh. */
+			DerivedMesh *dm = ob->derivedFinal;
+			if (dm != NULL) {
+				Mesh *mesh = (Mesh *)ob->data;
+				Mesh *new_mesh = BKE_libblock_alloc_notest(ID_ME);
+				BKE_mesh_init(new_mesh);
+				/* Copy ID name so GS(new_mesh->id) works correct later on. */
+				BLI_strncpy(new_mesh->id.name, mesh->id.name, sizeof(new_mesh->id.name));
+				/* Copy materials so render engines can access them. */
+				new_mesh->mat = MEM_dupallocN(mesh->mat);
+				new_mesh->totcol = mesh->totcol;
+				DM_to_mesh(dm, new_mesh, ob, CD_MASK_MESH, true);
+				new_mesh->edit_btmesh = mesh->edit_btmesh;
+				/* Store result mesh as derived_mesh of object. This way we have
+				 * explicit  way to query final object evaluated data and know for sure
+				 * who owns the newly created mesh datablock.
+				 */
+				ob->mesh_evaluated = new_mesh;
+				/* TODO(sergey): This is kind of compatibility thing, so all render
+				 * engines can use object->data for mesh data for display. This is
+				 * something what we might want to change in the future.
+				 */
+				ob->data = new_mesh;
+				/* Save some memory by throwing DerivedMesh away. */
+				/* NOTE: Watch out, some tools might need it!
+				 * So keep around for now..
+				 */
+				/* Store original ID as a pointer in evaluated ID.
+				 * This way we can restore original object data when we are freeing
+				 * evaluated mesh.
+				 */
+				new_mesh->id.newid = &mesh->id;
+			}
 #if 0
-		if (ob->derivedFinal != NULL) {
-			ob->derivedFinal->needsFree = 1;
-			ob->derivedFinal->release(ob->derivedFinal);
-			ob->derivedFinal = NULL;
-		}
-		if (ob->derivedDeform != NULL) {
-			ob->derivedDeform->needsFree = 1;
-			ob->derivedDeform->release(ob->derivedDeform);
-			ob->derivedDeform = NULL;
-		}
+			if (ob->derivedFinal != NULL) {
+				ob->derivedFinal->needsFree = 1;
+				ob->derivedFinal->release(ob->derivedFinal);
+				ob->derivedFinal = NULL;
+			}
+			if (ob->derivedDeform != NULL) {
+				ob->derivedDeform->needsFree = 1;
+				ob->derivedDeform->release(ob->derivedDeform);
+				ob->derivedDeform = NULL;
+			}
 #endif
+		}
 	}
-#endif
 
 	ob->recalc &= ~(OB_RECALC_DATA | OB_RECALC_TIME);
 }
diff --git a/source/blender/depsgraph/CMakeLists.txt b/source/blender/depsgraph/CMakeLists.txt
index 17a13b66aaa..b4509c7a61a 100644
--- a/source/blender/depsgraph/CMakeLists.txt
+++ b/source/blender/depsgraph/CMakeLists.txt
@@ -128,8 +128,4 @@ if(WITH_OPENSUBDIV)
 	add_definitions(-DWITH_OPENSUBDIV)
 endif()
 
-if(WITH_DEPSGRAPH_COPY_ON_WRITE)
-	add_definitions(-DWITH_COPY_ON_WRITE)
-endif()
-
 blender_add_lib(bf_depsgraph "${SRC}" "${INC}" "${INC_SYS}")
diff --git a/source/blender/depsgraph/DEG_depsgraph.h b/source/blender/depsgraph/DEG_depsgraph.h
index f925c37e23e..894adbee8c9 100644
--- a/source/blender/depsgraph/DEG_depsgraph.h
+++ b/source/blender/depsgraph/DEG_depsgraph.h
@@ -105,6 +105,9 @@ enum {
 extern "C" {
 #endif
 
+bool DEG_depsgraph_use_copy_on_write(void);
+void DEG_depsgraph_enable_copy_on_write(void);
+
 /* ************************************************ */
 /* Depsgraph API */
 
diff --git a/source/blender/depsgraph/intern/builder/deg_builder.cc b/source/blender/depsgraph/intern/builder/deg_builder.cc
index deee2227f81..587d2021b52 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder.cc
@@ -47,6 +47,7 @@ namespace DEG {
 
 void deg_graph_build_finalize(Depsgraph *graph)
 {
+	const bool use_copy_on_write = DEG_depsgraph_use_copy_on_write();
 	/* Re-tag IDs for update if it was tagged before the relations
 	 * update tag.
 	 */
@@ -63,9 +64,12 @@ void deg_graph_build_finalize(Depsgraph *graph)
 				id_node->tag_update(graph);
 			}
 		}
-#ifdef WITH_COPY_ON_WRITE
-		DEG_id_tag_update_ex(graph->bmain, id_node->id_orig, DEG_TAG_COPY_ON_WRITE);
-#endif
+		/* TODO(sergey): This is not ideal at all, since this forces
+		 * re-evaluaiton of the whole tree.
+		 */
+		if (use_copy_on_write) {
+			DEG_id_tag_update_ex(graph->bmain, id_node->id_orig, DEG_TAG_COPY_ON_WRITE);
+		}
 	}
 	GHASH_FOREACH_END();
 }
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc b/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc
index 02d20913177..a4c3c11d922 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc
@@ -174,7 +174,9 @@ DepsgraphNodeBuilder::~DepsgraphNodeBuilder()
 
 IDDepsNode *DepsgraphNodeBuilder::add_id_node(ID *id, bool do_tag)
 {
-#ifdef WITH_COPY_ON_WRITE
+	if (!DEG_depsgraph_use_copy_on_write()) {
+		return m_graph->add_id_node(id);
+	}
 	IDDepsNode *id_node = NULL;
 	ID *id_cow = (ID *)BLI_ghash_lookup(m_cow_id_hash, id);
 	if (id_cow != NULL) {
@@ -197,10 +199,6 @@ IDDepsNode *DepsgraphNodeBuilder::add_id_node(ID *id, bool do_tag)
 		    "", -1);
 		m_graph->operations.push_back(op_cow);
 	}
-#else
-	IDDepsNode *id_node = m_graph->add_id_node(id);
-	UNUSED_VARS(do_tag);
-#endif
 	return id_node;
 }
 
@@ -358,23 +356,25 @@ void DepsgraphNodeBuilder::begin_build(Main *bmain) {
 	}
 	FOREACH_NODETREE_END;
 
-#ifdef WITH_COPY_ON_WRITE
-	/* Store existing copy-on-write versions of datablock, so we can re-use
-	 * them for new ID nodes.
-	 */
-	m_cow_id_hash = BLI_ghash_ptr_new("Depsgraph id hash");
-	GHASH_FOREACH_BEGIN(IDDepsNode *, id_node, m_graph->id_hash)
-	{
-		if (GS(id_node->id_orig->name) != ID_SCE) {
-			continue;
-		}
-		if (deg_copy_on_write_is_expanded(id_node->id_cow)) {
-			BLI_ghash_insert(m_cow_id_hash, id_node->id_orig, id_node->id_cow);
-			id_node->id_cow = NULL;
+	if (DEG_depsgraph_use_copy_on_write()) {
+		/* Store existing copy-on-write versions of datablock, so we can re-use
+		 * them for new ID nodes.
+		 */
+		m_cow_id_hash = BLI_ghash_ptr_new("Depsgraph id hash");
+		GHASH_FOREACH_BEGIN(IDDepsNode *, id_node, m_graph->id_hash)
+		{
+			if (GS(id_node->id_orig->name) != ID_SCE) {
+				continue;
+			}
+			if (deg_copy_on_write_is_expanded(id_node->id_cow)) {
+				BLI_ghash_insert(m_cow_id_hash,
+				                 id_node->id_orig,
+				                 id_node->id_cow);
+				id_node->id_cow = NULL;
+			}
 		}
+		GHASH_FOREACH_END();
 	}
-	GHASH_FOREACH_END();
-#endif
 
 	/* Make sure graph has no nodes left from previous state. */
 	m_graph->clear_all_nodes();
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_nodes.h b/source/blender/depsgraph/intern/builder/deg_builder_nodes.h
index 7e28df1276d..dbb126e2078 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_nodes.h
+++ b/source/blender/depsgraph/intern/builder/deg_builder_nodes.h
@@ -32,6 +32,8 @@
 
 #include "intern/depsgraph_types.h"
 
+#include "DEG_depsgraph.h"  /* used for DEG_depsgraph_use_copy_on_write() */
+
 struct CacheFile;
 struct bGPdata;
 struct ListBase;
@@ -98,11 +100,12 @@ struct DepsgraphNodeBuilder {
 	/* For a given COW datablock get corresponding original one. */
 	template<typename T>
 	T *get_orig_datablock(const T *cow) const {
-#ifdef WITH_COPY_ON_WRITE
-		return (T *)cow->id.newid;
-#else
-		return (T *)cow;
-#endif
+		if (DEG_depsgraph_use_copy_on_write()) {
+			return (T *)cow->id.newid;
+		}
+		else {
+			return (T *)cow;
+		}
 	}
 
 	void begin_build(Main *bmain);
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_nodes_layer.cc b/source/blender/depsgraph/intern/builder/deg_builder_nodes_layer.cc
index b3a88d8ac4d..660d7fedb52 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_nodes_layer.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_nodes_layer.cc
@@ -96,12 +96,14 @@ void DepsgraphNodeBuilder::build_layer_collections(Scene *scene,
 
 void DepsgraphNodeBuilder::build_scene_layer_collections(Scene *scene)
 {
-#ifdef WITH_COPY_ON_WRITE
-	/* Make sure we've got ID node, so we can get pointer to CoW datablock. */
-	Scene *scene_cow = expand_cow_datablock(scene);
-#else
-	Scene *scene_cow = scene;
-#endif
+	Scene *scene_cow;
+	if (DEG_depsgraph_use_copy_on_write()) {
+		/* Make sure we've got ID node, so we can get pointer to CoW datablock. */
+		scene_cow = expand_cow_datablock(scene);
+	}
+	else {
+		scene_cow = scene;
+	}
 
 	LayerCollectionState state;
 	state.index = 0;
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_nodes_rig.cc b/source/blender/depsgraph/intern/builder/deg_builder_nodes_rig.cc
index eb7fbaefb95..20263e1d751 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_nodes_rig.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_nodes_rig.cc
@@ -138,18 +138,22 @@ void DepsgraphNodeBuilder::build_rig(Scene *scene, Object *object)
 {
 	bArmature *armature = (bArmature *)object->data;
 	const short armature_tag = armature->id.tag;
-#ifdef WITH_COPY_ON_WRITE
-	/* NOTE: We need to expand both object and armature, so this way we can
-	 * safely create object level pose.
-	 */
-	Scene *scene_cow = get_cow_datablock(scene);
-	Object *object_cow = expand_cow_datablock(object);
-	bArmature *armature_cow = expand_cow_datablock(armature);
-#else
-	Scene *scene_cow = scene;
-	Object *object_cow = object;
-	bArmature *armature_cow = armature;
-#endif
+	Scene *scene_cow;
+	Object *object_cow;
+	bArmature *armature_cow;
+	if (DEG_depsgraph_use_copy_on_write()) {
+		/* NOTE: We need to expand both object and armature, so this way we can
+		 * safely create object level pose.
+		 */
+		scene_cow = get_cow_datablock(scene);
+		object_cow = expand_cow_datablock(object);
+		armature_cow = expand_cow_datablock(armature);
+	}
+	else {
+		scene_cow = scene;
+		object_cow = object;
+		armature_cow = armature;
+	}
 	OperationDepsNode *op_node;
 
 	/* Animation and/or drivers linking posebones to base-armature used to
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
index 0c5150f2f42..10c4c44d14e 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
@@ -1803,18 +1803,18 @@ void DepsgraphRelationBuilder::build_lamp(Object *ob)
 	/* textures */
 	build_texture_stack(la->mtex);
 
-#ifdef WITH_COPY_ON_WRITE
-	/* Make sure copy on write of lamp data is always properly updated for
-	 * visible lamps.
-	 */
-	OperationKey ob_copy_on_write_key(&ob->id,
-	                                  DEG_NODE_TYPE_COPY_ON_WRITE,
-	                                  DEG_OPCODE_COPY_ON_WRITE);
-	OperationKey lamp_copy_on_write_key(lamp_id,
-	                                    DEG_NODE_TYPE_COPY_ON_WRITE,
-	                                    DEG_OPCODE_COPY_ON_WRITE);
-	add_relation(lamp_copy_on_write_key, ob_copy_on_write_key, "Eval Order");
-#endif
+	if (DEG_depsgraph_use_copy_on_write()) {
+		/* Make sure copy on write of lamp data is always properly updated for
+		 * visible lamps.
+		 */
+		OperationKey ob_copy_on_write_key(&ob->id,
+		                                  DEG_NODE_TYPE_COPY_ON_WRITE,
+		                                  DEG_OPCODE_COPY_ON_WRITE);
+		OperationKey lamp_copy_on_write_key(lamp_id,
+		                                    DEG_NODE_TYPE_COPY_ON_WRITE,
+		                                    DEG_OPCODE_COPY_ON_WRITE);
+		add_relation(lamp_copy_on_write_key, ob_copy_on_write_key, "Eval Order");
+	}
 }
 
 void DepsgraphRelationBuilder::build_nodetree(bNodeTree *ntree)
diff --git a/source/blender/depsgraph/intern/depsgraph.cc b/source/blender/depsgraph/intern/depsgraph.cc
index 81a4f2bc0cc..b146d4a432b 100644
--- a/source/blender/depsgraph/intern/depsgraph.cc
+++ b/source/blender/depsgraph/intern/depsgraph.cc
@@ -62,6 +62,18 @@ extern "C" {
 #include "intern/depsgraph_intern.h"
 #include "util/deg_util_foreach.h"
 
+static bool use_copy_on_write = true;
+
+bool DEG_depsgraph_use_copy_on_write(void)
+{
+	return use_copy_on_write;
+}
+
+void DEG_depsgraph_enable_copy_on_write(void)
+{
+	use_copy_on_write = true;
+}
+
 namespace DEG {
 
 static DEG_EditorUpdateIDCb deg_editor_update_id_cb = NULL;
@@ -252,14 +264,6 @@ DepsNode *Depsgraph::find_node_from_pointer(const PointerRNA *ptr,
 
 /* Node Management ---------------------------- */
 
-#ifndef WITH_COPY_ON_WRITE
-static void id_node_deleter(void *value)
-{
-	IDDepsNode *id_node = reinterpret_cast<IDDepsNode *>(value);
-	OBJECT_GUARDED_DELETE(id_node, IDDepsNode);
-}
-#endif
-
 TimeSourceDepsNode *Depsgraph::add_time_source()
 {
 	if (time_source == NULL) {
@@ -305,9 +309,6 @@ IDDepsNode *Depsgraph::add_id_node(ID *id, bool do_tag, ID *id_cow_hint)
 
 void Depsgraph::clear_id_nodes()
 {
-#ifndef WITH_COPY_ON_WRITE
-	BLI_ghash_clear(id_hash, NULL, id_node_deleter);
-#else
 	/* Stupid workaround to ensure we free IDs in a proper order. */
 	GHASH_FOREACH_BEGIN(IDDepsNode *, id_node, id_hash)
 	{
@@ -331,7 +332,6 @@ void Depsgraph::clear_id_nodes()
 		OBJECT_GUARDED_DELETE(id_node, IDDepsNode);
 	}
 	GHASH_FOREACH_END();
-#endif
 }
 
 /* Add new relationship between two nodes. */
diff --git a/source/blender/depsgraph/intern/depsgraph_build.cc b/source/blender/depsgraph/intern/depsgraph_build.cc
index e21c3d29aa5..e4b6434b9c7 100644
--- a/source/blender/depsgraph/intern/depsgraph_build.cc
+++ b/source/blender/depsgraph/intern/depsgraph_build.cc
@@ -216,9 +216,9 @@ void DEG_graph_build_from_scene(Depsgraph *graph, Main *bmain, Scene *scene)
 	DEG::DepsgraphRelationBuilder relation_builder(deg_graph);
 	relation_builder.begin_build(bmain);
 	relation_builder.build_scene(bmain, scene);
-#ifdef WITH_COPY_ON_WRITE
-	relation_builder.build_copy_on_write_relations();
-#endif
+	if (DEG_depsgraph_use_copy_on_write()) {
+		relation_builder.build_copy_on_write_relations();
+	}
 
 	/* Detect and solve cycles. */
 	DEG::deg_graph_detect_cycles(deg_graph);
diff --git a/source/blender/depsgraph/intern/depsgraph_tag.cc b/source/blender/depsgraph/intern/depsgraph_tag.cc
index 0df2420d662..927593b6d8f 100644
--- a/source/blender/depsgraph/intern/depsgraph_tag.cc
+++ b/source/blender/depsgraph/intern/depsgraph_tag.cc
@@ -269,16 +269,17 @@ void id_tag_update_shading(Depsgraph *graph, IDDepsNode *id_node)
 	shading_comp->tag_update(graph);
 }
 
-#ifdef WITH_COPY_ON_WRITE
 /* Tag corresponding to DEG_TAG_COPY_ON_WRITE. */
 void id_tag_update_copy_on_write(Depsgraph *graph, IDDepsNode *id_node)
 {
+	if (!DEG_depsgraph_use_copy_on_write()) {
+		return;
+	}
 	ComponentDepsNode *cow_comp =
 	        id_node->find_component(DEG_NODE_TYPE_COPY_ON_WRITE);
 	OperationDepsNode *cow_node = cow_comp->get_entry_operation();
 	cow_node->tag_update(graph);
 }
-#endif
 
 void id_tag_update_ntree_special(Main *bmain, Depsgraph *graph, ID *id, int flag)
 {
@@ -320,16 +321,16 @@ void deg_graph_id_tag_update(Main *bmain, Depsgraph *graph, ID *id, int flag)
 	}
 	if (flag & OB_RECALC_DATA) {
 		id_tag_update_object_data(graph, id_node);
-#ifdef WITH_COPY_ON_WRITE
-		if (flag & DEG_TAG_COPY_ON_WRITE) {
-			const ID_Type id_type = GS(id_node->id_orig->name);
-			if (id_type == ID_OB) {
-				Object *object = (Object *)id_node->id_orig;
-				ID *ob_data = (ID *)object->data;
-				DEG_id_tag_update_ex(bmain, ob_data, flag);
+		if (DEG_depsgraph_use_copy_on_write()) {
+			if (flag & DEG_TAG_COPY_ON_WRITE) {
+				const ID_Type id_type = GS(id_node->id_orig->name);
+				if (id_type == ID_OB) {
+					Object *object = (Object *)id_node->id_orig;
+					ID *ob_data = (ID *)object->data;
+					DEG_id_tag_update_ex(bmain, ob_data, flag);
+				}
 			}
 		}
-#endif
 	}
 	if (flag & OB_RECALC_TIME) {
 		id_tag_update_object_time(graph, id_node);
@@ -340,11 +341,9 @@ void deg_graph_id_tag_update(Main *bmain, Depsgraph *graph, ID *id, int flag)
 	if (flag & DEG_TAG_SHADING_UPDATE) {
 		id_tag_update_shading(graph, id_node);
 	}
-#ifdef WITH_COPY_ON_WRITE
 	if (flag & DEG_TAG_COPY_ON_WRITE) {
 		id_tag_update_copy_on_write(graph, id_node);
 	}
-#endif
 	id_tag_update_ntree_special(bmain, graph, id, flag);
 }
 
diff --git a/source/blender/depsgraph/intern/eval/deg_eval_flush.cc b/source/blender/depsgraph/intern/eval/deg_eval_flush.cc
index 54a3a499e36..86e69458f41 100644
--- a/source/blender/depsgraph/intern/eval/deg_eval_flush.cc
+++ b/source/blender/depsgraph/intern/eval/deg_eval_flush.cc
@@ -82,6 +82,7 @@ static void flush_init_func(void *data_v, int i)
  */
 void deg_graph_flush_updates(Main *bmain, Depsgraph *graph)
 {
+	const bool use_copy_on_write = DEG_depsgraph_use_copy_on_write();
 	/* Sanity check. */
 	if (graph == NULL) {
 		return;
@@ -146,18 +147,17 @@ void deg_graph_flush_updates(Main *bmain, Depsgraph *graph)
 			}
 
 			if (comp_node->done != COMPONENT_STATE_DONE) {
-#ifdef WITH_COPY_ON_WRITE
 				/* Currently this is needed to get ob->mesh to be replaced with
 				 * original mesh (rather than being evaluated_mesh).
 				 *
 				 * TODO(sergey): This is something we need to avoid.
 				 */
-				if (comp_node->depends_on_cow()) {
+				if (use_copy_on_write && comp_node->depends_on_cow()) {
 					ComponentDepsNode *cow_comp =
 					        id_node->find_component(DEG_NODE_TYPE_COPY_ON_WRITE);
 					cow_comp->tag_update(graph);
 				}
-#endif
+
 				Object *object = NULL;
 				if (GS(id_orig->name) == ID_OB) {
 					object = (Object *)id_orig;
diff --git a/source/blender/depsgraph/intern/nodes/deg_node.cc b/source/blender/depsgraph/intern/nodes/deg_node.cc
index 5e7ed249365..b313059e1bd 100644
--- a/source/blender/depsgraph/intern/nodes/deg_node.cc
+++ b/source/blender/depsgraph/intern/nodes/deg_node.cc
@@ -177,7 +177,14 @@ void IDDepsNode::init(const ID *id, const char *UNUSED(subdata))
 
 void IDDepsNode::init_copy_on_write(ID *id_cow_hint)
 {
-#ifdef WITH_COPY_ON_WRITE
+	/* Early output for non-copy-on-write case: we keep CoW pointer same as
+	 * an original one.
+	 */
+	if (!DEG_depsgraph_use_copy_on_write()) {
+		UNUSED_VARS(id_cow_hint);
+		id_cow = id_orig;
+		return;
+	}
 	/* Create pointer as early as possible, so we can use it for function
 	 * bindings. Rest of data we'll be copying to the new datablock when
 	 * it is actually needed.
@@ -200,10 +207,6 @@ void IDDepsNode::init_copy_on_write(ID *id_cow_hint)
 	else {
 		id_cow = id_orig;
 	}
-#else
-	UNUSED_VARS(id_cow_hint);
-	id_cow = id_orig;
-#endif
 }
 
 /* Free 'id' node. */
@@ -222,7 +225,6 @@ void IDDepsNode::destroy()
 	               id_deps_node_hash_key_free,
 	               id_deps_node_hash_value_free);
 
-#ifdef WITH_COPY_ON_WRITE
 	/* Free memory used by this CoW ID. */
 	if (id_cow != id_orig && id_cow != NULL) {
 		deg_free_copy_on_write_datablock(id_cow);
@@ -230,7 +232,7 @@ void IDDepsNode::destroy()
 		DEG_COW_PRINT("Destroy CoW for %s: id_orig=%p id_cow=%p\n",
 		              id_orig->name, id_orig, id_cow);
 	}
-#endif
+
 	/* Tag that the node is freed. */
 	id_orig = NULL;
 }