Mo implementation for If with tf extractor (#6662)

* Add tf2.x impl for If

* Fix ir_engine

* Fix opset

* Fix BOM file

* Added new test

* Fix comments

* Add subgraph_utils

* Fix comments

* Fix transform

* code refactoring

* Fix description

* rewrite support for empty tensor in if

* added onnx extractor

* delete onnx_if

* fix bug with fake_outputs

* Fix test

* Fix control_flow and fix commentaries

* create method results_mapping_and_finding_fake_outputs(output_nodes_in_subgraph,

model-optimizer/automation/package_BOM.txt

@@ -436,6 +436,7 @@ extensions/front/tf/GatherTree_ext.py
 extensions/front/tf/GNMT_DynamicSequenceLengths.py
 extensions/front/tf/identity_ext.py
 extensions/front/tf/identityN_to_identity.py
+extensions/front/tf/if_ext.py
 extensions/front/tf/InterpolateTransposes.py
 extensions/front/tf/IteratorGetNext_ext.py
 extensions/front/tf/log_softmax_ext.py
@@ -701,6 +702,7 @@ extensions/ops/GRU.py
 extensions/ops/GRUCell.py
 extensions/ops/hard_sigmoid.py
 extensions/ops/identity.py
+extensions/ops/If.py
 extensions/ops/instance_normalization.py
 extensions/ops/interp.py
 extensions/ops/interpolate.py
@@ -927,6 +929,7 @@ mo/front/tf/extractors/native_tf.py
 mo/front/tf/extractors/pack.py
 mo/front/tf/extractors/random_uniform.py
 mo/front/tf/extractors/strided_slice.py
+mo/front/tf/extractors/subgraph_utils.py
 mo/front/tf/extractors/utils.py
 mo/front/tf/graph_utils.py
 mo/front/tf/loader.py
@@ -1050,6 +1053,7 @@ mo/utils/ir_reader/extenders/experimental_extender.py
 mo/utils/ir_reader/extenders/ExtractImagePatches_extender.py
 mo/utils/ir_reader/extenders/fakequantize_extender.py
 mo/utils/ir_reader/extenders/GRUCell_extender.py
+mo/utils/ir_reader/extenders/if_extender.py
 mo/utils/ir_reader/extenders/interpolate_extender.py
 mo/utils/ir_reader/extenders/loop_extender.py
 mo/utils/ir_reader/extenders/LSTMCell_extender.py

model-optimizer/extensions/front/tf/if_ext.py

@@ -0,0 +1,69 @@
+# Copyright (C) 2018-2021 Intel Corporation
+# SPDX-License-Identifier: Apache-2.0
+
+from extensions.ops.If import If
+from extensions.ops.parameter import Parameter
+from mo.front.common.register_custom_ops import check_for_duplicates
+from mo.front.extractor import FrontExtractorOp, extract_node_attrs
+from mo.front.tf.extractor import tf_op_extractor, tf_op_extractors
+from mo.front.tf.extractors.subgraph_utils import update_body_graph, convert_graph_inputs_to_parameters, \
+    get_graph_proto, create_internal_graph
+from mo.graph.graph import Node, Graph
+
+
+def extract_if(cls, if_node: Node):
+    If.update_node_stat(if_node, {})
+
+    # check that required body and condition functions exist in the graph library
+    main_graph = if_node.graph
+    then_graph_proto = get_graph_proto(main_graph, 'then_branch', if_node)
+    else_graph_proto = get_graph_proto(main_graph, 'else_branch', if_node)
+
+    then_graph = create_internal_graph(main_graph)
+    if_node['then_graph'] = then_graph
+
+    else_graph = create_internal_graph(main_graph)
+    if_node['else_graph'] = else_graph
+
+    # create Parameter nodes for the then/else graphs
+    for input_index, (body_graph, body_graph_proto) in enumerate(zip((then_graph, else_graph), (then_graph_proto,
+                                                                                                else_graph_proto))):
+
+        body_parameters, body_parameter_names = convert_graph_inputs_to_parameters(body_graph, body_graph_proto)
+
+        # update the If body graph with the body function graph
+        body_results = []
+        update_body_graph(body_graph, body_graph_proto, body_parameter_names, body_results)
+
+        body_graph.stage = 'front'
+
+        # connect external input ports with body parameter nodes except input with condition
+        for idx in range(0, len(body_parameters)):
+            If.connect_body_input(if_node, not input_index, idx + 1, body_parameters[idx])
+
+        # connect body outputs with If operation output ports
+        for idx in range(len(body_results)):
+            If.connect_body_output(if_node, not input_index, idx, body_results[idx])
+
+        # run function to parse body nodes attributes similar to the main graph
+        extract_node_attrs(body_graph, lambda node: tf_op_extractor(node, check_for_duplicates(tf_op_extractors)))
+
+    return cls.enabled
+
+
+class IfExtractor(FrontExtractorOp):
+    op = 'If'
+    enabled = True
+
+    @classmethod
+    def extract(cls, if_node: Node):
+        return extract_if(cls, if_node)
+
+
+class StatelessIfExtractor(FrontExtractorOp):
+    op = 'StatelessIf'
+    enabled = True
+
+    @classmethod
+    def extract(cls, if_node: Node):
+        return extract_if(cls, if_node)

model-optimizer/extensions/front/tf/while_ext.py

@@ -1,68 +1,14 @@
 # Copyright (C) 2018-2021 Intel Corporation
 # SPDX-License-Identifier: Apache-2.0
 
-import copy
-
 from extensions.ops.loop import Loop
 from extensions.ops.parameter import Parameter
 from mo.front.common.register_custom_ops import check_for_duplicates
 from mo.front.extractor import extract_node_attrs, FrontExtractorOp
 from mo.front.tf.extractor import tf_op_extractor, tf_op_extractors, create_tf_edge
-from mo.front.tf.extractors.utils import tf_dtype_extractor
+from mo.front.tf.extractors.subgraph_utils import update_body_graph, convert_graph_inputs_to_parameters, \
+    get_graph_proto, create_internal_graph
 from mo.graph.graph import add_opoutput, Graph, Node
-from mo.ops.op import PermuteAttrs
-
-
-def update_body_graph(body_graph: Graph, subgraph_proto: dict,
-                      body_parameter_names: list, body_results: list):
-    """
-    Updates the loop body graph with a sub-graph (for body or condition functions)
-    :param body_graph: a loop body graph to be updated
-    :param subgraph_proto: a sub-graph in a protobuf format to be added into the loop body graph
-    :param body_parameter_names: a (unchanged) list of parameters in the loop body graph
-    :param body_results: a list of Result nodes that is extended with a list from a sub-graph
-    """
-    # create a map from a node name in original model to a name in a loop body graph assuming
-    # that names in the original model are unique
-    # initially, the map contains names for parameters that are common for the body and condition graphs
-    map_original_name = {}
-    for idx, pb_node in enumerate(subgraph_proto['input_arg']):
-        map_original_name[pb_node.name] = body_parameter_names[idx]
-
-    # walk through all nodes (non-parameter and non-result nodes) and add into the loop body graph
-    for pb_node in subgraph_proto['node_def']:
-        # create an NX node
-        id = body_graph.unique_id(pb_node.name)
-        map_original_name[pb_node.name] = id
-        body_graph.add_node(id, pb=pb_node, kind='op')
-        if hasattr(body_graph, 'op_names_statistic') and hasattr(pb_node, 'op'):
-            body_graph.op_names_statistic[pb_node.op] += 1
-
-        # add incoming edges based on data_nodes_map
-        for dst_port, inp in enumerate(pb_node.input):
-            orig_src_id = inp.split(":")[0]
-
-            # TODO: avoid this temporal workaround for TF 2.4 or higher RNN layers:
-            #  skip control flow dependency
-            if orig_src_id[0] == '^':
-                continue
-
-            src_id = map_original_name[orig_src_id]
-            src_port = 0 if len(inp.split(":")) == 1 else int(inp.split(":")[-1])
-            assert (body_graph.has_node(src_id))
-
-            body_graph.add_edges_from([create_tf_edge(src_id + ":" + str(src_port), id, dst_port)])
-
-    # create Result nodes in the loop body graph
-    for output in subgraph_proto['output_arg']:
-        output_name = subgraph_proto['ret'][output.name]
-        orig_src_id = output_name.split(":")[0]
-        src_id = map_original_name[orig_src_id]
-        src_port = 0 if len(output_name.split(":")) == 1\
-            else int(output_name.split(":")[-1])
-        assert body_graph.has_node(src_id), 'The body graph does not contain output with name "{}"'.format(
-            src_id)
-        body_results.append(Node(body_graph, add_opoutput(body_graph, src_id, src_port, False)))
 
 
 class WhileExtractor(FrontExtractorOp):
@@ -77,49 +23,16 @@ class WhileExtractor(FrontExtractorOp):
     @classmethod
     def extract(cls, loop_node):
         Loop.update_node_stat(loop_node, {})
-        loop_name = loop_node.soft_get('name', loop_node.id)
 
         # check that required body and condition functions exist in the graph library
         main_graph = loop_node.graph
-        body_graph_name = loop_node.pb.attr['body'].func.name
+        body_graph_proto = get_graph_proto(main_graph, 'body', loop_node)
-        cond_graph_name = loop_node.pb.attr['cond'].func.name
+        cond_graph_proto = get_graph_proto(main_graph, 'cond', loop_node)
-        assert 'library' in main_graph.graph, 'The graph does not contain a library that is required ' \
-                                              'by node with name "{}".'.format(loop_name)
-        library_graph = main_graph.graph['library']
 
-        assert body_graph_name in library_graph, 'The library does not contain a function with name "{}" ' \
+        body_graph = create_internal_graph(main_graph)
-                                                 'that is required by node ' \
-                                                 'with name "{}".'.format(body_graph_name, loop_name)
-        body_graph_proto = library_graph[body_graph_name]
-
-        assert cond_graph_name in library_graph, 'The library does not contain a function with name "{}" ' \
-                                                 'that is required by node ' \
-                                                 'with name "{}".'.format(cond_graph_name, loop_name)
-        cond_graph_proto = library_graph[cond_graph_name]
-
-        body_graph = Graph()
-        # fill the body graph
-        for attr_key in main_graph.graph.keys():
-            if attr_key != 'library':
-                body_graph.graph[attr_key] = copy.deepcopy(main_graph.graph[attr_key])
-            else:
-                # it is sufficient to have a link to the library
-                body_graph.graph['library'] = main_graph.graph['library']
         loop_node['body'] = body_graph
-
         # create Parameter nodes for the body graph
-        body_parameters = []
+        body_parameters, body_parameter_names = convert_graph_inputs_to_parameters(body_graph, body_graph_proto)
-        body_parameter_names = []
-        for idx, pb_node in enumerate(body_graph_proto['input_arg']):
-            param_id = body_graph.unique_id(pb_node.name)
-            body_graph.add_node(param_id, name=param_id, kind='op', op='Parameter', pb=None, shape=None)
-            parameter_node = Node(body_graph, pb_node.name)
-            Parameter.update_node_stat(parameter_node,
-                                       {'data_type': tf_dtype_extractor(pb_node.type),
-                                        'permute_attrs': PermuteAttrs().update_attrs(attrs=[('shape', 'output:0')])}
-                                       )
-            body_parameters.append(parameter_node)
-            body_parameter_names.append(param_id)
 
         # update the loop body graph with the body function graph
         body_results = []
@@ -172,7 +85,7 @@ class WhileExtractor(FrontExtractorOp):
             Loop.add_back_edge(loop_node, body_parameters[idx], body_results[idx])
 
         # connect body outputs with Loop operation output ports except the execution condition result
-        for idx in range(len(body_results)-1):
+        for idx in range(len(body_results) - 1):
             Loop.connect_body_output(loop_node, idx, body_results[idx])
 
         # run function to parse body nodes attributes similar to the main graph

model-optimizer/extensions/load/tf/loader.py

@@ -138,8 +138,8 @@ def graph_or_sub_graph_has_nhwc_ops(graph: Graph):
             NHWC_conv_detected = True
             break
 
-        # for the Loop node we need to check that the body does not contain marker ops as well
+        if node.has('sub_graphs'):
-        if node.op == 'Loop':
+            for sub_graph_name in node['sub_graphs']:
-            NHWC_conv_detected |= graph_or_sub_graph_has_nhwc_ops(node.body)
+                NHWC_conv_detected |= graph_or_sub_graph_has_nhwc_ops(node.soft_get(sub_graph_name))
-            # TODO check for If op when it is implemented
+
     return NHWC_conv_detected

model-optimizer/extensions/ops/If.py

@@ -0,0 +1,328 @@
+# Copyright (C) 2018-2021 Intel Corporation
+# SPDX-License-Identifier: Apache-2.0
+
+import logging as log
+import numpy as np
+
+from mo.front.common.partial_infer.utils import int64_array
+from mo.graph.graph import Node, Graph
+from mo.middle.passes.infer import partial_infer
+from mo.ops.op import Op
+
+
+class If(Op):
+    """
+    If operation is an operation which has an input with condition which defines what sub-graph "then" or "else" to be
+    executed.
+    """
+    op = 'If'
+    enabled = False
+
+    def __init__(self, graph: Graph, attrs: dict):
+        base_attrs = {
+            'type': self.op,
+            'op': self.op,
+            'then_graph': None,  # an Graph object with a "then" body sub-graph (condition is True)
+            'else_graph': None,  # an Graph object with a "else" body sub-graph (condition is False)
+            'sub_graphs': ['then_graph', 'else_graph'],  # built-in attribute with all sub-graphs
+            'version': 'opset8',
+            'infer': self.infer,
+            'type_infer': self.type_infer,
+        }
+        base_attrs.update(attrs)
+        super().__init__(graph, base_attrs, attrs)
+
+    def port_map_attrs(self):
+        return [
+            'external_port_id',
+            'internal_layer_id'
+        ]
+
+    @staticmethod
+    def connect_body_input(if_node: Node, condition: bool, if_input_port_idx: int, body_parameter: Node):
+        """
+        Update the specified body parameter and connect it with If input
+
+        :param if_node: the If node
+        :param condition: the boolean defining a condition (then/else) graph to add connect the body
+        :param if_input_port_idx: the input port index to connect
+        :param body_parameter: the body parameter node to connect
+        :return: None
+        """
+        assert if_node.soft_get('op') == 'If'
+        assert body_parameter.soft_get('op') == 'Parameter'
+        sub_graph = if_node.then_graph if condition else if_node.else_graph
+        assert body_parameter.id in sub_graph
+        body_parameter['input_id'] = if_input_port_idx
+
+    @staticmethod
+    def connect_body_output(if_node: Node, condition: bool, if_output_port_idx: int, internal_result: Node):
+        """
+        Update the specified output port and connect it with If output
+
+        :param if_node: the If node
+        :param condition: the boolean defining a condition (then/else) graph to add connect the body
+        :param if_output_port_idx: the output port index to connect
+        :param internal_result: the body Result node to connect
+        :return: None
+        """
+        assert if_node.soft_get('op') == 'If'
+        assert internal_result.soft_get('op') == 'Result'
+        sub_graph = if_node.then_graph if condition else if_node.else_graph
+        assert internal_result.id in sub_graph
+        internal_result['output_id'] = if_output_port_idx
+
+    @staticmethod
+    def update_body_parameters_type(if_node: Node, condition: bool):
+        """
+        Update the data type for If body Parameter nodes based on data type of the outer graph nodes producing data
+        for them.
+
+        :param if_node: The If node
+        :param condition: the boolean defining a condition (then/else) graph
+        :return: None
+        """
+        assert if_node.soft_get('type') == 'If'
+
+        subgraph = if_node.then_graph if condition else if_node.else_graph
+        for node in subgraph.get_op_nodes():
+            if node.has('input_id'):
+                assert node.soft_get('type') == 'Parameter'
+                input_port_id = node['input_id']
+                input_type = if_node.in_port(input_port_id).get_data_type()
+                node.data_type = input_type
+                log.debug('Updated data type for the body node with name "{}" with value {}'
+                          .format(node.name, node.data_type))
+
+    @staticmethod
+    def update_body_parameters_shape(if_node: Node, condition: bool):
+        """
+        Update shape for If body parameters.
+
+        :param if_node: The If node
+        :param condition: the boolean defining a condition (then/else) graph to add connect the body
+        :return: None
+        """
+        subgraph = if_node.then_graph if condition else if_node.else_graph
+        for node in subgraph.get_op_nodes():
+            if node.has('input_id'):
+                assert node.soft_get('type') == 'Parameter'
+                input_port_id = node['input_id']
+                input_shape = if_node.in_port(input_port_id).data.get_shape()
+                if node.soft_get('shape', None) is None:
+                    node['shape'] = None
+                node.shape = input_shape.copy()
+                log.debug('Updated shape for the body node with name "{}" with value {}'
+                          .format(node.soft_get('name', node.soft_get('id')), node.shape))
+
+    @staticmethod
+    def results_mapping_and_finding_fake_outputs(output_nodes_in_subgraph, branch_name, outputs_mapping):
+        """
+        This method checked result nodes in subgraph and set map between output from If operation and internal subgraph
+        result. Also This method return True if internal graph has fake results.
+
+        :param output_nodes_in_subgraph: Result node with attribute 'output_id'
+        :param branch_name: name of subgraph
+        :param outputs_mapping: map between If operation output ID and subgraph results
+
+        :return: True if all results of subgraph are empty tensors
+        """
+        graph_contain_fake_outputs = True
+
+        for output_node in output_nodes_in_subgraph:
+            assert output_node.soft_get('type') == 'Result'
+            port_id = output_node['output_id']
+            assert port_id in outputs_mapping.keys(), 'Incorrect mapping then_graph outputs with {0} outputs! ' \
+                                                      'Can\'t find port with ID {1} in If operation.' \
+                .format(output_node.name, port_id)
+            outputs_mapping[port_id][branch_name] = output_node
+            out_node_shape = output_node.in_port(0).data.get_shape()
+            graph_contain_fake_outputs = graph_contain_fake_outputs and np.any(out_node_shape == 0)
+        return graph_contain_fake_outputs
+
+    @staticmethod
+    def update_if_output_ports_shape(if_node: Node):
+        """
+        Update shape and values for If output ports.
+
+        :param if_node: The If node to update output ports and shapes
+        :return: None
+        """
+
+        then_outputs = [node for node in if_node.then_graph.get_op_nodes() if node.has('output_id')]
+        else_outputs = [node for node in if_node.else_graph.get_op_nodes() if node.has('output_id')]
+        outputs_mapping = {}
+        outputs_number = len(if_node.out_ports())
+
+        if outputs_number == 0 and len(if_node.out_ports(control_flow=True)) != 0:
+            # Some models have if with control flow outputs.
+            # These shape inference for such ifs
+            # TODO: need to rethink and redo support for control flow edges in if operation
+            for node in if_node.out_nodes(control_flow=True).values():
+                node.shape = int64_array([])
+            return
+
+        for port_id in if_node.out_ports().keys():
+            outputs_mapping[port_id] = {}
+
+        # variables then_contains_fake_outputs/else_contains_fake_outputs contains True value
+        # if all outputs from then_body/else_body have shape [0]. It means then_body/else_body does not return data
+        # and further shape_inference for this branch is not possible.
+        # TODO: exclude support fake_outputs from this code when we will support shape_inference with empty tensors
+
+        then_contains_fake_outputs = \
+            If.results_mapping_and_finding_fake_outputs(then_outputs, 'then_graph', outputs_mapping)
+        else_contains_fake_outputs = \
+            If.results_mapping_and_finding_fake_outputs(else_outputs, 'else_graph', outputs_mapping)
+
+        # use_then_shape is True when else_body or when both bodies do not return data. If use_then_shape is True If's
+        # outputs will have the same shapes as then_body results
+        use_then_shape = else_contains_fake_outputs or not then_contains_fake_outputs
+
+        for port_id in outputs_mapping:
+            then_else_nodes = outputs_mapping[port_id]
+            assert 'then_graph' in then_else_nodes.keys(), 'then_graph does not connect with If.out_port[{0}] ' \
+                                                           'in {1} node!'.format(port_id, if_node.name)
+            assert 'else_graph' in then_else_nodes.keys(), 'else_graph does not connect with If.out_port[{0}] ' \
+                                                           'in {1} node!'.format(port_id, if_node.name)
+
+            then_shape = then_else_nodes['then_graph'].in_port(0).data.get_shape()
+            else_shape = then_else_nodes['else_graph'].in_port(0).data.get_shape()
+
+            if not (then_shape == else_shape).all():
+                log.debug("If node {0} has dynamic output [{1}] because output shape from then_graph is {2} and "
+                          "else_graph {3}".format(if_node.name, port_id, then_shape, else_shape))
+            if_node.out_port(port_id).data.set_shape(then_shape if use_then_shape else else_shape)
+
+    @staticmethod
+    def update_if_output_ports_type(if_node: Node):
+        """
+        Update types for If output ports.
+
+        :param if_node: The If node to update output ports and types
+        :return: None
+        """
+        then_outputs = [node for node in if_node.then_graph.get_op_nodes() if node.has('output_id')]
+        else_outputs = [node for node in if_node.else_graph.get_op_nodes() if node.has('output_id')]
+        outputs_mapping = {}
+        outputs_number = len(if_node.out_ports())
+        assert outputs_number == len(then_outputs), 'Incorrect number outputs in then_graph of If with"' \
+                                                    'name {0}! then_graph must has {1} outputs' \
+            .format(if_node.name, outputs_number)
+        assert outputs_number == len(else_outputs), 'Incorrect number outputs in else_graph of If with"' \
+                                                    'name {0}! else_graph must has {1} outputs' \
+            .format(if_node.name, outputs_number)
+        for port_id in if_node.out_ports().keys():
+            outputs_mapping[port_id] = {}
+        port_ids = outputs_mapping.keys()
+        for then_output_node in then_outputs:
+            assert then_output_node.soft_get('type') == 'Result'
+            port_id = then_output_node['output_id']
+            assert port_id in port_ids, 'Incorrect mapping then_graph outputs with {0} outputs! ' \
+                                        'Can\'t find port with ID {1} in If operation.' \
+                .format(then_output_node.name, port_id)
+            outputs_mapping[port_id]['then_graph'] = then_output_node
+
+        for else_output_node in else_outputs:
+            assert else_output_node.soft_get('type') == 'Result'
+            port_id = else_output_node['output_id']
+            assert port_id in port_ids, 'Incorrect mapping then_graph outputs with {0} outputs! ' \
+                                        'Can\'t find port with ID {1} in If operation.' \
+                .format(else_output_node.name, port_id)
+            outputs_mapping[port_id]['else_graph'] = else_output_node
+
+        for port_id in outputs_mapping:
+            then_else_nodes = outputs_mapping[port_id]
+            assert 'then_graph' in then_else_nodes.keys(), 'then_graph does not connect with If.out_port[{0}] ' \
+                                                           'in {1} node!'.format(port_id, if_node.name)
+            assert 'else_graph' in then_else_nodes.keys(), 'else_graph does not connect with If.out_port[{0}] ' \
+                                                           'in {1} node!'.format(port_id, if_node.name)
+            then_type = then_else_nodes['then_graph'].in_port(0).get_data_type()
+            else_type = then_else_nodes['else_graph'].in_port(0).get_data_type()
+            assert then_type == else_type, 'Cannot get type for if.out_port[{0}]! ' \
+                                           'Types in then_graph and else_graph are not equal!'.format(port_id)
+            if_node.out_port(port_id).set_data_type(then_type)
+
+    @staticmethod
+    def re_numerate_internal_id_and_get_if_id(if_node):
+        """
+        This method is called before IR generation. This method sets internal_layer_id.
+
+        :param if_node: The If node where is necessary to set internal_layer_id in bodies.
+        :return: if_node
+        """
+        then_graph_nodes = if_node.then_graph.nodes()
+        for idx in range(len(if_node.then_graph.get_op_nodes())):
+            then_graph_nodes[idx]['internal_layer_id'] = idx
+        else_graph_nodes = if_node.else_graph.nodes()
+        for idx in range(len(if_node.else_graph.get_op_nodes())):
+            else_graph_nodes[idx]['internal_layer_id'] = idx
+        return if_node.node
+
+    def substitute_ie_attrs(self, new_attrs: dict):
+        """
+        Replace standard list of attribute in layer/data by attributes
+        delivered by backend_attrs
+        """
+
+        port_map_attrs = self.port_map_attrs()
+        new_attrs.update({
+            'IE': [(
+                'layer',
+                [('id', lambda node: self.re_numerate_internal_id_and_get_if_id(node)), 'name', 'type', 'version'],
+                [
+                    '@ports',
+                    ('then_port_map', [], [
+                        ('@list', lambda node: self.generate_port_map(node, True, 'in'),
+                         ('input', port_map_attrs, [])),
+                        ('@list', lambda node: self.generate_port_map(node, True, 'out'),
+                         ('output', port_map_attrs, [])),
+                    ]),
+                    ('else_port_map', [], [
+                        ('@list', lambda node: self.generate_port_map(node, False, 'in'),
+                         ('input', port_map_attrs, [])),
+                        ('@list', lambda node: self.generate_port_map(node, False, 'out'),
+                         ('output', port_map_attrs, [])),
+                    ]),
+                    ('then_body', [], [('@network', 'then_graph')]),
+                    ('else_body', [], [('@network', 'else_graph')]),
+                ])]
+        })
+
+    @staticmethod
+    def generate_port_map(if_node: Node, condition: bool, dir: str):
+        """
+        Extract port_map attributes from if_node and its subgraphs attributes.
+
+        :param if_node: The If node
+        :param condition: the boolean defining a condition (then/else) graph
+        :param dir: the str value defining type (for inputs or for putputs) of port_map
+        :return: port_map -> list of dictionaries with to values(external_port_id or internal_layer_id)
+        """
+        port_map = []
+        subgraph = if_node.then_graph if condition else if_node.else_graph
+        name_of_connection = 'input_id' if dir == 'in' else 'output_id'
+
+        for internal_node in subgraph.get_op_nodes():
+            if internal_node.has(name_of_connection):
+                port_map.append({'external_port_id': internal_node[name_of_connection],
+                                 'internal_layer_id': internal_node['internal_layer_id']})
+
+        return port_map
+
+    @staticmethod
+    def infer(if_node: Node):
+        If.update_body_parameters_shape(if_node, True)
+        If.update_body_parameters_shape(if_node, False)
+        partial_infer(if_node.then_graph)
+        partial_infer(if_node.else_graph)
+        If.update_if_output_ports_shape(if_node)
+
+    @staticmethod
+    def type_infer(if_node: Node):
+        from mo.middle.passes.infer import type_infer
+        If.update_body_parameters_type(if_node, True)
+        If.update_body_parameters_type(if_node, False)
+        type_infer(if_node.then_graph)
+        type_infer(if_node.else_graph)
+        If.update_if_output_ports_type(if_node)

model-optimizer/mo/front/tf/extractors/subgraph_utils.py

@@ -0,0 +1,108 @@
+# Copyright (C) 2018-2021 Intel Corporation
+# SPDX-License-Identifier: Apache-2.0
+
+import copy
+
+from extensions.ops.parameter import Parameter
+from mo.front.tf.extractor import tf_op_extractor, tf_op_extractors, create_tf_edge
+from mo.front.tf.extractors.utils import tf_dtype_extractor
+from mo.graph.graph import Graph, Node, add_opoutput
+from mo.ops.op import PermuteAttrs
+
+
+def update_body_graph(body_graph: Graph, subgraph_proto: dict,
+                      body_parameter_names: list, body_results: list):
+    """
+    Updates the loop body graph with a sub-graph (for body or condition functions)
+    :param body_graph: a loop body graph to be updated
+    :param subgraph_proto: a sub-graph in a protobuf format to be added into the loop body graph
+    :param body_parameter_names: a (unchanged) list of parameters in the loop body graph
+    :param body_results: a list of Result nodes that is extended with a list from a sub-graph
+    """
+    # create a map from a node name in original model to a name in a loop body graph assuming
+    # that names in the original model are unique
+    # initially, the map contains names for parameters that are common for the body and condition graphs
+    map_original_name = {}
+    for idx, pb_node in enumerate(subgraph_proto['input_arg']):
+        map_original_name[pb_node.name] = body_parameter_names[idx]
+
+    # walk through all nodes (non-parameter and non-result nodes) and add into the loop body graph
+    for pb_node in subgraph_proto['node_def']:
+        # create an NX node
+        id = body_graph.unique_id(pb_node.name)
+        map_original_name[pb_node.name] = id
+        body_graph.add_node(id, pb=pb_node, kind='op')
+        if hasattr(body_graph, 'op_names_statistic') and hasattr(pb_node, 'op'):
+            body_graph.op_names_statistic[pb_node.op] += 1
+
+        # add incoming edges based on data_nodes_map
+        for dst_port, inp in enumerate(pb_node.input):
+            orig_src_id = inp.split(":")[0]
+
+            # TODO: avoid this temporal workaround for TF 2.4 or higher RNN layers:
+            #  skip control flow dependency
+            if orig_src_id[0] == '^':
+                continue
+
+            src_id = map_original_name[orig_src_id]
+            src_port = 0 if len(inp.split(":")) == 1 else int(inp.split(":")[-1])
+            assert (body_graph.has_node(src_id))
+
+            body_graph.add_edges_from([create_tf_edge(src_id + ":" + str(src_port), id, dst_port)])
+
+    # create Result nodes in the loop body graph
+    for output in subgraph_proto['output_arg']:
+        output_name = subgraph_proto['ret'][output.name]
+        orig_src_id = output_name.split(":")[0]
+        src_id = map_original_name[orig_src_id]
+        src_port = 0 if len(output_name.split(":")) == 1 \
+            else int(output_name.split(":")[-1])
+        assert body_graph.has_node(src_id), 'The body graph does not contain output with name "{}"'.format(
+            src_id)
+        body_results.append(Node(body_graph, add_opoutput(body_graph, src_id, src_port, False)))
+
+    return True
+
+
+def get_graph_proto(external_graph: Graph, graph_id: str, node_with_graph: Node):
+    graph_name = node_with_graph.pb.attr[graph_id].func.name
+    node_name = node_with_graph.soft_get('name', node_with_graph.id)
+
+    assert 'library' in external_graph.graph, 'The graph does not contain a library that is required ' \
+                                              'by node with name "{}".'.format(node_name)
+
+    library_graph = external_graph.graph['library']
+
+    assert graph_name in library_graph, 'The library does not contain a function with name "{}" ' \
+                                        'that is required by node ' \
+                                        'with name "{}".'.format(graph_name, node_name)
+    return library_graph[graph_name]
+
+
+def create_internal_graph(external_graph: Graph):
+    internal_graph = Graph()
+    # fill the body graph
+    for attr_key in external_graph.graph.keys():
+        if attr_key != 'library':
+            internal_graph.graph[attr_key] = copy.deepcopy(external_graph.graph[attr_key])
+        else:
+            # it is sufficient to have a link to the library
+            internal_graph.graph['library'] = external_graph.graph['library']
+    return internal_graph
+
+
+def convert_graph_inputs_to_parameters(internal_graph, internal_graph_proto):
+    # create Parameter nodes for the body graph
+    body_parameters = []
+    body_parameter_names = []
+    for idx, pb_node in enumerate(internal_graph_proto['input_arg']):
+        param_id = internal_graph.unique_id(pb_node.name)
+        internal_graph.add_node(param_id, name=param_id, kind='op', op='Parameter', pb=None, shape=None)
+        parameter_node = Node(internal_graph, pb_node.name)
+        Parameter.update_node_stat(parameter_node,
+                                   {'data_type': tf_dtype_extractor(pb_node.type),
+                                    'permute_attrs': PermuteAttrs().update_attrs(attrs=[('shape', 'output:0')])}
+                                   )
+        body_parameters.append(parameter_node)
+        body_parameter_names.append(param_id)
+    return body_parameters, body_parameter_names

model-optimizer/mo/pipeline/common.py

@@ -194,7 +194,8 @@ def prepare_emit_ir(graph: Graph, data_type: str, output_dir: str, output_model_
     # do not run the type inference in sub-graphs. It will be called automatically as part of the type inference of
     # the TensorIterator nodes
     type_infer(graph)
-    RemoveUselessConvert().find_and_replace_pattern(graph)
+
+    for_graph_and_each_sub_graph_recursively(graph, RemoveUselessConvert().find_and_replace_pattern)
 
     ResultRename().find_and_replace_pattern(graph)
 

model-optimizer/mo/utils/ir_engine/ir_engine.py

@@ -240,34 +240,8 @@ class IREngine(object):
                 xml_body_child = list(layer.iterfind('body'))
                 assert len(xml_body_child) == 1
 
-                body_ir = IREngine(path_to_xml=None,
+                body_ir, input_port_map, output_port_map, input_layers = \
-                                   path_to_bin=self.path_to_bin,
+                    self.__read_subgraph(layer, layer_attrs, xml_body_child, 'port_map')
-                                   xml_tree=ElementTree(xml_body_child[0]))
-                self.graph.graph['hashes'].update(body_ir.graph.graph['hashes'])
-
-                # Find port_map section and take an input_port_map & output_port_map
-                xml_port_map = list(layer.iterfind('port_map'))
-                if not len(xml_port_map) == 1:
-                    log.warning("TensorIterator body won\'t be compared due to missing port_map section!")
-                    continue
-                xml_port_map = xml_port_map[0]
-
-                input_layers = []
-                input_port_map = []
-                output_port_map = []
-
-                for port in xml_port_map:
-                    if port.tag == 'input':
-                        if 'internal_layer_id' not in port.attrib:
-                            log.warning("internal_layer_id attrib not found in input section")
-                        else:
-                            input_layers.append(Node(body_ir.graph, port.attrib['internal_layer_id']))
-                            input_port_map.append(self.__normalize_attrs(port.attrib))
-                    elif port.tag == 'output':
-                        if 'internal_layer_id' not in port.attrib:
-                            log.warning("internal_layer_id attrib not found in output section")
-                        else:
-                            output_port_map.append(self.__normalize_attrs(port.attrib))
 
                 body_ir.input_node = input_layers[0]
                 layer_attrs.update({'body': body_ir})
@@ -287,6 +261,12 @@ class IREngine(object):
 
                 layer_attrs.update({'back_edges': back_edges})
 
+            elif attr.tag == 'then_body' or attr.tag == 'else_body':
+                assert layer.attrib['type'] == 'If', "Incorrect IR! The operation {0}" \
+                                                     " has sub-graphs for If operation"
+                layer_attrs = self.__read_if(layer, layer_attrs)
+                continue
+
         return layer_id, layer_attrs
 
     @staticmethod
@@ -405,3 +385,54 @@ class IREngine(object):
         if not isinstance(other, IREngine):
             raise AttributeError("IREngine can be compared only with IREngine object type")
         return self.compare(other)[0]
+
+    def __read_subgraph(self, layer, layer_attrs, body_child, port_map_name):
+        body_ir = IREngine(path_to_xml=None,
+                           path_to_bin=self.path_to_bin,
+                           xml_tree=ElementTree(body_child[0]))
+
+        self.graph.graph['hashes'].update(body_ir.graph.graph['hashes'])
+
+        xml_port_map = list(layer.iterfind(port_map_name))
+        assert not len(xml_port_map) != 1, "If then_body won\'t be compared due to missing {1} section in node {0}! " \
+            .format(layer_attrs['name'], port_map_name)
+        xml_port_map = xml_port_map[0]
+
+        input_layers = []
+        input_port_map = []
+        output_port_map = []
+
+        for port in xml_port_map:
+            if port.tag == 'input':
+                if 'internal_layer_id' not in port.attrib:
+                    log.warning("internal_layer_id attrib not found in input section")
+                else:
+                    input_layers.append(Node(body_ir.graph, port.attrib['internal_layer_id']))
+                    input_port_map.append(self.__normalize_attrs(port.attrib))
+            elif port.tag == 'output':
+                if 'internal_layer_id' not in port.attrib:
+                    log.warning("internal_layer_id attrib not found in output section")
+                else:
+                    output_port_map.append(self.__normalize_attrs(port.attrib))
+
+        return body_ir, input_port_map, output_port_map, input_layers
+
+    def __read_if(self, layer, layer_attrs):
+
+        xml_then_body_child = list(layer.iterfind('then_body'))
+        xml_else_body_child = list(layer.iterfind('else_body'))
+        assert len(xml_then_body_child) == 1 and len(xml_else_body_child) == 1, "If operation has only one subgraph"
+
+        then_body_ir, then_input_port_map, then_output_port_map, _ = \
+            self.__read_subgraph(layer, layer_attrs, xml_then_body_child, 'then_port_map')
+        layer_attrs.update({'then_graph': then_body_ir})
+        layer_attrs.update({'then_input_port_map': then_input_port_map})
+        layer_attrs.update({'then_output_port_map': then_output_port_map})
+
+        else_body_ir, else_input_port_map, else_output_port_map, _ = \
+            self.__read_subgraph(layer, layer_attrs, xml_else_body_child, 'else_port_map')
+        layer_attrs.update({'else_graph': else_body_ir})
+        layer_attrs.update({'else_input_port_map': else_input_port_map})
+        layer_attrs.update({'else_output_port_map': else_output_port_map})
+
+        return layer_attrs

model-optimizer/mo/utils/ir_reader/extenders/if_extender.py

@@ -0,0 +1,41 @@
+# Copyright (C) 2018-2021 Intel Corporation
+# SPDX-License-Identifier: Apache-2.0
+
+from mo.utils.graph import Node
+from mo.utils.ir_reader.extender import Extender
+from mo.utils.ir_reader.layer_to_class import copy_graph_with_ops
+
+
+class IfExtender(Extender):
+    op = 'If'
+
+    @staticmethod
+    def set_input_output_id(subgraph, input_port_map, output_port_map):
+        for node in subgraph.get_op_nodes():
+            if not node.has_valid('id'):
+                continue
+            node_id = int(node.soft_get('id'))
+            for if_input_mapping_elem in input_port_map:
+                if node_id == if_input_mapping_elem['internal_layer_id']:
+                    node['input_id'] = if_input_mapping_elem['external_port_id']
+            for if_out_mapping_elem in output_port_map:
+                if node_id == if_out_mapping_elem['internal_layer_id']:
+                    node['output_id'] = if_out_mapping_elem['external_port_id']
+
+    @staticmethod
+    def extend(op: Node):
+        assert op.has('then_graph'), 'There is no "then_body" attribute in the If op {}.'.format(op.name)
+        assert op.has('else_graph'), 'There is no "else_body" attribute in the If op {}.'.format(op.name)
+        # Now op.body is an IREngine, we need to replace it with IREngine.graph
+        op.then_graph.graph.graph['cmd_params'] = op.graph.graph['cmd_params']
+        op.then_graph.graph.graph['ir_version'] = op.graph.graph['ir_version']
+        op.then_graph.graph.name = op.name + '/then_body'
+
+        op.else_graph.graph.graph['cmd_params'] = op.graph.graph['cmd_params']
+        op.else_graph.graph.graph['ir_version'] = op.graph.graph['ir_version']
+        op.else_graph.graph.name = op.name + '/else_body'
+        op.then_graph = copy_graph_with_ops(op.then_graph.graph)
+        op.else_graph = copy_graph_with_ops(op.else_graph.graph)
+
+        IfExtender.set_input_output_id(op.then_graph, op.then_input_port_map, op.then_output_port_map)
+        IfExtender.set_input_output_id(op.else_graph, op.else_input_port_map, op.else_output_port_map)

model-optimizer/unit_tests/extensions/load/tf/loader_test.py

@@ -44,7 +44,7 @@ class TFLoaderTest(unittest.TestCase):
         # create fake Loop operation
         nodes = {
             **regular_op('input', {'op': 'Parameter'}),
-            **regular_op('loop', {'op': 'Loop', 'body': body_graph}),
+            **regular_op('loop', {'op': 'Loop', 'body': body_graph, 'sub_graphs': ['body']}),
             **result('result'),
         }
         edges = [*connect_front('input', '0:loop'),
@@ -65,4 +65,3 @@ class TFLoaderTest(unittest.TestCase):
 
     def test_no_convolution_main_and_sub_graph(self):
         self.assertFalse(graph_or_sub_graph_has_nhwc_ops(self.build_loop_graph(self.build_parameter_result_graph())))
-

model-optimizer/unit_tests/extensions/ops/If_test.py

@@ -0,0 +1,127 @@
+# Copyright (C) 2018-2021 Intel Corporation
+# SPDX-License-Identifier: Apache-2.0
+
+import numpy as np
+import numpy.testing as npt
+import unittest
+
+from extensions.ops.If import If
+from mo.ops.shape import Shape
+from extensions.ops.elementwise import Add, Mul
+from extensions.ops.identity import Identity
+from extensions.ops.parameter import Parameter
+from mo.front.common.partial_infer.concat import concat_infer
+from mo.front.common.partial_infer.utils import int64_array
+from mo.graph.graph import Node, Graph
+from mo.middle.passes.infer import partial_infer
+from mo.ops.concat import Concat
+from mo.ops.eltwise import eltwise_infer
+from mo.ops.result import Result
+from unit_tests.utils.graph import build_graph_with_edge_attrs, build_graph
+from unit_tests.utils.graph import regular_op_with_empty_data, connect, const, result, valued_const_with_data, \
+    regular_op, empty_data
+
+
+class TestIf(unittest.TestCase):
+    def test_simple_shape_inf(self):
+        then_graph_nodes = {**regular_op_with_empty_data('param_1', {'type': 'Parameter', 'kind': 'op', 'input_id': 1,
+                                                                     'shape': None, 'infer': Parameter.infer}),
+                            **regular_op_with_empty_data('param_2', {'type': 'Parameter', 'kind': 'op', 'input_id': 2,
+                                                                     'shape': None, 'infer': Parameter.infer}),
+                            **regular_op_with_empty_data('add', {'type': 'Add', 'kind': 'op', 'op': 'Add',
+                                                                 'infer': lambda node: eltwise_infer(node,
+                                                                                                     Add.operation)}),
+                            **regular_op_with_empty_data('mul', {'type': 'Mul', 'kind': 'op', 'op': 'Mul',
+                                                                 'infer': lambda node: eltwise_infer(node,
+                                                                                                     Mul.operation)}),
+                            **regular_op_with_empty_data('res1', {'kind': 'op', 'type': 'Result', 'op': 'Result',
+                                                                  'infer': lambda x: 0, 'output_id': 0}),
+                            **regular_op_with_empty_data('res2', {'kind': 'op', 'type': 'Result', 'op': 'Result',
+                                                                  'infer': lambda x: 0, 'output_id': 1})}
+        then_graph_edges = [*connect('param_1', '0:add'),
+                            *connect('param_2', '1:add'),
+                            *connect('param_1', '1:mul'),
+                            *connect('param_2', '0:mul'),
+                            *connect('add', 'res1'),
+                            *connect('mul', 'res2'),
+                            ]
+
+        else_graph_nodes = {**regular_op_with_empty_data('param_1', {'type': 'Parameter', 'kind': 'op', 'input_id': 1,
+                                                                     'shape': None, 'infer': Parameter.infer}),
+                            **regular_op_with_empty_data('param_2', {'type': 'Parameter', 'kind': 'op', 'input_id': 3,
+                                                                     'shape': None, 'infer': Parameter.infer}),
+                            **regular_op_with_empty_data('identity',
+                                                         {'kind': 'op', 'op': 'Identity', 'infer': Identity.infer}),
+                            **regular_op_with_empty_data('identity_1',
+                                                         {'kind': 'op', 'op': 'Identity', 'infer': Identity.infer}),
+                            **regular_op_with_empty_data('res1', {'kind': 'op', 'type': 'Result', 'op': 'Result',
+                                                                  'infer': lambda x: 0, 'output_id': 0}),
+                            **regular_op_with_empty_data('res2', {'kind': 'op', 'type': 'Result', 'op': 'Result',
+                                                                  'infer': lambda x: 0, 'output_id': 1})}
+        else_graph_edges = [*connect('param_1', 'identity'),
+                            *connect('param_2', 'identity_1'),
+                            *connect('identity_1', 'res2'),
+                            *connect('identity', 'res1'), ]
+        then_graph = build_graph_with_edge_attrs(then_graph_nodes, then_graph_edges)
+        else_graph = build_graph_with_edge_attrs(else_graph_nodes, else_graph_edges)
+        external_graph_nodes = {
+            **valued_const_with_data('cond', np.array([True], dtype=np.bool)),
+            **valued_const_with_data('input_2', int64_array([3, 2, 1])),
+            **valued_const_with_data('input_1', int64_array([1, 2, 3])),
+            **valued_const_with_data('input_3', int64_array([8, 4])),
+            **regular_op('if', {'kind': 'op', 'op': 'If', 'then_graph': then_graph,
+                                'else_graph': else_graph, 'infer': If.infer}),
+            **empty_data('if_d_1'),
+            **empty_data('if_d_2'),
+            **result('res_1'),
+            **result('res_2')}
+        external_graph_edges = [*connect('cond', '0:if'),
+                                *connect('input_1', '1:if'),
+                                *connect('input_2', '2:if'),
+                                *connect('input_3', '3:if'),
+                                ('if', 'if_d_1', {'out': 0}),
+                                ('if', 'if_d_2', {'out': 1}),
+                                ('if_d_1', 'res_1'),
+                                ('if_d_2', 'res_2')]
+
+        graph = build_graph(external_graph_nodes, external_graph_edges)
+        graph.stage = 'middle'
+        partial_infer(graph)
+        res_1 = Node(graph, 'res_1')
+        res_2 = Node(graph, 'res_2')
+        npt.assert_array_equal(res_1.in_port(0).data.get_shape(), int64_array([3]))
+        npt.assert_array_equal(res_2.in_port(0).data.get_shape(), int64_array([3]))
+
+    def test_fake_results(self):
+        then_graph_nodes = {**valued_const_with_data('fake_const', int64_array(0)),
+                            **regular_op_with_empty_data('shapeof',
+                                         {'kind': 'op', 'type': 'ShapeOf', 'op': 'ShapeOf', 'infer': Shape.infer,
+                                          'output_type': np.int64}),
+                            **regular_op_with_empty_data('res_1', {'kind': 'op', 'type': 'Result', 'op': 'Result',
+                                                                   'infer': lambda x: 0, 'output_id': 0})}
+        then_graph_edges = [*connect('fake_const', 'shapeof'),
+                            *connect('shapeof', 'res_1'),
+                            ]
+
+        else_graph_nodes = {**regular_op_with_empty_data('param_1', {'type': 'Parameter', 'kind': 'op', 'input_id': 1,
+                                                                     'shape': None, 'infer': Parameter.infer}),
+                            **regular_op_with_empty_data('res_1', {'kind': 'op', 'type': 'Result', 'op': 'Result',
+                                                                   'infer': lambda x: 0, 'output_id': 0})}
+        else_graph_edges = [*connect('param_1', 'res_1')]
+        then_graph = build_graph_with_edge_attrs(then_graph_nodes, then_graph_edges)
+        else_graph = build_graph_with_edge_attrs(else_graph_nodes, else_graph_edges)
+        external_graph_nodes = {
+            **valued_const_with_data('cond', np.array([True], dtype=np.bool)),
+            **valued_const_with_data('input_1', int64_array([[1, 2, 3], [3, 2, 3]])),
+            **regular_op_with_empty_data('if', {'kind': 'op', 'op': 'If', 'then_graph': then_graph,
+                                                'else_graph': else_graph, 'infer': If.infer}),
+            **result('res_1')}
+        external_graph_edges = [*connect('cond', '0:if'),
+                                *connect('input_1', '1:if'),
+                                *connect('if', 'res_1')]
+
+        graph = build_graph(external_graph_nodes, external_graph_edges)
+        graph.stage = 'middle'
+        partial_infer(graph)
+        res_1 = Node(graph, 'res_1')
+        npt.assert_array_equal(res_1.in_port(0).data.get_shape(), int64_array([2,3]))