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1# pylint: disable=g-bad-file-header
2# Copyright 2015 The TensorFlow Authors. All Rights Reserved.
3#
4# Licensed under the Apache License, Version 2.0 (the "License");
5# you may not use this file except in compliance with the License.
6# You may obtain a copy of the License at
7#
8#     http://www.apache.org/licenses/LICENSE-2.0
9#
10# Unless required by applicable law or agreed to in writing, software
11# distributed under the License is distributed on an "AS IS" BASIS,
12# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13# See the License for the specific language governing permissions and
14# limitations under the License.
15# ==============================================================================
16"""Utilities to remove unneeded nodes from a GraphDefs."""
17
18import copy
19
20from google.protobuf import text_format
21
22from tensorflow.core.framework import attr_value_pb2
23from tensorflow.core.framework import graph_pb2
24from tensorflow.core.framework import node_def_pb2
25from tensorflow.python.framework import graph_util
26from tensorflow.python.platform import gfile
27
28
29def strip_unused(input_graph_def, input_node_names, output_node_names,
30                 placeholder_type_enum):
31  """Removes unused nodes from a GraphDef.
32
33  Args:
34    input_graph_def: A graph with nodes we want to prune.
35    input_node_names: A list of the nodes we use as inputs.
36    output_node_names: A list of the output nodes.
37    placeholder_type_enum: The AttrValue enum for the placeholder data type, or
38        a list that specifies one value per input node name.
39
40  Returns:
41    A `GraphDef` with all unnecessary ops removed.
42
43  Raises:
44    ValueError: If any element in `input_node_names` refers to a tensor instead
45      of an operation.
46    KeyError: If any element in `input_node_names` is not found in the graph.
47  """
48  for name in input_node_names:
49    if ":" in name:
50      raise ValueError(f"Name '{name}' appears to refer to a Tensor, not an "
51                       "Operation.")
52
53  # Here we replace the nodes we're going to override as inputs with
54  # placeholders so that any unused nodes that are inputs to them are
55  # automatically stripped out by extract_sub_graph().
56  not_found = {name for name in input_node_names}
57  inputs_replaced_graph_def = graph_pb2.GraphDef()
58  for node in input_graph_def.node:
59    if node.name in input_node_names:
60      not_found.remove(node.name)
61      placeholder_node = node_def_pb2.NodeDef()
62      placeholder_node.op = "Placeholder"
63      placeholder_node.name = node.name
64      if isinstance(placeholder_type_enum, list):
65        input_node_index = input_node_names.index(node.name)
66        placeholder_node.attr["dtype"].CopyFrom(
67            attr_value_pb2.AttrValue(type=placeholder_type_enum[
68                input_node_index]))
69      else:
70        placeholder_node.attr["dtype"].CopyFrom(
71            attr_value_pb2.AttrValue(type=placeholder_type_enum))
72      if "_output_shapes" in node.attr:
73        placeholder_node.attr["_output_shapes"].CopyFrom(node.attr[
74            "_output_shapes"])
75      if "shape" in node.attr:
76        placeholder_node.attr["shape"].CopyFrom(node.attr["shape"])
77      inputs_replaced_graph_def.node.extend([placeholder_node])
78    else:
79      inputs_replaced_graph_def.node.extend([copy.deepcopy(node)])
80
81  if not_found:
82    raise KeyError(f"The following input nodes were not found: {not_found}.")
83
84  output_graph_def = graph_util.extract_sub_graph(inputs_replaced_graph_def,
85                                                  output_node_names)
86  return output_graph_def
87
88
89def strip_unused_from_files(input_graph, input_binary, output_graph,
90                            output_binary, input_node_names, output_node_names,
91                            placeholder_type_enum):
92  """Removes unused nodes from a graph file."""
93
94  if not gfile.Exists(input_graph):
95    print("Input graph file '" + input_graph + "' does not exist!")
96    return -1
97
98  if not output_node_names:
99    print("You need to supply the name of a node to --output_node_names.")
100    return -1
101
102  input_graph_def = graph_pb2.GraphDef()
103  mode = "rb" if input_binary else "r"
104  with gfile.GFile(input_graph, mode) as f:
105    if input_binary:
106      input_graph_def.ParseFromString(f.read())
107    else:
108      text_format.Merge(f.read(), input_graph_def)
109
110  output_graph_def = strip_unused(input_graph_def,
111                                  input_node_names.split(","),
112                                  output_node_names.split(","),
113                                  placeholder_type_enum)
114
115  if output_binary:
116    with gfile.GFile(output_graph, "wb") as f:
117      f.write(output_graph_def.SerializeToString())
118  else:
119    with gfile.GFile(output_graph, "w") as f:
120      f.write(text_format.MessageToString(output_graph_def))
121  print("%d ops in the final graph." % len(output_graph_def.node))
122