1 | /* Copyright 2016 The TensorFlow Authors. All Rights Reserved. |
2 | |
3 | Licensed under the Apache License, Version 2.0 (the "License"); |
4 | you may not use this file except in compliance with the License. |
5 | You may obtain a copy of the License at |
6 | |
7 | http://www.apache.org/licenses/LICENSE-2.0 |
8 | |
9 | Unless required by applicable law or agreed to in writing, software |
10 | distributed under the License is distributed on an "AS IS" BASIS, |
11 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
12 | See the License for the specific language governing permissions and |
13 | limitations under the License. |
14 | ==============================================================================*/ |
15 | |
16 | #ifndef TENSORFLOW_CORE_GRAPH_CONTROL_FLOW_H_ |
17 | #define TENSORFLOW_CORE_GRAPH_CONTROL_FLOW_H_ |
18 | |
19 | #include <vector> |
20 | |
21 | #include "tensorflow/core/graph/graph.h" |
22 | #include "tensorflow/core/lib/core/status.h" |
23 | |
24 | namespace tensorflow { |
25 | |
26 | // Control flow info for a graph node. |
27 | struct ControlFlowInfo { |
28 | // 'frame' and 'parent_frame' are pointers to: |
29 | // |
30 | // a) One of the Enter nodes corresponding to the loop body, if the node |
31 | // executes inside a loop. If multiple tensors enter the while loop, it's |
32 | // undefined which Enter node will be used. |
33 | // |
34 | // b) SOURCE node (node.id() == Graph::kSourceId), if the node is not inside |
35 | // any of the while loops. |
36 | |
37 | const Node* frame = nullptr; // frame of a node |
38 | const Node* parent_frame = nullptr; // parent frame of a node |
39 | string frame_name; // frame name of a node |
40 | }; |
41 | |
42 | // Clear and populate `info` with each node's frame and the level it belongs to. |
43 | // We check the well-formedness of the graph: |
44 | // 1) All inputs to a node must come from the same frame and have the same |
45 | // "static" iteration level. |
46 | // 2) Each frame has at most one LoopCond node. |
47 | // 3) Each frame has a single parent frame. |
48 | // If `unreachable_nodes` is set, return names of nodes unreachable from the |
49 | // source node. We cannot build ControlFlowInfo for such nodes. They might be |
50 | // pruned later. |
51 | // |
52 | // NOTE(yuanbyu): For now, we require all sends/recvs have iteration level 0. |
53 | // This essentially means there can't be multiple serial Nexts in an iteration, |
54 | // which all sane front-ends should satisfy. |
55 | Status BuildControlFlowInfo(const Graph* g, std::vector<ControlFlowInfo>* info, |
56 | std::vector<string>* unreachable_nodes = nullptr); |
57 | |
58 | } // namespace tensorflow |
59 | |
60 | #endif // TENSORFLOW_CORE_GRAPH_CONTROL_FLOW_H_ |
61 | |