1/**
2 * Copyright (c) Glow Contributors. See CONTRIBUTORS file.
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#ifndef GLOW_GRAPH_GRAD_H
17#define GLOW_GRAPH_GRAD_H
18
19#include "glow/Graph/Node.h"
20
21#include <unordered_map>
22
23namespace glow {
24
25class Function;
26
27/// A Helper class that manages the mapping between gradients and activations,
28/// and helps to accumulate gradients into placeholders.
29class GraphGradMapper {
30 /// The graph that we mutate.
31 Function *F_;
32 /// Maps activation values to their gradient values.
33 std::unordered_map<NodeValue, NodeValue> map_;
34
35public:
36 GraphGradMapper(Function *F) : F_(F) {}
37
38 /// \register the node \p grad as the grad of \p activation. If the node is
39 /// already registered then create an 'add' node that accumulates the gradient
40 /// into the grad buffer.
41 void addGradient(NodeValue activation, NodeValue grad);
42
43 /// \returns the node that \p activation is mapped to.
44 NodeValue getGradient(NodeValue activation);
45
46 /// \returns True if the node \p activation is mapped.
47 bool hasGradient(NodeValue activation);
48};
49
50} // namespace glow
51
52#endif // GLOW_GRAPH_GRAD_H
53