EVOLUTION-MANAGER

Edit File: shape_inference_helpers.h

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
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http://www.apache.org/licenses/LICENSE-2.0

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==============================================================================*/

#ifndef TENSORFLOW_COMPILER_JIT_SHAPE_INFERENCE_HELPERS_H_
#define TENSORFLOW_COMPILER_JIT_SHAPE_INFERENCE_HELPERS_H_

#include <vector>

#include "tensorflow/core/graph/graph.h"

namespace tensorflow {

// Helper class to temporarily remove, then replace, the back edges in a
// graph. Simple algorithms for shape inference don't work with cycles, and this
// class can be used to remove cycles before running inference and replace them
// after. Correct usage requires exactly one call to Remove(), followed by any
// number of calls to RemovedEdges() and at most one call to Replace(). The call
// to Replace() is optional if the graph will be discarded without being
// executed, e.g., if it is being used purely for a shape inference pass.
class BackEdgeHelper {
 public:
  struct BackEdge {
    const Edge* edge;
    Node* src;
    int src_output;
    Node* dst;
    int dst_input;
  };

BackEdgeHelper() = default;
  // Disallows copy and assign.
  BackEdgeHelper(const BackEdgeHelper& other) = delete;
  BackEdgeHelper& operator=(const BackEdgeHelper& other) = delete;

// Temporarily removes all the back edges in graph.
  Status Remove(Graph* graph);

// Gets the list of removed edges.
  const std::vector<BackEdge>& RemovedEdges() const;

// Replaces the back edges removed by a prior call to Remove.
  Status Replace();

private:
  Graph* graph_ = nullptr;  // not owned
  std::vector<BackEdge> back_edges_;
  // Set once Replace has been called.
  bool replaced_ = false;
};

}  // namespace tensorflow

#endif  // TENSORFLOW_COMPILER_JIT_SHAPE_INFERENCE_HELPERS_H_