EVOLUTION-MANAGER

Edit File: xla_tensor.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

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
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==============================================================================*/

#ifndef TENSORFLOW_COMPILER_JIT_XLA_TENSOR_H_
#define TENSORFLOW_COMPILER_JIT_XLA_TENSOR_H_

#include <memory>

#include "absl/memory/memory.h"
#include "tensorflow/compiler/xla/client/local_client.h"
#include "tensorflow/compiler/xla/service/shaped_buffer.h"
#include "tensorflow/core/framework/allocator.h"
#include "tensorflow/core/framework/device_base.h"
#include "tensorflow/core/lib/core/status.h"
#include "tensorflow/core/platform/mutex.h"

namespace tensorflow {

// The implementation of a Tensor for an XlaDevice. All device tensors are
// actually one of these.
//
// To distinguish between "normal" device tensors and XlaTensors, the raw
// pointer data stored in the TensorBuffer is a tagged pointer.
class XlaTensor {
 public:
  // Downcast from a Tensor to an XlaTensor. Return nullptr if the downcast
  // fails.
  static XlaTensor* FromTensor(const Tensor* tensor);

// Create a DeviceMemoryBase from a Tensor. The Tensor can be an XlaTensor, in
  // which case the returned value is shaped_buffer()->root_buffer(), or a
  // normal Tensor in which case the returned value is
  // {tensor.tensor_data().data(), tensor.tensor_data().size}.
  static se::DeviceMemoryBase DeviceMemoryFromTensor(const Tensor& tensor);

// Assign the internal ShapedBuffer to new memory for the given dtype and
  // shape. If a ShapedBuffer exists already (has_shaped_buffer() == true), it
  // is replaced and the managed memory deallocated.
  Status AllocateShapedBuffer(DataType dtype, const xla::Shape& on_host_shape,
                              xla::LocalClient* client, int device_ordinal);

// Some Tensors can have complex on-device shapes, including tuple shapes. To
  // manage the memory for these tensors a ShapedBuffer may be required.

// Return true if this XlaTensor contains a ShapedBuffer.
  bool has_shaped_buffer() const { return shaped_buffer_.has_value(); }
  // Return the contained ShapedBuffer.
  // REQUIRES: has_shaped_buffer()
  const xla::ShapedBuffer& shaped_buffer() const {
    CHECK(has_shaped_buffer());
    return *shaped_buffer_;
  }
  xla::ShapedBuffer& shaped_buffer() {
    CHECK(has_shaped_buffer());
    return *shaped_buffer_;
  }
  // Mutates the XlaTensor to set the ShapedBuffer.
  void set_shaped_buffer(xla::ScopedShapedBuffer shaped_buffer) {
    shaped_buffer_ = std::move(shaped_buffer);
  }

// Adds synchronization events to 'stream' that wait for this tensor to be
  // defined on 'stream'. Does nothing if the tensor is already defined on that
  // stream.
  void WaitForDefinitionEventOnStream(se::Stream* stream);

// (Re)sets the definition event of the tensor to 'event', and promises that
  // the tensor has already been defined on stream. Removes any previous
  // definition event or any previous promises about the tensor being defined on
  // streams.
  // It is legal to reset the definition event of a tensor when overwriting the
  // tensor's value (at which point, it is effectively a new tensor once again.)
  void ResetDefinitionEvent(std::shared_ptr<se::Event> event,
                            se::Stream* stream);

// Refresh the status of streams_defined_on_. Return the first not-OK stream's
  // status or OK.
  Status RefreshStatusOfStreams();

// Convert from a raw pointer to an XlaTensor, removing the pointer tag.
  static XlaTensor* FromOpaquePointer(void* ptr);
  // Convert to a raw pointer from an XlaTensor, adding the pointer tag.
  static void* ToOpaquePointer(XlaTensor* tensor);

private:
  // The optional contained ShapedBuffer.
  absl::optional<xla::ScopedShapedBuffer> shaped_buffer_;
  // An optional host tensor value.
  absl::optional<Tensor> host_tensor_;
  // An optional event that is triggered when the tensor's content has been
  // defined. If this event is nullptr, it is assumed that the tensor's content
  // is always defined.
  std::shared_ptr<se::Event> definition_event_;
  // A list of all streams for which the tensor's content is defined for any
  // newly enqueued command.
  absl::InlinedVector<se::Stream*, 2> streams_defined_on_ TF_GUARDED_BY(mu_);
  mutex mu_;
};

}  // namespace tensorflow

#endif  // TENSORFLOW_COMPILER_JIT_XLA_TENSOR_H_