/* Copyright 2015 The TensorFlow Authors. All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    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,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
==============================================================================*/

#include "tensorflow/core/kernels/pooling_ops_common.h"

#include <vector>
#include "tensorflow/core/common_runtime/device.h"
#include "tensorflow/core/framework/tensor.h"

#if GOOGLE_CUDA
#include "tensorflow/core/kernels/conv_2d.h"
#include "tensorflow/core/kernels/maxpooling_op_gpu.h"
#include "tensorflow/core/kernels/pooling_ops_common_gpu.h"
#include "tensorflow/core/platform/stream_executor.h"
#endif  // GOOGLE_CUDA

namespace tensorflow {

PoolParameters::PoolParameters(OpKernelContext* context,
                               const std::vector<int32>& ksize,
                               const std::vector<int32>& stride,
                               Padding padding, TensorFormat data_format,
                               const TensorShape& tensor_in_shape) {
  // For maxpooling, tensor_in should have 4 dimensions.
  OP_REQUIRES(context, tensor_in_shape.dims() == 4,
              errors::InvalidArgument("tensor_in must be 4-dimensional"));

  this->data_format = data_format;
  depth = GetTensorDim(tensor_in_shape, data_format, 'C');
  tensor_in_cols = GetTensorDim(tensor_in_shape, data_format, 'W');
  tensor_in_rows = GetTensorDim(tensor_in_shape, data_format, 'H');
  tensor_in_batch = GetTensorDim(tensor_in_shape, data_format, 'N');
  window_rows = GetTensorDim(ksize, data_format, 'H');
  window_cols = GetTensorDim(ksize, data_format, 'W');
  depth_window = GetTensorDim(ksize, data_format, 'C');
  row_stride = GetTensorDim(stride, data_format, 'H');
  col_stride = GetTensorDim(stride, data_format, 'W');
  depth_stride = GetTensorDim(stride, data_format, 'C');

  // We only support 2D pooling across width/height and depthwise
  // pooling, not a combination.
  OP_REQUIRES(context,
              (depth_window == 1 || (window_rows == 1 && window_cols == 1)),
              errors::Unimplemented(
                  "MaxPooling supports exactly one of pooling across depth "
                  "or pooling across width/height."));

  if (depth_window == 1) {
    OP_REQUIRES_OK(
        context, GetWindowedOutputSize(tensor_in_rows, window_rows, row_stride,
                                       padding, &out_height, &pad_rows));
    OP_REQUIRES_OK(
        context, GetWindowedOutputSize(tensor_in_cols, window_cols, col_stride,
                                       padding, &out_width, &pad_cols));
  } else {
    // Our current version of depthwise max pooling does not support
    // any padding, and expects the depth_window to equal the
    // depth_stride (no overlapping).
    OP_REQUIRES(
        context, depth % depth_window == 0,
        errors::Unimplemented("Depthwise max pooling requires the depth "
                              "window to evenly divide the input depth"));
    OP_REQUIRES(
        context, depth_stride == depth_window,
        errors::Unimplemented("Depthwise max pooling requires the depth "
                              "window to equal the depth stride"));

    // The current version of depthwise max is only implemented on CPU.
    OP_REQUIRES(context,
                (DeviceType(static_cast<Device*>(context->device())
                                ->attributes()
                                .device_type()) == DeviceType(DEVICE_CPU)),
                errors::Unimplemented("Depthwise max pooling is currently "
                                      "only implemented for CPU devices."));

    pad_depth = 0;
    out_depth = depth / depth_window;
  }
}

TensorShape PoolParameters::forward_output_shape() {
  if (depth_window == 1) {
    // Spatial pooling
    return ShapeFromFormat(data_format, tensor_in_batch, out_height, out_width,
                           depth);
  } else {
    // Depthwise pooling
    return TensorShape(
        {tensor_in_batch, tensor_in_rows, tensor_in_cols, out_depth});
  }
}

#ifdef GOOGLE_CUDA

namespace {
template <typename T>
perftools::gputools::DeviceMemory<T> AsDeviceMemory(const T* cuda_memory,
                                                    uint64 size) {
  perftools::gputools::DeviceMemoryBase wrapped(const_cast<T*>(cuda_memory),
                                                size * sizeof(T));
  perftools::gputools::DeviceMemory<T> typed(wrapped);
  return typed;
}
}  // namespace

// Forward declarations of the functor specializations for GPU.
namespace functor {
#define DECLARE_GPU_SPEC(T)                                         \
  template <>                                                       \
  void TransformDepth<GPUDevice, T, Eigen::DenseIndex>::operator()( \
      const GPUDevice& d, typename TTypes<T, 4>::ConstTensor in,    \
      const Eigen::DSizes<Eigen::DenseIndex, 4>& shuffle,           \
      typename TTypes<T, 4>::Tensor out);                           \
  extern template struct TransformDepth<GPUDevice, T, Eigen::DenseIndex>;

DECLARE_GPU_SPEC(float);
DECLARE_GPU_SPEC(Eigen::half);
#undef DECLARE_GPU_SPEC
}  // namespace functor

template <typename T>
void DnnPoolingOp<T>::Compute(
    OpKernelContext* context,
    perftools::gputools::dnn::PoolingMode pooling_mode,
    const std::vector<int32>& size, const std::vector<int32>& stride,
    Padding padding, TensorFormat data_format, const Tensor& tensor_in,
    const TensorShape& tensor_out_shape) {
  Tensor* tensor_out = nullptr;
  OP_REQUIRES_OK(context,
                 context->allocate_output(0, tensor_out_shape, &tensor_out));

  PoolParameters params{context, size,        stride,
                        padding, data_format, tensor_in.shape()};
  if (!context->status().ok()) {
    return;
  }

  /// For now, cudnn does not support NHWC format, so we need to convert it
  /// to NCHW before calling cudnn. We need to get rid of this once it is done
  Tensor transformed_input;
  if (data_format == FORMAT_NHWC) {
    OP_REQUIRES_OK(context, context->allocate_temp(
                                DataTypeToEnum<T>::value,
                                ShapeFromFormat(FORMAT_NCHW, tensor_in.shape(),
                                                data_format),
                                &transformed_input));
    functor::NHWCToNCHW<GPUDevice, T, 4>()(context->eigen_device<Device>(),
                                           tensor_in.tensor<T, 4>(),
                                           transformed_input.tensor<T, 4>());
  } else {
    transformed_input = tensor_in;
  }
  Tensor transformed_output;
  if (data_format == FORMAT_NHWC) {
    OP_REQUIRES_OK(context, context->allocate_temp(
                                DataTypeToEnum<T>::value,
                                ShapeFromFormat(FORMAT_NCHW, tensor_out_shape,
                                                data_format),
                                &transformed_output));
  } else {
    transformed_output = *tensor_out;
  }

  /// Get ready to call cudnn
  perftools::gputools::dnn::PoolingDescriptor pooling_desc;
  pooling_desc.set_pooling_mode(pooling_mode)
      .set_window_height(params.window_rows)
      .set_window_width(params.window_cols)
      .set_vertical_stride(params.row_stride)
      .set_horizontal_stride(params.col_stride)
      .set_vertical_padding(params.pad_rows)
      .set_horizontal_padding(params.pad_cols);

  perftools::gputools::dnn::BatchDescriptor input_desc;
  input_desc.set_count(params.tensor_in_batch)
      .set_height(params.tensor_in_rows)
      .set_width(params.tensor_in_cols)
      .set_feature_map_count(params.depth)
      .set_layout(perftools::gputools::dnn::DataLayout::kBatchDepthYX);

  perftools::gputools::dnn::BatchDescriptor output_desc;
  output_desc.set_count(params.tensor_in_batch)
      .set_height(params.out_height)
      .set_width(params.out_width)
      .set_feature_map_count(params.depth)
      .set_layout(perftools::gputools::dnn::DataLayout::kBatchDepthYX);

  auto input_data = AsDeviceMemory(transformed_input.template flat<T>().data(),
                                   transformed_input.template flat<T>().size());
  auto output_data =
      AsDeviceMemory(transformed_output.template flat<T>().data(),
                     transformed_output.template flat<T>().size());

  auto* stream = context->op_device_context()->stream();
  OP_REQUIRES(context, stream, errors::Internal("No GPU stream available."));

  bool status = stream
                    ->ThenPoolForward(pooling_desc, input_desc, input_data,
                                      output_desc, &output_data)
                    .ok();
  OP_REQUIRES(context, status,
              errors::Internal("cudnn PoolBackward launch failed"));

  if (data_format == FORMAT_NHWC) {
    /// Transform the output data from NCHW back to NHWC
    auto toConstTensor = [](const Tensor& x) -> const Tensor { return x; };
    functor::NCHWToNHWC<GPUDevice, T, 4>()(
        context->eigen_device<Device>(),
        toConstTensor(transformed_output).template tensor<T, 4>(),
        tensor_out->tensor<T, 4>());
  }
}

template <typename T>
void DnnPoolingGradOp<T>::Compute(
    OpKernelContext* context,
    perftools::gputools::dnn::PoolingMode pooling_mode,
    const std::vector<int32>& size, const std::vector<int32>& stride,
    Padding padding, TensorFormat data_format, const Tensor* tensor_in,
    const Tensor* tensor_out, const Tensor& out_backprop,
    const TensorShape& tensor_in_shape) {
  CHECK((pooling_mode != perftools::gputools::dnn::PoolingMode::kMaximum) ||
        (tensor_in && tensor_out))
      << "For MaxPoolGrad, both tensor_in and tensor_out needs to be "
         "specified";

  Tensor* input_backprop = nullptr;
  OP_REQUIRES_OK(context,
                 context->allocate_output(0, tensor_in_shape, &input_backprop));

  PoolParameters params{context, size,        stride,
                        padding, data_format, tensor_in_shape};
  if (!context->status().ok()) {
    return;
  }

  /// For now, cudnn does not support NHWC format, so we need to convert it
  /// to NCHW before calling cudnn. We need to get rid of this once it is done
  Tensor transformed_input;
  TensorShape transformed_input_shape;
  if (data_format == FORMAT_NHWC || !tensor_in) {
    transformed_input_shape =
        ShapeFromFormat(FORMAT_NCHW, tensor_in_shape, data_format);
    OP_REQUIRES_OK(context, context->allocate_temp(DataTypeToEnum<T>::value,
                                                   transformed_input_shape,
                                                   &transformed_input));
  } else {
    transformed_input = *tensor_in;
  }
  Tensor transformed_output;
  TensorShape transformed_output_shape;
  if (data_format == FORMAT_NHWC || !tensor_out) {
    transformed_output_shape =
        ShapeFromFormat(FORMAT_NCHW, out_backprop.shape(), data_format);
    OP_REQUIRES_OK(context, context->allocate_temp(DataTypeToEnum<T>::value,
                                                   transformed_output_shape,
                                                   &transformed_output));
  } else {
    transformed_output = *tensor_out;
  }
  Tensor transformed_input_backprop;
  if (data_format == FORMAT_NHWC) {
    OP_REQUIRES_OK(context,
                   context->allocate_temp(DataTypeToEnum<T>::value,
                                          transformed_input_shape,
                                          &transformed_input_backprop));
  } else {
    transformed_input_backprop = *input_backprop;
  }
  Tensor transformed_output_backprop;
  if (data_format == FORMAT_NHWC) {
    OP_REQUIRES_OK(context,
                   context->allocate_temp(DataTypeToEnum<T>::value,
                                          transformed_output_shape,
                                          &transformed_output_backprop));
  } else {
    transformed_output_backprop = out_backprop;
  }

  if (data_format == FORMAT_NHWC) {
    /// Convert the data from NHWC to NCHW if necessary.
    if (tensor_in) {
      // For AvgPoolGrad, the original input tensor is not necessary. However,
      // cudnn still requires them to run, although they do not affect the
      // results.
      functor::NHWCToNCHW<GPUDevice, T, 4>()(context->eigen_device<Device>(),
                                             tensor_in->tensor<T, 4>(),
                                             transformed_input.tensor<T, 4>());
    }
    if (tensor_out) {
      // For AvgPoolGrad, the original output tensor is not necessary. However,
      // cudnn still requires them to run, although they do not affect the
      // results.
      functor::NHWCToNCHW<GPUDevice, T, 4>()(context->eigen_device<Device>(),
                                             tensor_out->tensor<T, 4>(),
                                             transformed_output.tensor<T, 4>());
    }
    functor::NHWCToNCHW<GPUDevice, T, 4>()(
        context->eigen_device<Device>(), out_backprop.tensor<T, 4>(),
        transformed_output_backprop.tensor<T, 4>());
  }

  /// Get ready to call cudnn
  perftools::gputools::dnn::PoolingDescriptor pooling_desc;
  pooling_desc.set_pooling_mode(pooling_mode)
      .set_window_height(params.window_rows)
      .set_window_width(params.window_cols)
      .set_vertical_stride(params.row_stride)
      .set_horizontal_stride(params.col_stride)
      .set_vertical_padding(params.pad_rows)
      .set_horizontal_padding(params.pad_cols);

  perftools::gputools::dnn::BatchDescriptor orig_output_desc;
  orig_output_desc.set_count(params.tensor_in_batch)
      .set_height(params.out_height)
      .set_width(params.out_width)
      .set_feature_map_count(params.depth)
      .set_layout(perftools::gputools::dnn::DataLayout::kBatchDepthYX);

  perftools::gputools::dnn::BatchDescriptor orig_input_desc;
  orig_input_desc.set_count(params.tensor_in_batch)
      .set_height(params.tensor_in_rows)
      .set_width(params.tensor_in_cols)
      .set_feature_map_count(params.depth)
      .set_layout(perftools::gputools::dnn::DataLayout::kBatchDepthYX);

  auto orig_output_data =
      AsDeviceMemory(transformed_output.template flat<T>().data(),
                     transformed_output.template flat<T>().size());
  auto orig_input_data =
      AsDeviceMemory(transformed_input.template flat<T>().data(),
                     transformed_input.template flat<T>().size());
  auto output_backprop_data =
      AsDeviceMemory(transformed_output_backprop.template flat<T>().data(),
                     transformed_output_backprop.template flat<T>().size());
  auto input_backprop_data =
      AsDeviceMemory(transformed_input_backprop.template flat<T>().data(),
                     transformed_input_backprop.template flat<T>().size());

  auto* stream = context->op_device_context()->stream();
  OP_REQUIRES(context, stream, errors::Internal("No GPU stream available."));

  bool status =
      stream
          ->ThenPoolBackward(pooling_desc, orig_input_desc, orig_input_data,
                             orig_output_desc, orig_output_data,
                             output_backprop_data, &input_backprop_data)
          .ok();
  OP_REQUIRES(context, status,
              errors::Internal("cudnn PoolBackward launch failed"));

  if (data_format == FORMAT_NHWC) {
    /// Transform the output data from NCHW back to NHWC.
    auto toConstTensor = [](const Tensor& x) -> const Tensor { return x; };
    functor::NCHWToNHWC<GPUDevice, T, 4>()(
        context->eigen_device<Device>(),
        toConstTensor(transformed_input_backprop).template tensor<T, 4>(),
        input_backprop->tensor<T, 4>());
  }
}

template class DnnPoolingOp<Eigen::half>;
template class DnnPoolingOp<float>;
template class DnnPoolingGradOp<Eigen::half>;
template class DnnPoolingGradOp<float>;

#endif  // GOOGLE_CUDA

}  // namespace tensorflow
