src/core/NEON/kernels/arm_conv/depthwise/depthwise_implementation.hpp

/*
 * Copyright (c) 2021-2022 Arm Limited.
 *
 * SPDX-License-Identifier: MIT
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#pragma once

#include "depthwise.hpp"

#include <cstddef>
#include <functional>

using arm_gemm::Nothing;

namespace arm_conv {
namespace depthwise {

template <typename TInput, typename TWeight = TInput, typename TOutput = TInput, class OutputStage = Nothing>
struct DepthwiseImplementation
{
  const DepthwiseMethod method;
  const char *name;
  std::function<bool(const DepthwiseArgs &, const OutputStage &)> is_supported;
  std::function<uint64_t(const DepthwiseArgs &, const OutputStage &)> cycle_estimate;
  std::function<DepthwiseCommon<TInput, TWeight, TOutput> *(const DepthwiseArgs &, const OutputStage &)> initialise;

  bool get_is_supported(const DepthwiseArgs &args, const OutputStage &os) const
  {
    return (is_supported == nullptr) ? true : is_supported(args, os);
  }

  uint64_t get_cycle_estimate(const DepthwiseArgs &args, const OutputStage &os) const
  {
    return (cycle_estimate == nullptr) ? 0 : cycle_estimate(args, os);
  }

  DepthwiseCommon<TInput, TWeight, TOutput> *get_instance(const DepthwiseArgs &args, const OutputStage &os) const
  {
    return initialise(args, os);
  }
};

template <typename TInput, typename TWeight = TInput, typename TOutput = TInput, class OutputStage = Nothing>
const DepthwiseImplementation<TInput, TWeight, TOutput, OutputStage> *depthwise_implementation_list();

template <typename TInput, typename TWeight = TInput, typename TOutput = TInput, class OutputStage = Nothing>
bool find_implementation(
  const DepthwiseArgs &args,
  const OutputStage &os,
  const DepthwiseImplementation<TInput, TWeight, TOutput, OutputStage> * &selected
)
{
  selected = nullptr;
  uint64_t best_cycle_estimate = UINT64_MAX;

  const auto *impl = depthwise_implementation_list<TInput, TWeight, TOutput, OutputStage>();
  for (; impl->method != DepthwiseMethod::DEFAULT; impl++)
  {
    const bool has_cfg = (args.config != nullptr);
    const auto &cfg = args.config;

    if (
      !impl->get_is_supported(args, os) ||  // Problem is unsupported
      (has_cfg && cfg->method != DepthwiseMethod::DEFAULT && cfg->method != impl->method) ||
      (has_cfg && cfg->filter != "" && !std::strstr(impl->name, cfg->filter.c_str()))
    )
    {
      continue;
    }

    const auto cycle_estimate = impl->get_cycle_estimate(args, os);

    if (cycle_estimate == 0)
    {
      selected = impl;
      break;
    }

    if (selected == nullptr || cycle_estimate < best_cycle_estimate)
    {
      selected = impl;
      best_cycle_estimate = cycle_estimate;
    }
  }

  return (selected != nullptr);
}

template <typename TInput, typename TWeight, typename TOutput, class OutputStage>
std::vector<KernelDescription> get_compatible_kernels(const DepthwiseArgs &args, const OutputStage &os)
{
  std::vector<KernelDescription> kerns;

  // Find the default implementation so we can flag it accordingly
  const DepthwiseImplementation<TInput, TWeight, TOutput, OutputStage> *default_impl;
  find_implementation<TInput, TWeight, TOutput, OutputStage>(args, os, default_impl);

  for (auto impl = depthwise_implementation_list<TInput, TWeight, TOutput, OutputStage>();
       impl->method != DepthwiseMethod::DEFAULT; impl++)
  {
    if (!impl->get_is_supported(args, os))
    {
      continue;
    }

    kerns.emplace_back(
      impl->method, impl->name, impl == default_impl,
      impl->get_cycle_estimate(args, os)
    );
  }

  return kerns;
}

template <typename TInput, typename TWeight, typename TOutput, class OutputStage>
UniqueDepthwiseCommon<TInput, TWeight, TOutput> depthwise(const DepthwiseArgs &args, const OutputStage &os)
{
  const DepthwiseImplementation<TInput, TWeight, TOutput, OutputStage> *impl = nullptr;
  const bool success = find_implementation<TInput, TWeight, TOutput, OutputStage>(args, os, impl);
  return UniqueDepthwiseCommon<TInput, TWeight, TOutput>(success ? impl->get_instance(args, os) : nullptr);
}

}  // namespace depthwise
}  // namespace arm_conv