// Copyright (c) 2022 PaddlePaddle 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 "paddle/phi/kernels/cast_kernel.h"

#include "paddle/phi/backends/onednn/onednn_reuse.h"
#include "paddle/phi/core/kernel_registry.h"

namespace phi {

bool CastCheckIfOneDNNSupport(const KernelContext* dev_ctx) {
  if ((dev_ctx->InputAt<DenseTensor>(0).dtype() != DataType::FLOAT32 &&
       dev_ctx->InputAt<DenseTensor>(0).dtype() != DataType::BFLOAT16) ||
      (dev_ctx->AttrAt<DataType>(0) != DataType::FLOAT32 &&
       dev_ctx->AttrAt<DataType>(0) != DataType::BFLOAT16)) {
    return false;
  }
  return true;
}

template <typename T, typename Context>
void CastKernel(const Context& dev_ctx,
                const DenseTensor& x,
                DataType out_dtype,
                DenseTensor* out) {
  // Should keep eye on it, since it may hide some issue action like meaningless
  // cast (intended to transfer but due to some reason appear to be cast between
  // same dtype)
  if (x.dtype() == out_dtype) {
    if (!out->IsSharedWith(x)) {
      phi::Copy(dev_ctx, x, dev_ctx.GetPlace(), false, out);
      out->set_lod(x.lod());
      out->set_mem_desc(x.mem_desc());
    }
    return;
  }

  DataType in_dtype = x.dtype();

  dnnl::memory::data_type in_dnnl_dtype = funcs::ToOneDNNDataType(in_dtype);
  dnnl::memory::data_type out_dnnl_dtype = funcs::ToOneDNNDataType(out_dtype);

  auto x_tz = vectorize(x.dims());

  funcs::ReorderOneDNNHandler reorder_handler(x_tz,
                                              in_dtype,
                                              in_dnnl_dtype,
                                              out_dtype,
                                              out_dnnl_dtype,
                                              dev_ctx.GetEngine());

  auto reorder_src_memory_p = reorder_handler.AcquireSrcMemory(
      x.mem_desc(), funcs::to_void_cast(x.data<T>()));
  auto reorder_dst_memory_p =
      reorder_handler.AcquireDstMemory(out, x.mem_desc(), dev_ctx.GetPlace());
  auto reorder_p = reorder_handler.AcquireReorder(reorder_dst_memory_p,
                                                  reorder_src_memory_p);

  auto& astream = OneDNNContext::tls().get_stream();
  reorder_p->execute(astream, *reorder_src_memory_p, *reorder_dst_memory_p);
  astream.wait();

  out->set_layout(DataLayout::ONEDNN);
  out->set_mem_desc(reorder_dst_memory_p->get_desc());
}

}  // namespace phi

PD_REGISTER_KERNEL(
    cast, OneDNN, ONEDNN, phi::CastKernel, float, phi::bfloat16) {
  kernel->check_if_onednn_kernel_support_ = phi::CastCheckIfOneDNNSupport;
}