resize.h

// Copyright (c) 2025 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.

#pragma once

#include <ATen/core/Tensor.h>
#include <c10/core/TensorOptions.h>
#include <optional>
#include <string_view>

#include "paddle/phi/api/include/api.h"

namespace at {

// resize_ - use reshape for same-numel cases and set_ for storage-changing
// cases so repeated resize_ calls stay stable.
inline const at::Tensor& Tensor::resize_(
    at::IntArrayRef size,
    ::std::optional<at::MemoryFormat> memory_format) const {
  if (memory_format.has_value()) {
    TORCH_CHECK(*memory_format == at::MemoryFormat::Contiguous,
                "resize_ only supports contiguous memory format, but got ",
                static_cast<int>(*memory_format));
  }

  std::vector<int64_t> dims(size.begin(), size.end());
  int64_t new_numel = 1;
  for (auto dim : dims) {
    new_numel *= dim;
  }

  if (tensor_.numel() == new_numel) {
    const_cast<Tensor*>(this)->tensor_ =
        paddle::experimental::reshape(tensor_, phi::IntArray(dims));
    return *this;
  }

  auto source = tensor_.copy_to(tensor_.place(), /*blocking=*/true);
  paddle::experimental::set_(const_cast<Tensor*>(this)->tensor_, source, dims);
  return *this;
}

}  // namespace at