Function ComputeStride

oneflow/core/functional/impl/common.cpp:207–252

}

Optional<Stride> ComputeStride(const Shape& shape, const Stride& stride,
                               const Shape& target_shape) {
  /*************************************************
   * Description: in some case, view operate is not allowed, so need to check it's validation,
   * the check refers to torch(aten/src/ATen/native/TensorShape.cpp)
   *************************************************/
  if (stride.size() == 0) {
    // for scalar input tensor
    return Stride(target_shape.NumAxes(), 1);
  }
  int64_t elem_count = shape.elem_cnt();
  int64_t ndim = shape.NumAxes();
  int64_t tgt_ndim = target_shape.NumAxes();
  DimVector shape_vec = shape.dim_vec();
  DimVector tgt_shape_vec = target_shape.dim_vec();
  if (elem_count == 0) { return NullOpt; }

  int64_t view_d = tgt_ndim - 1;
  int64_t chunk_base_stride = stride.back();
  Stride target_stride(tgt_ndim);
  // stride for each subspace in the chunk
  // numel in current chunk
  int64_t tensor_numel = 1;
  int64_t view_numel = 1;
  for (int64_t tensor_d = ndim - 1; tensor_d >= 0; tensor_d--) {
    tensor_numel *= shape_vec[tensor_d];
    // if end of tensor size chunk, check view
    if ((tensor_d == 0)
        || (shape_vec[tensor_d - 1] != 1
            && stride[tensor_d - 1] != tensor_numel * chunk_base_stride)) {
      while (view_d >= 0 && (view_numel < tensor_numel || tgt_shape_vec[view_d] == 1)) {
        target_stride[view_d] = view_numel * chunk_base_stride;
        view_numel *= tgt_shape_vec[view_d];
        view_d--;
      }
      if (view_numel != tensor_numel) { return NullOpt; }
      if (tensor_d > 0) {
        chunk_base_stride = stride[tensor_d - 1];
        tensor_numel = 1;
        view_numel = 1;
      }
    }
  }
  if (view_d != -1) { return NullOpt; }
  return target_stride;
}

Maybe<Shape> InferShapeUnspecifiedDim(const int64_t& elem_count, const Shape& shape) {
  int need_infer_axis = -1;