Cross.cpp

#define TORCH_ASSERT_ONLY_METHOD_OPERATORS
#include <ATen/native/Cross.h>
#include <ATen/core/Tensor.h>
#include <ATen/Dispatch.h>
#include <ATen/TensorMeta.h>
#include <ATen/WrapDimUtils.h>
#include <ATen/ExpandUtils.h>
#include <ATen/native/Resize.h>


#ifndef AT_PER_OPERATOR_HEADERS
#include <ATen/Functions.h>
#include <ATen/NativeFunctions.h>
#else
#include <ATen/ops/cross_native.h>
#include <ATen/ops/linalg_cross.h>
#include <ATen/ops/linalg_cross_native.h>
#endif

namespace at {
namespace meta {

TORCH_META_FUNC(linalg_cross)
(const Tensor & input, const Tensor & other, int64_t dim) {
  auto x_d = input.dim();
  auto y_d = other.dim();
  // This is to avoid things like
  // linalg.cross(torch.randn(2, 3), torch.randn(5, 2, 3), dim=2)
  TORCH_CHECK(x_d == y_d, "linalg.cross: inputs must have the same number of dimensions.");
  TORCH_CHECK(input.size(dim) == 3 && other.size(dim) == 3, "linalg.cross: inputs dimension ", dim, " must have length 3. Got ", input.size(dim), " and ", other.size(dim));

  // Broadcast the batch dimension of input and other.
  // Since the non-batch dimensions agree, this is the same as broadcast all the inputs
  auto out_size = infer_size(input.sizes(), other.sizes());

  set_output_raw_strided(0, out_size, {}, input.options());
}

}
namespace native {

DEFINE_DISPATCH(cross_stub);

static int64_t _default_cross_dim(const c10::optional<int64_t> &dimension, SymIntArrayRef sizes) {
  // If dimension is not given, it defaults to the first dimension found with the size 3.
  // Note that this behaviour might be unexpected.
  // _default_cross_dim is called internally inside the cross implementation to calculate
  // the dim and finally cross delegates to the linalg_cross implementation with this dim
  if(dimension.has_value()) {
    return *dimension;
  }

  for(auto i : c10::irange(sizes.size())) {
    if(sizes[i] == 3) {
      return i;
    }
  }
  TORCH_CHECK(false, "no dimension of size 3 in input");
}

Tensor cross(const Tensor & input, const Tensor & other, const c10::optional<int64_t> dimension) {
  auto dim = _default_cross_dim(dimension, input.sym_sizes());
  return at::linalg_cross(input, other, dim);
}

Tensor & cross_out(const Tensor & input, const Tensor & other, const c10::optional<int64_t> dimension, Tensor & out) {
  auto dim = _default_cross_dim(dimension, input.sym_sizes());
  return at::linalg_cross_out(out, input, other, dim);
}


TORCH_IMPL_FUNC(linalg_cross_out)
(const Tensor & input, const Tensor & other, int64_t dim, const Tensor & out) {
  dim = maybe_wrap_dim(dim, input.dim());
  auto out_size = out.sizes();
  Tensor input_broadcasted = input.expand(out_size);
  Tensor other_broadcasted = other.expand(out_size);

  cross_stub(input.device().type(), out, input_broadcasted, other_broadcasted, dim);
}

}} // namespace at::native