message: Spatial convolutions: add missing `&` qualifier.
  I don't think this has any performance implications, but I'm not completely sure.
diff: @@ -109,7 +109,7 @@ struct gemm_pack_colmajor_block<
  unpacket_traits<Packet>::masked_store_available>;
  EIGEN_DONT_INLINE
  - void operator()(Scalar* block, const DataMapper rhs, StorageIndex rows,
  + void operator()(Scalar* block, const DataMapper& rhs, StorageIndex rows,
  StorageIndex cols) {
  const bool standard_patches = !rhs.nonStandardPatches();
  @@ -170,7 +170,7 @@ struct gemm_pack_colmajor_block<
  // padded region of original input.
  template <bool patch_depth_is_multiple_of_packet_size, bool has_padding>
  EIGEN_ALWAYS_INLINE void packStandardPatches(Scalar* block,
  - const DataMapper rhs,
  + const DataMapper& rhs,
  StorageIndex rows,
  StorageIndex cols) {
  eigen_assert(!rhs.nonStandardPatches());
  @@ -350,7 +350,7 @@ struct gemm_pack_colmajor_block<
  template <bool patch_depth_is_multiple_of_packet_size>
  EIGEN_ALWAYS_INLINE void packNonStandardPatches(Scalar* block,
  - const DataMapper rhs,
  + const DataMapper& rhs,
  StorageIndex rows,
  StorageIndex cols) {
  eigen_assert(rhs.nonStandardPatches());
  