Function handmade_aligned_malloc

include/Eigen/src/Core/util/Memory.h:142–155

\internal Like malloc, but the returned pointer is guaranteed to be aligned to `alignment`. * Fast, but wastes `alignment` additional bytes of memory. Does not throw any exception. */

 * Fast, but wastes `alignment` additional bytes of memory. Does not throw any exception.
 */
EIGEN_DEVICE_FUNC inline void* handmade_aligned_malloc(std::size_t size,
                                                       std::size_t alignment = EIGEN_DEFAULT_ALIGN_BYTES) {
  eigen_assert(alignment >= sizeof(void*) && alignment <= 128 && (alignment & (alignment - 1)) == 0 &&
               "Alignment must be at least sizeof(void*), less than or equal to 128, and a power of 2");

  check_that_malloc_is_allowed();
  EIGEN_USING_STD(malloc)
  void* original = malloc(size + alignment);
  if (original == nullptr) return nullptr;
  uint8_t offset = static_cast<uint8_t>(alignment - (reinterpret_cast<std::size_t>(original) & (alignment - 1)));
  void* aligned = static_cast<void*>(static_cast<uint8_t*>(original) + offset);
  *(static_cast<uint8_t*>(aligned) - 1) = offset;
  return aligned;
}

/** \internal Frees memory allocated with handmade_aligned_malloc */
EIGEN_DEVICE_FUNC inline void handmade_aligned_free(void* ptr) {