Function CheckRedzoneHost

tensorflow/stream_executor/cuda/redzone_allocator.cc:179–208

Check that redzones weren't overwritten on a host. Slower, but gives a more useful error message.

//
// Slower, but gives a more useful error message.
static port::StatusOr<RedzoneCheckStatus> CheckRedzoneHost(
    DeviceMemoryBase redzone, DeviceMemoryBase user_allocation,
    absl::string_view name, Stream* stream, uint8 redzone_pattern) {
  uint64 size = redzone.size();
  auto redzone_data = absl::make_unique<uint8[]>(size);
  TF_RETURN_IF_ERROR(stream->ThenMemcpy(redzone_data.get(), redzone, size)
                         .BlockHostUntilDone());

  std::array<uint8, sizeof(uint64)> pattern_arr;
  pattern_arr.fill(redzone_pattern);
  uint64 pattern64;
  std::memcpy(&pattern64, pattern_arr.data(), sizeof(uint64));

  int64 i;
  for (i = 0; i + 7 < size; i += sizeof(uint64)) {
    uint64 rz_value = *reinterpret_cast<uint64*>(&redzone_data[i]);
    if (rz_value != pattern64) {
      return RedzoneCheckStatus(name, user_allocation.opaque(), i, pattern64,
                                rz_value);
    }
  }
  for (; i < size; ++i) {
    uint8 rz_value = redzone_data[i];
    if (rz_value != redzone_pattern) {
      return RedzoneCheckStatus(name, user_allocation.opaque(), i,
                                redzone_pattern, rz_value);
    }
  }
  return RedzoneCheckStatus::OK();
}

// Run the redzone checker on the provided buffer redzone.
//