message: replace old-style thread ID computation
diff: @@ -872,7 +872,7 @@ __global__ __launch_bounds__(default_block_size) void check_unsorted(
  }
  block.sync();
  - auto row = threadIdx.x + blockDim.x * static_cast<IndexType>(blockIdx.x);
  + auto row = thread::get_thread_id_flat<IndexType>();
  if (row >= num_rows) {
  return;
  }
  