message: add pointer doubling kernel
diff: @@ -59,6 +59,19 @@ __global__ __launch_bounds__(default_block_size) void build_postorder_cols(
  }
  +template <typename IndexType>
  +__global__ __launch_bounds__(default_block_size) void pointer_doubling_kernel(
  + IndexType num_rows, const IndexType* parents, IndexType* doubled_parents)
  +{
  + const auto row = thread::get_thread_id_flat<IndexType>();
  + if (row >= num_rows) {
  + return;
  + }
  + const auto parent = parents[row];
  + doubled_parents[row] = parent < num_rows ? parents[parent] : num_rows;
  +}
  +
  +
  template <typename IndexType>
  __global__
  __launch_bounds__(default_block_size) void cholesky_symbolic_count_kernel(
  