message: [XLA] Buffer assignment: log total memory usage
diff: @@ -720,12 +720,15 @@ string BufferAssignment::ToString() const {
  string output;
  absl::StrAppend(&output, "BufferAssignment:\n");
  std::vector<const HloValue*> used_values;
  + int64 total_size = 0;
  for (auto& allocation : allocations_) {
  + total_size += allocation.size();
  absl::StrAppend(&output, allocation.ToString());
  for (const auto& p : allocation.assigned_buffers()) {
  used_values.push_back(p.first);
  }
  }
  + absl::StrAppend(&output, "\nTotal bytes used: ", total_size, "\n");
  absl::StrAppend(&output, "\nUsed values:\n");
  absl::c_sort(used_values, &CompareHloValuesById);
  for (const HloValue* value : used_values) {
  