message: [XLA] Avoid signed overflow in dot interpreter
  Do the arithmetic in unsigned instead. Found by UBSan.
diff: @@ -1389,9 +1389,10 @@ class HloEvaluatorTypedVisitor : public DfsHloVisitorWithDefault {
  *(accumulate_index_locations[i].second) = accumulate_index[i];
  }
  + ElementwiseT lhs_val(lhs_literal.Get<ReturnT>(lhs_index));
  + ElementwiseT rhs_val(rhs_literal.Get<ReturnT>(rhs_index));
  result_val +=
  - static_cast<ElementwiseT>(lhs_literal.Get<ReturnT>(lhs_index)) *
  - static_cast<ElementwiseT>(rhs_literal.Get<ReturnT>(rhs_index));
  + ToArithmeticSafeType(lhs_val) * ToArithmeticSafeType(rhs_val);
  // If there are no contracting dimension accumulate_index_sizes is
  // empty, do not try to count down from -1 to 0 since it is and
  