message: TFL: slightly speed up reference::Softmax by avoiding unnecessary float->double cast.
  The original logic is a bit weird that the calculation is in double while the accumulator is in float. Also in general, beta doesn't have a huge significant figures.
diff: @@ -43,20 +43,18 @@ inline void Softmax(const SoftmaxParams& params,
  max = std::max(max, input_data[i * depth + c]);
  }
  - // TODO(b/148114827): Improve this code.
  // Compute sum.
  float sum = 0.f;
  for (int c = 0; c < depth; ++c) {
  - sum += std::exp(static_cast<double>(input_data[i * depth + c] - max) *
  - params.beta);
  + sum += std::exp((input_data[i * depth + c] - max) *
  + static_cast<float>(params.beta));
  }
  // Compute result.
  for (int c = 0; c < depth; ++c) {
  - output_data[i * depth + c] =
  - std::exp(static_cast<double>(input_data[i * depth + c] - max) *
  - params.beta) /
  - static_cast<double>(sum);
  + output_data[i * depth + c] = std::exp((input_data[i * depth + c] - max) *
  + static_cast<float>(params.beta)) /
  + sum;
  }
  }
  }
  