Function UnsortedSegmentSumGrad

tensorflow/cc/gradients/math_grad.cc:1325–1344

REGISTER_GRADIENT_OP("UnsortedSegmentMin", UnsortedSegmentMinOrMaxGrad);

Status UnsortedSegmentSumGrad(const Scope& scope, const Operation& op,
                              const std::vector<Output>& grad_inputs,
                              std::vector<Output>* grad_outputs) {
  if (op.num_inputs() != 3) {
    return errors::InvalidArgument("UnsortedSegmentSum requires 3 arguments");
  }

  if (grad_inputs.size() != 1) {
    return errors::InvalidArgument(
        "UnsortedSegmentSum grad requires 1 grad input");
  }

  auto zero_clipped_indices = GetZeroClippedIndices(scope, op.input(1));
  auto is_positive = GetIsPositive(scope, grad_inputs[0], op.input(1));
  grad_outputs->push_back(GatherDropNegatives(
      scope, grad_inputs[0], zero_clipped_indices, is_positive));
  grad_outputs->push_back(NoGradient());
  grad_outputs->push_back(NoGradient());
  return scope.status();
}

REGISTER_GRADIENT_OP("UnsortedSegmentSum", UnsortedSegmentSumGrad);