inline void BiasAndClamp(float clamp_min, float clamp_max, int bias_size,
                         const float* bias_data, int array_size,
                         float* array_data) {
  if (bias_size == 0) return;
  // Note: see b/132215220: in May 2019 we thought it would be OK to replace
  // this with the Eigen one-liner:
  //   return (array.colwise() + bias).cwiseMin(clamp_max).cwiseMin(clamp_max).
  // This turned out to severely regress performance: +4ms (i.e. 8%) on
  // MobileNet v2 / 1.0 / 224. So we keep custom NEON code for now.
  TFLITE_DCHECK_EQ((array_size % bias_size), 0);
#ifdef USE_NEON
  float* array_ptr = array_data;
  float* array_end_ptr = array_ptr + array_size;
  const auto clamp_min_vec = vdupq_n_f32(clamp_min);
  const auto clamp_max_vec = vdupq_n_f32(clamp_max);
  for (; array_ptr != array_end_ptr; array_ptr += bias_size) {
    int i = 0;
    for (; i <= bias_size - 16; i += 16) {
      auto b0 = vld1q_f32(bias_data + i);
      auto b1 = vld1q_f32(bias_data + i + 4);
      auto b2 = vld1q_f32(bias_data + i + 8);
      auto b3 = vld1q_f32(bias_data + i + 12);
      auto a0 = vld1q_f32(array_ptr + i);
      auto a1 = vld1q_f32(array_ptr + i + 4);
      auto a2 = vld1q_f32(array_ptr + i + 8);
      auto a3 = vld1q_f32(array_ptr + i + 12);
      auto x0 = vaddq_f32(a0, b0);
      auto x1 = vaddq_f32(a1, b1);
      auto x2 = vaddq_f32(a2, b2);
      auto x3 = vaddq_f32(a3, b3);
      x0 = vmaxq_f32(clamp_min_vec, x0);
      x1 = vmaxq_f32(clamp_min_vec, x1);
      x2 = vmaxq_f32(clamp_min_vec, x2);
      x3 = vmaxq_f32(clamp_min_vec, x3);
      x0 = vminq_f32(clamp_max_vec, x0);
      x1 = vminq_f32(clamp_max_vec, x1);
      x2 = vminq_f32(clamp_max_vec, x2);
      x3 = vminq_f32(clamp_max_vec, x3);
      vst1q_f32(array_ptr + i, x0);
      vst1q_f32(array_ptr + i + 4, x1);
      vst1q_f32(array_ptr + i + 8, x2);
      vst1q_f32(array_ptr + i + 12, x3);
    }
    for (; i <= bias_size - 4; i += 4) {
      auto b = vld1q_f32(bias_data + i);
      auto a = vld1q_f32(array_ptr + i);
      auto x = vaddq_f32(a, b);
      x = vmaxq_f32(clamp_min_vec, x);
      x = vminq_f32(clamp_max_vec, x);
      vst1q_f32(array_ptr + i, x);
    }
    for (; i < bias_size; i++) {
      array_ptr[i] = ActivationFunctionWithMinMax(array_ptr[i] + bias_data[i],
                                                  clamp_min, clamp_max);
    }
  }
#else  // not NEON
  for (int array_offset = 0; array_offset < array_size;
       array_offset += bias_size) {
    for (int i = 0; i < bias_size; i++) {
      array_data[array_offset + i] = ActivationFunctionWithMinMax(
          array_data[array_offset + i] + bias_data[i], clamp_min, clamp_max);
    }
  }
#endif
}


log_x_for_x_greater_than_or_equal_to_1_impl(
    gemmlowp::FixedPoint<int32_t, InputIntegerBits> input_val) {
  // assert(__builtin_clz(0u) >= std::numeric_limits<uint32_t>::digits - 1);
  // assert(__builtin_clz(0u) <= std::numeric_limits<uint32_t>::digits);
  using FixedPoint0 = gemmlowp::FixedPoint<int32_t, 0>;
  // The reason for accumulating the result with an extra bit of headroom is
  // that z_pow_2_adj * log_2 might be saturated, and adding num_scaled *
  // recip_denom will otherwise introduce an error.
  static constexpr int kAccumIntegerBits = OutputIntegerBits + 1;
  using FixedPointAccum = gemmlowp::FixedPoint<int32_t, kAccumIntegerBits>;

  const FixedPoint0 log_2 = GEMMLOWP_CHECKED_FIXEDPOINT_CONSTANT(
      FixedPoint0, 1488522236, std::log(2.0));
  const FixedPoint0 sqrt_sqrt_half = GEMMLOWP_CHECKED_FIXEDPOINT_CONSTANT(
      FixedPoint0, 1805811301, std::sqrt(std::sqrt(0.5)));
  const FixedPoint0 sqrt_half = GEMMLOWP_CHECKED_FIXEDPOINT_CONSTANT(
      FixedPoint0, 1518500250, std::sqrt(0.5));
  const FixedPoint0 one_quarter =
      GEMMLOWP_CHECKED_FIXEDPOINT_CONSTANT(FixedPoint0, 536870912, 1.0 / 4.0);

  const FixedPoint0 alpha_n = GEMMLOWP_CHECKED_FIXEDPOINT_CONSTANT(
      FixedPoint0, 117049297, 11.0 / 240.0 * std::sqrt(std::sqrt(2.0)));
  const FixedPoint0 alpha_d = GEMMLOWP_CHECKED_FIXEDPOINT_CONSTANT(
      FixedPoint0, 127690142, 1.0 / 20.0 * std::sqrt(std::sqrt(2.0)));
  const FixedPoint0 alpha_i = GEMMLOWP_CHECKED_FIXEDPOINT_CONSTANT(
      FixedPoint0, 1057819769,
      2.0 / std::sqrt(std::sqrt(2.0)) - std::sqrt(std::sqrt(2.0)));
  const FixedPoint0 alpha_f = GEMMLOWP_CHECKED_FIXEDPOINT_CONSTANT(
      FixedPoint0, 638450708, 1.0 / 4.0 * std::sqrt(std::sqrt(2.0)));

  const FixedPointAccum shifted_quarter =
      gemmlowp::Rescale<kAccumIntegerBits>(one_quarter);

  // Reinterpret the input value as Q0.31, because we will figure out the
  // required shift "ourselves" instead of using, say, Rescale.
  FixedPoint0 z_a = FixedPoint0::FromRaw(input_val.raw());
  // z_a_pow_2 = input_integer_bits - z_a_headroom;
  int z_a_headroom_plus_1 = CountLeadingZeros(static_cast<uint32_t>(z_a.raw()));
  FixedPoint0 r_a_tmp =
      SaturatingRoundingMultiplyByPOTParam(z_a, (z_a_headroom_plus_1 - 1));
  const int32_t r_a_raw =
      SaturatingRoundingMultiplyByPOTParam((r_a_tmp * sqrt_half).raw(), 1);
  // z_pow_2_adj = max(z_pow_2_a - 0.75, z_pow_2_b - 0.25);
  // z_pow_2_adj = max(InputIntegerBits - z_a_headroom_plus_1 + 0.25,
  //                   InputIntegerBits - z_b_headroom - 0.25);
  const FixedPointAccum z_a_pow_2_adj = SaturatingAddNonGemmlowp(
      FixedPointAccum::FromRaw(SaturatingRoundingMultiplyByPOTParam(
          static_cast<int32_t>(InputIntegerBits - z_a_headroom_plus_1),
          31 - kAccumIntegerBits)),
      shifted_quarter);

  // z_b is treated like z_a, but premultiplying by sqrt(0.5).
  FixedPoint0 z_b = z_a * sqrt_half;
  int z_b_headroom = CountLeadingZeros(static_cast<uint32_t>(z_b.raw())) - 1;
  const int32_t r_b_raw =
      SaturatingRoundingMultiplyByPOTParam(z_a.raw(), z_b_headroom);
  const FixedPointAccum z_b_pow_2_adj = SaturatingSub(
      FixedPointAccum::FromRaw(SaturatingRoundingMultiplyByPOTParam(
          static_cast<int32_t>(InputIntegerBits - z_b_headroom),
          31 - kAccumIntegerBits)),
      shifted_quarter);

  const FixedPoint0 r = FixedPoint0::FromRaw(std::min(r_a_raw, r_b_raw));
  const FixedPointAccum z_pow_2_adj = FixedPointAccum::FromRaw(
      std::max(z_a_pow_2_adj.raw(), z_b_pow_2_adj.raw()));

  const FixedPoint0 p = gemmlowp::RoundingHalfSum(r, sqrt_sqrt_half);
  FixedPoint0 q = r - sqrt_sqrt_half;
  q = q + q;

  const FixedPoint0 common_sq = q * q;
  const FixedPoint0 num = q * r + q * common_sq * alpha_n;
  const FixedPoint0 denom_minus_one_0 =
      p * (alpha_i + q + alpha_d * common_sq) + alpha_f * q;
  const FixedPoint0 recip_denom =
      one_over_one_plus_x_for_x_in_0_1(denom_minus_one_0);

  const FixedPointAccum num_scaled = gemmlowp::Rescale<kAccumIntegerBits>(num);
  return gemmlowp::Rescale<OutputIntegerBits>(z_pow_2_adj * log_2 +
                                              num_scaled * recip_denom);
}

[lite] Add check for bias_size is zero to avoid division by zero. This shouldn't happen for properly converted models. Just safety check

PiperOrigin-RevId: 416383645
Change-Id: If8e508bf696ae8ecfb927e69c139a8ccf7fe60cb


inline int32x4x4_t MultiplyByQuantizedMultiplier4Rows(
    int32x4x4_t input_val, int32_t quantized_multiplier, int shift) {
  TFLITE_DCHECK(quantized_multiplier >= 0);

  const int right_shift = std::min(-1, shift);
  const int left_shift = shift - right_shift;

  const int32x4_t multiplier_dup = vdupq_n_s32(quantized_multiplier);
  const int32x4_t left_shift_dup = vdupq_n_s32(left_shift);
  const int32x4_t right_shift_dup = vdupq_n_s32(right_shift);

  int32x4x4_t result;
  result.val[0] = vrshlq_s32(
      vqdmulhq_s32(vshlq_s32(input_val.val[0], left_shift_dup), multiplier_dup),
      right_shift_dup);

  result.val[1] = vrshlq_s32(
      vqdmulhq_s32(vshlq_s32(input_val.val[1], left_shift_dup), multiplier_dup),
      right_shift_dup);

  result.val[2] = vrshlq_s32(
      vqdmulhq_s32(vshlq_s32(input_val.val[2], left_shift_dup), multiplier_dup),
      right_shift_dup);

  result.val[3] = vrshlq_s32(
      vqdmulhq_s32(vshlq_s32(input_val.val[3], left_shift_dup), multiplier_dup),
      right_shift_dup);

  return result;
}


inline Integer FloorLog2(Integer n) {
  static_assert(std::is_integral<Integer>::value, "");
  static_assert(std::is_signed<Integer>::value, "");
  static_assert(sizeof(Integer) == 4 || sizeof(Integer) == 8, "");
  TFLITE_CHECK_GT(n, 0);
  if (sizeof(Integer) == 4) {
    return 30 - CountLeadingSignBits(n);
  } else {
    return 62 - CountLeadingSignBits(n);
  }
}


inline std::int32_t SaturatingSub(std::int32_t a, std::int32_t b) {
  std::int64_t a64 = a;
  std::int64_t b64 = b;
  std::int64_t diff = a64 - b64;
  return static_cast<std::int32_t>(std::min(
      static_cast<std::int64_t>(std::numeric_limits<std::int32_t>::max()),
      std::max(
          static_cast<std::int64_t>(std::numeric_limits<std::int32_t>::min()),
          diff)));
}


Integer RoundDown(Integer i) {
  return i - (i % Modulus);
}


inline void GetActivationMinMax(FusedActivationFunctionType ac,
                                float* output_activation_min,
                                float* output_activation_max) {
  switch (ac) {
    case FusedActivationFunctionType::kNone:
      *output_activation_min = std::numeric_limits<float>::lowest();
      *output_activation_max = std::numeric_limits<float>::max();
      break;
    case FusedActivationFunctionType::kRelu:
      *output_activation_min = 0.f;
      *output_activation_max = std::numeric_limits<float>::max();
      break;
    case FusedActivationFunctionType::kRelu1:
      *output_activation_min = -1.f;
      *output_activation_max = 1.f;
      break;
    case FusedActivationFunctionType::kRelu6:
      *output_activation_min = 0.f;
      *output_activation_max = 6.f;
      break;
  }
}


inline int CountLeadingSignBits(T integer_input) {
  static_assert(std::is_signed<T>::value, "Only signed integer types handled.");
#if defined(__GNUC__) && !defined(__clang__)
  return integer_input ? __builtin_clrsb(integer_input)
                       : std::numeric_limits<T>::digits;
#else
  using U = typename std::make_unsigned<T>::type;
  return integer_input >= 0
             ? CountLeadingZeros(static_cast<U>(integer_input)) - 1
         : integer_input != std::numeric_limits<T>::min()
             ? CountLeadingZeros(2 * static_cast<U>(-integer_input) - 1)
             : 0;
#endif
}


inline int32x4x4_t MultiplyByQuantizedMultiplier4Rows(
    int32x4x4_t input_val, int32_t quantized_multiplier, int shift) {
  const int left_shift = std::max(shift, 0);
  const int right_shift = std::min(shift, 0);
  int32x4x4_t result;

  int32x4_t multiplier_dup = vdupq_n_s32(quantized_multiplier);
  int32x4_t left_shift_dup = vdupq_n_s32(left_shift);
  int32x4_t right_shift_dup = vdupq_n_s32(right_shift);

  result.val[0] =
      vrshlq_s32(vqrdmulhq_s32(vshlq_s32(input_val.val[0], left_shift_dup),
                               multiplier_dup),
                 right_shift_dup);

  result.val[1] =
      vrshlq_s32(vqrdmulhq_s32(vshlq_s32(input_val.val[1], left_shift_dup),
                               multiplier_dup),
                 right_shift_dup);

  result.val[2] =
      vrshlq_s32(vqrdmulhq_s32(vshlq_s32(input_val.val[2], left_shift_dup),
                               multiplier_dup),
                 right_shift_dup);

  result.val[3] =
      vrshlq_s32(vqrdmulhq_s32(vshlq_s32(input_val.val[3], left_shift_dup),
                               multiplier_dup),
                 right_shift_dup);

  return result;
}


inline LutOutT lut_lookup_with_interpolation(int16_t value,
                                             const LutOutT* lut) {
  static_assert(std::is_same<LutOutT, int8_t>::value ||
                    std::is_same<LutOutT, int16_t>::value,
                "Only LUTs with int8 or int16 outputs are supported.");
  // 512 base values, lut[513] is only used to calculate the slope
  const uint16_t index = static_cast<uint16_t>(256 + (value >> 7));
  assert(index < 512 && "LUT index out of range.");
  const int16_t offset = value & 0x7f;

  // Base and slope are Q0.x
  const LutOutT base = lut[index];
  const LutOutT slope = lut[index + 1] - lut[index];

  // Q0.x * Q0.7 = Q0.(x + 7)
  // Round and convert from Q0.(x + 7) to Q0.x
  const int delta = (slope * offset + 64) >> 7;

  // Q0.15 + Q0.15
  return static_cast<LutOutT>(base + delta);
}


inline int32_t MultiplyByQuantizedMultiplierSmallerThanOneExp(
    int32_t x, int32_t quantized_multiplier, int shift) {
  TFLITE_DCHECK_LE(shift, 0);
  return MultiplyByQuantizedMultiplier(x, quantized_multiplier, shift);
}


inline int32_t MultiplyByQuantizedMultiplierSmallerThanOneExp(
    int32_t x, int32_t quantized_multiplier, int left_shift) {
  using gemmlowp::RoundingDivideByPOT;
  using gemmlowp::SaturatingRoundingDoublingHighMul;
  return RoundingDivideByPOT(
      SaturatingRoundingDoublingHighMul(x, quantized_multiplier), -left_shift);
}


IntegerType SaturatingRoundingMultiplyByPOTParam(IntegerType x, int exponent) {
  if (exponent == 0) {
    return x;
  }
  using ScalarIntegerType =
      typename gemmlowp::FixedPointRawTypeTraits<IntegerType>::ScalarRawType;
  const IntegerType min =
      gemmlowp::Dup<IntegerType>(std::numeric_limits<ScalarIntegerType>::min());
  const IntegerType max =
      gemmlowp::Dup<IntegerType>(std::numeric_limits<ScalarIntegerType>::max());
  const int ScalarIntegerTypeBits = 8 * sizeof(ScalarIntegerType);

  const std::int32_t threshold =
      ((1 << (ScalarIntegerTypeBits - 1 - exponent)) - 1);
  const IntegerType positive_mask =
      gemmlowp::MaskIfGreaterThan(x, gemmlowp::Dup<IntegerType>(threshold));
  const IntegerType negative_mask =
      gemmlowp::MaskIfLessThan(x, gemmlowp::Dup<IntegerType>(-threshold));

  IntegerType result = gemmlowp::ShiftLeft(x, exponent);
  result = gemmlowp::SelectUsingMask(positive_mask, max, result);
  result = gemmlowp::SelectUsingMask(negative_mask, min, result);
  return result;
}


inline void NDOpsHelper(const NdArrayDesc<N>& output, const Calc& calc) {
  int indexes[N] = {0};
  NDOpsHelperImpl<N, 0, Calc>(output, calc, indexes);
}


inline int8_t lut_lookup(int16_t value, const int8_t* lut) {
  return lut_lookup_with_interpolation(value, lut);
}


inline std::int16_t SaturatingSub(std::int16_t a, std::int16_t b) {
  std::int32_t a32 = a;
  std::int32_t b32 = b;
  std::int32_t diff = a32 - b32;
  return static_cast<std::int16_t>(
      std::min(static_cast<int32_t>(32767),
               std::max(static_cast<int32_t>(-32768), diff)));
}


inline int SubscriptToIndex(const NdArrayDesc<8>& desc, int indexes[8]) {
  return indexes[0] * desc.strides[0] + indexes[1] * desc.strides[1] +
         indexes[2] * desc.strides[2] + indexes[3] * desc.strides[3] +
         indexes[4] * desc.strides[4] + indexes[5] * desc.strides[5] +
         indexes[6] * desc.strides[6] + indexes[7] * desc.strides[7];
}


inline int16_t lut_lookup(int8_t value, const int16_t* lut) {
  return lut[128 + value];
}


inline int32_t MultiplyByQuantizedMultiplierGreaterThanOne(
    int32_t x, int32_t quantized_multiplier, int left_shift) {
  using gemmlowp::SaturatingRoundingDoublingHighMul;
  return SaturatingRoundingDoublingHighMul(x * (1 << left_shift),
                                           quantized_multiplier);
}


inline T ActivationFunctionWithMinMax(T x, T output_activation_min,
                                      T output_activation_max) {
  using std::max;
  using std::min;
  return min(max(x, output_activation_min), output_activation_max);
}


constexpr int min_log_x_output_bits(int input_bits) {
  return input_bits > 90   ? 7
         : input_bits > 44 ? 6
         : input_bits > 21 ? 5
         : input_bits > 10 ? 4
         : input_bits > 4  ? 3
         : input_bits > 1  ? 2
                           : 1;
}


inline int16_t lut_lookup(int16_t value, const int16_t* lut) {
  return lut_lookup_with_interpolation(value, lut);
}


inline void NdArrayDescsForElementwiseBroadcast(
    const RuntimeShape& input0_shape, const RuntimeShape& input1_shape,
    const RuntimeShape& input2_shape, NdArrayDesc<N>* desc0_out,
    NdArrayDesc<N>* desc1_out, NdArrayDesc<N>* desc2_out) {
  TFLITE_DCHECK(desc0_out != nullptr);
  TFLITE_DCHECK(desc1_out != nullptr);
  TFLITE_DCHECK(desc2_out != nullptr);

  auto extended_input0_shape = RuntimeShape::ExtendedShape(N, input0_shape);
  auto extended_input1_shape = RuntimeShape::ExtendedShape(N, input1_shape);
  auto extended_input2_shape = RuntimeShape::ExtendedShape(N, input2_shape);

  // Copy dims to desc, calculating strides.
  CopyDimsToDesc<N>(extended_input0_shape, desc0_out);
  CopyDimsToDesc<N>(extended_input1_shape, desc1_out);
  CopyDimsToDesc<N>(extended_input2_shape, desc2_out);

  // Walk over each dimension. If the extents are equal do nothing.
  // Otherwise, set the desc with extent 1 to have extent equal to the other and
  // stride 0.
  for (int i = 0; i < N; ++i) {
    const int extent0 = extended_input0_shape.Dims(i);
    const int extent1 = extended_input1_shape.Dims(i);
    const int extent2 = extended_input2_shape.Dims(i);

    int extent = extent0;
    if (extent1 != 1) extent = extent1;
    if (extent2 != 1) extent = extent2;

    TFLITE_DCHECK(extent0 == 1 || extent0 == extent);
    TFLITE_DCHECK(extent1 == 1 || extent1 == extent);
    TFLITE_DCHECK(extent2 == 1 || extent2 == extent);

    if (!(extent0 == extent1 && extent1 == extent2)) {
      if (extent0 == 1) {
        desc0_out->strides[i] = 0;
        desc0_out->extents[i] = extent;
      }
      if (extent1 == 1) {
        desc1_out->strides[i] = 0;
        desc1_out->extents[i] = extent;
      }
      if (extent2 == 1) {
        desc2_out->strides[i] = 0;
        desc2_out->extents[i] = extent;
      }
    }
  }
}


inline int32_t MultiplyByQuantizedMultiplierGreaterThanOne(
    int32_t x, int32_t quantized_multiplier, int shift) {
  TFLITE_DCHECK_GE(shift, 0);
  return MultiplyByQuantizedMultiplier(x, quantized_multiplier, shift);
}


Status DependencyOptimizer::OptimizeDependencies() {
  SetVector<int> nodes_to_simplify;
  std::set<int> nodes_to_delete;
  for (int i = 0; i < optimized_graph_->node_size(); ++i) {
    const NodeDef& node = optimized_graph_->node(i);
    if (IsNoOp(node) || IsIdentity(node) || IsIdentityN(node) ||
        IsConstant(node) || SafeToConvertToNoOp(node)) {
      nodes_to_simplify.PushBack(i);
    }
  }
  while (!nodes_to_simplify.Empty()) {
    int node_to_simplify = nodes_to_simplify.PopBack();
    // Discard nodes that were marked for deletion already.
    while (nodes_to_delete.find(node_to_simplify) != nodes_to_delete.end()) {
      node_to_simplify = nodes_to_simplify.PopBack();
    }
    OptimizeNode(node_to_simplify, &nodes_to_simplify, &nodes_to_delete);
  }

  if (fetch_nodes_known_) {
    VLOG(1) << "Deleted " << nodes_to_delete.size() << " out of "
            << optimized_graph_->node_size() << " nodes.";
    EraseNodesFromGraph(nodes_to_delete, optimized_graph_);
    node_map_.reset(new NodeMap(optimized_graph_));
    BuildNodeToIdx();
  }
  return Status::OK();
}

Prevent a null-pointer dereference / `CHECK`-fail in grappler.

PiperOrigin-RevId: 409187354
Change-Id: I369c249cca32e6c56ec193f0ebbf2f2768fc7d43


bool RemoveControlInput(NodeDef* node, const string& control_input_to_remove,
                        NodeMap* node_map) {
  for (int pos = node->input_size() - 1; pos >= 0; --pos) {
    const string& input = node->input(pos);
    if (input[0] != '^') break;
    if (input == control_input_to_remove) {
      node->mutable_input()->SwapElements(pos, node->input_size() - 1);
      node->mutable_input()->RemoveLast();
      node_map->RemoveOutput(NodeName(input), node->name());
      return true;
    }
  }
  return false;
}


Status DependencyOptimizer::TransitiveReduction() {
  // PRECONDITION: optimized_graph_ must be sorted topologically.
  const int num_nodes = optimized_graph_->node_size();
  // Set up a compressed version of the graph to save a constant factor in the
  // expensive algorithm below. Also cache the set of control outputs and the
  // highest index of a target of any control output from each node.
  int num_controls = 0;
  std::vector<std::vector<int>> outputs(num_nodes);
  std::vector<gtl::InlinedVector<std::pair<int, int>, 2>> control_outputs(
      num_nodes);
  // target_range[i] contains the range of node indices for which to compute
  // longest paths starting from node i.
  std::vector<std::pair<int, int>> target_range(num_nodes, {num_nodes, -1});
  for (int node_idx = 0; node_idx < num_nodes; ++node_idx) {
    const NodeDef& node = optimized_graph_->node(node_idx);
    if (ModifiesFrameInfo(node) || !HasOpDef(node)) {
      // Ignore function nodes and nodes that modify frame info.
      continue;
    }
    for (int input_slot = 0; input_slot < node.input_size(); ++input_slot) {
      const string& input = node.input(input_slot);
      const NodeDef* input_node = node_map_->GetNode(input);
      if (ModifiesFrameInfo(*input_node) || IsMerge(*input_node)) {
        // Ignore edges from nodes that modify frame info and from Merge nodes,
        // because we cannot know which of it's input paths executes.
        continue;
      }
      const int input_node_idx = node_to_idx_[input_node];
      outputs[input_node_idx].push_back(node_idx);
      target_range[input_node_idx].first =
          std::min(target_range[input_node_idx].first, node_idx);
      if (IsControlInput(input)) {
        ++num_controls;
        control_outputs[input_node_idx].emplace_back(node_idx, input_slot);
        target_range[input_node_idx].second =
            std::max(target_range[input_node_idx].second, node_idx);
      }
    }
  }

  // Run the longest path in DAG algorithm for each source node that has control
  // outputs. If, for any target node of a control output, there exists a path
  // of length > 1, we can drop that control dependency.
  int num_controls_removed = 0;
  std::vector<DistanceFromSource> longest_distance(num_nodes);
  // Map from target_index -> set of (input_slot, source_index), representing
  // the control edges to remove. We sort them in reverse order by input slot,
  // such that when we swap them out so we don't clobber the
  // node(target).input() repeated field.
  typedef std::pair<int, int> InputSlotAndSource;
  absl::flat_hash_map<
      int, std::set<InputSlotAndSource, std::greater<InputSlotAndSource>>>
      control_edges_to_remove;
  for (int source = 0; source < num_nodes; ++source) {
    if (target_range[source].first >= target_range[source].second ||
        target_range[source].second <= source) {
      continue;
    }
    // Compute the set of nodes in the transitive fanout of source with
    // topological sort index in [target_range.first : target_range.second]]
    // to which there exists a path of length 2 or more from source.
    std::fill(longest_distance.begin() + target_range[source].first,
              longest_distance.begin() + target_range[source].second + 1, ZERO);
    LongestPathsLowerBounds(source, target_range[source], outputs,
                            &longest_distance);

    // If the longest path from source to target of a control dependency is
    // longer than 1, there exists an alternate path, and we can eliminate the
    // redundant direct control dependency.
    for (const auto& control_output : control_outputs[source]) {
      const int target = control_output.first;
      if (longest_distance[target] == TWO_OR_GREATER) {
        const int input_slot = control_output.second;
        control_edges_to_remove[target].emplace(input_slot, source);
      }
    }
  }
  for (const auto& it : control_edges_to_remove) {
    const int target = it.first;
    NodeDef* target_node = optimized_graph_->mutable_node(target);
    for (const InputSlotAndSource& slot_and_source : it.second) {
      const int input_slot = slot_and_source.first;
      const int source = slot_and_source.second;
      const NodeDef& source_node = optimized_graph_->node(source);
      CHECK_LT(input_slot, target_node->input_size());
      target_node->mutable_input()->SwapElements(input_slot,
                                                 target_node->input_size() - 1);
      node_map_->RemoveOutput(source_node.name(), target_node->name());
      target_node->mutable_input()->RemoveLast();
      ++num_controls_removed;
    }
  }
  VLOG(1) << "Removed " << num_controls_removed << " out of " << num_controls
          << " control dependencies";
  return Status::OK();
}


int DependencyOptimizer::NumEdgesIfBypassed(
    const NodeDef& node, const std::vector<NodeDef*>& output_nodes) const {
  const bool is_multi_input_identity_n =
      IsIdentityN(node) && !IsIdentityNSingleInput(node);
  const int num_outputs = output_nodes.size();
  const int num_inputs = node.input_size();

  if (is_multi_input_identity_n) {
    // multi-input identity_n with input/output control dependencies will likely
    // increase number of edges after optimization.
    int num_edges_if_bypassed(0);
    for (const string& input_node_name : node.input()) {
      if (IsControlInput(input_node_name)) {
        num_edges_if_bypassed += num_outputs;
      } else {
        ++num_edges_if_bypassed;
      }
    }

    for (auto consumer : output_nodes) {
      for (int j = 0; j < consumer->input_size(); ++j) {
        const TensorId consumer_input = ParseTensorName(consumer->input(j));
        if (consumer_input.node() == node.name()) {
          if (IsControlInput(consumer_input)) {
            num_edges_if_bypassed += num_inputs;
          } else {
            ++num_edges_if_bypassed;
          }
        }
      }
    }
    return num_edges_if_bypassed;
  } else {
    return num_inputs * num_outputs;
  }
}


void LongestPathsLowerBounds(
    int source, const std::pair<int, int>& target_range,
    const std::vector<std::vector<int>>& outputs,
    std::vector<DistanceFromSource>* longest_distance) {
  std::deque<int> queue;
  queue.emplace_front(source);
  while (!queue.empty()) {
    int node = queue.front();
    queue.pop_front();
    for (int fanout : outputs[node]) {
      // 1) Only nodes in the target range can be on paths from source to one of
      //    its control outputs.
      // 2) Since we only need a lower bound on the longest distance, we can
      //    skip nodes for which we have already proven have a path of
      //    length > 1 from the source.
      if (fanout >= target_range.first && fanout <= target_range.second &&
          (*longest_distance)[fanout] != TWO_OR_GREATER) {
        (*longest_distance)[fanout] =
            (*longest_distance)[fanout] == ZERO ? ONE : TWO_OR_GREATER;
        queue.emplace_front(fanout);
      }
    }
  }
}


void DependencyOptimizer::OptimizeNode(int node_idx,
                                       SetVector<int>* nodes_to_simplify,
                                       std::set<int>* nodes_to_delete) {
  NodeDef* node = optimized_graph_->mutable_node(node_idx);
  const bool is_noop = IsNoOp(*node);
  const bool is_identity = IsIdentity(*node) || IsIdentityNSingleInput(*node);
  const bool is_multi_input_identity =
      IsIdentityN(*node) && !IsIdentityNSingleInput(*node);
  const string node_name = node->name();
  // Constant nodes with no input control dependency are always executed early,
  // so we can prune all their output control dependencies.
  if (IsConstant(*node) && node->input_size() == 0) {
    const auto output_nodes = node_map_->GetOutputs(node_name);
    for (NodeDef* fanout : output_nodes) {
      bool optimize_fanout = false;
      bool data_connection = false;
      for (int i = fanout->input_size() - 1; i >= 0; --i) {
        const TensorId input_tensor = ParseTensorName(fanout->input(i));
        if (input_tensor.node() == node_name) {
          if (input_tensor.index() < 0) {
            fanout->mutable_input()->SwapElements(i, fanout->input_size() - 1);
            fanout->mutable_input()->RemoveLast();
            optimize_fanout = true;
          } else {
            data_connection = true;
          }
        }
      }
      if (optimize_fanout) {
        nodes_to_simplify->PushBack(node_to_idx_[fanout]);
        if (!data_connection) {
          node_map_->RemoveOutput(node_name, fanout->name());
        }
      }
    }
    if (node_map_->GetOutputs(node_name).empty() && fetch_nodes_known_ &&
        nodes_to_preserve_.find(node_name) == nodes_to_preserve_.end()) {
      // Mark the node for deletion.
      nodes_to_delete->insert(node_to_idx_[node]);
    }
    return;
  }

  // Change ops that only have control dependencies as outputs to NoOps.
  if (!is_noop && SafeToConvertToNoOp(*node)) {
    VLOG(2) << "***** Replacing  " << node_name << " (" << node->op()
            << ") with NoOp.";
    // The outputs of this node are not consumed. Replace its inputs with
    // control dependencies and replace the op itself with the NoOp op.
    std::unordered_set<string> ctrl_inputs;
    int pos = 0;
    while (pos < node->input_size()) {
      const string old_input = node->input(pos);
      if (IsControlInput(old_input)) {
        if (!ctrl_inputs.insert(old_input).second) {
          // We found a duplicate control input. Remove it.
          node->mutable_input()->SwapElements(pos, node->input_size() - 1);
          node->mutable_input()->RemoveLast();
        } else {
          ++pos;
        }
        continue;
      }
      // Replace a normal input with a control input.
      const string ctrl_input = ConstantFolding::AddControlDependency(
          old_input, optimized_graph_, node_map_.get());
      ctrl_inputs.insert(ctrl_input);
      node->set_input(pos, ctrl_input);
      node_map_->UpdateInput(node_name, old_input, ctrl_input);
      const NodeDef* old_input_node = node_map_->GetNode(old_input);
      nodes_to_simplify->PushBack(node_to_idx_[old_input_node]);
      ++pos;
    }
    node->set_op("NoOp");
    EraseRegularNodeAttributes(node);
    DedupControlInputs(node);
    nodes_to_simplify->PushBack(node_to_idx_[node]);
    return;
  }

  // Remove NoOp nodes if the product of their fan-in and fan-out is less than
  // or equal to the sum of the fan-in and fan-out. The non-trivial rewrites
  // take the following form:
  //
  // Case a)
  //    x --^> +------+                x --^> +---+
  //    y --^> | NoOp | --^> a   ==>   y --^> | a |
  //    ...    |      |                  ...  |   |
  //    z --^> +------+                z --^> +---+
  //
  // Case b)
  //           +------+ --^> a         +---+ --^> a
  //    x --^> | NoOp | --^> b  ==>    | x | --^> b
  //           |      | ...            |   | ...
  //           +------+ --^> c         +---+ --^> c
  // Case c)
  //           +------+                x ---^> a
  //    x --^> | NoOp | --^> a  ==>      \/
  //    y --^> |      | --^> b           /\
  //           +------+                y ---^> b
  //
  // We only apply this optimization if we don't increase the number of control
  // edges across device boundaries, e.g. in cases a) and b) if NoOp and
  // a and x, respectively, are on the same device. Control edges across device
  // boundaries require inter-device communication (Send/Recv pairs to be
  // inserted in the graph), which is very costly.
  //
  // We also remove identity nodes, subject to the same constraints on number of
  // resulting control edges and device boundary crossings:
  //
  // Case a)
  //          +----------+ ---> a       +---+ ---> a
  //    x --> | Identity | --^> b  ==>  | x | --^> b
  //          |          | ...          |   | ...
  //          +----------+ --^> c       +---+ --^> c
  //
  // Case b)
  //    x ---> +----------+ ---> a      x ---> +---+
  //    y --^> | Identity |        ==>  y --^> | a |
  //    ...    |          |               ...  |   |
  //    z --^> +----------+             z --^> +---+
  //
  // Case c)
  //           +----------+             x ---> +---+
  //    x ---> | Identity | ---> a ==>   \--^> | a |
  //    y --^> |          | --^> b       /\    +---+
  //           +----------+             y --^> b

  if (is_noop || ((is_identity || is_multi_input_identity) &&
                  SafeToRemoveIdentity(*node))) {
    const int num_inputs = node->input_size();
    std::vector<NodeDef*> input_nodes;
    for (int i = 0; i < num_inputs; ++i) {
      NodeDef* input_node = node_map_->GetNode(node->input(i));
      if (input_node == nullptr) {
        LOG(ERROR) << "Invalid input " << node->input(i);
        return;
      }
      input_nodes.push_back(input_node);
    }
    const auto& output_node_set = node_map_->GetOutputs(node_name);
    const std::vector<NodeDef*> output_nodes(output_node_set.begin(),
                                             output_node_set.end());

    if (!BypassingNodeIsBeneficial(*node, input_nodes, output_nodes)) {
      return;
    }

    VLOG(2) << "***** Rerouting input around\n" << node->DebugString();
    // Now remove the node and re-wire its inputs to its outputs.
    for (auto consumer : output_nodes) {
      bool updated_consumer = false;
      VLOG(2) << "consumer before:\n" << consumer->DebugString();
      // Remove dependency on node from consumer.
      for (int i = 0; i < num_inputs; ++i) {
        const NodeDef* input = input_nodes[i];
        // Forward dependency from input to consumer if it doesn't already
        // depend on it.
        if ((is_identity && i == 0) ||
            (is_multi_input_identity && !IsControlInput(node->input(i)))) {
          // Replace regular input from Identity node.
          string new_input;
          const string& input_to_forward = node->input(i);
          CHECK(!IsControlInput(input_to_forward));
          for (int j = 0; j < consumer->input_size(); ++j) {
            const TensorId old_input = ParseTensorName(consumer->input(j));
            if (old_input.node() == node_name) {
              if (old_input.index() == i) {
                // Regular input
                new_input = input_to_forward;
                node_map_->UpdateInput(consumer->name(),
                                       string(old_input.node()), new_input);
                consumer->set_input(j, new_input);
              } else if (old_input.index() == -1) {
                // Control dependency
                new_input = AsControlDependency(NodeName(input_to_forward));
                node_map_->UpdateInput(consumer->name(),
                                       string(old_input.node()), new_input);
                consumer->set_input(j, new_input);
              }
            }
          }
          updated_consumer = true;
        } else {
          // Forward dependency from input to consumer if it doesn't already
          // depend on it.
          if (node_map_->GetOutputs(input->name()).count(consumer) == 0) {
            consumer->add_input(AsControlDependency(input->name()));
            node_map_->AddOutput(input->name(), consumer->name());
            nodes_to_simplify->PushBack(node_to_idx_[input]);
            updated_consumer = true;
          }
        }
      }
      updated_consumer |= RemoveControlInput(
          consumer, AsControlDependency(node_name), node_map_.get());
      if (updated_consumer) {
        nodes_to_simplify->PushBack(node_to_idx_[consumer]);
      }
      VLOG(2) << "consumer after:\n" << consumer->DebugString();
    }
    node_map_->RemoveOutputs(node_name);
    if (fetch_nodes_known_ &&
        nodes_to_preserve_.find(node_name) == nodes_to_preserve_.end()) {
      // Mark the node for deletion.
      nodes_to_delete->insert(node_idx);

      // Disconnect the node from its inputs to enable further optimizations.
      node_map_->RemoveInputs(node_name);
      node->clear_input();
    }
  }
}


void DependencyOptimizer::GroupCrossDeviceControlEdges(bool host_granularity) {
  VLOG(1)
      << "DependencyOptimizer::GroupCrossDeviceControlEdges host_granularity="
      << host_granularity;
  const int num_nodes = optimized_graph_->node_size();
  for (int i = 0; i < num_nodes; ++i) {
    NodeDef* node = optimized_graph_->mutable_node(i);
    if (node->device().empty()) continue;
    string rest, node_device = node->device();
    if (host_granularity) {
      DeviceNameUtils::SplitDeviceName(node->device(), &node_device, &rest);
    }

    // Creates new noop nodes for devices on which multiple control inputs are
    // located.

    // Map keyed by device name to the newly introduced Noop node for that
    // device. A nullptr value means that we have only seen a single node on
    // that device.
    std::map<string, NodeDef*> noops;
    int num_noops = 0;
    for (int j = 0; j < node->input_size(); ++j) {
      if (IsControlInput(node->input(j))) {
        const NodeDef* input = node_map_->GetNode(node->input(j));
        if (input == nullptr || input->device().empty()) continue;
        string input_device = input->device();
        if (host_granularity) {
          DeviceNameUtils::SplitDeviceName(input->device(), &input_device,
                                           &rest);
        }
        if (input_device != node_device) {
          VLOG(2) << "Cross-device " << node->name() << " " << input->device()
                  << " -> " << node->device();
          auto emplace_result = noops.emplace(input_device, nullptr);
          if (!emplace_result.second &&
              emplace_result.first->second == nullptr) {
            VLOG(2) << "Duplicate input device from " << node->name();
            // This is the second cross-device control input from the same
            // device. Creates an intermediate noop node on that device.
            string group_name;
            NodeDef* noop;
            // Creates a fresh node name; there may be conflicting names from
            // a previous iteration of the optimizer.
            do {
              group_name = AddPrefixToNodeName(
                  node->name(),
                  strings::StrCat("GroupCrossDeviceControlEdges_", num_noops));
              noop = node_map_->GetNode(group_name);
              ++num_noops;
            } while (noop != nullptr);
            noop = optimized_graph_->add_node();
            noop->set_name(group_name);
            noop->set_device(input->device());
            noop->set_op("NoOp");
            node_map_->AddNode(noop->name(), noop);
            emplace_result.first->second = noop;
            VLOG(1) << "GroupCrossDeviceControlEdges: Added "
                    << SummarizeNodeDef(*noop);
          }
        }
      }
    }

    // Reroute existing control edges to go via the newly introduced NoOp nodes.
    int pos = 0;
    while (pos < node->input_size()) {
      const string& input_name = node->input(pos);
      if (IsControlInput(input_name)) {
        NodeDef* input = node_map_->GetNode(input_name);
        if (input == nullptr) {
          ++pos;
        } else {
          string input_device = input->device();
          if (host_granularity) {
            DeviceNameUtils::SplitDeviceName(input->device(), &input_device,
                                             &rest);
          }
          auto it = noops.find(input_device);
          if (it == noops.end() || it->second == nullptr) {
            ++pos;
          } else {
            VLOG(2) << "Rewriting input from " << input_name;
            node->mutable_input()->SwapElements(pos, node->input_size() - 1);
            node->mutable_input()->RemoveLast();
            it->second->add_input(AsControlDependency(*input));
            node_map_->UpdateOutput(input_name, node->name(),
                                    it->second->name());
          }
        }
      } else {
        ++pos;
      }
    }
    for (const auto& entry : noops) {
      if (entry.second) {
        node->add_input(AsControlDependency(*entry.second));
        node_map_->AddOutput(entry.second->name(), node->name());
      }
    }
  }
}


void DependencyOptimizer::CleanControlInputs() {
  for (int i = 0; i < optimized_graph_->node_size(); ++i) {
    DedupControlInputs(optimized_graph_->mutable_node(i));
  }
}


bool DependencyOptimizer::BypassingNodeIsBeneficial(
    const NodeDef& node, const std::vector<NodeDef*>& input_nodes,
    const std::vector<NodeDef*>& output_nodes) const {
  const bool is_identity = IsIdentity(node) || IsIdentityNSingleInput(node);
  const bool is_multi_input_identity_n =
      IsIdentityN(node) && !IsIdentityNSingleInput(node);
  const int num_outputs = output_nodes.size();
  const int num_inputs = node.input_size();

  if (NumEdgesIfBypassed(node, output_nodes) > num_inputs + num_outputs) {
    return false;
  }

  // Make sure that we don't increase the number of edges that cross
  // device boundaries.
  if ((num_inputs == 1 && num_outputs > 1 &&
       input_nodes[0]->device() != node.device()) ||
      (num_inputs > 1 && num_outputs == 1 &&
       output_nodes[0]->device() != node.device())) {
    return false;
  }

  // TODO(rmlarsen): Not all device crossings are equally expensive.
  // Assign a cost to each based on device affinity and compute a
  // cost before and after.
  const string& node_dev = node.device();
  int num_cross_in = 0;
  for (NodeDef* input_node : input_nodes) {
    num_cross_in += static_cast<int>(input_node->device() != node_dev);
  }
  int num_cross_out = 0;
  for (NodeDef* output_node : output_nodes) {
    num_cross_out += static_cast<int>(output_node->device() != node_dev);
  }

  // Make sure we do not increase the number of device crossings.
  const int num_cross_before = num_cross_in + num_cross_out;
  int num_cross_after = 0;
  for (NodeDef* input_node : input_nodes) {
    for (NodeDef* output_node : output_nodes) {
      num_cross_after +=
          static_cast<int>(input_node->device() != output_node->device());
    }
  }
  if (num_cross_after > num_cross_before) {
    return false;
  }

  if ((is_identity || is_multi_input_identity_n) && num_cross_in > 0 &&
      num_cross_out > 0 && num_cross_after > 0) {
    // This identity node follows a device crossing, so it might be
    // following a _Recv node after partitioning. Do not remove such nodes,
    // unless they only have consumers on the same device as themselves.
    return false;
  }

  return true;
}


bool DependencyOptimizer::SafeToRemoveIdentity(const NodeDef& node) const {
  if (!IsIdentity(node) && !IsIdentityN(node)) {
    return true;
  }

  if (nodes_to_preserve_.find(node.name()) != nodes_to_preserve_.end()) {
    return false;
  }
  if (!fetch_nodes_known_) {
    // The output values of this node may be needed.
    return false;
  }

  if (node.input_size() < 1) {
    // Node lacks input, is invalid
    return false;
  }

  const NodeDef* input = node_map_->GetNode(NodeName(node.input(0)));
  if (input == nullptr) {
    VLOG(1) << "node = " << node.name() << " input = " << node.input(0);
    return false;
  }
  // Don't remove Identity nodes corresponding to Variable reads or following
  // Recv.
  if (IsVariable(*input) || IsRecv(*input)) {
    return false;
  }
  for (const auto& consumer : node_map_->GetOutputs(node.name())) {
    if (node.input_size() > 1 && (IsRetval(*consumer) || IsMerge(*consumer))) {
      return false;
    }
    if (IsSwitch(*input)) {
      for (const string& consumer_input : consumer->input()) {
        if (consumer_input == AsControlDependency(node.name())) {
          return false;
        }
      }
    }
  }
  return true;
}


Status DependencyOptimizer::Optimize(Cluster* cluster, const GrapplerItem& item,
                                     GraphDef* optimized_graph) {
  optimized_graph_ = optimized_graph;
  *optimized_graph_ = item.graph;
  nodes_to_preserve_ = item.NodesToPreserve();
  fetch_nodes_known_ = !item.fetch.empty();
  CleanControlInputs();

  const int num_iterations = 2;
  for (int iteration = 0; iteration < num_iterations; ++iteration) {
    GRAPPLER_RETURN_IF_DEADLINE_EXCEEDED();
    Status topo_sort_status;
    // Perform topological sort to prepare the graph for transitive reduction.
    topo_sort_status = TopologicalSort(optimized_graph_);
    // Set up index-based graph datastructures to speed up analysis steps below.
    node_map_.reset(new NodeMap(optimized_graph_));
    BuildNodeToIdx();

    if (topo_sort_status.ok()) {
      // Remove redundant control dependencies.
      TF_RETURN_IF_ERROR(TransitiveReduction());
    } else {
      LOG(ERROR) << "Iteration = " << iteration
                 << ", topological sort failed with message: "
                 << topo_sort_status.error_message();
    }
    // Turn nodes with only control outputs into NoOps, prune NoOp and Identity
    // nodes.
    TF_RETURN_IF_ERROR(OptimizeDependencies());

    // Dedup control inputs.
    CleanControlInputs();

    // Merge multiple control edges from the same device.
    GroupCrossDeviceControlEdges(/*host_granularity=*/false);

    // Merge control edges from the same host to reduce RPC traffic.
    GroupCrossDeviceControlEdges(/*host_granularity=*/true);
  }

  return Status::OK();
}


bool DependencyOptimizer::SafeToConvertToNoOp(const NodeDef& node) const {
  if (HasRegularOutputs(node, *node_map_)) {
    // The output values of this node may be needed.
    VLOG(3) << "Not safe to convert '" << node.name()
            << " to NoOp. Node has outputs.";
    return false;
  }
  if (!fetch_nodes_known_) {
    VLOG(3) << "Not safe to convert '" << node.name()
            << " to NoOp. Fetches unknown.";
    return false;
  }
  if (nodes_to_preserve_.find(node.name()) != nodes_to_preserve_.end()) {
    VLOG(3) << "Not safe to convert to NoOp: " << node.name()
            << " is in preserve set.";
    return false;
  }
  if (IsMerge(node) || IsSwitch(node) || ModifiesFrameInfo(node)) {
    VLOG(3) << "Not safe to convert '" << node.name()
            << " to NoOp. Node modifies frame info.";
    return false;
  }
  // Ops reading variables are marked as stateful, but are safe to remove if
  // redundant.
  static const absl::flat_hash_set<string>* gather_ops =
      new absl::flat_hash_set<string>{"Gather", "GatherV2", "GatherNd",
                                      "ResourceGather", "ResourceGatherNd"};
  const bool is_variable_read =
      IsReadVariableOp(node) || IsReadVariablesOp(node) ||
      gather_ops->find(node.op()) != gather_ops->end();
  if (!is_variable_read && !IsFreeOfSideEffect(node)) {
    VLOG(3) << "Not safe to convert '" << node.name()
            << " to NoOp. Node has side effect.";
    return false;
  }
  if (node.op().rfind("Submodel", 0) == 0) {
    return false;
  }
  const OpDef* op_def = nullptr;
  Status status = OpRegistry::Global()->LookUpOpDef(node.op(), &op_def);
  if (!status.ok() || op_def->output_arg_size() == 0) {
    return false;
  }
  const std::unordered_set<string> do_not_rewrite_ops{
      "Assert",     "CheckNumerics",         "_Retval",
      "_Arg",       "_ParallelConcatUpdate", "TPUExecute",
      "TPUCompile", "ControlTrigger"};
  if (do_not_rewrite_ops.find(node.op()) != do_not_rewrite_ops.end()) {
    return false;
  }
  if (!SafeToRemoveIdentity(node)) {
    return false;
  }
  return true;
}


void DependencyOptimizer::BuildNodeToIdx() {
  // Set up &node -> index map.
  node_to_idx_.clear();
  for (int i = 0; i < optimized_graph_->node_size(); ++i) {
    const NodeDef& node = optimized_graph_->node(i);
    node_to_idx_[&node] = i;
  }
}


GF_Err mpgviddmx_process(GF_Filter *filter)
{
	GF_MPGVidDmxCtx *ctx = gf_filter_get_udta(filter);
	GF_FilterPacket *pck, *dst_pck;
	u64 byte_offset;
	s64 vosh_start = -1;
	s64 vosh_end = -1;
	GF_Err e;
	char *data;
	u8 *start;
	u32 pck_size;
	s32 remain;

	//always reparse duration
	if (!ctx->duration.num)
		mpgviddmx_check_dur(filter, ctx);

	pck = gf_filter_pid_get_packet(ctx->ipid);
	if (!pck) {
		if (gf_filter_pid_is_eos(ctx->ipid)) {
			mpgviddmx_enqueue_or_dispatch(ctx, NULL, GF_TRUE, GF_TRUE);
			if (ctx->opid)
				gf_filter_pid_set_eos(ctx->opid);
			if (ctx->src_pck) gf_filter_pck_unref(ctx->src_pck);
			ctx->src_pck = NULL;
			return GF_EOS;
		}
		return GF_OK;
	}

	data = (char *) gf_filter_pck_get_data(pck, &pck_size);
	byte_offset = gf_filter_pck_get_byte_offset(pck);

	start = data;
	remain = pck_size;

	//input pid sets some timescale - we flushed pending data , update cts
	if (!ctx->resume_from && ctx->timescale) {
		u64 ts = gf_filter_pck_get_cts(pck);
		if (ts != GF_FILTER_NO_TS) {
			if (!ctx->cts || !ctx->recompute_cts)
				ctx->cts = ts;
		}
		ts = gf_filter_pck_get_dts(pck);
		if (ts != GF_FILTER_NO_TS) {
			if (!ctx->dts || !ctx->recompute_cts)
				ctx->dts = ts;

			if (!ctx->prev_dts) ctx->prev_dts = ts;
			else if (ctx->prev_dts != ts) {
				u64 diff = ts;
				diff -= ctx->prev_dts;
				if (!ctx->cur_fps.den) ctx->cur_fps.den = (u32) diff;
				else if (ctx->cur_fps.den > diff)
					ctx->cur_fps.den = (u32) diff;
			}
		}
		gf_filter_pck_get_framing(pck, &ctx->input_is_au_start, &ctx->input_is_au_end);
		//this will force CTS recomput of each frame
		if (ctx->recompute_cts) ctx->input_is_au_start = GF_FALSE;
		if (ctx->src_pck) gf_filter_pck_unref(ctx->src_pck);
		ctx->src_pck = pck;
		gf_filter_pck_ref_props(&ctx->src_pck);
	}

	//we stored some data to find the complete vosh, aggregate this packet with current one
	if (!ctx->resume_from && ctx->hdr_store_size) {
		if (ctx->hdr_store_alloc < ctx->hdr_store_size + pck_size) {
			ctx->hdr_store_alloc = ctx->hdr_store_size + pck_size;
			ctx->hdr_store = gf_realloc(ctx->hdr_store, sizeof(char)*ctx->hdr_store_alloc);
		}
		memcpy(ctx->hdr_store + ctx->hdr_store_size, data, sizeof(char)*pck_size);
		if (byte_offset != GF_FILTER_NO_BO) {
			if (byte_offset >= ctx->hdr_store_size)
				byte_offset -= ctx->hdr_store_size;
			else
				byte_offset = GF_FILTER_NO_BO;
		}
		ctx->hdr_store_size += pck_size;
		start = data = ctx->hdr_store;
		remain = pck_size = ctx->hdr_store_size;
	}

	if (ctx->resume_from) {
		if (gf_filter_pid_would_block(ctx->opid))
			return GF_OK;

		//resume from data copied internally
		if (ctx->hdr_store_size) {
			assert(ctx->resume_from <= ctx->hdr_store_size);
			start = data = ctx->hdr_store + ctx->resume_from;
			remain = pck_size = ctx->hdr_store_size - ctx->resume_from;
		} else {
			assert(remain >= (s32) ctx->resume_from);
			start += ctx->resume_from;
			remain -= ctx->resume_from;
		}
		ctx->resume_from = 0;
	}

	if (!ctx->bs) {
		ctx->bs = gf_bs_new(start, remain, GF_BITSTREAM_READ);
	} else {
		gf_bs_reassign_buffer(ctx->bs, start, remain);
	}
	if (!ctx->vparser) {
		ctx->vparser = gf_m4v_parser_bs_new(ctx->bs, ctx->is_mpg12);
	}

	while (remain) {
		Bool full_frame;
		u8 *pck_data;
		s32 current;
		u8 sc_type, forced_sc_type=0;
		Bool sc_type_forced = GF_FALSE;
		Bool skip_pck = GF_FALSE;
		u8 ftype;
		u32 tinc;
		u64 size=0;
		u64 fstart;
		Bool is_coded;
		u32 bytes_from_store = 0;
		u32 hdr_offset = 0;
		Bool copy_last_bytes = GF_FALSE;

		//not enough bytes to parse start code
		if (remain<5) {
			memcpy(ctx->hdr_store, start, remain);
			ctx->bytes_in_header = remain;
			break;
		}
		current = -1;

		//we have some potential bytes of a start code in the store, copy some more bytes and check if valid start code.
		//if not, dispatch these bytes as continuation of the data
		if (ctx->bytes_in_header) {

			memcpy(ctx->hdr_store + ctx->bytes_in_header, start, 8 - ctx->bytes_in_header);
			current = mpgviddmx_next_start_code(ctx->hdr_store, 8);

			//no start code in stored buffer
			if ((current<0) || (current >= (s32) ctx->bytes_in_header) )  {
				if (ctx->opid) {
					dst_pck = gf_filter_pck_new_alloc(ctx->opid, ctx->bytes_in_header, &pck_data);
					if (!dst_pck) return GF_OUT_OF_MEM;

					if (ctx->src_pck) gf_filter_pck_merge_properties(ctx->src_pck, dst_pck);
					gf_filter_pck_set_cts(dst_pck, GF_FILTER_NO_TS);
					gf_filter_pck_set_dts(dst_pck, GF_FILTER_NO_TS);
					memcpy(pck_data, ctx->hdr_store, ctx->bytes_in_header);
					gf_filter_pck_set_framing(dst_pck, GF_FALSE, GF_FALSE);

					if (byte_offset != GF_FILTER_NO_BO) {
						gf_filter_pck_set_byte_offset(dst_pck, byte_offset - ctx->bytes_in_header);
					}

					mpgviddmx_enqueue_or_dispatch(ctx, dst_pck, GF_FALSE, GF_FALSE);
				}

				if (current<0) current = -1;
				else current -= ctx->bytes_in_header;
				ctx->bytes_in_header = 0;
			} else {
				//we have a valid start code, check which byte in our store or in the packet payload is the start code type
				//and remember its location to reinit the parser from there
				hdr_offset = 4 - ctx->bytes_in_header + current;
				//bytes still to dispatch
				bytes_from_store = ctx->bytes_in_header;
				ctx->bytes_in_header = 0;
				if (!hdr_offset) {
					forced_sc_type = ctx->hdr_store[current+3];
				} else {
					forced_sc_type = start[hdr_offset-1];
				}
				sc_type_forced = GF_TRUE;
			}
		}
		//no starcode in store, look for startcode in packet
		if (current == -1) {
			//locate next start code
			current = mpgviddmx_next_start_code(start, remain);
			//no start code, dispatch the block
			if (current<0) {
				u8 b3, b2, b1;
				if (! ctx->frame_started) {
					GF_LOG(GF_LOG_DEBUG, GF_LOG_MEDIA, ("[MPGVid] no start code in block and no frame started, discarding data\n" ));
					break;
				}
				size = remain;
				b3 = start[remain-3];
				b2 = start[remain-2];
				b1 = start[remain-1];
				//we may have a startcode at the end of the packet, store it and don't dispatch the last 3 bytes !
				if (!b1 || !b2 || !b3) {
					copy_last_bytes = GF_TRUE;
					assert(size >= 3);
					size -= 3;
					ctx->bytes_in_header = 3;
				}

				dst_pck = gf_filter_pck_new_alloc(ctx->opid, (u32) size, &pck_data);
				if (!dst_pck) return GF_OUT_OF_MEM;

				if (ctx->src_pck) gf_filter_pck_merge_properties(ctx->src_pck, dst_pck);
				memcpy(pck_data, start, (size_t) size);
				gf_filter_pck_set_framing(dst_pck, GF_FALSE, GF_FALSE);
				gf_filter_pck_set_cts(dst_pck, GF_FILTER_NO_TS);
				gf_filter_pck_set_dts(dst_pck, GF_FILTER_NO_TS);

				if (byte_offset != GF_FILTER_NO_BO) {
					gf_filter_pck_set_byte_offset(dst_pck, byte_offset);
				}

				mpgviddmx_enqueue_or_dispatch(ctx, dst_pck, GF_FALSE, GF_FALSE);
				if (copy_last_bytes) {
					memcpy(ctx->hdr_store, start+remain-3, 3);
				}
				break;
			}
		}

		assert(current>=0);

		//if we are in the middle of parsing the vosh, skip over bytes remaining from previous obj not parsed
		if ((vosh_start>=0) && current) {
			assert(remain>=current);
			start += current;
			remain -= current;
			current = 0;
		}
		//also skip if no output pid
		if (!ctx->opid && current) {
			assert(remain>=current);
			start += current;
			remain -= current;
			current = 0;
		}
		//dispatch remaining bytes
		if (current>0) {
			//flush remaining
			dst_pck = gf_filter_pck_new_alloc(ctx->opid, current, &pck_data);
			if (!dst_pck) return GF_OUT_OF_MEM;

			if (ctx->src_pck) gf_filter_pck_merge_properties(ctx->src_pck, dst_pck);
			gf_filter_pck_set_cts(dst_pck, GF_FILTER_NO_TS);
			gf_filter_pck_set_dts(dst_pck, GF_FILTER_NO_TS);
			gf_filter_pck_set_framing(dst_pck, GF_FALSE, GF_TRUE);
			//bytes were partly in store, partly in packet
			if (bytes_from_store) {
				if (byte_offset != GF_FILTER_NO_BO) {
					gf_filter_pck_set_byte_offset(dst_pck, byte_offset - bytes_from_store);
				}
				assert(bytes_from_store>=(u32) current);
				bytes_from_store -= current;
				memcpy(pck_data, ctx->hdr_store, current);
			} else {
				//bytes were only in packet
				if (byte_offset != GF_FILTER_NO_BO) {
					gf_filter_pck_set_byte_offset(dst_pck, byte_offset);
				}
				memcpy(pck_data, start, current);
				assert(remain>=current);
				start += current;
				remain -= current;
				current = 0;
			}
			gf_filter_pck_set_carousel_version(dst_pck, 1);

			mpgviddmx_enqueue_or_dispatch(ctx, dst_pck, GF_FALSE, GF_FALSE);
		}

		//not enough bytes to parse start code
		if (remain<5) {
			memcpy(ctx->hdr_store, start, remain);
			ctx->bytes_in_header = remain;
			break;
		}

		//parse headers
		//we have a start code loaded, eg the data packet does not have a full start code at the beginning
		if (sc_type_forced) {
			gf_bs_reassign_buffer(ctx->bs, start + hdr_offset, remain - hdr_offset);
			sc_type = forced_sc_type;
		} else {
			gf_bs_reassign_buffer(ctx->bs, start, remain);
			gf_bs_read_int(ctx->bs, 24);
			sc_type = gf_bs_read_int(ctx->bs, 8);
		}

		if (ctx->is_mpg12) {
			switch (sc_type) {
			case M2V_SEQ_START_CODE:
			case M2V_EXT_START_CODE:
				gf_bs_reassign_buffer(ctx->bs, start, remain);
				e = gf_m4v_parse_config(ctx->vparser, &ctx->dsi);
				//not enough data, accumulate until we can parse the full header
				if (e==GF_EOS) {
					if (vosh_start<0) vosh_start = 0;
					if (data == ctx->hdr_store) {
						memmove(ctx->hdr_store, start, remain);
						ctx->hdr_store_size = remain;
					} else {
						if (ctx->hdr_store_alloc < ctx->hdr_store_size + pck_size - vosh_start) {
							ctx->hdr_store_alloc = (u32) (ctx->hdr_store_size + pck_size - vosh_start);
							ctx->hdr_store = gf_realloc(ctx->hdr_store, sizeof(char)*ctx->hdr_store_alloc);
						}
						memcpy(ctx->hdr_store + ctx->hdr_store_size, data + vosh_start, (size_t) (pck_size - vosh_start) );
						ctx->hdr_store_size += pck_size - (u32) vosh_start;
					}
					gf_filter_pid_drop_packet(ctx->ipid);
					return GF_OK;
				} else if (e != GF_OK) {
					GF_LOG(GF_LOG_ERROR, GF_LOG_MEDIA, ("[MPGVid] Failed to parse VOS header: %s\n", gf_error_to_string(e) ));
				} else {
					mpgviddmx_check_pid(filter, ctx, 0, NULL);
				}
				break;
			case M2V_PIC_START_CODE:
				break;
			default:
				break;
			}

		} else {
			u8 PL;
			switch (sc_type) {
			case M4V_VOS_START_CODE:
				ctx->dsi.VideoPL = (u8) gf_bs_read_u8(ctx->bs);
				vosh_start = start - (u8 *)data;
				skip_pck = GF_TRUE;
				assert(remain>=5);
				start += 5;
				remain -= 5;
				break;
			case M4V_VOL_START_CODE:
				gf_bs_reassign_buffer(ctx->bs, start, remain);
				PL = ctx->dsi.VideoPL;
				e = gf_m4v_parse_config(ctx->vparser, &ctx->dsi);
				ctx->dsi.VideoPL = PL;
				//not enough data, accumulate until we can parse the full header
				if (e==GF_EOS) {
					if (vosh_start<0) vosh_start = 0;
					if (data == ctx->hdr_store) {
						memmove(ctx->hdr_store, start, remain);
						ctx->hdr_store_size = remain;
					} else {
						if (ctx->hdr_store_alloc < ctx->hdr_store_size + pck_size - vosh_start) {
							ctx->hdr_store_alloc = (u32) (ctx->hdr_store_size + pck_size - (u32) vosh_start);
							ctx->hdr_store = gf_realloc(ctx->hdr_store, sizeof(char)*ctx->hdr_store_alloc);
						}
						memcpy(ctx->hdr_store + ctx->hdr_store_size, data + vosh_start, (size_t) (pck_size - vosh_start) );
						ctx->hdr_store_size += pck_size - (u32) vosh_start;
					}
					gf_filter_pid_drop_packet(ctx->ipid);
					return GF_OK;
				} else if (e != GF_OK) {
					GF_LOG(GF_LOG_ERROR, GF_LOG_MEDIA, ("[MPGVid] Failed to parse VOS header: %s\n", gf_error_to_string(e) ));
				} else {
					u32 obj_size = (u32) gf_m4v_get_object_start(ctx->vparser);
					if (vosh_start<0) vosh_start = 0;
					vosh_end = start - (u8 *)data + obj_size;
					vosh_end -= vosh_start;
					mpgviddmx_check_pid(filter, ctx,(u32)  vosh_end, data+vosh_start);
					skip_pck = GF_TRUE;
					assert(remain>=(s32) obj_size);
					start += obj_size;
					remain -= obj_size;
				}
				break;
			case M4V_VOP_START_CODE:
			case M4V_GOV_START_CODE:
				break;

			case M4V_VO_START_CODE:
			case M4V_VISOBJ_START_CODE:
			default:
				if (vosh_start>=0) {
					skip_pck = GF_TRUE;
					assert(remain>=4);
					start += 4;
					remain -= 4;
				}
				break;
			}
		}

		if (skip_pck) {
			continue;
		}

		if (!ctx->opid) {
			assert(remain>=4);
			start += 4;
			remain -= 4;
			continue;
		}

		if (!ctx->is_playing) {
			ctx->resume_from = (u32) ((char *)start -  (char *)data);
			return GF_OK;
		}
		//at this point, we no longer reaggregate packets
		ctx->hdr_store_size = 0;

		if (ctx->in_seek) {
			u64 nb_frames_at_seek = (u64) (ctx->start_range * ctx->cur_fps.num);
			if (ctx->cts + ctx->cur_fps.den >= nb_frames_at_seek) {
				//u32 samples_to_discard = (ctx->cts + ctx->dts_inc) - nb_samples_at_seek;
				ctx->in_seek = GF_FALSE;
			}
		}
		//may happen that after all our checks, only 4 bytes are left, continue to store these 4 bytes
		if (remain<5)
			continue;

		//good to go
		gf_m4v_parser_reset(ctx->vparser, sc_type_forced ? forced_sc_type + 1 : 0);
		size = 0;
		e = gf_m4v_parse_frame(ctx->vparser, &ctx->dsi, &ftype, &tinc, &size, &fstart, &is_coded);
		//true if we strip VO and VISOBJ assert(!fstart);

		//we skipped bytes already in store + end of start code present in packet, so the size of the first object
		//needs adjustement
		if (bytes_from_store) {
			size += bytes_from_store + hdr_offset;
		}

		if ((e == GF_EOS) && !ctx->input_is_au_end) {
			u8 b3 = start[remain-3];
			u8 b2 = start[remain-2];
			u8 b1 = start[remain-1];

			//we may have a startcode at the end of the packet, store it and don't dispatch the last 3 bytes !
			if (!b1 || !b2 || !b3) {
				copy_last_bytes = GF_TRUE;
				assert(size >= 3);
				size -= 3;
				ctx->bytes_in_header = 3;
			}
			full_frame = GF_FALSE;
		} else {
			full_frame = GF_TRUE;
		}

		if (!is_coded) {
			/*if prev is B and we're parsing a packed bitstream discard n-vop*/
			if (ctx->forced_packed && ctx->b_frames) {
				ctx->is_packed = GF_TRUE;
				assert(remain>=size);
				start += size;
				remain -= (s32) size;
				continue;
			}
			/*policy is to import at variable frame rate, skip*/
			if (ctx->vfr) {
				ctx->is_vfr = GF_TRUE;
				mpgviddmx_update_time(ctx);
				assert(remain>=size);
				start += size;
				remain -= (s32) size;
				continue;
			}
			/*policy is to keep non coded frame (constant frame rate), add*/
		}

		if (ftype==2) {
			//count number of B-frames since last ref
			ctx->b_frames++;
			ctx->nb_b++;
		} else {
			//flush all pending packets
			mpgviddmx_enqueue_or_dispatch(ctx, NULL, GF_TRUE, GF_FALSE);
			//remeber the CTS of the last ref
			ctx->last_ref_cts = ctx->cts;
			if (ctx->max_b < ctx->b_frames) ctx->max_b = ctx->b_frames;

			ctx->b_frames = 0;
			if (ftype)
				ctx->nb_p++;
			else
				ctx->nb_i++;
		}
		ctx->nb_frames++;

		dst_pck = gf_filter_pck_new_alloc(ctx->opid, (u32) size, &pck_data);
		if (!dst_pck) return GF_OUT_OF_MEM;

		if (ctx->src_pck) gf_filter_pck_merge_properties(ctx->src_pck, dst_pck);
		//bytes come from both our store and the data packet
		if (bytes_from_store) {
			memcpy(pck_data, ctx->hdr_store+current, bytes_from_store);
			assert(size >= bytes_from_store);
			size -= bytes_from_store;
			if (byte_offset != GF_FILTER_NO_BO) {
				gf_filter_pck_set_byte_offset(dst_pck, byte_offset - bytes_from_store);
			}
			memcpy(pck_data + bytes_from_store, start, (size_t) size);
		} else {
			//bytes only come the data packet
			memcpy(pck_data, start, (size_t) size);
			if (byte_offset != GF_FILTER_NO_BO) {
				gf_filter_pck_set_byte_offset(dst_pck, byte_offset + start - (u8 *) data);
			}
		}
		assert(pck_data[0] == 0);
		assert(pck_data[1] == 0);
		assert(pck_data[2] == 0x01);

		gf_filter_pck_set_framing(dst_pck, GF_TRUE, (full_frame || ctx->input_is_au_end) ? GF_TRUE : GF_FALSE);
		gf_filter_pck_set_cts(dst_pck, ctx->cts);
		gf_filter_pck_set_dts(dst_pck, ctx->dts);
		if (ctx->input_is_au_start) {
			ctx->input_is_au_start = GF_FALSE;
		} else {
			//we use the carousel flag temporarly to indicate the cts must be recomputed
			gf_filter_pck_set_carousel_version(dst_pck, 1);
		}
		gf_filter_pck_set_sap(dst_pck, ftype ? GF_FILTER_SAP_NONE : GF_FILTER_SAP_1);
		gf_filter_pck_set_duration(dst_pck, ctx->cur_fps.den);
		if (ctx->in_seek) gf_filter_pck_set_seek_flag(dst_pck, GF_TRUE);
		ctx->frame_started = GF_TRUE;

		mpgviddmx_enqueue_or_dispatch(ctx, dst_pck, GF_FALSE, GF_FALSE);

		mpgviddmx_update_time(ctx);

		if (!full_frame) {
			if (copy_last_bytes) {
				memcpy(ctx->hdr_store, start+remain-3, 3);
			}
			break;
		}
		assert(remain>=size);
		start += size;
		remain -= (s32) size;
	}
	gf_filter_pid_drop_packet(ctx->ipid);

	return GF_OK;
}

fixed #1905


const GF_FilterRegister *mpgviddmx_register(GF_FilterSession *session)
{
	return &MPGVidDmxRegister;
}

fixed #1905


static s32 mpgviddmx_next_start_code(u8 *data, u32 size)
{
	u32 v, bpos, found;
	s64 start, end;

	bpos = 0;
	found = 0;
	start = 0;
	end = 0;

	v = 0xffffffff;
	while (!end) {
		if (bpos == size)
			return -1;
		v = ( (v<<8) & 0xFFFFFF00) | data[bpos];

		bpos++;
		if ((v & 0xFFFFFF00) == 0x00000100) {
			end = start + bpos - 4;
			found = 1;
			break;
		}
	}
	if (!found)
		return -1;
	assert(end >= start);
	return (s32) (end - start);
}

fixed #1905


static GFINLINE void mpgviddmx_update_time(GF_MPGVidDmxCtx *ctx)
{
	assert(ctx->cur_fps.num);

	if (ctx->timescale) {
		u64 inc = 3000;
		if (ctx->cur_fps.den && ctx->cur_fps.num) {
			inc = ctx->cur_fps.den;
			if (ctx->cur_fps.num != ctx->timescale) {
				inc *= ctx->timescale;
				inc /= ctx->cur_fps.num;
			}
		}
		ctx->cts += inc;
		ctx->dts += inc;
	} else {
		assert(ctx->cur_fps.den);
		ctx->cts += ctx->cur_fps.den;
		ctx->dts += ctx->cur_fps.den;
	}
}

fixed #1905


static void mpgviddmx_finalize(GF_Filter *filter)
{
	GF_MPGVidDmxCtx *ctx = gf_filter_get_udta(filter);
	if (ctx->bs) gf_bs_del(ctx->bs);
	if (ctx->vparser) gf_m4v_parser_del_no_bs(ctx->vparser);
	if (ctx->indexes) gf_free(ctx->indexes);
	if (ctx->hdr_store) gf_free(ctx->hdr_store);
	if (ctx->pck_queue) {
		while (gf_list_count(ctx->pck_queue)) {
			GF_FilterPacket *pck = gf_list_pop_back(ctx->pck_queue);
			gf_filter_pck_discard(pck);
		}
		gf_list_del(ctx->pck_queue);
	}
	if (ctx->src_pck) gf_filter_pck_unref(ctx->src_pck);
	if (ctx->importer) {
		GF_LOG(GF_LOG_INFO, GF_LOG_AUTHOR, ("%s Import results: %d VOPs (%d Is - %d Ps - %d Bs)\n", ctx->is_mpg12 ? "MPEG-1/2" : "MPEG-4 (Part 2)", ctx->nb_frames, ctx->nb_i, ctx->nb_p, ctx->nb_b));
		if (ctx->nb_b) {
			GF_LOG(GF_LOG_INFO, GF_LOG_AUTHOR, ("\t%d max consecutive B-frames%s\n", ctx->max_b, ctx->is_packed ? " - packed bitstream" : "" ));
		}
		if (ctx->is_vfr && ctx->nb_b && ctx->is_packed) {
			GF_LOG(GF_LOG_INFO, GF_LOG_AUTHOR, ("Warning: Mix of non-coded frames: packed bitstream and encoder skiped - unpredictable timing\n"));
		}
	}
}

fixed #1905


const GF_FilterRegister *mpgviddmx_register(GF_FilterSession *session)
{
	return NULL;
}

fixed #1905


static void mpgviddmx_enqueue_or_dispatch(GF_MPGVidDmxCtx *ctx, GF_FilterPacket *pck, Bool flush_ref, Bool is_eos)
{
	//TODO: we are dispatching frames in "negctts mode", ie we may have DTS>CTS
	//need to signal this for consumers using DTS (eg MPEG-2 TS)
	if (flush_ref && ctx->pck_queue) {
		//send all reference packet queued
		u32 i, count = gf_list_count(ctx->pck_queue);

		for (i=0; i<count; i++) {
			u64 cts;
			GF_FilterPacket *q_pck = gf_list_get(ctx->pck_queue, i);
			u8 carousel = gf_filter_pck_get_carousel_version(q_pck);
			if (!carousel) {
				gf_filter_pck_send(q_pck);
				continue;
			}
			gf_filter_pck_set_carousel_version(q_pck, 0);
			cts = gf_filter_pck_get_cts(q_pck);
			if (cts != GF_FILTER_NO_TS) {
				//offset the cts of the ref frame to the number of B frames in-between
				if (ctx->last_ref_cts == cts) {
					cts += ctx->b_frames * ctx->cur_fps.den;
					gf_filter_pck_set_cts(q_pck, cts);
				} else {
					//shift all other frames (i.e. pending Bs) by 1 frame in the past since we move the ref frame after them
					assert(cts >= ctx->cur_fps.den);
					cts -= ctx->cur_fps.den;
					gf_filter_pck_set_cts(q_pck, cts);
				}
			}
			if (is_eos && (i+1==count)) {
				Bool start, end;
				gf_filter_pck_get_framing(q_pck, &start, &end);
				gf_filter_pck_set_framing(q_pck, start, GF_TRUE);
			}
			gf_filter_pck_send(q_pck);
		}
		gf_list_reset(ctx->pck_queue);
	}
	if (!pck) return;

	if (!ctx->pck_queue) ctx->pck_queue = gf_list_new();
	gf_list_add(ctx->pck_queue, pck);
}

fixed #1905


static void mpgviddmx_check_pid(GF_Filter *filter, GF_MPGVidDmxCtx *ctx, u32 vosh_size, u8 *data)
{
	if (!ctx->opid) {
		ctx->opid = gf_filter_pid_new(filter);
		gf_filter_pid_copy_properties(ctx->opid, ctx->ipid);
		mpgviddmx_check_dur(filter, ctx);
	}

	if ((ctx->width == ctx->dsi.width) && (ctx->height == ctx->dsi.height)) return;

	//copy properties at init or reconfig
	gf_filter_pid_set_property(ctx->opid, GF_PROP_PID_STREAM_TYPE, & PROP_UINT(GF_STREAM_VISUAL));
	gf_filter_pid_set_property(ctx->opid, GF_PROP_PID_TIMESCALE, & PROP_UINT(ctx->timescale ? ctx->timescale : ctx->cur_fps.num));
	gf_filter_pid_set_property(ctx->opid, GF_PROP_PID_FPS, & PROP_FRAC(ctx->cur_fps));
	gf_filter_pid_set_property(ctx->opid, GF_PROP_PID_UNFRAMED, NULL);
	if (ctx->duration.num)
		gf_filter_pid_set_property(ctx->opid, GF_PROP_PID_DURATION, & PROP_FRAC64(ctx->duration));

	mpgviddmx_enqueue_or_dispatch(ctx, NULL, GF_TRUE, GF_FALSE);

	ctx->width = ctx->dsi.width;
	ctx->height = ctx->dsi.height;
	gf_filter_pid_set_property(ctx->opid, GF_PROP_PID_WIDTH, & PROP_UINT( ctx->dsi.width));
	gf_filter_pid_set_property(ctx->opid, GF_PROP_PID_HEIGHT, & PROP_UINT( ctx->dsi.height));
	gf_filter_pid_set_property(ctx->opid, GF_PROP_PID_SAR, & PROP_FRAC_INT(ctx->dsi.par_num, ctx->dsi.par_den));

	if (ctx->is_mpg12) {
		const GF_PropertyValue *cid = gf_filter_pid_get_property(ctx->ipid, GF_PROP_PID_CODECID);
		u32 PL = ctx->dsi.VideoPL;
		if (cid) {
			switch (cid->value.uint) {
			case GF_CODECID_MPEG2_MAIN:
			case GF_CODECID_MPEG2_422:
			case GF_CODECID_MPEG2_SNR:
			case GF_CODECID_MPEG2_HIGH:
				//keep same signaling
				PL = cid->value.uint;
				break;
			default:
				break;
			}
		}
		if (!PL) PL = GF_CODECID_MPEG2_MAIN;
		gf_filter_pid_set_property(ctx->opid, GF_PROP_PID_CODECID, & PROP_UINT(PL));
	} else {
		gf_filter_pid_set_property(ctx->opid, GF_PROP_PID_CODECID, & PROP_UINT(GF_CODECID_MPEG4_PART2));
	}
	gf_filter_pid_set_property(ctx->opid, GF_PROP_PID_PROFILE_LEVEL, & PROP_UINT (ctx->dsi.VideoPL) );

	if (ctx->bitrate) {
		gf_filter_pid_set_property(ctx->opid, GF_PROP_PID_BITRATE, & PROP_UINT(ctx->bitrate));
	}

	ctx->b_frames = 0;

	if (vosh_size) {
		u32 i;
		char * dcfg = gf_malloc(sizeof(char)*vosh_size);
		memcpy(dcfg, data, sizeof(char)*vosh_size);

		/*remove packed flag if any (VOSH user data)*/
		ctx->is_packed = ctx->is_vfr = ctx->forced_packed = GF_FALSE;
		i=0;
		while (1) {
			char *frame = dcfg;
			while ((i+3<vosh_size)  && ((frame[i]!=0) || (frame[i+1]!=0) || (frame[i+2]!=1))) i++;
			if (i+4>=vosh_size) break;
			if (strncmp(frame+i+4, "DivX", 4)) {
				i += 4;
				continue;
			}
			frame = memchr(dcfg + i + 4, 'p', vosh_size - i - 4);
			if (frame) {
				ctx->forced_packed = GF_TRUE;
				frame[0] = 'n';
			}
			break;
		}
		gf_filter_pid_set_property(ctx->opid, GF_PROP_PID_DECODER_CONFIG, & PROP_DATA_NO_COPY(dcfg, vosh_size));
	}

	if (ctx->is_file && ctx->index) {
		gf_filter_pid_set_property(ctx->opid, GF_PROP_PID_PLAYBACK_MODE, & PROP_UINT(GF_PLAYBACK_MODE_FASTFORWARD) );
	}
}

fixed #1905


static const char * mpgvdmx_probe_data(const u8 *data, u32 size, GF_FilterProbeScore *score)
{
	GF_M4VParser *parser;
	u8 ftype;
	u32 tinc, nb_frames, o_start=0;
	u64 fsize, start;
	Bool is_coded;
	GF_Err e;
	GF_M4VDecSpecInfo dsi;

	memset(&dsi, 0, sizeof(GF_M4VDecSpecInfo));
	parser = gf_m4v_parser_new((char*)data, size, GF_FALSE);
	nb_frames = 0;
	while (1) {
		u32 otype;
		ftype = 0;
		is_coded = GF_FALSE;
		e = gf_m4v_parse_frame(parser, &dsi, &ftype, &tinc, &fsize, &start, &is_coded);
		if (!nb_frames && start) o_start = (u32) start;

		otype = gf_m4v_parser_get_obj_type(parser);
		switch (otype) {
		case M4V_VOL_START_CODE:
		case M4V_VOP_START_CODE:
		case M4V_VISOBJ_START_CODE:
		case M4V_VOS_START_CODE:
		case M4V_GOV_START_CODE:
		case M4V_UDTA_START_CODE:
			break;
		default:
			otype = 0;
		}

		//if start is more than 4 (start-code size), we have garbage at the beginning, do not parse
		//except if we have a valid object VOS
		if (!nb_frames && (start>4) && !otype) {
			break;
		}
		if (is_coded) nb_frames++;
		if (e==GF_EOS) {
			e = GF_OK;
			//special case if the only frame we have is not coded
			if (otype == M4V_VOP_START_CODE) {
				if (!nb_frames) nb_frames++;
				is_coded = 1;
			}

			if (is_coded) nb_frames++;
			break;
		}
		if (ftype>2) break;
		if (e) break;
		nb_frames++;
	}
	gf_m4v_parser_del(parser);
	if ((e==GF_OK) && (nb_frames>1)) {
		*score = o_start ? GF_FPROBE_MAYBE_NOT_SUPPORTED : GF_FPROBE_MAYBE_SUPPORTED;
		return "video/mp4v-es";
	}

	memset(&dsi, 0, sizeof(GF_M4VDecSpecInfo));
	parser = gf_m4v_parser_new((char*)data, size, GF_TRUE);
	nb_frames = 0;
	while (1) {
		ftype = 0;
		is_coded = GF_FALSE;
		e = gf_m4v_parse_frame(parser, &dsi, &ftype, &tinc, &fsize, &start, &is_coded);

		//if start is more than 4 (start-code size), we have garbage at the beginning, do not parse
		if (!nb_frames && (start>4) ) {
			break;
		}
		if (is_coded) nb_frames++;
		if (e==GF_EOS) {
			if (is_coded) nb_frames++;
			e = GF_OK;
			break;
		}
		if (ftype>2) break;
		if (e) break;
		nb_frames++;
	}
	gf_m4v_parser_del(parser);
	if ((e==GF_OK) && (nb_frames>1)) {
		*score = o_start ? GF_FPROBE_MAYBE_NOT_SUPPORTED : GF_FPROBE_MAYBE_SUPPORTED;
		return "video/mpgv-es";
	}
	return NULL;
}

fixed #1905


static Bool mpgviddmx_process_event(GF_Filter *filter, const GF_FilterEvent *evt)
{
	u32 i;
	u64 file_pos = 0;
	GF_FilterEvent fevt;
	GF_MPGVidDmxCtx *ctx = gf_filter_get_udta(filter);

	switch (evt->base.type) {
	case GF_FEVT_PLAY:
		if (!ctx->is_playing) {
			ctx->is_playing = GF_TRUE;
			ctx->cts = 0;
			ctx->bytes_in_header = 0;
		}
		if (! ctx->is_file) {
			if (!ctx->initial_play_done) {
				ctx->initial_play_done = GF_TRUE;
				if (evt->play.start_range>0.1) ctx->resume_from = 0;
 			}
			return GF_FALSE;
		}
		ctx->start_range = evt->play.start_range;
		ctx->in_seek = GF_TRUE;

		if (ctx->start_range) {
			for (i=1; i<ctx->index_size; i++) {
				if ((ctx->indexes[i].start_time > ctx->start_range) || (i+1==ctx->index_size)) {
					ctx->cts = (u64) (ctx->indexes[i-1].start_time * ctx->cur_fps.num);
					file_pos = ctx->indexes[i-1].pos;
					break;
				}
			}
		}
		ctx->dts = ctx->cts;
		if (!ctx->initial_play_done) {
			ctx->initial_play_done = GF_TRUE;
			//seek will not change the current source state, don't send a seek
			if (!file_pos)
				return GF_TRUE;
		}
		ctx->resume_from = 0;
		ctx->bytes_in_header = 0;
		//post a seek
		GF_FEVT_INIT(fevt, GF_FEVT_SOURCE_SEEK, ctx->ipid);
		fevt.seek.start_offset = file_pos;
		gf_filter_pid_send_event(ctx->ipid, &fevt);

		//cancel event
		return GF_TRUE;

	case GF_FEVT_STOP:
		ctx->is_playing = GF_FALSE;
		if (ctx->src_pck) gf_filter_pck_unref(ctx->src_pck);
		ctx->src_pck = NULL;
		if (ctx->pck_queue) {
			while (gf_list_count(ctx->pck_queue)) {
				GF_FilterPacket *pck=gf_list_pop_front(ctx->pck_queue);
				gf_filter_pck_discard(pck);
			}
		}
		//don't cancel event
		return GF_FALSE;

	case GF_FEVT_SET_SPEED:
		//cancel event
		return GF_TRUE;
	default:
		break;
	}
	//by default don't cancel event - to rework once we have downloading in place
	return GF_FALSE;
}

fixed #1905


static void mpgviddmx_check_dur(GF_Filter *filter, GF_MPGVidDmxCtx *ctx)
{

	FILE *stream;
	GF_BitStream *bs;
	GF_M4VParser *vparser;
	GF_M4VDecSpecInfo dsi;
	GF_Err e;
	u64 duration, cur_dur, rate;
	const GF_PropertyValue *p;
	if (!ctx->opid || ctx->timescale || ctx->file_loaded) return;

	if (ctx->index<=0) {
		ctx->file_loaded = GF_TRUE;
		return;
	}

	p = gf_filter_pid_get_property(ctx->ipid, GF_PROP_PID_FILEPATH);
	if (!p || !p->value.string || !strncmp(p->value.string, "gmem://", 7)) {
		ctx->is_file = GF_FALSE;
		ctx->file_loaded = GF_TRUE;
		return;
	}
	ctx->is_file = GF_TRUE;

	stream = gf_fopen(p->value.string, "rb");
	if (!stream) return;

	ctx->index_size = 0;

	bs = gf_bs_from_file(stream, GF_BITSTREAM_READ);

	vparser = gf_m4v_parser_bs_new(bs, ctx->is_mpg12);
	e = gf_m4v_parse_config(vparser, &dsi);
	if (e) {
		GF_LOG(GF_LOG_ERROR, GF_LOG_MEDIA, ("[MPGVid] Could not parse video header - duration  not estimated\n"));
		ctx->file_loaded = GF_TRUE;
		return;
	}

	duration = 0;
	cur_dur = 0;
	while (gf_bs_available(bs)) {
		u8 ftype;
		u32 tinc;
		u64 fsize, start;
		Bool is_coded;
		u64 pos;
		pos = gf_m4v_get_object_start(vparser);
		e = gf_m4v_parse_frame(vparser, &dsi, &ftype, &tinc, &fsize, &start, &is_coded);
		if (e<0) {
			GF_LOG(GF_LOG_ERROR, GF_LOG_MEDIA, ("[MPGVid] Could not parse video frame\n"));
			continue;
		}

		duration += ctx->cur_fps.den;
		cur_dur += ctx->cur_fps.den;
		//only index at I-frame start
		if (pos && (ftype==0) && (cur_dur >= ctx->index * ctx->cur_fps.num) ) {
			if (!ctx->index_alloc_size) ctx->index_alloc_size = 10;
			else if (ctx->index_alloc_size == ctx->index_size) ctx->index_alloc_size *= 2;
			ctx->indexes = gf_realloc(ctx->indexes, sizeof(MPGVidIdx)*ctx->index_alloc_size);
			ctx->indexes[ctx->index_size].pos = pos;
			ctx->indexes[ctx->index_size].start_time = (Double) (duration-ctx->cur_fps.den);
			ctx->indexes[ctx->index_size].start_time /= ctx->cur_fps.num;
			ctx->index_size ++;
			cur_dur = 0;
		}
	}
	rate = gf_bs_get_position(bs);
	gf_m4v_parser_del(vparser);
	gf_fclose(stream);

	if (!ctx->duration.num || (ctx->duration.num  * ctx->cur_fps.num != duration * ctx->duration.den)) {
		ctx->duration.num = (s32) duration;
		ctx->duration.den = ctx->cur_fps.num;

		gf_filter_pid_set_property(ctx->opid, GF_PROP_PID_DURATION, & PROP_FRAC64(ctx->duration));

		if (duration && !gf_sys_is_test_mode() ) {
			rate *= 8 * ctx->duration.den;
			rate /= ctx->duration.num;
			ctx->bitrate = (u32) rate;
		}
	}

	p = gf_filter_pid_get_property(ctx->ipid, GF_PROP_PID_FILE_CACHED);
	if (p && p->value.boolean) ctx->file_loaded = GF_TRUE;
	gf_filter_pid_set_property(ctx->opid, GF_PROP_PID_CAN_DATAREF, & PROP_BOOL(GF_TRUE ) );
}

fixed #1905


static GF_Err mpgviddmx_initialize(GF_Filter *filter)
{
	GF_MPGVidDmxCtx *ctx = gf_filter_get_udta(filter);
	ctx->hdr_store_size = 0;
	ctx->hdr_store_alloc = 8;
	ctx->hdr_store = gf_malloc(sizeof(char)*8);
	return GF_OK;
}

fixed #1905


GF_Err mpgviddmx_configure_pid(GF_Filter *filter, GF_FilterPid *pid, Bool is_remove)
{
	Bool was_mpeg12;
	const GF_PropertyValue *p;
	GF_MPGVidDmxCtx *ctx = gf_filter_get_udta(filter);

	if (is_remove) {
		ctx->ipid = NULL;
		if (ctx->opid) {
			gf_filter_pid_remove(ctx->opid);
			ctx->opid = NULL;
		}
		return GF_OK;
	}
	if (! gf_filter_pid_check_caps(pid))
		return GF_NOT_SUPPORTED;

	ctx->ipid = pid;
	ctx->cur_fps = ctx->fps;
	if (!ctx->fps.num || !ctx->fps.den) {
		ctx->cur_fps.num = 25000;
		ctx->cur_fps.den = 1000;
	}

	p = gf_filter_pid_get_property(pid, GF_PROP_PID_TIMESCALE);
	if (p) {
		ctx->timescale = ctx->cur_fps.num = p->value.uint;
		ctx->cur_fps.den = 0;
		p = gf_filter_pid_get_property(pid, GF_PROP_PID_FPS);
		if (p) {
			ctx->cur_fps = p->value.frac;
		}
		p = gf_filter_pid_get_property_str(pid, "nocts");
		if (p && p->value.boolean) ctx->recompute_cts = GF_TRUE;
	}

	was_mpeg12 = ctx->is_mpg12;

	p = gf_filter_pid_get_property(pid, GF_PROP_PID_CODECID);
	if (p) {
		switch (p->value.uint) {
		case GF_CODECID_MPEG1:
		case GF_CODECID_MPEG2_422:
		case GF_CODECID_MPEG2_SNR:
		case GF_CODECID_MPEG2_HIGH:
		case GF_CODECID_MPEG2_MAIN:
		case GF_CODECID_MPEG2_SIMPLE:
		case GF_CODECID_MPEG2_SPATIAL:
			ctx->is_mpg12 = GF_TRUE;
			break;
		}
	}
	else {
		p = gf_filter_pid_get_property(pid, GF_PROP_PID_MIME);
		if (p && p->value.string && (strstr(p->value.string, "m1v") || strstr(p->value.string, "m2v")) ) ctx->is_mpg12 = GF_TRUE;
		else {
			p = gf_filter_pid_get_property(pid, GF_PROP_PID_FILE_EXT);
			if (p && p->value.string && (strstr(p->value.string, "m1v") || strstr(p->value.string, "m2v")) ) ctx->is_mpg12 = GF_TRUE;
		}
	}

	if (ctx->vparser && (was_mpeg12 != ctx->is_mpg12)) {
		gf_m4v_parser_del_no_bs(ctx->vparser);
		ctx->vparser = NULL;
	}

	if (ctx->timescale && !ctx->opid) {
		ctx->opid = gf_filter_pid_new(filter);
		gf_filter_pid_copy_properties(ctx->opid, ctx->ipid);
		gf_filter_pid_set_property(ctx->opid, GF_PROP_PID_UNFRAMED, NULL);
	}
	return GF_OK;
}

fixed #1905


OpTypeConstructor UnaryTensorContainer(FullTypeId t, FullTypeId dtype) {
  return [t, dtype](OpDef* op_def) {
    FullTypeDef* tdef =
        op_def->mutable_output_arg(0)->mutable_experimental_full_type();
    tdef->set_type_id(t);

    FullTypeDef* arg = tdef->add_args();
    arg->set_type_id(TFT_TENSOR);
    FullTypeDef* targ = arg->add_args();
    targ->set_type_id(dtype);

    return Status::OK();
  };
}

Prevent null dereference read in `SpecializeType()`

For some adversarial protos, the attribute for a key might not exist.

PiperOrigin-RevId: 408382090
Change-Id: Ie7eabe532c9ff280fce5dce1f6cdb93c76c2e040


OpTypeConstructor UnaryGeneric(FullTypeId t) {
  return [t](OpDef* op_def) {
    FullTypeDef* tdef =
        op_def->mutable_output_arg(0)->mutable_experimental_full_type();
    tdef->set_type_id(t);

    FullTypeDef* arg = tdef->add_args();
    arg->set_type_id(TFT_ANY);

    return Status::OK();
  };
}


OpTypeConstructor Nullary(FullTypeId t) {
  return [t](OpDef* op_def) {
    FullTypeDef* tdef =
        op_def->mutable_output_arg(0)->mutable_experimental_full_type();
    tdef->set_type_id(t);
    return Status::OK();
  };
}


OpTypeConstructor Unary(FullTypeId t, const string& var_name) {
  return [t, var_name](OpDef* op_def) {
    FullTypeDef* tdef =
        op_def->mutable_output_arg(0)->mutable_experimental_full_type();
    tdef->set_type_id(t);

    FullTypeDef* arg = tdef->add_args();
    arg->set_type_id(TFT_VAR);
    arg->set_s(var_name);

    return Status::OK();
  };
}


u32 gf_bs_read_ue_log_idx3(GF_BitStream *bs, const char *fname, s32 idx1, s32 idx2, s32 idx3)
{
	u32 val=0, code;
	s32 nb_lead = -1;
	u32 bits = 0;
	for (code=0; !code; nb_lead++) {
		if (nb_lead>=32) {
			break;
		}
		code = gf_bs_read_int(bs, 1);
		bits++;
	}

	if (nb_lead>=32) {
		//gf_bs_read_int keeps returning 0 on EOS, so if no more bits available, rbsp was truncated otherwise code is broken in rbsp)
		//we only test once nb_lead>=32 to avoid testing at each bit read
		if (!gf_bs_available(bs)) {
			GF_LOG(GF_LOG_ERROR, GF_LOG_CODING, ("[Core] exp-golomb read failed, not enough bits in bitstream !\n"));
		} else {
			GF_LOG(GF_LOG_ERROR, GF_LOG_CODING, ("[Core] corrupted exp-golomb code, %d leading zeros, max 31 allowed !\n", nb_lead));
		}
		return 0;
	}

	if (nb_lead) {
		u32 leads=1;
		val = gf_bs_read_int(bs, nb_lead);
		leads <<= nb_lead;
		leads -= 1;
		val += leads;
//		val += (1 << nb_lead) - 1;
		bits += nb_lead;
	}

	if (fname) {
		gf_bs_log_idx(bs, bits, fname, val, idx1, idx2, idx3);
	}
	return val;
}

fixed #1900


static s32 svc_parse_slice(GF_BitStream *bs, AVCState *avc, AVCSliceInfo *si)
{
	s32 pps_id;

	/*s->current_picture.reference= h->nal_ref_idc != 0;*/
	gf_bs_read_ue_log(bs, "first_mb_in_slice");
	si->slice_type = gf_bs_read_ue_log(bs, "slice_type");
	if (si->slice_type > 9) return -1;

	pps_id = gf_bs_read_ue_log(bs, "pps_id");
	if ((pps_id<0) || (pps_id > 255))
		return -1;
	si->pps = &avc->pps[pps_id];
	si->pps->id = pps_id;
	if (!si->pps->slice_group_count)
		return -2;
	si->sps = &avc->sps[si->pps->sps_id + GF_SVC_SSPS_ID_SHIFT];
	if (!si->sps->log2_max_frame_num)
		return -2;

	si->frame_num = gf_bs_read_int_log(bs, si->sps->log2_max_frame_num, "frame_num");

	si->field_pic_flag = 0;
	if (si->sps->frame_mbs_only_flag) {
		/*s->picture_structure= PICT_FRAME;*/
	}
	else {
		si->field_pic_flag = gf_bs_read_int_log(bs, 1, "field_pic_flag");
		if (si->field_pic_flag) si->bottom_field_flag = gf_bs_read_int_log(bs, 1, "bottom_field_flag");
	}
	if (si->nal_unit_type == GF_AVC_NALU_IDR_SLICE || si->NalHeader.idr_pic_flag)
		si->idr_pic_id = gf_bs_read_ue_log(bs, "idr_pic_id");

	if (si->sps->poc_type == 0) {
		si->poc_lsb = gf_bs_read_int_log(bs, si->sps->log2_max_poc_lsb, "poc_lsb");
		if (si->pps->pic_order_present && !si->field_pic_flag) {
			si->delta_poc_bottom = gf_bs_read_se_log(bs, "delta_poc_bottom");
		}
	}
	else if ((si->sps->poc_type == 1) && !si->sps->delta_pic_order_always_zero_flag) {
		si->delta_poc[0] = gf_bs_read_se_log(bs, "delta_poc0");
		if ((si->pps->pic_order_present == 1) && !si->field_pic_flag)
			si->delta_poc[1] = gf_bs_read_se_log(bs, "delta_poc1");
	}
	if (si->pps->redundant_pic_cnt_present) {
		si->redundant_pic_cnt = gf_bs_read_ue_log(bs, "redundant_pic_cnt");
	}
	return 0;
}

fixed #1900


  void DecodePngV2(OpKernelContext* context, StringPiece input) {
    int channel_bits = (data_type_ == DataType::DT_UINT8) ? 8 : 16;
    png::DecodeContext decode;
    OP_REQUIRES(
        context, png::CommonInitDecode(input, channels_, channel_bits, &decode),
        errors::InvalidArgument("Invalid PNG. Failed to initialize decoder."));

    // Verify that width and height are not too large:
    // - verify width and height don't overflow int.
    // - width can later be multiplied by channels_ and sizeof(uint16), so
    //   verify single dimension is not too large.
    // - verify when width and height are multiplied together, there are a few
    //   bits to spare as well.
    const int width = static_cast<int>(decode.width);
    const int height = static_cast<int>(decode.height);
    const int64_t total_size =
        static_cast<int64_t>(width) * static_cast<int64_t>(height);
    if (width != static_cast<int64_t>(decode.width) || width <= 0 ||
        width >= (1LL << 27) || height != static_cast<int64_t>(decode.height) ||
        height <= 0 || height >= (1LL << 27) || total_size >= (1LL << 29)) {
      OP_REQUIRES(context, false,
                  errors::InvalidArgument("PNG size too large for int: ",
                                          decode.width, " by ", decode.height));
    }

    Tensor* output = nullptr;
    Status status;
    // By the existing API, we support decoding PNG with `DecodeGif` op.
    // We need to make sure to return 4-D shapes when using `DecodeGif`.
    if (op_type_ == "DecodeGif") {
      status = context->allocate_output(
          0, TensorShape({1, height, width, decode.channels}), &output);
    } else {
      status = context->allocate_output(
          0, TensorShape({height, width, decode.channels}), &output);
    }

    if (op_type_ == "DecodeBmp") {
      // TODO(b/171060723): Only DecodeBmp as op_type_ is not acceptable here
      // because currently `decode_(jpeg|png|gif)` ops can decode any one of
      // jpeg, png or gif but not bmp. Similarly, `decode_bmp` cannot decode
      // anything but bmp formats. This behavior needs to be revisited. For more
      // details, please refer to the bug.
      OP_REQUIRES(context, false,
                  errors::InvalidArgument(
                      "Trying to decode PNG format using DecodeBmp op. Use "
                      "`decode_png` or `decode_image` instead."));
    } else if (op_type_ == "DecodeAndCropJpeg") {
      OP_REQUIRES(context, false,
                  errors::InvalidArgument(
                      "DecodeAndCropJpeg operation can run on JPEG only, but "
                      "detected PNG."));
    }

    if (!status.ok()) png::CommonFreeDecode(&decode);
    OP_REQUIRES_OK(context, status);

    if (data_type_ == DataType::DT_UINT8) {
      OP_REQUIRES(
          context,
          png::CommonFinishDecode(
              reinterpret_cast<png_bytep>(output->flat<uint8>().data()),
              decode.channels * width * sizeof(uint8), &decode),
          errors::InvalidArgument("Invalid PNG data, size ", input.size()));
    } else if (data_type_ == DataType::DT_UINT16) {
      OP_REQUIRES(
          context,
          png::CommonFinishDecode(
              reinterpret_cast<png_bytep>(output->flat<uint16>().data()),
              decode.channels * width * sizeof(uint16), &decode),
          errors::InvalidArgument("Invalid PNG data, size ", input.size()));
    } else if (data_type_ == DataType::DT_FLOAT) {
      // `png::CommonFinishDecode` does not support `float`. First allocate
      // uint16 buffer for the image and decode in uint16 (lossless). Wrap the
      // buffer in `unique_ptr` so that we don't forget to delete the buffer.
      std::unique_ptr<uint16[]> buffer(
          new uint16[height * width * decode.channels]);
      OP_REQUIRES(
          context,
          png::CommonFinishDecode(reinterpret_cast<png_bytep>(buffer.get()),
                                  decode.channels * width * sizeof(uint16),
                                  &decode),
          errors::InvalidArgument("Invalid PNG data, size ", input.size()));

      // Convert uint16 image data to desired data type.
      // Use eigen threadpooling to speed up the copy operation.
      const auto& device = context->eigen_device<Eigen::ThreadPoolDevice>();
      TTypes<uint16, 3>::UnalignedConstTensor buf(buffer.get(), height, width,
                                                  decode.channels);
      float scale = 1. / std::numeric_limits<uint16>::max();
      // Fill output tensor with desired dtype.
      output->tensor<float, 3>().device(device) = buf.cast<float>() * scale;
    }
  }

Prevent use after free in `DecodePng` kernel.

We are cleaning up the memory in `decode` and then we are using an `OP_REQUIRES` to check an invariant on the `decode` data.

PiperOrigin-RevId: 409299145
Change-Id: I4eb93aaca52483eb202e89b78df07fbb2f6cb254


GF_Err gf_odf_av1_cfg_write(GF_AV1Config *cfg, u8 **outData, u32 *outSize) {
	GF_Err e;
	GF_BitStream *bs = gf_bs_new(NULL, 0, GF_BITSTREAM_WRITE);
	*outSize = 0;
	*outData = NULL;
	e = gf_odf_av1_cfg_write_bs(cfg, bs);
	if (e == GF_OK)
		gf_bs_get_content(bs, outData, outSize);

	gf_bs_del(bs);
	return e;
}

fixed #1895


GF_DOVIDecoderConfigurationRecord *gf_odf_dovi_cfg_read_bs(GF_BitStream *bs)
{
	GF_DOVIDecoderConfigurationRecord *cfg;
	GF_SAFEALLOC(cfg, GF_DOVIDecoderConfigurationRecord);

	cfg->dv_version_major = gf_bs_read_u8(bs);
	cfg->dv_version_minor = gf_bs_read_u8(bs);
	cfg->dv_profile = gf_bs_read_int(bs, 7);
	cfg->dv_level = gf_bs_read_int(bs, 6);
	cfg->rpu_present_flag = gf_bs_read_int(bs, 1);
	cfg->el_present_flag = gf_bs_read_int(bs, 1);
	cfg->bl_present_flag = gf_bs_read_int(bs, 1);
	{
		int i = 0;
		u32 data[5];
		memset(data, 0, sizeof(data));
		gf_bs_read_data(bs, (char*)data, 20);
		for (i = 0; i < 5; ++i) {
			if (data[i] != 0) {
				GF_LOG(GF_LOG_WARNING, GF_LOG_CONTAINER, ("[odf_cfg] dovi config reserved bytes are not zero\n"));
			}
		}
	}
	return cfg;
}

fixed #1895


GF_Err gf_odf_vvc_cfg_write(GF_VVCConfig *cfg, u8 **outData, u32 *outSize)
{
	GF_Err e;
	GF_BitStream *bs = gf_bs_new(NULL, 0, GF_BITSTREAM_WRITE);
	*outSize = 0;
	*outData = NULL;
	e = gf_odf_vvc_cfg_write_bs(cfg, bs);
	if (e==GF_OK)
		gf_bs_get_content(bs, outData, outSize);

	gf_bs_del(bs);
	return e;
}

fixed #1895


GF_Err gf_odf_parse_descriptor(GF_BitStream *bs, GF_Descriptor **desc, u32 *desc_size)
{
	u32 val, size, sizeHeader;
	u8 tag;
	GF_Err err;
	GF_Descriptor *newDesc;
	if (!bs) return GF_BAD_PARAM;

	*desc_size = 0;

	//tag
	tag = (u8) gf_bs_read_int(bs, 8);
	sizeHeader = 1;

	//size
	size = 0;
	do {
		val = gf_bs_read_int(bs, 8);
		sizeHeader++;
		if (sizeHeader > 5) {
			GF_LOG(GF_LOG_ERROR, GF_LOG_CODEC, ("[ODF] Descriptor size on more than 4 bytes\n"));
			return GF_ODF_INVALID_DESCRIPTOR;
		}
		size <<= 7;
		size |= val & 0x7F;
	} while ( val & 0x80);
	*desc_size = size;

	if (gf_bs_available(bs) < size) {
		GF_LOG(GF_LOG_ERROR, GF_LOG_CODEC, ("[ODF] Not enough bytes (%d) to read descriptor (size=%d)\n", gf_bs_available(bs), size));
		return GF_ODF_INVALID_DESCRIPTOR;
	}

	GF_LOG(GF_LOG_DEBUG, GF_LOG_CODEC, ("[ODF] Reading descriptor (tag %d size %d)\n", tag, size ));

	newDesc = gf_odf_create_descriptor(tag);
	if (! newDesc) {
		*desc = NULL;
		*desc_size = sizeHeader;
		if ( (tag >= GF_ODF_ISO_RES_BEGIN_TAG) &&
		        (tag <= GF_ODF_ISO_RES_END_TAG) ) {
			return GF_ODF_FORBIDDEN_DESCRIPTOR;
		}
		else if (!tag || (tag == 0xFF)) {
			return GF_ODF_INVALID_DESCRIPTOR;
		}
#ifndef GPAC_MINIMAL_ODF
		return GF_OUT_OF_MEM;
#else
		gf_bs_skip_bytes(bs, size);
		*desc_size = size + sizeHeader - gf_odf_size_field_size(*desc_size);
		return GF_OK;
#endif
	}

	newDesc->tag = tag;
	err = gf_odf_read_descriptor(bs, newDesc, *desc_size);

	/*FFMPEG fix*/
	if ((tag==GF_ODF_SLC_TAG) && (((GF_SLConfig*)newDesc)->predefined==2)) {
		if (*desc_size==3) {
			*desc_size = 1;
			err = GF_OK;
		}
	}

	//little trick to handle lazy bitstreams that encode
	//SizeOfInstance on a fix number of bytes
	//This nb of bytes is added in Read methods
	*desc_size += sizeHeader - gf_odf_size_field_size(*desc_size);
	*desc = newDesc;
	if (err) {
		GF_LOG(GF_LOG_ERROR, GF_LOG_CODEC, ("[ODF] Error reading descriptor (tag %d size %d): %s\n", tag, size, gf_error_to_string(err) ));
		gf_odf_delete_descriptor(newDesc);
		*desc = NULL;
	}
	return err;
}

fixed #1895


GF_VVCConfig *gf_odf_vvc_cfg_read(u8 *dsi, u32 dsi_size)
{
	GF_BitStream *bs = gf_bs_new(dsi, dsi_size, GF_BITSTREAM_READ);
	GF_VVCConfig *cfg = gf_odf_vvc_cfg_read_bs(bs);
	gf_bs_del(bs);
	return cfg;
}

fixed #1895


GF_VPConfig *gf_odf_vp_cfg_read(u8 *dsi, u32 dsi_size)
{
	GF_BitStream *bs = gf_bs_new(dsi, dsi_size, GF_BITSTREAM_READ);
	GF_VPConfig *cfg = gf_odf_vp_cfg_read_bs(bs, GF_FALSE);
	gf_bs_del(bs);
	return cfg;
}

fixed #1895


GF_Err gf_odf_ac3_config_parse(u8 *dsi, u32 dsi_len, Bool is_ec3, GF_AC3Config *cfg)
{
	GF_BitStream *bs;
	GF_Err e;
	if (!cfg || !dsi) return GF_BAD_PARAM;
	bs = gf_bs_new(dsi, dsi_len, GF_BITSTREAM_READ);
	e = gf_odf_ac3_config_parse_bs(bs, is_ec3, cfg);
	gf_bs_del(bs);
	return e;
}

fixed #1895


GF_Err gf_odf_del_text_cfg(GF_TextConfig *desc)
{
	ResetTextConfig(desc);
	gf_list_del(desc->sample_descriptions);
	gf_free(desc);
	return GF_OK;
}

fixed #1895


GF_AV1Config *gf_odf_av1_cfg_read_bs(GF_BitStream *bs)
{
	return gf_odf_av1_cfg_read_bs_size(bs, 0);

}

fixed #1895


GF_Err gf_odf_ac3_cfg_write_bs(GF_AC3Config *cfg, GF_BitStream *bs)
{
	if (!cfg || !bs) return GF_BAD_PARAM;

	if (cfg->is_ec3) {
		u32 i;
		gf_bs_write_int(bs, cfg->brcode, 13);
		gf_bs_write_int(bs, cfg->nb_streams - 1, 3);
		for (i=0; i<cfg->nb_streams; i++) {
			gf_bs_write_int(bs, cfg->streams[i].fscod, 2);
			gf_bs_write_int(bs, cfg->streams[i].bsid, 5);
			gf_bs_write_int(bs, cfg->streams[i].bsmod, 5);
			gf_bs_write_int(bs, cfg->streams[i].acmod, 3);
			gf_bs_write_int(bs, cfg->streams[i].lfon, 1);
			gf_bs_write_int(bs, 0, 3);
			gf_bs_write_int(bs, cfg->streams[i].nb_dep_sub, 4);
			if (cfg->streams[i].nb_dep_sub) {
				gf_bs_write_int(bs, cfg->streams[i].chan_loc, 9);
			} else {
				gf_bs_write_int(bs, 0, 1);
			}
		}
	} else {
		gf_bs_write_int(bs, cfg->streams[0].fscod, 2);
		gf_bs_write_int(bs, cfg->streams[0].bsid, 5);
		gf_bs_write_int(bs, cfg->streams[0].bsmod, 3);
		gf_bs_write_int(bs, cfg->streams[0].acmod, 3);
		gf_bs_write_int(bs, cfg->streams[0].lfon, 1);
		gf_bs_write_int(bs, cfg->brcode, 5);
		gf_bs_write_int(bs, 0, 5);
	}
	return GF_OK;
}

fixed #1895


GF_VPConfig *gf_odf_vp_cfg_new()
{
	GF_VPConfig *cfg;
	GF_SAFEALLOC(cfg, GF_VPConfig);
	if (!cfg) return NULL;
	cfg->codec_initdata_size = 0;
	cfg->codec_initdata = NULL;
	return cfg;
}

fixed #1895


GF_Err gf_odf_size_descriptor_list(GF_List *descList, u32 *outSize)
{
	GF_Err e;
	u32 tmpSize, count, i;
	if (! descList) return GF_OK;

	count = gf_list_count(descList);
	for ( i = 0; i < count; i++ ) {
		GF_Descriptor *tmp = (GF_Descriptor*)gf_list_get(descList, i);
		if (tmp) {
			e = gf_odf_size_descriptor(tmp, &tmpSize);
			if (e) return e;
			if (tmpSize) *outSize += tmpSize + gf_odf_size_field_size(tmpSize);
		}
	}
	return GF_OK;
}

fixed #1895


GF_AVCConfig *gf_odf_avc_cfg_read(u8 *dsi, u32 dsi_size)
{
	u32 i, count;
	GF_AVCConfig *avcc = gf_odf_avc_cfg_new();
	GF_BitStream *bs = gf_bs_new(dsi, dsi_size, GF_BITSTREAM_READ);
	avcc->configurationVersion = gf_bs_read_int(bs, 8);
	avcc->AVCProfileIndication  = gf_bs_read_int(bs, 8);
	avcc->profile_compatibility = gf_bs_read_int(bs, 8);
	avcc->AVCLevelIndication  = gf_bs_read_int(bs, 8);
	gf_bs_read_int(bs, 6);
	avcc->nal_unit_size = 1 + gf_bs_read_int(bs, 2);
	gf_bs_read_int(bs, 3);
	count = gf_bs_read_int(bs, 5);
	for (i=0; i<count; i++) {
		GF_NALUFFParam *sl = (GF_NALUFFParam *)gf_malloc(sizeof(GF_NALUFFParam));
		sl->size = gf_bs_read_int(bs, 16);
		sl->data = (char*)gf_malloc(sizeof(char)*sl->size);
		gf_bs_read_data(bs, sl->data, sl->size);
		gf_list_add(avcc->sequenceParameterSets, sl);
	}
	count = gf_bs_read_int(bs, 8);
	for (i=0; i<count; i++) {
		GF_NALUFFParam *sl = (GF_NALUFFParam *)gf_malloc(sizeof(GF_NALUFFParam));
		sl->size = gf_bs_read_int(bs, 16);
		sl->data = (char*)gf_malloc(sizeof(char)*sl->size);
		gf_bs_read_data(bs, sl->data, sl->size);
		gf_list_add(avcc->pictureParameterSets, sl);
	}
	if (gf_avc_is_rext_profile(avcc->AVCProfileIndication)) {
		gf_bs_read_int(bs, 6);
		avcc->chroma_format = gf_bs_read_int(bs, 2);
		gf_bs_read_int(bs, 5);
		avcc->luma_bit_depth = 8 + gf_bs_read_int(bs, 3);
		gf_bs_read_int(bs, 5);
		avcc->chroma_bit_depth = 8 + gf_bs_read_int(bs, 3);

		count = gf_bs_read_int(bs, 8);
		if (count) {
			avcc->sequenceParameterSetExtensions = gf_list_new();
			for (i=0; i<count; i++) {
				GF_NALUFFParam *sl = (GF_NALUFFParam *)gf_malloc(sizeof(GF_NALUFFParam));
				sl->size = gf_bs_read_u16(bs);
				sl->data = (char *)gf_malloc(sizeof(char) * sl->size);
				gf_bs_read_data(bs, sl->data, sl->size);
				gf_list_add(avcc->sequenceParameterSetExtensions, sl);
			}
		}
	}

	gf_bs_del(bs);
	return avcc;
}

fixed #1895


void ResetTextConfig(GF_TextConfig *desc)
{
	GF_List *bck;
	while (gf_list_count(desc->sample_descriptions)) {
		GF_TextSampleDescriptor *sd = (GF_TextSampleDescriptor *)gf_list_get(desc->sample_descriptions, 0);
		gf_list_rem(desc->sample_descriptions, 0);
		gf_odf_del_tx3g(sd);
	}
	bck = desc->sample_descriptions;
	memset(desc, 0, sizeof(GF_TextConfig));
	desc->tag = GF_ODF_TEXT_CFG_TAG;
	desc->sample_descriptions = bck;
}

fixed #1895