Method IsConstantVisitor

tensorflow/compiler/xla/client/xla_builder.cc:206–257

}

void XlaBuilder::IsConstantVisitor(const int64 op_handle,
                                   absl::flat_hash_set<int64>* visited,
                                   bool* is_constant) const {
  if (visited->contains(op_handle) || !*is_constant) {
    return;
  }

  const HloInstructionProto& instr =
      *(LookUpInstructionByHandle(op_handle).ValueOrDie());
  const HloOpcode opcode = StringToHloOpcode(instr.opcode()).ValueOrDie();
  switch (opcode) {
    default:
      for (const int64 operand_id : instr.operand_ids()) {
        IsConstantVisitor(operand_id, visited, is_constant);
      }
      // TODO(b/32495713): We aren't checking the called computations.
      break;

    case HloOpcode::kGetDimensionSize:
      // GetDimensionSize is always considered constant in XLA -- If a dynamic
      // dimension is presented, -1 is returned.
      break;

    // Non functional ops.
    case HloOpcode::kRng:
    case HloOpcode::kAllReduce:
      // TODO(b/33009255): Implement constant folding for cross replica sum.
    case HloOpcode::kInfeed:
    case HloOpcode::kOutfeed:
    case HloOpcode::kCall:
      // TODO(b/32495713): We aren't checking the to_apply computation itself,
      // so we conservatively say that computations containing the Call op
      // cannot be constant.  We cannot set is_functional=false in other similar
      // cases since we're already relying on IsConstant to return true.
    case HloOpcode::kCustomCall:
    case HloOpcode::kWhile:
      // TODO(b/32495713): We aren't checking the condition and body
      // computations themselves.
    case HloOpcode::kScatter:
      // TODO(b/32495713): We aren't checking the embedded computation in
      // Scatter.
    case HloOpcode::kSend:
    case HloOpcode::kRecv:
    case HloOpcode::kParameter:
      *is_constant = false;
      break;
  }
  if (!*is_constant) {
    VLOG(1) << "Non-constant: " << instr.name();
  }
  visited->insert(op_handle);
}

Status XlaBuilder::SetDynamicBinding(int64 dynamic_size_param_num,
                                     ShapeIndex dynamic_size_param_index,