text: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  
  /*!
   *  Copyright (c) 2019 by Contributors
   * \file int_op_overflow.h
   * \brief Utility functions to detect if an integer op will overflow.
   */
  #ifndef TVM_ARITHMETIC_INT_OP_OVERFLOW_H_
  #define TVM_ARITHMETIC_INT_OP_OVERFLOW_H_
  
  #include <limits>
  
  namespace tvm {
  namespace arith {
  
  /*!
   * \brief Check if an integer op with operand x, y will overflow.
   * \param x The left operand.
   * \param y The left operand.
   * \param min_value The minimum value of the domain.
   * \param max_value The maximum value of the domain.
   * \return Whether overflow can happen.
   * \tparam Op The integer operator.
   */
  template<typename Op>
  inline bool WillOverflow(int64_t x,
                           int64_t y,
                           int64_t min_value,
                           int64_t max_value) {
    return false;
  }
  
  template<>
  bool WillOverflow<ir::Add>(int64_t x,
                             int64_t y,
                             int64_t min_value,
                             int64_t max_value) {
    if ((y > 0) && (x > max_value - y)) return true;
    if ((y < 0) && (x < min_value - y)) return true;
    return false;
  }
  
  template<>
  bool WillOverflow<ir::Sub>(int64_t x,
                             int64_t y,
                             int64_t min_value,
                             int64_t max_value) {
    if ((y > 0) && (x < min_value + y)) return true;
    if ((y < 0) && (x > max_value + y)) return true;
    return false;
  }
  
  template<>
  bool WillOverflow<ir::Mul>(int64_t x,
                             int64_t y,
                             int64_t min_value,
                             int64_t max_value) {
    if (y == 0) return false;
    if (y > 0) {
      if (x < min_value / y)  return true;
      if (x > max_value / y)  return true;
    } else {
      if (y == -1 && x == std::numeric_limits<int64_t>::min()) return true;
      if (x > min_value / y)  return true;
      if (x < max_value / y)  return true;
    }
    return false;
  }
  
  template<>
  bool WillOverflow<ir::Mod>(int64_t x,
                             int64_t y,
                             int64_t min_value,
                             int64_t max_value) {
    return y == 0;
  }
  
  }  // namespace arith
  }  // namespace tvm
  #endif  // TVM_ARITHMETIC_INT_OP_OVERFLOW_H_
  