1/* Copyright 2015 The TensorFlow Authors. All Rights Reserved.
2
3Licensed under the Apache License, Version 2.0 (the "License");
4you may not use this file except in compliance with the License.
5You may obtain a copy of the License at
6
7    http://www.apache.org/licenses/LICENSE-2.0
8
9Unless required by applicable law or agreed to in writing, software
10distributed under the License is distributed on an "AS IS" BASIS,
11WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12See the License for the specific language governing permissions and
13limitations under the License.
14==============================================================================*/
15
16#include "tensorflow/core/util/overflow.h"
17#include <cmath>
18#include "tensorflow/core/platform/macros.h"
19#include "tensorflow/core/platform/test.h"
20
21namespace tensorflow {
22namespace {
23
24TEST(OverflowTest, Nonnegative) {
25  // Various interesting values
26  std::vector<int64> interesting = {0, std::numeric_limits<int64>::max()};
27  for (int i = 0; i < 63; i++) {
28    int64 bit = static_cast<int64>(1) << i;
29    interesting.push_back(bit);
30    interesting.push_back(bit + 1);
31    interesting.push_back(bit - 1);
32  }
33  for (const int64 mid : {static_cast<int64>(1) << 32,
34                          static_cast<int64>(std::pow(2, 63.0 / 2))}) {
35    for (int i = -5; i < 5; i++) {
36      interesting.push_back(mid + i);
37    }
38  }
39
40  // Check all pairs
41  for (auto x : interesting) {
42    for (auto y : interesting) {
43      int64 xy = MultiplyWithoutOverflow(x, y);
44      long double dxy = static_cast<long double>(x) * y;
45      if (dxy > std::numeric_limits<int64>::max()) {
46        EXPECT_LT(xy, 0);
47      } else {
48        EXPECT_EQ(dxy, xy);
49      }
50    }
51  }
52}
53
54TEST(OverflowTest, Negative) {
55  const int64 negatives[] = {-1, std::numeric_limits<int64>::min()};
56  for (const int64 n : negatives) {
57    EXPECT_DEATH(MultiplyWithoutOverflow(n, 0), "");
58    EXPECT_DEATH(MultiplyWithoutOverflow(0, n), "");
59    EXPECT_DEATH(MultiplyWithoutOverflow(n, n), "");
60  }
61}
62
63}  // namespace
64}  // namespace tensorflow
65