1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "safe_math.h"
18
19#include <limits>
20
21#include "gtest/gtest.h"
22
23namespace art {
24namespace interpreter {
25
26TEST(SafeMath, Add) {
27  // Adding 1 overflows 0x7ff... to 0x800... aka max and min.
28  EXPECT_EQ(SafeAdd(std::numeric_limits<int32_t>::max(), 1),
29            std::numeric_limits<int32_t>::min());
30  EXPECT_EQ(SafeAdd(std::numeric_limits<int64_t>::max(), 1),
31            std::numeric_limits<int64_t>::min());
32
33  // Vanilla arithmetic should work too.
34  EXPECT_EQ(SafeAdd(std::numeric_limits<int32_t>::max() - 1, 1),
35            std::numeric_limits<int32_t>::max());
36  EXPECT_EQ(SafeAdd(std::numeric_limits<int64_t>::max() - 1, 1),
37            std::numeric_limits<int64_t>::max());
38
39  EXPECT_EQ(SafeAdd(std::numeric_limits<int32_t>::min() + 1, -1),
40            std::numeric_limits<int32_t>::min());
41  EXPECT_EQ(SafeAdd(std::numeric_limits<int64_t>::min() + 1, -1),
42            std::numeric_limits<int64_t>::min());
43
44  EXPECT_EQ(SafeAdd(int32_t(-1), -1), -2);
45  EXPECT_EQ(SafeAdd(int64_t(-1), -1), -2);
46
47  EXPECT_EQ(SafeAdd(int32_t(1), 1), 2);
48  EXPECT_EQ(SafeAdd(int64_t(1), 1), 2);
49
50  EXPECT_EQ(SafeAdd(int32_t(-1), 1), 0);
51  EXPECT_EQ(SafeAdd(int64_t(-1), 1), 0);
52
53  EXPECT_EQ(SafeAdd(int32_t(1), -1), 0);
54  EXPECT_EQ(SafeAdd(int64_t(1), -1), 0);
55
56  // Test sign extension of smaller operand sizes.
57  EXPECT_EQ(SafeAdd(int32_t(1), int8_t(-1)), 0);
58  EXPECT_EQ(SafeAdd(int64_t(1), int8_t(-1)), 0);
59}
60
61TEST(SafeMath, Sub) {
62  // Subtracting 1 underflows 0x800... to 0x7ff... aka min and max.
63  EXPECT_EQ(SafeSub(std::numeric_limits<int32_t>::min(), 1),
64            std::numeric_limits<int32_t>::max());
65  EXPECT_EQ(SafeSub(std::numeric_limits<int64_t>::min(), 1),
66            std::numeric_limits<int64_t>::max());
67
68  // Vanilla arithmetic should work too.
69  EXPECT_EQ(SafeSub(std::numeric_limits<int32_t>::max() - 1, -1),
70            std::numeric_limits<int32_t>::max());
71  EXPECT_EQ(SafeSub(std::numeric_limits<int64_t>::max() - 1, -1),
72            std::numeric_limits<int64_t>::max());
73
74  EXPECT_EQ(SafeSub(std::numeric_limits<int32_t>::min() + 1, 1),
75            std::numeric_limits<int32_t>::min());
76  EXPECT_EQ(SafeSub(std::numeric_limits<int64_t>::min() + 1, 1),
77            std::numeric_limits<int64_t>::min());
78
79  EXPECT_EQ(SafeSub(int32_t(-1), -1), 0);
80  EXPECT_EQ(SafeSub(int64_t(-1), -1), 0);
81
82  EXPECT_EQ(SafeSub(int32_t(1), 1), 0);
83  EXPECT_EQ(SafeSub(int64_t(1), 1), 0);
84
85  EXPECT_EQ(SafeSub(int32_t(-1), 1), -2);
86  EXPECT_EQ(SafeSub(int64_t(-1), 1), -2);
87
88  EXPECT_EQ(SafeSub(int32_t(1), -1), 2);
89  EXPECT_EQ(SafeSub(int64_t(1), -1), 2);
90
91  // Test sign extension of smaller operand sizes.
92  EXPECT_EQ(SafeAdd(int32_t(1), int8_t(-1)), 0);
93  EXPECT_EQ(SafeAdd(int64_t(1), int8_t(-1)), 0);
94}
95
96TEST(SafeMath, Mul) {
97  // Multiplying by 2 overflows 0x7ff...f to 0xfff...e aka max and -2.
98  EXPECT_EQ(SafeMul(std::numeric_limits<int32_t>::max(), 2),
99            -2);
100  EXPECT_EQ(SafeMul(std::numeric_limits<int64_t>::max(), 2),
101            -2);
102
103  // Vanilla arithmetic should work too.
104  EXPECT_EQ(SafeMul(std::numeric_limits<int32_t>::max() / 2, 2),
105            std::numeric_limits<int32_t>::max() - 1);  // -1 as LSB is lost by division.
106  EXPECT_EQ(SafeMul(std::numeric_limits<int64_t>::max() / 2, 2),
107            std::numeric_limits<int64_t>::max() - 1);  // -1 as LSB is lost by division.
108
109  EXPECT_EQ(SafeMul(std::numeric_limits<int32_t>::min() / 2, 2),
110            std::numeric_limits<int32_t>::min());
111  EXPECT_EQ(SafeMul(std::numeric_limits<int64_t>::min() / 2, 2),
112            std::numeric_limits<int64_t>::min());
113
114  EXPECT_EQ(SafeMul(int32_t(-1), -1), 1);
115  EXPECT_EQ(SafeMul(int64_t(-1), -1), 1);
116
117  EXPECT_EQ(SafeMul(int32_t(1), 1), 1);
118  EXPECT_EQ(SafeMul(int64_t(1), 1), 1);
119
120  EXPECT_EQ(SafeMul(int32_t(-1), 1), -1);
121  EXPECT_EQ(SafeMul(int64_t(-1), 1), -1);
122
123  EXPECT_EQ(SafeMul(int32_t(1), -1), -1);
124  EXPECT_EQ(SafeMul(int64_t(1), -1), -1);
125
126  // Test sign extension of smaller operand sizes.
127  EXPECT_EQ(SafeMul(int32_t(1), int8_t(-1)), -1);
128  EXPECT_EQ(SafeMul(int64_t(1), int8_t(-1)), -1);
129}
130
131}  // namespace interpreter
132}  // namespace art
133