1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // UNSUPPORTED: c++03, c++11, c++14
10 // <numeric>
11
12 // template<class _M, class _N>
13 // constexpr common_type_t<_M,_N> lcm(_M __m, _N __n)
14
15 #include <numeric>
16 #include <cassert>
17 #include <climits>
18 #include <cstdint>
19 #include <limits>
20 #include <type_traits>
21 #include "test_macros.h"
22
23 constexpr struct {
24 int x;
25 int y;
26 int expect;
27 } Cases[] = {
28 {0, 0, 0},
29 {1, 0, 0},
30 {0, 1, 0},
31 {1, 1, 1},
32 {2, 3, 6},
33 {2, 4, 4},
34 {3, 17, 51},
35 {36, 18, 36}
36 };
37
38 template <typename Input1, typename Input2, typename Output>
test0(int in1,int in2,int out)39 constexpr bool test0(int in1, int in2, int out)
40 {
41 auto value1 = static_cast<Input1>(in1);
42 auto value2 = static_cast<Input2>(in2);
43 static_assert(std::is_same_v<Output, decltype(std::lcm(value1, value2))>, "");
44 static_assert(std::is_same_v<Output, decltype(std::lcm(value2, value1))>, "");
45 assert(static_cast<Output>(out) == std::lcm(value1, value2));
46 return true;
47 }
48
49
50 template <typename Input1, typename Input2 = Input1>
do_test(int=0)51 constexpr bool do_test(int = 0)
52 {
53 using S1 = std::make_signed_t<Input1>;
54 using S2 = std::make_signed_t<Input2>;
55 using U1 = std::make_unsigned_t<Input1>;
56 using U2 = std::make_unsigned_t<Input2>;
57 bool accumulate = true;
58 for (auto TC : Cases) {
59 { // Test with two signed types
60 using Output = std::common_type_t<S1, S2>;
61 accumulate &= test0<S1, S2, Output>(TC.x, TC.y, TC.expect);
62 accumulate &= test0<S1, S2, Output>(-TC.x, TC.y, TC.expect);
63 accumulate &= test0<S1, S2, Output>(TC.x, -TC.y, TC.expect);
64 accumulate &= test0<S1, S2, Output>(-TC.x, -TC.y, TC.expect);
65 accumulate &= test0<S2, S1, Output>(TC.x, TC.y, TC.expect);
66 accumulate &= test0<S2, S1, Output>(-TC.x, TC.y, TC.expect);
67 accumulate &= test0<S2, S1, Output>(TC.x, -TC.y, TC.expect);
68 accumulate &= test0<S2, S1, Output>(-TC.x, -TC.y, TC.expect);
69 }
70 { // test with two unsigned types
71 using Output = std::common_type_t<U1, U2>;
72 accumulate &= test0<U1, U2, Output>(TC.x, TC.y, TC.expect);
73 accumulate &= test0<U2, U1, Output>(TC.x, TC.y, TC.expect);
74 }
75 { // Test with mixed signs
76 using Output = std::common_type_t<S1, U2>;
77 accumulate &= test0<S1, U2, Output>(TC.x, TC.y, TC.expect);
78 accumulate &= test0<U2, S1, Output>(TC.x, TC.y, TC.expect);
79 accumulate &= test0<S1, U2, Output>(-TC.x, TC.y, TC.expect);
80 accumulate &= test0<U2, S1, Output>(TC.x, -TC.y, TC.expect);
81 }
82 { // Test with mixed signs
83 using Output = std::common_type_t<S2, U1>;
84 accumulate &= test0<S2, U1, Output>(TC.x, TC.y, TC.expect);
85 accumulate &= test0<U1, S2, Output>(TC.x, TC.y, TC.expect);
86 accumulate &= test0<S2, U1, Output>(-TC.x, TC.y, TC.expect);
87 accumulate &= test0<U1, S2, Output>(TC.x, -TC.y, TC.expect);
88 }
89 }
90 return accumulate;
91 }
92
93 template <class T>
test_limits()94 constexpr bool test_limits() {
95 assert(std::lcm(std::numeric_limits<T>::max() - 1, std::numeric_limits<T>::max() - 1) == std::numeric_limits<T>::max() - 1);
96 assert(std::lcm(std::numeric_limits<T>::max(), std::numeric_limits<T>::max()) == std::numeric_limits<T>::max());
97 return true;
98 }
99
main(int argc,char **)100 int main(int argc, char**)
101 {
102 int non_cce = argc; // a value that can't possibly be constexpr
103
104 static_assert(do_test<signed char>(), "");
105 static_assert(do_test<short>(), "");
106 static_assert(do_test<int>(), "");
107 static_assert(do_test<long>(), "");
108 static_assert(do_test<long long>(), "");
109
110 assert(do_test<signed char>(non_cce));
111 assert(do_test<short>(non_cce));
112 assert(do_test<int>(non_cce));
113 assert(do_test<long>(non_cce));
114 assert(do_test<long long>(non_cce));
115
116 static_assert(do_test<std::int8_t>(), "");
117 static_assert(do_test<std::int16_t>(), "");
118 static_assert(do_test<std::int32_t>(), "");
119 static_assert(do_test<std::int64_t>(), "");
120
121 assert(do_test<std::int8_t>(non_cce));
122 assert(do_test<std::int16_t>(non_cce));
123 assert(do_test<std::int32_t>(non_cce));
124 assert(do_test<std::int64_t>(non_cce));
125
126 static_assert(do_test<signed char, int>(), "");
127 static_assert(do_test<int, signed char>(), "");
128 static_assert(do_test<short, int>(), "");
129 static_assert(do_test<int, short>(), "");
130 static_assert(do_test<int, long>(), "");
131 static_assert(do_test<long, int>(), "");
132 static_assert(do_test<int, long long>(), "");
133 static_assert(do_test<long long, int>(), "");
134
135 assert((do_test<signed char, int>(non_cce)));
136 assert((do_test<int, signed char>(non_cce)));
137 assert((do_test<short, int>(non_cce)));
138 assert((do_test<int, short>(non_cce)));
139 assert((do_test<int, long>(non_cce)));
140 assert((do_test<long, int>(non_cce)));
141 assert((do_test<int, long long>(non_cce)));
142 assert((do_test<long long, int>(non_cce)));
143
144 // LWG#2837
145 {
146 auto res1 = std::lcm(static_cast<std::int64_t>(1234), INT32_MIN);
147 TEST_IGNORE_NODISCARD std::lcm(INT_MIN, 2UL); // this used to trigger UBSAN
148 static_assert(std::is_same_v<decltype(res1), std::int64_t>, "");
149 assert(res1 == 1324997410816LL);
150 }
151
152 // https://github.com/llvm/llvm-project/issues/96196
153 {
154 assert(test_limits<unsigned int>());
155 assert(test_limits<std::uint32_t>());
156 assert(test_limits<std::uint64_t>());
157 assert(test_limits<int>());
158 assert(test_limits<std::int32_t>());
159 assert(test_limits<std::int64_t>());
160
161 static_assert(test_limits<unsigned int>(), "");
162 static_assert(test_limits<std::uint32_t>(), "");
163 static_assert(test_limits<std::uint64_t>(), "");
164 static_assert(test_limits<int>(), "");
165 static_assert(test_limits<std::int32_t>(), "");
166 static_assert(test_limits<std::int64_t>(), "");
167 }
168
169 return 0;
170 }
171