171 lines · cpp
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-exception6//7//===----------------------------------------------------------------------===//8//9// UNSUPPORTED: c++03, c++11, c++1410// <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 23constexpr 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 38template <typename Input1, typename Input2, typename Output>39constexpr 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 50template <typename Input1, typename Input2 = Input1>51constexpr 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 types60 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 types71 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 signs76 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 signs83 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 93template <class T>94constexpr 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 100int main(int argc, char**)101{102 int non_cce = argc; // a value that can't possibly be constexpr103 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#2837145 {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 UBSAN148 static_assert(std::is_same_v<decltype(res1), std::int64_t>, "");149 assert(res1 == 1324997410816LL);150 }151 152 // https://llvm.org/PR96196153 {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