1 //===----------------------------------------------------------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is dual licensed under the MIT and the University of Illinois Open 6 // Source Licenses. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // UNSUPPORTED: c++98, c++03, c++11, c++14, c++17 10 11 // template <class T> 12 // constexpr int countr_zero(T x) noexcept; 13 14 // Returns: The number of consecutive 0 bits, starting from the most significant bit. 15 // [ Note: Returns N if x == 0. ] 16 // 17 // Remarks: This function shall not participate in overload resolution unless 18 // T is an unsigned integer type 19 20 #include <bit> 21 #include <cstdint> 22 #include <type_traits> 23 #include <cassert> 24 25 #include "test_macros.h" 26 27 class A{}; 28 enum E1 : unsigned char { rEd }; 29 enum class E2 : unsigned char { red }; 30 31 template <typename T> 32 constexpr bool constexpr_test() 33 { 34 const int dig = std::numeric_limits<T>::digits; 35 return std::countr_zero(T(0)) == dig 36 && std::countr_zero(T(1)) == 0 37 && std::countr_zero(T(2)) == 1 38 && std::countr_zero(T(3)) == 0 39 && std::countr_zero(T(4)) == 2 40 && std::countr_zero(T(5)) == 0 41 && std::countr_zero(T(6)) == 1 42 && std::countr_zero(T(7)) == 0 43 && std::countr_zero(T(8)) == 3 44 && std::countr_zero(T(9)) == 0 45 && std::countr_zero(std::numeric_limits<T>::max()) == 0 46 ; 47 } 48 49 50 template <typename T> 51 void runtime_test() 52 { 53 ASSERT_SAME_TYPE(int, decltype(std::countr_zero(T(0)))); 54 ASSERT_NOEXCEPT( std::countr_zero(T(0))); 55 56 assert( std::countr_zero(T(121)) == 0); 57 assert( std::countr_zero(T(122)) == 1); 58 assert( std::countr_zero(T(123)) == 0); 59 assert( std::countr_zero(T(124)) == 2); 60 assert( std::countr_zero(T(125)) == 0); 61 assert( std::countr_zero(T(126)) == 1); 62 assert( std::countr_zero(T(127)) == 0); 63 assert( std::countr_zero(T(128)) == 7); 64 assert( std::countr_zero(T(129)) == 0); 65 assert( std::countr_zero(T(130)) == 1); 66 } 67 68 int main() 69 { 70 71 { 72 auto lambda = [](auto x) -> decltype(std::countr_zero(x)) {}; 73 using L = decltype(lambda); 74 75 static_assert( std::is_invocable_v<L, unsigned char>, ""); 76 static_assert( std::is_invocable_v<L, unsigned int>, ""); 77 static_assert( std::is_invocable_v<L, unsigned long>, ""); 78 static_assert( std::is_invocable_v<L, unsigned long long>, ""); 79 80 static_assert( std::is_invocable_v<L, uint8_t>, ""); 81 static_assert( std::is_invocable_v<L, uint16_t>, ""); 82 static_assert( std::is_invocable_v<L, uint32_t>, ""); 83 static_assert( std::is_invocable_v<L, uint64_t>, ""); 84 static_assert( std::is_invocable_v<L, size_t>, ""); 85 86 static_assert( std::is_invocable_v<L, uintmax_t>, ""); 87 static_assert( std::is_invocable_v<L, uintptr_t>, ""); 88 89 90 static_assert(!std::is_invocable_v<L, int>, ""); 91 static_assert(!std::is_invocable_v<L, signed int>, ""); 92 static_assert(!std::is_invocable_v<L, long>, ""); 93 static_assert(!std::is_invocable_v<L, long long>, ""); 94 95 static_assert(!std::is_invocable_v<L, int8_t>, ""); 96 static_assert(!std::is_invocable_v<L, int16_t>, ""); 97 static_assert(!std::is_invocable_v<L, int32_t>, ""); 98 static_assert(!std::is_invocable_v<L, int64_t>, ""); 99 static_assert(!std::is_invocable_v<L, ptrdiff_t>, ""); 100 101 static_assert(!std::is_invocable_v<L, bool>, ""); 102 static_assert(!std::is_invocable_v<L, signed char>, ""); 103 static_assert(!std::is_invocable_v<L, char16_t>, ""); 104 static_assert(!std::is_invocable_v<L, char32_t>, ""); 105 106 #ifndef _LIBCPP_HAS_NO_INT128 107 static_assert( std::is_invocable_v<L, __uint128_t>, ""); 108 static_assert(!std::is_invocable_v<L, __int128_t>, ""); 109 #endif 110 111 static_assert(!std::is_invocable_v<L, A>, ""); 112 static_assert(!std::is_invocable_v<L, E1>, ""); 113 static_assert(!std::is_invocable_v<L, E2>, ""); 114 } 115 116 static_assert(constexpr_test<unsigned char>(), ""); 117 static_assert(constexpr_test<unsigned short>(), ""); 118 static_assert(constexpr_test<unsigned>(), ""); 119 static_assert(constexpr_test<unsigned long>(), ""); 120 static_assert(constexpr_test<unsigned long long>(), ""); 121 122 static_assert(constexpr_test<uint8_t>(), ""); 123 static_assert(constexpr_test<uint16_t>(), ""); 124 static_assert(constexpr_test<uint32_t>(), ""); 125 static_assert(constexpr_test<uint64_t>(), ""); 126 static_assert(constexpr_test<size_t>(), ""); 127 static_assert(constexpr_test<uintmax_t>(), ""); 128 static_assert(constexpr_test<uintptr_t>(), ""); 129 130 #ifndef _LIBCPP_HAS_NO_INT128 131 static_assert(constexpr_test<__uint128_t>(), ""); 132 #endif 133 134 runtime_test<unsigned char>(); 135 runtime_test<unsigned>(); 136 runtime_test<unsigned short>(); 137 runtime_test<unsigned long>(); 138 runtime_test<unsigned long long>(); 139 140 runtime_test<uint8_t>(); 141 runtime_test<uint16_t>(); 142 runtime_test<uint32_t>(); 143 runtime_test<uint64_t>(); 144 runtime_test<size_t>(); 145 runtime_test<uintmax_t>(); 146 runtime_test<uintptr_t>(); 147 148 #ifndef _LIBCPP_HAS_NO_INT128 149 runtime_test<__uint128_t>(); 150 151 { 152 __uint128_t val = 128; 153 154 val <<= 32; 155 assert( std::countr_zero(val-1) == 0); 156 assert( std::countr_zero(val) == 39); 157 assert( std::countr_zero(val+1) == 0); 158 val <<= 2; 159 assert( std::countr_zero(val-1) == 0); 160 assert( std::countr_zero(val) == 41); 161 assert( std::countr_zero(val+1) == 0); 162 val <<= 3; 163 assert( std::countr_zero(val-1) == 0); 164 assert( std::countr_zero(val) == 44); 165 assert( std::countr_zero(val+1) == 0); 166 } 167 #endif 168 169 } 170