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++03, c++11, c++14, c++17 10 11 // template <class T> 12 // constexpr int countl_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::countl_zero(T(0)) == dig 36 && std::countl_zero(T(1)) == dig - 1 37 && std::countl_zero(T(2)) == dig - 2 38 && std::countl_zero(T(3)) == dig - 2 39 && std::countl_zero(T(4)) == dig - 3 40 && std::countl_zero(T(5)) == dig - 3 41 && std::countl_zero(T(6)) == dig - 3 42 && std::countl_zero(T(7)) == dig - 3 43 && std::countl_zero(T(8)) == dig - 4 44 && std::countl_zero(T(9)) == dig - 4 45 && std::countl_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::countl_zero(T(0)))); 54 ASSERT_NOEXCEPT( std::countl_zero(T(0))); 55 const int dig = std::numeric_limits<T>::digits; 56 57 assert( std::countl_zero(T(121)) == dig - 7); 58 assert( std::countl_zero(T(122)) == dig - 7); 59 assert( std::countl_zero(T(123)) == dig - 7); 60 assert( std::countl_zero(T(124)) == dig - 7); 61 assert( std::countl_zero(T(125)) == dig - 7); 62 assert( std::countl_zero(T(126)) == dig - 7); 63 assert( std::countl_zero(T(127)) == dig - 7); 64 assert( std::countl_zero(T(128)) == dig - 8); 65 assert( std::countl_zero(T(129)) == dig - 8); 66 assert( std::countl_zero(T(130)) == dig - 8); 67 } 68 69 int main() 70 { 71 72 { 73 auto lambda = [](auto x) -> decltype(std::countl_zero(x)) {}; 74 using L = decltype(lambda); 75 76 static_assert( std::is_invocable_v<L, unsigned char>, ""); 77 static_assert( std::is_invocable_v<L, unsigned int>, ""); 78 static_assert( std::is_invocable_v<L, unsigned long>, ""); 79 static_assert( std::is_invocable_v<L, unsigned long long>, ""); 80 81 static_assert( std::is_invocable_v<L, uint8_t>, ""); 82 static_assert( std::is_invocable_v<L, uint16_t>, ""); 83 static_assert( std::is_invocable_v<L, uint32_t>, ""); 84 static_assert( std::is_invocable_v<L, uint64_t>, ""); 85 static_assert( std::is_invocable_v<L, size_t>, ""); 86 87 static_assert( std::is_invocable_v<L, uintmax_t>, ""); 88 static_assert( std::is_invocable_v<L, uintptr_t>, ""); 89 90 91 static_assert(!std::is_invocable_v<L, int>, ""); 92 static_assert(!std::is_invocable_v<L, signed int>, ""); 93 static_assert(!std::is_invocable_v<L, long>, ""); 94 static_assert(!std::is_invocable_v<L, long long>, ""); 95 96 static_assert(!std::is_invocable_v<L, int8_t>, ""); 97 static_assert(!std::is_invocable_v<L, int16_t>, ""); 98 static_assert(!std::is_invocable_v<L, int32_t>, ""); 99 static_assert(!std::is_invocable_v<L, int64_t>, ""); 100 static_assert(!std::is_invocable_v<L, ptrdiff_t>, ""); 101 102 static_assert(!std::is_invocable_v<L, bool>, ""); 103 static_assert(!std::is_invocable_v<L, signed char>, ""); 104 static_assert(!std::is_invocable_v<L, char16_t>, ""); 105 static_assert(!std::is_invocable_v<L, char32_t>, ""); 106 107 #ifndef _LIBCPP_HAS_NO_INT128 108 static_assert( std::is_invocable_v<L, __uint128_t>, ""); 109 static_assert(!std::is_invocable_v<L, __int128_t>, ""); 110 #endif 111 112 static_assert(!std::is_invocable_v<L, A>, ""); 113 static_assert(!std::is_invocable_v<L, E1>, ""); 114 static_assert(!std::is_invocable_v<L, E2>, ""); 115 } 116 117 static_assert(constexpr_test<unsigned char>(), ""); 118 static_assert(constexpr_test<unsigned short>(), ""); 119 static_assert(constexpr_test<unsigned>(), ""); 120 static_assert(constexpr_test<unsigned long>(), ""); 121 static_assert(constexpr_test<unsigned long long>(), ""); 122 123 static_assert(constexpr_test<uint8_t>(), ""); 124 static_assert(constexpr_test<uint16_t>(), ""); 125 static_assert(constexpr_test<uint32_t>(), ""); 126 static_assert(constexpr_test<uint64_t>(), ""); 127 static_assert(constexpr_test<size_t>(), ""); 128 static_assert(constexpr_test<uintmax_t>(), ""); 129 static_assert(constexpr_test<uintptr_t>(), ""); 130 131 #ifndef _LIBCPP_HAS_NO_INT128 132 static_assert(constexpr_test<__uint128_t>(), ""); 133 #endif 134 135 136 runtime_test<unsigned char>(); 137 runtime_test<unsigned>(); 138 runtime_test<unsigned short>(); 139 runtime_test<unsigned long>(); 140 runtime_test<unsigned long long>(); 141 142 runtime_test<uint8_t>(); 143 runtime_test<uint16_t>(); 144 runtime_test<uint32_t>(); 145 runtime_test<uint64_t>(); 146 runtime_test<size_t>(); 147 runtime_test<uintmax_t>(); 148 runtime_test<uintptr_t>(); 149 150 #ifndef _LIBCPP_HAS_NO_INT128 151 runtime_test<__uint128_t>(); 152 153 { 154 const int dig = std::numeric_limits<__uint128_t>::digits; 155 __uint128_t val = 128; 156 157 val <<= 32; 158 assert( std::countl_zero(val-1) == dig - 39); 159 assert( std::countl_zero(val) == dig - 40); 160 assert( std::countl_zero(val+1) == dig - 40); 161 val <<= 2; 162 assert( std::countl_zero(val-1) == dig - 41); 163 assert( std::countl_zero(val) == dig - 42); 164 assert( std::countl_zero(val+1) == dig - 42); 165 val <<= 3; 166 assert( std::countl_zero(val-1) == dig - 44); 167 assert( std::countl_zero(val) == dig - 45); 168 assert( std::countl_zero(val+1) == dig - 45); 169 } 170 #endif 171 172 } 173