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, c++17 10 11 // template <class T> 12 // constexpr int bit_width(T x) noexcept; 13 14 // Constraints: T is an unsigned integer type 15 // Returns: If x == 0, 0; otherwise one plus the base-2 logarithm of x, with any fractional part discarded. 16 17 18 #include <bit> 19 #include <cassert> 20 #include <cstddef> 21 #include <cstdint> 22 #include <limits> 23 #include <type_traits> 24 25 #include "test_macros.h" 26 27 struct A {}; 28 enum E1 : unsigned char { rEd }; 29 enum class E2 : unsigned char { red }; 30 31 template <class T> 32 constexpr bool test() 33 { 34 ASSERT_SAME_TYPE(decltype(std::bit_width(T())), int); 35 ASSERT_NOEXCEPT(std::bit_width(T())); 36 T max = std::numeric_limits<T>::max(); 37 38 assert(std::bit_width(T(0)) == 0); 39 assert(std::bit_width(T(1)) == 1); 40 assert(std::bit_width(T(2)) == 2); 41 assert(std::bit_width(T(3)) == 2); 42 assert(std::bit_width(T(4)) == 3); 43 assert(std::bit_width(T(5)) == 3); 44 assert(std::bit_width(T(6)) == 3); 45 assert(std::bit_width(T(7)) == 3); 46 assert(std::bit_width(T(8)) == 4); 47 assert(std::bit_width(T(9)) == 4); 48 assert(std::bit_width(T(125)) == 7); 49 assert(std::bit_width(T(126)) == 7); 50 assert(std::bit_width(T(127)) == 7); 51 assert(std::bit_width(T(128)) == 8); 52 assert(std::bit_width(T(129)) == 8); 53 assert(std::bit_width(T(130)) == 8); 54 assert(std::bit_width(T(max - 1)) == std::numeric_limits<T>::digits); 55 assert(std::bit_width(max) == std::numeric_limits<T>::digits); 56 57 #ifndef TEST_HAS_NO_INT128 58 if constexpr (std::is_same_v<T, __uint128_t>) { 59 T val = 128; 60 val <<= 32; 61 assert(std::bit_width(val-1) == 39); 62 assert(std::bit_width(val) == 40); 63 assert(std::bit_width(val+1) == 40); 64 val <<= 60; 65 assert(std::bit_width(val-1) == 99); 66 assert(std::bit_width(val) == 100); 67 assert(std::bit_width(val+1) == 100); 68 } 69 #endif 70 71 return true; 72 } 73 74 int main(int, char**) 75 { 76 77 { 78 auto lambda = [](auto x) -> decltype(std::bit_width(x)) {}; 79 using L = decltype(lambda); 80 81 static_assert(!std::is_invocable_v<L, signed char>); 82 static_assert(!std::is_invocable_v<L, short>); 83 static_assert(!std::is_invocable_v<L, int>); 84 static_assert(!std::is_invocable_v<L, long>); 85 static_assert(!std::is_invocable_v<L, long long>); 86 #ifndef TEST_HAS_NO_INT128 87 static_assert(!std::is_invocable_v<L, __int128_t>); 88 #endif 89 90 static_assert(!std::is_invocable_v<L, std::int8_t>); 91 static_assert(!std::is_invocable_v<L, std::int16_t>); 92 static_assert(!std::is_invocable_v<L, std::int32_t>); 93 static_assert(!std::is_invocable_v<L, std::int64_t>); 94 static_assert(!std::is_invocable_v<L, std::intmax_t>); 95 static_assert(!std::is_invocable_v<L, std::intptr_t>); 96 static_assert(!std::is_invocable_v<L, std::ptrdiff_t>); 97 98 static_assert(!std::is_invocable_v<L, bool>); 99 static_assert(!std::is_invocable_v<L, char>); 100 static_assert(!std::is_invocable_v<L, wchar_t>); 101 #ifndef TEST_HAS_NO_CHAR8_T 102 static_assert(!std::is_invocable_v<L, char8_t>); 103 #endif 104 static_assert(!std::is_invocable_v<L, char16_t>); 105 static_assert(!std::is_invocable_v<L, char32_t>); 106 107 static_assert(!std::is_invocable_v<L, A>); 108 static_assert(!std::is_invocable_v<L, A*>); 109 static_assert(!std::is_invocable_v<L, E1>); 110 static_assert(!std::is_invocable_v<L, E2>); 111 } 112 113 static_assert(test<unsigned char>()); 114 static_assert(test<unsigned short>()); 115 static_assert(test<unsigned int>()); 116 static_assert(test<unsigned long>()); 117 static_assert(test<unsigned long long>()); 118 #ifndef TEST_HAS_NO_INT128 119 static_assert(test<__uint128_t>()); 120 #endif 121 static_assert(test<std::uint8_t>()); 122 static_assert(test<std::uint16_t>()); 123 static_assert(test<std::uint32_t>()); 124 static_assert(test<std::uint64_t>()); 125 static_assert(test<std::uintmax_t>()); 126 static_assert(test<std::uintptr_t>()); 127 static_assert(test<std::size_t>()); 128 129 test<unsigned char>(); 130 test<unsigned short>(); 131 test<unsigned int>(); 132 test<unsigned long>(); 133 test<unsigned long long>(); 134 #ifndef TEST_HAS_NO_INT128 135 test<__uint128_t>(); 136 #endif 137 test<std::uint8_t>(); 138 test<std::uint16_t>(); 139 test<std::uint32_t>(); 140 test<std::uint64_t>(); 141 test<std::uintmax_t>(); 142 test<std::uintptr_t>(); 143 test<std::size_t>(); 144 145 return 0; 146 } 147