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 T 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 <cstdint> 21 #include <type_traits> 22 23 #include "test_macros.h" 24 25 struct A {}; 26 enum E1 : unsigned char { rEd }; 27 enum class E2 : unsigned char { red }; 28 29 template <class T> 30 constexpr bool test() 31 { 32 ASSERT_SAME_TYPE(decltype(std::bit_width(T())), T); 33 ASSERT_NOEXCEPT(std::bit_width(T())); 34 T max = std::numeric_limits<T>::max(); 35 36 assert(std::bit_width(T(0)) == T(0)); 37 assert(std::bit_width(T(1)) == T(1)); 38 assert(std::bit_width(T(2)) == T(2)); 39 assert(std::bit_width(T(3)) == T(2)); 40 assert(std::bit_width(T(4)) == T(3)); 41 assert(std::bit_width(T(5)) == T(3)); 42 assert(std::bit_width(T(6)) == T(3)); 43 assert(std::bit_width(T(7)) == T(3)); 44 assert(std::bit_width(T(8)) == T(4)); 45 assert(std::bit_width(T(9)) == T(4)); 46 assert(std::bit_width(T(125)) == T(7)); 47 assert(std::bit_width(T(126)) == T(7)); 48 assert(std::bit_width(T(127)) == T(7)); 49 assert(std::bit_width(T(128)) == T(8)); 50 assert(std::bit_width(T(129)) == T(8)); 51 assert(std::bit_width(T(130)) == T(8)); 52 assert(std::bit_width(T(max - 1)) == T(std::numeric_limits<T>::digits)); 53 assert(std::bit_width(max) == T(std::numeric_limits<T>::digits)); 54 55 #ifndef _LIBCPP_HAS_NO_INT128 56 if constexpr (std::is_same_v<T, __uint128_t>) { 57 T val = 128; 58 val <<= 32; 59 assert(std::bit_width(val-1) == 39); 60 assert(std::bit_width(val) == 40); 61 assert(std::bit_width(val+1) == 40); 62 val <<= 60; 63 assert(std::bit_width(val-1) == 99); 64 assert(std::bit_width(val) == 100); 65 assert(std::bit_width(val+1) == 100); 66 } 67 #endif 68 69 return true; 70 } 71 72 int main(int, char**) 73 { 74 75 { 76 auto lambda = [](auto x) -> decltype(std::bit_width(x)) {}; 77 using L = decltype(lambda); 78 79 static_assert(!std::is_invocable_v<L, signed char>); 80 static_assert(!std::is_invocable_v<L, short>); 81 static_assert(!std::is_invocable_v<L, int>); 82 static_assert(!std::is_invocable_v<L, long>); 83 static_assert(!std::is_invocable_v<L, long long>); 84 #ifndef _LIBCPP_HAS_NO_INT128 85 static_assert(!std::is_invocable_v<L, __int128_t>); 86 #endif 87 88 static_assert(!std::is_invocable_v<L, int8_t>); 89 static_assert(!std::is_invocable_v<L, int16_t>); 90 static_assert(!std::is_invocable_v<L, int32_t>); 91 static_assert(!std::is_invocable_v<L, int64_t>); 92 static_assert(!std::is_invocable_v<L, intmax_t>); 93 static_assert(!std::is_invocable_v<L, intptr_t>); 94 static_assert(!std::is_invocable_v<L, ptrdiff_t>); 95 96 static_assert(!std::is_invocable_v<L, bool>); 97 static_assert(!std::is_invocable_v<L, char>); 98 static_assert(!std::is_invocable_v<L, wchar_t>); 99 #ifndef _LIBCPP_HAS_NO_CHAR8_T 100 static_assert(!std::is_invocable_v<L, char8_t>); 101 #endif 102 static_assert(!std::is_invocable_v<L, char16_t>); 103 static_assert(!std::is_invocable_v<L, char32_t>); 104 105 static_assert(!std::is_invocable_v<L, A>); 106 static_assert(!std::is_invocable_v<L, A*>); 107 static_assert(!std::is_invocable_v<L, E1>); 108 static_assert(!std::is_invocable_v<L, E2>); 109 } 110 111 static_assert(test<unsigned char>()); 112 static_assert(test<unsigned short>()); 113 static_assert(test<unsigned int>()); 114 static_assert(test<unsigned long>()); 115 static_assert(test<unsigned long long>()); 116 #ifndef _LIBCPP_HAS_NO_INT128 117 static_assert(test<__uint128_t>()); 118 #endif 119 static_assert(test<uint8_t>()); 120 static_assert(test<uint16_t>()); 121 static_assert(test<uint32_t>()); 122 static_assert(test<uint64_t>()); 123 static_assert(test<uintmax_t>()); 124 static_assert(test<uintptr_t>()); 125 static_assert(test<size_t>()); 126 127 test<unsigned char>(); 128 test<unsigned short>(); 129 test<unsigned int>(); 130 test<unsigned long>(); 131 test<unsigned long long>(); 132 #ifndef _LIBCPP_HAS_NO_INT128 133 test<__uint128_t>(); 134 #endif 135 test<uint8_t>(); 136 test<uint16_t>(); 137 test<uint32_t>(); 138 test<uint64_t>(); 139 test<uintmax_t>(); 140 test<uintptr_t>(); 141 test<size_t>(); 142 143 return 0; 144 } 145