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 countr_zero(T x) noexcept; 13 14 // Constraints: T is an unsigned integer type 15 // Returns: The number of consecutive 0 bits, starting from the most significant bit. 16 // [ Note: Returns N if x == 0. ] 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::countr_zero(T())), int); 35 ASSERT_NOEXCEPT(std::countr_zero(T())); 36 T max = std::numeric_limits<T>::max(); 37 38 assert(std::countr_zero(T(0)) == std::numeric_limits<T>::digits); 39 assert(std::countr_zero(T(1)) == 0); 40 assert(std::countr_zero(T(2)) == 1); 41 assert(std::countr_zero(T(3)) == 0); 42 assert(std::countr_zero(T(4)) == 2); 43 assert(std::countr_zero(T(5)) == 0); 44 assert(std::countr_zero(T(6)) == 1); 45 assert(std::countr_zero(T(7)) == 0); 46 assert(std::countr_zero(T(8)) == 3); 47 assert(std::countr_zero(T(9)) == 0); 48 assert(std::countr_zero(T(126)) == 1); 49 assert(std::countr_zero(T(127)) == 0); 50 assert(std::countr_zero(T(128)) == 7); 51 assert(std::countr_zero(T(129)) == 0); 52 assert(std::countr_zero(T(130)) == 1); 53 assert(std::countr_zero(max) == 0); 54 55 #ifndef TEST_HAS_NO_INT128 56 if constexpr (std::is_same_v<T, __uint128_t>) { 57 T val = T(128) << 32; 58 assert(std::countr_zero(val-1) == 0); 59 assert(std::countr_zero(val) == 39); 60 assert(std::countr_zero(val+1) == 0); 61 val <<= 60; 62 assert(std::countr_zero(val-1) == 0); 63 assert(std::countr_zero(val) == 99); 64 assert(std::countr_zero(val+1) == 0); 65 } 66 #endif 67 68 return true; 69 } 70 71 int main(int, char**) 72 { 73 { 74 auto lambda = [](auto x) -> decltype(std::countr_zero(x)) {}; 75 using L = decltype(lambda); 76 77 static_assert(!std::is_invocable_v<L, signed char>); 78 static_assert(!std::is_invocable_v<L, short>); 79 static_assert(!std::is_invocable_v<L, int>); 80 static_assert(!std::is_invocable_v<L, long>); 81 static_assert(!std::is_invocable_v<L, long long>); 82 #ifndef TEST_HAS_NO_INT128 83 static_assert(!std::is_invocable_v<L, __int128_t>); 84 #endif 85 86 static_assert(!std::is_invocable_v<L, std::int8_t>); 87 static_assert(!std::is_invocable_v<L, std::int16_t>); 88 static_assert(!std::is_invocable_v<L, std::int32_t>); 89 static_assert(!std::is_invocable_v<L, std::int64_t>); 90 static_assert(!std::is_invocable_v<L, std::intmax_t>); 91 static_assert(!std::is_invocable_v<L, std::intptr_t>); 92 static_assert(!std::is_invocable_v<L, std::ptrdiff_t>); 93 94 static_assert(!std::is_invocable_v<L, bool>); 95 static_assert(!std::is_invocable_v<L, char>); 96 static_assert(!std::is_invocable_v<L, wchar_t>); 97 #ifndef TEST_HAS_NO_CHAR8_T 98 static_assert(!std::is_invocable_v<L, char8_t>); 99 #endif 100 static_assert(!std::is_invocable_v<L, char16_t>); 101 static_assert(!std::is_invocable_v<L, char32_t>); 102 103 static_assert(!std::is_invocable_v<L, A>); 104 static_assert(!std::is_invocable_v<L, A*>); 105 static_assert(!std::is_invocable_v<L, E1>); 106 static_assert(!std::is_invocable_v<L, E2>); 107 } 108 109 static_assert(test<unsigned char>()); 110 static_assert(test<unsigned short>()); 111 static_assert(test<unsigned int>()); 112 static_assert(test<unsigned long>()); 113 static_assert(test<unsigned long long>()); 114 #ifndef TEST_HAS_NO_INT128 115 static_assert(test<__uint128_t>()); 116 #endif 117 static_assert(test<std::uint8_t>()); 118 static_assert(test<std::uint16_t>()); 119 static_assert(test<std::uint32_t>()); 120 static_assert(test<std::uint64_t>()); 121 static_assert(test<std::uintmax_t>()); 122 static_assert(test<std::uintptr_t>()); 123 static_assert(test<std::size_t>()); 124 125 test<unsigned char>(); 126 test<unsigned short>(); 127 test<unsigned int>(); 128 test<unsigned long>(); 129 test<unsigned long long>(); 130 #ifndef TEST_HAS_NO_INT128 131 test<__uint128_t>(); 132 #endif 133 test<std::uint8_t>(); 134 test<std::uint16_t>(); 135 test<std::uint32_t>(); 136 test<std::uint64_t>(); 137 test<std::uintmax_t>(); 138 test<std::uintptr_t>(); 139 test<std::size_t>(); 140 141 return 0; 142 } 143