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