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