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 countl_one(T x) noexcept;
13 
14 // Constraints: T is an unsigned integer type
15 // The number of consecutive 1 bits, starting from the most significant bit.
16 //   [ Note: Returns N if x == std::numeric_limits<T>::max(). ]
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::countl_one(T())), int);
33     ASSERT_NOEXCEPT(std::countl_one(T()));
34     T max = std::numeric_limits<T>::max();
35 
36     assert(std::countl_one(T(0)) == 0);
37     assert(std::countl_one(T(1)) == 0);
38     assert(std::countl_one(T(10)) == 0);
39     assert(std::countl_one(T(100)) == 0);
40     assert(std::countl_one(max) == std::numeric_limits<T>::digits);
41     assert(std::countl_one(T(max - 1)) == std::numeric_limits<T>::digits - 1);
42     assert(std::countl_one(T(max - 2)) == std::numeric_limits<T>::digits - 2);
43     assert(std::countl_one(T(max - 3)) == std::numeric_limits<T>::digits - 2);
44     assert(std::countl_one(T(max - 4)) == std::numeric_limits<T>::digits - 3);
45     assert(std::countl_one(T(max - 5)) == std::numeric_limits<T>::digits - 3);
46     assert(std::countl_one(T(max - 6)) == std::numeric_limits<T>::digits - 3);
47     assert(std::countl_one(T(max - 7)) == std::numeric_limits<T>::digits - 3);
48     assert(std::countl_one(T(max - 8)) == std::numeric_limits<T>::digits - 4);
49     assert(std::countl_one(T(max - 9)) == std::numeric_limits<T>::digits - 4);
50     assert(std::countl_one(T(max - 126)) == std::numeric_limits<T>::digits - 7);
51     assert(std::countl_one(T(max - 127)) == std::numeric_limits<T>::digits - 7);
52     assert(std::countl_one(T(max - 128)) == std::numeric_limits<T>::digits - 8);
53 
54 #ifndef _LIBCPP_HAS_NO_INT128
55     if constexpr (std::is_same_v<T, __uint128_t>) {
56         T val = 128;
57         assert(std::countl_one(~val) == 120);
58         val <<= 32;
59         assert(std::countl_one(~val) == 88);
60         val <<= 60;
61         assert(std::countl_one(~val) == 28);
62     }
63 #endif
64 
65     return true;
66 }
67 
68 int main(int, char**)
69 {
70     {
71     auto lambda = [](auto x) -> decltype(std::countl_one(x)) {};
72     using L = decltype(lambda);
73 
74     static_assert(!std::is_invocable_v<L, signed char>);
75     static_assert(!std::is_invocable_v<L, short>);
76     static_assert(!std::is_invocable_v<L, int>);
77     static_assert(!std::is_invocable_v<L, long>);
78     static_assert(!std::is_invocable_v<L, long long>);
79 #ifndef _LIBCPP_HAS_NO_INT128
80     static_assert(!std::is_invocable_v<L, __int128_t>);
81 #endif
82 
83     static_assert(!std::is_invocable_v<L, int8_t>);
84     static_assert(!std::is_invocable_v<L, int16_t>);
85     static_assert(!std::is_invocable_v<L, int32_t>);
86     static_assert(!std::is_invocable_v<L, int64_t>);
87     static_assert(!std::is_invocable_v<L, intmax_t>);
88     static_assert(!std::is_invocable_v<L, intptr_t>);
89     static_assert(!std::is_invocable_v<L, ptrdiff_t>);
90 
91     static_assert(!std::is_invocable_v<L, bool>);
92     static_assert(!std::is_invocable_v<L, char>);
93     static_assert(!std::is_invocable_v<L, wchar_t>);
94 #ifndef _LIBCPP_HAS_NO_CHAR8_T
95     static_assert(!std::is_invocable_v<L, char8_t>);
96 #endif
97     static_assert(!std::is_invocable_v<L, char16_t>);
98     static_assert(!std::is_invocable_v<L, char32_t>);
99 
100     static_assert(!std::is_invocable_v<L, A>);
101     static_assert(!std::is_invocable_v<L, A*>);
102     static_assert(!std::is_invocable_v<L, E1>);
103     static_assert(!std::is_invocable_v<L, E2>);
104     }
105 
106     static_assert(test<unsigned char>());
107     static_assert(test<unsigned short>());
108     static_assert(test<unsigned int>());
109     static_assert(test<unsigned long>());
110     static_assert(test<unsigned long long>());
111 #ifndef _LIBCPP_HAS_NO_INT128
112     static_assert(test<__uint128_t>());
113 #endif
114     static_assert(test<uint8_t>());
115     static_assert(test<uint16_t>());
116     static_assert(test<uint32_t>());
117     static_assert(test<uint64_t>());
118     static_assert(test<uintmax_t>());
119     static_assert(test<uintptr_t>());
120     static_assert(test<size_t>());
121 
122     test<unsigned char>();
123     test<unsigned short>();
124     test<unsigned int>();
125     test<unsigned long>();
126     test<unsigned long long>();
127 #ifndef _LIBCPP_HAS_NO_INT128
128     test<__uint128_t>();
129 #endif
130     test<uint8_t>();
131     test<uint16_t>();
132     test<uint32_t>();
133     test<uint64_t>();
134     test<uintmax_t>();
135     test<uintptr_t>();
136     test<size_t>();
137 
138     return 0;
139 }
140 
141