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