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#ifndef _LIBCPP___BIT_POPCOUNT_H
10#define _LIBCPP___BIT_POPCOUNT_H
11
12#include <__config>
13#include <__type_traits/integer_traits.h>
14
15#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
16# pragma GCC system_header
17#endif
18
19_LIBCPP_PUSH_MACROS
20#include <__undef_macros>
21
22_LIBCPP_BEGIN_NAMESPACE_STD
23
24template <class _Tp>
25[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR int __popcount(_Tp __t) _NOEXCEPT {
26 static_assert(__is_unsigned_integer_v<_Tp>, "__popcount only works with unsigned types");
27 return __builtin_popcountg(__t);
28}
29
30#if _LIBCPP_STD_VER >= 20
31
32template <__unsigned_integer _Tp>
33[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr int popcount(_Tp __t) noexcept {
34 return std::__popcount(__t);
35}
36
37#endif
38
39_LIBCPP_END_NAMESPACE_STD
40
41_LIBCPP_POP_MACROS
42
43#endif // _LIBCPP___BIT_POPCOUNT_H
44