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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// TODO: __builtin_popcountg is available since Clang 19 and GCC 14. When support for older versions is dropped, we can
// refactor this code to exclusively use __builtin_popcountg.
#ifndef _LIBCPP___CXX03___BIT_POPCOUNT_H
#define _LIBCPP___CXX03___BIT_POPCOUNT_H
#include <__cxx03/__bit/rotate.h>
#include <__cxx03/__concepts/arithmetic.h>
#include <__cxx03/__config>
#include <__cxx03/limits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__cxx03/__undef_macros>
_LIBCPP_BEGIN_NAMESPACE_STD
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR int __libcpp_popcount(unsigned __x) _NOEXCEPT {
return __builtin_popcount(__x);
}
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR int __libcpp_popcount(unsigned long __x) _NOEXCEPT {
return __builtin_popcountl(__x);
}
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR int __libcpp_popcount(unsigned long long __x) _NOEXCEPT {
return __builtin_popcountll(__x);
}
#if _LIBCPP_STD_VER >= 20
template <__libcpp_unsigned_integer _Tp>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr int popcount(_Tp __t) noexcept {
# if __has_builtin(__builtin_popcountg)
return __builtin_popcountg(__t);
# else // __has_builtin(__builtin_popcountg)
if (sizeof(_Tp) <= sizeof(unsigned int))
return std::__libcpp_popcount(static_cast<unsigned int>(__t));
else if (sizeof(_Tp) <= sizeof(unsigned long))
return std::__libcpp_popcount(static_cast<unsigned long>(__t));
else if (sizeof(_Tp) <= sizeof(unsigned long long))
return std::__libcpp_popcount(static_cast<unsigned long long>(__t));
else {
int __ret = 0;
while (__t != 0) {
__ret += std::__libcpp_popcount(static_cast<unsigned long long>(__t));
__t >>= numeric_limits<unsigned long long>::digits;
}
return __ret;
}
# endif // __has_builtin(__builtin_popcountg)
}
#endif // _LIBCPP_STD_VER >= 20
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___CXX03___BIT_POPCOUNT_H
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