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[libc++] Replace __libcpp_popcount by __builtin_popcountg #133937

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merged 1 commit into from
Apr 13, 2025
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[libc++] Replace __libcpp_popcount by __builtin_popcountg #133937

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43 changes: 0 additions & 43 deletions libcxx/include/__bit/popcount.h
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Original file line number Diff line number Diff line change
Expand Up @@ -6,9 +6,6 @@
//
//===----------------------------------------------------------------------===//

// 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___BIT_POPCOUNT_H
#define _LIBCPP___BIT_POPCOUNT_H

Expand All @@ -27,50 +24,10 @@ _LIBCPP_PUSH_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);
}

template <class _Tp>
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR int __popcount_impl(_Tp __t) _NOEXCEPT {
if _LIBCPP_CONSTEXPR (sizeof(_Tp) <= sizeof(unsigned int)) {
return std::__libcpp_popcount(static_cast<unsigned int>(__t));
} else if _LIBCPP_CONSTEXPR (sizeof(_Tp) <= sizeof(unsigned long)) {
return std::__libcpp_popcount(static_cast<unsigned long>(__t));
} else if _LIBCPP_CONSTEXPR (sizeof(_Tp) <= sizeof(unsigned long long)) {
return std::__libcpp_popcount(static_cast<unsigned long long>(__t));
} else {
#if _LIBCPP_STD_VER == 11
return __t != 0 ? std::__libcpp_popcount(static_cast<unsigned long long>(__t)) +
std::__popcount_impl<_Tp>(__t >> numeric_limits<unsigned long long>::digits)
: 0;
#else
int __ret = 0;
while (__t != 0) {
__ret += std::__libcpp_popcount(static_cast<unsigned long long>(__t));
__t >>= std::numeric_limits<unsigned long long>::digits;
}
return __ret;
#endif
}
}

template <class _Tp>
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR int __popcount(_Tp __t) _NOEXCEPT {
static_assert(is_unsigned<_Tp>::value, "__popcount only works with unsigned types");
#if __has_builtin(__builtin_popcountg) // TODO (LLVM 21): This can be dropped once we only support Clang >= 19.
return __builtin_popcountg(__t);
#else
return std::__popcount_impl(__t);
#endif
}

#if _LIBCPP_STD_VER >= 20
Expand Down
2 changes: 1 addition & 1 deletion libcxx/include/__stop_token/atomic_unique_lock.h
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@ _LIBCPP_BEGIN_NAMESPACE_STD
// and LockedBit is the value of State when the lock bit is set, e.g 1 << 2
template <class _State, _State _LockedBit>
class _LIBCPP_AVAILABILITY_SYNC __atomic_unique_lock {
static_assert(std::__libcpp_popcount(static_cast<unsigned long long>(_LockedBit)) == 1,
static_assert(std::__popcount(static_cast<unsigned long long>(_LockedBit)) == 1,
"LockedBit must be an integer where only one bit is set");

std::atomic<_State>& __state_;
Expand Down