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[libc++] Split __shared_count out of <__memory/shared_ptr.h> (#115943)
`__shared_count` is used in a few places where `shared_ptr` isn't. This avoids a bunch of transitive includes needed for the implementation of `shared_ptr` in these places.
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8 files changed

+142
-117
lines changed

8 files changed

+142
-117
lines changed

‎libcxx/include/CMakeLists.txt

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@@ -557,6 +557,7 @@ set(files
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__memory/ranges_construct_at.h
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__memory/ranges_uninitialized_algorithms.h
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__memory/raw_storage_iterator.h
560+
__memory/shared_count.h
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__memory/shared_ptr.h
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__memory/swap_allocator.h
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__memory/temp_value.h

‎libcxx/include/__locale

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@@ -12,7 +12,7 @@
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#include <__config>
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#include <__locale_dir/locale_base_api.h>
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#include <__memory/shared_ptr.h> // __shared_count
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#include <__memory/shared_count.h>
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#include <__mutex/once_flag.h>
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#include <__type_traits/make_unsigned.h>
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#include <__utility/no_destroy.h>

‎libcxx/include/__memory/shared_count.h

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@@ -0,0 +1,136 @@
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//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___MEMORY_SHARED_COUNT_H
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#define _LIBCPP___MEMORY_SHARED_COUNT_H
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#include <__config>
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#include <typeinfo>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_BEGIN_NAMESPACE_STD
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// NOTE: Relaxed and acq/rel atomics (for increment and decrement respectively)
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// should be sufficient for thread safety.
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// See https://llvm.org/PR22803
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#if (defined(__clang__) && __has_builtin(__atomic_add_fetch) && defined(__ATOMIC_RELAXED) && \
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defined(__ATOMIC_ACQ_REL)) || \
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defined(_LIBCPP_COMPILER_GCC)
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# define _LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT 1
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#else
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# define _LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT 0
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#endif
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template <class _ValueType>
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inline _LIBCPP_HIDE_FROM_ABI _ValueType __libcpp_relaxed_load(_ValueType const* __value) {
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#if _LIBCPP_HAS_THREADS && defined(__ATOMIC_RELAXED) && \
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(__has_builtin(__atomic_load_n) || defined(_LIBCPP_COMPILER_GCC))
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return __atomic_load_n(__value, __ATOMIC_RELAXED);
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#else
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return *__value;
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#endif
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}
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template <class _ValueType>
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inline _LIBCPP_HIDE_FROM_ABI _ValueType __libcpp_acquire_load(_ValueType const* __value) {
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#if _LIBCPP_HAS_THREADS && defined(__ATOMIC_ACQUIRE) && \
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(__has_builtin(__atomic_load_n) || defined(_LIBCPP_COMPILER_GCC))
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return __atomic_load_n(__value, __ATOMIC_ACQUIRE);
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#else
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return *__value;
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#endif
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}
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template <class _Tp>
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inline _LIBCPP_HIDE_FROM_ABI _Tp __libcpp_atomic_refcount_increment(_Tp& __t) _NOEXCEPT {
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#if _LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT && _LIBCPP_HAS_THREADS
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return __atomic_add_fetch(&__t, 1, __ATOMIC_RELAXED);
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#else
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return __t += 1;
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#endif
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}
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template <class _Tp>
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inline _LIBCPP_HIDE_FROM_ABI _Tp __libcpp_atomic_refcount_decrement(_Tp& __t) _NOEXCEPT {
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#if _LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT && _LIBCPP_HAS_THREADS
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return __atomic_add_fetch(&__t, -1, __ATOMIC_ACQ_REL);
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#else
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return __t -= 1;
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#endif
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}
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class _LIBCPP_EXPORTED_FROM_ABI __shared_count {
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__shared_count(const __shared_count&);
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__shared_count& operator=(const __shared_count&);
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protected:
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long __shared_owners_;
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virtual ~__shared_count();
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private:
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virtual void __on_zero_shared() _NOEXCEPT = 0;
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public:
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_LIBCPP_HIDE_FROM_ABI explicit __shared_count(long __refs = 0) _NOEXCEPT : __shared_owners_(__refs) {}
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#if defined(_LIBCPP_SHARED_PTR_DEFINE_LEGACY_INLINE_FUNCTIONS)
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void __add_shared() noexcept;
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bool __release_shared() noexcept;
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#else
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_LIBCPP_HIDE_FROM_ABI void __add_shared() _NOEXCEPT { __libcpp_atomic_refcount_increment(__shared_owners_); }
89+
_LIBCPP_HIDE_FROM_ABI bool __release_shared() _NOEXCEPT {
90+
if (__libcpp_atomic_refcount_decrement(__shared_owners_) == -1) {
91+
__on_zero_shared();
92+
return true;
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}
94+
return false;
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}
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#endif
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_LIBCPP_HIDE_FROM_ABI long use_count() const _NOEXCEPT { return __libcpp_relaxed_load(&__shared_owners_) + 1; }
98+
};
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class _LIBCPP_EXPORTED_FROM_ABI __shared_weak_count : private __shared_count {
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long __shared_weak_owners_;
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public:
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_LIBCPP_HIDE_FROM_ABI explicit __shared_weak_count(long __refs = 0) _NOEXCEPT
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: __shared_count(__refs),
106+
__shared_weak_owners_(__refs) {}
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protected:
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~__shared_weak_count() override;
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public:
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#if defined(_LIBCPP_SHARED_PTR_DEFINE_LEGACY_INLINE_FUNCTIONS)
113+
void __add_shared() noexcept;
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void __add_weak() noexcept;
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void __release_shared() noexcept;
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#else
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_LIBCPP_HIDE_FROM_ABI void __add_shared() _NOEXCEPT { __shared_count::__add_shared(); }
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_LIBCPP_HIDE_FROM_ABI void __add_weak() _NOEXCEPT { __libcpp_atomic_refcount_increment(__shared_weak_owners_); }
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_LIBCPP_HIDE_FROM_ABI void __release_shared() _NOEXCEPT {
120+
if (__shared_count::__release_shared())
121+
__release_weak();
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}
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#endif
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void __release_weak() _NOEXCEPT;
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_LIBCPP_HIDE_FROM_ABI long use_count() const _NOEXCEPT { return __shared_count::use_count(); }
126+
__shared_weak_count* lock() _NOEXCEPT;
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virtual const void* __get_deleter(const type_info&) const _NOEXCEPT;
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private:
131+
virtual void __on_zero_shared_weak() _NOEXCEPT = 0;
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};
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___MEMORY_SHARED_COUNT_H

‎libcxx/include/__memory/shared_ptr.h

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@@ -30,6 +30,7 @@
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#include <__memory/compressed_pair.h>
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#include <__memory/construct_at.h>
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#include <__memory/pointer_traits.h>
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#include <__memory/shared_count.h>
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#include <__memory/uninitialized_algorithms.h>
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#include <__memory/unique_ptr.h>
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#include <__type_traits/add_lvalue_reference.h>
@@ -70,55 +71,6 @@ _LIBCPP_PUSH_MACROS
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_LIBCPP_BEGIN_NAMESPACE_STD
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73-
// NOTE: Relaxed and acq/rel atomics (for increment and decrement respectively)
74-
// should be sufficient for thread safety.
75-
// See https://llvm.org/PR22803
76-
#if (defined(__clang__) && __has_builtin(__atomic_add_fetch) && defined(__ATOMIC_RELAXED) && \
77-
defined(__ATOMIC_ACQ_REL)) || \
78-
defined(_LIBCPP_COMPILER_GCC)
79-
# define _LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT 1
80-
#else
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# define _LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT 0
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#endif
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template <class _ValueType>
85-
inline _LIBCPP_HIDE_FROM_ABI _ValueType __libcpp_relaxed_load(_ValueType const* __value) {
86-
#if _LIBCPP_HAS_THREADS && defined(__ATOMIC_RELAXED) && \
87-
(__has_builtin(__atomic_load_n) || defined(_LIBCPP_COMPILER_GCC))
88-
return __atomic_load_n(__value, __ATOMIC_RELAXED);
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#else
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return *__value;
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#endif
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}
93-
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template <class _ValueType>
95-
inline _LIBCPP_HIDE_FROM_ABI _ValueType __libcpp_acquire_load(_ValueType const* __value) {
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#if _LIBCPP_HAS_THREADS && defined(__ATOMIC_ACQUIRE) && \
97-
(__has_builtin(__atomic_load_n) || defined(_LIBCPP_COMPILER_GCC))
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return __atomic_load_n(__value, __ATOMIC_ACQUIRE);
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#else
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return *__value;
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#endif
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}
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template <class _Tp>
105-
inline _LIBCPP_HIDE_FROM_ABI _Tp __libcpp_atomic_refcount_increment(_Tp& __t) _NOEXCEPT {
106-
#if _LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT && _LIBCPP_HAS_THREADS
107-
return __atomic_add_fetch(&__t, 1, __ATOMIC_RELAXED);
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#else
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return __t += 1;
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#endif
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}
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template <class _Tp>
114-
inline _LIBCPP_HIDE_FROM_ABI _Tp __libcpp_atomic_refcount_decrement(_Tp& __t) _NOEXCEPT {
115-
#if _LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT && _LIBCPP_HAS_THREADS
116-
return __atomic_add_fetch(&__t, -1, __ATOMIC_ACQ_REL);
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#else
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return __t -= 1;
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#endif
120-
}
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class _LIBCPP_EXPORTED_FROM_ABI bad_weak_ptr : public std::exception {
12375
public:
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_LIBCPP_HIDE_FROM_ABI bad_weak_ptr() _NOEXCEPT = default;
@@ -139,70 +91,6 @@ class _LIBCPP_EXPORTED_FROM_ABI bad_weak_ptr : public std::exception {
13991
template <class _Tp>
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class _LIBCPP_TEMPLATE_VIS weak_ptr;
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142-
class _LIBCPP_EXPORTED_FROM_ABI __shared_count {
143-
__shared_count(const __shared_count&);
144-
__shared_count& operator=(const __shared_count&);
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protected:
147-
long __shared_owners_;
148-
virtual ~__shared_count();
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private:
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virtual void __on_zero_shared() _NOEXCEPT = 0;
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public:
154-
_LIBCPP_HIDE_FROM_ABI explicit __shared_count(long __refs = 0) _NOEXCEPT : __shared_owners_(__refs) {}
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#if defined(_LIBCPP_SHARED_PTR_DEFINE_LEGACY_INLINE_FUNCTIONS)
157-
void __add_shared() noexcept;
158-
bool __release_shared() noexcept;
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#else
160-
_LIBCPP_HIDE_FROM_ABI void __add_shared() _NOEXCEPT { __libcpp_atomic_refcount_increment(__shared_owners_); }
161-
_LIBCPP_HIDE_FROM_ABI bool __release_shared() _NOEXCEPT {
162-
if (__libcpp_atomic_refcount_decrement(__shared_owners_) == -1) {
163-
__on_zero_shared();
164-
return true;
165-
}
166-
return false;
167-
}
168-
#endif
169-
_LIBCPP_HIDE_FROM_ABI long use_count() const _NOEXCEPT { return __libcpp_relaxed_load(&__shared_owners_) + 1; }
170-
};
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class _LIBCPP_EXPORTED_FROM_ABI __shared_weak_count : private __shared_count {
173-
long __shared_weak_owners_;
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public:
176-
_LIBCPP_HIDE_FROM_ABI explicit __shared_weak_count(long __refs = 0) _NOEXCEPT
177-
: __shared_count(__refs),
178-
__shared_weak_owners_(__refs) {}
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protected:
181-
~__shared_weak_count() override;
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public:
184-
#if defined(_LIBCPP_SHARED_PTR_DEFINE_LEGACY_INLINE_FUNCTIONS)
185-
void __add_shared() noexcept;
186-
void __add_weak() noexcept;
187-
void __release_shared() noexcept;
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#else
189-
_LIBCPP_HIDE_FROM_ABI void __add_shared() _NOEXCEPT { __shared_count::__add_shared(); }
190-
_LIBCPP_HIDE_FROM_ABI void __add_weak() _NOEXCEPT { __libcpp_atomic_refcount_increment(__shared_weak_owners_); }
191-
_LIBCPP_HIDE_FROM_ABI void __release_shared() _NOEXCEPT {
192-
if (__shared_count::__release_shared())
193-
__release_weak();
194-
}
195-
#endif
196-
void __release_weak() _NOEXCEPT;
197-
_LIBCPP_HIDE_FROM_ABI long use_count() const _NOEXCEPT { return __shared_count::use_count(); }
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__shared_weak_count* lock() _NOEXCEPT;
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virtual const void* __get_deleter(const type_info&) const _NOEXCEPT;
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private:
203-
virtual void __on_zero_shared_weak() _NOEXCEPT = 0;
204-
};
205-
20694
template <class _Tp, class _Dp, class _Alloc>
20795
class __shared_ptr_pointer : public __shared_weak_count {
20896
_LIBCPP_COMPRESSED_TRIPLE(_Tp, __ptr_, _Dp, __deleter_, _Alloc, __alloc_);

‎libcxx/include/__mutex/once_flag.h

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@@ -11,7 +11,7 @@
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#include <__config>
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#include <__functional/invoke.h>
14-
#include <__memory/shared_ptr.h> // __libcpp_acquire_load
14+
#include <__memory/shared_count.h> // __libcpp_acquire_load
1515
#include <__tuple/tuple_indices.h>
1616
#include <__tuple/tuple_size.h>
1717
#include <__utility/forward.h>

‎libcxx/include/future

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@@ -378,7 +378,7 @@ template <class R, class Alloc> struct uses_allocator<packaged_task<R>, Alloc>;
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# include <__memory/allocator_traits.h>
379379
# include <__memory/compressed_pair.h>
380380
# include <__memory/pointer_traits.h>
381-
# include <__memory/shared_ptr.h>
381+
# include <__memory/shared_count.h>
382382
# include <__memory/unique_ptr.h>
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# include <__memory/uses_allocator.h>
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# include <__system_error/error_category.h>

‎libcxx/include/module.modulemap

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@@ -1542,6 +1542,7 @@ module std [system] {
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export std.algorithm.in_out_result
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}
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module raw_storage_iterator { header "__memory/raw_storage_iterator.h" }
1545+
module shared_count { header "__memory/shared_count.h" }
15451546
module shared_ptr { header "__memory/shared_ptr.h" }
15461547
module swap_allocator { header "__memory/swap_allocator.h" }
15471548
module temp_value { header "__memory/temp_value.h" }

‎libcxx/include/mutex

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@@ -190,7 +190,6 @@ template<class Callable, class ...Args>
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#include <__chrono/time_point.h>
191191
#include <__condition_variable/condition_variable.h>
192192
#include <__config>
193-
#include <__memory/shared_ptr.h>
194193
#include <__mutex/lock_guard.h>
195194
#include <__mutex/mutex.h>
196195
#include <__mutex/once_flag.h>

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