[libcxx-commits] [libcxx] [libc++] Implement P0718R2: `atomic<shared_ptr<T>>` (PR #78317)
Mital Ashok via libcxx-commits
libcxx-commits at lists.llvm.org
Tue Jan 16 09:37:57 PST 2024
https://github.com/MitalAshok created https://github.com/llvm/llvm-project/pull/78317
Implements [P0718R2](https://wg21.link/P0718R2).
This is quite a "dumb" implementation: It just reuses the now-deprecated functions in [[depr.util.smartptr.shared.atomic]](https://wg21.link/depr.util.smartptr.shared.atomic) on a held `std::{shared/weak}_ptr<T>` member.
[P1644R0](https://wg21.link/P1644R0) (`wait`/`notify` for `atomic<shared_ptr<T>>`) is *not* implemented. I will work on a subsequent patch, but we need `atomic<shared_ptr>` first.
I also noticed [LWG3661](https://wg21.link/LWG3661) (`constinit atomic<shared_ptr<T>> a(nullptr);`) did not apply to `atomic<weak_ptr<T>>`, but I see no reason not to support it.
I also added forward declarations for the partial specializations in `<atomic>`. This shouldn't change the correctness of any code but should give a better error (that `atomic<shared_ptr<T>>` is incomplete, not that `shared_ptr<T>` is a non-trivial type in the primary template)
>From db262ab8349420ca2f4e7144a0deb9218fa18ed0 Mon Sep 17 00:00:00 2001
From: Mital Ashok <mital at mitalashok.co.uk>
Date: Tue, 16 Jan 2024 16:26:39 +0000
Subject: [PATCH] [libc++] Implement P0718R2: atomic<shared_ptr<T>>
Also implemented LWG3661, LWG3893
---
libcxx/docs/FeatureTestMacroTable.rst | 2 +-
libcxx/docs/ReleaseNotes/18.rst | 1 +
libcxx/docs/Status/Cxx20Papers.csv | 2 +-
libcxx/docs/Status/Cxx23Issues.csv | 2 +-
libcxx/docs/Status/Cxx2cIssues.csv | 2 +-
libcxx/include/CMakeLists.txt | 1 +
libcxx/include/__atomic/atomic.h | 10 +
libcxx/include/__memory/atomic_shared_ptr.h | 233 ++++++++++++++++++
libcxx/include/__memory/shared_ptr.h | 104 --------
libcxx/include/memory | 93 ++++++-
libcxx/include/module.modulemap.in | 1 +
libcxx/include/version | 2 +-
libcxx/modules/std/memory.inc | 3 +
libcxx/test/std/atomics/types.pass.cpp | 3 +-
.../atomic.version.compile.pass.cpp | 48 ++--
.../version.version.compile.pass.cpp | 48 ++--
.../generate_feature_test_macro_components.py | 1 -
17 files changed, 368 insertions(+), 188 deletions(-)
create mode 100644 libcxx/include/__memory/atomic_shared_ptr.h
diff --git a/libcxx/docs/FeatureTestMacroTable.rst b/libcxx/docs/FeatureTestMacroTable.rst
index 893a3b13ca06e0..ea411ee8d67277 100644
--- a/libcxx/docs/FeatureTestMacroTable.rst
+++ b/libcxx/docs/FeatureTestMacroTable.rst
@@ -180,7 +180,7 @@ Status
--------------------------------------------------- -----------------
``__cpp_lib_atomic_ref`` *unimplemented*
--------------------------------------------------- -----------------
- ``__cpp_lib_atomic_shared_ptr`` *unimplemented*
+ ``__cpp_lib_atomic_shared_ptr`` ``201711L``
--------------------------------------------------- -----------------
``__cpp_lib_atomic_value_initialization`` ``201911L``
--------------------------------------------------- -----------------
diff --git a/libcxx/docs/ReleaseNotes/18.rst b/libcxx/docs/ReleaseNotes/18.rst
index 62a1fec627d0ca..c6efadd4ba1e20 100644
--- a/libcxx/docs/ReleaseNotes/18.rst
+++ b/libcxx/docs/ReleaseNotes/18.rst
@@ -60,6 +60,7 @@ Implemented Papers
- P0521R0 - Proposed Resolution for CA 14 (``shared_ptr`` ``use_count/unique``)
- P1759R6 - Native handles and file streams
- P2517R1 - Add a conditional ``noexcept`` specification to ``std::apply``
+- P0718R2 - Revising ``atomic_shared_ptr`` for C++20
Improvements and New Features
diff --git a/libcxx/docs/Status/Cxx20Papers.csv b/libcxx/docs/Status/Cxx20Papers.csv
index d73088687975c2..eae002a35d3345 100644
--- a/libcxx/docs/Status/Cxx20Papers.csv
+++ b/libcxx/docs/Status/Cxx20Papers.csv
@@ -12,7 +12,7 @@
"`P0600R1 <https://wg21.link/P0600R1>`__","LWG","nodiscard in the Library","Albuquerque","|Complete|","16.0"
"`P0616R0 <https://wg21.link/P0616R0>`__","LWG","de-pessimize legacy <numeric> algorithms with std::move","Albuquerque","|Complete|","12.0"
"`P0653R2 <https://wg21.link/P0653R2>`__","LWG","Utility to convert a pointer to a raw pointer","Albuquerque","|Complete|","6.0"
-"`P0718R2 <https://wg21.link/P0718R2>`__","LWG","Atomic shared_ptr","Albuquerque","",""
+"`P0718R2 <https://wg21.link/P0718R2>`__","LWG","Atomic shared_ptr","Albuquerque","|Complete|","18.0"
"`P0767R1 <https://wg21.link/P0767R1>`__","CWG","Deprecate POD","Albuquerque","|Complete|","7.0"
"`P0768R1 <https://wg21.link/P0768R1>`__","CWG","Library Support for the Spaceship (Comparison) Operator","Albuquerque","|Complete|",""
"`P0777R1 <https://wg21.link/P0777R1>`__","LWG","Treating Unnecessary ``decay``\ ","Albuquerque","|Complete|","7.0"
diff --git a/libcxx/docs/Status/Cxx23Issues.csv b/libcxx/docs/Status/Cxx23Issues.csv
index b24ecc5525a149..59786140903918 100644
--- a/libcxx/docs/Status/Cxx23Issues.csv
+++ b/libcxx/docs/Status/Cxx23Issues.csv
@@ -157,7 +157,7 @@
"`3654 <https://wg21.link/LWG3654>`__","``basic_format_context::arg(size_t)`` should be ``noexcept`` ","February 2022","|Complete|","15.0","|format|"
"`3657 <https://wg21.link/LWG3657>`__","``std::hash<std::filesystem::path>`` is not enabled","February 2022","|Complete|","17.0"
"`3660 <https://wg21.link/LWG3660>`__","``iterator_traits<common_iterator>::pointer`` should conform to ยง[iterator.traits]","February 2022","|Complete|","14.0","|ranges|"
-"`3661 <https://wg21.link/LWG3661>`__","``constinit atomic<shared_ptr<T>> a(nullptr);`` should work","February 2022","",""
+"`3661 <https://wg21.link/LWG3661>`__","``constinit atomic<shared_ptr<T>> a(nullptr);`` should work","February 2022","|Complete|","18.0"
"","","","","",""
"`3564 <https://wg21.link/LWG3564>`__","``transform_view::iterator<true>::value_type`` and ``iterator_category`` should use ``const F&``","July 2022","","","|ranges|"
"`3617 <https://wg21.link/LWG3617>`__","``function``/``packaged_task`` deduction guides and deducing ``this``","July 2022","",""
diff --git a/libcxx/docs/Status/Cxx2cIssues.csv b/libcxx/docs/Status/Cxx2cIssues.csv
index fe0f13f6e8cb2c..88a08b01d4982e 100644
--- a/libcxx/docs/Status/Cxx2cIssues.csv
+++ b/libcxx/docs/Status/Cxx2cIssues.csv
@@ -3,7 +3,7 @@
"`3884 <https://wg21.link/LWG3884>`__","``flat_foo`` is missing allocator-extended copy/move constructors","Varna June 2023","","","|flat_containers|"
"`3885 <https://wg21.link/LWG3885>`__","``op`` should be in [zombie.names]","Varna June 2023","|Nothing To Do|","",""
"`3887 <https://wg21.link/LWG3887>`__","Version macro for ``allocate_at_least``","Varna June 2023","","",""
-"`3893 <https://wg21.link/LWG3893>`__","LWG 3661 broke ``atomic<shared_ptr<T>> a; a = nullptr;``","Varna June 2023","","",""
+"`3893 <https://wg21.link/LWG3893>`__","LWG 3661 broke ``atomic<shared_ptr<T>> a; a = nullptr;``","Varna June 2023","|Complete|","18.0",""
"`3894 <https://wg21.link/LWG3894>`__","``generator::promise_type::yield_value(ranges::elements_of<Rng, Alloc>)`` should not be ``noexcept``","Varna June 2023","","",""
"`3903 <https://wg21.link/LWG3903>`__","span destructor is redundantly noexcept","Varna June 2023","|Complete|","7.0",""
"`3904 <https://wg21.link/LWG3904>`__","``lazy_split_view::outer-iterator``'s const-converting constructor isn't setting ``trailing_empty_``","Varna June 2023","","","|ranges|"
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index 0fe3ab44d2466e..0fd51788c75714 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -526,6 +526,7 @@ set(files
__memory/allocator_destructor.h
__memory/allocator_traits.h
__memory/assume_aligned.h
+ __memory/atomic_shared_ptr.h
__memory/auto_ptr.h
__memory/builtin_new_allocator.h
__memory/compressed_pair.h
diff --git a/libcxx/include/__atomic/atomic.h b/libcxx/include/__atomic/atomic.h
index 3dfb6937d0325e..da12b36568fb3b 100644
--- a/libcxx/include/__atomic/atomic.h
+++ b/libcxx/include/__atomic/atomic.h
@@ -249,6 +249,16 @@ struct atomic<_Tp> : __atomic_base<_Tp> {
_LIBCPP_HIDE_FROM_ABI _Tp operator-=(_Tp __op) noexcept { return fetch_sub(__op) - __op; }
};
+template <class _Tp>
+class shared_ptr;
+template <class _Tp>
+class weak_ptr;
+
+template <class _Tp>
+struct atomic<shared_ptr<_Tp>>;
+template <class _Tp>
+struct atomic<weak_ptr<_Tp>>;
+
#endif // _LIBCPP_STD_VER >= 20
// atomic_is_lock_free
diff --git a/libcxx/include/__memory/atomic_shared_ptr.h b/libcxx/include/__memory/atomic_shared_ptr.h
new file mode 100644
index 00000000000000..f3fa2260ac9104
--- /dev/null
+++ b/libcxx/include/__memory/atomic_shared_ptr.h
@@ -0,0 +1,233 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___MEMORY_ATOMIC_SHARED_PTR_H
+#define _LIBCPP___MEMORY_ATOMIC_SHARED_PTR_H
+
+#include <__memory/addressof.h>
+#include <__memory/shared_ptr.h>
+#include <cstddef>
+#if !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
+# include <__atomic/memory_order.h>
+#endif
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+# pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if !defined(_LIBCPP_HAS_NO_THREADS)
+
+class _LIBCPP_EXPORTED_FROM_ABI __sp_mut {
+ void* __lx_;
+
+public:
+ void lock() _NOEXCEPT;
+ void unlock() _NOEXCEPT;
+
+private:
+ _LIBCPP_CONSTEXPR __sp_mut(void*) _NOEXCEPT;
+ __sp_mut(const __sp_mut&);
+ __sp_mut& operator=(const __sp_mut&);
+
+ friend _LIBCPP_EXPORTED_FROM_ABI __sp_mut& __get_sp_mut(const void*);
+};
+
+_LIBCPP_EXPORTED_FROM_ABI __sp_mut& __get_sp_mut(const void*);
+
+template <class _Tp>
+_LIBCPP_HIDE_FROM_ABI _Tp __sp_atomic_load(const _Tp* __p) {
+ __sp_mut& __m = std::__get_sp_mut(__p);
+ __m.lock();
+ _Tp __q = *__p;
+ __m.unlock();
+ return __q;
+}
+
+template <class _Tp>
+_LIBCPP_HIDE_FROM_ABI void __sp_atomic_store(_Tp* __p, _Tp& __r) {
+ __sp_mut& __m = std::__get_sp_mut(__p);
+ __m.lock();
+ __p->swap(__r);
+ __m.unlock();
+}
+
+template <class _Tp>
+_LIBCPP_HIDE_FROM_ABI bool __sp_atomic_compare_exchange_strong(_Tp* __p, _Tp* __v, _Tp& __w) {
+ _Tp __temp;
+ __sp_mut& __m = std::__get_sp_mut(__p);
+ __m.lock();
+ if (__p->__owner_equivalent(*__v)) {
+ std::swap(__temp, *__p);
+ *__p = __w;
+ __m.unlock();
+ return true;
+ }
+ std::swap(__temp, *__v);
+ *__v = *__p;
+ __m.unlock();
+ return false;
+}
+
+template <class _Tp>
+_LIBCPP_HIDE_FROM_ABI _Tp __sp_atomic_exchange(_Tp* __p, _Tp& __r) {
+ __sp_mut& __m = std::__get_sp_mut(__p);
+ __m.lock();
+ __p->swap(__r);
+ __m.unlock();
+ return __r;
+}
+
+# if _LIBCPP_STD_VER >= 20
+template <class _Tp>
+struct atomic;
+
+template <class _Tp>
+struct __sp_atomic_base {
+ using value_type = _Tp;
+
+ static constexpr bool is_always_lock_free = false;
+ _LIBCPP_HIDE_FROM_ABI bool is_lock_free() const noexcept { return false; }
+
+ _LIBCPP_HIDE_FROM_ABI constexpr __sp_atomic_base() noexcept = default;
+ _LIBCPP_HIDE_FROM_ABI __sp_atomic_base(_Tp&& __d) noexcept : __p(std::move(__d)) {}
+ _LIBCPP_HIDE_FROM_ABI __sp_atomic_base(const __sp_atomic_base&) = delete;
+ _LIBCPP_HIDE_FROM_ABI void operator=(const __sp_atomic_base&) = delete;
+
+ _LIBCPP_HIDE_FROM_ABI _Tp load(memory_order = memory_order_seq_cst) noexcept {
+ return std::__sp_atomic_load(std::addressof(__p));
+ }
+ _LIBCPP_HIDE_FROM_ABI operator _Tp() const noexcept { return load(); }
+ _LIBCPP_HIDE_FROM_ABI void store(_Tp __d, memory_order = memory_order_seq_cst) noexcept {
+ std::__sp_atomic_store(std::addressof(__p), __d);
+ }
+ _LIBCPP_HIDE_FROM_ABI void operator=(_Tp __d) noexcept { std::__sp_atomic_store(std::addressof(__p), __d); }
+ _LIBCPP_HIDE_FROM_ABI void operator=(nullptr_t) noexcept { store(nullptr); }
+
+ _LIBCPP_HIDE_FROM_ABI _Tp exchange(_Tp __d, memory_order = memory_order_seq_cst) noexcept {
+ return std::__sp_atomic_exchange(std::addressof(__p), __d);
+ }
+ _LIBCPP_HIDE_FROM_ABI bool compare_exchange_weak(_Tp& __e, _Tp __d, memory_order, memory_order) noexcept {
+ return std::__sp_atomic_compare_exchange_strong(std::addressof(__p), std::addressof(__e), __d);
+ }
+ _LIBCPP_HIDE_FROM_ABI bool compare_exchange_strong(_Tp& __e, _Tp __d, memory_order, memory_order) noexcept {
+ return std::__sp_atomic_compare_exchange_strong(std::addressof(__p), std::addressof(__e), __d);
+ }
+ _LIBCPP_HIDE_FROM_ABI bool compare_exchange_weak(_Tp& __e, _Tp __d, memory_order = memory_order_seq_cst) noexcept {
+ return std::__sp_atomic_compare_exchange_strong(std::addressof(__p), std::addressof(__e), __d);
+ }
+ _LIBCPP_HIDE_FROM_ABI bool compare_exchange_strong(_Tp& __e, _Tp __d, memory_order = memory_order_seq_cst) noexcept {
+ return std::__sp_atomic_compare_exchange_strong(std::addressof(__p), std::addressof(__e), __d);
+ }
+
+ // P1644R0 not implemented
+ // void wait(_Tp old, memory_order order = memory_order::seq_cst) const noexcept;
+ // void notify_one() noexcept;
+ // void notify_all() noexcept;
+
+private:
+ _Tp __p;
+};
+
+template <class _Tp>
+struct atomic<shared_ptr<_Tp>> : __sp_atomic_base<shared_ptr<_Tp>> {
+ _LIBCPP_HIDE_FROM_ABI constexpr atomic() noexcept = default;
+ _LIBCPP_HIDE_FROM_ABI constexpr atomic(nullptr_t) noexcept : atomic() {}
+ _LIBCPP_HIDE_FROM_ABI atomic(shared_ptr<_Tp> desired) noexcept
+ : __sp_atomic_base<shared_ptr<_Tp>>(std::move(desired)) {}
+ _LIBCPP_HIDE_FROM_ABI atomic(const atomic&) = delete;
+
+ _LIBCPP_HIDE_FROM_ABI void operator=(const atomic&) = delete;
+ using __sp_atomic_base<shared_ptr<_Tp>>::operator=;
+};
+
+template <class _Tp>
+struct atomic<weak_ptr<_Tp>> : __sp_atomic_base<weak_ptr<_Tp>> {
+ _LIBCPP_HIDE_FROM_ABI constexpr atomic() noexcept = default;
+ _LIBCPP_HIDE_FROM_ABI constexpr atomic(nullptr_t) noexcept : atomic() {}
+ _LIBCPP_HIDE_FROM_ABI atomic(weak_ptr<_Tp> desired) noexcept : __sp_atomic_base<weak_ptr<_Tp>>(std::move(desired)) {}
+ _LIBCPP_HIDE_FROM_ABI atomic(const atomic&) = delete;
+
+ _LIBCPP_HIDE_FROM_ABI void operator=(const atomic&) = delete;
+ using __sp_atomic_base<weak_ptr<_Tp>>::operator=;
+};
+# endif // _LIBCPP_STD_VER >= 20
+
+// [depr.util.smartptr.shared.atomic]
+
+template <class _Tp>
+inline _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI bool atomic_is_lock_free(const shared_ptr<_Tp>*) {
+ return false;
+}
+
+template <class _Tp>
+_LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp>
+atomic_load(const shared_ptr<_Tp>* __p) {
+ return std::__sp_atomic_load(__p);
+}
+
+template <class _Tp>
+inline _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp>
+atomic_load_explicit(const shared_ptr<_Tp>* __p, memory_order) {
+ return std::atomic_load(__p);
+}
+
+template <class _Tp>
+_LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI void atomic_store(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r) {
+ std::__sp_atomic_store(__p, __r);
+}
+
+template <class _Tp>
+inline _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI void
+atomic_store_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r, memory_order) {
+ std::atomic_store(__p, __r);
+}
+
+template <class _Tp>
+_LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp>
+atomic_exchange(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r) {
+ return std::__sp_atomic_exchange(__p, __r);
+}
+
+template <class _Tp>
+inline _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp>
+atomic_exchange_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r, memory_order) {
+ return std::atomic_exchange(__p, std::move(__r));
+}
+
+template <class _Tp>
+_LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI bool
+atomic_compare_exchange_strong(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w) {
+ return std::__sp_atomic_compare_exchange_strong(__p, __v, __w);
+}
+
+template <class _Tp>
+inline _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI bool
+atomic_compare_exchange_weak(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w) {
+ return std::atomic_compare_exchange_strong(__p, __v, std::move(__w));
+}
+
+template <class _Tp>
+inline _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_strong_explicit(
+ shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w, memory_order, memory_order) {
+ return std::atomic_compare_exchange_strong(__p, __v, std::move(__w));
+}
+
+template <class _Tp>
+inline _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_weak_explicit(
+ shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w, memory_order, memory_order) {
+ return std::atomic_compare_exchange_weak(__p, __v, std::move(__w));
+}
+
+#endif // !defined(_LIBCPP_HAS_NO_THREADS)
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // LLVM_ATOMIC_ATOMIC_SHARED_PTR_H
diff --git a/libcxx/include/__memory/shared_ptr.h b/libcxx/include/__memory/shared_ptr.h
index 9a73d439306d9e..c2a6953382dcd3 100644
--- a/libcxx/include/__memory/shared_ptr.h
+++ b/libcxx/include/__memory/shared_ptr.h
@@ -1556,110 +1556,6 @@ template <class _CharT, class _Traits, class _Yp>
inline _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, shared_ptr<_Yp> const& __p);
-#if !defined(_LIBCPP_HAS_NO_THREADS)
-
-class _LIBCPP_EXPORTED_FROM_ABI __sp_mut {
- void* __lx_;
-
-public:
- void lock() _NOEXCEPT;
- void unlock() _NOEXCEPT;
-
-private:
- _LIBCPP_CONSTEXPR __sp_mut(void*) _NOEXCEPT;
- __sp_mut(const __sp_mut&);
- __sp_mut& operator=(const __sp_mut&);
-
- friend _LIBCPP_EXPORTED_FROM_ABI __sp_mut& __get_sp_mut(const void*);
-};
-
-_LIBCPP_EXPORTED_FROM_ABI __sp_mut& __get_sp_mut(const void*);
-
-template <class _Tp>
-inline _LIBCPP_HIDE_FROM_ABI bool atomic_is_lock_free(const shared_ptr<_Tp>*) {
- return false;
-}
-
-template <class _Tp>
-_LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp> atomic_load(const shared_ptr<_Tp>* __p) {
- __sp_mut& __m = std::__get_sp_mut(__p);
- __m.lock();
- shared_ptr<_Tp> __q = *__p;
- __m.unlock();
- return __q;
-}
-
-template <class _Tp>
-inline _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp> atomic_load_explicit(const shared_ptr<_Tp>* __p, memory_order) {
- return std::atomic_load(__p);
-}
-
-template <class _Tp>
-_LIBCPP_HIDE_FROM_ABI void atomic_store(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r) {
- __sp_mut& __m = std::__get_sp_mut(__p);
- __m.lock();
- __p->swap(__r);
- __m.unlock();
-}
-
-template <class _Tp>
-inline _LIBCPP_HIDE_FROM_ABI void atomic_store_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r, memory_order) {
- std::atomic_store(__p, __r);
-}
-
-template <class _Tp>
-_LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp> atomic_exchange(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r) {
- __sp_mut& __m = std::__get_sp_mut(__p);
- __m.lock();
- __p->swap(__r);
- __m.unlock();
- return __r;
-}
-
-template <class _Tp>
-inline _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp>
-atomic_exchange_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r, memory_order) {
- return std::atomic_exchange(__p, __r);
-}
-
-template <class _Tp>
-_LIBCPP_HIDE_FROM_ABI bool
-atomic_compare_exchange_strong(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w) {
- shared_ptr<_Tp> __temp;
- __sp_mut& __m = std::__get_sp_mut(__p);
- __m.lock();
- if (__p->__owner_equivalent(*__v)) {
- std::swap(__temp, *__p);
- *__p = __w;
- __m.unlock();
- return true;
- }
- std::swap(__temp, *__v);
- *__v = *__p;
- __m.unlock();
- return false;
-}
-
-template <class _Tp>
-inline _LIBCPP_HIDE_FROM_ABI bool
-atomic_compare_exchange_weak(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w) {
- return std::atomic_compare_exchange_strong(__p, __v, __w);
-}
-
-template <class _Tp>
-inline _LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_strong_explicit(
- shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w, memory_order, memory_order) {
- return std::atomic_compare_exchange_strong(__p, __v, __w);
-}
-
-template <class _Tp>
-inline _LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_weak_explicit(
- shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w, memory_order, memory_order) {
- return std::atomic_compare_exchange_weak(__p, __v, __w);
-}
-
-#endif // !defined(_LIBCPP_HAS_NO_THREADS)
-
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___MEMORY_SHARED_PTR_H
diff --git a/libcxx/include/memory b/libcxx/include/memory
index ee245d5fd2dcb2..6c0ec59119f6d2 100644
--- a/libcxx/include/memory
+++ b/libcxx/include/memory
@@ -831,29 +831,29 @@ public:
};
template<class T>
- bool atomic_is_lock_free(const shared_ptr<T>* p);
+ bool atomic_is_lock_free(const shared_ptr<T>* p); // Deprecated in C++20
template<class T>
- shared_ptr<T> atomic_load(const shared_ptr<T>* p);
+ shared_ptr<T> atomic_load(const shared_ptr<T>* p); // Deprecated in C++20
template<class T>
- shared_ptr<T> atomic_load_explicit(const shared_ptr<T>* p, memory_order mo);
+ shared_ptr<T> atomic_load_explicit(const shared_ptr<T>* p, memory_order mo); // Deprecated in C++20
template<class T>
- void atomic_store(shared_ptr<T>* p, shared_ptr<T> r);
+ void atomic_store(shared_ptr<T>* p, shared_ptr<T> r); // Deprecated in C++20
template<class T>
- void atomic_store_explicit(shared_ptr<T>* p, shared_ptr<T> r, memory_order mo);
+ void atomic_store_explicit(shared_ptr<T>* p, shared_ptr<T> r, memory_order mo); // Deprecated in C++20
template<class T>
- shared_ptr<T> atomic_exchange(shared_ptr<T>* p, shared_ptr<T> r);
+ shared_ptr<T> atomic_exchange(shared_ptr<T>* p, shared_ptr<T> r); // Deprecated in C++20
template<class T>
shared_ptr<T>
- atomic_exchange_explicit(shared_ptr<T>* p, shared_ptr<T> r, memory_order mo);
+ atomic_exchange_explicit(shared_ptr<T>* p, shared_ptr<T> r, memory_order mo); // Deprecated in C++20
template<class T>
bool
- atomic_compare_exchange_weak(shared_ptr<T>* p, shared_ptr<T>* v, shared_ptr<T> w);
+ atomic_compare_exchange_weak(shared_ptr<T>* p, shared_ptr<T>* v, shared_ptr<T> w); // Deprecated in C++20
template<class T>
bool
- atomic_compare_exchange_strong( shared_ptr<T>* p, shared_ptr<T>* v, shared_ptr<T> w);
+ atomic_compare_exchange_strong( shared_ptr<T>* p, shared_ptr<T>* v, shared_ptr<T> w); // Deprecated in C++20
template<class T>
bool
- atomic_compare_exchange_weak_explicit(shared_ptr<T>* p, shared_ptr<T>* v,
+ atomic_compare_exchange_weak_explicit(shared_ptr<T>* p, shared_ptr<T>* v, // Deprecated in C++20
shared_ptr<T> w, memory_order success,
memory_order failure);
template<class T>
@@ -912,6 +912,78 @@ void* align(size_t alignment, size_t size, void*& ptr, size_t& space);
template<size_t N, class T>
[[nodiscard]] constexpr T* assume_aligned(T* ptr); // since C++20
+// [util.smartptr.atomic], atomic smart pointers
+template<class T> struct atomic; // since C++20
+template<class T> // since C++20
+struct atomic<shared_ptr<T>>
+{
+ using value_type = shared_ptr<T>;
+
+ static constexpr bool is_always_lock_free = implementation-defined;
+ bool is_lock_free() const noexcept;
+
+ constexpr atomic() noexcept;
+ constexpr atomic(nullptr_t) noexcept : atomic() { }
+ atomic(shared_ptr<T> desired) noexcept;
+ atomic(const atomic&) = delete;
+ void operator=(const atomic&) = delete;
+
+ shared_ptr<T> load(memory_order order = memory_order::seq_cst) const noexcept;
+ operator shared_ptr<T>() const noexcept;
+ void store(shared_ptr<T> desired, memory_order order = memory_order::seq_cst) noexcept;
+ void operator=(shared_ptr<T> desired) noexcept;
+ void operator=(nullptr_t) noexcept;
+
+ shared_ptr<T> exchange(shared_ptr<T> desired,
+ memory_order order = memory_order::seq_cst) noexcept;
+ bool compare_exchange_weak(shared_ptr<T>& expected, shared_ptr<T> desired,
+ memory_order success, memory_order failure) noexcept;
+ bool compare_exchange_strong(shared_ptr<T>& expected, shared_ptr<T> desired,
+ memory_order success, memory_order failure) noexcept;
+ bool compare_exchange_weak(shared_ptr<T>& expected, shared_ptr<T> desired,
+ memory_order order = memory_order::seq_cst) noexcept;
+ bool compare_exchange_strong(shared_ptr<T>& expected, shared_ptr<T> desired,
+ memory_order order = memory_order::seq_cst) noexcept;
+
+ void wait(shared_ptr<T> old, memory_order order = memory_order::seq_cst) const noexcept;
+ void notify_one() noexcept;
+ void notify_all() noexcept;
+};
+template<class T> // since C++20
+struct atomic<weak_ptr<T>>
+{
+
+ using value_type = weak_ptr<T>;
+
+ static constexpr bool is_always_lock_free = implementation-defined;
+ bool is_lock_free() const noexcept;
+
+ constexpr atomic() noexcept;
+ atomic(weak_ptr<T> desired) noexcept;
+ atomic(const atomic&) = delete;
+ void operator=(const atomic&) = delete;
+
+ weak_ptr<T> load(memory_order order = memory_order::seq_cst) const noexcept;
+ operator weak_ptr<T>() const noexcept;
+ void store(weak_ptr<T> desired, memory_order order = memory_order::seq_cst) noexcept;
+ void operator=(weak_ptr<T> desired) noexcept;
+
+ weak_ptr<T> exchange(weak_ptr<T> desired,
+ memory_order order = memory_order::seq_cst) noexcept;
+ bool compare_exchange_weak(weak_ptr<T>& expected, weak_ptr<T> desired,
+ memory_order success, memory_order failure) noexcept;
+ bool compare_exchange_strong(weak_ptr<T>& expected, weak_ptr<T> desired,
+ memory_order success, memory_order failure) noexcept;
+ bool compare_exchange_weak(weak_ptr<T>& expected, weak_ptr<T> desired,
+ memory_order order = memory_order::seq_cst) noexcept;
+ bool compare_exchange_strong(weak_ptr<T>& expected, weak_ptr<T> desired,
+ memory_order order = memory_order::seq_cst) noexcept;
+
+ void wait(weak_ptr<T> old, memory_order order = memory_order::seq_cst) const noexcept;
+ void notify_one() noexcept;
+ void notify_all() noexcept;
+};
+
} // std
*/
@@ -928,6 +1000,7 @@ template<size_t N, class T>
#include <__memory/allocator_arg_t.h>
#include <__memory/allocator_traits.h>
#include <__memory/assume_aligned.h>
+#include <__memory/atomic_shared_ptr.h>
#include <__memory/auto_ptr.h>
#include <__memory/compressed_pair.h>
#include <__memory/concepts.h>
diff --git a/libcxx/include/module.modulemap.in b/libcxx/include/module.modulemap.in
index d10670d4faaffc..dd65019e292e26 100644
--- a/libcxx/include/module.modulemap.in
+++ b/libcxx/include/module.modulemap.in
@@ -1508,6 +1508,7 @@ module std_private_memory_allocator_arg_t [system] { header "__m
module std_private_memory_allocator_destructor [system] { header "__memory/allocator_destructor.h" }
module std_private_memory_allocator_traits [system] { header "__memory/allocator_traits.h" }
module std_private_memory_assume_aligned [system] { header "__memory/assume_aligned.h" }
+module std_private_memory_atomic_shared_ptr [system] { header "__memory/atomic_shared_ptr.h" }
module std_private_memory_auto_ptr [system] { header "__memory/auto_ptr.h" }
module std_private_memory_builtin_new_allocator [system] {
header "__memory/builtin_new_allocator.h"
diff --git a/libcxx/include/version b/libcxx/include/version
index c96647894dce63..2a0d8b6db626e0 100644
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -348,7 +348,7 @@ __cpp_lib_within_lifetime 202306L <type_traits>
// # define __cpp_lib_atomic_float 201711L
# define __cpp_lib_atomic_lock_free_type_aliases 201907L
// # define __cpp_lib_atomic_ref 201806L
-// # define __cpp_lib_atomic_shared_ptr 201711L
+# define __cpp_lib_atomic_shared_ptr 201711L
# define __cpp_lib_atomic_value_initialization 201911L
# if _LIBCPP_AVAILABILITY_HAS_SYNC
# define __cpp_lib_atomic_wait 201907L
diff --git a/libcxx/modules/std/memory.inc b/libcxx/modules/std/memory.inc
index fba2461732c1b9..9263bbf0cc49e1 100644
--- a/libcxx/modules/std/memory.inc
+++ b/libcxx/modules/std/memory.inc
@@ -190,6 +190,9 @@ export namespace std {
// using std::inout_ptr;
#ifndef _LIBCPP_HAS_NO_THREADS
+ // [util.smartptr.atomic]
+ using std::atomic;
+
// [depr.util.smartptr.shared.atomic]
using std::atomic_is_lock_free;
diff --git a/libcxx/test/std/atomics/types.pass.cpp b/libcxx/test/std/atomics/types.pass.cpp
index cebf66ee7f1af0..4fb62d9d13caab 100644
--- a/libcxx/test/std/atomics/types.pass.cpp
+++ b/libcxx/test/std/atomics/types.pass.cpp
@@ -181,9 +181,8 @@ int main(int, char**)
test<std::atomic_unsigned_lock_free::value_type>();
static_assert(std::is_unsigned_v<std::atomic_unsigned_lock_free::value_type>);
static_assert(std::is_integral_v<std::atomic_unsigned_lock_free::value_type>);
-/*
test<std::shared_ptr<int>>();
-*/
+ test<std::weak_ptr<int>>();
#endif
return 0;
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/atomic.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/atomic.version.compile.pass.cpp
index 86315c23a496bf..346d31304cd358 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/atomic.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/atomic.version.compile.pass.cpp
@@ -196,17 +196,11 @@
# endif
# endif
-# if !defined(_LIBCPP_VERSION)
-# ifndef __cpp_lib_atomic_shared_ptr
-# error "__cpp_lib_atomic_shared_ptr should be defined in c++20"
-# endif
-# if __cpp_lib_atomic_shared_ptr != 201711L
-# error "__cpp_lib_atomic_shared_ptr should have the value 201711L in c++20"
-# endif
-# else // _LIBCPP_VERSION
-# ifdef __cpp_lib_atomic_shared_ptr
-# error "__cpp_lib_atomic_shared_ptr should not be defined because it is unimplemented in libc++!"
-# endif
+# ifndef __cpp_lib_atomic_shared_ptr
+# error "__cpp_lib_atomic_shared_ptr should be defined in c++20"
+# endif
+# if __cpp_lib_atomic_shared_ptr != 201711L
+# error "__cpp_lib_atomic_shared_ptr should have the value 201711L in c++20"
# endif
# ifndef __cpp_lib_atomic_value_initialization
@@ -291,17 +285,11 @@
# endif
# endif
-# if !defined(_LIBCPP_VERSION)
-# ifndef __cpp_lib_atomic_shared_ptr
-# error "__cpp_lib_atomic_shared_ptr should be defined in c++23"
-# endif
-# if __cpp_lib_atomic_shared_ptr != 201711L
-# error "__cpp_lib_atomic_shared_ptr should have the value 201711L in c++23"
-# endif
-# else // _LIBCPP_VERSION
-# ifdef __cpp_lib_atomic_shared_ptr
-# error "__cpp_lib_atomic_shared_ptr should not be defined because it is unimplemented in libc++!"
-# endif
+# ifndef __cpp_lib_atomic_shared_ptr
+# error "__cpp_lib_atomic_shared_ptr should be defined in c++23"
+# endif
+# if __cpp_lib_atomic_shared_ptr != 201711L
+# error "__cpp_lib_atomic_shared_ptr should have the value 201711L in c++23"
# endif
# ifndef __cpp_lib_atomic_value_initialization
@@ -386,17 +374,11 @@
# endif
# endif
-# if !defined(_LIBCPP_VERSION)
-# ifndef __cpp_lib_atomic_shared_ptr
-# error "__cpp_lib_atomic_shared_ptr should be defined in c++26"
-# endif
-# if __cpp_lib_atomic_shared_ptr != 201711L
-# error "__cpp_lib_atomic_shared_ptr should have the value 201711L in c++26"
-# endif
-# else // _LIBCPP_VERSION
-# ifdef __cpp_lib_atomic_shared_ptr
-# error "__cpp_lib_atomic_shared_ptr should not be defined because it is unimplemented in libc++!"
-# endif
+# ifndef __cpp_lib_atomic_shared_ptr
+# error "__cpp_lib_atomic_shared_ptr should be defined in c++26"
+# endif
+# if __cpp_lib_atomic_shared_ptr != 201711L
+# error "__cpp_lib_atomic_shared_ptr should have the value 201711L in c++26"
# endif
# ifndef __cpp_lib_atomic_value_initialization
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
index d5a0839b30f824..acc30418fbb77c 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
@@ -3038,17 +3038,11 @@
# endif
# endif
-# if !defined(_LIBCPP_VERSION)
-# ifndef __cpp_lib_atomic_shared_ptr
-# error "__cpp_lib_atomic_shared_ptr should be defined in c++20"
-# endif
-# if __cpp_lib_atomic_shared_ptr != 201711L
-# error "__cpp_lib_atomic_shared_ptr should have the value 201711L in c++20"
-# endif
-# else // _LIBCPP_VERSION
-# ifdef __cpp_lib_atomic_shared_ptr
-# error "__cpp_lib_atomic_shared_ptr should not be defined because it is unimplemented in libc++!"
-# endif
+# ifndef __cpp_lib_atomic_shared_ptr
+# error "__cpp_lib_atomic_shared_ptr should be defined in c++20"
+# endif
+# if __cpp_lib_atomic_shared_ptr != 201711L
+# error "__cpp_lib_atomic_shared_ptr should have the value 201711L in c++20"
# endif
# ifndef __cpp_lib_atomic_value_initialization
@@ -4389,17 +4383,11 @@
# endif
# endif
-# if !defined(_LIBCPP_VERSION)
-# ifndef __cpp_lib_atomic_shared_ptr
-# error "__cpp_lib_atomic_shared_ptr should be defined in c++23"
-# endif
-# if __cpp_lib_atomic_shared_ptr != 201711L
-# error "__cpp_lib_atomic_shared_ptr should have the value 201711L in c++23"
-# endif
-# else // _LIBCPP_VERSION
-# ifdef __cpp_lib_atomic_shared_ptr
-# error "__cpp_lib_atomic_shared_ptr should not be defined because it is unimplemented in libc++!"
-# endif
+# ifndef __cpp_lib_atomic_shared_ptr
+# error "__cpp_lib_atomic_shared_ptr should be defined in c++23"
+# endif
+# if __cpp_lib_atomic_shared_ptr != 201711L
+# error "__cpp_lib_atomic_shared_ptr should have the value 201711L in c++23"
# endif
# ifndef __cpp_lib_atomic_value_initialization
@@ -5965,17 +5953,11 @@
# endif
# endif
-# if !defined(_LIBCPP_VERSION)
-# ifndef __cpp_lib_atomic_shared_ptr
-# error "__cpp_lib_atomic_shared_ptr should be defined in c++26"
-# endif
-# if __cpp_lib_atomic_shared_ptr != 201711L
-# error "__cpp_lib_atomic_shared_ptr should have the value 201711L in c++26"
-# endif
-# else // _LIBCPP_VERSION
-# ifdef __cpp_lib_atomic_shared_ptr
-# error "__cpp_lib_atomic_shared_ptr should not be defined because it is unimplemented in libc++!"
-# endif
+# ifndef __cpp_lib_atomic_shared_ptr
+# error "__cpp_lib_atomic_shared_ptr should be defined in c++26"
+# endif
+# if __cpp_lib_atomic_shared_ptr != 201711L
+# error "__cpp_lib_atomic_shared_ptr should have the value 201711L in c++26"
# endif
# ifndef __cpp_lib_atomic_value_initialization
diff --git a/libcxx/utils/generate_feature_test_macro_components.py b/libcxx/utils/generate_feature_test_macro_components.py
index 8ee92909dfa53c..d32d976fbc4a65 100755
--- a/libcxx/utils/generate_feature_test_macro_components.py
+++ b/libcxx/utils/generate_feature_test_macro_components.py
@@ -181,7 +181,6 @@ def add_version_header(tc):
"name": "__cpp_lib_atomic_shared_ptr",
"values": {"c++20": 201711},
"headers": ["atomic"],
- "unimplemented": True,
},
{
"name": "__cpp_lib_atomic_value_initialization",
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