[libcxx-commits] [libcxx] [libc++] constexpr atomic and atomic_ref (PR #98765)

via libcxx-commits libcxx-commits at lists.llvm.org
Sat Jul 13 12:30:47 PDT 2024


Hana =?utf-8?q?Dusíková?= <hanicka at hanicka.net>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/98765 at github.com>


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libcxx

Author: Hana Dusíková (hanickadot)

<details>
<summary>Changes</summary>

This is implementation of constexpr `atomic<T>` and `atomic_ref<T>`. This PR depends on https://github.com/llvm/llvm-project/pull/98756

It's missing library tests (language PR contains tests) which will be added.

I'm not sure how is the proper way to make the constexpr support conditional, for now it's allowed in c++26 mode only.

---

Patch is 79.49 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/98765.diff


7 Files Affected:

- (modified) libcxx/include/__atomic/atomic.h (+52-43) 
- (modified) libcxx/include/__atomic/atomic_base.h (+46-30) 
- (modified) libcxx/include/__atomic/atomic_flag.h (+37-23) 
- (modified) libcxx/include/__atomic/atomic_ref.h (+214-100) 
- (modified) libcxx/include/__atomic/cxx_atomic_impl.h (+42-35) 
- (modified) libcxx/include/__config (+6) 
- (modified) libcxx/include/version (+3) 


``````````diff
diff --git a/libcxx/include/__atomic/atomic.h b/libcxx/include/__atomic/atomic.h
index bd3f659c22df0..4a72f61d019fc 100644
--- a/libcxx/include/__atomic/atomic.h
+++ b/libcxx/include/__atomic/atomic.h
@@ -67,7 +67,7 @@ struct atomic<_Tp*> : public __atomic_base<_Tp*> {
   using value_type      = _Tp*;
   using difference_type = ptrdiff_t;
 
-  _LIBCPP_HIDE_FROM_ABI atomic() _NOEXCEPT = default;
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 atomic() _NOEXCEPT = default;
 
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR atomic(_Tp* __d) _NOEXCEPT : __base(__d) {}
 
@@ -75,7 +75,7 @@ struct atomic<_Tp*> : public __atomic_base<_Tp*> {
     __base::store(__d);
     return __d;
   }
-  _LIBCPP_HIDE_FROM_ABI _Tp* operator=(_Tp* __d) _NOEXCEPT {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp* operator=(_Tp* __d) _NOEXCEPT {
     __base::store(__d);
     return __d;
   }
@@ -86,7 +86,8 @@ struct atomic<_Tp*> : public __atomic_base<_Tp*> {
     return std::__cxx_atomic_fetch_add(std::addressof(this->__a_), __op, __m);
   }
 
-  _LIBCPP_HIDE_FROM_ABI _Tp* fetch_add(ptrdiff_t __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp*
+  fetch_add(ptrdiff_t __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
     // __atomic_fetch_add accepts function pointers, guard against them.
     static_assert(!is_function<__remove_pointer_t<_Tp> >::value, "Pointer to function isn't allowed");
     return std::__cxx_atomic_fetch_add(std::addressof(this->__a_), __op, __m);
@@ -98,24 +99,25 @@ struct atomic<_Tp*> : public __atomic_base<_Tp*> {
     return std::__cxx_atomic_fetch_sub(std::addressof(this->__a_), __op, __m);
   }
 
-  _LIBCPP_HIDE_FROM_ABI _Tp* fetch_sub(ptrdiff_t __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp*
+  fetch_sub(ptrdiff_t __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
     // __atomic_fetch_add accepts function pointers, guard against them.
     static_assert(!is_function<__remove_pointer_t<_Tp> >::value, "Pointer to function isn't allowed");
     return std::__cxx_atomic_fetch_sub(std::addressof(this->__a_), __op, __m);
   }
 
   _LIBCPP_HIDE_FROM_ABI _Tp* operator++(int) volatile _NOEXCEPT { return fetch_add(1); }
-  _LIBCPP_HIDE_FROM_ABI _Tp* operator++(int) _NOEXCEPT { return fetch_add(1); }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp* operator++(int) _NOEXCEPT { return fetch_add(1); }
   _LIBCPP_HIDE_FROM_ABI _Tp* operator--(int) volatile _NOEXCEPT { return fetch_sub(1); }
-  _LIBCPP_HIDE_FROM_ABI _Tp* operator--(int) _NOEXCEPT { return fetch_sub(1); }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp* operator--(int) _NOEXCEPT { return fetch_sub(1); }
   _LIBCPP_HIDE_FROM_ABI _Tp* operator++() volatile _NOEXCEPT { return fetch_add(1) + 1; }
-  _LIBCPP_HIDE_FROM_ABI _Tp* operator++() _NOEXCEPT { return fetch_add(1) + 1; }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp* operator++() _NOEXCEPT { return fetch_add(1) + 1; }
   _LIBCPP_HIDE_FROM_ABI _Tp* operator--() volatile _NOEXCEPT { return fetch_sub(1) - 1; }
-  _LIBCPP_HIDE_FROM_ABI _Tp* operator--() _NOEXCEPT { return fetch_sub(1) - 1; }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp* operator--() _NOEXCEPT { return fetch_sub(1) - 1; }
   _LIBCPP_HIDE_FROM_ABI _Tp* operator+=(ptrdiff_t __op) volatile _NOEXCEPT { return fetch_add(__op) + __op; }
-  _LIBCPP_HIDE_FROM_ABI _Tp* operator+=(ptrdiff_t __op) _NOEXCEPT { return fetch_add(__op) + __op; }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp* operator+=(ptrdiff_t __op) _NOEXCEPT { return fetch_add(__op) + __op; }
   _LIBCPP_HIDE_FROM_ABI _Tp* operator-=(ptrdiff_t __op) volatile _NOEXCEPT { return fetch_sub(__op) - __op; }
-  _LIBCPP_HIDE_FROM_ABI _Tp* operator-=(ptrdiff_t __op) _NOEXCEPT { return fetch_sub(__op) - __op; }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp* operator-=(ptrdiff_t __op) _NOEXCEPT { return fetch_sub(__op) - __op; }
 
   atomic& operator=(const atomic&)          = delete;
   atomic& operator=(const atomic&) volatile = delete;
@@ -151,7 +153,7 @@ struct atomic<_Tp> : __atomic_base<_Tp> {
   }
 
   template <class _This, class _Operation, class _BuiltinOp>
-  _LIBCPP_HIDE_FROM_ABI static _Tp
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 static _Tp
   __rmw_op(_This&& __self, _Tp __operand, memory_order __m, _Operation __operation, _BuiltinOp __builtin_op) {
     if constexpr (__has_rmw_builtin()) {
       return __builtin_op(std::addressof(std::forward<_This>(__self).__a_), __operand, __m);
@@ -174,7 +176,7 @@ struct atomic<_Tp> : __atomic_base<_Tp> {
   }
 
   template <class _This>
-  _LIBCPP_HIDE_FROM_ABI static _Tp __fetch_add(_This&& __self, _Tp __operand, memory_order __m) {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 static _Tp __fetch_add(_This&& __self, _Tp __operand, memory_order __m) {
     auto __builtin_op = [](auto __a, auto __builtin_operand, auto __order) {
       return std::__cxx_atomic_fetch_add(__a, __builtin_operand, __order);
     };
@@ -182,7 +184,7 @@ struct atomic<_Tp> : __atomic_base<_Tp> {
   }
 
   template <class _This>
-  _LIBCPP_HIDE_FROM_ABI static _Tp __fetch_sub(_This&& __self, _Tp __operand, memory_order __m) {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 static _Tp __fetch_sub(_This&& __self, _Tp __operand, memory_order __m) {
     auto __builtin_op = [](auto __a, auto __builtin_operand, auto __order) {
       return std::__cxx_atomic_fetch_sub(__a, __builtin_operand, __order);
     };
@@ -207,7 +209,7 @@ struct atomic<_Tp> : __atomic_base<_Tp> {
     __base::store(__d);
     return __d;
   }
-  _LIBCPP_HIDE_FROM_ABI _Tp operator=(_Tp __d) noexcept {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp operator=(_Tp __d) noexcept {
     __base::store(__d);
     return __d;
   }
@@ -218,7 +220,7 @@ struct atomic<_Tp> : __atomic_base<_Tp> {
     return __fetch_add(*this, __op, __m);
   }
 
-  _LIBCPP_HIDE_FROM_ABI _Tp fetch_add(_Tp __op, memory_order __m = memory_order_seq_cst) noexcept {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp fetch_add(_Tp __op, memory_order __m = memory_order_seq_cst) noexcept {
     return __fetch_add(*this, __op, __m);
   }
 
@@ -228,7 +230,7 @@ struct atomic<_Tp> : __atomic_base<_Tp> {
     return __fetch_sub(*this, __op, __m);
   }
 
-  _LIBCPP_HIDE_FROM_ABI _Tp fetch_sub(_Tp __op, memory_order __m = memory_order_seq_cst) noexcept {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp fetch_sub(_Tp __op, memory_order __m = memory_order_seq_cst) noexcept {
     return __fetch_sub(*this, __op, __m);
   }
 
@@ -238,7 +240,7 @@ struct atomic<_Tp> : __atomic_base<_Tp> {
     return fetch_add(__op) + __op;
   }
 
-  _LIBCPP_HIDE_FROM_ABI _Tp operator+=(_Tp __op) noexcept { return fetch_add(__op) + __op; }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp operator+=(_Tp __op) noexcept { return fetch_add(__op) + __op; }
 
   _LIBCPP_HIDE_FROM_ABI _Tp operator-=(_Tp __op) volatile noexcept
     requires __base::is_always_lock_free
@@ -246,7 +248,7 @@ struct atomic<_Tp> : __atomic_base<_Tp> {
     return fetch_sub(__op) - __op;
   }
 
-  _LIBCPP_HIDE_FROM_ABI _Tp operator-=(_Tp __op) noexcept { return fetch_sub(__op) - __op; }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp operator-=(_Tp __op) noexcept { return fetch_sub(__op) - __op; }
 };
 
 #endif // _LIBCPP_STD_VER >= 20
@@ -272,7 +274,7 @@ atomic_init(volatile atomic<_Tp>* __o, typename atomic<_Tp>::value_type __d) _NO
 }
 
 template <class _Tp>
-_LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI void
+_LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI void
 atomic_init(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __d) _NOEXCEPT {
   std::__cxx_atomic_init(std::addressof(__o->__a_), __d);
 }
@@ -285,7 +287,8 @@ _LIBCPP_HIDE_FROM_ABI void atomic_store(volatile atomic<_Tp>* __o, typename atom
 }
 
 template <class _Tp>
-_LIBCPP_HIDE_FROM_ABI void atomic_store(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __d) _NOEXCEPT {
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void
+atomic_store(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __d) _NOEXCEPT {
   __o->store(__d);
 }
 
@@ -299,7 +302,7 @@ atomic_store_explicit(volatile atomic<_Tp>* __o, typename atomic<_Tp>::value_typ
 }
 
 template <class _Tp>
-_LIBCPP_HIDE_FROM_ABI void
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void
 atomic_store_explicit(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __d, memory_order __m) _NOEXCEPT
     _LIBCPP_CHECK_STORE_MEMORY_ORDER(__m) {
   __o->store(__d, __m);
@@ -313,7 +316,7 @@ _LIBCPP_HIDE_FROM_ABI _Tp atomic_load(const volatile atomic<_Tp>* __o) _NOEXCEPT
 }
 
 template <class _Tp>
-_LIBCPP_HIDE_FROM_ABI _Tp atomic_load(const atomic<_Tp>* __o) _NOEXCEPT {
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp atomic_load(const atomic<_Tp>* __o) _NOEXCEPT {
   return __o->load();
 }
 
@@ -326,7 +329,7 @@ _LIBCPP_HIDE_FROM_ABI _Tp atomic_load_explicit(const volatile atomic<_Tp>* __o,
 }
 
 template <class _Tp>
-_LIBCPP_HIDE_FROM_ABI _Tp atomic_load_explicit(const atomic<_Tp>* __o, memory_order __m) _NOEXCEPT
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp atomic_load_explicit(const atomic<_Tp>* __o, memory_order __m) _NOEXCEPT
     _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m) {
   return __o->load(__m);
 }
@@ -339,7 +342,8 @@ _LIBCPP_HIDE_FROM_ABI _Tp atomic_exchange(volatile atomic<_Tp>* __o, typename at
 }
 
 template <class _Tp>
-_LIBCPP_HIDE_FROM_ABI _Tp atomic_exchange(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __d) _NOEXCEPT {
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp
+atomic_exchange(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __d) _NOEXCEPT {
   return __o->exchange(__d);
 }
 
@@ -352,7 +356,7 @@ atomic_exchange_explicit(volatile atomic<_Tp>* __o, typename atomic<_Tp>::value_
 }
 
 template <class _Tp>
-_LIBCPP_HIDE_FROM_ABI _Tp
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp
 atomic_exchange_explicit(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __d, memory_order __m) _NOEXCEPT {
   return __o->exchange(__d, __m);
 }
@@ -366,7 +370,7 @@ _LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_weak(
 }
 
 template <class _Tp>
-_LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_weak(
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 bool atomic_compare_exchange_weak(
     atomic<_Tp>* __o, typename atomic<_Tp>::value_type* __e, typename atomic<_Tp>::value_type __d) _NOEXCEPT {
   return __o->compare_exchange_weak(*__e, __d);
 }
@@ -380,7 +384,7 @@ _LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_strong(
 }
 
 template <class _Tp>
-_LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_strong(
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 bool atomic_compare_exchange_strong(
     atomic<_Tp>* __o, typename atomic<_Tp>::value_type* __e, typename atomic<_Tp>::value_type __d) _NOEXCEPT {
   return __o->compare_exchange_strong(*__e, __d);
 }
@@ -398,7 +402,7 @@ _LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_weak_explicit(
 }
 
 template <class _Tp>
-_LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_weak_explicit(
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 bool atomic_compare_exchange_weak_explicit(
     atomic<_Tp>* __o,
     typename atomic<_Tp>::value_type* __e,
     typename atomic<_Tp>::value_type __d,
@@ -420,7 +424,7 @@ _LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_strong_explicit(
 }
 
 template <class _Tp>
-_LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_strong_explicit(
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 bool atomic_compare_exchange_strong_explicit(
     atomic<_Tp>* __o,
     typename atomic<_Tp>::value_type* __e,
     typename atomic<_Tp>::value_type __d,
@@ -438,7 +442,7 @@ atomic_wait(const volatile atomic<_Tp>* __o, typename atomic<_Tp>::value_type __
 }
 
 template <class _Tp>
-_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void
+_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void
 atomic_wait(const atomic<_Tp>* __o, typename atomic<_Tp>::value_type __v) _NOEXCEPT {
   return __o->wait(__v);
 }
@@ -453,7 +457,7 @@ atomic_wait_explicit(const volatile atomic<_Tp>* __o, typename atomic<_Tp>::valu
 }
 
 template <class _Tp>
-_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void
+_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void
 atomic_wait_explicit(const atomic<_Tp>* __o, typename atomic<_Tp>::value_type __v, memory_order __m) _NOEXCEPT
     _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m) {
   return __o->wait(__v, __m);
@@ -467,7 +471,7 @@ atomic_notify_one(volatile atomic<_Tp>* __o) _NOEXCEPT {
   __o->notify_one();
 }
 template <class _Tp>
-_LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void
+_LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void
 atomic_notify_one(atomic<_Tp>* __o) _NOEXCEPT {
   __o->notify_one();
 }
@@ -480,7 +484,7 @@ atomic_notify_all(volatile atomic<_Tp>* __o) _NOEXCEPT {
   __o->notify_all();
 }
 template <class _Tp>
-_LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void
+_LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void
 atomic_notify_all(atomic<_Tp>* __o) _NOEXCEPT {
   __o->notify_all();
 }
@@ -494,7 +498,8 @@ atomic_fetch_add(volatile atomic<_Tp>* __o, typename atomic<_Tp>::difference_typ
 }
 
 template <class _Tp>
-_LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_add(atomic<_Tp>* __o, typename atomic<_Tp>::difference_type __op) _NOEXCEPT {
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp
+atomic_fetch_add(atomic<_Tp>* __o, typename atomic<_Tp>::difference_type __op) _NOEXCEPT {
   return __o->fetch_add(__op);
 }
 
@@ -507,7 +512,7 @@ _LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_add_explicit(
 }
 
 template <class _Tp>
-_LIBCPP_HIDE_FROM_ABI _Tp
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp
 atomic_fetch_add_explicit(atomic<_Tp>* __o, typename atomic<_Tp>::difference_type __op, memory_order __m) _NOEXCEPT {
   return __o->fetch_add(__op, __m);
 }
@@ -521,7 +526,8 @@ atomic_fetch_sub(volatile atomic<_Tp>* __o, typename atomic<_Tp>::difference_typ
 }
 
 template <class _Tp>
-_LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_sub(atomic<_Tp>* __o, typename atomic<_Tp>::difference_type __op) _NOEXCEPT {
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp
+atomic_fetch_sub(atomic<_Tp>* __o, typename atomic<_Tp>::difference_type __op) _NOEXCEPT {
   return __o->fetch_sub(__op);
 }
 
@@ -534,7 +540,7 @@ _LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_sub_explicit(
 }
 
 template <class _Tp>
-_LIBCPP_HIDE_FROM_ABI _Tp
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp
 atomic_fetch_sub_explicit(atomic<_Tp>* __o, typename atomic<_Tp>::difference_type __op, memory_order __m) _NOEXCEPT {
   return __o->fetch_sub(__op, __m);
 }
@@ -547,7 +553,8 @@ _LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_and(volatile atomic<_Tp>* __o, typename a
 }
 
 template <class _Tp, __enable_if_t<is_integral<_Tp>::value && !is_same<_Tp, bool>::value, int> = 0>
-_LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_and(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op) _NOEXCEPT {
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp
+atomic_fetch_and(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op) _NOEXCEPT {
   return __o->fetch_and(__op);
 }
 
@@ -560,7 +567,7 @@ _LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_and_explicit(
 }
 
 template <class _Tp, __enable_if_t<is_integral<_Tp>::value && !is_same<_Tp, bool>::value, int> = 0>
-_LIBCPP_HIDE_FROM_ABI _Tp
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp
 atomic_fetch_and_explicit(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op, memory_order __m) _NOEXCEPT {
   return __o->fetch_and(__op, __m);
 }
@@ -573,7 +580,8 @@ _LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_or(volatile atomic<_Tp>* __o, typename at
 }
 
 template <class _Tp, __enable_if_t<is_integral<_Tp>::value && !is_same<_Tp, bool>::value, int> = 0>
-_LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_or(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op) _NOEXCEPT {
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp
+atomic_fetch_or(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op) _NOEXCEPT {
   return __o->fetch_or(__op);
 }
 
@@ -586,7 +594,7 @@ atomic_fetch_or_explicit(volatile atomic<_Tp>* __o, typename atomic<_Tp>::value_
 }
 
 template <class _Tp, __enable_if_t<is_integral<_Tp>::value && !is_same<_Tp, bool>::value, int> = 0>
-_LIBCPP_HIDE_FROM_ABI _Tp
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp
 atomic_fetch_or_explicit(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op, memory_order __m) _NOEXCEPT {
   return __o->fetch_or(__op, __m);
 }
@@ -599,7 +607,8 @@ _LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_xor(volatile atomic<_Tp>* __o, typename a
 }
 
 template <class _Tp, __enable_if_t<is_integral<_Tp>::value && !is_same<_Tp, bool>::value, int> = 0>
-_LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_xor(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op) _NOEXCEPT {
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp
+atomic_fetch_xor(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op) _NOEXCEPT {
   return __o->fetch_xor(__op);
 }
 
@@ -612,7 +621,7 @@ _LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_xor_explicit(
 }
 
 template <class _Tp, __enable_if_t<is_integral<_Tp>::value && !is_same<_Tp, bool>::value, int> = 0>
-_LIBCPP_HIDE_FROM_ABI _Tp
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp
 atomic_fetch_xor_explicit(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op, memory_order __m) _NOEXCEPT {
   return __o->fetch_xor(__op, __m);
 }
diff --git a/libcxx/include/__atomic/atomic_base.h b/libcxx/include/__atomic/atomic_base.h
index 7e26434c9c3a0..22e898f736674 100644
--- a/libcxx/include/__atomic/atomic_base.h
+++ b/libcxx/include/__atomic/atomic_base.h
@@ -40,13 +40,13 @@ struct __atomic_base // false
     return __cxx_atomic_is_lock_free(sizeof(__cxx_atomic_impl<_Tp>));
   }
   _LIBCPP_HIDE_FROM_ABI bool is_lock_free() const _NOEXCEPT {
-    return static_cast<__atomic_base const volatile*>(this)->is_lock_free();
+    return __cxx_atomic_is_lock_free(sizeof(__cxx_atomic_impl<_Tp>));
   }
   _LIBCPP_HIDE_FROM_ABI void store(_Tp __d, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
       _LIBCPP_CHECK_STORE_MEMORY_ORDER(__m) {
     std::__cxx_atomic_store(std::addressof(__a_), __d, __m);
   }
-  _LIBCPP_HIDE_FROM_ABI void store(_Tp __d, memory_order __m = memory_order_seq_cst) _NOEXCEPT
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void store(_Tp __d, memory_order __m = memory_order_seq_cst) _NOEXCEPT
       _LIBCPP_CHECK_STORE_MEMORY_ORDER(__m) {
     std::__cxx_atomic_store(std::addressof(__a_), __d, __m);
   }
@@ -54,16 +54,16 @@ struct __atomic_base // false
       _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m) {
     return std::__cxx_atomic_load(std::addressof(__a_), __m);
   }
-  _LIBCPP_HIDE_FROM_ABI _Tp load(memory_order __m = memory_order_seq_cst) const _NOEXCEPT
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp load(memory_order __m = memory_order_seq_cst) const _NOEXCEPT
       _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m) {
     return std::__cxx_atomic_load(std::addressof(__a_), __m);
   }
   _LIBCPP_HIDE_FROM_ABI operator _Tp() const volatile _NOEXCEPT { return load(); }
-  _LIBCPP_HIDE_FROM_ABI operator _Tp() const _NOEXCEPT { return load(); }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 operator _Tp() const _NOEXCEPT { return load(); }
   _LIBCPP_HIDE_FROM_ABI _Tp exchange(_Tp __d, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT {
     return std::__cxx_atomic_exchange(std::addressof(__a_), __d, __m);
   }
-  _LIBCPP_HIDE_FROM_ABI _Tp exchange(_Tp __d, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp exchange(_Tp __d, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
     return std::__cxx_atomic_exchange(std::addressof(__a_), __d, __m);
   }
   _LIBCPP_HIDE_FROM_ABI bool
@@ -71,7 +71,8 @@ struct __atomic_base // false
       _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f) {
     return std::__cxx_atomic_compare_exchange_weak(std::addressof(__a_), std::addressof(__e), __d, __s, __f);
   }
-  _LIBCPP_HIDE_FROM_ABI bool compa...
[truncated]

``````````

</details>


https://github.com/llvm/llvm-project/pull/98765


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