libstdc++: make atomic waiting depend on gthreads or futexes

libstdc++-v3/ChangeLog:

	* include/bits/atomic_wait.h: Do not define anything unless
	gthreads or futexes are available.
	* include/bits/atomic_timed_wait.h: Likewise.
	* include/bits/semaphore_base.h: Likewise.
	* include/std/semaphore: Likewise.
	* include/bits/atomic_base.h (atomic_flag::wait)
	(atomic_flag::notify_one, atomic_flag::notify_all)
	(__atomic_base<I>::wait, __atomic_base<I>::notify_one)
	(__atomic_base<I>::notify_all, __atomic_base<P*>::wait)
	(__atomic_base<P*>::notify_one, __atomic_base<P*>::notify_all)
	(__atomic_impl::wait, __atomic_impl::notify_one)
	(__atomic_impl::notify_all, __atomic_float::wait)
	(__atomic_float::notify_one, __atomic_float::notify_all)
	(__atomic_ref::wait, __atomic_ref::notify_one)
	(__atomic_ref::notify_all): Only define if gthreads or futexes
	are available.
	* include/std/atomic (atomic::wait, atomic::notify_one)
	(atomic::notify_all): Likewise.
	* include/std/version (__cpp_lib_semaphore): Define
	conditionally.

diff --git a/libstdc++-v3/include/bits/atomic_base.h b/libstdc++-v3/include/bits/atomic_base.h
index 7de02f1..d7db861 100644 (file)
--- a/libstdc++-v3/include/bits/atomic_base.h
+++ b/libstdc++-v3/include/bits/atomic_base.h
@@ -230,6 +230,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       return __v == __GCC_ATOMIC_TEST_AND_SET_TRUEVAL;
     }
 
+#if defined _GLIBCXX_HAS_GTHREADS || _GLIBCXX_HAVE_LINUX_FUTEX
     _GLIBCXX_ALWAYS_INLINE void
     wait(bool __old,
        memory_order __m = memory_order_seq_cst) const noexcept
@@ -252,6 +253,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     { std::__atomic_notify(&_M_i, true); }
 
     // TODO add const volatile overload
+#endif // GTHREADS || LINUX_FUTEX
 #endif // C++20
 
     _GLIBCXX_ALWAYS_INLINE void
@@ -603,6 +605,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       }
 
 #if __cplusplus > 201703L
+#if defined _GLIBCXX_HAS_GTHREADS || _GLIBCXX_HAVE_LINUX_FUTEX
       _GLIBCXX_ALWAYS_INLINE void
       wait(__int_type __old,
          memory_order __m = memory_order_seq_cst) const noexcept
@@ -625,6 +628,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       { std::__atomic_notify(&_M_i, true); }
 
       // TODO add const volatile overload
+#endif // GTHREADS || LINUX_FUTEX
 #endif // C++2a
 
       _GLIBCXX_ALWAYS_INLINE __int_type
@@ -897,6 +901,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       }
 
 #if __cplusplus > 201703L
+#if defined _GLIBCXX_HAS_GTHREADS || _GLIBCXX_HAVE_LINUX_FUTEX
       _GLIBCXX_ALWAYS_INLINE void
       wait(__pointer_type __old,
           memory_order __m = memory_order_seq_cst) noexcept
@@ -919,6 +924,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       { std::__atomic_notify(&_M_p, true); }
 
       // TODO add const volatile overload
+#endif // GTHREADS || LINUX_FUTEX
 #endif // C++2a
 
       _GLIBCXX_ALWAYS_INLINE __pointer_type
@@ -1010,6 +1016,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       }
 
 #if __cplusplus > 201703L
+#if defined _GLIBCXX_HAS_GTHREADS || _GLIBCXX_HAVE_LINUX_FUTEX
     template<typename _Tp>
       _GLIBCXX_ALWAYS_INLINE void
       wait(const _Tp* __ptr, _Val<_Tp> __old,
@@ -1034,6 +1041,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       { std::__atomic_notify(__ptr, true); }
 
       // TODO add const volatile overload
+#endif // GTHREADS || LINUX_FUTEX
 #endif // C++2a
 
     template<typename _Tp>
@@ -1289,6 +1297,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
                                       __cmpexch_failure_order(__order));
       }
 
+#if defined _GLIBCXX_HAS_GTHREADS || _GLIBCXX_HAVE_LINUX_FUTEX
       _GLIBCXX_ALWAYS_INLINE void
       wait(_Fp __old, memory_order __m = memory_order_seq_cst) const noexcept
       { __atomic_impl::wait(&_M_fp, __old, __m); }
@@ -1306,6 +1315,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       { __atomic_impl::notify_all(&_M_fp); }
 
       // TODO add const volatile overload
+#endif // GTHREADS || LINUX_FUTEX
 
       value_type
       fetch_add(value_type __i,
@@ -1444,6 +1454,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
                                       __cmpexch_failure_order(__order));
       }
 
+#if defined _GLIBCXX_HAS_GTHREADS || _GLIBCXX_HAVE_LINUX_FUTEX
       _GLIBCXX_ALWAYS_INLINE void
       wait(_Tp __old, memory_order __m = memory_order_seq_cst) const noexcept
       { __atomic_impl::wait(_M_ptr, __old, __m); }
@@ -1461,6 +1472,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       { __atomic_impl::notify_all(_M_ptr); }
 
       // TODO add const volatile overload
+#endif // GTHREADS || LINUX_FUTEX
 
     private:
       _Tp* _M_ptr;
@@ -1557,6 +1569,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
                                       __cmpexch_failure_order(__order));
       }
 
+#if defined _GLIBCXX_HAS_GTHREADS || _GLIBCXX_HAVE_LINUX_FUTEX
       _GLIBCXX_ALWAYS_INLINE void
       wait(_Tp __old, memory_order __m = memory_order_seq_cst) const noexcept
       { __atomic_impl::wait(_M_ptr, __old, __m); }
@@ -1574,6 +1587,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       { __atomic_impl::notify_all(_M_ptr); }
 
       // TODO add const volatile overload
+#endif // GTHREADS || LINUX_FUTEX
 
       value_type
       fetch_add(value_type __i,
@@ -1730,6 +1744,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
                                       __cmpexch_failure_order(__order));
       }
 
+#if defined _GLIBCXX_HAS_GTHREADS || _GLIBCXX_HAVE_LINUX_FUTEX
       _GLIBCXX_ALWAYS_INLINE void
       wait(_Fp __old, memory_order __m = memory_order_seq_cst) const noexcept
       { __atomic_impl::wait(_M_ptr, __old, __m); }
@@ -1747,6 +1762,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       { __atomic_impl::notify_all(_M_ptr); }
 
       // TODO add const volatile overload
+#endif // GTHREADS || LINUX_FUTEX
 
       value_type
       fetch_add(value_type __i,
@@ -1857,6 +1873,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
                                       __cmpexch_failure_order(__order));
       }
 
+#if defined _GLIBCXX_HAS_GTHREADS || _GLIBCXX_HAVE_LINUX_FUTEX
       _GLIBCXX_ALWAYS_INLINE void
       wait(_Tp __old, memory_order __m = memory_order_seq_cst) const noexcept
       { __atomic_impl::wait(_M_ptr, __old, __m); }
@@ -1874,6 +1891,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       { __atomic_impl::notify_all(_M_ptr); }
 
       // TODO add const volatile overload
+#endif // GTHREADS || LINUX_FUTEX
 
       _GLIBCXX_ALWAYS_INLINE value_type
       fetch_add(difference_type __d,

diff --git a/libstdc++-v3/include/bits/atomic_timed_wait.h b/libstdc++-v3/include/bits/atomic_timed_wait.h
index 405f7e9..b13f8aa 100644 (file)
--- a/libstdc++-v3/include/bits/atomic_timed_wait.h
+++ b/libstdc++-v3/include/bits/atomic_timed_wait.h
@@ -33,6 +33,7 @@
 #pragma GCC system_header
 
 #include <bits/c++config.h>
+#if defined _GLIBCXX_HAS_GTHREADS || _GLIBCXX_HAVE_LINUX_FUTEX
 #include <bits/functional_hash.h>
 #include <bits/atomic_wait.h>
 
@@ -286,4 +287,5 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     }
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace std
-#endif
+#endif // GTHREADS || LINUX_FUTEX
+#endif // _GLIBCXX_ATOMIC_TIMED_WAIT_H

diff --git a/libstdc++-v3/include/bits/atomic_wait.h b/libstdc++-v3/include/bits/atomic_wait.h
index 7b2682a..a40cff1 100644 (file)
--- a/libstdc++-v3/include/bits/atomic_wait.h
+++ b/libstdc++-v3/include/bits/atomic_wait.h
@@ -33,6 +33,7 @@
 #pragma GCC system_header
 
 #include <bits/c++config.h>
+#if defined _GLIBCXX_HAS_GTHREADS || _GLIBCXX_HAVE_LINUX_FUTEX
 #include <bits/functional_hash.h>
 #include <bits/gthr.h>
 #include <bits/std_mutex.h>
@@ -106,7 +107,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
          }
       }
 
-      template<typename _Tp>
+    template<typename _Tp>
       void
       __platform_notify(const _Tp* __addr, bool __all) noexcept
       {
@@ -175,11 +176,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
       bool
       _M_waiting() const noexcept
-       {
-         __platform_wait_t __res;
-         __atomic_load(&_M_wait, &__res, __ATOMIC_ACQUIRE);
-         return __res;
-       }
+      {
+       __platform_wait_t __res;
+       __atomic_load(&_M_wait, &__res, __ATOMIC_ACQUIRE);
+       return __res;
+      }
 
       void
       _M_notify(bool __all) noexcept
@@ -305,4 +306,5 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     }
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace std
-#endif
+#endif // GTHREADS || LINUX_FUTEX
+#endif // _GLIBCXX_ATOMIC_WAIT_H

diff --git a/libstdc++-v3/include/bits/semaphore_base.h b/libstdc++-v3/include/bits/semaphore_base.h
index 78a0b6b..5e29d37 100644 (file)
--- a/libstdc++-v3/include/bits/semaphore_base.h
+++ b/libstdc++-v3/include/bits/semaphore_base.h
@@ -33,6 +33,7 @@
 #pragma GCC system_header
 
 #include <bits/c++config.h>
+#if defined _GLIBCXX_HAS_GTHREADS || _GLIBCXX_HAVE_LINUX_FUTEX
 #include <bits/atomic_base.h>
 #include <bits/atomic_timed_wait.h>
 
@@ -161,30 +162,68 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        noexcept
       { return _M_try_acquire_until(__clock_t::now() + __rtime); }
 
-    private:
-      sem_t _M_semaphore;
-    };
+  private:
+    sem_t _M_semaphore;
+  };
 #endif // _GLIBCXX_HAVE_POSIX_SEMAPHORE
 
-    template<typename _Tp>
-      struct __atomic_semaphore
+  template<typename _Tp>
+    struct __atomic_semaphore
+    {
+      static_assert(std::is_integral_v<_Tp>);
+      static_assert(__gnu_cxx::__int_traits<_Tp>::__max
+                     <= __gnu_cxx::__int_traits<ptrdiff_t>::__max);
+      static constexpr ptrdiff_t _S_max = __gnu_cxx::__int_traits<_Tp>::__max;
+
+      explicit __atomic_semaphore(_Tp __count) noexcept
+       : _M_counter(__count)
       {
-       static_assert(std::is_integral_v<_Tp>);
-       static_assert(__gnu_cxx::__int_traits<_Tp>::__max
-                       <= __gnu_cxx::__int_traits<ptrdiff_t>::__max);
-       static constexpr ptrdiff_t _S_max = __gnu_cxx::__int_traits<_Tp>::__max;
+       __glibcxx_assert(__count >= 0 && __count <= _S_max);
+      }
 
-       explicit __atomic_semaphore(_Tp __count) noexcept
-         : _M_counter(__count)
-       {
-         __glibcxx_assert(__count >= 0 && __count <= _S_max);
-       }
+      __atomic_semaphore(const __atomic_semaphore&) = delete;
+      __atomic_semaphore& operator=(const __atomic_semaphore&) = delete;
 
-       __atomic_semaphore(const __atomic_semaphore&) = delete;
-       __atomic_semaphore& operator=(const __atomic_semaphore&) = delete;
+      _GLIBCXX_ALWAYS_INLINE void
+      _M_acquire() noexcept
+      {
+       auto const __pred = [this]
+         {
+           auto __old = __atomic_impl::load(&this->_M_counter,
+                           memory_order::acquire);
+           if (__old == 0)
+             return false;
+           return __atomic_impl::compare_exchange_strong(&this->_M_counter,
+                     __old, __old - 1,
+                     memory_order::acquire,
+                     memory_order::release);
+         };
+       auto __old = __atomic_impl::load(&_M_counter, memory_order_relaxed);
+       std::__atomic_wait(&_M_counter, __old, __pred);
+      }
+
+      bool
+      _M_try_acquire() noexcept
+      {
+       auto __old = __atomic_impl::load(&_M_counter, memory_order::acquire);
+       auto const __pred = [this, __old]
+         {
+           if (__old == 0)
+             return false;
+
+           auto __prev = __old;
+           return __atomic_impl::compare_exchange_weak(&this->_M_counter,
+                     __prev, __prev - 1,
+                     memory_order::acquire,
+                     memory_order::release);
+         };
+       return std::__atomic_spin(__pred);
+      }
 
-       _GLIBCXX_ALWAYS_INLINE void
-       _M_acquire() noexcept
+      template<typename _Clock, typename _Duration>
+       _GLIBCXX_ALWAYS_INLINE bool
+       _M_try_acquire_until(const chrono::time_point<_Clock,
+                            _Duration>& __atime) noexcept
        {
          auto const __pred = [this]
            {
@@ -193,51 +232,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
              if (__old == 0)
                return false;
              return __atomic_impl::compare_exchange_strong(&this->_M_counter,
-                       __old, __old - 1,
-                       memory_order::acquire,
-                       memory_order::release);
-           };
-         auto __old = __atomic_impl::load(&_M_counter, memory_order_relaxed);
-         std::__atomic_wait(&_M_counter, __old, __pred);
-       }
-
-       bool
-       _M_try_acquire() noexcept
-       {
-         auto __old = __atomic_impl::load(&_M_counter, memory_order::acquire);
-         auto const __pred = [this, __old]
-           {
-             if (__old == 0)
-               return false;
-
-             auto __prev = __old;
-             return __atomic_impl::compare_exchange_weak(&this->_M_counter,
-                       __prev, __prev - 1,
-                       memory_order::acquire,
-                       memory_order::release);
+                             __old, __old - 1,
+                             memory_order::acquire,
+                             memory_order::release);
            };
-         return std::__atomic_spin(__pred);
-       }
 
-       template<typename _Clock, typename _Duration>
-         _GLIBCXX_ALWAYS_INLINE bool
-         _M_try_acquire_until(const chrono::time_point<_Clock,
-                              _Duration>& __atime) noexcept
-         {
-           auto const __pred = [this]
-             {
-               auto __old = __atomic_impl::load(&this->_M_counter,
-                               memory_order::acquire);
-               if (__old == 0)
-                 return false;
-               return __atomic_impl::compare_exchange_strong(&this->_M_counter,
-                               __old, __old - 1,
-                               memory_order::acquire,
-                               memory_order::release);
-             };
-
-           auto __old = __atomic_impl::load(&_M_counter, memory_order_relaxed);
-           return __atomic_wait_until(&_M_counter, __old, __pred, __atime);
+         auto __old = __atomic_impl::load(&_M_counter, memory_order_relaxed);
+         return __atomic_wait_until(&_M_counter, __old, __pred, __atime);
        }
 
       template<typename _Rep, typename _Period>
@@ -299,4 +300,5 @@ template<ptrdiff_t __least_max_value>
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace std
 
-#endif
+#endif // GTHREADS || LINUX_FUTEX
+#endif // _GLIBCXX_SEMAPHORE_BASE_H

diff --git a/libstdc++-v3/include/std/atomic b/libstdc++-v3/include/std/atomic
index 5afe33b..fe4de24 100644 (file)
--- a/libstdc++-v3/include/std/atomic
+++ b/libstdc++-v3/include/std/atomic
@@ -165,6 +165,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     { return _M_base.compare_exchange_strong(__i1, __i2, __m); }
 
 #if __cplusplus > 201703L
+#if defined _GLIBCXX_HAS_GTHREADS || _GLIBCXX_HAVE_LINUX_FUTEX
     void wait(bool __old, memory_order __m = memory_order_seq_cst) const
       noexcept
     { _M_base.wait(__old, __m); }
@@ -176,6 +177,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
     void notify_all() const noexcept
     { _M_base.notify_all(); }
+#endif // GTHREADS || LINUX_FUTEX
 #endif
   };
 
@@ -379,6 +381,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
                                        __cmpexch_failure_order(__m)); }
 
 #if __cplusplus > 201703L
+#if defined _GLIBCXX_HAS_GTHREADS || _GLIBCXX_HAVE_LINUX_FUTEX
     void wait(_Tp __old, memory_order __m = memory_order_seq_cst) const noexcept
     {
       std::__atomic_wait(&_M_i, __old,
@@ -399,7 +402,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
     void notify_all() const noexcept
     { std::__atomic_notify(&_M_i, true); }
-#endif
+#endif // GTHREADS || LINUX_FUTEX
+#endif // C++20
 
     };
 #undef _GLIBCXX20_INIT
@@ -640,6 +644,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       }
 
 #if __cplusplus > 201703L
+#if defined _GLIBCXX_HAS_GTHREADS || _GLIBCXX_HAVE_LINUX_FUTEX
     void wait(__pointer_type __old,
              memory_order __m = memory_order_seq_cst) noexcept
     { _M_b.wait(__old, __m); }
@@ -651,6 +656,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
     void notify_all() const noexcept
     { _M_b.notify_all(); }
+#endif // GTHREADS || LINUX_FUTEX
 #endif
       __pointer_type
       fetch_add(ptrdiff_t __d,
@@ -1406,6 +1412,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
 
 #if __cplusplus > 201703L
+#if defined _GLIBCXX_HAS_GTHREADS || _GLIBCXX_HAVE_LINUX_FUTEX
   template<typename _Tp>
     inline void
     atomic_wait(const atomic<_Tp>* __a,
@@ -1429,6 +1436,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     atomic_notify_all(atomic<_Tp>* __a) noexcept
     { __a->notify_all(); }
 
+#endif // GTHREADS || LINUX_FUTEX
 #endif // C++2a
 
   // Function templates for atomic_integral and atomic_pointer operations only.

diff --git a/libstdc++-v3/include/std/semaphore b/libstdc++-v3/include/std/semaphore
index b4facde..f4b83ab 100644 (file)
--- a/libstdc++-v3/include/std/semaphore
+++ b/libstdc++-v3/include/std/semaphore
@@ -32,14 +32,16 @@
 #pragma GCC system_header
 
 #if __cplusplus > 201703L
-#define __cpp_lib_semaphore 201907L
 #include <bits/semaphore_base.h>
+#if defined _GLIBCXX_HAS_GTHREADS || _GLIBCXX_HAVE_LINUX_FUTEX
 #include <ext/numeric_traits.h>
 
 namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
+#define __cpp_lib_semaphore 201907L
+
   template<ptrdiff_t __least_max_value =
                        __gnu_cxx::__int_traits<ptrdiff_t>::__max>
     class counting_semaphore
@@ -88,5 +90,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
  using binary_semaphore = std::counting_semaphore<1>;
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace
-#endif // __cplusplus > 201703L
+#endif // GTHREADS || LINUX_FUTEX
+#endif // C++20
 #endif // _GLIBCXX_SEMAPHORE

diff --git a/libstdc++-v3/include/std/version b/libstdc++-v3/include/std/version
index 42ed7cb..cf0454d 100644 (file)
--- a/libstdc++-v3/include/std/version
+++ b/libstdc++-v3/include/std/version
@@ -226,7 +226,9 @@
 #if __cpp_lib_concepts
 # define __cpp_lib_ranges 201911L
 #endif
-#define __cpp_lib_semaphore 201907L
+#if defined _GLIBCXX_HAS_GTHREADS || _GLIBCXX_HAVE_LINUX_FUTEX
+# define __cpp_lib_semaphore 201907L
+#endif
 #define __cpp_lib_shift 201806L
 #if __cpp_lib_concepts
 # define __cpp_lib_span 202002L