On 05/06/20 17:29 -0700, Thomas Rodgers wrote:
diff --git a/libstdc++-v3/include/bits/semaphore_base.h
b/libstdc++-v3/include/bits/semaphore_base.h
new file mode 100644
index 00000000000..f0c4235d91c
--- /dev/null
+++ b/libstdc++-v3/include/bits/semaphore_base.h
@@ -0,0 +1,272 @@
+// -*- C++ -*- header.
+
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file bits/semaphore_base.h
+ * This is an internal header file, included by other library headers.
+ * Do not attempt to use it directly. @headername{semaphore}
+ */
+
+#ifndef _GLIBCXX_SEMAPHORE_BASE_H
+#define _GLIBCXX_SEMAPHORE_BASE_H 1
+
+#pragma GCC system_header
+
+#include <bits/c++config.h>
+#include <bits/atomic_base.h>
+#include <bits/atomic_timed_wait.h>
+
+#if defined _POSIX_SEMAPHORES && __has_include(<semaphore.h>)
+#define _GLIBCXX_HAVE_POSIX_SEMAPHORE 1
+#include <semaphore.h>
+#endif
+
+#include <chrono>
+#include <type_traits>
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+#ifdef _GLIBCXX_HAVE_POSIX_SEMAPHORE
+ template<ptrdiff_t __least_max_value>
+ struct __platform_semaphore
+ {
I think we want to delete the copy constructor and copy assignment
operator for this type and __atomic_semaphore.
+ using __clock_t = chrono::system_clock;
+
+ explicit __platform_semaphore(ptrdiff_t __count) noexcept
+ {
+ static_assert( __least_max_value <= SEM_VALUE_MAX, "");
+ auto __e = sem_init(&_M_semaphore, 0, __count);
+ if (__e)
+ std::terminate();
I don't think we should bother checking the return value. The failure
conditions are EINVAL if __count > SEM_VALUE_MAX, and ENOSYS if the
second argument is non-zero. Both conditions should be impossible.
+ }
+
+ ~__platform_semaphore()
+ {
+ auto __e = sem_destroy(&_M_semaphore);
+ if (__e)
+ std::terminate();
Likewise here. The only error condition is EINVAL, which is impossible
if _M_semaphore is a valid semaphore, which the constructor already
ensured.
If somehow _M_semaphore is invalid it means the user broke something
(e.g. by scribbling over *this) and we don't need to detect and handle
that case.
+ }
+
+ _GLIBCXX_ALWAYS_INLINE void
+ acquire() noexcept
+ {
+ auto __err = sem_wait(&_M_semaphore);
+ if (__err)
+ std::terminate();
What about the EINTR case where the wait is interrupted by a signal?
I think that should retry, but it shouldn't terminate.
+ template<typename _Duration>
+ bool
+ __try_acquire_until_impl(const chrono::time_point<__clock_t>& __atime)
noexcept
+ {
+ auto __s = chrono::time_point_cast<chrono::seconds>(__atime);
+ auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
+
+ struct timespec __ts =
+ {
+ static_cast<std::time_t>(__s.time_since_epoch().count()),
+ static_cast<long>(__ns.count())
+ };
+
+ auto __err = sem_timedwait(&_M_semaphore, &__ts);
+ if (__err && (errno == ETIMEDOUT))
+ return false;
+ else if (__err)
+ std::terminate();
I think this needs to handle both EINTR and EINVAL:
EINVAL The value of abs_timeout.tv_nsecs is less than 0, or greater than
or equal to 1000 million.
Alternatively, just return immediately without waiting for a time
before the epoch, i.e. __abs_time < time_point<__clock_t>{}
Otherwise time_point(-20ns) will cause EINVAL and terminate.
+ return true;
+ }
+
+ template<typename _Clock, typename _Duration>
+ bool
+ try_acquire_until(const chrono::time_point<_Clock, _Duration>& __atime)
noexcept
+ {
+ if constexpr (std::is_same<__clock_t, _Clock>::value)
+ {
+ return __try_acquire_until_impl(__atime);
+ }
+ else
+ {
+ const typename _Clock::time_point __c_entry = _Clock::now();
+ const __clock_t __s_entry = __clock_t::now();
+ const auto __delta = __atime - __c_entry;
+ const auto __s_atime = __s_entry + __delta;
+ if (__try_acquire_until_impl(__s_atime))
+ return true;
+
+ // We got a timeout when measured against __clock_t but
+ // we need to check against the caller-supplied clock
+ // to tell whether we should return a timeout.
+ return (_Clock::now() < __atime);
+ }
+ }
+
+ template<typename _Rep, typename _Period>
+ _GLIBCXX_ALWAYS_INLINE bool
+ try_acquire_for(const chrono::duration<_Rep, _Period>& __rtime) noexcept
+ { return try_acquire_until(__clock_t::now() + __rtime); }
+
+ template<typename _Clock, typename _Duration>
+ _GLIBCXX_ALWAYS_INLINE void
+ release(ptrdiff_t __update) noexcept
+ {
+ do
+ {
+ auto __err = sem_post(&_M_semaphore);
+ if (__err)
+ std::terminate();
+ } while (--__update);
+ }
+
+ private:
+ sem_t _M_semaphore;
+ };
+#endif // _GLIBCXX_HAVE_POSIX_SEMAPHORE
+
+ template<typename _Tp>
+ struct __atomic_semaphore
+ {
Do we want a static_assert(is_integral_v<_Tp>) or similar?
+ explicit __atomic_semaphore(_Tp __count)
Add noexcept?
+ : _M_a(__count)
+ { }
+
+ _GLIBCXX_ALWAYS_INLINE void
+ acquire() noexcept
+ {
+ auto const __pred = [this]
+ {
+ auto __old = __atomic_impl::load(&this->_M_a,
+ memory_order::acquire);
Would it be simpler to just use a local atomic_ref to manipulate _M_a
here, and in the other members performing atomic ops on that member?
+ if (__old == 0)
+ return false;
+ return __atomic_impl::compare_exchange_strong(&this->_M_a,
+ __old, __old - 1,
+ memory_order::acquire,
+ memory_order::release);
+ };
+ auto __old = __atomic_impl::load(&_M_a, memory_order_relaxed);
+ __atomic_wait(&_M_a, __old, __pred);
Strictly speaking, this __atomic_wait would violate the "all accesses
to that object shall exclusively occur through those atomic_ref
instances" rule. But we know that it's actually OK because
__atomic_wait is only performing atomic ops on the same location.
+ }
+
+ bool
+ try_acquire() noexcept
+ {
+ auto __old = __atomic_impl::load(&_M_a, memory_order::acquire);
+ if (__old == 0)
+ return false;
+
+ return __atomic_spin([this, &__old]
+ {
+ return __atomic_impl::compare_exchange_weak(&this->_M_a,
+ __old, __old - 1,
+ memory_order::acquire,
+ memory_order::release);
+ });
+ }
+
+ template<typename _Clock, typename _Duration>
+ _GLIBCXX_ALWAYS_INLINE bool
+ try_acquire_until(const chrono::time_point<_Clock, _Duration>&
__atime) noexcept
+ {
+ auto const __pred = [this]
+ {
+ auto __old = __atomic_impl::load(&this->_M_a,
+ memory_order::acquire);
+ if (__old == 0)
+ return false;
+ return __atomic_impl::compare_exchange_strong(&this->_M_a,
+ __old, __old - 1,
+ memory_order::acquire,
+ memory_order::release);
+ };
+
+ auto __old = __atomic_impl::load(&_M_a, memory_order_relaxed);
+ return __atomic_wait_until(&_M_a, __old, __pred, __atime);
+ }
+
+ template<typename _Rep, typename _Period>
+ _GLIBCXX_ALWAYS_INLINE bool
+ try_acquire_for(const chrono::duration<_Rep, _Period>& __rtime) noexcept
+ {
+ auto const __pred = [this]
+ {
+ auto __old = __atomic_impl::load(&this->_M_a,
+ memory_order::acquire);
+ if (__old == 0)
+ return false;
+ return __atomic_impl::compare_exchange_strong(&this->_M_a,
+ __old, __old - 1,
+ memory_order::acquire,
+ memory_order::release);
+ };
+
+ auto __old = __atomic_impl::load(&_M_a, memory_order_relaxed);
+ return __atomic_wait_for(&_M_a, __old, __pred, __rtime);
+ }
+
+ _GLIBCXX_ALWAYS_INLINE void
+ release(ptrdiff_t __update) noexcept
+ {
+ if (0 < __atomic_impl::fetch_add(&_M_a, __update, memory_order_release))
+ return;
+ if (__update > 1)
+ __atomic_impl::notify_all(&_M_a);
+ else
+ __atomic_impl::notify_one(&_M_a);
+ }
+
+ private:
+ alignas(__alignof__(_Tp)) _Tp _M_a;
+ };
+
+#ifdef _GLIBCXX_REQUIRE_POSIX_SEMAPHORE
What is this case for? This macro seems to only exist for use by a
single testcase.
Is it supposed to be something users can set? If so, it needs to be
documented as ABI-breaking and as implying that counting_semaphore
cannot be use with counts higher than SEM_VALUE_MAX.
+ template<ptrdiff_t __least_max_value>
+ using __semaphore_base = __platform_semaphore<__least_max_value>;
+#else
+# ifdef _GLIBCXX_HAVE_LINUX_FUTEX
+ template<ptrdiff_t __least_max_value>
+ using __semaphore_base = conditional_t<(
+ __least_max_value >= 0
This condition is redundant, we already know that counting_semaphore
has checked the value is non-negative.
+ && __least_max_value <=
__detail::__platform_wait_max_value),
+ __atomic_semaphore<__detail::__platform_wait_t>,
+ __atomic_semaphore<ptrdiff_t>>;
+
+// __platform_semaphore
+# elif defined _GLIBCXX_HAVE_POSIX_SEMAPHORE
+ template<ptrdiff_t __least_max_value>
+ using __semaphore_base = conditional_t<(
+ __least_max_value >= 0
Redundant condition again.
+ && __least_max_value <= SEM_VALUE_MAX),
+ __platform_semaphore<__least_max_value>,
+ __atomic_semaphore<ptrdiff_t>>;
+# else
+ template<ptrdiff_t __least_max_value>
+ using __semaphore_base = __atomic_semaphore<ptrdiff_t>;
+# endif
+#endif
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace std
+
+#endif
diff --git a/libstdc++-v3/include/std/atomic b/libstdc++-v3/include/std/atomic
index a455286a784..3f18774031d 100644
--- a/libstdc++-v3/include/std/atomic
+++ b/libstdc++-v3/include/std/atomic
@@ -163,6 +163,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
compare_exchange_strong(bool& __i1, bool __i2,
memory_order __m = memory_order_seq_cst) volatile noexcept
{ return _M_base.compare_exchange_strong(__i1, __i2, __m); }
+
+#if __cplusplus > 201703L
+ void wait(bool __old, memory_order __m = memory_order_seq_cst) const
noexcept
+ { _M_base.wait(__old, __m); }
+
+ // TODO add const volatile overload
+
+ void notify_one() const noexcept
+ { _M_base.notify_one(); }
+
+ void notify_all() const noexcept
+ { _M_base.notify_all(); }
+#endif
};
#if __cplusplus <= 201703L
@@ -352,6 +365,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
memory_order __m = memory_order_seq_cst) volatile noexcept
{ return compare_exchange_strong(__e, __i, __m,
__cmpexch_failure_order(__m)); }
+#if __cplusplus > 201703L
+ void wait(_Tp __old, memory_order __m = memory_order_seq_cst) noexcept
+ { _M_i.wait(__old, __m); }
This can't be right. _M_i is of type _Tp in std::atomic<_Tp>, it doesn't
have a wait member function.
If this compiles it suggests there are no tests for these members on
the primary template, e.g. something like:
void
test01()
{
struct S { int i; };
std:::atomic<S> s;
s.wait();
}
+
+ // TODO add const volatile overload
+
+ void notify_one() const noexcept
+ { _M_i.notify_one(); }
+
+ void notify_all() const noexcept
+ { _M_i.notify_all(); }
+#endif
+
};
#undef _GLIBCXX20_INIT
@@ -590,6 +616,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__cmpexch_failure_order(__m));
}
+#if __cplusplus > 201703L
+ void wait(__pointer_type __old, memory_order __m = memory_order_seq_cst)
noexcept
+ { _M_b.wait(__old, __m); }
+
+ // TODO add const volatile overload
+
+ void notify_one() const noexcept
+ { _M_b.notify_one(); }
+
+ void notify_all() const noexcept
+ { _M_b.notify_all(); }
+#endif
__pointer_type
fetch_add(ptrdiff_t __d,
memory_order __m = memory_order_seq_cst) noexcept
@@ -1342,6 +1380,29 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
memory_order_seq_cst);
}
+
+#if __cplusplus > 201703L
+ template<typename _Tp>
+ inline void atomic_wait(const atomic<_Tp>* __a,
Newline after the return type.
+ typename std::atomic<_Tp>::value_type __old)
noexcept
+ { __a->wait(__old); }
+
+ template<typename _Tp>
+ inline void atomic_wait_explicit(const atomic<_Tp>* __a,
And here.
+ typename std::atomic<_Tp>::value_type
__old,
+ std::memory_order __m) noexcept
+ { __a->wait(__old, __m); }
+
+ template<typename _Tp>
+ inline void atomic_notify_one(atomic<_Tp>* __a) noexcept
+ { __a->notify_one(); }
+
+ template<typename _Tp>
+ inline void atomic_notify_all(atomic<_Tp>* __a) noexcept
+ { __a->notify_all(); }
+
+#endif // C++2a
+
// Function templates for atomic_integral and atomic_pointer operations only.
// Some operations (and, or, xor) are only available for atomic integrals,
// which is implemented by taking a parameter of type __atomic_base<_ITp>*.
diff --git a/libstdc++-v3/include/std/latch b/libstdc++-v3/include/std/latch
new file mode 100644
index 00000000000..aa5299d9fdd
--- /dev/null
+++ b/libstdc++-v3/include/std/latch
@@ -0,0 +1,90 @@
+// <latch> -*- C++ -*-
+
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file include/latch
+ * This is a Standard C++ Library header.
+ */
+
+#ifndef _GLIBCXX_LATCH
+#define _GLIBCXX_LATCH
+
+#pragma GCC system_header
+
+#if __cplusplus > 201703L
+#define __cpp_lib_latch 201907L
+
+#include <bits/atomic_base.h>
+#include <ext/numeric_traits.h>
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+ class latch
+ {
+ public:
+ static constexpr
+ _GLIBCXX_ALWAYS_INLINE ptrdiff_t
I don't think we need _GLIBCXX_ALWAYS_INLINE here.
+ max() noexcept
+ { return __gnu_cxx::__numeric_traits<ptrdiff_t>::__max; }
+
+ constexpr explicit latch(ptrdiff_t __expected) : _M_a(__expected) { }
Add noexcept.
+
+ ~latch() = default;
+ latch(const latch&) = delete;
+ latch& operator=(const latch&) = delete;
+
+ _GLIBCXX_ALWAYS_INLINE void
+ count_down(ptrdiff_t __update = 1)
+ {
+ auto const __old = __atomic_impl::fetch_sub(&_M_a, __update,
memory_order::release);
It looks like this could use atomic_ref too, although there'd be less
benefit here.
+ if (__old == __update)
+ __atomic_impl::notify_all(&_M_a);
+ }
+
+ _GLIBCXX_ALWAYS_INLINE bool
+ try_wait() const noexcept
+ { return __atomic_impl::load(&_M_a, memory_order::acquire) == 0; }
+
+ _GLIBCXX_ALWAYS_INLINE void
+ wait() const
+ {
+ auto const __old = __atomic_impl::load(&_M_a, memory_order::acquire);
+ __atomic_wait(&_M_a, __old, [this] { return this->try_wait(); });
+ }
+
+ _GLIBCXX_ALWAYS_INLINE void
+ arrive_and_wait(ptrdiff_t __update = 1)
+ {
+ count_down();
+ wait();
+ }
+
+ private:
+ alignas(__alignof__(ptrdiff_t)) ptrdiff_t _M_a;
+ };
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace
+#endif // __cplusplus > 201703L
+#endif // _GLIBCXX_LATCH
diff --git a/libstdc++-v3/include/std/semaphore
b/libstdc++-v3/include/std/semaphore
new file mode 100644
index 00000000000..90cf3244647
--- /dev/null
+++ b/libstdc++-v3/include/std/semaphore
@@ -0,0 +1,86 @@
+// <semaphore> -*- C++ -*-
+
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file include/semaphore
+ * This is a Standard C++ Library header.
+ */
+
+#ifndef _GLIBCXX_SEMAPHORE
+#define _GLIBCXX_SEMAPHORE
+
+#pragma GCC system_header
+
+#if __cplusplus > 201703L
+#define __cpp_lib_semaphore 201907L
+#include <bits/semaphore_base.h>
+#include <ext/numeric_traits.h>
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+ template<ptrdiff_t __least_max_value =
+ __gnu_cxx::__numeric_traits<ptrdiff_t>::__max>
+ class counting_semaphore
+ {
+ static_assert(__least_max_value >=0, "");
Add a space before the 0. Get rid of the empty string literal.
+
+ __semaphore_base<__least_max_value> _M_sem;
"base" seems a bit misleading here when it's a member not a base
class. Would __semaphore_impl be better?
+
+ public:
+ explicit counting_semaphore(ptrdiff_t __desired) noexcept
+ : _M_sem(__desired)
+ { }
+
+ ~counting_semaphore() = default;
+
+ counting_semaphore(const counting_semaphore&) = delete;
+ counting_semaphore& operator=(const counting_semaphore&) = delete;
+
+ static constexpr ptrdiff_t max() noexcept
+ { return __least_max_value; }
+
+ void release(ptrdiff_t __update = 1)
We can add noexcept here, since we know neither of the
__semaphore_base types will throw. If you envision alternative
implementations in future, then it would be futureproof to use
noexcept(noexcept(_M_sem.release(1)))
+ { _M_sem.release(__update); }
+
+ void acquire()
Same here.
+ { _M_sem.acquire(); }
+
+ bool try_acquire() noexcept
+ { return _M_sem.try_acquire(); }
+
+ template<class _Rep, class _Period>
+ bool try_acquire_for(const std::chrono::duration<_Rep, _Period>&
__rel_time)
Newline after the return type (the line is too long otherwise).
This one can potentially throw because of the duration arithmetic on
_Rep objects.
+ { return _M_sem.try_acquire_for(__rel_time); }
+
+ template<class _Clock, class _Duration>
+ bool try_acquire_until(const std::chrono::time_point<_Clock,
_Duration>& __abs_time)
Newline after the return type (I think it's still going to be too
long).
+ { return _M_sem.try_acquire_until(__abs_time); }
+ };
+
+ using binary_semaphore = std::counting_semaphore<1>;
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace
+#endif // __cplusplus > 201703L
+#endif // _GLIBCXX_SEMAPHORE
diff --git a/libstdc++-v3/include/std/version b/libstdc++-v3/include/std/version
index c6bde2cfbda..f09da3344f7 100644
--- a/libstdc++-v3/include/std/version
+++ b/libstdc++-v3/include/std/version
@@ -189,6 +189,8 @@
#endif
#define __cpp_lib_type_identity 201806L
#define __cpp_lib_unwrap_ref 201811L
+#define __cpp_lib_semaphore 201907L
+#define __cpp_lib_latch 201907L
You're adding these macros in the freestanding section, and these
aren't freestanding headers. They need to be in the _GLIBCXX_HOSTED
block, and the macros need to be in alphabetical order.
#if _GLIBCXX_HOSTED
#undef __cpp_lib_array_constexpr
diff --git
a/libstdc++-v3/testsuite/29_atomics/atomic/wait_notify/atomic_refs.cc
b/libstdc++-v3/testsuite/29_atomics/atomic/wait_notify/atomic_refs.cc
new file mode 100644
index 00000000000..1ced9d44b20
--- /dev/null
+++ b/libstdc++-v3/testsuite/29_atomics/atomic/wait_notify/atomic_refs.cc
@@ -0,0 +1,103 @@
+// { dg-options "-std=gnu++2a -pthread -latomic -L../../libatomic/.libs" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <atomic>
+#include <thread>
+#include <mutex>
+#include <condition_variable>
+#include <chrono>
+#include <type_traits>
+
+#include <testsuite_hooks.h>
+
+template<typename Tp>
+Tp check_wait_notify(Tp val1, Tp val2)
+{
+ using namespace std::literals::chrono_literals;
+
+ std::mutex m;
+ std::condition_variable cv;
+
+ Tp aa = val1;
+ std::atomic_ref<Tp> a(aa);
+ std::thread t([&]
+ {
+ cv.notify_one();
+ a.wait(val1);
+ if (a.load() != val2)
+ a = val1;
+ });
+ std::unique_lock<std::mutex> l(m);
+ cv.wait(l);
+ std::this_thread::sleep_for(100ms);
+ a.store(val2);
+ a.notify_one();
+ t.join();
+ return a.load();
+}
+
+template<typename Tp,
+ bool = std::is_integral_v<Tp>
+ || std::is_floating_point_v<Tp>>
+struct check;
+
+template<typename Tp>
+struct check<Tp, true>
+{
+ check()
+ {
+ Tp a = 0;
+ Tp b = 42;
+ VERIFY(check_wait_notify(a, b) == b);
+ }
+};
+
+template<typename Tp>
+struct check<Tp, false>
+{
+ check(Tp b)
+ {
+ Tp a;
+ VERIFY(check_wait_notify(a, b) == b);
+ }
+};
+
+struct foo
+{
+ long a = 0;
+ long b = 0;
+
+ foo& operator=(foo const&) = default;
+
+ friend bool
+ operator==(foo const& rhs, foo const& lhs)
+ { return rhs.a == lhs.a && rhs.b == lhs.b; }
+};
+
+int
+main ()
+{
+ check<long>();
+ check<double>();
+ check<foo>({42, 48});
+ return 0;
+}
diff --git a/libstdc++-v3/testsuite/29_atomics/atomic/wait_notify/bool.cc
b/libstdc++-v3/testsuite/29_atomics/atomic/wait_notify/bool.cc
new file mode 100644
index 00000000000..b9fc063c66f
--- /dev/null
+++ b/libstdc++-v3/testsuite/29_atomics/atomic/wait_notify/bool.cc
@@ -0,0 +1,59 @@
+// { dg-options "-std=gnu++2a -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <atomic>
+#include <thread>
+#include <mutex>
+#include <condition_variable>
+#include <type_traits>
+#include <chrono>
+
+#include <testsuite_hooks.h>
+
+int
+main ()
+{
+ using namespace std::literals::chrono_literals;
+
+ std::mutex m;
+ std::condition_variable cv;
+
+ std::atomic<bool> a(false);
+ std::atomic<bool> b(false);
+ std::thread t([&]
+ {
+ cv.notify_one();
+ a.wait(false);
+ if (a.load())
+ {
+ b.store(true);
+ }
+ });
+ std::unique_lock<std::mutex> l(m);
+ cv.wait(l);
+ std::this_thread::sleep_for(100ms);
+ a.store(true);
+ a.notify_one();
+ t.join();
+ VERIFY( b.load() );
+ return 0;
+}
diff --git a/libstdc++-v3/testsuite/29_atomics/atomic/wait_notify/floats.cc
b/libstdc++-v3/testsuite/29_atomics/atomic/wait_notify/floats.cc
new file mode 100644
index 00000000000..1d032085752
--- /dev/null
+++ b/libstdc++-v3/testsuite/29_atomics/atomic/wait_notify/floats.cc
@@ -0,0 +1,32 @@
+// { dg-options "-std=gnu++2a -pthread -latomic -L../../libatomic/.libs" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+#include "generic.h"
+
+int
+main ()
+{
+ check<float> f;
+ check<double> d;
+ check<long double> l;
+ return 0;
+}
diff --git a/libstdc++-v3/testsuite/29_atomics/atomic/wait_notify/generic.h
b/libstdc++-v3/testsuite/29_atomics/atomic/wait_notify/generic.h
new file mode 100644
index 00000000000..0da374ece87
--- /dev/null
+++ b/libstdc++-v3/testsuite/29_atomics/atomic/wait_notify/generic.h
@@ -0,0 +1,88 @@
+// -*- C++ -*- header.
This isn't a header. I don't think this modeline should be here.
The test seems to be missing any dg-options, target selectors etc.
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <atomic>
+#include <thread>
+#include <mutex>
+#include <condition_variable>
+#include <chrono>
+
+#include <testsuite_hooks.h>
+
+template<typename Tp>
+Tp check_wait_notify(Tp val1, Tp val2)
+{
+ using namespace std::literals::chrono_literals;
+
+ std::mutex m;
+ std::condition_variable cv;
+
+ std::atomic<Tp> a(val1);
+ std::thread t([&]
+ {
+ cv.notify_one();
+ a.wait(val1);
+ if (a.load() != val2)
+ a = val1;
+ });
+ std::unique_lock<std::mutex> l(m);
+ cv.wait(l);
+ std::this_thread::sleep_for(100ms);
+ a.store(val2);
+ a.notify_one();
+ t.join();
+ return a.load();
+}
+
+template<typename Tp>
+Tp check_atomic_wait_notify(Tp val1, Tp val2)
+{
+ using namespace std::literals::chrono_literals;
+
+ std::mutex m;
+ std::condition_variable cv;
+
+ std::atomic<Tp> a(val1);
+ std::thread t([&]
+ {
+ cv.notify_one();
+ std::atomic_wait(&a, val1);
+ if (a.load() != val2)
+ a = val1;
+ });
+ std::unique_lock<std::mutex> l(m);
+ cv.wait(l);
+ std::this_thread::sleep_for(100ms);
+ a.store(val2);
+ std::atomic_notify_one(&a);
+ t.join();
+ return a.load();
+}
+
+template<typename Tp>
+struct check
+{
+ check()
+ {
+ Tp a = 0;
+ Tp b = 42;
+ VERIFY(check_wait_notify(a, b) == b);
+ VERIFY(check_atomic_wait_notify(a, b) == b);
+ }
+};
diff --git a/libstdc++-v3/testsuite/29_atomics/atomic/wait_notify/integrals.cc
b/libstdc++-v3/testsuite/29_atomics/atomic/wait_notify/integrals.cc
new file mode 100644
index 00000000000..2afd19a7d14
--- /dev/null
+++ b/libstdc++-v3/testsuite/29_atomics/atomic/wait_notify/integrals.cc
@@ -0,0 +1,56 @@
+// { dg-options "-std=gnu++2a -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+#include "generic.h"
+
+int
+main ()
+{
+ // check<bool> bb;
+ check<char> ch;
+ check<signed char> sch;
+ check<unsigned char> uch;
+ check<short> s;
+ check<unsigned short> us;
+ check<int> i;
+ check<unsigned int> ui;
+ check<long> l;
+ check<unsigned long> ul;
+ check<long long> ll;
+ check<unsigned long long> ull;
+
+ check<wchar_t> wch;
+ check<char8_t> ch8;
+ check<char16_t> ch16;
+ check<char32_t> ch32;
+
+ check<int8_t> i8;
+ check<int16_t> i16;
+ check<int32_t> i32;
+ check<int64_t> i64;
+
+ check<uint8_t> u8;
+ check<uint16_t> u16;
+ check<uint32_t> u32;
+ check<uint64_t> u64;
+ return 0;
+}
diff --git a/libstdc++-v3/testsuite/29_atomics/atomic/wait_notify/pointers.cc
b/libstdc++-v3/testsuite/29_atomics/atomic/wait_notify/pointers.cc
new file mode 100644
index 00000000000..8531bb2e788
--- /dev/null
+++ b/libstdc++-v3/testsuite/29_atomics/atomic/wait_notify/pointers.cc
@@ -0,0 +1,59 @@
+// { dg-options "-std=gnu++2a -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <atomic>
+#include <thread>
+#include <mutex>
+#include <condition_variable>
+#include <type_traits>
+#include <chrono>
+
+#include <testsuite_hooks.h>
+
+int
+main ()
+{
+ using namespace std::literals::chrono_literals;
+
+ std::mutex m;
+ std::condition_variable cv;
+
+ long aa;
+ long bb;
+
+ std::atomic<long*> a(nullptr);
+ std::thread t([&]
+ {
+ cv.notify_one();
+ a.wait(nullptr);
+ if (a.load() == &aa)
+ a.store(&bb);
+ });
+ std::unique_lock<std::mutex> l(m);
+ cv.wait(l);
+ std::this_thread::sleep_for(100ms);
+ a.store(&aa);
+ a.notify_one();
+ t.join();
+ VERIFY( a.load() == &bb);
+ return 0;
+}
diff --git a/libstdc++-v3/testsuite/30_threads/latch/1.cc
b/libstdc++-v3/testsuite/30_threads/latch/1.cc
new file mode 100644
index 00000000000..aa203cdf525
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/latch/1.cc
@@ -0,0 +1,27 @@
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <latch>
+
+#ifndef __cpp_lib_latch
+# error "Feature-test macro for latch missing in <latch>"
+#elif __cpp_lib_latch!= 201907L
+# error "Feature-test macro for latch has wrong value in <latch>"
+#endif
diff --git a/libstdc++-v3/testsuite/30_threads/latch/2.cc
b/libstdc++-v3/testsuite/30_threads/latch/2.cc
new file mode 100644
index 00000000000..756727f33b3
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/latch/2.cc
@@ -0,0 +1,27 @@
+// Copyright (C) 2019-2020 Free Software Foundation, Inc.
Just 2020.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <version>
+
+#ifndef __cpp_lib_latch
+# error "Feature-test macro for latch missing in <version>"
+#elif __cpp_lib_latch != 201907L
+# error "Feature-test macro for latch has wrong value in <version>"
+#endif
diff --git a/libstdc++-v3/testsuite/30_threads/latch/3.cc
b/libstdc++-v3/testsuite/30_threads/latch/3.cc
new file mode 100644
index 00000000000..10bb500d261
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/latch/3.cc
@@ -0,0 +1,50 @@
+// Copyright (C) 2019-2020 Free Software Foundation, Inc.
+//
Just 2020.
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+//
+#include <latch>
+#include <atomic>
+#include <thread>
+#include <testsuite_hooks.h>
+
+int main()
+{
+ std::atomic<int> a(0);
+
+ std::latch l(3);
+
+ VERIFY( !l.try_wait() );
+
+ auto fn = [&]
+ {
+ ++a;
+ l.count_down();
+ };
+
+ std::thread t0(fn);
+ std::thread t1(fn);
+
+ l.arrive_and_wait();
+ t0.join();
+ t1.join();
+
+ VERIFY( l.try_wait() );
+}
diff --git a/libstdc++-v3/testsuite/30_threads/semaphore/1.cc
b/libstdc++-v3/testsuite/30_threads/semaphore/1.cc
new file mode 100644
index 00000000000..1bbca687fc3
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/1.cc
@@ -0,0 +1,27 @@
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <semaphore>
+
+#ifndef __cpp_lib_semaphore
+# error "Feature-test macro for semaphore missing in <semaphore>"
+#elif __cpp_lib_semaphore != 201907L
+# error "Feature-test macro for semaphore has wrong value in <semaphore>"
+#endif
diff --git a/libstdc++-v3/testsuite/30_threads/semaphore/2.cc
b/libstdc++-v3/testsuite/30_threads/semaphore/2.cc
new file mode 100644
index 00000000000..b96b8a59c64
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/2.cc
@@ -0,0 +1,27 @@
+// Copyright (C) 2019-2020 Free Software Foundation, Inc.
Just 2020.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <version>
+
+#ifndef __cpp_lib_semaphore
+# error "Feature-test macro for semaphore missing in <version>"
+#elif __cpp_lib_semaphore != 201907L
+# error "Feature-test macro for semaphore has wrong value in <version>"
+#endif
diff --git a/libstdc++-v3/testsuite/30_threads/semaphore/least_max_value_neg.cc
b/libstdc++-v3/testsuite/30_threads/semaphore/least_max_value_neg.cc
new file mode 100644
index 00000000000..1ac9d261ca5
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/least_max_value_neg.cc
@@ -0,0 +1,28 @@
+// Copyright (C) 2019-2020 Free Software Foundation, Inc.
Just 2020.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <semaphore>
+
+int main()
+{
+ std::counting_semaphore<-1> sem(2);
+ return 0;
+}
+// { dg-error "static assertion failed" "" { target *-*-* } 0 }
diff --git a/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire.cc
b/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire.cc
new file mode 100644
index 00000000000..d38cef86cfc
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire.cc
@@ -0,0 +1,55 @@
+// Copyright (C) 2019-2020 Free Software Foundation, Inc.
Just 2020.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+#include <semaphore>
+#include <limits>
+#include <cstddef>
+#include <testsuite_hooks.h>
+
+void test01()
+{
+ std::counting_semaphore<10> s(3);
+
+ s.acquire();
+ VERIFY( s.try_acquire() );
+ VERIFY( s.try_acquire() );
+ VERIFY( !s.try_acquire() );
+ s.release();
+ VERIFY( s.try_acquire() );
+}
+
+void test02()
+{
+ std::binary_semaphore s(1);
+
+ s.acquire();
+ VERIFY( !s.try_acquire() );
+ s.release();
+ VERIFY( s.try_acquire() );
+}
+
+
+int main()
+{
+ test01();
+ test02();
+}
diff --git a/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_for.cc
b/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_for.cc
new file mode 100644
index 00000000000..965554a3c28
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_for.cc
@@ -0,0 +1,85 @@
+// Copyright (C) 2019-2020 Free Software Foundation, Inc.
Just 2020.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+#include <semaphore>
+#include <chrono>
+#include <thread>
+#include <atomic>
+#include <testsuite_hooks.h>
+
+void test01()
+{
+ using namespace std::chrono_literals;
+ std::counting_semaphore<10> s(2);
+ s.acquire();
+
+ auto const dur = 250ms;
+ {
+ auto const t0 = std::chrono::steady_clock::now();
+ VERIFY( s.try_acquire_for(dur) );
+ auto const diff = std::chrono::steady_clock::now() - t0;
+ VERIFY( diff < dur );
+ }
+
+ {
+ auto const t0 = std::chrono::steady_clock::now();
+ VERIFY( !s.try_acquire_for(dur) );
+ auto const diff = std::chrono::steady_clock::now() - t0;
+ VERIFY( diff >= dur );
+ }
+}
+
+void test02()
+{
+ using namespace std::chrono_literals;
+ std::binary_semaphore s(1);
+ std::atomic<int> a(0), b(0);
+ std::thread t([&] {
+ a.wait(0);
+ auto const dur = 250ms;
+ VERIFY( !s.try_acquire_for(dur) );
+ b++;
+ b.notify_one();
+
+ a.wait(1);
+ VERIFY( s.try_acquire_for(dur) );
+ b++;
+ b.notify_one();
+ });
+ t.detach();
+
+ s.acquire();
+ a++;
+ a.notify_one();
+ b.wait(0);
+ s.release();
+ a++;
+ a.notify_one();
+
+ b.wait(1);
+}
+
+int main()
+{
+ test01();
+ test02();
+}
diff --git a/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_futex.cc
b/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_futex.cc
new file mode 100644
index 00000000000..5e05606e97f
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_futex.cc
@@ -0,0 +1,51 @@
+// Copyright (C) 2019-2020 Free Software Foundation, Inc.
Just 2020.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+#include <semaphore>
+#include <limits>
+#include <cstddef>
+#include <testsuite_hooks.h>
+
+#ifdef _GLIBCXX_HAVE_LINUX_FUTEX
+void test01()
+{
+ // the implementation optimizes for values of least_max_t that can fit
+ // in a futex, make sure we cover the case where least_max_t doesn't
+ auto constexpr least_max_t = std::numeric_limits<std::ptrdiff_t>::max();
+ std::counting_semaphore<least_max_t> s(3);
+
+ s.acquire();
+ VERIFY( s.try_acquire() );
+ VERIFY( s.try_acquire() );
+ VERIFY( !s.try_acquire() );
+ s.release();
+ VERIFY( s.try_acquire() );
+}
+
+#endif
+
+int main()
+{
+#ifdef _GLIBCXX_HAVE_LINUX_FUTEX
+ test01();
+#endif
+}
diff --git a/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_posix.cc
b/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_posix.cc
new file mode 100644
index 00000000000..bf99fd3cf8f
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_posix.cc
@@ -0,0 +1,169 @@
+// Copyright (C) 2019-2020 Free Software Foundation, Inc.
Just 2020.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+#include <semaphore>
+#include <chrono>
+#include <thread>
+#include <atomic>
+#include <testsuite_hooks.h>
+
+#ifdef _GLIBCXX_HAVE_POSIX_SEMAPHORE
+ // The implementation supports posix as an implementation strategy
+ // make sure we cover that case
+#define _GLIBCXX_REQUIRE_POSIX_SEMAPHORE
This macro is defined too late to do anything. It would ned to be
defined before including <semaphore> to have any effect.
+void test01()
+{
+ std::counting_semaphore<10> s(3);
+
+ s.acquire();
+ VERIFY( s.try_acquire() );
+ VERIFY( s.try_acquire() );
+ VERIFY( !s.try_acquire() );
+ s.release();
+ VERIFY( s.try_acquire() );
+}
+
+void test02()
+{
+ using namespace std::chrono_literals;
+ std::counting_semaphore<10> s(2);
+ s.acquire();
+
+ auto const dur = 250ms;
+ {
+ auto const t0 = std::chrono::steady_clock::now();
+ VERIFY( s.try_acquire_for(dur) );
+ auto const diff = std::chrono::steady_clock::now() - t0;
+ VERIFY( diff < dur );
+ }
+
+ {
+ auto const t0 = std::chrono::steady_clock::now();
+ VERIFY( !s.try_acquire_for(dur) );
+ auto const diff = std::chrono::steady_clock::now() - t0;
+ VERIFY( diff >= dur );
+ }
+}
+
+void test03()
+{
+ using namespace std::chrono_literals;
+ std::binary_semaphore s(1);
+ std::atomic<int> a(0), b(0);
+ std::thread t([&] {
+ a.wait(0);
+ auto const dur = 250ms;
+ VERIFY( !s.try_acquire_for(dur) );
+ b++;
+ b.notify_one();
+
+ a.wait(1);
+ VERIFY( s.try_acquire_for(dur) );
+ b++;
+ b.notify_one();
+ });
+ t.detach();
+
+ s.acquire();
+ a++;
+ a.notify_one();
+ b.wait(0);
+ s.release();
+ a++;
+ a.notify_one();
+
+ b.wait(1);
+}
+
+void test04()
+{
+ using namespace std::chrono_literals;
+ std::counting_semaphore<10> s(2);
+ s.acquire();
+
+ auto const dur = 250ms;
+ {
+ auto const at = std::chrono::system_clock::now() + dur;
+ auto const t0 = std::chrono::steady_clock::now();
+ VERIFY( s.try_acquire_until(at) );
+ auto const diff = std::chrono::steady_clock::now() - t0;
+ VERIFY( diff < dur );
+ }
+
+ {
+ auto const at = std::chrono::system_clock::now() + dur;
+ auto const t0 = std::chrono::steady_clock::now();
+ VERIFY( !s.try_acquire_until(at) );
+ auto const diff = std::chrono::steady_clock::now() - t0;
+ VERIFY( diff >= dur );
+ }
+}
+
+void test05()
+{
+ using namespace std::chrono_literals;
+ std::binary_semaphore s(1);
+ std::atomic<int> a(0), b(0);
+ std::thread t([&] {
+ a.wait(0);
+ auto const dur = 250ms;
+ {
+ auto const at = std::chrono::system_clock::now() + dur;
+ VERIFY( !s.try_acquire_until(at) );
+
+ b++;
+ b.notify_one();
+ }
+
+ a.wait(1);
+ {
+ auto const at = std::chrono::system_clock::now() + dur;
+ VERIFY( s.try_acquire_until(at) );
+ }
+ b++;
+ b.notify_one();
+ });
+ t.detach();
+
+ s.acquire();
+ a++;
+ a.notify_one();
+ b.wait(0);
+ s.release();
+ a++;
+ a.notify_one();
+
+ b.wait(1);
+}
+#endif
+
+int main()
+{
+#ifdef _GLIBCXX_HAVE_POSIX_SEMAPHORE
+ test01();
+ test02();
+ test03();
+ test04();
+ test05();
+#endif
+}
diff --git a/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_until.cc
b/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_until.cc
new file mode 100644
index 00000000000..cc67c5c0bf0
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_until.cc
@@ -0,0 +1,94 @@
+// Copyright (C) 2019-2020 Free Software Foundation, Inc.
Just 2020.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+#include <semaphore>
+#include <chrono>
+#include <thread>
+#include <atomic>
+#include <testsuite_hooks.h>
+
+void test01()
+{
+ using namespace std::chrono_literals;
+ std::counting_semaphore<10> s(2);
+ s.acquire();
+
+ auto const dur = 250ms;
+ {
+ auto const at = std::chrono::system_clock::now() + dur;
+ auto const t0 = std::chrono::steady_clock::now();
+ VERIFY( s.try_acquire_until(at) );
+ auto const diff = std::chrono::steady_clock::now() - t0;
+ VERIFY( diff < dur );
+ }
+
+ {
+ auto const at = std::chrono::system_clock::now() + dur;
+ auto const t0 = std::chrono::steady_clock::now();
+ VERIFY( !s.try_acquire_until(at) );
+ auto const diff = std::chrono::steady_clock::now() - t0;
+ VERIFY( diff >= dur );
+ }
+}
+
+void test02()
+{
+ using namespace std::chrono_literals;
+ std::binary_semaphore s(1);
+ std::atomic<int> a(0), b(0);
+ std::thread t([&] {
+ a.wait(0);
+ auto const dur = 250ms;
+ {
+ auto const at = std::chrono::system_clock::now() + dur;
+ VERIFY( !s.try_acquire_until(at) );
+
+ b++;
+ b.notify_one();
+ }
+
+ a.wait(1);
+ {
+ auto const at = std::chrono::system_clock::now() + dur;
+ VERIFY( s.try_acquire_until(at) );
+ }
+ b++;
+ b.notify_one();
+ });
+ t.detach();
+
+ s.acquire();
+ a++;
+ a.notify_one();
+ b.wait(0);
+ s.release();
+ a++;
+ a.notify_one();
+
+ b.wait(1);
+}
+
+int main()
+{
+ test01();
+ test02();
+}
--
2.26.2
