[PATCH] Add c++2a binary_semaphore

[PATCH] Add c++2a binary_semaphore

[Thomas Rodgers]

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This patch adds the c++2a semaphore header and binary_semaphore type. The implementation is not complete, this patch is just to solicit initial feedback.

        * include/std/semaphore: New file.
	* include/std/version (__cpp_lib_semaphore): Add feature test macro.
	* include/Makefile.am (std_headers): add semaphore.
	* include/Makefile.in: Regenerate.
	* testsuite/30_threads/semaphore/1.cc: New test.
	* testsuite/30_threads/semaphore/2.cc: New test.
	* testsuite/30_threads/semaphore/binary_semaphore.cc: New test.
	* testsuite/30_threads/semaphore/try_acquire.cc: New test.
	* testsuite/30_threads/semaphore/try_acquire_for.cc: New test.
	* testsuite/30_threads/semaphore/try_acquire_until.cc: New test.


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From 8ce4252605361ed33b389a91fb7e3aeec529d9ac Mon Sep 17 00:00:00 2001
From: Thomas Rodgers <rodgert@thufir.appliantology.local>
Date: Mon, 17 Feb 2020 19:58:57 -0800
Subject: [PATCH] Add c++2a binary_semaphore

    * include/std/semaphore: New file.
    * include/std/version (__cpp_lib_semaphore): Add feature test macro.
    * include/Makefile.am (std_headers): add semaphore.
    * include/Makefile.in: Regenerate.
    * testsuite/30_threads/semaphore/1.cc: New test.
    * testsuite/30_threads/semaphore/2.cc: New test.
    * testsuite/30_threads/semaphore/binary_semaphore.cc: New test.
    * testsuite/30_threads/semaphore/try_acquire.cc: New test.
    * testsuite/30_threads/semaphore/try_acquire_for.cc: New test.
    * testsuite/30_threads/semaphore/try_acquire_until.cc: New test.
---
 libstdc++-v3/include/Makefile.am              |   1 +
 libstdc++-v3/include/Makefile.in              |   1 +
 libstdc++-v3/include/std/semaphore            | 131 ++++++++++++++++++
 libstdc++-v3/include/std/version              |   1 +
 .../testsuite/30_threads/semaphore/1.cc       |  27 ++++
 .../testsuite/30_threads/semaphore/2.cc       |  27 ++++
 .../30_threads/semaphore/binary_semaphore.cc  |  47 +++++++
 .../30_threads/semaphore/try_acquire.cc       |  36 +++++
 .../30_threads/semaphore/try_acquire_for.cc   |  72 ++++++++++
 .../30_threads/semaphore/try_acquire_until.cc |  74 ++++++++++
 10 files changed, 417 insertions(+)
 create mode 100644 libstdc++-v3/include/std/semaphore
 create mode 100644 libstdc++-v3/testsuite/30_threads/semaphore/1.cc
 create mode 100644 libstdc++-v3/testsuite/30_threads/semaphore/2.cc
 create mode 100644 libstdc++-v3/testsuite/30_threads/semaphore/binary_semaphore.cc
 create mode 100644 libstdc++-v3/testsuite/30_threads/semaphore/try_acquire.cc
 create mode 100644 libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_for.cc
 create mode 100644 libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_until.cc

diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
index 89835759069..2dbb7d3a6b1 100644
--- a/libstdc++-v3/include/Makefile.am
+++ b/libstdc++-v3/include/Makefile.am
@@ -69,6 +69,7 @@ std_headers = \
 	${std_srcdir}/ratio \
 	${std_srcdir}/regex \
 	${std_srcdir}/scoped_allocator \
+  ${std_srcdir}/semaphore \
 	${std_srcdir}/set \
 	${std_srcdir}/shared_mutex \
 	${std_srcdir}/span \
diff --git a/libstdc++-v3/include/Makefile.in b/libstdc++-v3/include/Makefile.in
index 123d24bb1c6..8f2780c86ce 100644
--- a/libstdc++-v3/include/Makefile.in
+++ b/libstdc++-v3/include/Makefile.in
@@ -414,6 +414,7 @@ std_headers = \
 	${std_srcdir}/ratio \
 	${std_srcdir}/regex \
 	${std_srcdir}/scoped_allocator \
+  ${std_srcdir}/semaphore \
 	${std_srcdir}/set \
 	${std_srcdir}/shared_mutex \
 	${std_srcdir}/span \
diff --git a/libstdc++-v3/include/std/semaphore b/libstdc++-v3/include/std/semaphore
new file mode 100644
index 00000000000..e3e88a50eec
--- /dev/null
+++ b/libstdc++-v3/include/std/semaphore
@@ -0,0 +1,131 @@
+// <stop_token> -*- C++ -*-
+
+// Copyright (C) 2019-2020 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/stop_token
+ *  This is a Standard C++ Library header.
+ */
+
+#ifndef _GLIBCXX_SEMAPHORE
+#define _GLIBCXX_SEMAPHORE
+
+#if __cplusplus > 201703L
+#define __cpp_lib_semaphore 201907L
+
+#include <cstddef>
+#include <atomic>
+#include <chrono>
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+  // TODO: replace this with a real implementation of std::binary_semaphore
+  struct binary_semaphore
+{
+  explicit binary_semaphore(int __d) : _M_counter(__d > 0) { }
+
+  static constexpr std::ptrdiff_t
+  max() noexcept
+  {
+   return 1;
+  }
+
+  void release() { _M_counter.fetch_add(1, memory_order::release); }
+
+  void acquire()
+  {
+   while (!_M_try_acquire())
+     {
+      _S_yield();
+     }
+  }
+
+  bool
+  try_acquire() noexcept
+  {
+   return _M_try_acquire(1u);
+  }
+
+  template<class _Rep, class _Period>
+  bool try_acquire_for(const std::chrono::duration<_Rep, _Period>& __rel_time)
+  {
+   auto __abst = std::chrono::steady_clock::now() + __rel_time;
+   return try_acquire_until(__abst);
+  }
+
+  template<class _Clock, class _Duration>
+  bool try_acquire_until(const std::chrono::time_point<_Clock, _Duration>& __abs_time)
+  {
+   do
+     {
+      if (_M_try_acquire())
+        {
+         return true;
+        }
+     } while (std::chrono::steady_clock::now() < __abs_time);
+   return false;
+  }
+
+private:
+  static void
+  _S_yield() noexcept
+  {
+#if defined __i386__ || defined __x86_64__
+   __builtin_ia32_pause();
+#elif defined _GLIBCXX_USE_SCHED_YIELD
+   __gthread_yield();
+#endif
+  }
+
+  bool
+  _M_try_acquire(unsigned __spin_ct)
+  {
+   int __old = 1;
+   while (!_M_counter.compare_exchange_weak(__old, 0,
+                                            memory_order::acquire,
+                                            memory_order::relaxed))
+     {
+       if (--__spin_ct == 0)
+         {
+           return false;
+         }
+      __old = 1;
+     }
+   return true;
+  }
+
+  static constexpr unsigned _S_spin_ct = 64u;
+  bool
+  _M_try_acquire()
+  {
+    return _M_try_acquire(1);
+  }
+
+  atomic<int> _M_counter;
+};
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace
+#endif // __cplusplus > 201703L
+#endif // _GLIBCXX_STOP_TOKEN
diff --git a/libstdc++-v3/include/std/version b/libstdc++-v3/include/std/version
index d8a97767453..4654830b614 100644
--- a/libstdc++-v3/include/std/version
+++ b/libstdc++-v3/include/std/version
@@ -188,6 +188,7 @@
 #define __cpp_lib_interpolate 201902L
 #ifdef _GLIBCXX_HAS_GTHREADS
 # define __cpp_lib_jthread 201907L
+# define __cpp_lib_semaphore 201907L
 #endif
 #define __cpp_lib_list_remove_return_type 201806L
 #define __cpp_lib_math_constants 201907L
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.
+//
+// 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/binary_semaphore.cc b/libstdc++-v3/testsuite/30_threads/semaphore/binary_semaphore.cc
new file mode 100644
index 00000000000..1a42d323ca0
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/binary_semaphore.cc
@@ -0,0 +1,47 @@
+// Copyright (C) 2019-2020 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 -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+#include <semaphore>
+#include <chrono>
+#include <thread>
+
+#include <testsuite_hooks.h>
+
+int main()
+{
+  std::binary_semaphore s(1);
+
+  auto ar = [&]() {
+              for(auto i = 0u; i < 512; ++i) {
+                s.acquire();
+                std::this_thread::sleep_for(std::chrono::microseconds(1));
+                s.release();
+              }
+            };
+
+  std::thread t(ar);
+  ar();
+
+  t.join();
+
+  return 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..295cfa9bca8
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire.cc
@@ -0,0 +1,36 @@
+// Copyright (C) 2019-2020 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 -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+#include <semaphore>
+
+int main()
+{
+  std::binary_semaphore s(1);
+
+  s.acquire();
+  if (s.try_acquire())
+    return -1;
+  s.release();
+  if (!s.try_acquire())
+    return -1;
+  return 0;
+}
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..a04b39b5401
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_for.cc
@@ -0,0 +1,72 @@
+// Copyright (C) 2019-2020 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 -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+#include <semaphore>
+#include <chrono>
+#include <thread>
+#include <mutex>
+#include <condition_variable>
+
+int main()
+{
+  using lock_type = std::unique_lock<std::mutex>;
+
+  bool ready = false;
+  lock_type::mutex_type m;
+  std::condition_variable cv;
+
+  std::binary_semaphore s(1);
+  auto ar =[&] {
+             s.acquire();
+             {
+               lock_type l(m);
+               ready = true;
+             }
+             cv.notify_one();
+             std::this_thread::sleep_for(std::chrono::milliseconds(500));
+             s.release();
+           };
+
+  std::thread t1(ar);
+  {
+    lock_type l(m, std::defer_lock);
+    cv.wait(l, [&] { return ready; });
+
+    if (s.try_acquire_for(std::chrono::milliseconds(100)))
+      return -1;
+    t1.join();
+    if (!s.try_acquire())
+      return -1;
+    s.release();
+    ready = false;
+  }
+
+  std::thread t2(ar);
+  {
+    lock_type l(m, std::defer_lock);
+    cv.wait(l, [&] { return ready; });
+    if (!s.try_acquire_for(std::chrono::milliseconds(1009)))
+      return -1;
+    t2.join();
+  }
+  return 0;
+}
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..987b655a6da
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_until.cc
@@ -0,0 +1,74 @@
+// Copyright (C) 2019-2020 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 -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+#include <semaphore>
+#include <chrono>
+#include <thread>
+#include <mutex>
+#include <condition_variable>
+
+int main()
+{
+  using lock_type = std::unique_lock<std::mutex>;
+
+  bool ready = false;
+  lock_type::mutex_type m;
+  std::condition_variable cv;
+
+  auto abst = std::chrono::steady_clock::now();
+
+  std::binary_semaphore s(1);
+  auto ar =[&] {
+             s.acquire();
+             {
+               lock_type l(m);
+               ready = true;
+             }
+             cv.notify_one();
+             std::this_thread::sleep_until(abst + std::chrono::milliseconds(500));
+             s.release();
+           };
+
+  std::thread t1(ar);
+  {
+    lock_type l(m, std::defer_lock);
+    cv.wait(l, [&] { return ready; });
+
+    if (s.try_acquire_until(abst + std::chrono::milliseconds(100)))
+      return -1;
+    t1.join();
+    if (!s.try_acquire())
+      return -1;
+    s.release();
+    ready = false;
+  }
+
+  std::thread t2(ar);
+  {
+    lock_type l(m, std::defer_lock);
+    cv.wait(l, [&] { return ready; });
+    if (!s.try_acquire_until(abst + std::chrono::milliseconds(1009)))
+      return -1;
+    t2.join();
+  }
+  return 0;
+}
-- 
2.24.1

Re: [PATCH] Add c++2a binary_semaphore

[Sebastian Huber]

Hello,

On 18/02/2020 07:46, Thomas Rodgers wrote:
> This patch adds the c++2a semaphore header and binary_semaphore type. The implementation is not complete, this patch is just to solicit initial feedback.

how do you plan to implement the binary semaphores? For example, do you 
want to add the binary semaphores to gthr.h or via a mutex and a 
condition variable or via some futex stuff? I ask because I would like 
to support this in RTEMS.

-- 
Sebastian Huber, embedded brains GmbH

Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone   : +49 89 189 47 41-16
Fax     : +49 89 189 47 41-09
E-Mail  : sebastian.huber@embedded-brains.de
PGP     : Public key available on request.

Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.

Re: [PATCH] Add c++2a binary_semaphore

[Jonathan Wakely]

On 18/02/20 14:48 +0100, Sebastian Huber wrote:
>Hello,
>
>On 18/02/2020 07:46, Thomas Rodgers wrote:
>>This patch adds the c++2a semaphore header and binary_semaphore type. The implementation is not complete, this patch is just to solicit initial feedback.
>
>how do you plan to implement the binary semaphores? For example, do 
>you want to add the binary semaphores to gthr.h or via a mutex and a 
>condition variable or via some futex stuff? I ask because I would like 
>to support this in RTEMS.

Futexes where possible.

Using POSIX semaphores might be a good alternative for the
std::counting_semaphore type, but for std::binary_semaphore we talked
about just using a spinlock based on std::atomic.

Re: [PATCH] Add c++2a binary_semaphore

[Sebastian Huber]

On 18/02/2020 15:30, Jonathan Wakely wrote:
> On 18/02/20 14:48 +0100, Sebastian Huber wrote:
>> Hello,
>>
>> On 18/02/2020 07:46, Thomas Rodgers wrote:
>>> This patch adds the c++2a semaphore header and binary_semaphore type. 
>>> The implementation is not complete, this patch is just to solicit 
>>> initial feedback.
>>
>> how do you plan to implement the binary semaphores? For example, do 
>> you want to add the binary semaphores to gthr.h or via a mutex and a 
>> condition variable or via some futex stuff? I ask because I would like 
>> to support this in RTEMS.
> 
> Futexes where possible.

It would be nice if this could be done through an extension of the 
gthr.h API similar to the condition variables (__GTHREAD_HAS_COND).

> Using POSIX semaphores might be a good alternative for the
> std::counting_semaphore type, 

Yes.

> but for std::binary_semaphore we talked
> about just using a spinlock based on std::atomic.

I would like to use the binary semaphores for task/interrupt 
synchronization. For this a blocking solution is required.

-- 
Sebastian Huber, embedded brains GmbH

Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone   : +49 89 189 47 41-16
Fax     : +49 89 189 47 41-09
E-Mail  : sebastian.huber@embedded-brains.de
PGP     : Public key available on request.

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Re: [PATCH] Add c++2a binary_semaphore

[Jonathan Wakely]

On 18/02/20 01:46 -0500, Thomas Rodgers wrote:
>This patch adds the c++2a semaphore header and binary_semaphore type. The implementation is not complete, this patch is just to solicit initial feedback.

Here is some initial feedback on comments and whitespace :-)

>diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
>index 89835759069..2dbb7d3a6b1 100644
>--- a/libstdc++-v3/include/Makefile.am
>+++ b/libstdc++-v3/include/Makefile.am
>@@ -69,6 +69,7 @@ std_headers = \
> 	${std_srcdir}/ratio \
> 	${std_srcdir}/regex \
> 	${std_srcdir}/scoped_allocator \
>+  ${std_srcdir}/semaphore \

Indentation is borked.

> 	${std_srcdir}/set \
> 	${std_srcdir}/shared_mutex \
> 	${std_srcdir}/span \
>diff --git a/libstdc++-v3/include/std/semaphore b/libstdc++-v3/include/std/semaphore
>new file mode 100644
>index 00000000000..e3e88a50eec
>--- /dev/null
>+++ b/libstdc++-v3/include/std/semaphore
>@@ -0,0 +1,131 @@
>+// <stop_token> -*- C++ -*-

Wrong header name in comment.

>+
>+// Copyright (C) 2019-2020 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/stop_token

Wrong name again.

>+ *  This is a Standard C++ Library header.
>+ */
>+
>+#ifndef _GLIBCXX_SEMAPHORE
>+#define _GLIBCXX_SEMAPHORE
>+
>+#if __cplusplus > 201703L
>+#define __cpp_lib_semaphore 201907L

We shouldn't define this until the file is complete, i.e. when it
provides binary_semaphore and counting_semaphore.

>+
>+#include <cstddef>

Is this header needed? ptrdiff_t and size_t are both defined in
<bits/c++config.h> which every header already includes.

>+#include <atomic>
>+#include <chrono>
>+
>+namespace std _GLIBCXX_VISIBILITY(default)
>+{
>+_GLIBCXX_BEGIN_NAMESPACE_VERSION
>+
>+  // TODO: replace this with a real implementation of std::binary_semaphore
>+  struct binary_semaphore
>+{

Indentation is borked here too.

>+  explicit binary_semaphore(int __d) : _M_counter(__d > 0) { }
>+
>+  static constexpr std::ptrdiff_t
>+  max() noexcept
>+  {
>+   return 1;
>+  }
>+
>+  void release() { _M_counter.fetch_add(1, memory_order::release); }
>+
>+  void acquire()
>+  {
>+   while (!_M_try_acquire())
>+     {
>+      _S_yield();
>+     }
>+  }
>+
>+  bool
>+  try_acquire() noexcept
>+  {
>+   return _M_try_acquire(1u);
>+  }
>+
>+  template<class _Rep, class _Period>
>+  bool try_acquire_for(const std::chrono::duration<_Rep, _Period>& __rel_time)
>+  {
>+   auto __abst = std::chrono::steady_clock::now() + __rel_time;
>+   return try_acquire_until(__abst);
>+  }
>+
>+  template<class _Clock, class _Duration>
>+  bool try_acquire_until(const std::chrono::time_point<_Clock, _Duration>& __abs_time)
>+  {
>+   do
>+     {
>+      if (_M_try_acquire())
>+        {
>+         return true;
>+        }
>+     } while (std::chrono::steady_clock::now() < __abs_time);
>+   return false;
>+  }
>+
>+private:
>+  static void
>+  _S_yield() noexcept
>+  {
>+#if defined __i386__ || defined __x86_64__
>+   __builtin_ia32_pause();
>+#elif defined _GLIBCXX_USE_SCHED_YIELD
>+   __gthread_yield();
>+#endif
>+  }
>+
>+  bool
>+  _M_try_acquire(unsigned __spin_ct)
>+  {
>+   int __old = 1;
>+   while (!_M_counter.compare_exchange_weak(__old, 0,
>+                                            memory_order::acquire,
>+                                            memory_order::relaxed))
>+     {
>+       if (--__spin_ct == 0)
>+         {
>+           return false;
>+         }
>+      __old = 1;
>+     }
>+   return true;
>+  }
>+
>+  static constexpr unsigned _S_spin_ct = 64u;
>+  bool
>+  _M_try_acquire()
>+  {
>+    return _M_try_acquire(1);
>+  }
>+
>+  atomic<int> _M_counter;
>+};
>+
>+_GLIBCXX_END_NAMESPACE_VERSION
>+} // namespace
>+#endif // __cplusplus > 201703L
>+#endif // _GLIBCXX_STOP_TOKEN

Wrong macro name in comment.

Re: [PATCH] Add c++2a binary_semaphore

[Thomas Rodgers]

[-- Attachment #1: Type: text/plain, Size: 5674 bytes --]

Should address the previous issues, adds backoff logic.

    * include/std/semaphore: New file.
    * include/std/version (__cpp_lib_semaphore): Add feature test macro.
    * include/Makefile.am (std_headers): add semaphore.
    * include/Makefile.in: Regenerate.
    * testsuite/30_threads/semaphore/1.cc: New test.
    * testsuite/30_threads/semaphore/2.cc: New test.
    * testsuite/30_threads/semaphore/binary_semaphore.cc: New test.
    * testsuite/30_threads/semaphore/try_acquire.cc: New test.
    * testsuite/30_threads/semaphore/try_acquire_for.cc: New test.
    * testsuite/30_threads/semaphore/try_acquire_until.cc: New test.

----- Original Message -----
From: "Jonathan Wakely" <jwakely@redhat.com>
To: "Thomas Rodgers" <trodgers@redhat.com>
Cc: gcc-patches@gcc.gnu.org, libstdc++@gcc.gnu.org
Sent: Tuesday, February 18, 2020 6:25:41 AM
Subject: Re: [PATCH] Add c++2a binary_semaphore

On 18/02/20 01:46 -0500, Thomas Rodgers wrote:
>This patch adds the c++2a semaphore header and binary_semaphore type. The implementation is not complete, this patch is just to solicit initial feedback.

Here is some initial feedback on comments and whitespace :-)

>diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
>index 89835759069..2dbb7d3a6b1 100644
>--- a/libstdc++-v3/include/Makefile.am
>+++ b/libstdc++-v3/include/Makefile.am
>@@ -69,6 +69,7 @@ std_headers = \
> 	${std_srcdir}/ratio \
> 	${std_srcdir}/regex \
> 	${std_srcdir}/scoped_allocator \
>+  ${std_srcdir}/semaphore \

Indentation is borked.

> 	${std_srcdir}/set \
> 	${std_srcdir}/shared_mutex \
> 	${std_srcdir}/span \
>diff --git a/libstdc++-v3/include/std/semaphore b/libstdc++-v3/include/std/semaphore
>new file mode 100644
>index 00000000000..e3e88a50eec
>--- /dev/null
>+++ b/libstdc++-v3/include/std/semaphore
>@@ -0,0 +1,131 @@
>+// <stop_token> -*- C++ -*-

Wrong header name in comment.

>+
>+// Copyright (C) 2019-2020 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/stop_token

Wrong name again.

>+ *  This is a Standard C++ Library header.
>+ */
>+
>+#ifndef _GLIBCXX_SEMAPHORE
>+#define _GLIBCXX_SEMAPHORE
>+
>+#if __cplusplus > 201703L
>+#define __cpp_lib_semaphore 201907L

We shouldn't define this until the file is complete, i.e. when it
provides binary_semaphore and counting_semaphore.

>+
>+#include <cstddef>

Is this header needed? ptrdiff_t and size_t are both defined in
<bits/c++config.h> which every header already includes.

>+#include <atomic>
>+#include <chrono>
>+
>+namespace std _GLIBCXX_VISIBILITY(default)
>+{
>+_GLIBCXX_BEGIN_NAMESPACE_VERSION
>+
>+  // TODO: replace this with a real implementation of std::binary_semaphore
>+  struct binary_semaphore
>+{

Indentation is borked here too.

>+  explicit binary_semaphore(int __d) : _M_counter(__d > 0) { }
>+
>+  static constexpr std::ptrdiff_t
>+  max() noexcept
>+  {
>+   return 1;
>+  }
>+
>+  void release() { _M_counter.fetch_add(1, memory_order::release); }
>+
>+  void acquire()
>+  {
>+   while (!_M_try_acquire())
>+     {
>+      _S_yield();
>+     }
>+  }
>+
>+  bool
>+  try_acquire() noexcept
>+  {
>+   return _M_try_acquire(1u);
>+  }
>+
>+  template<class _Rep, class _Period>
>+  bool try_acquire_for(const std::chrono::duration<_Rep, _Period>& __rel_time)
>+  {
>+   auto __abst = std::chrono::steady_clock::now() + __rel_time;
>+   return try_acquire_until(__abst);
>+  }
>+
>+  template<class _Clock, class _Duration>
>+  bool try_acquire_until(const std::chrono::time_point<_Clock, _Duration>& __abs_time)
>+  {
>+   do
>+     {
>+      if (_M_try_acquire())
>+        {
>+         return true;
>+        }
>+     } while (std::chrono::steady_clock::now() < __abs_time);
>+   return false;
>+  }
>+
>+private:
>+  static void
>+  _S_yield() noexcept
>+  {
>+#if defined __i386__ || defined __x86_64__
>+   __builtin_ia32_pause();
>+#elif defined _GLIBCXX_USE_SCHED_YIELD
>+   __gthread_yield();
>+#endif
>+  }
>+
>+  bool
>+  _M_try_acquire(unsigned __spin_ct)
>+  {
>+   int __old = 1;
>+   while (!_M_counter.compare_exchange_weak(__old, 0,
>+                                            memory_order::acquire,
>+                                            memory_order::relaxed))
>+     {
>+       if (--__spin_ct == 0)
>+         {
>+           return false;
>+         }
>+      __old = 1;
>+     }
>+   return true;
>+  }
>+
>+  static constexpr unsigned _S_spin_ct = 64u;
>+  bool
>+  _M_try_acquire()
>+  {
>+    return _M_try_acquire(1);
>+  }
>+
>+  atomic<int> _M_counter;
>+};
>+
>+_GLIBCXX_END_NAMESPACE_VERSION
>+} // namespace
>+#endif // __cplusplus > 201703L
>+#endif // _GLIBCXX_STOP_TOKEN

Wrong macro name in comment.


[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: 0001-Add-c-2a-binary_semaphore.patch --]
[-- Type: text/x-patch; name=0001-Add-c-2a-binary_semaphore.patch, Size: 145577 bytes --]

From 03133adcadc7931300de88ffda52f8066c2a6591 Mon Sep 17 00:00:00 2001
From: Thomas Rodgers <rodgert@thufir.appliantology.local>
Date: Mon, 17 Feb 2020 19:58:57 -0800
Subject: [PATCH] Add c++2a binary_semaphore

    * include/std/semaphore: New file.
    * include/std/version (__cpp_lib_semaphore): Add feature test macro.
    * include/Makefile.am (std_headers): add semaphore.
    * include/Makefile.in: Regenerate.
    * testsuite/30_threads/semaphore/1.cc: New test.
    * testsuite/30_threads/semaphore/2.cc: New test.
    * testsuite/30_threads/semaphore/binary_semaphore.cc: New test.
    * testsuite/30_threads/semaphore/try_acquire.cc: New test.
    * testsuite/30_threads/semaphore/try_acquire_for.cc: New test.
    * testsuite/30_threads/semaphore/try_acquire_until.cc: New test.
---
 libstdc++-v3/Makefile.am                      | 1513 +++++++++++++++++
 libstdc++-v3/Makefile.in                      | 1477 +++++++++++++++-
 libstdc++-v3/include/Makefile.am              |    1 +
 libstdc++-v3/include/Makefile.in              |    1 +
 libstdc++-v3/include/std/semaphore            |  245 +++
 libstdc++-v3/include/std/version              |    2 +
 .../testsuite/30_threads/semaphore/1.cc       |   27 +
 .../testsuite/30_threads/semaphore/2.cc       |   27 +
 .../30_threads/semaphore/binary_semaphore.cc  |   47 +
 .../30_threads/semaphore/try_acquire.cc       |   36 +
 .../30_threads/semaphore/try_acquire_for.cc   |   72 +
 .../30_threads/semaphore/try_acquire_until.cc |   74 +
 12 files changed, 3511 insertions(+), 11 deletions(-)
 create mode 100644 libstdc++-v3/include/std/semaphore
 create mode 100644 libstdc++-v3/testsuite/30_threads/semaphore/1.cc
 create mode 100644 libstdc++-v3/testsuite/30_threads/semaphore/2.cc
 create mode 100644 libstdc++-v3/testsuite/30_threads/semaphore/binary_semaphore.cc
 create mode 100644 libstdc++-v3/testsuite/30_threads/semaphore/try_acquire.cc
 create mode 100644 libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_for.cc
 create mode 100644 libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_until.cc

diff --git a/libstdc++-v3/Makefile.am b/libstdc++-v3/Makefile.am
index da021ec7074..85aaaa7a47d 100644
--- a/libstdc++-v3/Makefile.am
+++ b/libstdc++-v3/Makefile.am
@@ -17,6 +17,1519 @@
 ## GNU General Public License for more details.
 
 ## You should have received a copy of the GNU General Public License along
+## Makefile for the include subdirectory of the GNU C++ Standard library.
+##
+## Copyright (C) 2001-2020 Free Software Foundation, Inc.
+##
+## This file is part of the libstdc++ version 3 distribution.
+## Process this file with automake to produce Makefile.in.
+
+## 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 $(top_srcdir)/fragment.am
+
+# Standard C++ includes.
+std_srcdir = ${glibcxx_srcdir}/include/std
+std_builddir = .
+std_headers = \
+	${std_srcdir}/algorithm \
+	${std_srcdir}/any \
+	${std_srcdir}/array \
+	${std_srcdir}/atomic \
+	${std_srcdir}/bit \
+	${std_srcdir}/bitset \
+	${std_srcdir}/charconv \
+	${std_srcdir}/chrono \
+	${std_srcdir}/codecvt \
+	${std_srcdir}/complex \
+	${std_srcdir}/concepts \
+	${std_srcdir}/condition_variable \
+	${std_srcdir}/coroutine \
+	${std_srcdir}/deque \
+	${std_srcdir}/execution \
+	${std_srcdir}/filesystem \
+	${std_srcdir}/forward_list \
+	${std_srcdir}/fstream \
+	${std_srcdir}/functional \
+	${std_srcdir}/future \
+	${std_srcdir}/iomanip \
+	${std_srcdir}/ios \
+	${std_srcdir}/iosfwd \
+	${std_srcdir}/iostream \
+	${std_srcdir}/istream \
+	${std_srcdir}/iterator \
+	${std_srcdir}/limits \
+	${std_srcdir}/list \
+	${std_srcdir}/locale \
+	${std_srcdir}/map \
+	${std_srcdir}/memory \
+	${std_srcdir}/memory_resource \
+	${std_srcdir}/mutex \
+	${std_srcdir}/numbers \
+	${std_srcdir}/numeric \
+	${std_srcdir}/optional \
+	${std_srcdir}/ostream \
+	${std_srcdir}/queue \
+	${std_srcdir}/random \
+	${std_srcdir}/ranges \
+	${std_srcdir}/ratio \
+	${std_srcdir}/regex \
+	${std_srcdir}/scoped_allocator \
+  ${std_srcdir}/semaphore \
+	${std_srcdir}/set \
+	${std_srcdir}/shared_mutex \
+	${std_srcdir}/span \
+	${std_srcdir}/sstream \
+	${std_srcdir}/stack \
+	${std_srcdir}/stdexcept \
+	${std_srcdir}/stop_token \
+	${std_srcdir}/streambuf \
+	${std_srcdir}/string \
+	${std_srcdir}/string_view \
+	${std_srcdir}/system_error \
+	${std_srcdir}/thread \
+	${std_srcdir}/tuple \
+	${std_srcdir}/typeindex \
+	${std_srcdir}/type_traits \
+	${std_srcdir}/unordered_map \
+	${std_srcdir}/unordered_set \
+	${std_srcdir}/utility \
+	${std_srcdir}/valarray \
+	${std_srcdir}/variant \
+	${std_srcdir}/vector \
+	${std_srcdir}/version
+
+bits_srcdir = ${glibcxx_srcdir}/include/bits
+bits_builddir = ./bits
+bits_headers = \
+	${bits_srcdir}/algorithmfwd.h \
+	${bits_srcdir}/alloc_traits.h \
+	${bits_srcdir}/allocated_ptr.h \
+	${bits_srcdir}/allocator.h \
+	${bits_srcdir}/atomic_base.h \
+	${bits_srcdir}/atomic_futex.h \
+	${bits_srcdir}/basic_ios.h \
+	${bits_srcdir}/basic_ios.tcc \
+	${bits_srcdir}/basic_string.h \
+	${bits_srcdir}/basic_string.tcc \
+	${bits_srcdir}/boost_concept_check.h \
+	${bits_srcdir}/c++0x_warning.h \
+	${bits_srcdir}/char_traits.h \
+	${bits_srcdir}/charconv.h \
+	${bits_srcdir}/codecvt.h \
+	${bits_srcdir}/concept_check.h \
+	${bits_srcdir}/cpp_type_traits.h \
+	${bits_srcdir}/deque.tcc \
+	${bits_srcdir}/enable_special_members.h \
+	${bits_srcdir}/erase_if.h \
+	${bits_srcdir}/forward_list.h \
+	${bits_srcdir}/forward_list.tcc \
+	${bits_srcdir}/fs_dir.h \
+	${bits_srcdir}/fs_fwd.h \
+	${bits_srcdir}/fs_ops.h \
+	${bits_srcdir}/fs_path.h \
+	${bits_srcdir}/fstream.tcc \
+	${bits_srcdir}/functexcept.h \
+	${bits_srcdir}/functional_hash.h \
+	${bits_srcdir}/gslice.h \
+	${bits_srcdir}/gslice_array.h \
+	${bits_srcdir}/hashtable.h \
+	${bits_srcdir}/hashtable_policy.h \
+	${bits_srcdir}/indirect_array.h \
+	${bits_srcdir}/invoke.h \
+	${bits_srcdir}/ios_base.h \
+	${bits_srcdir}/istream.tcc \
+	${bits_srcdir}/iterator_concepts.h \
+	${bits_srcdir}/list.tcc \
+	${bits_srcdir}/locale_classes.h \
+	${bits_srcdir}/locale_classes.tcc \
+	${bits_srcdir}/locale_conv.h \
+	${bits_srcdir}/locale_facets.h \
+	${bits_srcdir}/locale_facets.tcc \
+	${bits_srcdir}/locale_facets_nonio.h \
+	${bits_srcdir}/locale_facets_nonio.tcc \
+	${bits_srcdir}/localefwd.h \
+	${bits_srcdir}/mask_array.h \
+	${bits_srcdir}/memoryfwd.h \
+	${bits_srcdir}/move.h \
+	${bits_srcdir}/node_handle.h \
+	${bits_srcdir}/ostream.tcc \
+	${bits_srcdir}/ostream_insert.h \
+	${bits_srcdir}/parse_numbers.h \
+	${bits_srcdir}/postypes.h \
+	${bits_srcdir}/predefined_ops.h \
+	${bits_srcdir}/ptr_traits.h \
+	${bits_srcdir}/quoted_string.h \
+	${bits_srcdir}/random.h \
+	${bits_srcdir}/random.tcc \
+	${bits_srcdir}/range_access.h \
+	${bits_srcdir}/range_cmp.h \
+	${bits_srcdir}/refwrap.h \
+	${bits_srcdir}/regex.h \
+	${bits_srcdir}/regex.tcc \
+	${bits_srcdir}/regex_constants.h \
+	${bits_srcdir}/regex_error.h \
+	${bits_srcdir}/regex_scanner.h \
+	${bits_srcdir}/regex_scanner.tcc \
+	${bits_srcdir}/regex_automaton.h \
+	${bits_srcdir}/regex_automaton.tcc \
+	${bits_srcdir}/regex_compiler.h \
+	${bits_srcdir}/regex_compiler.tcc \
+	${bits_srcdir}/regex_executor.h \
+	${bits_srcdir}/regex_executor.tcc \
+	${bits_srcdir}/shared_ptr.h \
+	${bits_srcdir}/shared_ptr_atomic.h \
+	${bits_srcdir}/shared_ptr_base.h \
+	${bits_srcdir}/slice_array.h \
+	${bits_srcdir}/specfun.h \
+	${bits_srcdir}/sstream.tcc \
+	${bits_srcdir}/std_abs.h \
+	${bits_srcdir}/std_function.h \
+	${bits_srcdir}/std_mutex.h \
+	${bits_srcdir}/stl_algo.h \
+	${bits_srcdir}/stl_algobase.h \
+	${bits_srcdir}/stl_bvector.h \
+	${bits_srcdir}/stl_construct.h \
+	${bits_srcdir}/stl_deque.h \
+	${bits_srcdir}/stl_function.h \
+	${bits_srcdir}/stl_heap.h \
+	${bits_srcdir}/stl_iterator.h \
+	${bits_srcdir}/stl_iterator_base_funcs.h \
+	${bits_srcdir}/stl_iterator_base_types.h \
+	${bits_srcdir}/stl_list.h \
+	${bits_srcdir}/stl_map.h \
+	${bits_srcdir}/stl_multimap.h \
+	${bits_srcdir}/stl_multiset.h \
+	${bits_srcdir}/stl_numeric.h \
+	${bits_srcdir}/stl_pair.h \
+	${bits_srcdir}/stl_queue.h \
+	${bits_srcdir}/stl_raw_storage_iter.h \
+	${bits_srcdir}/stl_relops.h \
+	${bits_srcdir}/stl_set.h \
+	${bits_srcdir}/stl_stack.h \
+	${bits_srcdir}/stl_tempbuf.h \
+	${bits_srcdir}/stl_tree.h \
+	${bits_srcdir}/stl_uninitialized.h \
+	${bits_srcdir}/stl_vector.h \
+	${bits_srcdir}/stream_iterator.h \
+	${bits_srcdir}/streambuf_iterator.h \
+	${bits_srcdir}/streambuf.tcc \
+	${bits_srcdir}/stringfwd.h \
+	${bits_srcdir}/string_view.tcc \
+	${bits_srcdir}/uniform_int_dist.h \
+	${bits_srcdir}/unique_lock.h \
+	${bits_srcdir}/unique_ptr.h \
+	${bits_srcdir}/unordered_map.h \
+	${bits_srcdir}/unordered_set.h \
+	${bits_srcdir}/uses_allocator.h \
+	${bits_srcdir}/valarray_array.h \
+	${bits_srcdir}/valarray_array.tcc \
+	${bits_srcdir}/valarray_before.h \
+	${bits_srcdir}/valarray_after.h \
+	${bits_srcdir}/vector.tcc
+
+bits_host_headers = \
+	${glibcxx_srcdir}/${CPU_OPT_BITS_RANDOM}
+
+bits_sup_srcdir = ${glibcxx_srcdir}/libsupc++
+bits_sup_headers = \
+	${bits_sup_srcdir}/atomic_lockfree_defines.h \
+	${bits_sup_srcdir}/cxxabi_forced.h \
+	${bits_sup_srcdir}/cxxabi_init_exception.h \
+	${bits_sup_srcdir}/exception.h \
+	${bits_sup_srcdir}/exception_defines.h \
+	${bits_sup_srcdir}/exception_ptr.h \
+	${bits_sup_srcdir}/hash_bytes.h \
+	${bits_sup_srcdir}/nested_exception.h
+
+# C++17 Parallel Algorithm Includes.
+pstl_srcdir = ${glibcxx_srcdir}/include/pstl
+pstl_builddir = ./pstl
+pstl_headers = \
+	${pstl_srcdir}/algorithm_fwd.h \
+	${pstl_srcdir}/algorithm_impl.h \
+	${pstl_srcdir}/execution_defs.h \
+	${pstl_srcdir}/execution_impl.h \
+	${pstl_srcdir}/glue_algorithm_defs.h \
+	${pstl_srcdir}/glue_algorithm_impl.h \
+	${pstl_srcdir}/glue_execution_defs.h \
+	${pstl_srcdir}/glue_memory_defs.h \
+	${pstl_srcdir}/glue_memory_impl.h \
+	${pstl_srcdir}/glue_numeric_defs.h \
+	${pstl_srcdir}/glue_numeric_impl.h \
+	${pstl_srcdir}/memory_impl.h \
+	${pstl_srcdir}/numeric_fwd.h \
+	${pstl_srcdir}/numeric_impl.h \
+	${pstl_srcdir}/parallel_backend.h \
+	${pstl_srcdir}/parallel_backend_tbb.h \
+	${pstl_srcdir}/parallel_backend_serial.h \
+	${pstl_srcdir}/parallel_backend_utils.h \
+	${pstl_srcdir}/parallel_impl.h \
+	${pstl_srcdir}/pstl_config.h \
+	${pstl_srcdir}/unseq_backend_simd.h \
+	${pstl_srcdir}/utils.h
+
+backward_srcdir = ${glibcxx_srcdir}/include/backward
+backward_builddir = ./backward
+backward_headers = \
+	${backward_srcdir}/auto_ptr.h \
+	${backward_srcdir}/backward_warning.h \
+	${backward_srcdir}/binders.h \
+	${backward_srcdir}/hash_map \
+	${backward_srcdir}/hash_set \
+	${backward_srcdir}/hash_fun.h \
+	${backward_srcdir}/hashtable.h \
+	${backward_srcdir}/strstream
+
+pb_srcdir = ${glibcxx_srcdir}/include/ext/pb_ds
+pb_builddir = ./ext/pb_ds
+
+pb_subdirs = \
+	${pb_builddir}/detail \
+	${pb_builddir}/detail/pairing_heap_ \
+	${pb_builddir}/detail/splay_tree_ \
+	${pb_builddir}/detail/list_update_map_ \
+	${pb_builddir}/detail/branch_policy \
+	${pb_builddir}/detail/trie_policy \
+	${pb_builddir}/detail/gp_hash_table_map_ \
+	${pb_builddir}/detail/tree_policy \
+	${pb_builddir}/detail/binomial_heap_base_ \
+	${pb_builddir}/detail/resize_policy \
+	${pb_builddir}/detail/bin_search_tree_ \
+	${pb_builddir}/detail/binomial_heap_ \
+	${pb_builddir}/detail/thin_heap_ \
+	${pb_builddir}/detail/pat_trie_ \
+	${pb_builddir}/detail/cc_hash_table_map_ \
+	${pb_builddir}/detail/rc_binomial_heap_ \
+	${pb_builddir}/detail/left_child_next_sibling_heap_ \
+	${pb_builddir}/detail/unordered_iterator \
+	${pb_builddir}/detail/binary_heap_ \
+	${pb_builddir}/detail/ov_tree_map_ \
+	${pb_builddir}/detail/hash_fn \
+	${pb_builddir}/detail/eq_fn \
+	${pb_builddir}/detail/rb_tree_map_ \
+	${pb_builddir}/detail/list_update_policy
+
+# The ability for make and the underlying host to deal with this
+# unwieldy list as one entire entity is not a sure thing, and may
+# cause build errors. Thus, split one list into many smaller
+# mini-lists, with the maximum size per mini-list of no more than 42.
+
+pb_headers1 = \
+	${pb_srcdir}/assoc_container.hpp \
+	${pb_srcdir}/exception.hpp \
+	${pb_srcdir}/hash_policy.hpp \
+	${pb_srcdir}/list_update_policy.hpp \
+	${pb_srcdir}/priority_queue.hpp \
+	${pb_srcdir}/tag_and_trait.hpp \
+	${pb_srcdir}/tree_policy.hpp \
+	${pb_srcdir}/trie_policy.hpp \
+	${pb_srcdir}/detail/branch_policy/branch_policy.hpp \
+	${pb_srcdir}/detail/branch_policy/null_node_metadata.hpp \
+	${pb_srcdir}/detail/branch_policy/traits.hpp \
+	${pb_srcdir}/detail/binary_heap_/binary_heap_.hpp \
+	${pb_srcdir}/detail/binary_heap_/const_iterator.hpp \
+	${pb_srcdir}/detail/binary_heap_/point_const_iterator.hpp \
+	${pb_srcdir}/detail/binary_heap_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/binary_heap_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/binary_heap_/entry_cmp.hpp \
+	${pb_srcdir}/detail/binary_heap_/entry_pred.hpp \
+	${pb_srcdir}/detail/binary_heap_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/binary_heap_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/binary_heap_/info_fn_imps.hpp \
+	${pb_srcdir}/detail/binary_heap_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/binary_heap_/iterators_fn_imps.hpp \
+	${pb_srcdir}/detail/binary_heap_/policy_access_fn_imps.hpp \
+	${pb_srcdir}/detail/binary_heap_/resize_policy.hpp \
+	${pb_srcdir}/detail/binary_heap_/split_join_fn_imps.hpp \
+	${pb_srcdir}/detail/binary_heap_/trace_fn_imps.hpp \
+	${pb_srcdir}/detail/binomial_heap_base_/binomial_heap_base_.hpp \
+	${pb_srcdir}/detail/binomial_heap_base_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/binomial_heap_base_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/binomial_heap_base_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/binomial_heap_base_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/binomial_heap_base_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/binomial_heap_base_/split_join_fn_imps.hpp \
+	${pb_srcdir}/detail/binomial_heap_/binomial_heap_.hpp \
+	${pb_srcdir}/detail/binomial_heap_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/binomial_heap_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/bin_search_tree_.hpp
+
+pb_headers2 = \
+	${pb_srcdir}/detail/bin_search_tree_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/info_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/iterators_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/node_iterators.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/point_iterators.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/policy_access_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/r_erase_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/rotate_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/split_join_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/traits.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/cc_ht_map_.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/cmp_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/cond_key_dtor_entry_dealtor.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/constructor_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/constructor_destructor_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/constructor_destructor_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/debug_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/debug_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/entry_list_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/erase_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/erase_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/find_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/info_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/insert_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/insert_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/iterators_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/policy_access_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/resize_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/resize_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/resize_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/size_fn_imps.hpp
+
+pb_headers3 = \
+	${pb_srcdir}/detail/cc_hash_table_map_/trace_fn_imps.hpp \
+	${pb_srcdir}/detail/cond_dealtor.hpp \
+	${pb_srcdir}/detail/container_base_dispatch.hpp \
+	${pb_srcdir}/detail/eq_fn/eq_by_less.hpp \
+	${pb_srcdir}/detail/eq_fn/hash_eq_fn.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/constructor_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/constructor_destructor_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/constructor_destructor_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/debug_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/debug_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/erase_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/erase_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/find_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/find_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/gp_ht_map_.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/info_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/insert_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/insert_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/iterator_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/policy_access_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/resize_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/resize_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/resize_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/trace_fn_imps.hpp \
+	${pb_srcdir}/detail/hash_fn/direct_mask_range_hashing_imp.hpp \
+	${pb_srcdir}/detail/hash_fn/direct_mod_range_hashing_imp.hpp \
+	${pb_srcdir}/detail/hash_fn/linear_probe_fn_imp.hpp \
+	${pb_srcdir}/detail/hash_fn/mask_based_range_hashing.hpp \
+	${pb_srcdir}/detail/hash_fn/mod_based_range_hashing.hpp \
+	${pb_srcdir}/detail/hash_fn/probe_fn_base.hpp \
+	${pb_srcdir}/detail/hash_fn/quadratic_probe_fn_imp.hpp \
+	${pb_srcdir}/detail/hash_fn/ranged_hash_fn.hpp \
+	${pb_srcdir}/detail/hash_fn/ranged_probe_fn.hpp
+
+pb_headers4 = \
+	${pb_srcdir}/detail/hash_fn/sample_probe_fn.hpp \
+	${pb_srcdir}/detail/hash_fn/sample_ranged_hash_fn.hpp \
+	${pb_srcdir}/detail/hash_fn/sample_ranged_probe_fn.hpp \
+	${pb_srcdir}/detail/hash_fn/sample_range_hashing.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/const_iterator.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/point_const_iterator.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/info_fn_imps.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/iterators_fn_imps.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/left_child_next_sibling_heap_.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/node.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/policy_access_fn_imps.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/trace_fn_imps.hpp \
+	${pb_srcdir}/detail/list_update_map_/constructor_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/list_update_map_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/list_update_map_/entry_metadata_base.hpp \
+	${pb_srcdir}/detail/list_update_map_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/list_update_map_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/list_update_map_/info_fn_imps.hpp \
+	${pb_srcdir}/detail/list_update_map_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/list_update_map_/iterators_fn_imps.hpp \
+	${pb_srcdir}/detail/list_update_map_/lu_map_.hpp \
+	${pb_srcdir}/detail/list_update_map_/trace_fn_imps.hpp \
+	${pb_srcdir}/detail/list_update_policy/lu_counter_metadata.hpp \
+	${pb_srcdir}/detail/list_update_policy/sample_update_policy.hpp \
+	${pb_srcdir}/detail/debug_map_base.hpp \
+	${pb_srcdir}/detail/ov_tree_map_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/ov_tree_map_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/ov_tree_map_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/ov_tree_map_/info_fn_imps.hpp \
+	${pb_srcdir}/detail/ov_tree_map_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/ov_tree_map_/iterators_fn_imps.hpp \
+	${pb_srcdir}/detail/ov_tree_map_/node_iterators.hpp \
+	${pb_srcdir}/detail/ov_tree_map_/ov_tree_map_.hpp
+
+pb_headers5 = \
+	${pb_srcdir}/detail/ov_tree_map_/policy_access_fn_imps.hpp \
+	${pb_srcdir}/detail/ov_tree_map_/split_join_fn_imps.hpp \
+	${pb_srcdir}/detail/ov_tree_map_/traits.hpp \
+	${pb_srcdir}/detail/pairing_heap_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/pairing_heap_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/pairing_heap_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/pairing_heap_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/pairing_heap_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/pairing_heap_/pairing_heap_.hpp \
+	${pb_srcdir}/detail/pairing_heap_/split_join_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/info_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/insert_join_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/iterators_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/pat_trie_.hpp \
+	${pb_srcdir}/detail/pat_trie_/pat_trie_base.hpp \
+	${pb_srcdir}/detail/pat_trie_/policy_access_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/r_erase_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/rotate_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/split_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/synth_access_traits.hpp \
+	${pb_srcdir}/detail/pat_trie_/trace_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/traits.hpp \
+	${pb_srcdir}/detail/pat_trie_/update_fn_imps.hpp \
+	${pb_srcdir}/detail/priority_queue_base_dispatch.hpp \
+	${pb_srcdir}/detail/rb_tree_map_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/rb_tree_map_/debug_fn_imps.hpp
+
+pb_headers6 = \
+	${pb_srcdir}/detail/rb_tree_map_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/rb_tree_map_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/rb_tree_map_/info_fn_imps.hpp \
+	${pb_srcdir}/detail/rb_tree_map_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/rb_tree_map_/node.hpp \
+	${pb_srcdir}/detail/rb_tree_map_/rb_tree_.hpp \
+	${pb_srcdir}/detail/rb_tree_map_/split_join_fn_imps.hpp \
+	${pb_srcdir}/detail/rb_tree_map_/traits.hpp \
+	${pb_srcdir}/detail/rc_binomial_heap_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/rc_binomial_heap_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/rc_binomial_heap_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/rc_binomial_heap_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/rc_binomial_heap_/rc_binomial_heap_.hpp \
+	${pb_srcdir}/detail/rc_binomial_heap_/rc.hpp \
+	${pb_srcdir}/detail/rc_binomial_heap_/split_join_fn_imps.hpp \
+	${pb_srcdir}/detail/rc_binomial_heap_/trace_fn_imps.hpp \
+	${pb_srcdir}/detail/resize_policy/cc_hash_max_collision_check_resize_trigger_imp.hpp \
+	${pb_srcdir}/detail/resize_policy/hash_exponential_size_policy_imp.hpp \
+	${pb_srcdir}/detail/resize_policy/hash_load_check_resize_trigger_imp.hpp \
+	${pb_srcdir}/detail/resize_policy/hash_load_check_resize_trigger_size_base.hpp \
+	${pb_srcdir}/detail/resize_policy/hash_prime_size_policy_imp.hpp \
+	${pb_srcdir}/detail/resize_policy/hash_standard_resize_policy_imp.hpp \
+	${pb_srcdir}/detail/resize_policy/sample_resize_policy.hpp \
+	${pb_srcdir}/detail/resize_policy/sample_resize_trigger.hpp \
+	${pb_srcdir}/detail/resize_policy/sample_size_policy.hpp \
+	${pb_srcdir}/detail/splay_tree_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/splay_tree_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/splay_tree_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/splay_tree_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/splay_tree_/info_fn_imps.hpp \
+	${pb_srcdir}/detail/splay_tree_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/splay_tree_/node.hpp \
+	${pb_srcdir}/detail/splay_tree_/splay_fn_imps.hpp \
+	${pb_srcdir}/detail/splay_tree_/splay_tree_.hpp \
+	${pb_srcdir}/detail/splay_tree_/split_join_fn_imps.hpp \
+	${pb_srcdir}/detail/splay_tree_/traits.hpp \
+	${pb_srcdir}/detail/standard_policies.hpp \
+	${pb_srcdir}/detail/thin_heap_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/thin_heap_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/thin_heap_/erase_fn_imps.hpp
+
+pb_headers7 = \
+	${pb_srcdir}/detail/thin_heap_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/thin_heap_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/thin_heap_/split_join_fn_imps.hpp \
+	${pb_srcdir}/detail/thin_heap_/thin_heap_.hpp \
+	${pb_srcdir}/detail/thin_heap_/trace_fn_imps.hpp \
+	${pb_srcdir}/detail/tree_policy/node_metadata_selector.hpp \
+	${pb_srcdir}/detail/tree_policy/order_statistics_imp.hpp \
+	${pb_srcdir}/detail/tree_policy/sample_tree_node_update.hpp \
+	${pb_srcdir}/detail/tree_trace_base.hpp \
+	${pb_srcdir}/detail/trie_policy/node_metadata_selector.hpp \
+	${pb_srcdir}/detail/trie_policy/order_statistics_imp.hpp \
+	${pb_srcdir}/detail/trie_policy/prefix_search_node_update_imp.hpp \
+	${pb_srcdir}/detail/trie_policy/sample_trie_access_traits.hpp \
+	${pb_srcdir}/detail/trie_policy/sample_trie_node_update.hpp \
+	${pb_srcdir}/detail/trie_policy/trie_string_access_traits_imp.hpp \
+	${pb_srcdir}/detail/trie_policy/trie_policy_base.hpp \
+	${pb_srcdir}/detail/types_traits.hpp \
+	${pb_srcdir}/detail/type_utils.hpp \
+	${pb_srcdir}/detail/unordered_iterator/const_iterator.hpp \
+	${pb_srcdir}/detail/unordered_iterator/point_const_iterator.hpp \
+	${pb_srcdir}/detail/unordered_iterator/iterator.hpp \
+	${pb_srcdir}/detail/unordered_iterator/point_iterator.hpp
+
+
+ext_srcdir = ${glibcxx_srcdir}/include/ext
+ext_builddir = ./ext
+ext_headers = \
+	${ext_srcdir}/algorithm \
+	${ext_srcdir}/aligned_buffer.h \
+	${ext_srcdir}/alloc_traits.h \
+	${ext_srcdir}/atomicity.h \
+	${ext_srcdir}/bitmap_allocator.h \
+	${ext_srcdir}/cast.h \
+	${ext_srcdir}/cmath \
+	${ext_srcdir}/codecvt_specializations.h \
+	${ext_srcdir}/concurrence.h \
+	${ext_srcdir}/debug_allocator.h \
+	${ext_srcdir}/enc_filebuf.h \
+	${ext_srcdir}/extptr_allocator.h \
+	${ext_srcdir}/stdio_filebuf.h \
+	${ext_srcdir}/stdio_sync_filebuf.h \
+	${ext_srcdir}/functional \
+	${ext_srcdir}/iterator \
+	${ext_srcdir}/malloc_allocator.h \
+	${ext_srcdir}/memory \
+	${ext_srcdir}/mt_allocator.h \
+	${ext_srcdir}/new_allocator.h \
+	${ext_srcdir}/numeric \
+	${ext_srcdir}/numeric_traits.h \
+	${ext_srcdir}/pod_char_traits.h \
+	${ext_srcdir}/pointer.h \
+	${ext_srcdir}/pool_allocator.h \
+	${ext_srcdir}/rb_tree \
+	${ext_srcdir}/random \
+	${ext_srcdir}/random.tcc \
+	${ext_srcdir}/rope \
+	${ext_srcdir}/ropeimpl.h \
+	${ext_srcdir}/slist \
+	${ext_srcdir}/string_conversions.h \
+	${ext_srcdir}/throw_allocator.h \
+	${ext_srcdir}/typelist.h \
+	${ext_srcdir}/type_traits.h \
+	${ext_srcdir}/rc_string_base.h \
+	${ext_srcdir}/sso_string_base.h \
+	${ext_srcdir}/vstring.h \
+	${ext_srcdir}/vstring.tcc \
+	${ext_srcdir}/vstring_fwd.h \
+	${ext_srcdir}/vstring_util.h \
+	${ext_compat_headers}
+
+ext_compat_headers = \
+	${backward_srcdir}/hash_set \
+	${backward_srcdir}/hash_map
+
+ext_host_headers = \
+	${glibcxx_srcdir}/${CPU_OPT_EXT_RANDOM}
+
+tr1_srcdir = ${glibcxx_srcdir}/include/tr1
+tr1_builddir = ./tr1
+tr1_headers = \
+	${tr1_srcdir}/array \
+	${tr1_srcdir}/bessel_function.tcc \
+	${tr1_srcdir}/beta_function.tcc \
+	${tr1_srcdir}/ccomplex \
+	${tr1_srcdir}/cctype \
+	${tr1_srcdir}/cfenv \
+	${tr1_srcdir}/cfloat \
+	${tr1_srcdir}/cinttypes \
+	${tr1_srcdir}/climits \
+	${tr1_srcdir}/cmath \
+	${tr1_srcdir}/complex \
+	${tr1_srcdir}/complex.h \
+	${tr1_srcdir}/cstdarg \
+	${tr1_srcdir}/cstdbool \
+	${tr1_srcdir}/cstdint \
+	${tr1_srcdir}/cstdio \
+	${tr1_srcdir}/cstdlib \
+	${tr1_srcdir}/ctgmath \
+	${tr1_srcdir}/ctime \
+	${tr1_srcdir}/ctype.h \
+	${tr1_srcdir}/cwchar \
+	${tr1_srcdir}/cwctype \
+	${tr1_srcdir}/ell_integral.tcc \
+	${tr1_srcdir}/exp_integral.tcc \
+	${tr1_srcdir}/fenv.h \
+	${tr1_srcdir}/float.h \
+	${tr1_srcdir}/functional \
+	${tr1_srcdir}/functional_hash.h \
+	${tr1_srcdir}/gamma.tcc \
+	${tr1_srcdir}/hypergeometric.tcc \
+	${tr1_srcdir}/hashtable.h \
+	${tr1_srcdir}/hashtable_policy.h \
+	${tr1_srcdir}/inttypes.h \
+	${tr1_srcdir}/limits.h \
+	${tr1_srcdir}/math.h \
+	${tr1_srcdir}/memory \
+	${tr1_srcdir}/modified_bessel_func.tcc \
+	${tr1_srcdir}/poly_hermite.tcc \
+	${tr1_srcdir}/poly_laguerre.tcc \
+	${tr1_srcdir}/legendre_function.tcc \
+	${tr1_srcdir}/random \
+	${tr1_srcdir}/random.h \
+	${tr1_srcdir}/random.tcc \
+	${tr1_srcdir}/regex \
+	${tr1_srcdir}/riemann_zeta.tcc \
+	${tr1_srcdir}/shared_ptr.h \
+	${tr1_srcdir}/special_function_util.h \
+	${tr1_srcdir}/stdarg.h \
+	${tr1_srcdir}/stdbool.h \
+	${tr1_srcdir}/stdint.h \
+	${tr1_srcdir}/stdio.h \
+	${tr1_srcdir}/stdlib.h \
+	${tr1_srcdir}/tgmath.h \
+	${tr1_srcdir}/tuple \
+	${tr1_srcdir}/type_traits \
+	${tr1_srcdir}/unordered_map \
+	${tr1_srcdir}/unordered_map.h \
+	${tr1_srcdir}/unordered_set \
+	${tr1_srcdir}/unordered_set.h \
+	${tr1_srcdir}/utility \
+	${tr1_srcdir}/wchar.h \
+	${tr1_srcdir}/wctype.h
+
+tr2_srcdir = ${glibcxx_srcdir}/include/tr2
+tr2_builddir = ./tr2
+tr2_headers = \
+	${tr2_srcdir}/bool_set \
+	${tr2_srcdir}/bool_set.tcc \
+	${tr2_srcdir}/dynamic_bitset \
+	${tr2_srcdir}/dynamic_bitset.tcc \
+	${tr2_srcdir}/ratio \
+	${tr2_srcdir}/type_traits
+
+decimal_srcdir = ${glibcxx_srcdir}/include/decimal
+decimal_builddir = ./decimal
+decimal_headers = \
+	${decimal_srcdir}/decimal \
+	${decimal_srcdir}/decimal.h
+
+# Post-C++11 TS's
+experimental_srcdir = ${glibcxx_srcdir}/include/experimental
+experimental_builddir = ./experimental
+experimental_headers = \
+	${experimental_srcdir}/algorithm \
+	${experimental_srcdir}/any \
+	${experimental_srcdir}/array \
+	${experimental_srcdir}/buffer \
+	${experimental_srcdir}/chrono \
+	${experimental_srcdir}/deque \
+	${experimental_srcdir}/executor \
+	${experimental_srcdir}/forward_list \
+	${experimental_srcdir}/functional \
+	${experimental_srcdir}/internet \
+	${experimental_srcdir}/io_context \
+	${experimental_srcdir}/iterator \
+	${experimental_srcdir}/list \
+	${experimental_srcdir}/map \
+	${experimental_srcdir}/memory \
+	${experimental_srcdir}/memory_resource \
+	${experimental_srcdir}/net \
+	${experimental_srcdir}/netfwd \
+	${experimental_srcdir}/numeric \
+	${experimental_srcdir}/optional \
+	${experimental_srcdir}/propagate_const \
+	${experimental_srcdir}/random \
+	${experimental_srcdir}/ratio \
+	${experimental_srcdir}/regex \
+	${experimental_srcdir}/set \
+	${experimental_srcdir}/socket \
+	${experimental_srcdir}/source_location \
+	${experimental_srcdir}/string \
+	${experimental_srcdir}/string_view \
+	${experimental_srcdir}/system_error \
+	${experimental_srcdir}/timer \
+	${experimental_srcdir}/tuple \
+	${experimental_srcdir}/type_traits \
+	${experimental_srcdir}/unordered_map \
+	${experimental_srcdir}/unordered_set \
+	${experimental_srcdir}/utility \
+	${experimental_srcdir}/vector \
+	${experimental_filesystem_headers}
+
+experimental_bits_srcdir = ${glibcxx_srcdir}/include/experimental/bits
+experimental_bits_builddir = ./experimental/bits
+experimental_bits_headers = \
+	${experimental_bits_srcdir}/lfts_config.h \
+	${experimental_bits_srcdir}/net.h \
+	${experimental_bits_srcdir}/shared_ptr.h \
+	${experimental_bits_srcdir}/string_view.tcc \
+	${experimental_bits_filesystem_headers}
+
+if ENABLE_FILESYSTEM_TS
+experimental_filesystem_headers = \
+	${experimental_srcdir}/filesystem
+experimental_bits_filesystem_headers = \
+	${experimental_bits_srcdir}/fs_dir.h \
+	${experimental_bits_srcdir}/fs_fwd.h \
+	${experimental_bits_srcdir}/fs_ops.h \
+	${experimental_bits_srcdir}/fs_path.h
+else
+experimental_filesystem_headers =
+experimental_bits_filesystem_headers =
+endif
+
+# This is the common subset of C++ files that all three "C" header models use.
+c_base_srcdir = $(C_INCLUDE_DIR)
+c_base_builddir = .
+c_base_headers = \
+	${c_base_srcdir}/cassert \
+	${c_base_srcdir}/ccomplex \
+	${c_base_srcdir}/cctype \
+	${c_base_srcdir}/cerrno \
+	${c_base_srcdir}/cfenv \
+	${c_base_srcdir}/cfloat \
+	${c_base_srcdir}/cinttypes \
+	${c_base_srcdir}/ciso646 \
+	${c_base_srcdir}/climits \
+	${c_base_srcdir}/clocale \
+	${c_base_srcdir}/cmath \
+	${c_base_srcdir}/csetjmp \
+	${c_base_srcdir}/csignal \
+	${c_base_srcdir}/cstdalign \
+	${c_base_srcdir}/cstdarg \
+	${c_base_srcdir}/cstdbool \
+	${c_base_srcdir}/cstddef \
+	${c_base_srcdir}/cstdint \
+	${c_base_srcdir}/cstdio \
+	${c_base_srcdir}/cstdlib \
+	${c_base_srcdir}/cstring \
+	${c_base_srcdir}/ctgmath \
+	${c_base_srcdir}/ctime \
+	${c_base_srcdir}/cuchar \
+	${c_base_srcdir}/cwchar \
+	${c_base_srcdir}/cwctype
+
+# "C" compatibility headers.
+c_compatibility_srcdir = ${glibcxx_srcdir}/include/c_compatibility
+c_compatibility_builddir = .
+
+if GLIBCXX_C_HEADERS_C_STD
+c_compatibility_headers =
+endif
+
+if GLIBCXX_C_HEADERS_C_GLOBAL
+c_compatibility_headers = \
+	${c_compatibility_srcdir}/complex.h \
+	${c_compatibility_srcdir}/fenv.h \
+	${c_compatibility_srcdir}/tgmath.h \
+	${c_compatibility_srcdir}/math.h \
+	${c_compatibility_srcdir}/stdlib.h
+endif
+
+if GLIBCXX_C_HEADERS_C
+c_compatibility_headers = \
+	${c_compatibility_srcdir}/assert.h \
+	${c_compatibility_srcdir}/complex.h \
+	${c_compatibility_srcdir}/ctype.h \
+	${c_compatibility_srcdir}/errno.h \
+	${c_compatibility_srcdir}/fenv.h \
+	${c_compatibility_srcdir}/float.h \
+	${c_compatibility_srcdir}/inttypes.h \
+	${c_compatibility_srcdir}/iso646.h \
+	${c_compatibility_srcdir}/limits.h \
+	${c_compatibility_srcdir}/locale.h \
+	${c_compatibility_srcdir}/math.h \
+	${c_compatibility_srcdir}/setjmp.h \
+	${c_compatibility_srcdir}/signal.h \
+	${c_compatibility_srcdir}/stdarg.h \
+	${c_compatibility_srcdir}/stdbool.h \
+	${c_compatibility_srcdir}/stddef.h \
+	${c_compatibility_srcdir}/stdint.h \
+	${c_compatibility_srcdir}/stdio.h \
+	${c_compatibility_srcdir}/stdlib.h \
+	${c_compatibility_srcdir}/string.h \
+	${c_compatibility_srcdir}/tgmath.h \
+	${c_compatibility_srcdir}/time.h \
+	${c_compatibility_srcdir}/uchar.h \
+	${c_compatibility_srcdir}/wchar.h \
+	${c_compatibility_srcdir}/wctype.h
+endif
+
+# Debug mode headers
+debug_srcdir = ${glibcxx_srcdir}/include/debug
+debug_builddir = ./debug
+debug_headers = \
+	${debug_srcdir}/array \
+	${debug_srcdir}/assertions.h \
+	${debug_srcdir}/bitset \
+	${debug_srcdir}/debug.h \
+	${debug_srcdir}/deque \
+	${debug_srcdir}/formatter.h \
+	${debug_srcdir}/forward_list \
+	${debug_srcdir}/functions.h \
+	${debug_srcdir}/helper_functions.h \
+	${debug_srcdir}/list \
+	${debug_srcdir}/map \
+	${debug_srcdir}/macros.h \
+	${debug_srcdir}/map.h \
+	${debug_srcdir}/multimap.h \
+	${debug_srcdir}/multiset.h \
+	${debug_srcdir}/safe_base.h \
+	${debug_srcdir}/safe_container.h \
+	${debug_srcdir}/safe_iterator.h \
+	${debug_srcdir}/safe_iterator.tcc \
+	${debug_srcdir}/safe_local_iterator.h \
+	${debug_srcdir}/safe_local_iterator.tcc \
+	${debug_srcdir}/safe_sequence.h \
+	${debug_srcdir}/safe_sequence.tcc \
+	${debug_srcdir}/safe_unordered_base.h \
+	${debug_srcdir}/safe_unordered_container.h \
+	${debug_srcdir}/safe_unordered_container.tcc \
+	${debug_srcdir}/set \
+	${debug_srcdir}/set.h \
+	${debug_srcdir}/stl_iterator.h \
+	${debug_srcdir}/string \
+	${debug_srcdir}/unordered_map \
+	${debug_srcdir}/unordered_set \
+	${debug_srcdir}/vector
+
+# Parallel mode headers
+parallel_srcdir = ${glibcxx_srcdir}/include/parallel
+parallel_builddir = ./parallel
+parallel_headers = \
+	${parallel_srcdir}/algo.h \
+	${parallel_srcdir}/algobase.h \
+	${parallel_srcdir}/algorithm \
+	${parallel_srcdir}/algorithmfwd.h \
+	${parallel_srcdir}/balanced_quicksort.h \
+	${parallel_srcdir}/base.h \
+	${parallel_srcdir}/basic_iterator.h \
+	${parallel_srcdir}/checkers.h \
+	${parallel_srcdir}/compatibility.h \
+	${parallel_srcdir}/compiletime_settings.h \
+	${parallel_srcdir}/equally_split.h \
+	${parallel_srcdir}/features.h \
+	${parallel_srcdir}/find.h \
+	${parallel_srcdir}/find_selectors.h \
+	${parallel_srcdir}/for_each.h \
+	${parallel_srcdir}/for_each_selectors.h \
+	${parallel_srcdir}/iterator.h \
+	${parallel_srcdir}/list_partition.h \
+	${parallel_srcdir}/losertree.h \
+	${parallel_srcdir}/merge.h \
+	${parallel_srcdir}/multiseq_selection.h \
+	${parallel_srcdir}/multiway_merge.h \
+	${parallel_srcdir}/multiway_mergesort.h \
+	${parallel_srcdir}/numeric \
+	${parallel_srcdir}/numericfwd.h \
+	${parallel_srcdir}/omp_loop.h \
+	${parallel_srcdir}/omp_loop_static.h \
+	${parallel_srcdir}/par_loop.h \
+	${parallel_srcdir}/parallel.h \
+	${parallel_srcdir}/partial_sum.h \
+	${parallel_srcdir}/partition.h \
+	${parallel_srcdir}/queue.h \
+	${parallel_srcdir}/quicksort.h \
+	${parallel_srcdir}/random_number.h \
+	${parallel_srcdir}/random_shuffle.h \
+	${parallel_srcdir}/search.h \
+	${parallel_srcdir}/set_operations.h \
+	${parallel_srcdir}/settings.h \
+	${parallel_srcdir}/sort.h \
+	${parallel_srcdir}/tags.h \
+	${parallel_srcdir}/types.h \
+	${parallel_srcdir}/unique_copy.h \
+	${parallel_srcdir}/workstealing.h
+
+# Some "C" header schemes require the "C" compatibility headers.
+# For --enable-cheaders=c_std
+if GLIBCXX_C_HEADERS_COMPATIBILITY
+c_compatibility_headers_extra = ${c_compatibility_headers}
+else
+c_compatibility_headers_extra =
+endif
+
+host_srcdir = ${glibcxx_srcdir}/$(OS_INC_SRCDIR)
+host_builddir = ./${host_alias}/bits
+host_installdir = ${gxx_include_dir}/${host_alias}$(MULTISUBDIR)/bits
+host_headers = \
+	${host_srcdir}/ctype_base.h \
+	${host_srcdir}/ctype_inline.h \
+	${host_srcdir}/os_defines.h \
+	${glibcxx_srcdir}/$(ATOMIC_WORD_SRCDIR)/atomic_word.h \
+	${glibcxx_srcdir}/$(ABI_TWEAKS_SRCDIR)/cxxabi_tweaks.h \
+	${glibcxx_srcdir}/$(CPU_DEFINES_SRCDIR)/cpu_defines.h \
+	${glibcxx_srcdir}/$(ERROR_CONSTANTS_SRCDIR)/error_constants.h \
+	${glibcxx_srcdir}/include/precompiled/stdc++.h \
+	${glibcxx_srcdir}/include/precompiled/stdtr1c++.h \
+	${glibcxx_srcdir}/include/precompiled/extc++.h
+
+# Non-installed host_header files.
+COMPATIBILITY_H = config/abi/compatibility.h
+host_headers_noinst = \
+	${glibcxx_srcdir}/$(CLOCALE_INTERNAL_H) \
+	${glibcxx_srcdir}/$(COMPATIBILITY_H)
+
+# These host_headers_extra files are all built with ad hoc naming rules.
+host_headers_extra = \
+	${host_builddir}/basic_file.h \
+	${host_builddir}/c++config.h \
+	${host_builddir}/c++allocator.h \
+	${host_builddir}/c++io.h \
+	${host_builddir}/c++locale.h \
+	${host_builddir}/messages_members.h \
+	${host_builddir}/time_members.h
+
+thread_host_headers = \
+	${host_builddir}/gthr.h \
+	${host_builddir}/gthr-single.h \
+	${host_builddir}/gthr-posix.h \
+	${host_builddir}/gthr-default.h
+
+
+pch1_source = ${glibcxx_srcdir}/include/precompiled/stdc++.h
+pch1_output_builddir = ${host_builddir}/stdc++.h.gch
+pch1_output_anchor = ${host_builddir}/stdc++.h
+pch1_output_installdir = ${host_installdir}/stdc++.h.gch
+pch1a_output = ${pch1_output_builddir}/O2ggnu++0x.gch
+pch1b_output = ${pch1_output_builddir}/O2g.gch
+pch1_output = ${pch1a_output} ${pch1b_output}
+
+pch2_source = ${glibcxx_srcdir}/include/precompiled/stdtr1c++.h
+pch2_output_builddir = ${host_builddir}/stdtr1c++.h.gch
+pch2_output_anchor = ${host_builddir}/stdtr1c++.h
+pch2_output_installdir = ${host_installdir}/stdtr1c++.h.gch
+pch2_output = ${pch2_output_builddir}/O2g.gch
+
+pch3_source = ${glibcxx_srcdir}/include/precompiled/extc++.h
+pch3_output_builddir = ${host_builddir}/extc++.h.gch
+pch3_output_anchor = ${host_builddir}/extc++.h
+pch3_output_installdir = ${host_installdir}/extc++.h.gch
+pch3_output = ${pch3_output_builddir}/O2g.gch
+
+
+pch_output = ${pch1_output} ${pch2_output} ${pch3_output}
+pch_output_dirs = \
+	${pch1_output_builddir} ${pch2_output_builddir} ${pch3_output_builddir}
+pch_output_anchors = \
+	${pch1_output_anchor} ${pch2_output_anchor} ${pch3_output_anchor}
+PCHFLAGS=-x c++-header -nostdinc++ $(CXXFLAGS) $(VTV_PCH_CXXFLAGS)
+if GLIBCXX_BUILD_PCH
+pch_build = ${pch_output}
+else
+pch_build =
+endif
+
+# List of all timestamp files.  By keeping only one copy of this list, both
+# CLEANFILES and all-local are kept up-to-date.
+allstamped = \
+	stamp-std stamp-bits stamp-bits-sup stamp-pstl stamp-c_base stamp-c_compatibility \
+	stamp-backward stamp-ext stamp-pb stamp-tr1 stamp-tr2 stamp-decimal \
+	stamp-experimental stamp-experimental-bits stamp-debug stamp-parallel \
+	stamp-host
+
+# List of all files that are created by explicit building, editing, or
+# catenation.
+allcreated = \
+	${host_builddir}/c++config.h \
+	${host_builddir}/largefile-config.h \
+	${thread_host_headers} \
+	${pch_build}
+
+# Here are the rules for building the headers
+all-local: ${allstamped} ${allcreated}
+
+# Ignore errors from 'mkdir -p' to avoid parallel make failure on
+# systems with broken mkdir.  Call mkdir unconditionally because
+# it is just as cheap to avoid going through the shell.
+# Ignore errors from $(LN_S) because the links may already exist.
+stamp-std: ${std_headers}
+	@-mkdir -p ${std_builddir}
+	@-cd ${std_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-std
+
+stamp-bits: ${bits_headers}
+	@-mkdir -p ${bits_builddir}
+	@-cd ${bits_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-bits
+
+stamp-bits-sup: stamp-bits ${bits_sup_headers}
+	@-cd ${bits_builddir} && $(LN_S) ${bits_sup_headers} . 2>/dev/null
+	@$(STAMP) stamp-bits-sup
+
+stamp-pstl: ${pstl_headers}
+	@-mkdir -p ${pstl_builddir}
+	@-cd ${pstl_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-pstl
+
+stamp-c_base: ${c_base_headers}
+	@-mkdir -p ${c_base_builddir}
+	@-cd ${c_base_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-c_base
+
+stamp-c_base_extra: ${c_base_headers_extra}
+	@-mkdir -p ${bits_builddir}
+	@-cd ${bits_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-c_base_extra
+
+stamp-c_compatibility: ${c_compatibility_headers_extra}
+	@-mkdir -p ${c_compatibility_builddir}
+	@-if [ ! -z "${c_compatibility_headers_extra}" ]; then \
+	  cd ${c_compatibility_builddir} && $(LN_S) $? . 2>/dev/null ;\
+	fi
+	@$(STAMP) stamp-c_compatibility
+
+stamp-backward: ${backward_headers}
+	@-mkdir -p ${backward_builddir}
+	@-cd ${backward_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-backward
+
+stamp-ext: ${ext_headers}
+	@-mkdir -p ${ext_builddir}
+	@-cd ${ext_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-ext
+
+# Have to deal with nested include directories, gah! Strip off source
+# directory before making the link.
+# XXX check  ${pb_headers}
+stamp-pb:
+	@if [ ! -d "${pb_builddir}" ]; then \
+	    mkdir -p ${pb_subdirs} ;\
+	fi
+	@if [ ! -f stamp-pb ]; then \
+	    cd ${pb_builddir} && for h in ${pb_headers1}; do \
+		build_name=`echo $$h | sed -e "s|${pb_srcdir}|.|g"` ;\
+		$(LN_S) $$h $${build_name} || true ;\
+	      done ;\
+	fi
+	@if [ ! -f stamp-pb ]; then \
+	    cd ${pb_builddir} && for h in ${pb_headers2}; do \
+		build_name=`echo $$h | sed -e "s|${pb_srcdir}|.|g"` ;\
+		$(LN_S) $$h $${build_name} || true ;\
+	      done ;\
+	fi
+	@if [ ! -f stamp-pb ]; then \
+	    cd ${pb_builddir} && for h in ${pb_headers3}; do \
+		build_name=`echo $$h | sed -e "s|${pb_srcdir}|.|g"` ;\
+		$(LN_S) $$h $${build_name} || true ;\
+	      done ;\
+	fi
+	@if [ ! -f stamp-pb ]; then \
+	    cd ${pb_builddir} && for h in ${pb_headers4}; do \
+		build_name=`echo $$h | sed -e "s|${pb_srcdir}|.|g"` ;\
+		$(LN_S) $$h $${build_name} || true ;\
+	      done ;\
+	fi
+	@if [ ! -f stamp-pb ]; then \
+	    cd ${pb_builddir} && for h in ${pb_headers5}; do \
+		build_name=`echo $$h | sed -e "s|${pb_srcdir}|.|g"` ;\
+		$(LN_S) $$h $${build_name} || true ;\
+	      done ;\
+	fi
+	@if [ ! -f stamp-pb ]; then \
+	    cd ${pb_builddir} && for h in ${pb_headers6}; do \
+		build_name=`echo $$h | sed -e "s|${pb_srcdir}|.|g"` ;\
+		$(LN_S) $$h $${build_name} || true ;\
+	      done ;\
+	fi
+	@if [ ! -f stamp-pb ]; then \
+	    cd ${pb_builddir} && for h in ${pb_headers7}; do \
+		build_name=`echo $$h | sed -e "s|${pb_srcdir}|.|g"` ;\
+		$(LN_S) $$h $${build_name} || true ;\
+	      done ;\
+	fi
+	$(STAMP) stamp-pb
+
+stamp-tr1: ${tr1_headers}
+	@-mkdir -p ${tr1_builddir}
+	@-cd ${tr1_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-tr1
+
+stamp-tr2: ${tr2_headers}
+	@-mkdir -p ${tr2_builddir}
+	@-cd ${tr2_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-tr2
+
+stamp-decimal: ${decimal_headers}
+	@-mkdir -p ${decimal_builddir}
+	@-cd ${decimal_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-decimal
+
+stamp-experimental: ${experimental_headers}
+	@-mkdir -p ${experimental_builddir}
+	@-cd ${experimental_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-experimental
+
+stamp-experimental-bits: ${experimental_bits_headers}
+	@-mkdir -p ${experimental_bits_builddir}
+	@-cd ${experimental_bits_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-experimental-bits
+
+stamp-debug: ${debug_headers}
+	@-mkdir -p ${debug_builddir}
+	@-cd ${debug_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-debug
+
+stamp-parallel: ${parallel_headers}
+	@-mkdir -p ${parallel_builddir}
+	@-cd ${parallel_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-parallel
+
+stamp-${host_alias}:
+	@-mkdir -p ${host_builddir}
+	@-mkdir -p ${host_builddir}/../ext
+	@$(STAMP) stamp-${host_alias}
+
+# Host includes static.
+# XXX Missing dependency info for {host_headers_extra}
+stamp-host: ${host_headers} ${bits_host_headers} ${ext_host_headers} ${host_headers_noinst} stamp-${host_alias}
+	@cd ${host_builddir} && {\
+	  $(LN_S) ${host_headers} ${bits_host_headers} . || true ;\
+	  $(LN_S) ${glibcxx_srcdir}/$(BASIC_FILE_H) basic_file.h || true ;\
+	  $(LN_S) ${glibcxx_srcdir}/$(ALLOCATOR_H) c++allocator.h || true ;\
+	  $(LN_S) ${glibcxx_srcdir}/$(CSTDIO_H) c++io.h || true ;\
+	  $(LN_S) ${glibcxx_srcdir}/$(CLOCALE_H) c++locale.h || true ;\
+	  $(LN_S) ${glibcxx_srcdir}/$(CLOCALE_INTERNAL_H) . || true ;\
+	  $(LN_S) ${glibcxx_srcdir}/$(COMPATIBILITY_H) . || true ;\
+	  $(LN_S) ${glibcxx_srcdir}/$(CMESSAGES_H) messages_members.h || true ;\
+	  $(LN_S) ${glibcxx_srcdir}/$(CTIME_H) time_members.h || true;\
+	} 2>/dev/null
+	@cd ${host_builddir}/../ext && {\
+	  $(LN_S) ${ext_host_headers} . || true ;\
+	} 2>/dev/null
+	$(STAMP) stamp-host
+
+# Host includes dynamic.
+if ENABLE_SYMVERS_GNU_NAMESPACE
+stamp-namespace-version:
+	echo 1 > stamp-namespace-version
+else
+stamp-namespace-version:
+	echo 0 > stamp-namespace-version
+endif
+
+if ENABLE_EXTERN_TEMPLATE
+stamp-extern-template:
+	echo 1 > stamp-extern-template
+else
+stamp-extern-template:
+	echo 0 > stamp-extern-template
+endif
+
+if ENABLE_VISIBILITY
+stamp-visibility:
+	echo 1 > stamp-visibility
+else
+stamp-visibility:
+	echo 0 > stamp-visibility
+endif
+
+if ENABLE_DUAL_ABI
+stamp-dual-abi:
+	echo 1 > stamp-dual-abi
+else
+stamp-dual-abi:
+	echo 0 > stamp-dual-abi
+endif
+
+if ENABLE_CXX11_ABI
+stamp-cxx11-abi:
+	echo 1 > stamp-cxx11-abi
+else
+stamp-cxx11-abi:
+	echo 0 > stamp-cxx11-abi
+endif
+
+if ENABLE_ALLOCATOR_NEW
+stamp-allocator-new:
+	echo 1 > stamp-allocator-new
+else
+stamp-allocator-new:
+	echo 0 > stamp-allocator-new
+endif
+
+if ENABLE_FLOAT128
+stamp-float128:
+	echo 'define _GLIBCXX_USE_FLOAT128 1' > stamp-float128
+else
+stamp-float128:
+	echo 'undef _GLIBCXX_USE_FLOAT128' > stamp-float128
+endif
+
+# This header is not installed, it's only used to build libstdc++ itself.
+${host_builddir}/largefile-config.h: ${CONFIG_HEADER}
+	@rm -f $@.tmp
+	@-grep 'define _DARWIN_USE_64_BIT_INODE' ${CONFIG_HEADER} >> $@.tmp
+	@-grep 'define _FILE_OFFSET_BITS' ${CONFIG_HEADER} >> $@.tmp
+	@-grep 'define _LARGE_FILES' ${CONFIG_HEADER} >> $@.tmp
+	@mv $@.tmp $@
+
+# NB: The non-empty default ldbl_compat works around an AIX sed
+# oddity, see libstdc++/31957 for details.
+${host_builddir}/c++config.h: ${CONFIG_HEADER} \
+			      ${glibcxx_srcdir}/include/bits/c++config \
+			      ${host_builddir}/largefile-config.h \
+			      stamp-${host_alias} \
+			      ${toplevel_srcdir}/gcc/DATESTAMP \
+			      stamp-namespace-version \
+			      stamp-visibility \
+			      stamp-extern-template \
+			      stamp-dual-abi \
+			      stamp-cxx11-abi \
+			      stamp-allocator-new \
+			      stamp-float128
+	@date=`cat ${toplevel_srcdir}/gcc/DATESTAMP` ;\
+	release=`sed 's/^\([0-9]*\).*$$/\1/' ${toplevel_srcdir}/gcc/BASE-VER` ;\
+	ns_version=`cat stamp-namespace-version` ;\
+	visibility=`cat stamp-visibility` ;\
+	externtemplate=`cat stamp-extern-template` ;\
+	dualabi=`cat stamp-dual-abi` ;\
+	cxx11abi=`cat stamp-cxx11-abi` ;\
+	allocatornew=`cat stamp-allocator-new` ;\
+	float128=`cat stamp-float128` ;\
+	ldbl_compat='s,g,g,' ;\
+	grep "^[	 ]*#[	 ]*define[	 ][	 ]*_GLIBCXX_LONG_DOUBLE_COMPAT[	 ][	 ]*1[	 ]*$$" \
+	${CONFIG_HEADER} > /dev/null 2>&1 \
+	&& ldbl_compat='s,^#undef _GLIBCXX_LONG_DOUBLE_COMPAT$$,#define _GLIBCXX_LONG_DOUBLE_COMPAT 1,' ;\
+	sed -e "s,define __GLIBCXX__,define __GLIBCXX__ $$date," \
+	-e "s,define _GLIBCXX_RELEASE,define _GLIBCXX_RELEASE $$release," \
+	-e "s,define _GLIBCXX_INLINE_VERSION, define _GLIBCXX_INLINE_VERSION $$ns_version," \
+	-e "s,define _GLIBCXX_HAVE_ATTRIBUTE_VISIBILITY, define _GLIBCXX_HAVE_ATTRIBUTE_VISIBILITY $$visibility," \
+	-e "s,define _GLIBCXX_EXTERN_TEMPLATE$$, define _GLIBCXX_EXTERN_TEMPLATE $$externtemplate," \
+	-e "s,define _GLIBCXX_USE_DUAL_ABI, define _GLIBCXX_USE_DUAL_ABI $$dualabi," \
+	-e "s,define _GLIBCXX_USE_CXX11_ABI, define _GLIBCXX_USE_CXX11_ABI $$cxx11abi," \
+	-e "s,define _GLIBCXX_USE_ALLOCATOR_NEW, define _GLIBCXX_USE_ALLOCATOR_NEW $$allocatornew," \
+	-e "s,define _GLIBCXX_USE_FLOAT128,$$float128," \
+	-e "$$ldbl_compat" \
+	    < ${glibcxx_srcdir}/include/bits/c++config > $@ ;\
+	sed -e 's/HAVE_/_GLIBCXX_HAVE_/g' \
+	    -e 's/PACKAGE/_GLIBCXX_PACKAGE/g' \
+	    -e 's/VERSION/_GLIBCXX_VERSION/g' \
+	    -e 's/WORDS_/_GLIBCXX_WORDS_/g' \
+	    -e 's/_DARWIN_USE_64_BIT_INODE/_GLIBCXX_DARWIN_USE_64_BIT_INODE/g' \
+	    -e 's/_FILE_OFFSET_BITS/_GLIBCXX_FILE_OFFSET_BITS/g' \
+	    -e 's/_LARGE_FILES/_GLIBCXX_LARGE_FILES/g' \
+	    -e 's/ICONV_CONST/_GLIBCXX_ICONV_CONST/g' \
+	    -e '/[	 ]_GLIBCXX_LONG_DOUBLE_COMPAT[	 ]/d' \
+	    < ${CONFIG_HEADER} >> $@ ;\
+	echo "" >> $@ ;\
+	echo "#endif // _GLIBCXX_CXX_CONFIG_H" >> $@
+
+# Host includes for threads
+uppercase = [ABCDEFGHIJKLMNOPQRSTUVWXYZ_]
+
+${host_builddir}/gthr.h: ${toplevel_srcdir}/libgcc/gthr.h stamp-${host_alias}
+	sed -e '/^#pragma/b' \
+	    -e '/^#/s/\(${uppercase}${uppercase}*\)/_GLIBCXX_\1/g' \
+	    -e 's/_GLIBCXX_SUPPORTS_WEAK/__GXX_WEAK__/g' \
+	    -e 's/_GLIBCXX___MINGW32_GLIBCXX___/__MINGW32__/g' \
+	    -e 's,^#include "\(.*\)",#include <bits/\1>,g' \
+	    < $< > $@
+
+${host_builddir}/gthr-single.h: ${toplevel_srcdir}/libgcc/gthr-single.h \
+				  stamp-${host_alias}
+	sed -e 's/\(UNUSED\)/_GLIBCXX_\1/g' \
+	    -e 's/\(GCC${uppercase}*_H\)/_GLIBCXX_\1/g' \
+	    < $< > $@
+
+${host_builddir}/gthr-posix.h: ${toplevel_srcdir}/libgcc/gthr-posix.h \
+				   stamp-${host_alias}
+	sed -e 's/\(UNUSED\)/_GLIBCXX_\1/g' \
+	    -e 's/\(GCC${uppercase}*_H\)/_GLIBCXX_\1/g' \
+	    -e 's/SUPPORTS_WEAK/__GXX_WEAK__/g' \
+	    -e 's/\(${uppercase}*USE_WEAK\)/_GLIBCXX_\1/g' \
+	    < $< > $@
+
+${host_builddir}/gthr-default.h: ${toplevel_srcdir}/libgcc/${thread_header} \
+				   stamp-${host_alias}
+	sed -e 's/\(UNUSED\)/_GLIBCXX_\1/g' \
+	    -e 's/\(GCC${uppercase}*_H\)/_GLIBCXX_\1/g' \
+	    -e 's/SUPPORTS_WEAK/__GXX_WEAK__/g' \
+	    -e 's/\(${uppercase}*USE_WEAK\)/_GLIBCXX_\1/g' \
+	    -e 's,^#include "\(.*\)",#include <bits/\1>,g' \
+	    < $< > $@
+
+# Build two precompiled C++ includes, stdc++.h.gch/*.gch
+${pch1a_output}: ${allstamped} ${host_builddir}/c++config.h ${pch1_source}
+	-mkdir -p ${pch1_output_builddir}
+	$(CXX) $(PCHFLAGS) $(AM_CPPFLAGS) -O2 -g -std=gnu++0x ${pch1_source} \
+	-o $@
+
+${pch1b_output}: ${allstamped} ${host_builddir}/c++config.h ${pch1_source}
+	-mkdir -p ${pch1_output_builddir}
+	$(CXX) $(PCHFLAGS) $(AM_CPPFLAGS) -O2 -g ${pch1_source} -o $@
+
+# Build a precompiled TR1 include, stdtr1c++.h.gch/O2.gch
+${pch2_output}: ${pch2_source} ${pch1_output}
+	-mkdir -p ${pch2_output_builddir}
+	$(CXX) $(PCHFLAGS) $(AM_CPPFLAGS) -O2 -g ${pch2_source} -o $@
+
+# Build a precompiled extension include, extc++.h.gch/O2.gch
+${pch3_output}: ${pch3_source} ${pch2_output}
+	-mkdir -p ${pch3_output_builddir}
+	$(CXX) $(PCHFLAGS) $(AM_CPPFLAGS) -O2 -g ${pch3_source} -o $@
+
+# For robustness sake (in light of junk files or in-source
+# configuration), copy from the build or source tree to the install
+# tree using only the human-maintained file lists and directory
+# components.  Yes, with minor differences, this is sheer duplication
+# of the staging rules above using $(INSTALL_DATA) instead of LN_S and
+# `$(mkinstalldirs)' instead of `mkdir -p'.  In particular,
+# host_headers_extra are taken out of the build tree staging area;
+# the rest are taken from the original source tree.
+
+if GLIBCXX_HOSTED
+install-data-local: install-headers
+else
+install-data-local: install-freestanding-headers
+endif
+
+# This is a subset of the full install-headers rule.  We only need <ciso646>,
+# <cstddef>, <cfloat>, <limits>, <climits>, <version>, <cstdint>, <cstdlib>,
+# <new>, <typeinfo>, <exception>, <initializer_list>, <cstdalign>, <cstdarg>,
+# <concepts>, <cstdbool>, <type_traits>, <bit>, <atomic>,
+# and any files which they include (and which we provide).
+# <new>, <typeinfo>, <exception>, <initializer_list> and <compare>
+# are installed by libsupc++, so only the others and the sub-includes
+# are copied here.
+install-freestanding-headers:
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/bits
+	for file in c++0x_warning.h atomic_base.h concept_check.h move.h; do \
+	  $(INSTALL_DATA) ${glibcxx_srcdir}/include/bits/$${file} $(DESTDIR)${gxx_include_dir}/bits; done
+	$(mkinstalldirs) $(DESTDIR)${host_installdir}
+	for file in ${host_srcdir}/os_defines.h ${host_builddir}/c++config.h \
+	  ${glibcxx_srcdir}/$(ABI_TWEAKS_SRCDIR)/cxxabi_tweaks.h \
+	  ${glibcxx_srcdir}/$(CPU_DEFINES_SRCDIR)/cpu_defines.h; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${host_installdir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${std_builddir}
+	for file in limits type_traits atomic bit concepts version; do \
+	  $(INSTALL_DATA) ${std_builddir}/$${file} $(DESTDIR)${gxx_include_dir}/${std_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${c_base_builddir}
+	for file in ciso646 cstddef cfloat climits cstdint cstdlib \
+	  cstdalign cstdarg cstdbool; do \
+	  $(INSTALL_DATA) ${c_base_builddir}/$${file} $(DESTDIR)${gxx_include_dir}/${c_base_builddir}; done
+
+# The real deal.
+install-headers:
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${bits_builddir}
+	for file in ${bits_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${bits_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${backward_builddir}
+	for file in ${backward_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${backward_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${ext_builddir}
+	for file in ${ext_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${ext_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${pb_builddir}
+	for dir in ${pb_subdirs}; do \
+	  $(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/$${dir} ; done
+	for file in ${pb_headers1}; do \
+	  install_base=$(DESTDIR)${gxx_include_dir}/${pb_builddir} ; \
+	  relative_name=`echo $$file | sed -e "s|${pb_srcdir}|.|g"` ;\
+	  $(INSTALL_DATA) $${file} $${install_base}/$${relative_name} ; done
+	for file in ${pb_headers2}; do \
+	  install_base=$(DESTDIR)${gxx_include_dir}/${pb_builddir} ; \
+	  relative_name=`echo $$file | sed -e "s|${pb_srcdir}|.|g"` ;\
+	  $(INSTALL_DATA) $${file} $${install_base}/$${relative_name} ; done
+	for file in ${pb_headers3}; do \
+	  install_base=$(DESTDIR)${gxx_include_dir}/${pb_builddir} ; \
+	  relative_name=`echo $$file | sed -e "s|${pb_srcdir}|.|g"` ;\
+	  $(INSTALL_DATA) $${file} $${install_base}/$${relative_name} ; done
+	for file in ${pb_headers4}; do \
+	  install_base=$(DESTDIR)${gxx_include_dir}/${pb_builddir} ; \
+	  relative_name=`echo $$file | sed -e "s|${pb_srcdir}|.|g"` ;\
+	  $(INSTALL_DATA) $${file} $${install_base}/$${relative_name} ; done
+	for file in ${pb_headers5}; do \
+	  install_base=$(DESTDIR)${gxx_include_dir}/${pb_builddir} ; \
+	  relative_name=`echo $$file | sed -e "s|${pb_srcdir}|.|g"` ;\
+	  $(INSTALL_DATA) $${file} $${install_base}/$${relative_name} ; done
+	for file in ${pb_headers6}; do \
+	  install_base=$(DESTDIR)${gxx_include_dir}/${pb_builddir} ; \
+	  relative_name=`echo $$file | sed -e "s|${pb_srcdir}|.|g"` ;\
+	  $(INSTALL_DATA) $${file} $${install_base}/$${relative_name} ; done
+	for file in ${pb_headers7}; do \
+	  install_base=$(DESTDIR)${gxx_include_dir}/${pb_builddir} ; \
+	  relative_name=`echo $$file | sed -e "s|${pb_srcdir}|.|g"` ;\
+	  $(INSTALL_DATA) $${file} $${install_base}/$${relative_name} ; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${tr1_builddir}
+	for file in ${tr1_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${tr1_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${tr2_builddir}
+	for file in ${tr2_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${tr2_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${decimal_builddir}
+	for file in ${decimal_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${decimal_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${experimental_builddir}
+	for file in ${experimental_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${experimental_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${experimental_bits_builddir}
+	for file in ${experimental_bits_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${experimental_bits_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${c_base_builddir}
+	for file in ${c_base_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${c_base_builddir}; done
+	c_base_headers_extra_install='$(c_base_headers_extra)';\
+	for file in $$c_base_headers_extra_install; do \
+	  $(INSTALL_DATA) $$file $(DESTDIR)${gxx_include_dir}/${bits_builddir}; done
+	c_compatibility_headers_install='$(c_compatibility_headers_extra)';\
+	for file in $$c_compatibility_headers_install; do \
+	  $(INSTALL_DATA) $$file $(DESTDIR)${gxx_include_dir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${std_builddir}
+	for file in ${std_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${std_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${debug_builddir}
+	for file in ${debug_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${debug_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${parallel_builddir}
+	for file in ${parallel_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${parallel_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${host_installdir}
+	for file in ${host_headers} ${bits_host_headers} ${host_headers_extra} \
+	 ${thread_host_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${host_installdir}; done
+	$(mkinstalldirs) $(DESTDIR)${host_installdir}/../ext
+	for file in ${ext_host_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${host_installdir}/../ext; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${pstl_builddir}
+	for file in ${pstl_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${pstl_builddir}; done
+# By adding these files here, automake will remove them for 'make clean'
+CLEANFILES = ${pch_output} ${pch_output_anchors} stamp-host
+
+# To remove directories.
+clean-local:
+	rm -rf ${pch_output_dirs}
+
+# Stop implicit '.o' make rules from ever stomping on extensionless
+# headers, in the improbable case where some foolish, crack-addled
+# developer tries to create them via make in the include build
+# directory. (This is more of an example of how this kind of rule can
+# be made.)
+.PRECIOUS: $(std_headers) $(c_base_headers) $(tr1_headers) $(tr2_headers)
+	   $(decimal_headers) $(ext_headers) $(experimental_headers)
+	   $(experimental_bits_headers)
+$(std_headers): ; @:
+$(c_base_headers): ; @:
+$(tr1_headers): ; @:
+$(decimal_headers): ; @:
+$(ext_headers): ; @:
+$(experimental_headers): ; @:
+$(experimental_bits_headers): ; @:
+
+if INCLUDE_DIR_NOTPARALLEL
+# See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81797
+.NOTPARALLEL:
+endif
 ## with this library; see the file COPYING3.  If not see
 ## <http://www.gnu.org/licenses/>.
 
diff --git a/libstdc++-v3/Makefile.in b/libstdc++-v3/Makefile.in
index 8f11aaf2810..522f2a56fa5 100644
--- a/libstdc++-v3/Makefile.in
+++ b/libstdc++-v3/Makefile.in
@@ -407,6 +407,1003 @@ WARN_CXXFLAGS = \
 
 # -I/-D flags to pass when compiling.
 AM_CPPFLAGS = $(GLIBCXX_INCLUDES) $(CPPFLAGS)
+
+# Standard C++ includes.
+std_srcdir = ${glibcxx_srcdir}/include/std
+std_builddir = .
+std_headers = \
+	${std_srcdir}/algorithm \
+	${std_srcdir}/any \
+	${std_srcdir}/array \
+	${std_srcdir}/atomic \
+	${std_srcdir}/bit \
+	${std_srcdir}/bitset \
+	${std_srcdir}/charconv \
+	${std_srcdir}/chrono \
+	${std_srcdir}/codecvt \
+	${std_srcdir}/complex \
+	${std_srcdir}/concepts \
+	${std_srcdir}/condition_variable \
+	${std_srcdir}/coroutine \
+	${std_srcdir}/deque \
+	${std_srcdir}/execution \
+	${std_srcdir}/filesystem \
+	${std_srcdir}/forward_list \
+	${std_srcdir}/fstream \
+	${std_srcdir}/functional \
+	${std_srcdir}/future \
+	${std_srcdir}/iomanip \
+	${std_srcdir}/ios \
+	${std_srcdir}/iosfwd \
+	${std_srcdir}/iostream \
+	${std_srcdir}/istream \
+	${std_srcdir}/iterator \
+	${std_srcdir}/limits \
+	${std_srcdir}/list \
+	${std_srcdir}/locale \
+	${std_srcdir}/map \
+	${std_srcdir}/memory \
+	${std_srcdir}/memory_resource \
+	${std_srcdir}/mutex \
+	${std_srcdir}/numbers \
+	${std_srcdir}/numeric \
+	${std_srcdir}/optional \
+	${std_srcdir}/ostream \
+	${std_srcdir}/queue \
+	${std_srcdir}/random \
+	${std_srcdir}/ranges \
+	${std_srcdir}/ratio \
+	${std_srcdir}/regex \
+	${std_srcdir}/scoped_allocator \
+  ${std_srcdir}/semaphore \
+	${std_srcdir}/set \
+	${std_srcdir}/shared_mutex \
+	${std_srcdir}/span \
+	${std_srcdir}/sstream \
+	${std_srcdir}/stack \
+	${std_srcdir}/stdexcept \
+	${std_srcdir}/stop_token \
+	${std_srcdir}/streambuf \
+	${std_srcdir}/string \
+	${std_srcdir}/string_view \
+	${std_srcdir}/system_error \
+	${std_srcdir}/thread \
+	${std_srcdir}/tuple \
+	${std_srcdir}/typeindex \
+	${std_srcdir}/type_traits \
+	${std_srcdir}/unordered_map \
+	${std_srcdir}/unordered_set \
+	${std_srcdir}/utility \
+	${std_srcdir}/valarray \
+	${std_srcdir}/variant \
+	${std_srcdir}/vector \
+	${std_srcdir}/version
+
+bits_srcdir = ${glibcxx_srcdir}/include/bits
+bits_builddir = ./bits
+bits_headers = \
+	${bits_srcdir}/algorithmfwd.h \
+	${bits_srcdir}/alloc_traits.h \
+	${bits_srcdir}/allocated_ptr.h \
+	${bits_srcdir}/allocator.h \
+	${bits_srcdir}/atomic_base.h \
+	${bits_srcdir}/atomic_futex.h \
+	${bits_srcdir}/basic_ios.h \
+	${bits_srcdir}/basic_ios.tcc \
+	${bits_srcdir}/basic_string.h \
+	${bits_srcdir}/basic_string.tcc \
+	${bits_srcdir}/boost_concept_check.h \
+	${bits_srcdir}/c++0x_warning.h \
+	${bits_srcdir}/char_traits.h \
+	${bits_srcdir}/charconv.h \
+	${bits_srcdir}/codecvt.h \
+	${bits_srcdir}/concept_check.h \
+	${bits_srcdir}/cpp_type_traits.h \
+	${bits_srcdir}/deque.tcc \
+	${bits_srcdir}/enable_special_members.h \
+	${bits_srcdir}/erase_if.h \
+	${bits_srcdir}/forward_list.h \
+	${bits_srcdir}/forward_list.tcc \
+	${bits_srcdir}/fs_dir.h \
+	${bits_srcdir}/fs_fwd.h \
+	${bits_srcdir}/fs_ops.h \
+	${bits_srcdir}/fs_path.h \
+	${bits_srcdir}/fstream.tcc \
+	${bits_srcdir}/functexcept.h \
+	${bits_srcdir}/functional_hash.h \
+	${bits_srcdir}/gslice.h \
+	${bits_srcdir}/gslice_array.h \
+	${bits_srcdir}/hashtable.h \
+	${bits_srcdir}/hashtable_policy.h \
+	${bits_srcdir}/indirect_array.h \
+	${bits_srcdir}/invoke.h \
+	${bits_srcdir}/ios_base.h \
+	${bits_srcdir}/istream.tcc \
+	${bits_srcdir}/iterator_concepts.h \
+	${bits_srcdir}/list.tcc \
+	${bits_srcdir}/locale_classes.h \
+	${bits_srcdir}/locale_classes.tcc \
+	${bits_srcdir}/locale_conv.h \
+	${bits_srcdir}/locale_facets.h \
+	${bits_srcdir}/locale_facets.tcc \
+	${bits_srcdir}/locale_facets_nonio.h \
+	${bits_srcdir}/locale_facets_nonio.tcc \
+	${bits_srcdir}/localefwd.h \
+	${bits_srcdir}/mask_array.h \
+	${bits_srcdir}/memoryfwd.h \
+	${bits_srcdir}/move.h \
+	${bits_srcdir}/node_handle.h \
+	${bits_srcdir}/ostream.tcc \
+	${bits_srcdir}/ostream_insert.h \
+	${bits_srcdir}/parse_numbers.h \
+	${bits_srcdir}/postypes.h \
+	${bits_srcdir}/predefined_ops.h \
+	${bits_srcdir}/ptr_traits.h \
+	${bits_srcdir}/quoted_string.h \
+	${bits_srcdir}/random.h \
+	${bits_srcdir}/random.tcc \
+	${bits_srcdir}/range_access.h \
+	${bits_srcdir}/range_cmp.h \
+	${bits_srcdir}/refwrap.h \
+	${bits_srcdir}/regex.h \
+	${bits_srcdir}/regex.tcc \
+	${bits_srcdir}/regex_constants.h \
+	${bits_srcdir}/regex_error.h \
+	${bits_srcdir}/regex_scanner.h \
+	${bits_srcdir}/regex_scanner.tcc \
+	${bits_srcdir}/regex_automaton.h \
+	${bits_srcdir}/regex_automaton.tcc \
+	${bits_srcdir}/regex_compiler.h \
+	${bits_srcdir}/regex_compiler.tcc \
+	${bits_srcdir}/regex_executor.h \
+	${bits_srcdir}/regex_executor.tcc \
+	${bits_srcdir}/shared_ptr.h \
+	${bits_srcdir}/shared_ptr_atomic.h \
+	${bits_srcdir}/shared_ptr_base.h \
+	${bits_srcdir}/slice_array.h \
+	${bits_srcdir}/specfun.h \
+	${bits_srcdir}/sstream.tcc \
+	${bits_srcdir}/std_abs.h \
+	${bits_srcdir}/std_function.h \
+	${bits_srcdir}/std_mutex.h \
+	${bits_srcdir}/stl_algo.h \
+	${bits_srcdir}/stl_algobase.h \
+	${bits_srcdir}/stl_bvector.h \
+	${bits_srcdir}/stl_construct.h \
+	${bits_srcdir}/stl_deque.h \
+	${bits_srcdir}/stl_function.h \
+	${bits_srcdir}/stl_heap.h \
+	${bits_srcdir}/stl_iterator.h \
+	${bits_srcdir}/stl_iterator_base_funcs.h \
+	${bits_srcdir}/stl_iterator_base_types.h \
+	${bits_srcdir}/stl_list.h \
+	${bits_srcdir}/stl_map.h \
+	${bits_srcdir}/stl_multimap.h \
+	${bits_srcdir}/stl_multiset.h \
+	${bits_srcdir}/stl_numeric.h \
+	${bits_srcdir}/stl_pair.h \
+	${bits_srcdir}/stl_queue.h \
+	${bits_srcdir}/stl_raw_storage_iter.h \
+	${bits_srcdir}/stl_relops.h \
+	${bits_srcdir}/stl_set.h \
+	${bits_srcdir}/stl_stack.h \
+	${bits_srcdir}/stl_tempbuf.h \
+	${bits_srcdir}/stl_tree.h \
+	${bits_srcdir}/stl_uninitialized.h \
+	${bits_srcdir}/stl_vector.h \
+	${bits_srcdir}/stream_iterator.h \
+	${bits_srcdir}/streambuf_iterator.h \
+	${bits_srcdir}/streambuf.tcc \
+	${bits_srcdir}/stringfwd.h \
+	${bits_srcdir}/string_view.tcc \
+	${bits_srcdir}/uniform_int_dist.h \
+	${bits_srcdir}/unique_lock.h \
+	${bits_srcdir}/unique_ptr.h \
+	${bits_srcdir}/unordered_map.h \
+	${bits_srcdir}/unordered_set.h \
+	${bits_srcdir}/uses_allocator.h \
+	${bits_srcdir}/valarray_array.h \
+	${bits_srcdir}/valarray_array.tcc \
+	${bits_srcdir}/valarray_before.h \
+	${bits_srcdir}/valarray_after.h \
+	${bits_srcdir}/vector.tcc
+
+bits_host_headers = \
+	${glibcxx_srcdir}/${CPU_OPT_BITS_RANDOM}
+
+bits_sup_srcdir = ${glibcxx_srcdir}/libsupc++
+bits_sup_headers = \
+	${bits_sup_srcdir}/atomic_lockfree_defines.h \
+	${bits_sup_srcdir}/cxxabi_forced.h \
+	${bits_sup_srcdir}/cxxabi_init_exception.h \
+	${bits_sup_srcdir}/exception.h \
+	${bits_sup_srcdir}/exception_defines.h \
+	${bits_sup_srcdir}/exception_ptr.h \
+	${bits_sup_srcdir}/hash_bytes.h \
+	${bits_sup_srcdir}/nested_exception.h
+
+
+# C++17 Parallel Algorithm Includes.
+pstl_srcdir = ${glibcxx_srcdir}/include/pstl
+pstl_builddir = ./pstl
+pstl_headers = \
+	${pstl_srcdir}/algorithm_fwd.h \
+	${pstl_srcdir}/algorithm_impl.h \
+	${pstl_srcdir}/execution_defs.h \
+	${pstl_srcdir}/execution_impl.h \
+	${pstl_srcdir}/glue_algorithm_defs.h \
+	${pstl_srcdir}/glue_algorithm_impl.h \
+	${pstl_srcdir}/glue_execution_defs.h \
+	${pstl_srcdir}/glue_memory_defs.h \
+	${pstl_srcdir}/glue_memory_impl.h \
+	${pstl_srcdir}/glue_numeric_defs.h \
+	${pstl_srcdir}/glue_numeric_impl.h \
+	${pstl_srcdir}/memory_impl.h \
+	${pstl_srcdir}/numeric_fwd.h \
+	${pstl_srcdir}/numeric_impl.h \
+	${pstl_srcdir}/parallel_backend.h \
+	${pstl_srcdir}/parallel_backend_tbb.h \
+	${pstl_srcdir}/parallel_backend_serial.h \
+	${pstl_srcdir}/parallel_backend_utils.h \
+	${pstl_srcdir}/parallel_impl.h \
+	${pstl_srcdir}/pstl_config.h \
+	${pstl_srcdir}/unseq_backend_simd.h \
+	${pstl_srcdir}/utils.h
+
+backward_srcdir = ${glibcxx_srcdir}/include/backward
+backward_builddir = ./backward
+backward_headers = \
+	${backward_srcdir}/auto_ptr.h \
+	${backward_srcdir}/backward_warning.h \
+	${backward_srcdir}/binders.h \
+	${backward_srcdir}/hash_map \
+	${backward_srcdir}/hash_set \
+	${backward_srcdir}/hash_fun.h \
+	${backward_srcdir}/hashtable.h \
+	${backward_srcdir}/strstream
+
+pb_srcdir = ${glibcxx_srcdir}/include/ext/pb_ds
+pb_builddir = ./ext/pb_ds
+pb_subdirs = \
+	${pb_builddir}/detail \
+	${pb_builddir}/detail/pairing_heap_ \
+	${pb_builddir}/detail/splay_tree_ \
+	${pb_builddir}/detail/list_update_map_ \
+	${pb_builddir}/detail/branch_policy \
+	${pb_builddir}/detail/trie_policy \
+	${pb_builddir}/detail/gp_hash_table_map_ \
+	${pb_builddir}/detail/tree_policy \
+	${pb_builddir}/detail/binomial_heap_base_ \
+	${pb_builddir}/detail/resize_policy \
+	${pb_builddir}/detail/bin_search_tree_ \
+	${pb_builddir}/detail/binomial_heap_ \
+	${pb_builddir}/detail/thin_heap_ \
+	${pb_builddir}/detail/pat_trie_ \
+	${pb_builddir}/detail/cc_hash_table_map_ \
+	${pb_builddir}/detail/rc_binomial_heap_ \
+	${pb_builddir}/detail/left_child_next_sibling_heap_ \
+	${pb_builddir}/detail/unordered_iterator \
+	${pb_builddir}/detail/binary_heap_ \
+	${pb_builddir}/detail/ov_tree_map_ \
+	${pb_builddir}/detail/hash_fn \
+	${pb_builddir}/detail/eq_fn \
+	${pb_builddir}/detail/rb_tree_map_ \
+	${pb_builddir}/detail/list_update_policy
+
+
+# The ability for make and the underlying host to deal with this
+# unwieldy list as one entire entity is not a sure thing, and may
+# cause build errors. Thus, split one list into many smaller
+# mini-lists, with the maximum size per mini-list of no more than 42.
+pb_headers1 = \
+	${pb_srcdir}/assoc_container.hpp \
+	${pb_srcdir}/exception.hpp \
+	${pb_srcdir}/hash_policy.hpp \
+	${pb_srcdir}/list_update_policy.hpp \
+	${pb_srcdir}/priority_queue.hpp \
+	${pb_srcdir}/tag_and_trait.hpp \
+	${pb_srcdir}/tree_policy.hpp \
+	${pb_srcdir}/trie_policy.hpp \
+	${pb_srcdir}/detail/branch_policy/branch_policy.hpp \
+	${pb_srcdir}/detail/branch_policy/null_node_metadata.hpp \
+	${pb_srcdir}/detail/branch_policy/traits.hpp \
+	${pb_srcdir}/detail/binary_heap_/binary_heap_.hpp \
+	${pb_srcdir}/detail/binary_heap_/const_iterator.hpp \
+	${pb_srcdir}/detail/binary_heap_/point_const_iterator.hpp \
+	${pb_srcdir}/detail/binary_heap_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/binary_heap_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/binary_heap_/entry_cmp.hpp \
+	${pb_srcdir}/detail/binary_heap_/entry_pred.hpp \
+	${pb_srcdir}/detail/binary_heap_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/binary_heap_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/binary_heap_/info_fn_imps.hpp \
+	${pb_srcdir}/detail/binary_heap_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/binary_heap_/iterators_fn_imps.hpp \
+	${pb_srcdir}/detail/binary_heap_/policy_access_fn_imps.hpp \
+	${pb_srcdir}/detail/binary_heap_/resize_policy.hpp \
+	${pb_srcdir}/detail/binary_heap_/split_join_fn_imps.hpp \
+	${pb_srcdir}/detail/binary_heap_/trace_fn_imps.hpp \
+	${pb_srcdir}/detail/binomial_heap_base_/binomial_heap_base_.hpp \
+	${pb_srcdir}/detail/binomial_heap_base_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/binomial_heap_base_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/binomial_heap_base_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/binomial_heap_base_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/binomial_heap_base_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/binomial_heap_base_/split_join_fn_imps.hpp \
+	${pb_srcdir}/detail/binomial_heap_/binomial_heap_.hpp \
+	${pb_srcdir}/detail/binomial_heap_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/binomial_heap_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/bin_search_tree_.hpp
+
+pb_headers2 = \
+	${pb_srcdir}/detail/bin_search_tree_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/info_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/iterators_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/node_iterators.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/point_iterators.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/policy_access_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/r_erase_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/rotate_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/split_join_fn_imps.hpp \
+	${pb_srcdir}/detail/bin_search_tree_/traits.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/cc_ht_map_.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/cmp_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/cond_key_dtor_entry_dealtor.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/constructor_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/constructor_destructor_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/constructor_destructor_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/debug_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/debug_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/entry_list_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/erase_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/erase_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/find_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/info_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/insert_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/insert_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/iterators_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/policy_access_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/resize_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/resize_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/resize_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/cc_hash_table_map_/size_fn_imps.hpp
+
+pb_headers3 = \
+	${pb_srcdir}/detail/cc_hash_table_map_/trace_fn_imps.hpp \
+	${pb_srcdir}/detail/cond_dealtor.hpp \
+	${pb_srcdir}/detail/container_base_dispatch.hpp \
+	${pb_srcdir}/detail/eq_fn/eq_by_less.hpp \
+	${pb_srcdir}/detail/eq_fn/hash_eq_fn.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/constructor_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/constructor_destructor_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/constructor_destructor_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/debug_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/debug_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/erase_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/erase_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/find_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/find_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/gp_ht_map_.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/info_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/insert_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/insert_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/iterator_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/policy_access_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/resize_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/resize_no_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/resize_store_hash_fn_imps.hpp \
+	${pb_srcdir}/detail/gp_hash_table_map_/trace_fn_imps.hpp \
+	${pb_srcdir}/detail/hash_fn/direct_mask_range_hashing_imp.hpp \
+	${pb_srcdir}/detail/hash_fn/direct_mod_range_hashing_imp.hpp \
+	${pb_srcdir}/detail/hash_fn/linear_probe_fn_imp.hpp \
+	${pb_srcdir}/detail/hash_fn/mask_based_range_hashing.hpp \
+	${pb_srcdir}/detail/hash_fn/mod_based_range_hashing.hpp \
+	${pb_srcdir}/detail/hash_fn/probe_fn_base.hpp \
+	${pb_srcdir}/detail/hash_fn/quadratic_probe_fn_imp.hpp \
+	${pb_srcdir}/detail/hash_fn/ranged_hash_fn.hpp \
+	${pb_srcdir}/detail/hash_fn/ranged_probe_fn.hpp
+
+pb_headers4 = \
+	${pb_srcdir}/detail/hash_fn/sample_probe_fn.hpp \
+	${pb_srcdir}/detail/hash_fn/sample_ranged_hash_fn.hpp \
+	${pb_srcdir}/detail/hash_fn/sample_ranged_probe_fn.hpp \
+	${pb_srcdir}/detail/hash_fn/sample_range_hashing.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/const_iterator.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/point_const_iterator.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/info_fn_imps.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/iterators_fn_imps.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/left_child_next_sibling_heap_.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/node.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/policy_access_fn_imps.hpp \
+	${pb_srcdir}/detail/left_child_next_sibling_heap_/trace_fn_imps.hpp \
+	${pb_srcdir}/detail/list_update_map_/constructor_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/list_update_map_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/list_update_map_/entry_metadata_base.hpp \
+	${pb_srcdir}/detail/list_update_map_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/list_update_map_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/list_update_map_/info_fn_imps.hpp \
+	${pb_srcdir}/detail/list_update_map_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/list_update_map_/iterators_fn_imps.hpp \
+	${pb_srcdir}/detail/list_update_map_/lu_map_.hpp \
+	${pb_srcdir}/detail/list_update_map_/trace_fn_imps.hpp \
+	${pb_srcdir}/detail/list_update_policy/lu_counter_metadata.hpp \
+	${pb_srcdir}/detail/list_update_policy/sample_update_policy.hpp \
+	${pb_srcdir}/detail/debug_map_base.hpp \
+	${pb_srcdir}/detail/ov_tree_map_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/ov_tree_map_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/ov_tree_map_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/ov_tree_map_/info_fn_imps.hpp \
+	${pb_srcdir}/detail/ov_tree_map_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/ov_tree_map_/iterators_fn_imps.hpp \
+	${pb_srcdir}/detail/ov_tree_map_/node_iterators.hpp \
+	${pb_srcdir}/detail/ov_tree_map_/ov_tree_map_.hpp
+
+pb_headers5 = \
+	${pb_srcdir}/detail/ov_tree_map_/policy_access_fn_imps.hpp \
+	${pb_srcdir}/detail/ov_tree_map_/split_join_fn_imps.hpp \
+	${pb_srcdir}/detail/ov_tree_map_/traits.hpp \
+	${pb_srcdir}/detail/pairing_heap_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/pairing_heap_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/pairing_heap_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/pairing_heap_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/pairing_heap_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/pairing_heap_/pairing_heap_.hpp \
+	${pb_srcdir}/detail/pairing_heap_/split_join_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/info_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/insert_join_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/iterators_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/pat_trie_.hpp \
+	${pb_srcdir}/detail/pat_trie_/pat_trie_base.hpp \
+	${pb_srcdir}/detail/pat_trie_/policy_access_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/r_erase_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/rotate_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/split_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/synth_access_traits.hpp \
+	${pb_srcdir}/detail/pat_trie_/trace_fn_imps.hpp \
+	${pb_srcdir}/detail/pat_trie_/traits.hpp \
+	${pb_srcdir}/detail/pat_trie_/update_fn_imps.hpp \
+	${pb_srcdir}/detail/priority_queue_base_dispatch.hpp \
+	${pb_srcdir}/detail/rb_tree_map_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/rb_tree_map_/debug_fn_imps.hpp
+
+pb_headers6 = \
+	${pb_srcdir}/detail/rb_tree_map_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/rb_tree_map_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/rb_tree_map_/info_fn_imps.hpp \
+	${pb_srcdir}/detail/rb_tree_map_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/rb_tree_map_/node.hpp \
+	${pb_srcdir}/detail/rb_tree_map_/rb_tree_.hpp \
+	${pb_srcdir}/detail/rb_tree_map_/split_join_fn_imps.hpp \
+	${pb_srcdir}/detail/rb_tree_map_/traits.hpp \
+	${pb_srcdir}/detail/rc_binomial_heap_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/rc_binomial_heap_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/rc_binomial_heap_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/rc_binomial_heap_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/rc_binomial_heap_/rc_binomial_heap_.hpp \
+	${pb_srcdir}/detail/rc_binomial_heap_/rc.hpp \
+	${pb_srcdir}/detail/rc_binomial_heap_/split_join_fn_imps.hpp \
+	${pb_srcdir}/detail/rc_binomial_heap_/trace_fn_imps.hpp \
+	${pb_srcdir}/detail/resize_policy/cc_hash_max_collision_check_resize_trigger_imp.hpp \
+	${pb_srcdir}/detail/resize_policy/hash_exponential_size_policy_imp.hpp \
+	${pb_srcdir}/detail/resize_policy/hash_load_check_resize_trigger_imp.hpp \
+	${pb_srcdir}/detail/resize_policy/hash_load_check_resize_trigger_size_base.hpp \
+	${pb_srcdir}/detail/resize_policy/hash_prime_size_policy_imp.hpp \
+	${pb_srcdir}/detail/resize_policy/hash_standard_resize_policy_imp.hpp \
+	${pb_srcdir}/detail/resize_policy/sample_resize_policy.hpp \
+	${pb_srcdir}/detail/resize_policy/sample_resize_trigger.hpp \
+	${pb_srcdir}/detail/resize_policy/sample_size_policy.hpp \
+	${pb_srcdir}/detail/splay_tree_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/splay_tree_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/splay_tree_/erase_fn_imps.hpp \
+	${pb_srcdir}/detail/splay_tree_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/splay_tree_/info_fn_imps.hpp \
+	${pb_srcdir}/detail/splay_tree_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/splay_tree_/node.hpp \
+	${pb_srcdir}/detail/splay_tree_/splay_fn_imps.hpp \
+	${pb_srcdir}/detail/splay_tree_/splay_tree_.hpp \
+	${pb_srcdir}/detail/splay_tree_/split_join_fn_imps.hpp \
+	${pb_srcdir}/detail/splay_tree_/traits.hpp \
+	${pb_srcdir}/detail/standard_policies.hpp \
+	${pb_srcdir}/detail/thin_heap_/constructors_destructor_fn_imps.hpp \
+	${pb_srcdir}/detail/thin_heap_/debug_fn_imps.hpp \
+	${pb_srcdir}/detail/thin_heap_/erase_fn_imps.hpp
+
+pb_headers7 = \
+	${pb_srcdir}/detail/thin_heap_/find_fn_imps.hpp \
+	${pb_srcdir}/detail/thin_heap_/insert_fn_imps.hpp \
+	${pb_srcdir}/detail/thin_heap_/split_join_fn_imps.hpp \
+	${pb_srcdir}/detail/thin_heap_/thin_heap_.hpp \
+	${pb_srcdir}/detail/thin_heap_/trace_fn_imps.hpp \
+	${pb_srcdir}/detail/tree_policy/node_metadata_selector.hpp \
+	${pb_srcdir}/detail/tree_policy/order_statistics_imp.hpp \
+	${pb_srcdir}/detail/tree_policy/sample_tree_node_update.hpp \
+	${pb_srcdir}/detail/tree_trace_base.hpp \
+	${pb_srcdir}/detail/trie_policy/node_metadata_selector.hpp \
+	${pb_srcdir}/detail/trie_policy/order_statistics_imp.hpp \
+	${pb_srcdir}/detail/trie_policy/prefix_search_node_update_imp.hpp \
+	${pb_srcdir}/detail/trie_policy/sample_trie_access_traits.hpp \
+	${pb_srcdir}/detail/trie_policy/sample_trie_node_update.hpp \
+	${pb_srcdir}/detail/trie_policy/trie_string_access_traits_imp.hpp \
+	${pb_srcdir}/detail/trie_policy/trie_policy_base.hpp \
+	${pb_srcdir}/detail/types_traits.hpp \
+	${pb_srcdir}/detail/type_utils.hpp \
+	${pb_srcdir}/detail/unordered_iterator/const_iterator.hpp \
+	${pb_srcdir}/detail/unordered_iterator/point_const_iterator.hpp \
+	${pb_srcdir}/detail/unordered_iterator/iterator.hpp \
+	${pb_srcdir}/detail/unordered_iterator/point_iterator.hpp
+
+ext_srcdir = ${glibcxx_srcdir}/include/ext
+ext_builddir = ./ext
+ext_headers = \
+	${ext_srcdir}/algorithm \
+	${ext_srcdir}/aligned_buffer.h \
+	${ext_srcdir}/alloc_traits.h \
+	${ext_srcdir}/atomicity.h \
+	${ext_srcdir}/bitmap_allocator.h \
+	${ext_srcdir}/cast.h \
+	${ext_srcdir}/cmath \
+	${ext_srcdir}/codecvt_specializations.h \
+	${ext_srcdir}/concurrence.h \
+	${ext_srcdir}/debug_allocator.h \
+	${ext_srcdir}/enc_filebuf.h \
+	${ext_srcdir}/extptr_allocator.h \
+	${ext_srcdir}/stdio_filebuf.h \
+	${ext_srcdir}/stdio_sync_filebuf.h \
+	${ext_srcdir}/functional \
+	${ext_srcdir}/iterator \
+	${ext_srcdir}/malloc_allocator.h \
+	${ext_srcdir}/memory \
+	${ext_srcdir}/mt_allocator.h \
+	${ext_srcdir}/new_allocator.h \
+	${ext_srcdir}/numeric \
+	${ext_srcdir}/numeric_traits.h \
+	${ext_srcdir}/pod_char_traits.h \
+	${ext_srcdir}/pointer.h \
+	${ext_srcdir}/pool_allocator.h \
+	${ext_srcdir}/rb_tree \
+	${ext_srcdir}/random \
+	${ext_srcdir}/random.tcc \
+	${ext_srcdir}/rope \
+	${ext_srcdir}/ropeimpl.h \
+	${ext_srcdir}/slist \
+	${ext_srcdir}/string_conversions.h \
+	${ext_srcdir}/throw_allocator.h \
+	${ext_srcdir}/typelist.h \
+	${ext_srcdir}/type_traits.h \
+	${ext_srcdir}/rc_string_base.h \
+	${ext_srcdir}/sso_string_base.h \
+	${ext_srcdir}/vstring.h \
+	${ext_srcdir}/vstring.tcc \
+	${ext_srcdir}/vstring_fwd.h \
+	${ext_srcdir}/vstring_util.h \
+	${ext_compat_headers}
+
+ext_compat_headers = \
+	${backward_srcdir}/hash_set \
+	${backward_srcdir}/hash_map
+
+ext_host_headers = \
+	${glibcxx_srcdir}/${CPU_OPT_EXT_RANDOM}
+
+tr1_srcdir = ${glibcxx_srcdir}/include/tr1
+tr1_builddir = ./tr1
+tr1_headers = \
+	${tr1_srcdir}/array \
+	${tr1_srcdir}/bessel_function.tcc \
+	${tr1_srcdir}/beta_function.tcc \
+	${tr1_srcdir}/ccomplex \
+	${tr1_srcdir}/cctype \
+	${tr1_srcdir}/cfenv \
+	${tr1_srcdir}/cfloat \
+	${tr1_srcdir}/cinttypes \
+	${tr1_srcdir}/climits \
+	${tr1_srcdir}/cmath \
+	${tr1_srcdir}/complex \
+	${tr1_srcdir}/complex.h \
+	${tr1_srcdir}/cstdarg \
+	${tr1_srcdir}/cstdbool \
+	${tr1_srcdir}/cstdint \
+	${tr1_srcdir}/cstdio \
+	${tr1_srcdir}/cstdlib \
+	${tr1_srcdir}/ctgmath \
+	${tr1_srcdir}/ctime \
+	${tr1_srcdir}/ctype.h \
+	${tr1_srcdir}/cwchar \
+	${tr1_srcdir}/cwctype \
+	${tr1_srcdir}/ell_integral.tcc \
+	${tr1_srcdir}/exp_integral.tcc \
+	${tr1_srcdir}/fenv.h \
+	${tr1_srcdir}/float.h \
+	${tr1_srcdir}/functional \
+	${tr1_srcdir}/functional_hash.h \
+	${tr1_srcdir}/gamma.tcc \
+	${tr1_srcdir}/hypergeometric.tcc \
+	${tr1_srcdir}/hashtable.h \
+	${tr1_srcdir}/hashtable_policy.h \
+	${tr1_srcdir}/inttypes.h \
+	${tr1_srcdir}/limits.h \
+	${tr1_srcdir}/math.h \
+	${tr1_srcdir}/memory \
+	${tr1_srcdir}/modified_bessel_func.tcc \
+	${tr1_srcdir}/poly_hermite.tcc \
+	${tr1_srcdir}/poly_laguerre.tcc \
+	${tr1_srcdir}/legendre_function.tcc \
+	${tr1_srcdir}/random \
+	${tr1_srcdir}/random.h \
+	${tr1_srcdir}/random.tcc \
+	${tr1_srcdir}/regex \
+	${tr1_srcdir}/riemann_zeta.tcc \
+	${tr1_srcdir}/shared_ptr.h \
+	${tr1_srcdir}/special_function_util.h \
+	${tr1_srcdir}/stdarg.h \
+	${tr1_srcdir}/stdbool.h \
+	${tr1_srcdir}/stdint.h \
+	${tr1_srcdir}/stdio.h \
+	${tr1_srcdir}/stdlib.h \
+	${tr1_srcdir}/tgmath.h \
+	${tr1_srcdir}/tuple \
+	${tr1_srcdir}/type_traits \
+	${tr1_srcdir}/unordered_map \
+	${tr1_srcdir}/unordered_map.h \
+	${tr1_srcdir}/unordered_set \
+	${tr1_srcdir}/unordered_set.h \
+	${tr1_srcdir}/utility \
+	${tr1_srcdir}/wchar.h \
+	${tr1_srcdir}/wctype.h
+
+tr2_srcdir = ${glibcxx_srcdir}/include/tr2
+tr2_builddir = ./tr2
+tr2_headers = \
+	${tr2_srcdir}/bool_set \
+	${tr2_srcdir}/bool_set.tcc \
+	${tr2_srcdir}/dynamic_bitset \
+	${tr2_srcdir}/dynamic_bitset.tcc \
+	${tr2_srcdir}/ratio \
+	${tr2_srcdir}/type_traits
+
+decimal_srcdir = ${glibcxx_srcdir}/include/decimal
+decimal_builddir = ./decimal
+decimal_headers = \
+	${decimal_srcdir}/decimal \
+	${decimal_srcdir}/decimal.h
+
+
+# Post-C++11 TS's
+experimental_srcdir = ${glibcxx_srcdir}/include/experimental
+experimental_builddir = ./experimental
+experimental_headers = \
+	${experimental_srcdir}/algorithm \
+	${experimental_srcdir}/any \
+	${experimental_srcdir}/array \
+	${experimental_srcdir}/buffer \
+	${experimental_srcdir}/chrono \
+	${experimental_srcdir}/deque \
+	${experimental_srcdir}/executor \
+	${experimental_srcdir}/forward_list \
+	${experimental_srcdir}/functional \
+	${experimental_srcdir}/internet \
+	${experimental_srcdir}/io_context \
+	${experimental_srcdir}/iterator \
+	${experimental_srcdir}/list \
+	${experimental_srcdir}/map \
+	${experimental_srcdir}/memory \
+	${experimental_srcdir}/memory_resource \
+	${experimental_srcdir}/net \
+	${experimental_srcdir}/netfwd \
+	${experimental_srcdir}/numeric \
+	${experimental_srcdir}/optional \
+	${experimental_srcdir}/propagate_const \
+	${experimental_srcdir}/random \
+	${experimental_srcdir}/ratio \
+	${experimental_srcdir}/regex \
+	${experimental_srcdir}/set \
+	${experimental_srcdir}/socket \
+	${experimental_srcdir}/source_location \
+	${experimental_srcdir}/string \
+	${experimental_srcdir}/string_view \
+	${experimental_srcdir}/system_error \
+	${experimental_srcdir}/timer \
+	${experimental_srcdir}/tuple \
+	${experimental_srcdir}/type_traits \
+	${experimental_srcdir}/unordered_map \
+	${experimental_srcdir}/unordered_set \
+	${experimental_srcdir}/utility \
+	${experimental_srcdir}/vector \
+	${experimental_filesystem_headers}
+
+experimental_bits_srcdir = ${glibcxx_srcdir}/include/experimental/bits
+experimental_bits_builddir = ./experimental/bits
+experimental_bits_headers = \
+	${experimental_bits_srcdir}/lfts_config.h \
+	${experimental_bits_srcdir}/net.h \
+	${experimental_bits_srcdir}/shared_ptr.h \
+	${experimental_bits_srcdir}/string_view.tcc \
+	${experimental_bits_filesystem_headers}
+
+@ENABLE_FILESYSTEM_TS_FALSE@experimental_filesystem_headers = 
+@ENABLE_FILESYSTEM_TS_TRUE@experimental_filesystem_headers = \
+@ENABLE_FILESYSTEM_TS_TRUE@	${experimental_srcdir}/filesystem
+
+@ENABLE_FILESYSTEM_TS_FALSE@experimental_bits_filesystem_headers = 
+@ENABLE_FILESYSTEM_TS_TRUE@experimental_bits_filesystem_headers = \
+@ENABLE_FILESYSTEM_TS_TRUE@	${experimental_bits_srcdir}/fs_dir.h \
+@ENABLE_FILESYSTEM_TS_TRUE@	${experimental_bits_srcdir}/fs_fwd.h \
+@ENABLE_FILESYSTEM_TS_TRUE@	${experimental_bits_srcdir}/fs_ops.h \
+@ENABLE_FILESYSTEM_TS_TRUE@	${experimental_bits_srcdir}/fs_path.h
+
+
+# This is the common subset of C++ files that all three "C" header models use.
+c_base_srcdir = $(C_INCLUDE_DIR)
+c_base_builddir = .
+c_base_headers = \
+	${c_base_srcdir}/cassert \
+	${c_base_srcdir}/ccomplex \
+	${c_base_srcdir}/cctype \
+	${c_base_srcdir}/cerrno \
+	${c_base_srcdir}/cfenv \
+	${c_base_srcdir}/cfloat \
+	${c_base_srcdir}/cinttypes \
+	${c_base_srcdir}/ciso646 \
+	${c_base_srcdir}/climits \
+	${c_base_srcdir}/clocale \
+	${c_base_srcdir}/cmath \
+	${c_base_srcdir}/csetjmp \
+	${c_base_srcdir}/csignal \
+	${c_base_srcdir}/cstdalign \
+	${c_base_srcdir}/cstdarg \
+	${c_base_srcdir}/cstdbool \
+	${c_base_srcdir}/cstddef \
+	${c_base_srcdir}/cstdint \
+	${c_base_srcdir}/cstdio \
+	${c_base_srcdir}/cstdlib \
+	${c_base_srcdir}/cstring \
+	${c_base_srcdir}/ctgmath \
+	${c_base_srcdir}/ctime \
+	${c_base_srcdir}/cuchar \
+	${c_base_srcdir}/cwchar \
+	${c_base_srcdir}/cwctype
+
+
+# "C" compatibility headers.
+c_compatibility_srcdir = ${glibcxx_srcdir}/include/c_compatibility
+c_compatibility_builddir = .
+@GLIBCXX_C_HEADERS_C_GLOBAL_TRUE@c_compatibility_headers = \
+@GLIBCXX_C_HEADERS_C_GLOBAL_TRUE@	${c_compatibility_srcdir}/complex.h \
+@GLIBCXX_C_HEADERS_C_GLOBAL_TRUE@	${c_compatibility_srcdir}/fenv.h \
+@GLIBCXX_C_HEADERS_C_GLOBAL_TRUE@	${c_compatibility_srcdir}/tgmath.h \
+@GLIBCXX_C_HEADERS_C_GLOBAL_TRUE@	${c_compatibility_srcdir}/math.h \
+@GLIBCXX_C_HEADERS_C_GLOBAL_TRUE@	${c_compatibility_srcdir}/stdlib.h
+
+@GLIBCXX_C_HEADERS_C_STD_TRUE@c_compatibility_headers = 
+@GLIBCXX_C_HEADERS_C_TRUE@c_compatibility_headers = \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/assert.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/complex.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/ctype.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/errno.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/fenv.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/float.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/inttypes.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/iso646.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/limits.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/locale.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/math.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/setjmp.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/signal.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/stdarg.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/stdbool.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/stddef.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/stdint.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/stdio.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/stdlib.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/string.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/tgmath.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/time.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/uchar.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/wchar.h \
+@GLIBCXX_C_HEADERS_C_TRUE@	${c_compatibility_srcdir}/wctype.h
+
+
+# Debug mode headers
+debug_srcdir = ${glibcxx_srcdir}/include/debug
+debug_builddir = ./debug
+debug_headers = \
+	${debug_srcdir}/array \
+	${debug_srcdir}/assertions.h \
+	${debug_srcdir}/bitset \
+	${debug_srcdir}/debug.h \
+	${debug_srcdir}/deque \
+	${debug_srcdir}/formatter.h \
+	${debug_srcdir}/forward_list \
+	${debug_srcdir}/functions.h \
+	${debug_srcdir}/helper_functions.h \
+	${debug_srcdir}/list \
+	${debug_srcdir}/map \
+	${debug_srcdir}/macros.h \
+	${debug_srcdir}/map.h \
+	${debug_srcdir}/multimap.h \
+	${debug_srcdir}/multiset.h \
+	${debug_srcdir}/safe_base.h \
+	${debug_srcdir}/safe_container.h \
+	${debug_srcdir}/safe_iterator.h \
+	${debug_srcdir}/safe_iterator.tcc \
+	${debug_srcdir}/safe_local_iterator.h \
+	${debug_srcdir}/safe_local_iterator.tcc \
+	${debug_srcdir}/safe_sequence.h \
+	${debug_srcdir}/safe_sequence.tcc \
+	${debug_srcdir}/safe_unordered_base.h \
+	${debug_srcdir}/safe_unordered_container.h \
+	${debug_srcdir}/safe_unordered_container.tcc \
+	${debug_srcdir}/set \
+	${debug_srcdir}/set.h \
+	${debug_srcdir}/stl_iterator.h \
+	${debug_srcdir}/string \
+	${debug_srcdir}/unordered_map \
+	${debug_srcdir}/unordered_set \
+	${debug_srcdir}/vector
+
+
+# Parallel mode headers
+parallel_srcdir = ${glibcxx_srcdir}/include/parallel
+parallel_builddir = ./parallel
+parallel_headers = \
+	${parallel_srcdir}/algo.h \
+	${parallel_srcdir}/algobase.h \
+	${parallel_srcdir}/algorithm \
+	${parallel_srcdir}/algorithmfwd.h \
+	${parallel_srcdir}/balanced_quicksort.h \
+	${parallel_srcdir}/base.h \
+	${parallel_srcdir}/basic_iterator.h \
+	${parallel_srcdir}/checkers.h \
+	${parallel_srcdir}/compatibility.h \
+	${parallel_srcdir}/compiletime_settings.h \
+	${parallel_srcdir}/equally_split.h \
+	${parallel_srcdir}/features.h \
+	${parallel_srcdir}/find.h \
+	${parallel_srcdir}/find_selectors.h \
+	${parallel_srcdir}/for_each.h \
+	${parallel_srcdir}/for_each_selectors.h \
+	${parallel_srcdir}/iterator.h \
+	${parallel_srcdir}/list_partition.h \
+	${parallel_srcdir}/losertree.h \
+	${parallel_srcdir}/merge.h \
+	${parallel_srcdir}/multiseq_selection.h \
+	${parallel_srcdir}/multiway_merge.h \
+	${parallel_srcdir}/multiway_mergesort.h \
+	${parallel_srcdir}/numeric \
+	${parallel_srcdir}/numericfwd.h \
+	${parallel_srcdir}/omp_loop.h \
+	${parallel_srcdir}/omp_loop_static.h \
+	${parallel_srcdir}/par_loop.h \
+	${parallel_srcdir}/parallel.h \
+	${parallel_srcdir}/partial_sum.h \
+	${parallel_srcdir}/partition.h \
+	${parallel_srcdir}/queue.h \
+	${parallel_srcdir}/quicksort.h \
+	${parallel_srcdir}/random_number.h \
+	${parallel_srcdir}/random_shuffle.h \
+	${parallel_srcdir}/search.h \
+	${parallel_srcdir}/set_operations.h \
+	${parallel_srcdir}/settings.h \
+	${parallel_srcdir}/sort.h \
+	${parallel_srcdir}/tags.h \
+	${parallel_srcdir}/types.h \
+	${parallel_srcdir}/unique_copy.h \
+	${parallel_srcdir}/workstealing.h
+
+@GLIBCXX_C_HEADERS_COMPATIBILITY_FALSE@c_compatibility_headers_extra = 
+
+# Some "C" header schemes require the "C" compatibility headers.
+# For --enable-cheaders=c_std
+@GLIBCXX_C_HEADERS_COMPATIBILITY_TRUE@c_compatibility_headers_extra = ${c_compatibility_headers}
+host_srcdir = ${glibcxx_srcdir}/$(OS_INC_SRCDIR)
+host_builddir = ./${host_alias}/bits
+host_installdir = ${gxx_include_dir}/${host_alias}$(MULTISUBDIR)/bits
+host_headers = \
+	${host_srcdir}/ctype_base.h \
+	${host_srcdir}/ctype_inline.h \
+	${host_srcdir}/os_defines.h \
+	${glibcxx_srcdir}/$(ATOMIC_WORD_SRCDIR)/atomic_word.h \
+	${glibcxx_srcdir}/$(ABI_TWEAKS_SRCDIR)/cxxabi_tweaks.h \
+	${glibcxx_srcdir}/$(CPU_DEFINES_SRCDIR)/cpu_defines.h \
+	${glibcxx_srcdir}/$(ERROR_CONSTANTS_SRCDIR)/error_constants.h \
+	${glibcxx_srcdir}/include/precompiled/stdc++.h \
+	${glibcxx_srcdir}/include/precompiled/stdtr1c++.h \
+	${glibcxx_srcdir}/include/precompiled/extc++.h
+
+
+# Non-installed host_header files.
+COMPATIBILITY_H = config/abi/compatibility.h
+host_headers_noinst = \
+	${glibcxx_srcdir}/$(CLOCALE_INTERNAL_H) \
+	${glibcxx_srcdir}/$(COMPATIBILITY_H)
+
+
+# These host_headers_extra files are all built with ad hoc naming rules.
+host_headers_extra = \
+	${host_builddir}/basic_file.h \
+	${host_builddir}/c++config.h \
+	${host_builddir}/c++allocator.h \
+	${host_builddir}/c++io.h \
+	${host_builddir}/c++locale.h \
+	${host_builddir}/messages_members.h \
+	${host_builddir}/time_members.h
+
+thread_host_headers = \
+	${host_builddir}/gthr.h \
+	${host_builddir}/gthr-single.h \
+	${host_builddir}/gthr-posix.h \
+	${host_builddir}/gthr-default.h
+
+pch1_source = ${glibcxx_srcdir}/include/precompiled/stdc++.h
+pch1_output_builddir = ${host_builddir}/stdc++.h.gch
+pch1_output_anchor = ${host_builddir}/stdc++.h
+pch1_output_installdir = ${host_installdir}/stdc++.h.gch
+pch1a_output = ${pch1_output_builddir}/O2ggnu++0x.gch
+pch1b_output = ${pch1_output_builddir}/O2g.gch
+pch1_output = ${pch1a_output} ${pch1b_output}
+pch2_source = ${glibcxx_srcdir}/include/precompiled/stdtr1c++.h
+pch2_output_builddir = ${host_builddir}/stdtr1c++.h.gch
+pch2_output_anchor = ${host_builddir}/stdtr1c++.h
+pch2_output_installdir = ${host_installdir}/stdtr1c++.h.gch
+pch2_output = ${pch2_output_builddir}/O2g.gch
+pch3_source = ${glibcxx_srcdir}/include/precompiled/extc++.h
+pch3_output_builddir = ${host_builddir}/extc++.h.gch
+pch3_output_anchor = ${host_builddir}/extc++.h
+pch3_output_installdir = ${host_installdir}/extc++.h.gch
+pch3_output = ${pch3_output_builddir}/O2g.gch
+pch_output = ${pch1_output} ${pch2_output} ${pch3_output}
+pch_output_dirs = \
+	${pch1_output_builddir} ${pch2_output_builddir} ${pch3_output_builddir}
+
+pch_output_anchors = \
+	${pch1_output_anchor} ${pch2_output_anchor} ${pch3_output_anchor}
+
+PCHFLAGS = -x c++-header -nostdinc++ $(CXXFLAGS) $(VTV_PCH_CXXFLAGS)
+@GLIBCXX_BUILD_PCH_FALSE@pch_build = 
+@GLIBCXX_BUILD_PCH_TRUE@pch_build = ${pch_output}
+
+# List of all timestamp files.  By keeping only one copy of this list, both
+# CLEANFILES and all-local are kept up-to-date.
+allstamped = \
+	stamp-std stamp-bits stamp-bits-sup stamp-pstl stamp-c_base stamp-c_compatibility \
+	stamp-backward stamp-ext stamp-pb stamp-tr1 stamp-tr2 stamp-decimal \
+	stamp-experimental stamp-experimental-bits stamp-debug stamp-parallel \
+	stamp-host
+
+
+# List of all files that are created by explicit building, editing, or
+# catenation.
+allcreated = \
+	${host_builddir}/c++config.h \
+	${host_builddir}/largefile-config.h \
+	${thread_host_headers} \
+	${pch_build}
+
+
+# Host includes for threads
+uppercase = [ABCDEFGHIJKLMNOPQRSTUVWXYZ_]
+# By adding these files here, automake will remove them for 'make clean'
+CLEANFILES = ${pch_output} ${pch_output_anchors} stamp-host
 @GLIBCXX_HOSTED_TRUE@hosted_source = src doc po testsuite python
 SUBDIRS = include libsupc++ $(hosted_source)
 ACLOCAL_AMFLAGS = -I . -I .. -I ../config
@@ -490,7 +1487,7 @@ all: config.h
 .SUFFIXES:
 am--refresh: Makefile
 	@:
-$(srcdir)/Makefile.in: @MAINTAINER_MODE_TRUE@ $(srcdir)/Makefile.am $(top_srcdir)/fragment.am $(top_srcdir)/../multilib.am $(am__configure_deps)
+$(srcdir)/Makefile.in: @MAINTAINER_MODE_TRUE@ $(srcdir)/Makefile.am $(top_srcdir)/fragment.am $(top_srcdir)/fragment.am $(top_srcdir)/../multilib.am $(am__configure_deps)
 	@for dep in $?; do \
 	  case '$(am__configure_deps)' in \
 	    *$$dep*) \
@@ -512,7 +1509,7 @@ Makefile: $(srcdir)/Makefile.in $(top_builddir)/config.status
 	    echo ' cd $(top_builddir) && $(SHELL) ./config.status $@ $(am__depfiles_maybe)'; \
 	    cd $(top_builddir) && $(SHELL) ./config.status $@ $(am__depfiles_maybe);; \
 	esac;
-$(top_srcdir)/fragment.am $(top_srcdir)/../multilib.am $(am__empty):
+$(top_srcdir)/fragment.am $(top_srcdir)/fragment.am $(top_srcdir)/../multilib.am $(am__empty):
 
 $(top_builddir)/config.status: $(top_srcdir)/configure $(CONFIG_STATUS_DEPENDENCIES)
 	$(SHELL) ./config.status --recheck
@@ -684,6 +1681,7 @@ install-strip:
 mostlyclean-generic:
 
 clean-generic:
+	-test -z "$(CLEANFILES)" || rm -f $(CLEANFILES)
 
 distclean-generic:
 	-test -z "$(CONFIG_CLEAN_FILES)" || rm -f $(CONFIG_CLEAN_FILES)
@@ -708,7 +1706,7 @@ html-am:
 
 info-am:
 
-install-data-am:
+install-data-am: install-data-local
 
 install-dvi-am:
 
@@ -750,18 +1748,475 @@ uninstall-am:
 	distclean distclean-generic distclean-hdr distclean-libtool \
 	distclean-local distclean-tags dvi dvi-am html html-am info \
 	info-am install install-am install-data install-data-am \
-	install-dvi install-dvi-am install-exec install-exec-am \
-	install-exec-local install-html install-html-am install-info \
-	install-info-am install-man install-pdf install-pdf-am \
-	install-ps install-ps-am install-strip installcheck \
-	installcheck-am installdirs installdirs-am maintainer-clean \
-	maintainer-clean-generic maintainer-clean-local mostlyclean \
-	mostlyclean-generic mostlyclean-libtool mostlyclean-local pdf \
-	pdf-am ps ps-am tags tags-am uninstall uninstall-am
+	install-data-local install-dvi install-dvi-am install-exec \
+	install-exec-am install-exec-local install-html \
+	install-html-am install-info install-info-am install-man \
+	install-pdf install-pdf-am install-ps install-ps-am \
+	install-strip installcheck installcheck-am installdirs \
+	installdirs-am maintainer-clean maintainer-clean-generic \
+	maintainer-clean-local mostlyclean mostlyclean-generic \
+	mostlyclean-libtool mostlyclean-local pdf pdf-am ps ps-am tags \
+	tags-am uninstall uninstall-am
 
 .PRECIOUS: Makefile
 
 
+# Here are the rules for building the headers
+all-local: ${allstamped} ${allcreated}
+
+# Ignore errors from 'mkdir -p' to avoid parallel make failure on
+# systems with broken mkdir.  Call mkdir unconditionally because
+# it is just as cheap to avoid going through the shell.
+# Ignore errors from $(LN_S) because the links may already exist.
+stamp-std: ${std_headers}
+	@-mkdir -p ${std_builddir}
+	@-cd ${std_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-std
+
+stamp-bits: ${bits_headers}
+	@-mkdir -p ${bits_builddir}
+	@-cd ${bits_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-bits
+
+stamp-bits-sup: stamp-bits ${bits_sup_headers}
+	@-cd ${bits_builddir} && $(LN_S) ${bits_sup_headers} . 2>/dev/null
+	@$(STAMP) stamp-bits-sup
+
+stamp-pstl: ${pstl_headers}
+	@-mkdir -p ${pstl_builddir}
+	@-cd ${pstl_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-pstl
+
+stamp-c_base: ${c_base_headers}
+	@-mkdir -p ${c_base_builddir}
+	@-cd ${c_base_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-c_base
+
+stamp-c_base_extra: ${c_base_headers_extra}
+	@-mkdir -p ${bits_builddir}
+	@-cd ${bits_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-c_base_extra
+
+stamp-c_compatibility: ${c_compatibility_headers_extra}
+	@-mkdir -p ${c_compatibility_builddir}
+	@-if [ ! -z "${c_compatibility_headers_extra}" ]; then \
+	  cd ${c_compatibility_builddir} && $(LN_S) $? . 2>/dev/null ;\
+	fi
+	@$(STAMP) stamp-c_compatibility
+
+stamp-backward: ${backward_headers}
+	@-mkdir -p ${backward_builddir}
+	@-cd ${backward_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-backward
+
+stamp-ext: ${ext_headers}
+	@-mkdir -p ${ext_builddir}
+	@-cd ${ext_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-ext
+
+# Have to deal with nested include directories, gah! Strip off source
+# directory before making the link.
+# XXX check  ${pb_headers}
+stamp-pb:
+	@if [ ! -d "${pb_builddir}" ]; then \
+	    mkdir -p ${pb_subdirs} ;\
+	fi
+	@if [ ! -f stamp-pb ]; then \
+	    cd ${pb_builddir} && for h in ${pb_headers1}; do \
+		build_name=`echo $$h | sed -e "s|${pb_srcdir}|.|g"` ;\
+		$(LN_S) $$h $${build_name} || true ;\
+	      done ;\
+	fi
+	@if [ ! -f stamp-pb ]; then \
+	    cd ${pb_builddir} && for h in ${pb_headers2}; do \
+		build_name=`echo $$h | sed -e "s|${pb_srcdir}|.|g"` ;\
+		$(LN_S) $$h $${build_name} || true ;\
+	      done ;\
+	fi
+	@if [ ! -f stamp-pb ]; then \
+	    cd ${pb_builddir} && for h in ${pb_headers3}; do \
+		build_name=`echo $$h | sed -e "s|${pb_srcdir}|.|g"` ;\
+		$(LN_S) $$h $${build_name} || true ;\
+	      done ;\
+	fi
+	@if [ ! -f stamp-pb ]; then \
+	    cd ${pb_builddir} && for h in ${pb_headers4}; do \
+		build_name=`echo $$h | sed -e "s|${pb_srcdir}|.|g"` ;\
+		$(LN_S) $$h $${build_name} || true ;\
+	      done ;\
+	fi
+	@if [ ! -f stamp-pb ]; then \
+	    cd ${pb_builddir} && for h in ${pb_headers5}; do \
+		build_name=`echo $$h | sed -e "s|${pb_srcdir}|.|g"` ;\
+		$(LN_S) $$h $${build_name} || true ;\
+	      done ;\
+	fi
+	@if [ ! -f stamp-pb ]; then \
+	    cd ${pb_builddir} && for h in ${pb_headers6}; do \
+		build_name=`echo $$h | sed -e "s|${pb_srcdir}|.|g"` ;\
+		$(LN_S) $$h $${build_name} || true ;\
+	      done ;\
+	fi
+	@if [ ! -f stamp-pb ]; then \
+	    cd ${pb_builddir} && for h in ${pb_headers7}; do \
+		build_name=`echo $$h | sed -e "s|${pb_srcdir}|.|g"` ;\
+		$(LN_S) $$h $${build_name} || true ;\
+	      done ;\
+	fi
+	$(STAMP) stamp-pb
+
+stamp-tr1: ${tr1_headers}
+	@-mkdir -p ${tr1_builddir}
+	@-cd ${tr1_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-tr1
+
+stamp-tr2: ${tr2_headers}
+	@-mkdir -p ${tr2_builddir}
+	@-cd ${tr2_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-tr2
+
+stamp-decimal: ${decimal_headers}
+	@-mkdir -p ${decimal_builddir}
+	@-cd ${decimal_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-decimal
+
+stamp-experimental: ${experimental_headers}
+	@-mkdir -p ${experimental_builddir}
+	@-cd ${experimental_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-experimental
+
+stamp-experimental-bits: ${experimental_bits_headers}
+	@-mkdir -p ${experimental_bits_builddir}
+	@-cd ${experimental_bits_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-experimental-bits
+
+stamp-debug: ${debug_headers}
+	@-mkdir -p ${debug_builddir}
+	@-cd ${debug_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-debug
+
+stamp-parallel: ${parallel_headers}
+	@-mkdir -p ${parallel_builddir}
+	@-cd ${parallel_builddir} && $(LN_S) $? . 2>/dev/null
+	@$(STAMP) stamp-parallel
+
+stamp-${host_alias}:
+	@-mkdir -p ${host_builddir}
+	@-mkdir -p ${host_builddir}/../ext
+	@$(STAMP) stamp-${host_alias}
+
+# Host includes static.
+# XXX Missing dependency info for {host_headers_extra}
+stamp-host: ${host_headers} ${bits_host_headers} ${ext_host_headers} ${host_headers_noinst} stamp-${host_alias}
+	@cd ${host_builddir} && {\
+	  $(LN_S) ${host_headers} ${bits_host_headers} . || true ;\
+	  $(LN_S) ${glibcxx_srcdir}/$(BASIC_FILE_H) basic_file.h || true ;\
+	  $(LN_S) ${glibcxx_srcdir}/$(ALLOCATOR_H) c++allocator.h || true ;\
+	  $(LN_S) ${glibcxx_srcdir}/$(CSTDIO_H) c++io.h || true ;\
+	  $(LN_S) ${glibcxx_srcdir}/$(CLOCALE_H) c++locale.h || true ;\
+	  $(LN_S) ${glibcxx_srcdir}/$(CLOCALE_INTERNAL_H) . || true ;\
+	  $(LN_S) ${glibcxx_srcdir}/$(COMPATIBILITY_H) . || true ;\
+	  $(LN_S) ${glibcxx_srcdir}/$(CMESSAGES_H) messages_members.h || true ;\
+	  $(LN_S) ${glibcxx_srcdir}/$(CTIME_H) time_members.h || true;\
+	} 2>/dev/null
+	@cd ${host_builddir}/../ext && {\
+	  $(LN_S) ${ext_host_headers} . || true ;\
+	} 2>/dev/null
+	$(STAMP) stamp-host
+
+# Host includes dynamic.
+@ENABLE_SYMVERS_GNU_NAMESPACE_TRUE@stamp-namespace-version:
+@ENABLE_SYMVERS_GNU_NAMESPACE_TRUE@	echo 1 > stamp-namespace-version
+@ENABLE_SYMVERS_GNU_NAMESPACE_FALSE@stamp-namespace-version:
+@ENABLE_SYMVERS_GNU_NAMESPACE_FALSE@	echo 0 > stamp-namespace-version
+
+@ENABLE_EXTERN_TEMPLATE_TRUE@stamp-extern-template:
+@ENABLE_EXTERN_TEMPLATE_TRUE@	echo 1 > stamp-extern-template
+@ENABLE_EXTERN_TEMPLATE_FALSE@stamp-extern-template:
+@ENABLE_EXTERN_TEMPLATE_FALSE@	echo 0 > stamp-extern-template
+
+@ENABLE_VISIBILITY_TRUE@stamp-visibility:
+@ENABLE_VISIBILITY_TRUE@	echo 1 > stamp-visibility
+@ENABLE_VISIBILITY_FALSE@stamp-visibility:
+@ENABLE_VISIBILITY_FALSE@	echo 0 > stamp-visibility
+
+@ENABLE_DUAL_ABI_TRUE@stamp-dual-abi:
+@ENABLE_DUAL_ABI_TRUE@	echo 1 > stamp-dual-abi
+@ENABLE_DUAL_ABI_FALSE@stamp-dual-abi:
+@ENABLE_DUAL_ABI_FALSE@	echo 0 > stamp-dual-abi
+
+@ENABLE_CXX11_ABI_TRUE@stamp-cxx11-abi:
+@ENABLE_CXX11_ABI_TRUE@	echo 1 > stamp-cxx11-abi
+@ENABLE_CXX11_ABI_FALSE@stamp-cxx11-abi:
+@ENABLE_CXX11_ABI_FALSE@	echo 0 > stamp-cxx11-abi
+
+@ENABLE_ALLOCATOR_NEW_TRUE@stamp-allocator-new:
+@ENABLE_ALLOCATOR_NEW_TRUE@	echo 1 > stamp-allocator-new
+@ENABLE_ALLOCATOR_NEW_FALSE@stamp-allocator-new:
+@ENABLE_ALLOCATOR_NEW_FALSE@	echo 0 > stamp-allocator-new
+
+@ENABLE_FLOAT128_TRUE@stamp-float128:
+@ENABLE_FLOAT128_TRUE@	echo 'define _GLIBCXX_USE_FLOAT128 1' > stamp-float128
+@ENABLE_FLOAT128_FALSE@stamp-float128:
+@ENABLE_FLOAT128_FALSE@	echo 'undef _GLIBCXX_USE_FLOAT128' > stamp-float128
+
+# This header is not installed, it's only used to build libstdc++ itself.
+${host_builddir}/largefile-config.h: ${CONFIG_HEADER}
+	@rm -f $@.tmp
+	@-grep 'define _DARWIN_USE_64_BIT_INODE' ${CONFIG_HEADER} >> $@.tmp
+	@-grep 'define _FILE_OFFSET_BITS' ${CONFIG_HEADER} >> $@.tmp
+	@-grep 'define _LARGE_FILES' ${CONFIG_HEADER} >> $@.tmp
+	@mv $@.tmp $@
+
+# NB: The non-empty default ldbl_compat works around an AIX sed
+# oddity, see libstdc++/31957 for details.
+${host_builddir}/c++config.h: ${CONFIG_HEADER} \
+			      ${glibcxx_srcdir}/include/bits/c++config \
+			      ${host_builddir}/largefile-config.h \
+			      stamp-${host_alias} \
+			      ${toplevel_srcdir}/gcc/DATESTAMP \
+			      stamp-namespace-version \
+			      stamp-visibility \
+			      stamp-extern-template \
+			      stamp-dual-abi \
+			      stamp-cxx11-abi \
+			      stamp-allocator-new \
+			      stamp-float128
+	@date=`cat ${toplevel_srcdir}/gcc/DATESTAMP` ;\
+	release=`sed 's/^\([0-9]*\).*$$/\1/' ${toplevel_srcdir}/gcc/BASE-VER` ;\
+	ns_version=`cat stamp-namespace-version` ;\
+	visibility=`cat stamp-visibility` ;\
+	externtemplate=`cat stamp-extern-template` ;\
+	dualabi=`cat stamp-dual-abi` ;\
+	cxx11abi=`cat stamp-cxx11-abi` ;\
+	allocatornew=`cat stamp-allocator-new` ;\
+	float128=`cat stamp-float128` ;\
+	ldbl_compat='s,g,g,' ;\
+	grep "^[	 ]*#[	 ]*define[	 ][	 ]*_GLIBCXX_LONG_DOUBLE_COMPAT[	 ][	 ]*1[	 ]*$$" \
+	${CONFIG_HEADER} > /dev/null 2>&1 \
+	&& ldbl_compat='s,^#undef _GLIBCXX_LONG_DOUBLE_COMPAT$$,#define _GLIBCXX_LONG_DOUBLE_COMPAT 1,' ;\
+	sed -e "s,define __GLIBCXX__,define __GLIBCXX__ $$date," \
+	-e "s,define _GLIBCXX_RELEASE,define _GLIBCXX_RELEASE $$release," \
+	-e "s,define _GLIBCXX_INLINE_VERSION, define _GLIBCXX_INLINE_VERSION $$ns_version," \
+	-e "s,define _GLIBCXX_HAVE_ATTRIBUTE_VISIBILITY, define _GLIBCXX_HAVE_ATTRIBUTE_VISIBILITY $$visibility," \
+	-e "s,define _GLIBCXX_EXTERN_TEMPLATE$$, define _GLIBCXX_EXTERN_TEMPLATE $$externtemplate," \
+	-e "s,define _GLIBCXX_USE_DUAL_ABI, define _GLIBCXX_USE_DUAL_ABI $$dualabi," \
+	-e "s,define _GLIBCXX_USE_CXX11_ABI, define _GLIBCXX_USE_CXX11_ABI $$cxx11abi," \
+	-e "s,define _GLIBCXX_USE_ALLOCATOR_NEW, define _GLIBCXX_USE_ALLOCATOR_NEW $$allocatornew," \
+	-e "s,define _GLIBCXX_USE_FLOAT128,$$float128," \
+	-e "$$ldbl_compat" \
+	    < ${glibcxx_srcdir}/include/bits/c++config > $@ ;\
+	sed -e 's/HAVE_/_GLIBCXX_HAVE_/g' \
+	    -e 's/PACKAGE/_GLIBCXX_PACKAGE/g' \
+	    -e 's/VERSION/_GLIBCXX_VERSION/g' \
+	    -e 's/WORDS_/_GLIBCXX_WORDS_/g' \
+	    -e 's/_DARWIN_USE_64_BIT_INODE/_GLIBCXX_DARWIN_USE_64_BIT_INODE/g' \
+	    -e 's/_FILE_OFFSET_BITS/_GLIBCXX_FILE_OFFSET_BITS/g' \
+	    -e 's/_LARGE_FILES/_GLIBCXX_LARGE_FILES/g' \
+	    -e 's/ICONV_CONST/_GLIBCXX_ICONV_CONST/g' \
+	    -e '/[	 ]_GLIBCXX_LONG_DOUBLE_COMPAT[	 ]/d' \
+	    < ${CONFIG_HEADER} >> $@ ;\
+	echo "" >> $@ ;\
+	echo "#endif // _GLIBCXX_CXX_CONFIG_H" >> $@
+
+${host_builddir}/gthr.h: ${toplevel_srcdir}/libgcc/gthr.h stamp-${host_alias}
+	sed -e '/^#pragma/b' \
+	    -e '/^#/s/\(${uppercase}${uppercase}*\)/_GLIBCXX_\1/g' \
+	    -e 's/_GLIBCXX_SUPPORTS_WEAK/__GXX_WEAK__/g' \
+	    -e 's/_GLIBCXX___MINGW32_GLIBCXX___/__MINGW32__/g' \
+	    -e 's,^#include "\(.*\)",#include <bits/\1>,g' \
+	    < $< > $@
+
+${host_builddir}/gthr-single.h: ${toplevel_srcdir}/libgcc/gthr-single.h \
+				  stamp-${host_alias}
+	sed -e 's/\(UNUSED\)/_GLIBCXX_\1/g' \
+	    -e 's/\(GCC${uppercase}*_H\)/_GLIBCXX_\1/g' \
+	    < $< > $@
+
+${host_builddir}/gthr-posix.h: ${toplevel_srcdir}/libgcc/gthr-posix.h \
+				   stamp-${host_alias}
+	sed -e 's/\(UNUSED\)/_GLIBCXX_\1/g' \
+	    -e 's/\(GCC${uppercase}*_H\)/_GLIBCXX_\1/g' \
+	    -e 's/SUPPORTS_WEAK/__GXX_WEAK__/g' \
+	    -e 's/\(${uppercase}*USE_WEAK\)/_GLIBCXX_\1/g' \
+	    < $< > $@
+
+${host_builddir}/gthr-default.h: ${toplevel_srcdir}/libgcc/${thread_header} \
+				   stamp-${host_alias}
+	sed -e 's/\(UNUSED\)/_GLIBCXX_\1/g' \
+	    -e 's/\(GCC${uppercase}*_H\)/_GLIBCXX_\1/g' \
+	    -e 's/SUPPORTS_WEAK/__GXX_WEAK__/g' \
+	    -e 's/\(${uppercase}*USE_WEAK\)/_GLIBCXX_\1/g' \
+	    -e 's,^#include "\(.*\)",#include <bits/\1>,g' \
+	    < $< > $@
+
+# Build two precompiled C++ includes, stdc++.h.gch/*.gch
+${pch1a_output}: ${allstamped} ${host_builddir}/c++config.h ${pch1_source}
+	-mkdir -p ${pch1_output_builddir}
+	$(CXX) $(PCHFLAGS) $(AM_CPPFLAGS) -O2 -g -std=gnu++0x ${pch1_source} \
+	-o $@
+
+${pch1b_output}: ${allstamped} ${host_builddir}/c++config.h ${pch1_source}
+	-mkdir -p ${pch1_output_builddir}
+	$(CXX) $(PCHFLAGS) $(AM_CPPFLAGS) -O2 -g ${pch1_source} -o $@
+
+# Build a precompiled TR1 include, stdtr1c++.h.gch/O2.gch
+${pch2_output}: ${pch2_source} ${pch1_output}
+	-mkdir -p ${pch2_output_builddir}
+	$(CXX) $(PCHFLAGS) $(AM_CPPFLAGS) -O2 -g ${pch2_source} -o $@
+
+# Build a precompiled extension include, extc++.h.gch/O2.gch
+${pch3_output}: ${pch3_source} ${pch2_output}
+	-mkdir -p ${pch3_output_builddir}
+	$(CXX) $(PCHFLAGS) $(AM_CPPFLAGS) -O2 -g ${pch3_source} -o $@
+
+# For robustness sake (in light of junk files or in-source
+# configuration), copy from the build or source tree to the install
+# tree using only the human-maintained file lists and directory
+# components.  Yes, with minor differences, this is sheer duplication
+# of the staging rules above using $(INSTALL_DATA) instead of LN_S and
+# `$(mkinstalldirs)' instead of `mkdir -p'.  In particular,
+# host_headers_extra are taken out of the build tree staging area;
+# the rest are taken from the original source tree.
+
+@GLIBCXX_HOSTED_TRUE@install-data-local: install-headers
+@GLIBCXX_HOSTED_FALSE@install-data-local: install-freestanding-headers
+
+# This is a subset of the full install-headers rule.  We only need <ciso646>,
+# <cstddef>, <cfloat>, <limits>, <climits>, <version>, <cstdint>, <cstdlib>,
+# <new>, <typeinfo>, <exception>, <initializer_list>, <cstdalign>, <cstdarg>,
+# <concepts>, <cstdbool>, <type_traits>, <bit>, <atomic>,
+# and any files which they include (and which we provide).
+# <new>, <typeinfo>, <exception>, <initializer_list> and <compare>
+# are installed by libsupc++, so only the others and the sub-includes
+# are copied here.
+install-freestanding-headers:
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/bits
+	for file in c++0x_warning.h atomic_base.h concept_check.h move.h; do \
+	  $(INSTALL_DATA) ${glibcxx_srcdir}/include/bits/$${file} $(DESTDIR)${gxx_include_dir}/bits; done
+	$(mkinstalldirs) $(DESTDIR)${host_installdir}
+	for file in ${host_srcdir}/os_defines.h ${host_builddir}/c++config.h \
+	  ${glibcxx_srcdir}/$(ABI_TWEAKS_SRCDIR)/cxxabi_tweaks.h \
+	  ${glibcxx_srcdir}/$(CPU_DEFINES_SRCDIR)/cpu_defines.h; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${host_installdir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${std_builddir}
+	for file in limits type_traits atomic bit concepts version; do \
+	  $(INSTALL_DATA) ${std_builddir}/$${file} $(DESTDIR)${gxx_include_dir}/${std_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${c_base_builddir}
+	for file in ciso646 cstddef cfloat climits cstdint cstdlib \
+	  cstdalign cstdarg cstdbool; do \
+	  $(INSTALL_DATA) ${c_base_builddir}/$${file} $(DESTDIR)${gxx_include_dir}/${c_base_builddir}; done
+
+# The real deal.
+install-headers:
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${bits_builddir}
+	for file in ${bits_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${bits_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${backward_builddir}
+	for file in ${backward_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${backward_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${ext_builddir}
+	for file in ${ext_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${ext_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${pb_builddir}
+	for dir in ${pb_subdirs}; do \
+	  $(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/$${dir} ; done
+	for file in ${pb_headers1}; do \
+	  install_base=$(DESTDIR)${gxx_include_dir}/${pb_builddir} ; \
+	  relative_name=`echo $$file | sed -e "s|${pb_srcdir}|.|g"` ;\
+	  $(INSTALL_DATA) $${file} $${install_base}/$${relative_name} ; done
+	for file in ${pb_headers2}; do \
+	  install_base=$(DESTDIR)${gxx_include_dir}/${pb_builddir} ; \
+	  relative_name=`echo $$file | sed -e "s|${pb_srcdir}|.|g"` ;\
+	  $(INSTALL_DATA) $${file} $${install_base}/$${relative_name} ; done
+	for file in ${pb_headers3}; do \
+	  install_base=$(DESTDIR)${gxx_include_dir}/${pb_builddir} ; \
+	  relative_name=`echo $$file | sed -e "s|${pb_srcdir}|.|g"` ;\
+	  $(INSTALL_DATA) $${file} $${install_base}/$${relative_name} ; done
+	for file in ${pb_headers4}; do \
+	  install_base=$(DESTDIR)${gxx_include_dir}/${pb_builddir} ; \
+	  relative_name=`echo $$file | sed -e "s|${pb_srcdir}|.|g"` ;\
+	  $(INSTALL_DATA) $${file} $${install_base}/$${relative_name} ; done
+	for file in ${pb_headers5}; do \
+	  install_base=$(DESTDIR)${gxx_include_dir}/${pb_builddir} ; \
+	  relative_name=`echo $$file | sed -e "s|${pb_srcdir}|.|g"` ;\
+	  $(INSTALL_DATA) $${file} $${install_base}/$${relative_name} ; done
+	for file in ${pb_headers6}; do \
+	  install_base=$(DESTDIR)${gxx_include_dir}/${pb_builddir} ; \
+	  relative_name=`echo $$file | sed -e "s|${pb_srcdir}|.|g"` ;\
+	  $(INSTALL_DATA) $${file} $${install_base}/$${relative_name} ; done
+	for file in ${pb_headers7}; do \
+	  install_base=$(DESTDIR)${gxx_include_dir}/${pb_builddir} ; \
+	  relative_name=`echo $$file | sed -e "s|${pb_srcdir}|.|g"` ;\
+	  $(INSTALL_DATA) $${file} $${install_base}/$${relative_name} ; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${tr1_builddir}
+	for file in ${tr1_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${tr1_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${tr2_builddir}
+	for file in ${tr2_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${tr2_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${decimal_builddir}
+	for file in ${decimal_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${decimal_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${experimental_builddir}
+	for file in ${experimental_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${experimental_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${experimental_bits_builddir}
+	for file in ${experimental_bits_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${experimental_bits_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${c_base_builddir}
+	for file in ${c_base_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${c_base_builddir}; done
+	c_base_headers_extra_install='$(c_base_headers_extra)';\
+	for file in $$c_base_headers_extra_install; do \
+	  $(INSTALL_DATA) $$file $(DESTDIR)${gxx_include_dir}/${bits_builddir}; done
+	c_compatibility_headers_install='$(c_compatibility_headers_extra)';\
+	for file in $$c_compatibility_headers_install; do \
+	  $(INSTALL_DATA) $$file $(DESTDIR)${gxx_include_dir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${std_builddir}
+	for file in ${std_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${std_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${debug_builddir}
+	for file in ${debug_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${debug_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${parallel_builddir}
+	for file in ${parallel_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${parallel_builddir}; done
+	$(mkinstalldirs) $(DESTDIR)${host_installdir}
+	for file in ${host_headers} ${bits_host_headers} ${host_headers_extra} \
+	 ${thread_host_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${host_installdir}; done
+	$(mkinstalldirs) $(DESTDIR)${host_installdir}/../ext
+	for file in ${ext_host_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${host_installdir}/../ext; done
+	$(mkinstalldirs) $(DESTDIR)${gxx_include_dir}/${pstl_builddir}
+	for file in ${pstl_headers}; do \
+	  $(INSTALL_DATA) $${file} $(DESTDIR)${gxx_include_dir}/${pstl_builddir}; done
+
+# To remove directories.
+clean-local:
+	rm -rf ${pch_output_dirs}
+
+# Stop implicit '.o' make rules from ever stomping on extensionless
+# headers, in the improbable case where some foolish, crack-addled
+# developer tries to create them via make in the include build
+# directory. (This is more of an example of how this kind of rule can
+# be made.)
+.PRECIOUS: $(std_headers) $(c_base_headers) $(tr1_headers) $(tr2_headers)
+	   $(decimal_headers) $(ext_headers) $(experimental_headers)
+	   $(experimental_bits_headers)
+$(std_headers): ; @:
+$(c_base_headers): ; @:
+$(tr1_headers): ; @:
+$(decimal_headers): ; @:
+$(ext_headers): ; @:
+$(experimental_headers): ; @:
+$(experimental_bits_headers): ; @:
+
+# See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81797
+@INCLUDE_DIR_NOTPARALLEL_TRUE@.NOTPARALLEL:
+
 # Testsuite/check forwarding targets.
 check-%:
 	cd testsuite && $(MAKE) $@
diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
index 89835759069..351941801ce 100644
--- a/libstdc++-v3/include/Makefile.am
+++ b/libstdc++-v3/include/Makefile.am
@@ -69,6 +69,7 @@ std_headers = \
 	${std_srcdir}/ratio \
 	${std_srcdir}/regex \
 	${std_srcdir}/scoped_allocator \
+	${std_srcdir}/semaphore \
 	${std_srcdir}/set \
 	${std_srcdir}/shared_mutex \
 	${std_srcdir}/span \
diff --git a/libstdc++-v3/include/Makefile.in b/libstdc++-v3/include/Makefile.in
index 123d24bb1c6..7d856e4122e 100644
--- a/libstdc++-v3/include/Makefile.in
+++ b/libstdc++-v3/include/Makefile.in
@@ -414,6 +414,7 @@ std_headers = \
 	${std_srcdir}/ratio \
 	${std_srcdir}/regex \
 	${std_srcdir}/scoped_allocator \
+	${std_srcdir}/semaphore \
 	${std_srcdir}/set \
 	${std_srcdir}/shared_mutex \
 	${std_srcdir}/span \
diff --git a/libstdc++-v3/include/std/semaphore b/libstdc++-v3/include/std/semaphore
new file mode 100644
index 00000000000..70e93ea4bea
--- /dev/null
+++ b/libstdc++-v3/include/std/semaphore
@@ -0,0 +1,245 @@
+//<semaphore> -*- C++ -*-
+
+// Copyright (C) 2019-2020 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
+
+#include <bits/c++config.h>
+#if defined(_GLIBCXX_HAS_GTHREADS)
+#include <bits/gthr.h>
+#endif
+
+#ifdef _GLIBCXX_USE_NANOSLEEP
+# include <cerrno>  // errno, EINTR
+# include <time.h>  // nanosleep
+#else
+# ifdef _GLIBCXX_HAVE_SLEEP
+#  include <unistd.h>
+# elif defined(_GLIBCXX_HAVE_WIN32_SLEEP)
+#  include <windows.h>
+# else
+#  error "No sleep function known for this target"
+# endif
+#endif
+
+#include <bits/atomic_futex.h>
+
+#include <atomic>
+#include <chrono>
+
+#if __cplusplus > 201703L
+#define __cpp_lib_semaphore 201907L
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+	// TODO: replace this with a real implementation of std::binary_semaphore
+	struct binary_semaphore
+	{
+		explicit binary_semaphore(int __d) : _M_counter(__d > 0) { }
+
+		static constexpr std::ptrdiff_t
+		max() noexcept
+		{
+		 return 1;
+		}
+
+		void release() { _M_counter.fetch_add(1, memory_order::release); }
+
+		void acquire()
+		{
+		 while (!_M_try_acquire())
+			 {
+				_S_yield();
+			 }
+		}
+
+		bool
+		try_acquire() noexcept
+		{
+		 return _M_try_acquire(1u, 0u);
+		}
+
+		template<class _Rep, class _Period>
+		bool try_acquire_for(const std::chrono::duration<_Rep, _Period>& __rel_time)
+		{
+		 auto __abst = std::chrono::steady_clock::now() + __rel_time;
+		 return try_acquire_until(__abst);
+		}
+
+		template<class _Clock, class _Duration>
+		bool try_acquire_until(const std::chrono::time_point<_Clock, _Duration>& __abs_time)
+		{
+		 do
+			 {
+				if (_M_try_acquire())
+					{
+					 return true;
+					}
+				_S_yield();
+			 } while (std::chrono::steady_clock::now() < __abs_time);
+		 return false;
+		}
+
+	private:
+		static void
+		_S_relax() noexcept
+		{
+#if defined __i386__ || defined __x86_64__
+		 __builtin_ia32_pause();
+#elif defined _GLIBCXX_USE_SCHED_YIELD
+		 __gthread_yield();
+#endif
+		}
+
+    static void
+    _S_yield() noexcept
+    {
+#if defined _GLIBCXX_USE_SCHED_YIELD
+      __gthread_yield();
+#endif
+    }
+
+    static void
+    _S_sleep_for(std::chrono::microseconds __rtime)
+    {
+     if (__rtime <= __rtime.zero())
+       return;
+     auto __s = chrono::duration_cast<chrono::seconds>(__rtime);
+     auto __ns = chrono::duration_cast<chrono::nanoseconds>(__rtime - __s);
+#ifdef _GLIBCXX_USE_NANOSLEEP
+     __gthread_time_t __ts =
+     {
+	    static_cast<std::time_t>(__s.count()),
+	    static_cast<long>(__ns.count())
+     };
+
+     while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)
+       { }
+#elif defined(_GLIBCXX_HAVE_SLEEP)
+     const auto __target = chrono::steady_clock::now() + __s + __ns;
+     while (true)
+       {
+         unsigned __secs = __s.count();
+         if (__ns.count() > 0)
+           {
+# ifdef _GLIBCXX_HAVE_USLEEP
+             long __us = __ns.count() / 1000;
+             if (__us == 0)
+               __us = 1;
+             ::usleep(__us);
+# else
+             if (__ns.count() > 1000000 || __secs == 0)
+               ++__secs; // No sub-second sleep function, so round up.
+#endif
+           }
+
+         if (__secs > 0)
+           {
+             // Sleep in a loop to handle interruption by signals:
+             while ((__secs = ::sleep(__secs)))
+               { }
+           }
+         const auto __now = chrono::steady_clock::now();
+         if (__now >= __target)
+           break;
+         __s = chrono::duration_cast<chrono::seconds>(__target - __now);
+         __ns = chrono::duration_cast<chrono::nanoseconds>(__target - (__now + __s));
+       }
+#elif defined(_GLIBCXX_HAVE_WIN32_SLEEP)
+     unsigned long __ms = __ns.count() / 1000000;
+     if (__ns.count() > 0 && __ms == 0)
+       __ms = 1;
+     ::Sleep(chrono::milliseconds(__s).count() + __ms);
+#endif
+    }
+
+    struct __backoff
+    {
+      int _M_rtime_us = 64;
+
+      void
+      _M_sleep()
+      {
+        _S_sleep_for(std::chrono::microseconds(_M_rtime_us));
+        auto __next_rtime_us = _M_rtime_us + (_M_rtime_us >> 2);
+        _M_rtime_us = __next_rtime_us < 1024 ? __next_rtime_us : 1024;
+      }
+    };
+
+		bool
+    _M_try_acquire(unsigned __spin_ct1, unsigned __spin_ct2)
+		{
+		 int __old = 1;
+     for (auto __spin = 0; __spin < __spin_ct1; ++__spin)
+       {
+         if (_M_counter.compare_exchange_weak(__old, 0,
+                                              memory_order::acquire,
+                                              memory_order::relaxed))
+           return true;
+				 __old = 1;
+       }
+
+     for (auto __spin = 0; __spin < __spin_ct2; _S_relax(), ++__spin)
+			 {
+         if (_M_counter.compare_exchange_weak(__old, 0,
+                                              memory_order::acquire,
+                                              memory_order::relaxed))
+           return true;
+				 __old = 1;
+			 }
+
+     __backoff __b;
+     for (auto __spin = 0; __spin < __spin_ct2; __b._M_sleep(), ++__spin)
+			 {
+         if (_M_counter.compare_exchange_weak(__old, 0,
+                                              memory_order::acquire,
+                                              memory_order::relaxed))
+           return true;
+				 __old = 1;
+			 }
+     return false;
+		}
+
+		static constexpr unsigned _S_spin_ct1 = 16u;
+		static constexpr unsigned _S_spin_ct2 = 16u;
+
+		bool
+		_M_try_acquire()
+		{
+			return _M_try_acquire(_S_spin_ct1, _S_spin_ct2);
+		}
+
+		atomic<int> _M_counter;
+	};
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace
+#endif // _GLIBCXX_SEMAPHORE
+#endif // __cplusplus > 201703L
diff --git a/libstdc++-v3/include/std/version b/libstdc++-v3/include/std/version
index d8a97767453..6ab9d0924a7 100644
--- a/libstdc++-v3/include/std/version
+++ b/libstdc++-v3/include/std/version
@@ -188,6 +188,8 @@
 #define __cpp_lib_interpolate 201902L
 #ifdef _GLIBCXX_HAS_GTHREADS
 # define __cpp_lib_jthread 201907L
+// TODO uncomment when binary/counted_semaphore are fully implemented
+// # define __cpp_lib_semaphore 201907L
 #endif
 #define __cpp_lib_list_remove_return_type 201806L
 #define __cpp_lib_math_constants 201907L
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.
+//
+// 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/binary_semaphore.cc b/libstdc++-v3/testsuite/30_threads/semaphore/binary_semaphore.cc
new file mode 100644
index 00000000000..1a42d323ca0
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/binary_semaphore.cc
@@ -0,0 +1,47 @@
+// Copyright (C) 2019-2020 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 -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+#include <semaphore>
+#include <chrono>
+#include <thread>
+
+#include <testsuite_hooks.h>
+
+int main()
+{
+  std::binary_semaphore s(1);
+
+  auto ar = [&]() {
+              for(auto i = 0u; i < 512; ++i) {
+                s.acquire();
+                std::this_thread::sleep_for(std::chrono::microseconds(1));
+                s.release();
+              }
+            };
+
+  std::thread t(ar);
+  ar();
+
+  t.join();
+
+  return 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..295cfa9bca8
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire.cc
@@ -0,0 +1,36 @@
+// Copyright (C) 2019-2020 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 -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+#include <semaphore>
+
+int main()
+{
+  std::binary_semaphore s(1);
+
+  s.acquire();
+  if (s.try_acquire())
+    return -1;
+  s.release();
+  if (!s.try_acquire())
+    return -1;
+  return 0;
+}
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..a04b39b5401
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_for.cc
@@ -0,0 +1,72 @@
+// Copyright (C) 2019-2020 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 -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+#include <semaphore>
+#include <chrono>
+#include <thread>
+#include <mutex>
+#include <condition_variable>
+
+int main()
+{
+  using lock_type = std::unique_lock<std::mutex>;
+
+  bool ready = false;
+  lock_type::mutex_type m;
+  std::condition_variable cv;
+
+  std::binary_semaphore s(1);
+  auto ar =[&] {
+             s.acquire();
+             {
+               lock_type l(m);
+               ready = true;
+             }
+             cv.notify_one();
+             std::this_thread::sleep_for(std::chrono::milliseconds(500));
+             s.release();
+           };
+
+  std::thread t1(ar);
+  {
+    lock_type l(m, std::defer_lock);
+    cv.wait(l, [&] { return ready; });
+
+    if (s.try_acquire_for(std::chrono::milliseconds(100)))
+      return -1;
+    t1.join();
+    if (!s.try_acquire())
+      return -1;
+    s.release();
+    ready = false;
+  }
+
+  std::thread t2(ar);
+  {
+    lock_type l(m, std::defer_lock);
+    cv.wait(l, [&] { return ready; });
+    if (!s.try_acquire_for(std::chrono::milliseconds(1009)))
+      return -1;
+    t2.join();
+  }
+  return 0;
+}
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..987b655a6da
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_until.cc
@@ -0,0 +1,74 @@
+// Copyright (C) 2019-2020 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 -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+#include <semaphore>
+#include <chrono>
+#include <thread>
+#include <mutex>
+#include <condition_variable>
+
+int main()
+{
+  using lock_type = std::unique_lock<std::mutex>;
+
+  bool ready = false;
+  lock_type::mutex_type m;
+  std::condition_variable cv;
+
+  auto abst = std::chrono::steady_clock::now();
+
+  std::binary_semaphore s(1);
+  auto ar =[&] {
+             s.acquire();
+             {
+               lock_type l(m);
+               ready = true;
+             }
+             cv.notify_one();
+             std::this_thread::sleep_until(abst + std::chrono::milliseconds(500));
+             s.release();
+           };
+
+  std::thread t1(ar);
+  {
+    lock_type l(m, std::defer_lock);
+    cv.wait(l, [&] { return ready; });
+
+    if (s.try_acquire_until(abst + std::chrono::milliseconds(100)))
+      return -1;
+    t1.join();
+    if (!s.try_acquire())
+      return -1;
+    s.release();
+    ready = false;
+  }
+
+  std::thread t2(ar);
+  {
+    lock_type l(m, std::defer_lock);
+    cv.wait(l, [&] { return ready; });
+    if (!s.try_acquire_until(abst + std::chrono::milliseconds(1009)))
+      return -1;
+    t2.join();
+  }
+  return 0;
+}
-- 
2.24.1

Re: [PATCH] Add c++2a binary_semaphore

[Thomas Rodgers]

[-- Attachment #1: Type: text/plain, Size: 5960 bytes --]

Hopefully less borked than the previous one, adds futex support.

----- Original Message -----
From: "Thomas Rodgers" <trodgers@redhat.com>
To: gcc-patches@gcc.gnu.org, libstdc++@gcc.gnu.org
Sent: Wednesday, February 19, 2020 7:18:36 PM
Subject: Re: [PATCH] Add c++2a binary_semaphore

Should address the previous issues, adds backoff logic.

    * include/std/semaphore: New file.
    * include/std/version (__cpp_lib_semaphore): Add feature test macro.
    * include/Makefile.am (std_headers): add semaphore.
    * include/Makefile.in: Regenerate.
    * testsuite/30_threads/semaphore/1.cc: New test.
    * testsuite/30_threads/semaphore/2.cc: New test.
    * testsuite/30_threads/semaphore/binary_semaphore.cc: New test.
    * testsuite/30_threads/semaphore/try_acquire.cc: New test.
    * testsuite/30_threads/semaphore/try_acquire_for.cc: New test.
    * testsuite/30_threads/semaphore/try_acquire_until.cc: New test.

----- Original Message -----
From: "Jonathan Wakely" <jwakely@redhat.com>
To: "Thomas Rodgers" <trodgers@redhat.com>
Cc: gcc-patches@gcc.gnu.org, libstdc++@gcc.gnu.org
Sent: Tuesday, February 18, 2020 6:25:41 AM
Subject: Re: [PATCH] Add c++2a binary_semaphore

On 18/02/20 01:46 -0500, Thomas Rodgers wrote:
>This patch adds the c++2a semaphore header and binary_semaphore type. The implementation is not complete, this patch is just to solicit initial feedback.

Here is some initial feedback on comments and whitespace :-)

>diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
>index 89835759069..2dbb7d3a6b1 100644
>--- a/libstdc++-v3/include/Makefile.am
>+++ b/libstdc++-v3/include/Makefile.am
>@@ -69,6 +69,7 @@ std_headers = \
> 	${std_srcdir}/ratio \
> 	${std_srcdir}/regex \
> 	${std_srcdir}/scoped_allocator \
>+  ${std_srcdir}/semaphore \

Indentation is borked.

> 	${std_srcdir}/set \
> 	${std_srcdir}/shared_mutex \
> 	${std_srcdir}/span \
>diff --git a/libstdc++-v3/include/std/semaphore b/libstdc++-v3/include/std/semaphore
>new file mode 100644
>index 00000000000..e3e88a50eec
>--- /dev/null
>+++ b/libstdc++-v3/include/std/semaphore
>@@ -0,0 +1,131 @@
>+// <stop_token> -*- C++ -*-

Wrong header name in comment.

>+
>+// Copyright (C) 2019-2020 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/stop_token

Wrong name again.

>+ *  This is a Standard C++ Library header.
>+ */
>+
>+#ifndef _GLIBCXX_SEMAPHORE
>+#define _GLIBCXX_SEMAPHORE
>+
>+#if __cplusplus > 201703L
>+#define __cpp_lib_semaphore 201907L

We shouldn't define this until the file is complete, i.e. when it
provides binary_semaphore and counting_semaphore.

>+
>+#include <cstddef>

Is this header needed? ptrdiff_t and size_t are both defined in
<bits/c++config.h> which every header already includes.

>+#include <atomic>
>+#include <chrono>
>+
>+namespace std _GLIBCXX_VISIBILITY(default)
>+{
>+_GLIBCXX_BEGIN_NAMESPACE_VERSION
>+
>+  // TODO: replace this with a real implementation of std::binary_semaphore
>+  struct binary_semaphore
>+{

Indentation is borked here too.

>+  explicit binary_semaphore(int __d) : _M_counter(__d > 0) { }
>+
>+  static constexpr std::ptrdiff_t
>+  max() noexcept
>+  {
>+   return 1;
>+  }
>+
>+  void release() { _M_counter.fetch_add(1, memory_order::release); }
>+
>+  void acquire()
>+  {
>+   while (!_M_try_acquire())
>+     {
>+      _S_yield();
>+     }
>+  }
>+
>+  bool
>+  try_acquire() noexcept
>+  {
>+   return _M_try_acquire(1u);
>+  }
>+
>+  template<class _Rep, class _Period>
>+  bool try_acquire_for(const std::chrono::duration<_Rep, _Period>& __rel_time)
>+  {
>+   auto __abst = std::chrono::steady_clock::now() + __rel_time;
>+   return try_acquire_until(__abst);
>+  }
>+
>+  template<class _Clock, class _Duration>
>+  bool try_acquire_until(const std::chrono::time_point<_Clock, _Duration>& __abs_time)
>+  {
>+   do
>+     {
>+      if (_M_try_acquire())
>+        {
>+         return true;
>+        }
>+     } while (std::chrono::steady_clock::now() < __abs_time);
>+   return false;
>+  }
>+
>+private:
>+  static void
>+  _S_yield() noexcept
>+  {
>+#if defined __i386__ || defined __x86_64__
>+   __builtin_ia32_pause();
>+#elif defined _GLIBCXX_USE_SCHED_YIELD
>+   __gthread_yield();
>+#endif
>+  }
>+
>+  bool
>+  _M_try_acquire(unsigned __spin_ct)
>+  {
>+   int __old = 1;
>+   while (!_M_counter.compare_exchange_weak(__old, 0,
>+                                            memory_order::acquire,
>+                                            memory_order::relaxed))
>+     {
>+       if (--__spin_ct == 0)
>+         {
>+           return false;
>+         }
>+      __old = 1;
>+     }
>+   return true;
>+  }
>+
>+  static constexpr unsigned _S_spin_ct = 64u;
>+  bool
>+  _M_try_acquire()
>+  {
>+    return _M_try_acquire(1);
>+  }
>+
>+  atomic<int> _M_counter;
>+};
>+
>+_GLIBCXX_END_NAMESPACE_VERSION
>+} // namespace
>+#endif // __cplusplus > 201703L
>+#endif // _GLIBCXX_STOP_TOKEN

Wrong macro name in comment.


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From aabb58f9381671aab73379e10359488dbecfe992 Mon Sep 17 00:00:00 2001
From: Thomas Rodgers <rodgert@thufir.appliantology.local>
Date: Mon, 24 Feb 2020 17:17:35 -0800
Subject: [PATCH] Add c++2a binary_semaphore

    * include/std/semaphore: New file.
    * include/std/version (__cpp_lib_semaphore): Add feature test macro.
    * include/Makefile.am (std_headers): add semaphore.
    * include/Makefile.in: Regenerate.
    * testsuite/30_threads/semaphore/1.cc: New test.
    * testsuite/30_threads/semaphore/2.cc: New test.
    * testsuite/30_threads/semaphore/binary_semaphore.cc: New test.
    * testsuite/30_threads/semaphore/try_acquire.cc: New test.
    * testsuite/30_threads/semaphore/try_acquire_for.cc: New test.
    * testsuite/30_threads/semaphore/try_acquire_until.cc: New test.
---
 libstdc++-v3/include/Makefile.am              |   1 +
 libstdc++-v3/include/Makefile.in              |   1 +
 libstdc++-v3/include/std/semaphore            | 323 ++++++++++++++++++
 libstdc++-v3/include/std/version              |   2 +
 .../testsuite/30_threads/semaphore/1.cc       |  27 ++
 .../testsuite/30_threads/semaphore/2.cc       |  27 ++
 .../30_threads/semaphore/binary_semaphore.cc  |  49 +++
 .../30_threads/semaphore/try_acquire.cc       |  36 ++
 .../30_threads/semaphore/try_acquire_for.cc   |  75 ++++
 .../30_threads/semaphore/try_acquire_until.cc |  75 ++++
 10 files changed, 616 insertions(+)
 create mode 100644 libstdc++-v3/include/std/semaphore
 create mode 100644 libstdc++-v3/testsuite/30_threads/semaphore/1.cc
 create mode 100644 libstdc++-v3/testsuite/30_threads/semaphore/2.cc
 create mode 100644 libstdc++-v3/testsuite/30_threads/semaphore/binary_semaphore.cc
 create mode 100644 libstdc++-v3/testsuite/30_threads/semaphore/try_acquire.cc
 create mode 100644 libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_for.cc
 create mode 100644 libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_until.cc

diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
index 89835759069..351941801ce 100644
--- a/libstdc++-v3/include/Makefile.am
+++ b/libstdc++-v3/include/Makefile.am
@@ -69,6 +69,7 @@ std_headers = \
 	${std_srcdir}/ratio \
 	${std_srcdir}/regex \
 	${std_srcdir}/scoped_allocator \
+	${std_srcdir}/semaphore \
 	${std_srcdir}/set \
 	${std_srcdir}/shared_mutex \
 	${std_srcdir}/span \
diff --git a/libstdc++-v3/include/Makefile.in b/libstdc++-v3/include/Makefile.in
index 123d24bb1c6..7d856e4122e 100644
--- a/libstdc++-v3/include/Makefile.in
+++ b/libstdc++-v3/include/Makefile.in
@@ -414,6 +414,7 @@ std_headers = \
 	${std_srcdir}/ratio \
 	${std_srcdir}/regex \
 	${std_srcdir}/scoped_allocator \
+	${std_srcdir}/semaphore \
 	${std_srcdir}/set \
 	${std_srcdir}/shared_mutex \
 	${std_srcdir}/span \
diff --git a/libstdc++-v3/include/std/semaphore b/libstdc++-v3/include/std/semaphore
new file mode 100644
index 00000000000..18b63426bcb
--- /dev/null
+++ b/libstdc++-v3/include/std/semaphore
@@ -0,0 +1,323 @@
+//<semaphore> -*- C++ -*-
+
+// Copyright (C) 2019-2020 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
+
+#include <bits/c++config.h>
+#if defined(_GLIBCXX_HAS_GTHREADS)
+#include <bits/gthr.h>
+#endif
+
+#ifdef _GLIBCXX_USE_NANOSLEEP
+# include <cerrno>	// errno, EINTR
+# include <time.h>	// nanosleep
+#else
+# ifdef _GLIBCXX_HAVE_SLEEP
+#	 include <unistd.h>
+# elif defined(_GLIBCXX_HAVE_WIN32_SLEEP)
+#	 include <windows.h>
+# else
+#	 error "No sleep function known for this target"
+# endif
+#endif
+
+#ifdef _GLIBCXX_HAVE_LINUX_FUTEX
+#include <climits>
+#include <unistd.h>
+#include <syscall.h>
+#include <sys/time.h>
+#endif
+
+#include <atomic>
+#include <chrono>
+
+#include <iostream>
+#if __cplusplus > 201703L
+#define __cpp_lib_semaphore 201907L
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+ _GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+  struct binary_semaphore
+  {
+    explicit binary_semaphore(int __d) : _M_counter(__d > 0) { }
+
+    static constexpr std::ptrdiff_t
+    max() noexcept { return 1; }
+
+    void
+    release()
+    {
+       _M_counter.fetch_add(1, memory_order::release);
+#ifdef _GLIBCXX_HAVE_LINUX_FUTEX
+       _S_futex_notify_all((int*)(void*)&_M_counter);
+#endif
+    }
+
+    void
+    acquire()
+    {
+      while (!_M_try_acquire())
+	{
+	  if (_M_try_acquire_sleep())
+	    break;
+	}
+    }
+
+    bool
+    try_acquire() noexcept
+    {
+       return _M_try_acquire_spin(1u, 0u);
+    }
+
+    template<class _Rep, class _Period>
+      bool
+      try_acquire_for(const std::chrono::duration<_Rep, _Period>& __rel_time)
+      { return try_acquire_until(__clock_t::now()  + __rel_time); }
+
+    template<class _Clock, class _Duration>
+      bool
+      try_acquire_until(const std::chrono::time_point<_Clock, _Duration>& __abs_time)
+      {
+	const auto __c_entry = _Clock::now();
+	const auto __s_entry = __clock_t::now();
+	const auto __delta = __abs_time -__c_entry;
+	const auto __s_atime = __s_entry + __delta;
+	bool __ret = _M_try_acquire();
+	while (!!__ret && __s_atime < __clock_t::now());
+	  {
+#ifdef _GLIBCXX_HAVE_LINUX_FUTEX
+	    const auto __s = std::chrono::time_point_cast<std::chrono::seconds>(__s_atime);
+	    const auto __ns = std::chrono::duration_cast<std::chrono::nanoseconds>(__s_atime - __s);
+	    if (_S_futex_wait_until((int*)(void*)&_M_counter, 0,
+				    true, __s.time_since_epoch(), __ns))
+	      __ret = _M_try_acquire();
+#else
+	    __ret = _M_try_acquire_sleep()
+#endif
+	  };
+	return __ret;
+      }
+
+  private:
+    static void
+    _S_relax() noexcept
+    {
+#if defined __i386__ || defined __x86_64__
+      __builtin_ia32_pause();
+#elif defined _GLIBCXX_USE_SCHED_YIELD
+      __gthread_yield();
+#endif
+    }
+
+    static void
+    _S_yield() noexcept
+    {
+#if defined _GLIBCXX_USE_SCHED_YIELD
+      __gthread_yield();
+#endif
+    }
+
+    static void
+    _S_sleep_for(std::chrono::microseconds __rtime)
+    {
+      if (__rtime <= __rtime.zero())
+	return;
+      auto __s = chrono::duration_cast<chrono::seconds>(__rtime);
+      auto __ns = chrono::duration_cast<chrono::nanoseconds>(__rtime - __s);
+#ifdef _GLIBCXX_USE_NANOSLEEP
+      __gthread_time_t __ts =
+      {
+	static_cast<std::time_t>(__s.count()),
+	static_cast<long>(__ns.count())
+      };
+
+      while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)
+	{ }
+#elif defined(_GLIBCXX_HAVE_SLEEP)
+      const auto __target = chrono::steady_clock::now() + __s + __ns;
+      while (true)
+	{
+	  unsigned __secs = __s.count();
+	  if (__ns.count() > 0)
+	    {
+# ifdef _GLIBCXX_HAVE_USLEEP
+	      long __us = __ns.count() / 1000;
+	      if (__us == 0)
+		__us = 1;
+	      ::usleep(__us);
+# else
+	      if (__ns.count() > 1000000 || __secs == 0)
+		++__secs; // No sub-second sleep function, so round up.
+#endif
+	    }
+
+	  if (__secs > 0)
+	    {
+	      // Sleep in a loop to handle interruption by signals:
+	      while ((__secs = ::sleep(__secs)))
+		{ }
+	    }
+	  const auto __now = chrono::steady_clock::now();
+	  if (__now >= __target)
+	    break;
+	  __s = chrono::duration_cast<chrono::seconds>(__target - __now);
+	  __ns = chrono::duration_cast<chrono::nanoseconds>(__target - (__now + __s));
+	}
+#elif defined(_GLIBCXX_HAVE_WIN32_SLEEP)
+	unsigned long __ms = __ns.count() / 1000000;
+	if (__ns.count() > 0 && __ms == 0)
+	  __ms = 1;
+	::Sleep(chrono::milliseconds(__s).count() + __ms);
+#endif
+	}
+
+
+    bool
+    _M_try_acquire_spin(unsigned __spin_ct1, unsigned __spin_ct2)
+    {
+      int __old = 1;
+      for (auto __spin = 0; __spin < __spin_ct1; ++__spin)
+	{
+	  if (_M_counter.compare_exchange_weak(__old, 0,
+					       memory_order::acquire,
+					       memory_order::relaxed))
+	    return true;
+	  __old = 1;
+	}
+
+	for (auto __spin = 0; __spin < __spin_ct2; _S_relax(), ++__spin)
+	  {
+	    if (_M_counter.compare_exchange_weak(__old, 0,
+						 memory_order::acquire,
+						 memory_order::relaxed))
+	      return true;
+	    __old = 1;
+	  }
+      return false;
+    }
+
+#ifndef _GLIBCXX_HAVE_LINUX_FUTEX
+    struct __backoff
+    {
+      int _M_rtime_us = 64;
+
+      void
+      _M_sleep()
+      {
+	_S_sleep_for(std::chrono::microseconds(_M_rtime_us));
+	auto __next_rtime_us = _M_rtime_us + (_M_rtime_us >> 2);
+	_M_rtime_us = __next_rtime_us < 1024 ? __next_rtime_us : 1024;
+      }
+    };
+#endif
+
+    bool
+    _M_try_acquire_sleep()
+    {
+      int __old = 1;
+#ifdef _GLIBCXX_HAVE_LINUX_FUTEX
+      _S_futex_wait_until((int*)(void*)&_M_counter,__old);
+#else
+      __backoff __b;
+      for (auto __spin = 0; ; __b._M_sleep(), ++__spin)
+	{
+	  if (_M_counter.compare_exchange_weak(__old, 0,
+					       memory_order::acquire,
+					       memory_order::relaxed))
+	    return true;
+	  __old = 1;
+	}
+#endif
+      return false;
+    }
+
+    using __clock_t = std::chrono::system_clock;
+    static constexpr unsigned _S_spin_ct1 = 16u;
+    static constexpr unsigned _S_spin_ct2 = 16u;
+
+    bool
+    _M_try_acquire()
+    {
+      return _M_try_acquire_spin(_S_spin_ct1, _S_spin_ct2);
+    }
+
+    atomic<int> _M_counter;
+
+    static const auto _S_futex_wake_op = 1u;
+
+#ifdef _GLIBCXX_HAVE_LINUX_FUTEX
+    bool
+    _S_futex_wait_until(int* __addr, int __val,
+			bool __has_timeout = false,
+			std::chrono::seconds __s = std::chrono::seconds::zero(),
+			std::chrono::nanoseconds __ns = std::chrono::nanoseconds::zero())
+    {
+      if (!__has_timeout)
+	{
+	  syscall (SYS_futex, __addr, 0, __val, nullptr);
+	  // Can't do anything about an error here except abort, so ignore it.
+	}
+      else
+	{
+	  struct timeval __tv;
+	  gettimeofday(&__tv, NULL);
+	  struct timespec __rt;
+	  __rt.tv_sec = __s.count() - __tv.tv_sec;
+	  __rt.tv_nsec = __ns.count() - __tv.tv_usec * 1000;
+	  if (__rt.tv_nsec < 0)
+	    {
+	      __rt.tv_nsec += 1000000000;
+	      --__rt.tv_sec;
+	    }
+	  if (__rt.tv_sec < 0)
+	    return false;
+
+	  if (syscall (SYS_futex, __addr, 0, __val, &__rt) == -1)
+	    {
+	      if (errno == ETIMEDOUT)
+		return false;
+	    }
+	}
+      return true;
+    }
+
+    void
+    _S_futex_notify_all(int* __addr)
+    {
+      syscall (SYS_futex, __addr, 1, INT_MAX);
+    }
+#endif // _GLIBCXX_HAVE_LINUX_FUTEX
+  };
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace
+#endif // _GLIBCXX_SEMAPHORE
+#endif // __cplusplus > 201703L
diff --git a/libstdc++-v3/include/std/version b/libstdc++-v3/include/std/version
index d8a97767453..6ab9d0924a7 100644
--- a/libstdc++-v3/include/std/version
+++ b/libstdc++-v3/include/std/version
@@ -188,6 +188,8 @@
 #define __cpp_lib_interpolate 201902L
 #ifdef _GLIBCXX_HAS_GTHREADS
 # define __cpp_lib_jthread 201907L
+// TODO uncomment when binary/counted_semaphore are fully implemented
+// # define __cpp_lib_semaphore 201907L
 #endif
 #define __cpp_lib_list_remove_return_type 201806L
 #define __cpp_lib_math_constants 201907L
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.
+//
+// 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/binary_semaphore.cc b/libstdc++-v3/testsuite/30_threads/semaphore/binary_semaphore.cc
new file mode 100644
index 00000000000..661f0b0e32d
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/binary_semaphore.cc
@@ -0,0 +1,49 @@
+// Copyright (C) 2019-2020 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 -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+#include <semaphore>
+#include <chrono>
+#include <thread>
+
+#include <testsuite_hooks.h>
+
+int main()
+{
+  std::binary_semaphore s(1);
+
+  auto ar = [&]()
+	    {
+	      for(auto i = 0u; i < 512; ++i)
+		{
+		  s.acquire();
+		  std::this_thread::sleep_for(std::chrono::microseconds(1));
+		  s.release();
+		}
+	    };
+
+  std::thread t(ar);
+  ar();
+
+  t.join();
+
+  return 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..295cfa9bca8
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire.cc
@@ -0,0 +1,36 @@
+// Copyright (C) 2019-2020 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 -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+#include <semaphore>
+
+int main()
+{
+  std::binary_semaphore s(1);
+
+  s.acquire();
+  if (s.try_acquire())
+    return -1;
+  s.release();
+  if (!s.try_acquire())
+    return -1;
+  return 0;
+}
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..9e945094db8
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_for.cc
@@ -0,0 +1,75 @@
+// Copyright (C) 2019-2020 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 -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+#include <semaphore>
+#include <chrono>
+#include <thread>
+#include <mutex>
+#include <condition_variable>
+
+#include <iostream>
+
+int main()
+{
+  using lock_type = std::unique_lock<std::mutex>;
+
+  bool ready = false;
+  lock_type::mutex_type m;
+  std::condition_variable cv;
+
+  std::binary_semaphore s(1);
+  auto ar =[&]
+	   {
+	     s.acquire();
+	     {
+		lock_type l(m);
+		ready = true;
+	     }
+	     cv.notify_one();
+	     std::this_thread::sleep_for(std::chrono::milliseconds(500));
+	     s.release();
+	   };
+
+  std::thread t1(ar);
+  {
+    lock_type l(m, std::defer_lock);
+    cv.wait(l, [&] { return ready; });
+
+    if (s.try_acquire_for(std::chrono::milliseconds(100)))
+      return -1;
+    t1.join();
+    if (!s.try_acquire())
+      return -1;
+    s.release();
+    ready = false;
+  }
+
+  std::thread t2(ar);
+  {
+    lock_type l(m, std::defer_lock);
+    cv.wait(l, [&] { return ready; });
+    if (!s.try_acquire_for(std::chrono::milliseconds(1009)))
+      return -1;
+    t2.join();
+  }
+  return 0;
+}
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..46365ed69a2
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/try_acquire_until.cc
@@ -0,0 +1,75 @@
+// Copyright (C) 2019-2020 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 -pthread" }
+// { dg-do run { target c++2a } }
+// { dg-require-effective-target pthread }
+// { dg-require-gthreads "" }
+
+#include <semaphore>
+#include <chrono>
+#include <thread>
+#include <mutex>
+#include <condition_variable>
+
+int main()
+{
+  using lock_type = std::unique_lock<std::mutex>;
+
+  bool ready = false;
+  lock_type::mutex_type m;
+  std::condition_variable cv;
+
+  auto abst = std::chrono::steady_clock::now();
+
+  std::binary_semaphore s(1);
+  auto ar =[&]
+	   {
+	     s.acquire();
+	     {
+		lock_type l(m);
+		ready = true;
+	     }
+	     cv.notify_one();
+	     std::this_thread::sleep_until(abst + std::chrono::milliseconds(500));
+	     s.release();
+	   };
+
+  std::thread t1(ar);
+  {
+    lock_type l(m, std::defer_lock);
+    cv.wait(l, [&] { return ready; });
+
+    if (s.try_acquire_until(abst + std::chrono::milliseconds(100)))
+      return -1;
+    t1.join();
+    if (!s.try_acquire())
+      return -1;
+    s.release();
+    ready = false;
+  }
+
+  std::thread t2(ar);
+  {
+    lock_type l(m, std::defer_lock);
+    cv.wait(l, [&] { return ready; });
+    if (!s.try_acquire_until(abst + std::chrono::milliseconds(1009)))
+      return -1;
+    t2.join();
+  }
+  return 0;
+}
-- 
2.24.1

Re: [PATCH] Add c++2a binary_semaphore

[Sebastian Huber]

Hello Thomas,

some operating systems provide already an implementation of binary 
semaphores with a compatible API, e.g. RTEMS. It would be nice if I 
could use it in libstdc++. I guess you don't want to have #ifdef 
__rtems__ stuff in this code. What about defining a binary semaphore API 
for gthr.h and then implement the optional futex support in 
libgcc/gthr-posix.h?

-- 
Sebastian Huber, embedded brains GmbH

Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone   : +49 89 189 47 41-16
Fax     : +49 89 189 47 41-09
E-Mail  : sebastian.huber@embedded-brains.de
PGP     : Public key available on request.

Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.

Re: [PATCH] Add c++2a binary_semaphore

[Jonathan Wakely]

On 25/02/20 09:52 +0100, Sebastian Huber wrote:
>Hello Thomas,
>
>some operating systems provide already an implementation of binary 
>semaphores with a compatible API, e.g. RTEMS. It would be nice if I 
>could use it in libstdc++. I guess you don't want to have #ifdef 
>__rtems__ stuff in this code. What about defining a binary semaphore 
>API for gthr.h and then implement the optional futex support in 
>libgcc/gthr-posix.h?

gthr.h is supposed to be an abstraction of pthreads, not futexes. I
also don't see why more libstdc++ code should live in libgcc than
necessary.

It would be OK to add semaphore support to gthr-*.h and then have
libstdc++ either use futexes (where available) or the gthr code.

Re: [PATCH] Add c++2a binary_semaphore

[Jonathan Wakely]

On 25/02/20 12:33 +0000, Jonathan Wakely wrote:
>On 25/02/20 09:52 +0100, Sebastian Huber wrote:
>>Hello Thomas,
>>
>>some operating systems provide already an implementation of binary 
>>semaphores with a compatible API, e.g. RTEMS. It would be nice if I 
>>could use it in libstdc++. I guess you don't want to have #ifdef 
>>__rtems__ stuff in this code. What about defining a binary semaphore 
>>API for gthr.h and then implement the optional futex support in 
>>libgcc/gthr-posix.h?
>
>gthr.h is supposed to be an abstraction of pthreads, not futexes. I
>also don't see why more libstdc++ code should live in libgcc than
>necessary.
>
>It would be OK to add semaphore support to gthr-*.h and then have
>libstdc++ either use futexes (where available) or the gthr code.

Note however, that any additions to gthr.h are out of scope for GCC
10, as we're already in stage 4.

Local additions to libstdc++ for experimental C++20 features are still
OK now.

Re: [PATCH] Add c++2a binary_semaphore

[Jonathan Wakely]

On 24/02/20 21:53 -0500, Thomas Rodgers wrote:
>+    bool
>+    _S_futex_wait_until(int* __addr, int __val,
>+			bool __has_timeout = false,
>+			std::chrono::seconds __s = std::chrono::seconds::zero(),
>+			std::chrono::nanoseconds __ns = std::chrono::nanoseconds::zero())
>+    {
>+      if (!__has_timeout)
>+	{
>+	  syscall (SYS_futex, __addr, 0, __val, nullptr);
>+	  // Can't do anything about an error here except abort, so ignore it.
>+	}
>+      else
>+	{
>+	  struct timeval __tv;
>+	  gettimeofday(&__tv, NULL);
>+	  struct timespec __rt;
>+	  __rt.tv_sec = __s.count() - __tv.tv_sec;
>+	  __rt.tv_nsec = __ns.count() - __tv.tv_usec * 1000;
>+	  if (__rt.tv_nsec < 0)
>+	    {
>+	      __rt.tv_nsec += 1000000000;
>+	      --__rt.tv_sec;
>+	    }
>+	  if (__rt.tv_sec < 0)
>+	    return false;
>+
>+	  if (syscall (SYS_futex, __addr, 0, __val, &__rt) == -1)

This syscall has the same problem as https://gcc.gnu.org/PR93421 so we
should avoid introducing a new instance of the bug.