libstdc++: Add support for C++20 barriers

Adds <barrier>

libstdc++-v3/ChangeLog:

	* doc/doxygen/user.cfg.in: Add new header.
	* include/Makefile.am (std_headers): likewise.
	* include/Makefile.in: Regenerate.
	* include/precompiled/stdc++.h: Add new header.
	* include/std/barrier: New file.
	* include/std/version: Add __cpp_lib_barrier feature test macro.
	* testsuite/30_threads/barrier/1.cc: New test.
	* testsuite/30_threads/barrier/2.cc: Likewise.
	* testsuite/30_threads/barrier/arrive_and_drop.cc: Likewise.
	* testsuite/30_threads/barrier/arrive_and_wait.cc: Likewise.
	* testsuite/30_threads/barrier/arrive.cc: Likewise.
	* testsuite/30_threads/barrier/completion.cc: Likewise.

6 files changed, 251 insertions, 0 deletions

diff --git a/libstdc++-v3/testsuite/30_threads/barrier/1.cc b/libstdc++-v3/testsuite/30_threads/barrier/1.cc
new file mode 100644
index 00000000000..4c15deb1398
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/barrier/1.cc
@@ -0,0 +1,30 @@
+// 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 } }
+// { dg-require-effective-target gthreads }
+
+#include <barrier>
+
+#ifndef __cpp_lib_barrier
+# error "Feature-test macro for barrier missing in <barrier>"
+#elif __cpp_lib_barrier != 201907L
+# error "Feature-test macro for barrier has wrong value in <barrier>"
+#endif
+
+static_assert(std::barrier<>::max() > 0);
diff --git a/libstdc++-v3/testsuite/30_threads/barrier/2.cc b/libstdc++-v3/testsuite/30_threads/barrier/2.cc
new file mode 100644
index 00000000000..0fac1ef3f3c
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/barrier/2.cc
@@ -0,0 +1,28 @@
+// 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 } }
+// { dg-require-effective-target gthreads }
+
+#include <version>
+
+#ifndef __cpp_lib_barrier
+# error "Feature-test macro for barrier missing in <version>"
+#elif __cpp_lib_barrier != 201907L
+# error "Feature-test macro for barrier has wrong value in <version>"
+#endif
diff --git a/libstdc++-v3/testsuite/30_threads/barrier/arrive.cc b/libstdc++-v3/testsuite/30_threads/barrier/arrive.cc
new file mode 100644
index 00000000000..6e64e378cb0
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/barrier/arrive.cc
@@ -0,0 +1,48 @@
+// { dg-options "-std=gnu++2a" }
+// { dg-do run { target c++2a } }
+// { dg-require-gthreads "" }
+// { dg-additional-options "-pthread" { target pthread } }
+
+// 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/>.
+
+// This test is based on libcxx/test/std/thread/thread.barrier/arrive.pass.cpp
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <barrier>
+#include <thread>
+
+int main(int, char**)
+{
+  std::barrier<> b(2);
+
+  auto tok = b.arrive();
+  std::thread t([&](){
+    (void)b.arrive();
+  });
+  b.wait(std::move(tok));
+  t.join();
+
+  auto tok2 = b.arrive(2);
+  b.wait(std::move(tok2));
+}
diff --git a/libstdc++-v3/testsuite/30_threads/barrier/arrive_and_drop.cc b/libstdc++-v3/testsuite/30_threads/barrier/arrive_and_drop.cc
new file mode 100644
index 00000000000..55f40e17062
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/barrier/arrive_and_drop.cc
@@ -0,0 +1,46 @@
+// { dg-options "-std=gnu++2a" }
+// { dg-do run { target c++2a } }
+// { dg-require-gthreads "" }
+// { dg-additional-options "-pthread" { target pthread } }
+
+// 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/>.
+
+// This test is based on libcxx/test/std/thread/thread.barrier/arrive_and_drop.pass.cpp
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <barrier>
+#include <thread>
+
+int main(int, char**)
+{
+  std::barrier<> b(2);
+
+  std::thread t([&](){
+    b.arrive_and_drop();
+  });
+
+  b.arrive_and_wait();
+  b.arrive_and_wait();
+  t.join();
+}
diff --git a/libstdc++-v3/testsuite/30_threads/barrier/arrive_and_wait.cc b/libstdc++-v3/testsuite/30_threads/barrier/arrive_and_wait.cc
new file mode 100644
index 00000000000..2a3a69ae3c0
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/barrier/arrive_and_wait.cc
@@ -0,0 +1,46 @@
+// { dg-options "-std=gnu++2a" }
+// { dg-do run { target c++2a } }
+// { dg-require-gthreads "" }
+// { dg-additional-options "-pthread" { target pthread } }
+
+// 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/>.
+
+// This test is based on libcxx/test/std/thread/thread.barrier/arrive_and_wait.pass.cpp
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <barrier>
+#include <thread>
+
+int main(int, char**)
+{
+  std::barrier<> b(2);
+
+  std::thread t([&](){
+    for(int i = 0; i < 10; ++i)
+      b.arrive_and_wait();
+  });
+  for(int i = 0; i < 10; ++i)
+    b.arrive_and_wait();
+  t.join();
+}
diff --git a/libstdc++-v3/testsuite/30_threads/barrier/completion.cc b/libstdc++-v3/testsuite/30_threads/barrier/completion.cc
new file mode 100644
index 00000000000..ef6d2c3eac6
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/barrier/completion.cc
@@ -0,0 +1,53 @@
+// { dg-options "-std=gnu++2a" }
+// { dg-do run { target c++2a } }
+// { dg-require-gthreads "" }
+// { dg-additional-options "-pthread" { target pthread } }
+
+// 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/>.
+
+// This test is based on libcxx/test/std/thread/thread.barrier/completion.pass.cpp
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <barrier>
+#include <thread>
+
+#include <testsuite_hooks.h>
+
+int main(int, char**)
+{
+  int x = 0;
+  auto comp = [&] { x += 1; };
+  std::barrier<decltype(comp)> b(2, comp);
+
+  std::thread t([&](){
+      for(int i = 0; i < 10; ++i)
+	b.arrive_and_wait();
+  });
+
+  for(int i = 0; i < 10; ++i)
+    b.arrive_and_wait();
+
+  VERIFY( x == 10 );
+  t.join();
+}