fix libstdc++/57641

diff --git a/libstdc++-v3/include/std/mutex b/libstdc++-v3/include/std/mutex
index cdd05a3..40b2e31 100644
--- a/libstdc++-v3/include/std/mutex
+++ b/libstdc++-v3/include/std/mutex
@@ -199,15 +199,57 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
   };
 
 #if _GTHREAD_USE_MUTEX_TIMEDLOCK
-  /// timed_mutex
-  class timed_mutex : private __mutex_base
-  {
+  template<typename _Derived>
+    class __timed_mutex_impl
+    {
+    protected:
 #ifdef _GLIBCXX_USE_CLOCK_MONOTONIC
-    typedef chrono::steady_clock 	  	__clock_t;
+      typedef chrono::steady_clock 	  	__clock_t;
 #else
-    typedef chrono::high_resolution_clock 	__clock_t;
+      typedef chrono::high_resolution_clock 	__clock_t;
 #endif
 
+      template<typename _Rep, typename _Period>
+	bool
+	_M_try_lock_for(const chrono::duration<_Rep, _Period>& __rtime)
+	{
+	  auto __rt = chrono::duration_cast<__clock_t::duration>(__rtime);
+	  if (ratio_greater<__clock_t::period, _Period>())
+	    ++__rt;
+
+	  return _M_try_lock_until(__clock_t::now() + __rt);
+	}
+
+      template<typename _Duration>
+	bool
+	_M_try_lock_until(const chrono::time_point<__clock_t,
+						   _Duration>& __atime)
+	{
+	  chrono::time_point<__clock_t, chrono::seconds> __s =
+	    chrono::time_point_cast<chrono::seconds>(__atime);
+
+	  chrono::nanoseconds __ns =
+	    chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
+
+	  __gthread_time_t __ts = {
+	    static_cast<std::time_t>(__s.time_since_epoch().count()),
+	    static_cast<long>(__ns.count())
+	  };
+
+	  auto __mutex = static_cast<_Derived*>(this)->native_handle();
+	  return !__gthread_mutex_timedlock(__mutex, &__ts);
+	}
+
+      template<typename _Clock, typename _Duration>
+	bool
+	_M_try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
+	{ return _M_try_lock_for(__atime - _Clock::now()); }
+    };
+
+  /// timed_mutex
+  class timed_mutex
+  : private __mutex_base, public __timed_mutex_impl<timed_mutex>
+  {
   public:
     typedef __native_type* 		  	native_handle_type;
 
@@ -237,25 +279,12 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
     template <class _Rep, class _Period>
       bool
       try_lock_for(const chrono::duration<_Rep, _Period>& __rtime)
-      { return __try_lock_for_impl(__rtime); }
+      { return _M_try_lock_for(__rtime); }
 
     template <class _Clock, class _Duration>
       bool
       try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
-      {
-	chrono::time_point<_Clock, chrono::seconds> __s =
-	  chrono::time_point_cast<chrono::seconds>(__atime);
-
-	chrono::nanoseconds __ns =
-	  chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
-
-	__gthread_time_t __ts = {
-	  static_cast<std::time_t>(__s.time_since_epoch().count()),
-	  static_cast<long>(__ns.count())
-	};
-
-	return !__gthread_mutex_timedlock(&_M_mutex, &__ts);
-      }
+      { return _M_try_lock_until(__atime); }
 
     void
     unlock()
@@ -267,40 +296,13 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
     native_handle_type
     native_handle()
     { return &_M_mutex; }
-
-  private:
-    template<typename _Rep, typename _Period>
-      typename enable_if<
-	ratio_less_equal<__clock_t::period, _Period>::value, bool>::type
-      __try_lock_for_impl(const chrono::duration<_Rep, _Period>& __rtime)
-      {
-	__clock_t::time_point __atime = __clock_t::now()
-	  + chrono::duration_cast<__clock_t::duration>(__rtime);
-
-	return try_lock_until(__atime);
-      }
-
-    template <typename _Rep, typename _Period>
-      typename enable_if<
-	!ratio_less_equal<__clock_t::period, _Period>::value, bool>::type
-      __try_lock_for_impl(const chrono::duration<_Rep, _Period>& __rtime)
-      {
-	__clock_t::time_point __atime = __clock_t::now()
-	  + ++chrono::duration_cast<__clock_t::duration>(__rtime);
-
-	return try_lock_until(__atime);
-      }
   };
 
   /// recursive_timed_mutex
-  class recursive_timed_mutex : private __recursive_mutex_base
+  class recursive_timed_mutex
+  : private __recursive_mutex_base,
+    public __timed_mutex_impl<recursive_timed_mutex>
   {
-#ifdef _GLIBCXX_USE_CLOCK_MONOTONIC
-    typedef chrono::steady_clock 		__clock_t;
-#else
-    typedef chrono::high_resolution_clock 	__clock_t;
-#endif
-
   public:
     typedef __native_type* 			native_handle_type;
 
@@ -330,25 +332,12 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
     template <class _Rep, class _Period>
       bool
       try_lock_for(const chrono::duration<_Rep, _Period>& __rtime)
-      { return __try_lock_for_impl(__rtime); }
+      { return _M_try_lock_for(__rtime); }
 
     template <class _Clock, class _Duration>
       bool
       try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
-      {
-	chrono::time_point<_Clock, chrono::seconds>  __s =
-	  chrono::time_point_cast<chrono::seconds>(__atime);
-
-	chrono::nanoseconds __ns =
-	  chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
-
-	__gthread_time_t __ts = {
-	  static_cast<std::time_t>(__s.time_since_epoch().count()),
-	  static_cast<long>(__ns.count())
-	};
-
-	return !__gthread_recursive_mutex_timedlock(&_M_mutex, &__ts);
-      }
+      { return _M_try_lock_until(__atime); }
 
     void
     unlock()
@@ -360,29 +349,6 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
     native_handle_type
     native_handle()
     { return &_M_mutex; }
-
-  private:
-    template<typename _Rep, typename _Period>
-      typename enable_if<
-	ratio_less_equal<__clock_t::period, _Period>::value, bool>::type
-      __try_lock_for_impl(const chrono::duration<_Rep, _Period>& __rtime)
-      {
-	__clock_t::time_point __atime = __clock_t::now()
-	  + chrono::duration_cast<__clock_t::duration>(__rtime);
-
-	return try_lock_until(__atime);
-      }
-
-    template <typename _Rep, typename _Period>
-      typename enable_if<
-	!ratio_less_equal<__clock_t::period, _Period>::value, bool>::type
-      __try_lock_for_impl(const chrono::duration<_Rep, _Period>& __rtime)
-      {
-	__clock_t::time_point __atime = __clock_t::now()
-	  + ++chrono::duration_cast<__clock_t::duration>(__rtime);
-
-	return try_lock_until(__atime);
-      }
   };
 #endif
 #endif // _GLIBCXX_HAS_GTHREADS
diff --git a/libstdc++-v3/include/std/shared_mutex b/libstdc++-v3/include/std/shared_mutex
index 39ab83a..ff58825 100644
--- a/libstdc++-v3/include/std/shared_mutex
+++ b/libstdc++-v3/include/std/shared_mutex
@@ -56,55 +56,17 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
   class shared_mutex
   {
 #if _GTHREAD_USE_MUTEX_TIMEDLOCK
-    struct _Mutex : mutex
+    struct _Mutex : mutex, __timed_mutex_impl<_Mutex>
     {
-      typedef chrono::steady_clock 	  	__clock_t;
-
-      template <class _Rep, class _Period>
+      template<typename _Rep, typename _Period>
 	bool
 	try_lock_for(const chrono::duration<_Rep, _Period>& __rtime)
-	{ return __try_lock_for_impl(__rtime); }
+	{ return _M_try_lock_for(__rtime); }
 
-      template <class _Clock, class _Duration>
+      template<typename _Clock, typename _Duration>
 	bool
 	try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
-	{
-	  chrono::time_point<_Clock, chrono::seconds> __s =
-	    chrono::time_point_cast<chrono::seconds>(__atime);
-
-	  chrono::nanoseconds __ns =
-	    chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
-
-	  __gthread_time_t __ts = {
-	    static_cast<std::time_t>(__s.time_since_epoch().count()),
-	    static_cast<long>(__ns.count())
-	  };
-
-	  return !__gthread_mutex_timedlock(native_handle(), &__ts);
-	}
-
-    private:
-      template<typename _Rep, typename _Period>
-	typename enable_if<
-	  ratio_less_equal<__clock_t::period, _Period>::value, bool>::type
-	__try_lock_for_impl(const chrono::duration<_Rep, _Period>& __rtime)
-	{
-	  __clock_t::time_point __atime = __clock_t::now()
-	    + chrono::duration_cast<__clock_t::duration>(__rtime);
-
-	  return try_lock_until(__atime);
-	}
-
-      template <typename _Rep, typename _Period>
-	typename enable_if<
-	  !ratio_less_equal<__clock_t::period, _Period>::value, bool>::type
-	__try_lock_for_impl(const chrono::duration<_Rep, _Period>& __rtime)
-	{
-	  __clock_t::time_point __atime = __clock_t::now()
-	    + ++chrono::duration_cast<__clock_t::duration>(__rtime);
-
-	  return try_lock_until(__atime);
-	}
+	{ return _M_try_lock_until(__atime); }
     };
 #else
     typedef mutex _Mutex;
diff --git a/libstdc++-v3/testsuite/30_threads/timed_mutex/try_lock_until/57641.cc b/libstdc++-v3/testsuite/30_threads/timed_mutex/try_lock_until/57641.cc
new file mode 100644
index 0000000..94fe5b3
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/timed_mutex/try_lock_until/57641.cc
@@ -0,0 +1,69 @@ 
+// { dg-do run { target *-*-freebsd* *-*-netbsd* *-*-linux* *-*-gnu* *-*-solaris* *-*-cygwin *-*-darwin* powerpc-ibm-aix* } }
+// { dg-options " -std=gnu++0x -pthread" { target *-*-freebsd* *-*-netbsd* *-*-linux* *-*-gnu* powerpc-ibm-aix* } }
+// { dg-options " -std=gnu++0x -pthreads" { target *-*-solaris* } }
+// { dg-options " -std=gnu++0x " { target *-*-cygwin *-*-darwin* } }
+// { dg-require-cstdint "" }
+// { dg-require-gthreads-timed "" }
+
+// Copyright (C) 2013 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <mutex>
+#include <chrono>
+#include <thread>
+#include <testsuite_hooks.h>
+
+// PR libstdc++/57641
+
+namespace C = std::chrono;
+
+// custom clock with epoch 10s before system_clock's
+struct clock
+{
+  typedef C::system_clock::rep rep;
+  typedef C::system_clock::period period;
+  typedef C::system_clock::duration duration;
+  typedef C::time_point<clock> time_point;
+  static constexpr bool is_steady = C::system_clock::is_steady;
+
+  static time_point
+  now()
+  {
+    auto sys_time = C::system_clock::now().time_since_epoch();
+    return time_point(sys_time + C::seconds(10));
+  }
+};
+
+std::timed_mutex mx;
+bool test = false;
+
+void f()
+{
+  test = mx.try_lock_until(clock::now() + C::milliseconds(1));
+}
+
+int main()
+{
+  bool test = false;
+  std::lock_guard<std::timed_mutex> l(mx);
+  auto start = C::system_clock::now();
+  std::thread t(f);
+  t.join();
+  auto stop = C::system_clock::now();
+  VERIFY( (stop - start) < C::seconds(9) );
+  VERIFY( !test );
+}