--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/ada/libgnat/s-tasloc.ads	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,98 @@
+------------------------------------------------------------------------------
+--                                                                          --
+--                         GNAT RUN-TIME COMPONENTS                         --
+--                                                                          --
+--                     S Y S T E M . T A S K _ L O C K                      --
+--                                                                          --
+--                                 S p e c                                  --
+--                                                                          --
+--                     Copyright (C) 1998-2017, AdaCore                     --
+--                                                                          --
+-- GNAT is free software;  you can  redistribute it  and/or modify it under --
+-- terms of the  GNU General Public License as published  by the Free Soft- --
+-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
+-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
+-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
+-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
+--                                                                          --
+-- As a special exception 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/>.                                          --
+--                                                                          --
+-- GNAT was originally developed  by the GNAT team at  New York University. --
+-- Extensive contributions were provided by Ada Core Technologies Inc.      --
+--                                                                          --
+------------------------------------------------------------------------------
+
+--  Simple task lock and unlock routines
+
+--  A small package containing a task lock and unlock routines for creating
+--  a critical region. The lock involved is a global lock, shared by all
+--  tasks, and by all calls to these routines, so these routines should be
+--  used with care to avoid unnecessary reduction of concurrency.
+
+--  These routines may be used in a non-tasking program, and in that case
+--  they have no effect (they do NOT cause the tasking runtime to be loaded).
+
+--  Note: this package is in the System hierarchy so that it can be directly
+--  be used by other predefined packages. User access to this package is via
+--  a renaming of this package in GNAT.Task_Lock (file g-tasloc.ads).
+
+package System.Task_Lock is
+   pragma Preelaborate;
+
+   procedure Lock;
+   pragma Inline (Lock);
+   --  Acquires the global lock, starts the execution of a critical region
+   --  which no other task can enter until the locking task calls Unlock
+
+   procedure Unlock;
+   pragma Inline (Unlock);
+   --  Releases the global lock, allowing another task to successfully
+   --  complete a Lock operation. Terminates the critical region.
+   --
+   --  The recommended protocol for using these two procedures is as
+   --  follows:
+   --
+   --    Locked_Processing : begin
+   --       Lock;
+   --       ...
+   --       TSL.Unlock;
+   --
+   --    exception
+   --       when others =>
+   --          Unlock;
+   --          raise;
+   --    end Locked_Processing;
+   --
+   --  This ensures that the lock is not left set if an exception is raised
+   --  explicitly or implicitly during the critical locked region.
+   --
+   --  Note on multiple calls to Lock: It is permissible to call Lock
+   --  more than once with no intervening Unlock from a single task,
+   --  and the lock will not be released until the corresponding number
+   --  of Unlock operations has been performed. For example:
+   --
+   --    System.Task_Lock.Lock;     -- acquires lock
+   --    System.Task_Lock.Lock;     -- no effect
+   --    System.Task_Lock.Lock;     -- no effect
+   --    System.Task_Lock.Unlock;   -- no effect
+   --    System.Task_Lock.Unlock;   -- no effect
+   --    System.Task_Lock.Unlock;   -- releases lock
+   --
+   --  However, as previously noted, the Task_Lock facility should only
+   --  be used for very local locks where the probability of conflict is
+   --  low, so usually this kind of nesting is not a good idea in any case.
+   --  In more complex locking situations, it is more appropriate to define
+   --  an appropriate protected type to provide the required locking.
+   --
+   --  It is an error to call Unlock when there has been no prior call to
+   --  Lock. The effect of such an erroneous call is undefined, and may
+   --  result in deadlock, or other malfunction of the run-time system.
+
+end System.Task_Lock;