--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/ada/libgnat/s-stchop.adb	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,279 @@
+------------------------------------------------------------------------------
+--                                                                          --
+--                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --
+--                                                                          --
+--     S Y S T E M . S T A C K _ C H E C K I N G . O P E R A T I O N S      --
+--                                                                          --
+--                                  B o d y                                 --
+--                                                                          --
+--          Copyright (C) 1999-2017, Free Software Foundation, Inc.         --
+--                                                                          --
+-- GNARL 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/>.                                          --
+--                                                                          --
+-- GNARL was developed by the GNARL team at Florida State University.       --
+-- Extensive contributions were provided by Ada Core Technologies, Inc.     --
+--                                                                          --
+------------------------------------------------------------------------------
+
+--  This is the general implementation of this package. There is a VxWorks
+--  specific version of this package (s-stchop-vxworks.adb). This file should
+--  be kept synchronized with it.
+
+pragma Restrictions (No_Elaboration_Code);
+--  We want to guarantee the absence of elaboration code because the
+--  binder does not handle references to this package.
+
+with System.Storage_Elements; use System.Storage_Elements;
+with System.Parameters; use System.Parameters;
+with System.Soft_Links;
+with System.CRTL;
+
+package body System.Stack_Checking.Operations is
+
+   Kilobyte : constant := 1024;
+
+   function Set_Stack_Info
+     (Stack : not null access Stack_Access) return Stack_Access;
+   --  The function Set_Stack_Info is the actual function that updates the
+   --  cache containing a pointer to the Stack_Info. It may also be used for
+   --  detecting asynchronous abort in combination with Invalidate_Self_Cache.
+   --
+   --  Set_Stack_Info should do the following things in order:
+   --     1) Get the Stack_Access value for the current task
+   --     2) Set Stack.all to the value obtained in 1)
+   --     3) Optionally Poll to check for asynchronous abort
+   --
+   --  This order is important because if at any time a write to the stack
+   --  cache is pending, that write should be followed by a Poll to prevent
+   --  losing signals.
+   --
+   --  Note: This function must be compiled with Polling turned off
+   --
+   --  Note: on systems with real thread-local storage, Set_Stack_Info should
+   --  return an access value for such local storage. In those cases the cache
+   --  will always be up-to-date.
+
+   ----------------------------
+   -- Invalidate_Stack_Cache --
+   ----------------------------
+
+   procedure Invalidate_Stack_Cache (Any_Stack : Stack_Access) is
+      pragma Warnings (Off, Any_Stack);
+   begin
+      Cache := Null_Stack;
+   end Invalidate_Stack_Cache;
+
+   -----------------------------
+   -- Notify_Stack_Attributes --
+   -----------------------------
+
+   procedure Notify_Stack_Attributes
+     (Initial_SP : System.Address;
+      Size       : System.Storage_Elements.Storage_Offset)
+   is
+      My_Stack : constant Stack_Access := Soft_Links.Get_Stack_Info.all;
+
+      --  We piggyback on the 'Limit' field to store what will be used as the
+      --  'Base' and leave the 'Size' alone to not interfere with the logic in
+      --  Set_Stack_Info below.
+
+      pragma Unreferenced (Size);
+
+   begin
+      My_Stack.Limit := Initial_SP;
+   end Notify_Stack_Attributes;
+
+   --------------------
+   -- Set_Stack_Info --
+   --------------------
+
+   function Set_Stack_Info
+     (Stack : not null access Stack_Access) return Stack_Access
+   is
+      type Frame_Mark is null record;
+      Frame_Location : Frame_Mark;
+      Frame_Address  : constant Address := Frame_Location'Address;
+
+      My_Stack    : Stack_Access;
+      Limit_Chars : System.Address;
+      Limit       : Integer;
+
+   begin
+      --  The order of steps 1 .. 3 is important, see specification
+
+      --  1) Get the Stack_Access value for the current task
+
+      My_Stack := Soft_Links.Get_Stack_Info.all;
+
+      if My_Stack.Base = Null_Address then
+
+         --  First invocation, initialize based on the assumption that there
+         --  are Environment_Stack_Size bytes available beyond the current
+         --  frame address.
+
+         if My_Stack.Size = 0 then
+            My_Stack.Size := Storage_Offset (Default_Env_Stack_Size);
+
+            --  When the environment variable GNAT_STACK_LIMIT is set, set
+            --  Environment_Stack_Size to that number of kB.
+
+            Limit_Chars := System.CRTL.getenv ("GNAT_STACK_LIMIT" & ASCII.NUL);
+
+            if Limit_Chars /= Null_Address then
+               Limit := System.CRTL.atoi (Limit_Chars);
+
+               if Limit >= 0 then
+                  My_Stack.Size := Storage_Offset (Limit) * Kilobyte;
+               end if;
+            end if;
+         end if;
+
+         --  If a stack base address has been registered, honor it. Fallback to
+         --  the address of a local object otherwise.
+
+         My_Stack.Base :=
+           (if My_Stack.Limit /= System.Null_Address
+            then My_Stack.Limit else Frame_Address);
+
+         if Stack_Grows_Down then
+
+            --  Prevent wrap-around on too big stack sizes
+
+            My_Stack.Limit := My_Stack.Base - My_Stack.Size;
+
+            if My_Stack.Limit > My_Stack.Base then
+               My_Stack.Limit := Address'First;
+            end if;
+
+         else
+            My_Stack.Limit := My_Stack.Base + My_Stack.Size;
+
+            --  Prevent wrap-around on too big stack sizes
+
+            if My_Stack.Limit < My_Stack.Base then
+               My_Stack.Limit := Address'Last;
+            end if;
+         end if;
+      end if;
+
+      --  2) Set Stack.all to the value obtained in 1)
+
+      Stack.all := My_Stack;
+
+      --  3) Optionally Poll to check for asynchronous abort
+
+      if Soft_Links.Check_Abort_Status.all /= 0 then
+         raise Standard'Abort_Signal;
+      end if;
+
+      --  Never trust the cached value, but return local copy
+
+      return My_Stack;
+   end Set_Stack_Info;
+
+   -----------------
+   -- Stack_Check --
+   -----------------
+
+   function Stack_Check
+     (Stack_Address : System.Address) return Stack_Access
+   is
+      type Frame_Marker is null record;
+      Marker        : Frame_Marker;
+      Cached_Stack  : constant Stack_Access := Cache;
+      Frame_Address : constant System.Address := Marker'Address;
+
+   begin
+      --  The parameter may have wrapped around in System.Address arithmetics.
+      --  In that case, we have no other choices than raising the exception.
+
+      if (Stack_Grows_Down and then
+            Stack_Address > Frame_Address)
+        or else
+         (not Stack_Grows_Down and then
+            Stack_Address < Frame_Address)
+      then
+         raise Storage_Error with "stack overflow detected";
+      end if;
+
+      --  This function first does a "cheap" check which is correct if it
+      --  succeeds. In case of failure, the full check is done. Ideally the
+      --  cheap check should be done in an optimized manner, or be inlined.
+
+      if (Stack_Grows_Down and then
+            (Frame_Address <= Cached_Stack.Base
+               and then
+             Stack_Address > Cached_Stack.Limit))
+        or else
+         (not Stack_Grows_Down and then
+            (Frame_Address >= Cached_Stack.Base
+               and then
+             Stack_Address < Cached_Stack.Limit))
+      then
+         --  Cached_Stack is valid as it passed the stack check
+
+         return Cached_Stack;
+      end if;
+
+      Full_Check :
+      declare
+         My_Stack : constant Stack_Access := Set_Stack_Info (Cache'Access);
+         --  At this point Stack.all might already be invalid, so
+         --  it is essential to use our local copy of Stack.
+
+      begin
+         if (Stack_Grows_Down and then
+               (not (Frame_Address <= My_Stack.Base)))
+           or else
+            (not Stack_Grows_Down and then
+               (not (Frame_Address >= My_Stack.Base)))
+         then
+            --  The returned Base is lower than the stored one, so assume that
+            --  the original one wasn't right and use the current Frame_Address
+            --  as new one. This allows Base to be initialized with the
+            --  Frame_Address as approximation. During initialization the
+            --  Frame_Address will be close to the stack base anyway: the
+            --  difference should be compensated for in the stack reserve.
+
+            My_Stack.Base := Frame_Address;
+         end if;
+
+         if (Stack_Grows_Down
+              and then Stack_Address < My_Stack.Limit)
+           or else
+            (not Stack_Grows_Down
+              and then Stack_Address > My_Stack.Limit)
+         then
+            raise Storage_Error with "stack overflow detected";
+         end if;
+
+         return My_Stack;
+      end Full_Check;
+   end Stack_Check;
+
+   ------------------------
+   -- Update_Stack_Cache --
+   ------------------------
+
+   procedure Update_Stack_Cache (Stack : Stack_Access) is
+   begin
+      if not Multi_Processor then
+         Cache := Stack;
+      end if;
+   end Update_Stack_Cache;
+
+end System.Stack_Checking.Operations;