--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/ada/libgnat/s-traent.ads	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,67 @@
+------------------------------------------------------------------------------
+--                                                                          --
+--                         GNAT RUN-TIME COMPONENTS                         --
+--                                                                          --
+--              S Y S T E M . T R A C E B A C K _ E N T R I E S             --
+--                                                                          --
+--                                 S p e c                                  --
+--                                                                          --
+--          Copyright (C) 2003-2017, Free Software Foundation, Inc.         --
+--                                                                          --
+-- This specification is derived from the Ada Reference Manual for use with --
+-- GNAT. The copyright notice above, and the license provisions that follow --
+-- apply solely to the  contents of the part following the private keyword. --
+--                                                                          --
+-- 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.      --
+--                                                                          --
+------------------------------------------------------------------------------
+
+--  This package offers an abstraction of what is stored in traceback arrays
+--  for call-chain computation purposes. By default, as defined in this
+--  version of the package, an entry is a mere code location representing the
+--  address of a call instruction part of the call-chain.
+
+pragma Polling (Off);
+--  We must turn polling off for this unit, because otherwise we get
+--  elaboration circularities with Ada.Exceptions.
+
+pragma Compiler_Unit_Warning;
+
+package System.Traceback_Entries is
+   pragma Preelaborate;
+
+   subtype Traceback_Entry is System.Address;
+   --  This subtype defines what each traceback array entry contains
+
+   Null_TB_Entry : constant Traceback_Entry := System.Null_Address;
+   --  This is the value to be used when initializing an entry
+
+   type Tracebacks_Array is array (Positive range <>) of Traceback_Entry;
+
+   function PC_For (TB_Entry : Traceback_Entry) return System.Address;
+   pragma Inline (PC_For);
+   --  Returns the address of the call instruction associated with the
+   --  provided entry.
+
+   function TB_Entry_For (PC : System.Address) return Traceback_Entry;
+   pragma Inline (TB_Entry_For);
+   --  Returns an entry representing a frame for a call instruction at PC
+
+end System.Traceback_Entries;