--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/ada/libgnat/s-traceb.adb	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,118 @@
+------------------------------------------------------------------------------
+--                                                                          --
+--                         GNAT COMPILER COMPONENTS                         --
+--                                                                          --
+--                     S Y S T E M . T R A C E B A C K                      --
+--                                                                          --
+--                                 B o d y                                  --
+--                                                                          --
+--          Copyright (C) 1999-2017, Free Software Foundation, Inc.         --
+--                                                                          --
+-- 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 is the default version of this package
+
+--  Note: this unit must be compiled using -fno-optimize-sibling-calls.
+--  See comment below in body of Call_Chain for details on the reason.
+
+pragma Compiler_Unit_Warning;
+
+package body System.Traceback is
+
+   procedure Call_Chain
+     (Traceback   : System.Address;
+      Max_Len     : Natural;
+      Len         : out Natural;
+      Exclude_Min : System.Address := System.Null_Address;
+      Exclude_Max : System.Address := System.Null_Address;
+      Skip_Frames : Natural := 1);
+   --  Same as the exported version, but takes Traceback as an Address
+
+   ------------------
+   -- C_Call_Chain --
+   ------------------
+
+   function C_Call_Chain
+     (Traceback : System.Address;
+      Max_Len   : Natural) return Natural
+   is
+      Val : Natural;
+   begin
+      Call_Chain (Traceback, Max_Len, Val);
+      return Val;
+   end C_Call_Chain;
+
+   ----------------
+   -- Call_Chain --
+   ----------------
+
+   function Backtrace
+     (Traceback   : System.Address;
+      Len         : Integer;
+      Exclude_Min : System.Address;
+      Exclude_Max : System.Address;
+      Skip_Frames : Integer)
+      return        Integer;
+   pragma Import (C, Backtrace, "__gnat_backtrace");
+
+   procedure Call_Chain
+     (Traceback   : System.Address;
+      Max_Len     : Natural;
+      Len         : out Natural;
+      Exclude_Min : System.Address := System.Null_Address;
+      Exclude_Max : System.Address := System.Null_Address;
+      Skip_Frames : Natural := 1)
+   is
+   begin
+      --  Note: Backtrace relies on the following call actually creating a
+      --  stack frame. To ensure that this is the case, it is essential to
+      --  compile this unit without sibling call optimization.
+
+      --  We want the underlying engine to skip its own frame plus the
+      --  ones we have been requested to skip ourselves.
+
+      Len := Backtrace (Traceback   => Traceback,
+                        Len         => Max_Len,
+                        Exclude_Min => Exclude_Min,
+                        Exclude_Max => Exclude_Max,
+                        Skip_Frames => Skip_Frames + 1);
+   end Call_Chain;
+
+   procedure Call_Chain
+     (Traceback   : in out System.Traceback_Entries.Tracebacks_Array;
+      Max_Len     : Natural;
+      Len         : out Natural;
+      Exclude_Min : System.Address := System.Null_Address;
+      Exclude_Max : System.Address := System.Null_Address;
+      Skip_Frames : Natural := 1)
+   is
+   begin
+      Call_Chain
+        (Traceback'Address, Max_Len, Len,
+         Exclude_Min, Exclude_Max,
+
+         --  Skip one extra frame to skip the other Call_Chain entry as well
+
+         Skip_Frames => Skip_Frames + 1);
+   end Call_Chain;
+
+end System.Traceback;