New Language: Ada

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@45957 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 179 insertions, 0 deletions

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+------------------------------------------------------------------------------
+--                                                                          --
+--                 GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS              --
+--                                                                          --
+--                  S Y S T E M . T A S K I N G . D E B U G                 --
+--                                                                          --
+--                                  S p e c                                 --
+--                                                                          --
+--                             $Revision: 1.16 $
+--                                                                          --
+--          Copyright (C) 1997-1998, 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 2,  or (at your option) any later ver- --
+-- sion. GNARL 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.  See the GNU General Public License --
+-- for  more details.  You should have  received  a copy of the GNU General --
+-- Public License  distributed with GNARL; see file COPYING.  If not, write --
+-- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
+-- MA 02111-1307, USA.                                                      --
+--                                                                          --
+-- As a special exception,  if other files  instantiate  generics from this --
+-- unit, or you link  this unit with other files  to produce an executable, --
+-- this  unit  does not  by itself cause  the resulting  executable  to  be --
+-- covered  by the  GNU  General  Public  License.  This exception does not --
+-- however invalidate  any other reasons why  the executable file  might be --
+-- covered by the  GNU Public License.                                      --
+--                                                                          --
+-- GNARL was developed by the GNARL team at Florida State University. It is --
+-- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
+-- State University (http://www.gnat.com).                                  --
+--                                                                          --
+------------------------------------------------------------------------------
+
+--  This package encapsulates all direct interfaces to task debugging services
+--  that are needed by gdb with gnat mode (1.17 and higher)
+
+with Interfaces.C;
+with System.Tasking;
+with System.OS_Interface;
+
+package System.Tasking.Debug is
+
+   subtype int is Interfaces.C.int;
+   subtype unsigned_long is Interfaces.C.unsigned_long;
+
+   package ST renames System.Tasking;
+
+   Known_Tasks : array (0 .. 999) of Task_ID;
+   --  Global array of tasks read by gdb, and updated by
+   --  Create_Task and Finalize_TCB
+
+   procedure Task_Creation_Hook (Thread : OS_Interface.Thread_Id);
+   --  This procedure is used to notify VxGdb of task's creation.
+   --  It must be called by the task's creator.
+
+   procedure Task_Termination_Hook;
+   --  This procedure is used to notify VxGdb of task's termination.
+
+   function Self return Task_ID;
+   --  return system ID of current task
+
+   procedure List_Tasks;
+   --  Print a list of all the known Ada tasks with abbreviated state
+   --  information, one-per-line, to the standard output file
+
+   procedure Print_Current_Task;
+   procedure Print_Task_Info_Header;
+   procedure Print_Task_Info (T : Task_ID);
+   --  Write TASK_ID of current task, in hexadecimal, as one line, to
+   --  the standard output file
+   --
+   --  Beware that Print_Current_Task may print garbage during an early
+   --  stage of activation. There is a small window where a task is just
+   --  initializing itself and has not yet recorded its own task Id.
+   --
+   --  Beware that Print_Current_Task will either not work at all or print
+   --  garbage if it has interrupted a thread of control that does not
+   --  correspond to any Ada task. For example, this is could happen if
+   --  the debugger interrupts a signal handler that is using an alternate
+   --  stack, or interrupts the dispatcher in the underlying thread
+   --  implementation.
+
+   procedure Set_User_State (Value : Integer);
+
+   procedure Print_Accept_Info (T : Task_ID);
+
+   procedure Trace
+     (Self_ID  : Task_ID;
+      Msg      : String;
+      Other_ID : Task_ID;
+      Flag     : Character);
+
+   procedure Trace
+     (Self_ID : Task_ID;
+      Msg     : String;
+      Flag    : Character);
+
+   procedure Trace
+     (Msg  : String;
+      Flag : Character);
+
+   procedure Trace
+     (Msg      : String;
+      Other_ID : Task_ID;
+      Flag     : Character);
+
+   procedure Set_Trace
+     (Flag  : Character;
+      Value : Boolean := True);
+
+   function Image (T : Task_ID) return String;
+
+   procedure Suspend_All_Tasks (Thread_Self : OS_Interface.Thread_Id);
+   --  Suspend all the tasks except the one whose associated thread is
+   --  Thread_Self by traversing All_Tasks_Lists and calling
+   --  System.Task_Primitives.Operations.Suspend_Task
+   --  Such functionnality is needed by gdb on some targets (e.g VxWorks)
+   --  Warning: for efficiency purposes, there is no locking.
+
+   procedure Resume_All_Tasks (Thread_Self : OS_Interface.Thread_Id);
+   --  Resume all the tasks except the one whose associated thread is
+   --  Thread_Self by traversing All_Tasks_Lists and calling
+   --  System.Task_Primitives.Operations.Continue_Task
+   --  Such functionnality is needed by gdb on some targets (e.g VxWorks)
+   --  Warning: for efficiency purposes, there is no locking.
+
+end System.Tasking.Debug;
+
+-----------------------------
+-- Use of These Functions  --
+-----------------------------
+
+--  Calling complicated functions from the debugger is generally pretty
+--  risky, especially in a multithreaded program.
+
+--  The debugger may interrupt something that is not an Ada task,
+--  within the thread implementation, and which is not async-safe.
+
+--  For example, under Solaris, it can interrupt code in "_dynamiclwps",
+--  which seems to serve as dispatcher when all the user threads are
+--  suspended. By experience, we have found that one cannot safely
+--  do certain things, apparently including calls to thread primitives
+--  from the debugger if the debugger has interrupted at one of these
+--  unsafe points. In general, if you interrupt a running program
+--  asynchronously (e.g. via control-C), it will not be safe to
+--  call the subprograms in this package.
+
+-----------------
+-- Future work --
+-----------------
+
+--  It would be nice to be able to tell whether execution has been
+--  interrupted in an Ada task. A heuristic way of checking this would
+--  be if we added to the Ada TCB a component that always contains a
+--  constant value that is unlikely to occur accidentally in code or
+--  data. We could then check this in the debugger-callable subprograms,
+--  and simply return an error code if it looks unsafe to proceed.
+
+--  ???
+--  Recently we have added such a marker as a local variable of the
+--  task-wrapper routine. This allows Self to generate a fake ATCB for
+--  non-Ada threads of control. Given this capability, it is probably
+--  time to revisit the issue above.
+
+--  DEADLOCK
+
+--  We follow a simple rule here to avoid deadlock:
+
+--  We do not use any locks in functions called by gdb, and we do not
+--  traverse linked lists.
+--
+--  The use of an array (Known_Tasks) has many advantages:
+
+--   - Easy and fast to examine;
+--   - No risk of dangling references (to the next element) when traversing
+--     the array.