gcc/ada/a-exexpr.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --  A D A . E X C E P T I O N S . E X C E P T I O N _ P R O P A G A T I O N --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2005 Free Software Foundation, Inc.          --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  19 -- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --
  20 -- Boston, MA 02110-1301, USA.                                              --
  21 --                                                                          --
  22 -- As a special exception,  if other files  instantiate  generics from this --
  23 -- unit, or you link  this unit with other files  to produce an executable, --
  24 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  29 -- GNAT was originally developed  by the GNAT team at  New York University. --
  30 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 --  This is the default version, using the __builtin_setjmp/longjmp EH
  35 --  mechanism.
  36
  37 with System.Storage_Elements;  use System.Storage_Elements;
  38
  39 pragma Warnings (Off);
  40 --  Since several constructs give warnings in 3.14a1, including unreferenced
  41 --  variables and pragma Unreferenced itself.
  42
  43 separate (Ada.Exceptions)
  44 package body Exception_Propagation is
  45
  46    procedure builtin_longjmp (buffer : Address; Flag : Integer);
  47    pragma No_Return (builtin_longjmp);
  48    pragma Import (C, builtin_longjmp, "_gnat_builtin_longjmp");
  49
  50    ---------------------
  51    -- Setup_Exception --
  52    ---------------------
  53
  54    procedure Setup_Exception
  55      (Excep    : EOA;
  56       Current  : EOA;
  57       Reraised : Boolean := False)
  58    is
  59       pragma Unreferenced (Excep, Current, Reraised);
  60    begin
  61       --  In the GNAT-SJLJ case this "stack" only exists implicitely, by way of
  62       --  local occurrence declarations together with save/restore operations
  63       --  generated by the front-end, and this routine has nothing to do.
  64
  65       null;
  66    end Setup_Exception;
  67
  68    -------------------------
  69    -- Propagate_Exception --
  70    -------------------------
  71
  72    procedure Propagate_Exception (From_Signal_Handler : Boolean) is
  73       Jumpbuf_Ptr : constant Address := Get_Jmpbuf_Address.all;
  74       Excep       : constant EOA := Get_Current_Excep.all;
  75    begin
  76       --  Compute the backtrace for this occurrence if corresponding binder
  77       --  option has been set. Call_Chain takes care of the reraise case.
  78
  79       Call_Chain (Excep);
  80
  81       --  Note on above call to Call_Chain:
  82
  83       --  We used to only do this if From_Signal_Handler was not set,
  84       --  based on the assumption that backtracing from a signal handler
  85       --  would not work due to stack layout oddities. However, since
  86
  87       --   1. The flag is never set in tasking programs (Notify_Exception
  88       --      performs regular raise statements), and
  89
  90       --   2. No problem has shown up in tasking programs around here so
  91       --      far, this turned out to be too strong an assumption.
  92
  93       --  As, in addition, the test was
  94
  95       --   1. preventing the production of backtraces in non-tasking
  96       --      programs, and
  97
  98       --   2. introducing a behavior inconsistency between
  99       --      the tasking and non-tasking cases,
 100
 101       --  we have simply removed it
 102
 103       --  If the jump buffer pointer is non-null, transfer control using
 104       --  it. Otherwise announce an unhandled exception (note that this
 105       --  means that we have no finalizations to do other than at the outer
 106       --  level). Perform the necessary notification tasks in both cases.
 107
 108       if Jumpbuf_Ptr /= Null_Address then
 109          if not Excep.Exception_Raised then
 110             Excep.Exception_Raised := True;
 111             Exception_Traces.Notify_Handled_Exception;
 112          end if;
 113
 114          builtin_longjmp (Jumpbuf_Ptr, 1);
 115
 116       else
 117          Exception_Traces.Notify_Unhandled_Exception;
 118          Exception_Traces.Unhandled_Exception_Terminate;
 119       end if;
 120    end Propagate_Exception;
 121
 122 end Exception_Propagation;