gcc/ada/s-mastop-tru64.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                     SYSTEM.MACHINE_STATE_OPERATIONS                      --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                         (Version for Alpha/Dec Unix)                     --
   9 --                                                                          --
  10 --                     Copyright (C) 1999-2005, AdaCore                     --
  11 --                                                                          --
  12 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  13 -- terms of the  GNU General Public License as published  by the Free Soft- --
  14 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  15 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  16 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  17 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  18 -- for  more details.  You should have  received  a copy of the GNU General --
  19 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  20 -- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --
  21 -- Boston, MA 02110-1301, USA.                                              --
  22 --                                                                          --
  23 -- As a special exception,  if other files  instantiate  generics from this --
  24 -- unit, or you link  this unit with other files  to produce an executable, --
  25 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  26 -- covered  by the  GNU  General  Public  License.  This exception does not --
  27 -- however invalidate  any other reasons why  the executable file  might be --
  28 -- covered by the  GNU Public License.                                      --
  29 --                                                                          --
  30 -- GNAT was originally developed  by the GNAT team at  New York University. --
  31 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  32 --                                                                          --
  33 ------------------------------------------------------------------------------
  34
  35 --  This version of System.Machine_State_Operations is for use on
  36 --  Alpha systems running DEC Unix.
  37
  38 with System.Memory;
  39
  40 package body System.Machine_State_Operations is
  41
  42    pragma Linker_Options ("-lexc");
  43    --  Needed for definitions of exc_capture_context and exc_virtual_unwind
  44
  45    ----------------------------
  46    -- Allocate_Machine_State --
  47    ----------------------------
  48
  49    function Allocate_Machine_State return Machine_State is
  50       use System.Storage_Elements;
  51
  52       function c_machine_state_length return Storage_Offset;
  53       pragma Import (C, c_machine_state_length, "__gnat_machine_state_length");
  54
  55    begin
  56       return Machine_State
  57         (Memory.Alloc (Memory.size_t (c_machine_state_length)));
  58    end Allocate_Machine_State;
  59
  60    ----------------
  61    -- Fetch_Code --
  62    ----------------
  63
  64    function Fetch_Code (Loc : Code_Loc) return Code_Loc is
  65    begin
  66       return Loc;
  67    end Fetch_Code;
  68
  69    ------------------------
  70    -- Free_Machine_State --
  71    ------------------------
  72
  73    procedure Free_Machine_State (M : in out Machine_State) is
  74    begin
  75       Memory.Free (Address (M));
  76       M := Machine_State (Null_Address);
  77    end Free_Machine_State;
  78
  79    ------------------
  80    -- Get_Code_Loc --
  81    ------------------
  82
  83    function Get_Code_Loc (M : Machine_State) return Code_Loc is
  84       Asm_Call_Size : constant := 4;
  85
  86       function c_get_code_loc (M : Machine_State) return Code_Loc;
  87       pragma Import (C, c_get_code_loc, "__gnat_get_code_loc");
  88
  89       --  Code_Loc returned by c_get_code_loc is the return point but here we
  90       --  want Get_Code_Loc to return the call point. Under DEC Unix a call
  91       --  asm instruction takes 4 bytes. So we must remove this value from
  92       --  c_get_code_loc to have the call point.
  93
  94       Loc : constant Code_Loc := c_get_code_loc (M);
  95
  96    begin
  97       if Loc = 0 then
  98          return 0;
  99       else
 100          return Loc - Asm_Call_Size;
 101       end if;
 102    end Get_Code_Loc;
 103
 104    --------------------------
 105    -- Machine_State_Length --
 106    --------------------------
 107
 108    function Machine_State_Length
 109      return System.Storage_Elements.Storage_Offset
 110    is
 111       use System.Storage_Elements;
 112
 113       function c_machine_state_length return Storage_Offset;
 114       pragma Import (C, c_machine_state_length, "__gnat_machine_state_length");
 115
 116    begin
 117       return c_machine_state_length;
 118    end Machine_State_Length;
 119
 120    ---------------
 121    -- Pop_Frame --
 122    ---------------
 123
 124    procedure Pop_Frame (M : Machine_State) is
 125       procedure exc_virtual_unwind (Fcn : System.Address; M : Machine_State);
 126       pragma Import (C, exc_virtual_unwind, "exc_virtual_unwind");
 127
 128       function exc_lookup_function (Loc : Code_Loc) return System.Address;
 129       pragma Import (C, exc_lookup_function, "exc_lookup_function_entry");
 130
 131       procedure c_set_code_loc (M : Machine_State; Loc : Code_Loc);
 132       pragma Import (C, c_set_code_loc, "__gnat_set_code_loc");
 133
 134       --  Look for a code-range descriptor table containing the PC of the
 135       --  specified machine state. If we don't find any, attempting to unwind
 136       --  further would fail so we set the machine state's code location to a
 137       --  value indicating that the top of the call chain is reached. This
 138       --  happens when the function at the address pointed to by PC has not
 139       --  been registered with the unwinding machinery, as with the __istart
 140       --  functions generated by the linker in presence of initialization
 141       --  routines for example.
 142
 143       Prf : constant System.Address := exc_lookup_function (Get_Code_Loc (M));
 144
 145    begin
 146       if Prf = System.Null_Address then
 147          c_set_code_loc (M, 0);
 148       else
 149          exc_virtual_unwind (Prf, M);
 150       end if;
 151    end Pop_Frame;
 152
 153    -----------------------
 154    -- Set_Machine_State --
 155    -----------------------
 156
 157    procedure Set_Machine_State (M : Machine_State) is
 158       procedure c_capture_context (M : Machine_State);
 159       pragma Import (C, c_capture_context, "exc_capture_context");
 160    begin
 161       c_capture_context (M);
 162       Pop_Frame (M);
 163    end Set_Machine_State;
 164
 165 end System.Machine_State_Operations;