2010-07-27 Paolo Carlini <paolo.carlini@oracle.com>
[official-gcc/alias-decl.git] / gcc / ada / s-mastop.ads
blob74ff217c693723dcac506b3ad48e63cf5fb75a65
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- SYSTEM.MACHINE_STATE_OPERATIONS --
6 -- --
7 -- S p e c --
8 -- --
9 -- Copyright (C) 1999-2009, 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 3, 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. --
17 -- --
18 -- As a special exception under Section 7 of GPL version 3, you are granted --
19 -- additional permissions described in the GCC Runtime Library Exception, --
20 -- version 3.1, as published by the Free Software Foundation. --
21 -- --
22 -- You should have received a copy of the GNU General Public License and --
23 -- a copy of the GCC Runtime Library Exception along with this program; --
24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
25 -- <http://www.gnu.org/licenses/>. --
26 -- --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
29 -- --
30 ------------------------------------------------------------------------------
32 pragma Compiler_Unit;
34 pragma Polling (Off);
35 -- We must turn polling off for this unit, because otherwise we get
36 -- elaboration circularities with System.Exception_Tables.
38 with System.Storage_Elements;
40 package System.Machine_State_Operations is
42 subtype Code_Loc is System.Address;
43 -- Code location used in building exception tables and for call
44 -- addresses when propagating an exception (also traceback table)
45 -- Values of this type are created by using Label'Address or
46 -- extracted from machine states using Get_Code_Loc.
48 type Machine_State is new System.Address;
49 -- The table based exception handling approach (see a-except.adb) isolates
50 -- the target dependent aspects using an abstract data type interface
51 -- to the type Machine_State, which is represented as a System.Address
52 -- value (presumably implemented as a pointer to an appropriate record
53 -- structure).
55 function Machine_State_Length return System.Storage_Elements.Storage_Offset;
56 -- Function to determine the length of the Storage_Array needed to hold
57 -- a machine state. The machine state will always be maximally aligned.
58 -- The value returned is a constant that will be used to allocate space
59 -- for a machine state value.
61 function Allocate_Machine_State return Machine_State;
62 -- Allocate the required space for a Machine_State
64 procedure Free_Machine_State (M : in out Machine_State);
65 -- Free the dynamic memory taken by Machine_State
67 -- The initial value of type Machine_State is created by the low level
68 -- routine that actually raises an exception using the special builtin
69 -- _builtin_machine_state. This value will typically encode the value
70 -- of the program counter, and relevant registers. The following
71 -- operations are defined on Machine_State values:
73 function Get_Code_Loc (M : Machine_State) return Code_Loc;
74 -- This function extracts the program counter value from a machine
75 -- state, which the caller uses for searching the exception tables,
76 -- and also for recording entries in the traceback table. The call
77 -- returns a value of Null_Loc if the machine state represents the
78 -- outer level, or some other frame for which no information can be
79 -- provided.
81 procedure Pop_Frame (M : Machine_State);
82 -- This procedure pops the machine state M so that it represents the
83 -- call point, as though the current subprogram had returned. It
84 -- changes only the value referenced by M, and does not affect
85 -- the current stack environment.
87 function Fetch_Code (Loc : Code_Loc) return Code_Loc;
88 -- Some architectures (notably VMS) use a descriptor to describe
89 -- a subprogram address. This function computes the actual starting
90 -- address of the code from Loc.
92 -- ??? This function will go away when 'Code_Address is fixed on VMS.
94 -- Do not add pragma Inline to this function: there is a curious
95 -- interaction between rtsfind and front-end inlining. The exception
96 -- declaration in s-auxdec calls rtsfind, which forces several other system
97 -- packages to be compiled. Some of those have a pragma Inline, and we
98 -- compile the corresponding bodies so that inlining can take place. One
99 -- of these packages is s-mastop, which depends on s-auxdec, which is still
100 -- being compiled: we have not seen all the declarations in it yet, so we
101 -- get confused semantic errors.
103 procedure Set_Machine_State (M : Machine_State);
104 -- This routine sets M from the current machine state. It is called
105 -- when an exception is initially signalled to initialize the state.
107 end System.Machine_State_Operations;