File : s-mastop.ads
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- SYSTEM.MACHINE_STATE_OPERATIONS --
6 -- --
7 -- S p e c --
8 -- --
9 -- Copyright (C) 1999-2014, 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 -- --
19 -- --
20 -- --
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 ------------------------------------------------------------------------------
31
32 pragma Compiler_Unit_Warning;
33
34 pragma Polling (Off);
35 -- We must turn polling off for this unit, because otherwise we get
36 -- elaboration circularities with System.Exception_Tables.
37
38 with System.Storage_Elements;
39
40 package System.Machine_State_Operations is
41
42 subtype Code_Loc is System.Address;
43 -- Code location used in building exception tables and for call addresses
44 -- when propagating an exception (also traceback table) Values of this
45 -- type are created by using Label'Address or extracted from machine
46 -- states using Get_Code_Loc.
47
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).
54
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.
60
61 function Allocate_Machine_State return Machine_State;
62 -- Allocate the required space for a Machine_State
63
64 procedure Free_Machine_State (M : in out Machine_State);
65 -- Free the dynamic memory taken by Machine_State
66
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 of
70 -- the program counter, and relevant registers. The following operations
71 -- are defined on Machine_State values:
72
73 function Get_Code_Loc (M : Machine_State) return Code_Loc;
74 -- This function extracts the program counter value from a machine state,
75 -- which the caller uses for searching the exception tables, and also for
76 -- recording entries in the traceback table. The call returns a value of
77 -- Null_Loc if the machine state represents the outer level, or some other
78 -- frame for which no information can be provided.
79
80 procedure Pop_Frame (M : Machine_State);
81 -- This procedure pops the machine state M so that it represents the
82 -- call point, as though the current subprogram had returned. It changes
83 -- only the value referenced by M, and does not affect the current stack
84 -- environment.
85
86 function Fetch_Code (Loc : Code_Loc) return Code_Loc;
87 -- Some architectures (notably HPUX) use a descriptor to describe a
88 -- subprogram address. This function computes the actual starting
89 -- address of the code from Loc.
90 --
91 -- Do not add pragma Inline to this function: there is a curious
92 -- interaction between rtsfind and front-end inlining. The exception
93 -- declaration in s-auxdec calls rtsfind, which forces several other system
94 -- packages to be compiled. Some of those have a pragma Inline, and we
95 -- compile the corresponding bodies so that inlining can take place. One
96 -- of these packages is s-mastop, which depends on s-auxdec, which is still
97 -- being compiled: we have not seen all the declarations in it yet, so we
98 -- get confused semantic errors ???
99
100 procedure Set_Machine_State (M : Machine_State);
101 -- This routine sets M from the current machine state. It is called when an
102 -- exception is initially signalled to initialize the state.
103
104 end System.Machine_State_Operations;