1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
5 -- SYSTEM.MACHINE_STATE_OPERATIONS --
9 -- Copyright (C) 1999-2009, Free Software Foundation, Inc. --
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. --
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. --
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/>. --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
30 ------------------------------------------------------------------------------
32 pragma Warnings (Off);
37 -- We must turn polling off for this unit, because otherwise we get
38 -- elaboration circularities with System.Exception_Tables.
40 with System.Storage_Elements;
42 package System.Machine_State_Operations is
44 subtype Code_Loc is System.Address;
45 -- Code location used in building exception tables and for call
46 -- addresses when propagating an exception (also traceback table)
47 -- Values of this type are created by using Label'Address or
48 -- extracted from machine states using Get_Code_Loc.
50 type Machine_State is new System.Address;
51 -- The table based exception handling approach (see a-except.adb) isolates
52 -- the target dependent aspects using an abstract data type interface
53 -- to the type Machine_State, which is represented as a System.Address
54 -- value (presumably implemented as a pointer to an appropriate record
57 function Machine_State_Length return System.Storage_Elements.Storage_Offset;
58 -- Function to determine the length of the Storage_Array needed to hold
59 -- a machine state. The machine state will always be maximally aligned.
60 -- The value returned is a constant that will be used to allocate space
61 -- for a machine state value.
63 function Allocate_Machine_State return Machine_State;
64 -- Allocate the required space for a Machine_State
66 procedure Free_Machine_State (M : in out Machine_State);
67 -- Free the dynamic memory taken by Machine_State
69 -- The initial value of type Machine_State is created by the low level
70 -- routine that actually raises an exception using the special builtin
71 -- _builtin_machine_state. This value will typically encode the value
72 -- of the program counter, and relevant registers. The following
73 -- operations are defined on Machine_State values:
75 function Get_Code_Loc (M : Machine_State) return Code_Loc;
76 -- This function extracts the program counter value from a machine
77 -- state, which the caller uses for searching the exception tables,
78 -- and also for recording entries in the traceback table. The call
79 -- returns a value of Null_Loc if the machine state represents the
80 -- outer level, or some other frame for which no information can be
83 procedure Pop_Frame (M : Machine_State);
84 -- This procedure pops the machine state M so that it represents the
85 -- call point, as though the current subprogram had returned. It
86 -- changes only the value referenced by M, and does not affect
87 -- the current stack environment.
89 function Fetch_Code (Loc : Code_Loc) return Code_Loc;
90 -- Some architectures (notably VMS) use a descriptor to describe
91 -- a subprogram address. This function computes the actual starting
92 -- address of the code from Loc.
94 -- ??? This function will go away when 'Code_Address is fixed on VMS.
96 -- Do not add pragma Inline to this function: there is a curious
97 -- interaction between rtsfind and front-end inlining. The exception
98 -- declaration in s-auxdec calls rtsfind, which forces several other system
99 -- packages to be compiled. Some of those have a pragma Inline, and we
100 -- compile the corresponding bodies so that inlining can take place. One
101 -- of these packages is s-mastop, which depends on s-auxdec, which is still
102 -- being compiled: we have not seen all the declarations in it yet, so we
103 -- get confused semantic errors.
105 procedure Set_Machine_State (M : Machine_State);
106 -- This routine sets M from the current machine state. It is called
107 -- when an exception is initially signalled to initialize the state.
109 end System.Machine_State_Operations;