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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- SYSTEM.MACHINE_STATE_OPERATIONS --
-- --
-- S p e c --
-- --
-- Copyright (C) 1999-2009, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception, --
-- version 3.1, as published by the Free Software Foundation. --
-- --
-- You should have received a copy of the GNU General Public License and --
-- a copy of the GCC Runtime Library Exception along with this program; --
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
-- <http://www.gnu.org/licenses/>. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
pragma Compiler_Unit;
pragma Polling (Off);
-- We must turn polling off for this unit, because otherwise we get
-- elaboration circularities with System.Exception_Tables.
with System.Storage_Elements;
package System.Machine_State_Operations is
subtype Code_Loc is System.Address;
-- Code location used in building exception tables and for call
-- addresses when propagating an exception (also traceback table)
-- Values of this type are created by using Label'Address or
-- extracted from machine states using Get_Code_Loc.
type Machine_State is new System.Address;
-- The table based exception handling approach (see a-except.adb) isolates
-- the target dependent aspects using an abstract data type interface
-- to the type Machine_State, which is represented as a System.Address
-- value (presumably implemented as a pointer to an appropriate record
-- structure).
function Machine_State_Length return System.Storage_Elements.Storage_Offset;
-- Function to determine the length of the Storage_Array needed to hold
-- a machine state. The machine state will always be maximally aligned.
-- The value returned is a constant that will be used to allocate space
-- for a machine state value.
function Allocate_Machine_State return Machine_State;
-- Allocate the required space for a Machine_State
procedure Free_Machine_State (M : in out Machine_State);
-- Free the dynamic memory taken by Machine_State
-- The initial value of type Machine_State is created by the low level
-- routine that actually raises an exception using the special builtin
-- _builtin_machine_state. This value will typically encode the value
-- of the program counter, and relevant registers. The following
-- operations are defined on Machine_State values:
function Get_Code_Loc (M : Machine_State) return Code_Loc;
-- This function extracts the program counter value from a machine
-- state, which the caller uses for searching the exception tables,
-- and also for recording entries in the traceback table. The call
-- returns a value of Null_Loc if the machine state represents the
-- outer level, or some other frame for which no information can be
-- provided.
procedure Pop_Frame (M : Machine_State);
-- This procedure pops the machine state M so that it represents the
-- call point, as though the current subprogram had returned. It
-- changes only the value referenced by M, and does not affect
-- the current stack environment.
function Fetch_Code (Loc : Code_Loc) return Code_Loc;
-- Some architectures (notably VMS) use a descriptor to describe
-- a subprogram address. This function computes the actual starting
-- address of the code from Loc.
--
-- ??? This function will go away when 'Code_Address is fixed on VMS.
--
-- Do not add pragma Inline to this function: there is a curious
-- interaction between rtsfind and front-end inlining. The exception
-- declaration in s-auxdec calls rtsfind, which forces several other system
-- packages to be compiled. Some of those have a pragma Inline, and we
-- compile the corresponding bodies so that inlining can take place. One
-- of these packages is s-mastop, which depends on s-auxdec, which is still
-- being compiled: we have not seen all the declarations in it yet, so we
-- get confused semantic errors.
procedure Set_Machine_State (M : Machine_State);
-- This routine sets M from the current machine state. It is called
-- when an exception is initially signalled to initialize the state.
end System.Machine_State_Operations;
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