------------------------------------------------------------------------------ -- -- -- 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 -- -- . -- -- -- -- 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;