1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- SYSTEM.MACHINE_STATE_OPERATIONS -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 1999-2013, 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------------------------------------------------------------------------------ 31 32pragma Compiler_Unit_Warning; 33 34pragma Polling (Off); 35-- We must turn polling off for this unit, because otherwise we get 36-- elaboration circularities with System.Exception_Tables. 37 38with System.Storage_Elements; 39 40package System.Machine_State_Operations is 41 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. 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 70 -- of the program counter, and relevant registers. The following 71 -- operations 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 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. 80 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. 86 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. 91 -- 92 -- ??? This function will go away when 'Code_Address is fixed on VMS. 93 -- 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. 102 103 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. 106 107end System.Machine_State_Operations; 108