diff options
Diffstat (limited to 'gcc/ada/targparm.ads')
| -rw-r--r-- | gcc/ada/targparm.ads | 397 |
1 files changed, 343 insertions, 54 deletions
diff --git a/gcc/ada/targparm.ads b/gcc/ada/targparm.ads index 7aff79d53f3..cf7aa2398ba 100644 --- a/gcc/ada/targparm.ads +++ b/gcc/ada/targparm.ads @@ -6,7 +6,7 @@ -- -- -- S p e c -- -- -- --- Copyright (C) 1999-2001 Free Software Foundation, Inc. -- +-- Copyright (C) 1999-2003 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- -- @@ -28,13 +28,18 @@ -- System, to indicate parameters relevant to the target environment. -- Conceptually, these parameters could be obtained using rtsfind, but --- we do not do this for three reasons: +-- we do not do this for four reasons: -- 1. Compiling System for every compilation wastes time + -- 2. This compilation impedes debugging by adding extra compile steps + -- 3. There are recursion problems coming from compiling System itself -- or any of its children. +-- 4. The binder also needs the parameters, and we do not want to have +-- to drag a lot of front end stuff into the binder. + -- For all these reasons, we read in the source of System, and then scan -- it at the text level to extract the parameter values. @@ -43,8 +48,109 @@ -- computed and set in the ali file. This partially negates points 1 and 2 -- above although just parsing is quick and does not impact debugging much. +-- The parameters acquired by this routine from system.ads fall into three +-- categories: + +-- 1. Configuration pragmas, that must appear at the start of the file. +-- Any such pragmas automatically apply to any unit compiled in the +-- presence of this system file. Only a limited set of such pragmas +-- may appear as documented in the corresponding section below, + +-- 2. Target parameters. These are boolean constants that are defined +-- in the private part of the package giving fixed information +-- about the target architecture, and the capabilities of the +-- code generator and run-time library. + +-- 3. Identification information. This is an optional string constant +-- that gives the name of the run-time library configuration. This +-- line may be ommitted for a version of system.ads to be used with +-- the full Ada 95 run time. + +with Rident; use Rident; +with Types; use Types; +with Uintp; use Uintp; + package Targparm is + --------------------------- + -- Configuration Pragmas -- + --------------------------- + + -- The following switches get set if the corresponding configuration + -- pragma is scanned from the source of system.ads. No other pragmas + -- are permitted to appear at the start of the system.ads source file. + + -- If a pragma Discard_Names appears, then Opt.Global_Discard_Names is + -- set to True to indicate that all units must be compiled in this mode. + + -- If a pragma Locking_Policy appears, then Opt.Locking_Policy is set + -- to the first character of the policy name, and Opt.Locking_Policy_Sloc + -- is set to System_Location. + + -- If a pragma Normalize_Scalars appears, then Opt.Normalize_Scalars + -- is set True, as well as Opt.Init_Or_Norm_Scalars. + + -- If a pragma Queuing_Policy appears, then Opt.Queuing_Policy is set + -- to the first character of the policy name, and Opt.Queuing_Policy_Sloc + -- is set to System_Location. + + -- If a pragma Task_Dispatching_Policy appears, then the flag + -- Opt.Task_Dispatching_Policy is set to the first character of the + -- policy name, and Opt.Task_Dispatching_Policy_Sloc is set to + -- System_Location. + + -- If a pragma Polling (On) appears, then the flag Opt.Polling_Required + -- is set to True. + + -- if a pragma Suppress_Exception_Locations appears, then the flag + -- Opt.Exception_Locations_Suppressed is set to True. + + -- The only other pragma allowed is a pragma Restrictions that gives the + -- simple name of a restriction for which partition consistency is always + -- required (see definition of Rident.Partition_Restrictions). + + Restrictions_On_Target : + array (Partition_Restrictions) of Boolean := (others => False); + -- Element is set True if a pragma Restrictions for the corresponding + -- identifier appears in system.ads. Note that only partition restriction + -- identifiers are permitted as arguments for pragma Restrictions for + -- pragmas appearing at the start of system.ads. + + Restriction_Parameters_On_Target : + array (Restriction_Parameter_Id) of Uint := (others => No_Uint); + -- Element is set to specified value if a pragma Restrictions for the + -- corresponding restriction parameter value is set. + + ------------------- + -- Run Time Name -- + ------------------- + + -- This parameter should be regarded as read only by all clients of + -- of package. The only way they get modified is by calling the + -- Get_Target_Parameters routine which reads the values from a provided + -- text buffer containing the source of the system package. + + -- The corresponding string constant is placed immediately at the start + -- of the private part of system.ads if is present, e.g. in the form: + + -- Run_Time_Name : constant String := "Zero Footprint Run Time"; + + -- the corresponding messages will look something like + + -- xxx not supported (Zero Footprint Run Time) + + Run_Time_Name_On_Target : Name_Id := No_Name; + -- Set to appropriate names table entry Id value if a Run_Time_Name + -- string constant is defined in system.ads. This name is used only + -- for the configurable run-time case, and is used to parametrize + -- messages that complain about non-supported run-time features. + -- The name should contain only letters A-Z, digits 1-9, spaces, + -- and underscores. + + ----------------------- + -- Target Parameters -- + ----------------------- + -- The following parameters correspond to the variables defined in the -- private part of System (without the terminating _On_Target). Note -- that it is required that all parameters defined here be specified @@ -52,7 +158,18 @@ package Targparm is -- All these parameters should be regarded as read only by all clients -- of the package. The only way they get modified is by calling the - -- Get_Target_Parameters routine which reads the values from System. + -- Get_Target_Parameters routine which reads the values from a provided + -- text buffer containing the source of the system package. + + ---------------------------- + -- Special Target Control -- + ---------------------------- + + -- The great majority of GNAT ports are based on GCC. The switches in + -- This section indicate the use of some non-standard target back end. + + AAMP_On_Target : Boolean; + -- Set to True if target is AAMP. ------------------------------- -- Backend Arithmetic Checks -- @@ -78,9 +195,9 @@ package Targparm is -- Control of Exception Handling -- ----------------------------------- - -- GNAT provides two methods of implementing exceptions: + -- GNAT implements three methods of implementing exceptions: - -- Longjmp/Setjmp (-gnatL) + -- Front-End Longjmp/Setjmp Exceptions -- This approach uses longjmp/setjmp to handle exceptions. It -- uses less storage, and can often propagate exceptions faster, @@ -88,7 +205,14 @@ package Targparm is -- up an exception handler. This approach is available on all -- targets, and is the default where it is the only approach. - -- Zero Cost (-gnatZ) + -- The generation of the setjmp and longjmp calls is handled by + -- the front end of the compiler (this includes gigi in the case + -- of the standard GCC back end). It does not use any back end + -- suport (such as the GCC3 exception handling mechanism). When + -- this approach is used, the compiler generates special exception + -- handlers for handling cleanups when an exception is raised. + + -- Front-End Zero Cost Exceptions -- This approach uses separate exception tables. These use extra -- storage, and exception propagation can be quite slow, but there @@ -97,28 +221,193 @@ package Targparm is -- is only available on some targets, and is the default where it is -- available. + -- The generation of the exception tables is handled by the front + -- end of the compiler. It does not use any back end support (such + -- as the GCC3 exception handling mechanism). When this approach + -- is used, the compiler generates special exception handlers for + -- handling cleanups when an exception is raised. + + -- Back-End Zero Cost Exceptions + + -- With this approach, the back end handles the generation and + -- handling of exceptions. For example, the GCC3 exception handling + -- mechanisms are used in this mode. The front end simply generates + -- code for explicit exception handlers, and AT END cleanup handlers + -- are simply passed unchanged to the backend for generating cleanups + -- both in the exceptional and non-exceptional cases. + + -- As the name implies, this approach generally uses a zero-cost + -- mechanism with tables, but the tables are generated by the back + -- end. However, since the back-end is entirely responsible for the + -- handling of exceptions, another mechanism might be used. In the + -- case of GCC3 for instance, it might be the case that the compiler + -- is configured for setjmp/longjmp handling, then everything will + -- work correctly. However, it is definitely preferred that the + -- back end provide zero cost exception handling. + + -- Controlling the selection of methods + + -- The Front-End Longjmp/Setjmp approach is always available in + -- all implementations. If it is not the default method, then it + -- may be explicitly specified by the use of -gnatL. Note however + -- that there is a requirement that all Ada units in a partition + -- be compiled with this overriding option if it is not the default. + + -- On some, but not all, implementations of GNAT, one of the two + -- ZCX approaches (but not both) is implemented. If this is the + -- case, and ZCX is not the default mechanism, then ZCX handling + -- (front-end or back-end according to the implementation) may be + -- specified by use of the -gnatZ switch. Again, this switch must + -- be used to compile all Ada units in a partition. The use of + -- the -gnatZ switch will cause termination with a fatal error. + + -- Finally the debug option -gnatdX can be used to force the + -- compiler to operate in front-end ZCX exception mode and force + -- the front end to generate exception tables. This is only useful + -- for debugging purposes for implementations which do not provide + -- the possibility of front-end ZCX mode. The resulting object file + -- is unusable, but this debug switch may still be useful (e.g. in + -- conjunction with -gnatG) for front-end debugging purposes. + + -- Control of Available Methods and Defaults + + -- The following switches specify which of the two ZCX methods + -- (if any) is available in an implementation, and which method + -- is the default method. + ZCX_By_Default_On_Target : Boolean; - -- Indicates if zero cost exceptions are active by default. + -- Indicates if zero cost exceptions are active by default. If this + -- variable is False, then the only possible exception method is the + -- front-end setjmp/longjmp approach, and this is the default. If + -- this variable is True, then one of the following two flags must + -- be True, and represents the method to be used by default. GCC_ZCX_Support_On_Target : Boolean; - -- Indicates that when ZCX is active the mechanism to be used is the - -- standard GCC ZCX mechanism (introduced in GCC 3.1) + -- Indicates that when ZCX is active, the mechanism to be used is the + -- back-end ZCX exception approach. If this variable is set to True, + -- then Front_End_ZCX_Support_On_Target must be False. Front_End_ZCX_Support_On_Target : Boolean; - -- Indicates that when ZCX is active (and GCC_ZCX_Support is not set) - -- the mechanism to be used is the GNAT front end specific ZCX mechanism - - --------------------------------------- - -- High_Integrity (No Run Time) Mode -- - --------------------------------------- - - -- In High_Integrity mode, there is no system run-time, and the flag - -- Opt.No_Run_Time is set so that the language is appropriately - -- restricted to forbid construct that would generate run-time calls. - - High_Integrity_Mode_On_Target : Boolean; - -- Indicates that this build is for a high integrity mode version of - -- GNAT, so that no run time is permitted. + -- Indicates that when ZCX is active, the mechanism to be used is the + -- front-end ZCX exception approach. If this variable is set to True, + -- then GCC_ZCX_Support_On_Target must be False. + + -------------------------------- + -- Configurable Run-Time Mode -- + -------------------------------- + + -- In configurable run-time mode, the system run-time may not support + -- the full Ada language. The effect of setting this switch is to let + -- the compiler know that it is not surprising (i.e. the system is not + -- misconfigured) if run-time library units or entities within units are + -- not present in the run-time. + + Configurable_Run_Time_On_Target : Boolean; + -- Indicates that the system.ads file is for a configurable run-time + -- + -- This has some specific effects as follows + -- + -- The binder generates the gnat_argc/argv/envp variables in the + -- binder file instead of being imported from the run-time library. + -- If Command_Line_Args_On_Target is set to False, then the + -- generation of these variables is suppressed completely. + -- + -- The binder generates the gnat_exit_status variable in the binder + -- file instead of being imported from the run-time library. If + -- Exit_Status_Supported_On_Target is set to False, then the + -- generation of this variable is suppressed entirely. + -- + -- The routine __gnat_break_start is defined within the binder file + -- instead of being imported from the run-time library. + -- + -- The variable __gnat_exit_status is generated within the binder file + -- instead of being imported from the run-time library. + -- + -- No -Ldir switches are added for the linker step + -- + -- No standard switches are added after user file entries to the + -- linker line. All such switches must be explicit. In other words + -- the option -nostdlib is implicit with a configurable run-time. + + Suppress_Standard_Library_On_Target : Boolean; + -- If this flag is True, then the standard library is not included by + -- default in the executable (see unit System.Standard_Library in file + -- s-stalib.ads for details of what this includes). This is for example + -- set True for the zero foot print case, where these files should not + -- be included by default. + -- + -- This flag has some other related effects: + -- + -- The generation of global variables in the bind file is suppressed, + -- with the exception of the priority of the environment task, which + -- is needed by the Ravenscar run-time. + -- + -- The generation of exception tables is suppressed for front end + -- ZCX exception handling (since we assume no exception handling). + -- + -- The calls to __gnat_initialize and __gnat_finalize are omitted + -- + -- All finalization and initialization (controlled types) is omitted + -- + -- The routine __gnat_handler_installed is not imported + + --------------------- + -- Duration Format -- + --------------------- + + -- By default, type Duration is a 64-bit fixed-point type with a delta + -- and small of 10**(-9) (i.e. it is a count in nanoseconds. This flag + -- allows that standard format to be modified. + + Duration_32_Bits_On_Target : Boolean; + -- If True, then Duration is represented in 32 bits and the delta and + -- small values are set to 20.0*(10**(-3)) (i.e. it is a count in units + -- of 20 milliseconds. + + ------------------------------------ + -- Back-End Code Generation Flags -- + ------------------------------------ + + -- These flags indicate possible limitations in what the code generator + -- can handle. They will all be True for a full run-time, but one or more + -- of these may be false for a configurable run-time, and if a feature is + -- used at the source level, and the corresponding flag is false, then an + -- error message will be issued saying the feature is not supported. + + Support_64_Bit_Divides_On_Target : Boolean; + -- If True, the back end supports 64-bit divide operations. If False, then + -- the source program may not contain 64-bit divide operations. This is + -- specifically useful in the zero foot-print case, where the issue is + -- whether there is a hardware divide instruction for 64-bits so that + -- no run-time support is required. It should always be set True if the + -- necessary run-time support is present. + + Support_Aggregates_On_Target : Boolean; + -- In the general case, the use of aggregates may generate calls + -- to run-time routines in the C library, including memset, memcpy, + -- memmove, and bcopy. This flag is set to True if these routines + -- are available. If any of these routines is not available, then + -- this flag is False, and the use of aggregates is not permitted. + + Support_Composite_Assign_On_Target : Boolean; + -- The assignment of composite objects other than small records and + -- arrays whose size is 64-bits or less and is set by an explicit + -- size clause may generate calls to memcpy, memmove, and bcopy. + -- If versions of all these routines are available, then this flag + -- is set to True. If any of these routines is not available, then + -- the flag is set False, and composite assignments are not allowed. + + Support_Composite_Compare_On_Target : Boolean; + -- If this flag is True, then the back end supports bit-wise comparison + -- of composite objects for equality, either generating inline code or + -- calling appropriate (and available) run-time routines. If this flag + -- is False, then the back end does not provide this support, and the + -- front end uses component by component comparison for composites. + + Support_Long_Shifts_On_Target : Boolean; + -- If True, the back end supports 64-bit shift operations. If False, then + -- the source program may not contain explicit 64-bit shifts. In addition, + -- the code generated for packed arrays will avoid the use of long shifts. ------------------------------- -- Control of Stack Checking -- @@ -164,13 +453,23 @@ package Targparm is -- For most ports of GNAT, command line arguments are supported. The -- following flag is set to False for targets that do not support - -- command line arguments (notably VxWorks). + -- command line arguments (VxWorks and AAMP). Note that support of + -- command line arguments is not required on such targets (RM A.15(13)). Command_Line_Args_On_Target : Boolean; - -- Set False if no command line arguments on target + -- Set False if no command line arguments on target. Note that if this + -- is False in with Configurable_Run_Time_On_Target set to True, then + -- this causes suppression of generation of the argv/argc variables + -- used to record command line arguments. + + -- Similarly, most ports support the use of an exit status, but AAMP + -- is an exception (as allowed by RM A.15(18-20)) - -- Note: this is prepared for future use, but not yet used, since we - -- do not yet have a way of propagating Targparm params to the binder + Exit_Status_Supported_On_Target : Boolean; + -- Set False if returning of an exit status is not supported on target. + -- Note that if this False in with Configurable_Run_Time_On_Target + -- set to True, then this causes suppression of the gnat_exit_status + -- variable used to recod the exit status. ----------------------- -- Main Program Name -- @@ -186,28 +485,6 @@ package Targparm is Use_Ada_Main_Program_Name_On_Target : Boolean; -- Set True to use the Ada main program name as the main name - -- Note: this is prepared for future use, but not yet used, since we - -- do not yet have a way of propagating Targparm params to the binder - - ---------------------------- - -- Support of Long Shifts -- - ---------------------------- - - -- In GNORT mode, we cannot call library routines, and in particular - -- we cannot call routines for long (64-bit) shifts if such routines - -- are required on the target. This comes up in the context of support - -- of packed arrays. We can only represent packed arrays whose length - -- is in the range 33- to 64-bits as modular types if long shifts are - -- done with inline code. - - -- For the default version, for now we set long shifts inlined as True - -- This may not be quite accurate, but until we get proper separate - -- System's for each target, it is a safer choice. - - Long_Shifts_Inlined_On_Target : Boolean; - -- Indicates if long (double word) shifts are generated using inlined - -- code (and thus are permissible in No_Run_Time mode). - ---------------------------------------------- -- Boolean-Valued Floating-Point Attributes -- ---------------------------------------------- @@ -226,9 +503,6 @@ package Targparm is -- the partition. We probably should add such consistency checks in future, -- but for now we don't do this. - AAMP_On_Target : Boolean; - -- Set to True if target is AAMP. - Denorm_On_Target : Boolean; -- Set to False on targets that do not reliably support denormals. -- Reliably here means for all settings of the relevant -m flag, so @@ -313,8 +587,23 @@ package Targparm is -- Subprograms -- ----------------- + -- These subprograms are used to initialize the target parameter values + -- from the system.ads file. Note that this is only done once, so if more + -- than one call is made to either routine, the second and subsequent + -- calls are ignored. + + procedure Get_Target_Parameters + (System_Text : Source_Buffer_Ptr; + Source_First : Source_Ptr; + Source_Last : Source_Ptr); + -- Called at the start of execution to obtain target parameters from + -- the source of package System. The parameters provide the source + -- text to be scanned (in System_Text (Source_First .. Source_Last)). + procedure Get_Target_Parameters; - -- Called at the start of execution to read the source of System and - -- obtain and set the values of the above parameters. + -- This version reads in system.ads using Osint. The idea is that the + -- caller uses the first version if they have to read system.ads anyway + -- (e.g. the compiler) and uses this simpler interface if system.ads is + -- not otherwise needed. end Targparm; |