* arm.c (FL_WBUF): Define.
[official-gcc.git] / gcc / ada / targparm.ads
blob48b05ab5353f0acdef4764d97dd8882e9563bdc0
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT RUN-TIME COMPONENTS --
4 -- --
5 -- T A R G P A R M --
6 -- --
7 -- S p e c --
8 -- --
9 -- Copyright (C) 1999-2005 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 2, 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. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING. If not, write --
19 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
20 -- MA 02111-1307, USA. --
21 -- --
22 -- GNAT was originally developed by the GNAT team at New York University. --
23 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 -- --
25 ------------------------------------------------------------------------------
27 -- This package obtains parameters from the target runtime version of
28 -- System, to indicate parameters relevant to the target environment.
30 -- Conceptually, these parameters could be obtained using rtsfind, but
31 -- we do not do this for four reasons:
33 -- 1. Compiling System for every compilation wastes time
35 -- 2. This compilation impedes debugging by adding extra compile steps
37 -- 3. There are recursion problems coming from compiling System itself
38 -- or any of its children.
40 -- 4. The binder also needs the parameters, and we do not want to have
41 -- to drag a lot of front end stuff into the binder.
43 -- For all these reasons, we read in the source of System, and then scan
44 -- it at the text level to extract the parameter values.
46 -- Note however, that later on, when the ali file is written, we make sure
47 -- that the System file is at least parsed, so that the checksum is properly
48 -- computed and set in the ali file. This partially negates points 1 and 2
49 -- above although just parsing is quick and does not impact debugging much.
51 -- The parameters acquired by this routine from system.ads fall into four
52 -- categories:
54 -- 1. Configuration pragmas, that must appear at the start of the file.
55 -- Any such pragmas automatically apply to any unit compiled in the
56 -- presence of this system file. Only a limited set of such pragmas
57 -- may appear as documented in the corresponding section below,
59 -- 2. Target parameters. These are boolean constants that are defined
60 -- in the private part of the package giving fixed information
61 -- about the target architecture, and the capabilities of the
62 -- code generator and run-time library.
64 -- 3. Identification information. This is an optional string constant
65 -- that gives the name of the run-time library configuration. This
66 -- line may be ommitted for a version of system.ads to be used with
67 -- the full Ada 95 run time.
69 -- 4. Other characterisitics of package System. At the current time the
70 -- only item in this category is whether type Address is private.
72 with Rident; use Rident;
73 with Types; use Types;
75 package Targparm is
77 ---------------------------
78 -- Configuration Pragmas --
79 ---------------------------
81 -- The following switches get set if the corresponding configuration
82 -- pragma is scanned from the source of system.ads. No other pragmas
83 -- are permitted to appear at the start of the system.ads source file.
85 -- If a pragma Discard_Names appears, then Opt.Global_Discard_Names is
86 -- set to True to indicate that all units must be compiled in this mode.
88 -- If a pragma Locking_Policy appears, then Opt.Locking_Policy is set
89 -- to the first character of the policy name, and Opt.Locking_Policy_Sloc
90 -- is set to System_Location.
92 -- If a pragma Normalize_Scalars appears, then Opt.Normalize_Scalars
93 -- is set True, as well as Opt.Init_Or_Norm_Scalars.
95 -- If a pragma Queuing_Policy appears, then Opt.Queuing_Policy is set
96 -- to the first character of the policy name, and Opt.Queuing_Policy_Sloc
97 -- is set to System_Location.
99 -- If a pragma Task_Dispatching_Policy appears, then the flag
100 -- Opt.Task_Dispatching_Policy is set to the first character of the
101 -- policy name, and Opt.Task_Dispatching_Policy_Sloc is set to
102 -- System_Location.
104 -- If a pragma Polling (On) appears, then the flag Opt.Polling_Required
105 -- is set to True.
107 -- If a pragma Detect_Blocking appears, then the flag Opt.Detect_Blocking
108 -- is set to True.
110 -- if a pragma Suppress_Exception_Locations appears, then the flag
111 -- Opt.Exception_Locations_Suppressed is set to True.
113 -- If a pragma Profile with a valid profile argument appears, then
114 -- the appropriate restrictions and policy flags are set.
116 -- The only other pragma allowed is a pragma Restrictions that specifies
117 -- a restriction that will be imposed on all units in the partition. Note
118 -- that in this context, only one restriction can be specified in a single
119 -- pragma, and the pragma must appear on its own on a single source line.
121 -- If package System contains exactly the line "type Address is private;"
122 -- then the flag Opt.Address_Is_Private is set True, otherwise this flag
123 -- is set False.
125 Restrictions_On_Target : Restrictions_Info;
126 -- Records restrictions specified by system.ads. Only the Set and Value
127 -- members are modified. The Violated and Count fields are never modified.
128 -- Note that entries can be set either by a pragma Restrictions or by
129 -- a pragma Profile.
131 -------------------
132 -- Run Time Name --
133 -------------------
135 -- This parameter should be regarded as read only by all clients of
136 -- of package. The only way they get modified is by calling the
137 -- Get_Target_Parameters routine which reads the values from a provided
138 -- text buffer containing the source of the system package.
140 -- The corresponding string constant is placed immediately at the start
141 -- of the private part of system.ads if is present, e.g. in the form:
143 -- Run_Time_Name : constant String := "Zero Footprint Run Time";
145 -- the corresponding messages will look something like
147 -- xxx not supported (Zero Footprint Run Time)
149 Run_Time_Name_On_Target : Name_Id := No_Name;
150 -- Set to appropriate names table entry Id value if a Run_Time_Name
151 -- string constant is defined in system.ads. This name is used only
152 -- for the configurable run-time case, and is used to parametrize
153 -- messages that complain about non-supported run-time features.
154 -- The name should contain only letters A-Z, digits 1-9, spaces,
155 -- and underscores.
157 -----------------------
158 -- Target Parameters --
159 -----------------------
161 -- The following parameters correspond to the variables defined in the
162 -- private part of System (without the terminating _On_Target). Note
163 -- that it is required that all parameters defined here be specified
164 -- in the target specific version of system.ads (there are no defaults).
166 -- All these parameters should be regarded as read only by all clients
167 -- of the package. The only way they get modified is by calling the
168 -- Get_Target_Parameters routine which reads the values from a provided
169 -- text buffer containing the source of the system package.
171 -- The default values here are used if no value is found in system.ads.
172 -- This should normally happen only if the special version of system.ads
173 -- used by the compiler itself is in use. The default values are suitable
174 -- for use by the compiler itself in normal environments. This approach
175 -- allows the possibility of new versions of the compiler (possibly with
176 -- new system parameters added) being used to compile older versions of
177 -- the compiler sources. This is not guaranteed to work, but often will
178 -- and by setting appropriate default values, we make it more likely that
179 -- this can succeed.
181 Compiler_System_Version : Boolean := True;
182 -- This is set False in all target dependent versions of System. In the
183 -- compiler default version, it is omitted entirely, meaning that the
184 -- above default value of True will be set. If the flag is False, then
185 -- the scanning circuits in the body of this package do an error check to
186 -- ensure that all parameters other than this one are specified and not
187 -- defaulted. If the parameter is set True, then this check is omitted,
188 -- and any parameters not present in system.ads are left set to their
189 -- default value as described above.
191 ----------------------------
192 -- Special Target Control --
193 ----------------------------
195 -- The great majority of GNAT ports are based on GCC. The switches in
196 -- This section indicate the use of some non-standard target back end
197 -- or other special targetting requirements.
199 AAMP_On_Target : Boolean := False;
200 -- Set to True if target is AAMP
202 OpenVMS_On_Target : Boolean := False;
203 -- Set to True if target is OpenVMS
205 -------------------------------
206 -- Backend Arithmetic Checks --
207 -------------------------------
209 -- Divide and overflow checks are either done in the front end or
210 -- back end. The front end will generate checks when required unless
211 -- the corresponding parameter here is set to indicate that the back
212 -- end will generate the required checks (or that the checks are
213 -- automatically performed by the hardware in an appropriate form).
215 Backend_Divide_Checks_On_Target : Boolean := False;
216 -- Set True if the back end generates divide checks, or if the hardware
217 -- checks automatically. Set False if the front end must generate the
218 -- required tests using explicit expanded code.
220 Backend_Overflow_Checks_On_Target : Boolean := False;
221 -- Set True if the back end generates arithmetic overflow checks, or if
222 -- the hardware checks automatically. Set False if the front end must
223 -- generate the required tests using explicit expanded code.
225 -----------------------------------
226 -- Control of Exception Handling --
227 -----------------------------------
229 -- GNAT implements three methods of implementing exceptions:
231 -- Front-End Longjmp/Setjmp Exceptions
233 -- This approach uses longjmp/setjmp to handle exceptions. It
234 -- uses less storage, and can often propagate exceptions faster,
235 -- at the expense of (sometimes considerable) overhead in setting
236 -- up an exception handler. This approach is available on all
237 -- targets, and is the default where it is the only approach.
239 -- The generation of the setjmp and longjmp calls is handled by
240 -- the front end of the compiler (this includes gigi in the case
241 -- of the standard GCC back end). It does not use any back end
242 -- suport (such as the GCC3 exception handling mechanism). When
243 -- this approach is used, the compiler generates special exception
244 -- handlers for handling cleanups when an exception is raised.
246 -- Front-End Zero Cost Exceptions
248 -- This approach uses separate exception tables. These use extra
249 -- storage, and exception propagation can be quite slow, but there
250 -- is no overhead in setting up an exception handler (it is to this
251 -- latter operation that the phrase zero-cost refers). This approach
252 -- is only available on some targets, and is the default where it is
253 -- available.
255 -- The generation of the exception tables is handled by the front
256 -- end of the compiler. It does not use any back end support (such
257 -- as the GCC3 exception handling mechanism). When this approach
258 -- is used, the compiler generates special exception handlers for
259 -- handling cleanups when an exception is raised.
261 -- Back-End Zero Cost Exceptions
263 -- With this approach, the back end handles the generation and
264 -- handling of exceptions. For example, the GCC3 exception handling
265 -- mechanisms are used in this mode. The front end simply generates
266 -- code for explicit exception handlers, and AT END cleanup handlers
267 -- are simply passed unchanged to the backend for generating cleanups
268 -- both in the exceptional and non-exceptional cases.
270 -- As the name implies, this approach generally uses a zero-cost
271 -- mechanism with tables, but the tables are generated by the back
272 -- end. However, since the back-end is entirely responsible for the
273 -- handling of exceptions, another mechanism might be used. In the
274 -- case of GCC3 for instance, it might be the case that the compiler
275 -- is configured for setjmp/longjmp handling, then everything will
276 -- work correctly. However, it is definitely preferred that the
277 -- back end provide zero cost exception handling.
279 -- Controlling the selection of methods
281 -- The Front-End Longjmp/Setjmp approach is always available in
282 -- all implementations. If it is not the default method, then it
283 -- may be explicitly specified by the use of -gnatL. Note however
284 -- that there is a requirement that all Ada units in a partition
285 -- be compiled with this overriding option if it is not the default.
287 -- On some, but not all, implementations of GNAT, one of the two
288 -- ZCX approaches (but not both) is implemented. If this is the
289 -- case, and ZCX is not the default mechanism, then ZCX handling
290 -- (front-end or back-end according to the implementation) may be
291 -- specified by use of the -gnatZ switch. Again, this switch must
292 -- be used to compile all Ada units in a partition. The use of
293 -- the -gnatZ switch will cause termination with a fatal error.
295 -- Finally the debug option -gnatdX can be used to force the
296 -- compiler to operate in front-end ZCX exception mode and force
297 -- the front end to generate exception tables. This is only useful
298 -- for debugging purposes for implementations which do not provide
299 -- the possibility of front-end ZCX mode. The resulting object file
300 -- is unusable, but this debug switch may still be useful (e.g. in
301 -- conjunction with -gnatG) for front-end debugging purposes.
303 -- Control of Available Methods and Defaults
305 -- The following switches specify which of the two ZCX methods
306 -- (if any) is available in an implementation, and which method
307 -- is the default method.
309 ZCX_By_Default_On_Target : Boolean := False;
310 -- Indicates if zero cost exceptions are active by default. If this
311 -- variable is False, then the only possible exception method is the
312 -- front-end setjmp/longjmp approach, and this is the default. If
313 -- this variable is True, then one of the following two flags must
314 -- be True, and represents the method to be used by default.
316 GCC_ZCX_Support_On_Target : Boolean := False;
317 -- Indicates that when ZCX is active, the mechanism to be used is the
318 -- back-end ZCX exception approach. If this variable is set to True,
319 -- then Front_End_ZCX_Support_On_Target must be False.
321 Front_End_ZCX_Support_On_Target : Boolean := False;
322 -- Indicates that when ZCX is active, the mechanism to be used is the
323 -- front-end ZCX exception approach. If this variable is set to True,
324 -- then GCC_ZCX_Support_On_Target must be False.
326 ------------------------------------
327 -- Run-Time Library Configuration --
328 ------------------------------------
330 -- In configurable run-time mode, the system run-time may not support
331 -- the full Ada language. The effect of setting this switch is to let
332 -- the compiler know that it is not surprising (i.e. the system is not
333 -- misconfigured) if run-time library units or entities within units are
334 -- not present in the run-time.
336 Configurable_Run_Time_On_Target : Boolean := False;
337 -- Indicates that the system.ads file is for a configurable run-time
339 -- This has some specific effects as follows
341 -- The binder generates the gnat_argc/argv/envp variables in the
342 -- binder file instead of being imported from the run-time library.
343 -- If Command_Line_Args_On_Target is set to False, then the
344 -- generation of these variables is suppressed completely.
346 -- The binder generates the gnat_exit_status variable in the binder
347 -- file instead of being imported from the run-time library. If
348 -- Exit_Status_Supported_On_Target is set to False, then the
349 -- generation of this variable is suppressed entirely.
351 -- The routine __gnat_break_start is defined within the binder file
352 -- instead of being imported from the run-time library.
354 -- The variable __gnat_exit_status is generated within the binder file
355 -- instead of being imported from the run-time library.
357 Suppress_Standard_Library_On_Target : Boolean := False;
358 -- If this flag is True, then the standard library is not included by
359 -- default in the executable (see unit System.Standard_Library in file
360 -- s-stalib.ads for details of what this includes). This is for example
361 -- set True for the zero foot print case, where these files should not
362 -- be included by default.
364 -- This flag has some other related effects:
366 -- The generation of global variables in the bind file is suppressed,
367 -- with the exception of the priority of the environment task, which
368 -- is needed by the Ravenscar run-time.
370 -- The generation of exception tables is suppressed for front end
371 -- ZCX exception handling (since we assume no exception handling).
373 -- The calls to __gnat_initialize and __gnat_finalize are omitted
375 -- All finalization and initialization (controlled types) is omitted
377 -- The routine __gnat_handler_installed is not imported
379 Preallocated_Stacks_On_Target : Boolean := False;
380 -- If this flag is True, then the expander preallocates all task stacks
381 -- at compile time. If the flag is False, then task stacks are not pre-
382 -- allocated, and task stack allocation is the responsibility of the
383 -- run-time (which typically delegates the task to the underlying
384 -- operating system environment).
386 ---------------------
387 -- Duration Format --
388 ---------------------
390 -- By default, type Duration is a 64-bit fixed-point type with a delta
391 -- and small of 10**(-9) (i.e. it is a count in nanoseconds. This flag
392 -- allows that standard format to be modified.
394 Duration_32_Bits_On_Target : Boolean := False;
395 -- If True, then Duration is represented in 32 bits and the delta and
396 -- small values are set to 20.0*(10**(-3)) (i.e. it is a count in units
397 -- of 20 milliseconds.
399 ------------------------------------
400 -- Back-End Code Generation Flags --
401 ------------------------------------
403 -- These flags indicate possible limitations in what the code generator
404 -- can handle. They will all be True for a full run-time, but one or more
405 -- of these may be false for a configurable run-time, and if a feature is
406 -- used at the source level, and the corresponding flag is false, then an
407 -- error message will be issued saying the feature is not supported.
409 Support_64_Bit_Divides_On_Target : Boolean := True;
410 -- If True, the back end supports 64-bit divide operations. If False, then
411 -- the source program may not contain 64-bit divide operations. This is
412 -- specifically useful in the zero foot-print case, where the issue is
413 -- whether there is a hardware divide instruction for 64-bits so that
414 -- no run-time support is required. It should always be set True if the
415 -- necessary run-time support is present.
417 Support_Aggregates_On_Target : Boolean := True;
418 -- In the general case, the use of aggregates may generate calls
419 -- to run-time routines in the C library, including memset, memcpy,
420 -- memmove, and bcopy. This flag is set to True if these routines
421 -- are available. If any of these routines is not available, then
422 -- this flag is False, and the use of aggregates is not permitted.
424 Support_Composite_Assign_On_Target : Boolean := True;
425 -- The assignment of composite objects other than small records and
426 -- arrays whose size is 64-bits or less and is set by an explicit
427 -- size clause may generate calls to memcpy, memmove, and bcopy.
428 -- If versions of all these routines are available, then this flag
429 -- is set to True. If any of these routines is not available, then
430 -- the flag is set False, and composite assignments are not allowed.
432 Support_Composite_Compare_On_Target : Boolean := True;
433 -- If this flag is True, then the back end supports bit-wise comparison
434 -- of composite objects for equality, either generating inline code or
435 -- calling appropriate (and available) run-time routines. If this flag
436 -- is False, then the back end does not provide this support, and the
437 -- front end uses component by component comparison for composites.
439 Support_Long_Shifts_On_Target : Boolean := True;
440 -- If True, the back end supports 64-bit shift operations. If False, then
441 -- the source program may not contain explicit 64-bit shifts. In addition,
442 -- the code generated for packed arrays will avoid the use of long shifts.
444 -------------------------------
445 -- Control of Stack Checking --
446 -------------------------------
448 -- GNAT provides two methods of implementing exceptions:
450 -- GCC Probing Mechanism
452 -- This approach uses the standard GCC mechanism for
453 -- stack checking. The method assumes that accessing
454 -- storage immediately beyond the end of the stack
455 -- will result in a trap that is converted to a storage
456 -- error by the runtime system. This mechanism has
457 -- minimal overhead, but requires complex hardware,
458 -- operating system and run-time support. Probing is
459 -- the default method where it is available. The stack
460 -- size for the environment task depends on the operating
461 -- system and cannot be set in a system-independent way.
463 -- GNAT Stack-limit Checking
465 -- This method relies on comparing the stack pointer
466 -- with per-task stack limits. If the check fails, an
467 -- exception is explicitly raised. The advantage is
468 -- that the method requires no extra system dependent
469 -- runtime support and can be used on systems without
470 -- memory protection as well, but at the cost of more
471 -- overhead for doing the check. This method is the
472 -- default on systems that lack complete support for
473 -- probing.
475 Stack_Check_Probes_On_Target : Boolean := False;
476 -- Indicates if stack check probes are used, as opposed to the standard
477 -- target independent comparison method.
479 Stack_Check_Default_On_Target : Boolean := False;
480 -- Indicates if stack checking is on by default
482 ----------------------------
483 -- Command Line Arguments --
484 ----------------------------
486 -- For most ports of GNAT, command line arguments are supported. The
487 -- following flag is set to False for targets that do not support
488 -- command line arguments (VxWorks and AAMP). Note that support of
489 -- command line arguments is not required on such targets (RM A.15(13)).
491 Command_Line_Args_On_Target : Boolean := True;
492 -- Set False if no command line arguments on target. Note that if this
493 -- is False in with Configurable_Run_Time_On_Target set to True, then
494 -- this causes suppression of generation of the argv/argc variables
495 -- used to record command line arguments.
497 -- Similarly, most ports support the use of an exit status, but AAMP
498 -- is an exception (as allowed by RM A.15(18-20))
500 Exit_Status_Supported_On_Target : Boolean := True;
501 -- Set False if returning of an exit status is not supported on target.
502 -- Note that if this False in with Configurable_Run_Time_On_Target
503 -- set to True, then this causes suppression of the gnat_exit_status
504 -- variable used to record the exit status.
506 -----------------------
507 -- Main Program Name --
508 -----------------------
510 -- When the binder generates the main program to be used to create the
511 -- executable, the main program name is main by default (to match the
512 -- usual Unix practice). If this parameter is set to True, then the
513 -- name is instead by default taken from the actual Ada main program
514 -- name (just the name of the child if the main program is a child unit).
515 -- In either case, this value can be overridden using -M name.
517 Use_Ada_Main_Program_Name_On_Target : Boolean := False;
518 -- Set True to use the Ada main program name as the main name
520 ----------------------------------------------
521 -- Boolean-Valued Floating-Point Attributes --
522 ----------------------------------------------
524 -- The constants below give the values for representation oriented
525 -- floating-point attributes that are the same for all float types
526 -- on the target. These are all boolean values.
528 -- A value is only True if the target reliably supports the corresponding
529 -- feature. Reliably here means that support is guaranteed for all
530 -- possible settings of the relevant compiler switches (like -mieee),
531 -- since we cannot control the user setting of those switches.
533 -- The attributes cannot dependent on the current setting of compiler
534 -- switches, since the values must be static and consistent throughout
535 -- the partition. We probably should add such consistency checks in future,
536 -- but for now we don't do this.
538 -- Note: the compiler itself does not use floating-point, so the
539 -- settings of the defaults here are not really relevant.
541 -- Note: in some cases, proper support of some of these floating point
542 -- features may require a specific switch (e.g. -mieee on the Alpha)
543 -- to be used to obtain full RM compliant support.
545 Denorm_On_Target : Boolean := False;
546 -- Set to False on targets that do not reliably support denormals
548 Machine_Rounds_On_Target : Boolean := True;
549 -- Set to False for targets where S'Machine_Rounds is False
551 Machine_Overflows_On_Target : Boolean := False;
552 -- Set to True for targets where S'Machine_Overflows is True
554 Signed_Zeros_On_Target : Boolean := True;
555 -- Set to False on targets that do not reliably support signed zeros.
557 -------------------------------------------
558 -- Boolean-Valued Fixed-Point Attributes --
559 -------------------------------------------
561 Fractional_Fixed_Ops_On_Target : Boolean := False;
562 -- Set to True for targets that support fixed-by-fixed multiplication
563 -- and division for fixed-point types with a small value equal to
564 -- 2 ** (-(T'Object_Size - 1)) and whose values have an absolute
565 -- value less than 1.0.
567 --------------------------------------------------------------
568 -- Handling of Unconstrained Values Returned from Functions --
569 --------------------------------------------------------------
571 -- Functions that return variable length objects, notably unconstrained
572 -- arrays are a special case, because there is no simple obvious way of
573 -- implementing this feature. Furthermore, this capability is not present
574 -- in C++ or C, so typically the system ABI does not handle this case.
576 -- GNAT uses two different approaches
578 -- The Secondary Stack
580 -- The secondary stack is a special storage pool that is used for
581 -- this purpose. The called function places the result on the
582 -- secondary stack, and the caller uses or copies the value from
583 -- the secondary stack, and pops the secondary stack after the
584 -- value is consumed. The secondary stack is outside the system
585 -- ABI, and the important point is that although generally it is
586 -- handled in a stack like manner corresponding to the subprogram
587 -- call structure, a return from a function does NOT pop the stack.
589 -- DSP (Depressed Stack Pointer)
591 -- Some targets permit the implementation of a function call/return
592 -- protocol in which the function does not pop the main stack pointer
593 -- on return, but rather returns with the stack pointer depressed.
594 -- This is not generally permitted by any ABI, but for at least some
595 -- targets, the implementation of alloca provides a model for this
596 -- approach. If return-with-DSP is implemented, then functions that
597 -- return variable length objects do it by returning with the stack
598 -- pointer depressed, and the returned object is a pointer to the
599 -- area within the stack frame of the called procedure that contains
600 -- the returned value. The caller must then pop the main stack when
601 -- this value is consumed.
603 Functions_Return_By_DSP_On_Target : Boolean := False;
604 -- Set to True if target permits functions to return with using the
605 -- DSP (depressed stack pointer) approach.
607 -----------------
608 -- Data Layout --
609 -----------------
611 -- Normally when using the GCC backend, Gigi and GCC perform much of the
612 -- data layout using the standard layout capabilities of GCC. If the
613 -- parameter Backend_Layout is set to False, then the front end must
614 -- perform all data layout. For further details see the package Layout.
616 Frontend_Layout_On_Target : Boolean := False;
617 -- Set True if front end does layout
619 -----------------
620 -- Subprograms --
621 -----------------
623 -- These subprograms are used to initialize the target parameter values
624 -- from the system.ads file. Note that this is only done once, so if more
625 -- than one call is made to either routine, the second and subsequent
626 -- calls are ignored.
628 procedure Get_Target_Parameters
629 (System_Text : Source_Buffer_Ptr;
630 Source_First : Source_Ptr;
631 Source_Last : Source_Ptr);
632 -- Called at the start of execution to obtain target parameters from
633 -- the source of package System. The parameters provide the source
634 -- text to be scanned (in System_Text (Source_First .. Source_Last)).
636 procedure Get_Target_Parameters;
637 -- This version reads in system.ads using Osint. The idea is that the
638 -- caller uses the first version if they have to read system.ads anyway
639 -- (e.g. the compiler) and uses this simpler interface if system.ads is
640 -- not otherwise needed.
642 end Targparm;