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) 1999-2013, 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. 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 COPYING3. If not, go to -- 19-- http://www.gnu.org/licenses for a complete copy of the license. -- 20-- -- 21-- GNAT was originally developed by the GNAT team at New York University. -- 22-- Extensive contributions were provided by Ada Core Technologies Inc. -- 23-- -- 24------------------------------------------------------------------------------ 25 26-- This package obtains parameters from the target runtime version of System, 27-- to indicate parameters relevant to the target environment. 28 29-- Conceptually, these parameters could be obtained using rtsfind, but 30-- we do not do this for four reasons: 31 32-- 1. Compiling System for every compilation wastes time 33 34-- 2. This compilation impedes debugging by adding extra compile steps 35 36-- 3. There are recursion problems coming from compiling System itself 37-- or any of its children. 38 39-- 4. The binder also needs the parameters, and we do not want to have 40-- to drag a lot of front end stuff into the binder. 41 42-- For all these reasons, we read in the source of System, and then scan 43-- it at the text level to extract the parameter values. 44 45-- Note however, that later on, when the ali file is written, we make sure 46-- that the System file is at least parsed, so that the checksum is properly 47-- computed and set in the ali file. This partially negates points 1 and 2 48-- above although just parsing is quick and does not impact debugging much. 49 50-- The parameters acquired by this routine from system.ads fall into four 51-- categories: 52 53-- 1. Configuration pragmas, that must appear at the start of the file. 54-- Any such pragmas automatically apply to any unit compiled in the 55-- presence of this system file. Only a limited set of such pragmas 56-- may appear as documented in the corresponding section below, 57 58-- 2. Target parameters. These are boolean constants that are defined 59-- in the private part of the package giving fixed information 60-- about the target architecture, and the capabilities of the 61-- code generator and run-time library. 62 63-- 3. Identification information. This is an optional string constant 64-- that gives the name of the run-time library configuration. This 65-- line may be omitted for a version of system.ads to be used with 66-- the full Ada 95 run time. 67 68-- 4. Other characteristics of package System. At the current time the 69-- only item in this category is whether type Address is private. 70 71with Rident; use Rident; 72with Namet; use Namet; 73with Types; use Types; 74 75package Targparm is 76 77 --------------------------- 78 -- Configuration Pragmas -- 79 --------------------------- 80 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. 84 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. 87 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. 91 92 -- If a pragma Normalize_Scalars appears, then Opt.Normalize_Scalars 93 -- is set True, as well as Opt.Init_Or_Norm_Scalars. 94 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. 98 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. 103 104 -- If a pragma Polling (On) appears, then the flag Opt.Polling_Required 105 -- is set to True. 106 107 -- If a pragma Detect_Blocking appears, then the flag Opt.Detect_Blocking 108 -- is set to True. 109 110 -- if a pragma Suppress_Exception_Locations appears, then the flag 111 -- Opt.Exception_Locations_Suppressed is set to True. 112 113 -- If a pragma Profile with a valid profile argument appears, then 114 -- the appropriate restrictions and policy flags are set. 115 116 -- 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. 120 121 -- 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. 124 125 Restrictions_On_Target : Restrictions_Info := No_Restrictions; 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. 130 131 ------------------- 132 -- Run Time Name -- 133 ------------------- 134 135 -- 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. 139 140 -- 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: 142 143 -- Run_Time_Name : constant String := "Zero Footprint Run Time"; 144 145 -- the corresponding messages will look something like 146 147 -- xxx not supported (Zero Footprint Run Time) 148 149 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 parameterize 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. 156 157 -------------------------- 158 -- Executable Extension -- 159 -------------------------- 160 161 Executable_Extension_On_Target : Name_Id := No_Name; 162 -- Executable extension on the target. This name is useful for setting 163 -- the executable extension in a dynamic way, e.g. depending on the 164 -- run time used, rather than using a configure-time macro as done by 165 -- Get_Target_Executable_Suffix. If not set (No_Name), instead use 166 -- System.OS_Lib.Get_Target_Executable_Suffix. 167 168 ----------------------- 169 -- Target Parameters -- 170 ----------------------- 171 172 -- The following parameters correspond to the variables defined in the 173 -- private part of System (without the terminating _On_Target). Note 174 -- that it is required that all parameters defined here be specified 175 -- in the target specific version of system.ads. Thus, to add a new 176 -- parameter, add it to all system*.ads files. (There is a defaulting 177 -- mechanism, but we don't normally take advantage of it, as explained 178 -- below.) 179 180 -- The default values here are used if no value is found in system.ads. 181 -- This should normally happen if the special version of system.ads used 182 -- by the compiler itself is in use or if the value is only relevant to 183 -- a particular target (e.g. OpenVMS, AAMP). The default values are 184 -- suitable for use in normal environments. This approach allows the 185 -- possibility of new versions of the compiler (possibly with new system 186 -- parameters added) being used to compile older versions of the compiler 187 -- sources, as well as avoiding duplicating values in all system-*.ads 188 -- files for flags that are used on a few platforms only. 189 190 -- All these parameters should be regarded as read only by all clients 191 -- of the package. The only way they get modified is by calling the 192 -- Get_Target_Parameters routine which reads the values from a provided 193 -- text buffer containing the source of the system package. 194 195 ---------------------------- 196 -- Special Target Control -- 197 ---------------------------- 198 199 -- The great majority of GNAT ports are based on GCC. The switches in 200 -- This section indicate the use of some non-standard target back end 201 -- or other special targetting requirements. 202 203 AAMP_On_Target : Boolean := False; 204 -- Set to True if target is AAMP 205 206 OpenVMS_On_Target : Boolean := False; 207 -- Set to True if target is OpenVMS 208 209 RTX_RTSS_Kernel_Module_On_Target : Boolean := False; 210 -- Set to True if target is RTSS module for RTX 211 212 type Virtual_Machine_Kind is (No_VM, JVM_Target, CLI_Target); 213 VM_Target : Virtual_Machine_Kind := No_VM; 214 -- Kind of virtual machine targetted 215 -- No_VM: no virtual machine, default case of a standard processor 216 -- JVM_Target: Java Virtual Machine 217 -- CLI_Target: CLI/.NET Virtual Machine 218 219 ------------------------------- 220 -- Backend Arithmetic Checks -- 221 ------------------------------- 222 223 -- Divide and overflow checks are either done in the front end or 224 -- back end. The front end will generate checks when required unless 225 -- the corresponding parameter here is set to indicate that the back 226 -- end will generate the required checks (or that the checks are 227 -- automatically performed by the hardware in an appropriate form). 228 229 Backend_Divide_Checks_On_Target : Boolean := False; 230 -- Set True if the back end generates divide checks, or if the hardware 231 -- checks automatically. Set False if the front end must generate the 232 -- required tests using explicit expanded code. 233 234 Backend_Overflow_Checks_On_Target : Boolean := False; 235 -- Set True if the back end generates arithmetic overflow checks, or if 236 -- the hardware checks automatically. Set False if the front end must 237 -- generate the required tests using explicit expanded code. 238 239 ----------------------------------- 240 -- Control of Exception Handling -- 241 ----------------------------------- 242 243 -- GNAT implements three methods of implementing exceptions: 244 245 -- Front-End Longjmp/Setjmp Exceptions 246 247 -- This approach uses longjmp/setjmp to handle exceptions. It 248 -- uses less storage, and can often propagate exceptions faster, 249 -- at the expense of (sometimes considerable) overhead in setting 250 -- up an exception handler. This approach is available on all 251 -- targets, and is the default where it is the only approach. 252 253 -- The generation of the setjmp and longjmp calls is handled by 254 -- the front end of the compiler (this includes gigi in the case 255 -- of the standard GCC back end). It does not use any back end 256 -- support (such as the GCC3 exception handling mechanism). When 257 -- this approach is used, the compiler generates special exception 258 -- handlers for handling cleanups when an exception is raised. 259 260 -- Front-End Zero Cost Exceptions 261 262 -- This approach uses separate exception tables. These use extra 263 -- storage, and exception propagation can be quite slow, but there 264 -- is no overhead in setting up an exception handler (it is to this 265 -- latter operation that the phrase zero-cost refers). This approach 266 -- is only available on some targets, and is the default where it is 267 -- available. 268 269 -- The generation of the exception tables is handled by the front 270 -- end of the compiler. It does not use any back end support (such 271 -- as the GCC3 exception handling mechanism). When this approach 272 -- is used, the compiler generates special exception handlers for 273 -- handling cleanups when an exception is raised. 274 275 -- Back-End Zero Cost Exceptions 276 277 -- With this approach, the back end handles the generation and 278 -- handling of exceptions. For example, the GCC3 exception handling 279 -- mechanisms are used in this mode. The front end simply generates 280 -- code for explicit exception handlers, and AT END cleanup handlers 281 -- are simply passed unchanged to the backend for generating cleanups 282 -- both in the exceptional and non-exceptional cases. 283 284 -- As the name implies, this approach generally uses a zero-cost 285 -- mechanism with tables, but the tables are generated by the back 286 -- end. However, since the back-end is entirely responsible for the 287 -- handling of exceptions, another mechanism might be used. In the 288 -- case of GCC3 for instance, it might be the case that the compiler 289 -- is configured for setjmp/longjmp handling, then everything will 290 -- work correctly. However, it is definitely preferred that the 291 -- back end provide zero cost exception handling. 292 293 -- Controlling the selection of methods 294 295 -- On most implementations, back-end zero-cost exceptions are used. 296 -- Otherwise, Front-End Longjmp/Setjmp approach is used. 297 -- Note that there is a requirement that all Ada units in a partition 298 -- be compiled with the same exception model. 299 300 -- Control of Available Methods and Defaults 301 302 -- The following switches specify whether ZCX is available, and 303 -- whether it is enabled by default. 304 305 ZCX_By_Default_On_Target : Boolean := False; 306 -- Indicates if zero cost exceptions are active by default. If this 307 -- variable is False, then the only possible exception method is the 308 -- front-end setjmp/longjmp approach, and this is the default. If 309 -- this variable is True, then GCC ZCX is used. 310 311 ------------------------------------ 312 -- Run-Time Library Configuration -- 313 ------------------------------------ 314 315 -- In configurable run-time mode, the system run-time may not support 316 -- the full Ada language. The effect of setting this switch is to let 317 -- the compiler know that it is not surprising (i.e. the system is not 318 -- misconfigured) if run-time library units or entities within units are 319 -- not present in the run-time. 320 321 Configurable_Run_Time_On_Target : Boolean := False; 322 -- Indicates that the system.ads file is for a configurable run-time 323 -- 324 -- This has some specific effects as follows 325 -- 326 -- The binder generates the gnat_argc/argv/envp variables in the 327 -- binder file instead of being imported from the run-time library. 328 -- If Command_Line_Args_On_Target is set to False, then the 329 -- generation of these variables is suppressed completely. 330 -- 331 -- The binder generates the gnat_exit_status variable in the binder 332 -- file instead of being imported from the run-time library. If 333 -- Exit_Status_Supported_On_Target is set to False, then the 334 -- generation of this variable is suppressed entirely. 335 -- 336 -- The routine __gnat_break_start is defined within the binder file 337 -- instead of being imported from the run-time library. 338 -- 339 -- The variable __gnat_exit_status is generated within the binder file 340 -- instead of being imported from the run-time library. 341 342 Suppress_Standard_Library_On_Target : Boolean := False; 343 -- If this flag is True, then the standard library is not included by 344 -- default in the executable (see unit System.Standard_Library in file 345 -- s-stalib.ads for details of what this includes). This is for example 346 -- set True for the zero foot print case, where these files should not 347 -- be included by default. 348 -- 349 -- This flag has some other related effects: 350 -- 351 -- The generation of global variables in the bind file is suppressed, 352 -- with the exception of the priority of the environment task, which 353 -- is needed by the Ravenscar run-time. 354 -- 355 -- The calls to __gnat_initialize and __gnat_finalize are omitted 356 -- 357 -- All finalization and initialization (controlled types) is omitted 358 -- 359 -- The routine __gnat_handler_installed is not imported 360 361 Preallocated_Stacks_On_Target : Boolean := False; 362 -- If this flag is True, then the expander preallocates all task stacks 363 -- at compile time. If the flag is False, then task stacks are not pre- 364 -- allocated, and task stack allocation is the responsibility of the 365 -- run-time (which typically delegates the task to the underlying 366 -- operating system environment). 367 368 --------------------- 369 -- Duration Format -- 370 --------------------- 371 372 -- By default, type Duration is a 64-bit fixed-point type with a delta 373 -- and small of 10**(-9) (i.e. it is a count in nanoseconds. This flag 374 -- allows that standard format to be modified. 375 376 Duration_32_Bits_On_Target : Boolean := False; 377 -- If True, then Duration is represented in 32 bits and the delta and 378 -- small values are set to 20.0*(10**(-3)) (i.e. it is a count in units 379 -- of 20 milliseconds. 380 381 ------------------------------------ 382 -- Back-End Code Generation Flags -- 383 ------------------------------------ 384 385 -- These flags indicate possible limitations in what the code generator 386 -- can handle. They will all be True for a full run-time, but one or more 387 -- of these may be false for a configurable run-time, and if a feature is 388 -- used at the source level, and the corresponding flag is false, then an 389 -- error message will be issued saying the feature is not supported. 390 391 Atomic_Sync_Default_On_Target : Boolean := True; 392 -- Access to atomic variables requires memory barrier synchronization in 393 -- the general case to ensure proper behavior when such accesses are used 394 -- on a multi-processor to synchronize tasks (e.g. by using spin locks). 395 -- The setting of this flag determines the default behavior. Normally this 396 -- is True, which will mean that appropriate synchronization instructions 397 -- are generated by default. If it is False, then the default will be that 398 -- these synchronization instructions are not generated. This may be a more 399 -- appropriate default in some cases, e.g. on embedded targets which do not 400 -- allow the possibility of multi-processors. The default can be overridden 401 -- using pragmas Enable/Disable_Atomic_Synchronization and also by use of 402 -- the debug flags gnat.d and gnatd.e. 403 404 Support_Aggregates_On_Target : Boolean := True; 405 -- In the general case, the use of aggregates may generate calls 406 -- to run-time routines in the C library, including memset, memcpy, 407 -- memmove, and bcopy. This flag is set to True if these routines 408 -- are available. If any of these routines is not available, then 409 -- this flag is False, and the use of aggregates is not permitted. 410 411 Support_Atomic_Primitives_On_Target : Boolean := False; 412 -- If this flag is True, then the back-end support GCC built-in atomic 413 -- operations for memory model such as atomic load or atomic compare 414 -- exchange (see the GCC manual for more information). If the flag is 415 -- False, then the back-end doesn't provide this support. Note this flag is 416 -- set to True only if the target supports all atomic primitives up to 64 417 -- bits. ??? To be modified. 418 419 Support_Composite_Assign_On_Target : Boolean := True; 420 -- The assignment of composite objects other than small records and 421 -- arrays whose size is 64-bits or less and is set by an explicit 422 -- size clause may generate calls to memcpy, memmove, and bcopy. 423 -- If versions of all these routines are available, then this flag 424 -- is set to True. If any of these routines is not available, then 425 -- the flag is set False, and composite assignments are not allowed. 426 427 Support_Composite_Compare_On_Target : Boolean := True; 428 -- If this flag is True, then the back end supports bit-wise comparison 429 -- of composite objects for equality, either generating inline code or 430 -- calling appropriate (and available) run-time routines. If this flag 431 -- is False, then the back end does not provide this support, and the 432 -- front end uses component by component comparison for composites. 433 434 Support_Long_Shifts_On_Target : Boolean := True; 435 -- If True, the back end supports 64-bit shift operations. If False, then 436 -- the source program may not contain explicit 64-bit shifts. In addition, 437 -- the code generated for packed arrays will avoid the use of long shifts. 438 439 Support_Nondefault_SSO_On_Target : Boolean := True; 440 -- If True, the back end supports the non-default Scalar_Storage_Order 441 -- (i.e. allows non-confirming Scalar_Storage_Order attribute definition 442 -- clauses). 443 444 -------------------- 445 -- Indirect Calls -- 446 -------------------- 447 448 Always_Compatible_Rep_On_Target : Boolean := True; 449 -- If True, the Can_Use_Internal_Rep flag (see Einfo) is set to False in 450 -- all cases. This corresponds to the traditional code generation 451 -- strategy. False allows the front end to choose a policy that partly or 452 -- entirely eliminates dynamically generated trampolines. 453 454 ------------------------------- 455 -- Control of Stack Checking -- 456 ------------------------------- 457 458 -- GNAT provides three methods of implementing exceptions: 459 460 -- GCC Probing Mechanism 461 462 -- This approach uses the standard GCC mechanism for 463 -- stack checking. The method assumes that accessing 464 -- storage immediately beyond the end of the stack 465 -- will result in a trap that is converted to a storage 466 -- error by the runtime system. This mechanism has 467 -- minimal overhead, but requires complex hardware, 468 -- operating system and run-time support. Probing is 469 -- the default method where it is available. The stack 470 -- size for the environment task depends on the operating 471 -- system and cannot be set in a system-independent way. 472 473 -- GCC Stack-limit Mechanism 474 475 -- This approach uses the GCC stack limits mechanism. 476 -- It relies on comparing the stack pointer with the 477 -- values of a global symbol. If the check fails, a 478 -- trap is explicitly generated. The advantage is 479 -- that the mechanism requires no memory protection, 480 -- but operating system and run-time support are 481 -- needed to manage the per-task values of the symbol. 482 -- This is the default method after probing where it 483 -- is available. 484 485 -- GNAT Stack-limit Checking 486 487 -- This method relies on comparing the stack pointer 488 -- with per-task stack limits. If the check fails, an 489 -- exception is explicitly raised. The advantage is 490 -- that the method requires no extra system dependent 491 -- runtime support and can be used on systems without 492 -- memory protection as well, but at the cost of more 493 -- overhead for doing the check. This is the fallback 494 -- method if the above two are not supported. 495 496 Stack_Check_Probes_On_Target : Boolean := False; 497 -- Indicates if the GCC probing mechanism is used 498 499 Stack_Check_Limits_On_Target : Boolean := False; 500 -- Indicates if the GCC stack-limit mechanism is used 501 502 -- Both flags cannot be simultaneously set to True. If neither 503 -- is, the target independent fallback method is used. 504 505 Stack_Check_Default_On_Target : Boolean := False; 506 -- Indicates if stack checking is on by default 507 508 ---------------------------- 509 -- Command Line Arguments -- 510 ---------------------------- 511 512 -- For most ports of GNAT, command line arguments are supported. The 513 -- following flag is set to False for targets that do not support 514 -- command line arguments (VxWorks and AAMP). Note that support of 515 -- command line arguments is not required on such targets (RM A.15(13)). 516 517 Command_Line_Args_On_Target : Boolean := True; 518 -- Set False if no command line arguments on target. Note that if this 519 -- is False in with Configurable_Run_Time_On_Target set to True, then 520 -- this causes suppression of generation of the argv/argc variables 521 -- used to record command line arguments. 522 523 -- Similarly, most ports support the use of an exit status, but AAMP 524 -- is an exception (as allowed by RM A.15(18-20)) 525 526 Exit_Status_Supported_On_Target : Boolean := True; 527 -- Set False if returning of an exit status is not supported on target. 528 -- Note that if this False in with Configurable_Run_Time_On_Target 529 -- set to True, then this causes suppression of the gnat_exit_status 530 -- variable used to record the exit status. 531 532 ----------------------- 533 -- Main Program Name -- 534 ----------------------- 535 536 -- When the binder generates the main program to be used to create the 537 -- executable, the main program name is main by default (to match the 538 -- usual Unix practice). If this parameter is set to True, then the 539 -- name is instead by default taken from the actual Ada main program 540 -- name (just the name of the child if the main program is a child unit). 541 -- In either case, this value can be overridden using -M name. 542 543 Use_Ada_Main_Program_Name_On_Target : Boolean := False; 544 -- Set True to use the Ada main program name as the main name 545 546 ---------------------------------------------- 547 -- Boolean-Valued Floating-Point Attributes -- 548 ---------------------------------------------- 549 550 -- The constants below give the values for representation oriented 551 -- floating-point attributes that are the same for all float types 552 -- on the target. These are all boolean values. 553 554 -- A value is only True if the target reliably supports the corresponding 555 -- feature. Reliably here means that support is guaranteed for all 556 -- possible settings of the relevant compiler switches (like -mieee), 557 -- since we cannot control the user setting of those switches. 558 559 -- The attributes cannot dependent on the current setting of compiler 560 -- switches, since the values must be static and consistent throughout 561 -- the partition. We probably should add such consistency checks in future, 562 -- but for now we don't do this. 563 564 -- Note: the compiler itself does not use floating-point, so the 565 -- settings of the defaults here are not really relevant. 566 567 -- Note: in some cases, proper support of some of these floating point 568 -- features may require a specific switch (e.g. -mieee on the Alpha) 569 -- to be used to obtain full RM compliant support. 570 571 Denorm_On_Target : Boolean := False; 572 -- Set to False on targets that do not reliably support denormals 573 574 Machine_Rounds_On_Target : Boolean := True; 575 -- Set to False for targets where S'Machine_Rounds is False 576 577 Machine_Overflows_On_Target : Boolean := False; 578 -- Set to True for targets where S'Machine_Overflows is True 579 580 Signed_Zeros_On_Target : Boolean := True; 581 -- Set to False on targets that do not reliably support signed zeros 582 583 ------------------------------------------- 584 -- Boolean-Valued Fixed-Point Attributes -- 585 ------------------------------------------- 586 587 Fractional_Fixed_Ops_On_Target : Boolean := False; 588 -- Set to True for targets that support fixed-by-fixed multiplication 589 -- and division for fixed-point types with a small value equal to 590 -- 2 ** (-(T'Object_Size - 1)) and whose values have an absolute 591 -- value less than 1.0. 592 593 ----------------- 594 -- Data Layout -- 595 ----------------- 596 597 -- Normally when using the GCC backend, Gigi and GCC perform much of the 598 -- data layout using the standard layout capabilities of GCC. If the 599 -- parameter Backend_Layout is set to False, then the front end must 600 -- perform all data layout. For further details see the package Layout. 601 602 Frontend_Layout_On_Target : Boolean := False; 603 -- Set True if front end does layout 604 605 ----------------- 606 -- Subprograms -- 607 ----------------- 608 609 -- These subprograms are used to initialize the target parameter values 610 -- from the system.ads file. Note that this is only done once, so if more 611 -- than one call is made to either routine, the second and subsequent 612 -- calls are ignored. 613 614 procedure Get_Target_Parameters 615 (System_Text : Source_Buffer_Ptr; 616 Source_First : Source_Ptr; 617 Source_Last : Source_Ptr); 618 -- Called at the start of execution to obtain target parameters from 619 -- the source of package System. The parameters provide the source 620 -- text to be scanned (in System_Text (Source_First .. Source_Last)). 621 622 procedure Get_Target_Parameters; 623 -- This version reads in system.ads using Osint. The idea is that the 624 -- caller uses the first version if they have to read system.ads anyway 625 -- (e.g. the compiler) and uses this simpler interface if system.ads is 626 -- not otherwise needed. 627 628end Targparm; 629