libgcc/crtstuff.c

   1 /* Specialized bits of code needed to support construction and
   2    destruction of file-scope objects in C++ code.
   3    Copyright (C) 1991-2018 Free Software Foundation, Inc.
   4    Contributed by Ron Guilmette (rfg@monkeys.com).
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 Under Section 7 of GPL version 3, you are granted additional
  19 permissions described in the GCC Runtime Library Exception, version
  20 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 /* This file is a bit like libgcc2.c in that it is compiled
  28    multiple times and yields multiple .o files.
  29
  30    This file is useful on target machines where the object file format
  31    supports multiple "user-defined" sections (e.g. COFF, ELF, ROSE).  On
  32    such systems, this file allows us to avoid running collect (or any
  33    other such slow and painful kludge).  Additionally, if the target
  34    system supports a .init section, this file allows us to support the
  35    linking of C++ code with a non-C++ main program.
  36
  37    Note that if INIT_SECTION_ASM_OP is defined in the tm.h file, then
  38    this file *will* make use of the .init section.  If that symbol is
  39    not defined however, then the .init section will not be used.
  40
  41    Currently, only ELF and COFF are supported.  It is likely however that
  42    ROSE could also be supported, if someone was willing to do the work to
  43    make whatever (small?) adaptations are needed.  (Some work may be
  44    needed on the ROSE assembler and linker also.)
  45
  46    This file must be compiled with gcc.  */
  47
  48 /* Target machine header files require this define. */
  49 #define IN_LIBGCC2
  50
  51 /* FIXME: Including auto-host is incorrect, but until we have
  52    identified the set of defines that need to go into auto-target.h,
  53    this will have to do.  */
  54 #include "auto-host.h"
  55 #undef caddr_t
  56 #undef pid_t
  57 #undef rlim_t
  58 #undef ssize_t
  59 #undef vfork
  60 #include "tconfig.h"
  61 #include "tsystem.h"
  62 #include "coretypes.h"
  63 #include "tm.h"
  64 #include "libgcc_tm.h"
  65 #include "unwind-dw2-fde.h"
  66
  67 #ifndef FORCE_CODE_SECTION_ALIGN
  68 # define FORCE_CODE_SECTION_ALIGN
  69 #endif
  70
  71 #ifndef CRT_CALL_STATIC_FUNCTION
  72 # define CRT_CALL_STATIC_FUNCTION(SECTION_OP, FUNC)     \
  73 static void __attribute__((__used__))                   \
  74 call_ ## FUNC (void)                                    \
  75 {                                                       \
  76   asm (SECTION_OP);                                     \
  77   FUNC ();                                              \
  78   FORCE_CODE_SECTION_ALIGN                              \
  79   asm (__LIBGCC_TEXT_SECTION_ASM_OP__);                         \
  80 }
  81 #endif
  82
  83 #if defined(TARGET_DL_ITERATE_PHDR) && \
  84    (defined(__DragonFly__) || defined(__FreeBSD__) || defined(__NetBSD__))
  85 #define BSD_DL_ITERATE_PHDR_AVAILABLE
  86 #endif
  87
  88 #if defined(OBJECT_FORMAT_ELF) \
  89     && !defined(OBJECT_FORMAT_FLAT) \
  90     && defined(HAVE_LD_EH_FRAME_HDR) \
  91     && !defined(inhibit_libc) && !defined(CRTSTUFFT_O) \
  92     && defined(BSD_DL_ITERATE_PHDR_AVAILABLE)
  93 #include <link.h>
  94 # define USE_PT_GNU_EH_FRAME
  95 #endif
  96
  97 #if defined(OBJECT_FORMAT_ELF) \
  98     && !defined(OBJECT_FORMAT_FLAT) \
  99     && defined(HAVE_LD_EH_FRAME_HDR) && defined(TARGET_DL_ITERATE_PHDR) \
 100     && !defined(inhibit_libc) && !defined(CRTSTUFFT_O) \
 101     && defined(__sun__) && defined(__svr4__)
 102 #include <link.h>
 103 # define USE_PT_GNU_EH_FRAME
 104 #endif
 105
 106 #if defined(OBJECT_FORMAT_ELF) \
 107     && !defined(OBJECT_FORMAT_FLAT) \
 108     && defined(HAVE_LD_EH_FRAME_HDR) \
 109     && !defined(inhibit_libc) && !defined(CRTSTUFFT_O) \
 110     && defined(__GLIBC__) && __GLIBC__ >= 2
 111 #include <link.h>
 112 /* uClibc pretends to be glibc 2.2 and DT_CONFIG is defined in its link.h.
 113    But it doesn't use PT_GNU_EH_FRAME ELF segment currently.  */
 114 # if !defined(__UCLIBC__) \
 115      && (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2) \
 116      || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && defined(DT_CONFIG)))
 117 #  define USE_PT_GNU_EH_FRAME
 118 # endif
 119 #endif
 120
 121 #if defined(OBJECT_FORMAT_ELF) \
 122     && !defined(OBJECT_FORMAT_FLAT) \
 123     && defined(HAVE_LD_EH_FRAME_HDR) \
 124     && !defined(CRTSTUFFT_O) \
 125     && defined(inhibit_libc) \
 126     && (defined(__GLIBC__) || defined(__gnu_linux__) || defined(__GNU__))
 127 /* On systems using glibc, an inhibit_libc build of libgcc is only
 128    part of a bootstrap process.  Build the same crt*.o as would be
 129    built with headers present, so that it is not necessary to build
 130    glibc more than once for the bootstrap to converge.  */
 131 # define USE_PT_GNU_EH_FRAME
 132 #endif
 133
 134 #ifdef USE_EH_FRAME_REGISTRY_ALWAYS
 135 # ifndef __LIBGCC_EH_FRAME_SECTION_NAME__
 136 #  error "Can't use explicit exception-frame-registration without __LIBGCC_EH_FRAME_SECTION_NAME__"
 137 # endif
 138 #endif
 139 #if defined(__LIBGCC_EH_FRAME_SECTION_NAME__) && (!defined(USE_PT_GNU_EH_FRAME) || defined(USE_EH_FRAME_REGISTRY_ALWAYS))
 140 # define USE_EH_FRAME_REGISTRY
 141 #endif
 142 #if defined(__LIBGCC_EH_FRAME_SECTION_NAME__) \
 143     && __LIBGCC_EH_TABLES_CAN_BE_READ_ONLY__
 144 # define EH_FRAME_SECTION_CONST const
 145 #else
 146 # define EH_FRAME_SECTION_CONST
 147 #endif
 148
 149 #if !defined(DTOR_LIST_END) && defined(OBJECT_FORMAT_ELF) \
 150     && defined(HAVE_GAS_HIDDEN) && !defined(FINI_ARRAY_SECTION_ASM_OP)
 151 # define HIDDEN_DTOR_LIST_END
 152 #endif
 153
 154 #if !defined(USE_TM_CLONE_REGISTRY) && defined(OBJECT_FORMAT_ELF)
 155 # define USE_TM_CLONE_REGISTRY 1
 156 #endif
 157
 158 /* We do not want to add the weak attribute to the declarations of these
 159    routines in unwind-dw2-fde.h because that will cause the definition of
 160    these symbols to be weak as well.
 161
 162    This exposes a core issue, how to handle creating weak references vs
 163    how to create weak definitions.  Either we have to have the definition
 164    of TARGET_WEAK_ATTRIBUTE be conditional in the shared header files or
 165    have a second declaration if we want a function's references to be weak,
 166    but not its definition.
 167
 168    Making TARGET_WEAK_ATTRIBUTE conditional seems like a good solution until
 169    one thinks about scaling to larger problems -- i.e., the condition under
 170    which TARGET_WEAK_ATTRIBUTE is active will eventually get far too
 171    complicated.
 172
 173    So, we take an approach similar to #pragma weak -- we have a second
 174    declaration for functions that we want to have weak references.
 175
 176    Neither way is particularly good.  */
 177
 178 /* References to __register_frame_info and __deregister_frame_info should
 179    be weak in this file if at all possible.  */
 180 extern void __register_frame_info (const void *, struct object *)
 181                                   TARGET_ATTRIBUTE_WEAK;
 182 extern void __register_frame_info_bases (const void *, struct object *,
 183                                          void *, void *)
 184                                   TARGET_ATTRIBUTE_WEAK;
 185 extern void *__deregister_frame_info (const void *)
 186                                      TARGET_ATTRIBUTE_WEAK;
 187 extern void *__deregister_frame_info_bases (const void *)
 188                                      TARGET_ATTRIBUTE_WEAK;
 189 extern void __do_global_ctors_1 (void);
 190
 191 /* Likewise for transactional memory clone tables.  */
 192 extern void _ITM_registerTMCloneTable (void *, size_t) TARGET_ATTRIBUTE_WEAK;
 193 extern void _ITM_deregisterTMCloneTable (void *) TARGET_ATTRIBUTE_WEAK;
 194
 195 #ifdef OBJECT_FORMAT_ELF
 196
 197 /*  Declare a pointer to void function type.  */
 198 typedef void (*func_ptr) (void);
 199 #define STATIC static
 200
 201 #else  /* OBJECT_FORMAT_ELF */
 202
 203 #include "gbl-ctors.h"
 204
 205 #define STATIC
 206
 207 #endif /* OBJECT_FORMAT_ELF */
 208
 209 #ifdef CRT_BEGIN
 210
 211 /* NOTE:  In order to be able to support SVR4 shared libraries, we arrange
 212    to have one set of symbols { __CTOR_LIST__, __DTOR_LIST__, __CTOR_END__,
 213    __DTOR_END__ } per root executable and also one set of these symbols
 214    per shared library.  So in any given whole process image, we may have
 215    multiple definitions of each of these symbols.  In order to prevent
 216    these definitions from conflicting with one another, and in order to
 217    ensure that the proper lists are used for the initialization/finalization
 218    of each individual shared library (respectively), we give these symbols
 219    only internal (i.e. `static') linkage, and we also make it a point to
 220    refer to only the __CTOR_END__ symbol in crtend.o and the __DTOR_LIST__
 221    symbol in crtbegin.o, where they are defined.  */
 222
 223 /* No need for .ctors/.dtors section if linker can place them in
 224    .init_array/.fini_array section.  */
 225 #ifndef USE_INITFINI_ARRAY
 226 /* The -1 is a flag to __do_global_[cd]tors indicating that this table
 227    does not start with a count of elements.  */
 228 #ifdef CTOR_LIST_BEGIN
 229 CTOR_LIST_BEGIN;
 230 #elif defined(__LIBGCC_CTORS_SECTION_ASM_OP__)
 231 /* Hack: force cc1 to switch to .data section early, so that assembling
 232    __CTOR_LIST__ does not undo our behind-the-back change to .ctors.  */
 233 static func_ptr force_to_data[1] __attribute__ ((__used__)) = { };
 234 asm (__LIBGCC_CTORS_SECTION_ASM_OP__);
 235 STATIC func_ptr __CTOR_LIST__[1]
 236   __attribute__ ((__used__, aligned(sizeof(func_ptr))))
 237   = { (func_ptr) (-1) };
 238 #else
 239 STATIC func_ptr __CTOR_LIST__[1]
 240   __attribute__ ((__used__, section(".ctors"), aligned(sizeof(func_ptr))))
 241   = { (func_ptr) (-1) };
 242 #endif /* __CTOR_LIST__ alternatives */
 243
 244 #ifdef DTOR_LIST_BEGIN
 245 DTOR_LIST_BEGIN;
 246 #elif defined(__LIBGCC_DTORS_SECTION_ASM_OP__)
 247 asm (__LIBGCC_DTORS_SECTION_ASM_OP__);
 248 STATIC func_ptr __DTOR_LIST__[1]
 249   __attribute__ ((aligned(sizeof(func_ptr))))
 250   = { (func_ptr) (-1) };
 251 #else
 252 STATIC func_ptr __DTOR_LIST__[1]
 253   __attribute__((section(".dtors"), aligned(sizeof(func_ptr))))
 254   = { (func_ptr) (-1) };
 255 #endif /* __DTOR_LIST__ alternatives */
 256 #endif /* USE_INITFINI_ARRAY */
 257
 258 #ifdef USE_EH_FRAME_REGISTRY
 259 /* Stick a label at the beginning of the frame unwind info so we can register
 260    and deregister it with the exception handling library code.  */
 261 STATIC EH_FRAME_SECTION_CONST char __EH_FRAME_BEGIN__[]
 262      __attribute__((section(__LIBGCC_EH_FRAME_SECTION_NAME__), aligned(4)))
 263      = { };
 264 #endif /* USE_EH_FRAME_REGISTRY */
 265
 266 #if USE_TM_CLONE_REGISTRY
 267 STATIC func_ptr __TMC_LIST__[]
 268   __attribute__((used, section(".tm_clone_table"), aligned(sizeof(void*))))
 269   = { };
 270 # ifdef HAVE_GAS_HIDDEN
 271 extern func_ptr __TMC_END__[] __attribute__((__visibility__ ("hidden")));
 272 # endif
 273
 274 static inline void
 275 deregister_tm_clones (void)
 276 {
 277   void (*fn) (void *);
 278
 279 #ifdef HAVE_GAS_HIDDEN
 280   func_ptr *end = __TMC_END__;
 281   // Do not optimize the comparison to false.
 282   __asm ("" : "+g" (end));
 283   if (__TMC_LIST__ == end)
 284     return;
 285 #else
 286   if (__TMC_LIST__[0] == NULL)
 287     return;
 288 #endif
 289
 290   fn = _ITM_deregisterTMCloneTable;
 291   __asm ("" : "+r" (fn));
 292   if (fn)
 293     fn (__TMC_LIST__);
 294 }
 295
 296 static inline void
 297 register_tm_clones (void)
 298 {
 299   void (*fn) (void *, size_t);
 300   size_t size;
 301
 302 #ifdef HAVE_GAS_HIDDEN
 303   func_ptr *end = __TMC_END__;
 304   // Do not optimize the comparison to false.
 305   __asm ("" : "+g" (end));
 306   size = (end - __TMC_LIST__) / 2;
 307 #else
 308   for (size = 0; __TMC_LIST__[size * 2] != NULL; size++)
 309     continue;
 310 #endif
 311   if (size == 0)
 312     return;
 313
 314   fn = _ITM_registerTMCloneTable;
 315   __asm ("" : "+r" (fn));
 316   if (fn)
 317     fn (__TMC_LIST__, size);
 318 }
 319 #endif /* USE_TM_CLONE_REGISTRY */
 320
 321 #if defined(__LIBGCC_INIT_SECTION_ASM_OP__) \
 322     || defined(__LIBGCC_INIT_ARRAY_SECTION_ASM_OP__)
 323
 324 #ifdef OBJECT_FORMAT_ELF
 325
 326 /* Declare the __dso_handle variable.  It should have a unique value
 327    in every shared-object; in a main program its value is zero.  The
 328    object should in any case be protected.  This means the instance
 329    in one DSO or the main program is not used in another object.  The
 330    dynamic linker takes care of this.  */
 331
 332 #ifdef TARGET_LIBGCC_SDATA_SECTION
 333 extern void *__dso_handle __attribute__ ((__section__ (TARGET_LIBGCC_SDATA_SECTION)));
 334 #endif
 335 #ifdef HAVE_GAS_HIDDEN
 336 extern void *__dso_handle __attribute__ ((__visibility__ ("hidden")));
 337 #endif
 338 #ifdef CRTSTUFFS_O
 339 void *__dso_handle = &__dso_handle;
 340 #else
 341 void *__dso_handle = 0;
 342 #endif
 343
 344 /* The __cxa_finalize function may not be available so we use only a
 345    weak declaration.  */
 346 extern void __cxa_finalize (void *) TARGET_ATTRIBUTE_WEAK;
 347
 348 /* Run all the global destructors on exit from the program.  */
 349
 350 /* Some systems place the number of pointers in the first word of the
 351    table.  On SVR4 however, that word is -1.  In all cases, the table is
 352    null-terminated.  On SVR4, we start from the beginning of the list and
 353    invoke each per-compilation-unit destructor routine in order
 354    until we find that null.
 355
 356    Note that this function MUST be static.  There will be one of these
 357    functions in each root executable and one in each shared library, but
 358    although they all have the same code, each one is unique in that it
 359    refers to one particular associated `__DTOR_LIST__' which belongs to the
 360    same particular root executable or shared library file.
 361
 362    On some systems, this routine is run more than once from the .fini,
 363    when exit is called recursively, so we arrange to remember where in
 364    the list we left off processing, and we resume at that point,
 365    should we be re-invoked.  */
 366
 367 static void __attribute__((used))
 368 __do_global_dtors_aux (void)
 369 {
 370   static _Bool completed;
 371
 372   if (__builtin_expect (completed, 0))
 373     return;
 374
 375 #ifdef CRTSTUFFS_O
 376   if (__cxa_finalize)
 377     __cxa_finalize (__dso_handle);
 378 #endif
 379
 380 #ifdef FINI_ARRAY_SECTION_ASM_OP
 381   /* If we are using .fini_array then destructors will be run via that
 382      mechanism.  */
 383 #elif defined(HIDDEN_DTOR_LIST_END)
 384   {
 385     /* Safer version that makes sure only .dtors function pointers are
 386        called even if the static variable is maliciously changed.  */
 387     extern func_ptr __DTOR_END__[] __attribute__((visibility ("hidden")));
 388     static size_t dtor_idx;
 389     const size_t max_idx = __DTOR_END__ - __DTOR_LIST__ - 1;
 390     func_ptr *dtor_list;
 391
 392     __asm ("" : "=g" (dtor_list) : "0" (__DTOR_LIST__));
 393     while (dtor_idx < max_idx)
 394       dtor_list[++dtor_idx] ();
 395   }
 396 #else /* !defined (FINI_ARRAY_SECTION_ASM_OP) */
 397   {
 398     static func_ptr *p = __DTOR_LIST__ + 1;
 399     func_ptr f;
 400
 401     while ((f = *p))
 402       {
 403         p++;
 404         f ();
 405       }
 406   }
 407 #endif /* !defined(FINI_ARRAY_SECTION_ASM_OP) */
 408
 409 #if USE_TM_CLONE_REGISTRY
 410   deregister_tm_clones ();
 411 #endif /* USE_TM_CLONE_REGISTRY */
 412
 413 #ifdef USE_EH_FRAME_REGISTRY
 414 #ifdef CRT_GET_RFIB_DATA
 415   /* If we used the new __register_frame_info_bases interface,
 416      make sure that we deregister from the same place.  */
 417   if (__deregister_frame_info_bases)
 418     __deregister_frame_info_bases (__EH_FRAME_BEGIN__);
 419 #else
 420   if (__deregister_frame_info)
 421     __deregister_frame_info (__EH_FRAME_BEGIN__);
 422 #endif
 423 #endif
 424
 425   completed = 1;
 426 }
 427
 428 /* Stick a call to __do_global_dtors_aux into the .fini section.  */
 429 #ifdef FINI_SECTION_ASM_OP
 430 CRT_CALL_STATIC_FUNCTION (FINI_SECTION_ASM_OP, __do_global_dtors_aux)
 431 #elif defined (FINI_ARRAY_SECTION_ASM_OP)
 432 static func_ptr __do_global_dtors_aux_fini_array_entry[]
 433   __attribute__ ((__used__, section(".fini_array"), aligned(sizeof(func_ptr))))
 434   = { __do_global_dtors_aux };
 435 #else /* !FINI_SECTION_ASM_OP && !FINI_ARRAY_SECTION_ASM_OP */
 436 static void __attribute__((used))
 437 __do_global_dtors_aux_1 (void)
 438 {
 439   atexit (__do_global_dtors_aux);
 440 }
 441 CRT_CALL_STATIC_FUNCTION (__LIBGCC_INIT_SECTION_ASM_OP__,
 442                           __do_global_dtors_aux_1)
 443 #endif
 444
 445 #if defined(USE_EH_FRAME_REGISTRY) \
 446     || defined(USE_TM_CLONE_REGISTRY)
 447 /* Stick a call to __register_frame_info into the .init section.  For some
 448    reason calls with no arguments work more reliably in .init, so stick the
 449    call in another function.  */
 450
 451 static void __attribute__((used))
 452 frame_dummy (void)
 453 {
 454 #ifdef USE_EH_FRAME_REGISTRY
 455   static struct object object;
 456 #ifdef CRT_GET_RFIB_DATA
 457   void *tbase, *dbase;
 458   tbase = 0;
 459   CRT_GET_RFIB_DATA (dbase);
 460   if (__register_frame_info_bases)
 461     __register_frame_info_bases (__EH_FRAME_BEGIN__, &object, tbase, dbase);
 462 #else
 463   if (__register_frame_info)
 464     __register_frame_info (__EH_FRAME_BEGIN__, &object);
 465 #endif /* CRT_GET_RFIB_DATA */
 466 #endif /* USE_EH_FRAME_REGISTRY */
 467
 468 #if USE_TM_CLONE_REGISTRY
 469   register_tm_clones ();
 470 #endif /* USE_TM_CLONE_REGISTRY */
 471 }
 472
 473 #ifdef __LIBGCC_INIT_SECTION_ASM_OP__
 474 CRT_CALL_STATIC_FUNCTION (__LIBGCC_INIT_SECTION_ASM_OP__, frame_dummy)
 475 #else /* defined(__LIBGCC_INIT_SECTION_ASM_OP__) */
 476 static func_ptr __frame_dummy_init_array_entry[]
 477   __attribute__ ((__used__, section(".init_array"), aligned(sizeof(func_ptr))))
 478   = { frame_dummy };
 479 #endif /* !defined(__LIBGCC_INIT_SECTION_ASM_OP__) */
 480 #endif /* USE_EH_FRAME_REGISTRY || USE_TM_CLONE_REGISTRY */
 481
 482 #else  /* OBJECT_FORMAT_ELF */
 483
 484 /* The function __do_global_ctors_aux is compiled twice (once in crtbegin.o
 485    and once in crtend.o).  It must be declared static to avoid a link
 486    error.  Here, we define __do_global_ctors as an externally callable
 487    function.  It is externally callable so that __main can invoke it when
 488    INVOKE__main is defined.  This has the additional effect of forcing cc1
 489    to switch to the .text section.  */
 490
 491 static void __do_global_ctors_aux (void);
 492 void
 493 __do_global_ctors (void)
 494 {
 495 #ifdef INVOKE__main
 496   /* If __main won't actually call __do_global_ctors then it doesn't matter
 497      what's inside the function.  The inside of __do_global_ctors_aux is
 498      called automatically in that case.  And the Alliant fx2800 linker
 499      crashes on this reference.  So prevent the crash.  */
 500   __do_global_ctors_aux ();
 501 #endif
 502 }
 503
 504 asm (__LIBGCC_INIT_SECTION_ASM_OP__);   /* cc1 doesn't know that we are switching! */
 505
 506 /* A routine to invoke all of the global constructors upon entry to the
 507    program.  We put this into the .init section (for systems that have
 508    such a thing) so that we can properly perform the construction of
 509    file-scope static-storage C++ objects within shared libraries.  */
 510
 511 static void __attribute__((used))
 512 __do_global_ctors_aux (void)    /* prologue goes in .init section */
 513 {
 514   FORCE_CODE_SECTION_ALIGN      /* explicit align before switch to .text */
 515   asm (__LIBGCC_TEXT_SECTION_ASM_OP__); /* don't put epilogue and body in .init */
 516   DO_GLOBAL_CTORS_BODY;
 517   atexit (__do_global_dtors);
 518 }
 519
 520 #endif /* OBJECT_FORMAT_ELF */
 521
 522 #elif defined(HAS_INIT_SECTION) /* ! __LIBGCC_INIT_SECTION_ASM_OP__ */
 523
 524 extern void __do_global_dtors (void);
 525
 526 /* This case is used by the Irix 6 port, which supports named sections but
 527    not an SVR4-style .fini section.  __do_global_dtors can be non-static
 528    in this case because we protect it with -hidden_symbol.  */
 529
 530 void
 531 __do_global_dtors (void)
 532 {
 533   func_ptr *p, f;
 534   for (p = __DTOR_LIST__ + 1; (f = *p); p++)
 535     f ();
 536
 537 #if USE_TM_CLONE_REGISTRY
 538   deregister_tm_clones ();
 539 #endif /* USE_TM_CLONE_REGISTRY */
 540
 541 #ifdef USE_EH_FRAME_REGISTRY
 542   if (__deregister_frame_info)
 543     __deregister_frame_info (__EH_FRAME_BEGIN__);
 544 #endif
 545 }
 546
 547 #if defined(USE_EH_FRAME_REGISTRY) \
 548     || defined(USE_TM_CLONE_REGISTRY)
 549 /* A helper function for __do_global_ctors, which is in crtend.o.  Here
 550    in crtbegin.o, we can reference a couple of symbols not visible there.
 551    Plus, since we're before libgcc.a, we have no problems referencing
 552    functions from there.  */
 553 void
 554 __do_global_ctors_1(void)
 555 {
 556 #ifdef USE_EH_FRAME_REGISTRY
 557   static struct object object;
 558   if (__register_frame_info)
 559     __register_frame_info (__EH_FRAME_BEGIN__, &object);
 560 #endif
 561
 562 #if USE_TM_CLONE_REGISTRY
 563   register_tm_clones ();
 564 #endif /* USE_TM_CLONE_REGISTRY */
 565 }
 566 #endif /* USE_EH_FRAME_REGISTRY || USE_TM_CLONE_REGISTRY */
 567
 568 #else /* ! __LIBGCC_INIT_SECTION_ASM_OP__ && ! HAS_INIT_SECTION */
 569 #error "What are you doing with crtstuff.c, then?"
 570 #endif
 571
 572 #elif defined(CRT_END) /* ! CRT_BEGIN */
 573
 574 /* No need for .ctors/.dtors section if linker can place them in
 575    .init_array/.fini_array section.  */
 576 #ifndef USE_INITFINI_ARRAY
 577 /* Put a word containing zero at the end of each of our two lists of function
 578    addresses.  Note that the words defined here go into the .ctors and .dtors
 579    sections of the crtend.o file, and since that file is always linked in
 580    last, these words naturally end up at the very ends of the two lists
 581    contained in these two sections.  */
 582
 583 #ifdef CTOR_LIST_END
 584 CTOR_LIST_END;
 585 #elif defined(__LIBGCC_CTORS_SECTION_ASM_OP__)
 586 /* Hack: force cc1 to switch to .data section early, so that assembling
 587    __CTOR_LIST__ does not undo our behind-the-back change to .ctors.  */
 588 static func_ptr force_to_data[1] __attribute__ ((__used__)) = { };
 589 asm (__LIBGCC_CTORS_SECTION_ASM_OP__);
 590 STATIC func_ptr __CTOR_END__[1]
 591   __attribute__((aligned(sizeof(func_ptr))))
 592   = { (func_ptr) 0 };
 593 #else
 594 STATIC func_ptr __CTOR_END__[1]
 595   __attribute__((section(".ctors"), aligned(sizeof(func_ptr))))
 596   = { (func_ptr) 0 };
 597 #endif
 598
 599 #ifdef DTOR_LIST_END
 600 DTOR_LIST_END;
 601 #elif defined(HIDDEN_DTOR_LIST_END)
 602 #ifdef __LIBGCC_DTORS_SECTION_ASM_OP__
 603 asm (__LIBGCC_DTORS_SECTION_ASM_OP__);
 604 #endif
 605 func_ptr __DTOR_END__[1]
 606   __attribute__ ((used,
 607 #ifndef __LIBGCC_DTORS_SECTION_ASM_OP__
 608                   section(".dtors"),
 609 #endif
 610                   aligned(sizeof(func_ptr)), visibility ("hidden")))
 611   = { (func_ptr) 0 };
 612 #elif defined(__LIBGCC_DTORS_SECTION_ASM_OP__)
 613 asm (__LIBGCC_DTORS_SECTION_ASM_OP__);
 614 STATIC func_ptr __DTOR_END__[1]
 615   __attribute__ ((used, aligned(sizeof(func_ptr))))
 616   = { (func_ptr) 0 };
 617 #else
 618 STATIC func_ptr __DTOR_END__[1]
 619   __attribute__((used, section(".dtors"), aligned(sizeof(func_ptr))))
 620   = { (func_ptr) 0 };
 621 #endif
 622 #endif /* USE_INITFINI_ARRAY */
 623
 624 #ifdef __LIBGCC_EH_FRAME_SECTION_NAME__
 625 /* Terminate the frame unwind info section with a 4byte 0 as a sentinel;
 626    this would be the 'length' field in a real FDE.  */
 627 # if __INT_MAX__ == 2147483647
 628 typedef int int32;
 629 # elif __LONG_MAX__ == 2147483647
 630 typedef long int32;
 631 # elif __SHRT_MAX__ == 2147483647
 632 typedef short int32;
 633 # else
 634 #  error "Missing a 4 byte integer"
 635 # endif
 636 STATIC EH_FRAME_SECTION_CONST int32 __FRAME_END__[]
 637      __attribute__ ((used, section(__LIBGCC_EH_FRAME_SECTION_NAME__),
 638                      aligned(sizeof(int32))))
 639      = { 0 };
 640 #endif /* __LIBGCC_EH_FRAME_SECTION_NAME__ */
 641
 642 #if USE_TM_CLONE_REGISTRY
 643 # ifndef HAVE_GAS_HIDDEN
 644 static
 645 # endif
 646 func_ptr __TMC_END__[]
 647   __attribute__((used, section(".tm_clone_table"), aligned(sizeof(void *))))
 648 # ifdef HAVE_GAS_HIDDEN
 649   __attribute__((__visibility__ ("hidden"))) = { };
 650 # else
 651   = { 0, 0 };
 652 # endif
 653 #endif /* USE_TM_CLONE_REGISTRY */
 654
 655 #ifdef __LIBGCC_INIT_ARRAY_SECTION_ASM_OP__
 656
 657 /* If we are using .init_array, there is nothing to do.  */
 658
 659 #elif defined(__LIBGCC_INIT_SECTION_ASM_OP__)
 660
 661 #ifdef OBJECT_FORMAT_ELF
 662 static void __attribute__((used))
 663 __do_global_ctors_aux (void)
 664 {
 665   func_ptr *p;
 666   for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
 667     (*p) ();
 668 }
 669
 670 /* Stick a call to __do_global_ctors_aux into the .init section.  */
 671 CRT_CALL_STATIC_FUNCTION (__LIBGCC_INIT_SECTION_ASM_OP__, __do_global_ctors_aux)
 672 #else  /* OBJECT_FORMAT_ELF */
 673
 674 /* Stick the real initialization code, followed by a normal sort of
 675    function epilogue at the very end of the .init section for this
 676    entire root executable file or for this entire shared library file.
 677
 678    Note that we use some tricks here to get *just* the body and just
 679    a function epilogue (but no function prologue) into the .init
 680    section of the crtend.o file.  Specifically, we switch to the .text
 681    section, start to define a function, and then we switch to the .init
 682    section just before the body code.
 683
 684    Earlier on, we put the corresponding function prologue into the .init
 685    section of the crtbegin.o file (which will be linked in first).
 686
 687    Note that we want to invoke all constructors for C++ file-scope static-
 688    storage objects AFTER any other possible initialization actions which
 689    may be performed by the code in the .init section contributions made by
 690    other libraries, etc.  That's because those other initializations may
 691    include setup operations for very primitive things (e.g. initializing
 692    the state of the floating-point coprocessor, etc.) which should be done
 693    before we start to execute any of the user's code.  */
 694
 695 static void
 696 __do_global_ctors_aux (void)    /* prologue goes in .text section */
 697 {
 698   asm (__LIBGCC_INIT_SECTION_ASM_OP__);
 699   DO_GLOBAL_CTORS_BODY;
 700   atexit (__do_global_dtors);
 701 }                               /* epilogue and body go in .init section */
 702
 703 FORCE_CODE_SECTION_ALIGN
 704 asm (__LIBGCC_TEXT_SECTION_ASM_OP__);
 705
 706 #endif /* OBJECT_FORMAT_ELF */
 707
 708 #elif defined(HAS_INIT_SECTION) /* ! __LIBGCC_INIT_SECTION_ASM_OP__ */
 709
 710 extern void __do_global_ctors (void);
 711
 712 /* This case is used by the Irix 6 port, which supports named sections but
 713    not an SVR4-style .init section.  __do_global_ctors can be non-static
 714    in this case because we protect it with -hidden_symbol.  */
 715 void
 716 __do_global_ctors (void)
 717 {
 718   func_ptr *p;
 719 #if defined(USE_EH_FRAME_REGISTRY) \
 720     || defined(USE_TM_CLONE_REGISTRY)
 721   __do_global_ctors_1();
 722 #endif
 723   for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
 724     (*p) ();
 725 }
 726
 727 #else /* ! __LIBGCC_INIT_SECTION_ASM_OP__ && ! HAS_INIT_SECTION */
 728 #error "What are you doing with crtstuff.c, then?"
 729 #endif
 730
 731 #else /* ! CRT_BEGIN && ! CRT_END */
 732 #error "One of CRT_BEGIN or CRT_END must be defined."
 733 #endif