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) 1991-2019 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(__alignof__(func_ptr))))
 237   = { (func_ptr) (-1) };
 238 #else
 239 STATIC func_ptr __CTOR_LIST__[1]
 240   __attribute__ ((__used__, section(".ctors"), aligned(__alignof__(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(__alignof__(func_ptr))))
 250   = { (func_ptr) (-1) };
 251 #else
 252 STATIC func_ptr __DTOR_LIST__[1]
 253   __attribute__((section(".dtors"), aligned(__alignof__(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(__alignof__(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 #if defined(__FDPIC__)
 433 __asm__("\t.equ\t__do_global_dtors_aux_alias, __do_global_dtors_aux\n");
 434 extern char __do_global_dtors_aux_alias;
 435 static void *__do_global_dtors_aux_fini_array_entry[]
 436 __attribute__ ((__used__, section(".fini_array"), aligned(sizeof(void *))))
 437      = { &__do_global_dtors_aux_alias };
 438 #else /* defined(__FDPIC__) */
 439 static func_ptr __do_global_dtors_aux_fini_array_entry[]
 440   __attribute__ ((__used__, section(".fini_array"),
 441                   aligned(__alignof__(func_ptr)))) = { __do_global_dtors_aux };
 442 #endif /* defined(__FDPIC__) */
 443 #else /* !FINI_SECTION_ASM_OP && !FINI_ARRAY_SECTION_ASM_OP */
 444 static void __attribute__((used))
 445 __do_global_dtors_aux_1 (void)
 446 {
 447   atexit (__do_global_dtors_aux);
 448 }
 449 CRT_CALL_STATIC_FUNCTION (__LIBGCC_INIT_SECTION_ASM_OP__,
 450                           __do_global_dtors_aux_1)
 451 #endif
 452
 453 #if defined(USE_EH_FRAME_REGISTRY) \
 454     || defined(USE_TM_CLONE_REGISTRY)
 455 /* Stick a call to __register_frame_info into the .init section.  For some
 456    reason calls with no arguments work more reliably in .init, so stick the
 457    call in another function.  */
 458
 459 static void __attribute__((used))
 460 frame_dummy (void)
 461 {
 462 #ifdef USE_EH_FRAME_REGISTRY
 463   static struct object object;
 464 #ifdef CRT_GET_RFIB_DATA
 465   void *tbase, *dbase;
 466   tbase = 0;
 467   CRT_GET_RFIB_DATA (dbase);
 468   if (__register_frame_info_bases)
 469     __register_frame_info_bases (__EH_FRAME_BEGIN__, &object, tbase, dbase);
 470 #else
 471   if (__register_frame_info)
 472     __register_frame_info (__EH_FRAME_BEGIN__, &object);
 473 #endif /* CRT_GET_RFIB_DATA */
 474 #endif /* USE_EH_FRAME_REGISTRY */
 475
 476 #if USE_TM_CLONE_REGISTRY
 477   register_tm_clones ();
 478 #endif /* USE_TM_CLONE_REGISTRY */
 479 }
 480
 481 #ifdef __LIBGCC_INIT_SECTION_ASM_OP__
 482 CRT_CALL_STATIC_FUNCTION (__LIBGCC_INIT_SECTION_ASM_OP__, frame_dummy)
 483 #else /* defined(__LIBGCC_INIT_SECTION_ASM_OP__) */
 484 #if defined(__FDPIC__)
 485 __asm__("\t.equ\t__frame_dummy_alias, frame_dummy\n");
 486 extern char __frame_dummy_alias;
 487 static void *__frame_dummy_init_array_entry[]
 488 __attribute__ ((__used__, section(".init_array"), aligned(sizeof(void *))))
 489      = { &__frame_dummy_alias };
 490 #else /* defined(__FDPIC__) */
 491 static func_ptr __frame_dummy_init_array_entry[]
 492   __attribute__ ((__used__, section(".init_array"),
 493                   aligned(__alignof__(func_ptr)))) = { frame_dummy };
 494 #endif /* defined(__FDPIC__) */
 495 #endif /* !defined(__LIBGCC_INIT_SECTION_ASM_OP__) */
 496 #endif /* USE_EH_FRAME_REGISTRY || USE_TM_CLONE_REGISTRY */
 497
 498 #else  /* OBJECT_FORMAT_ELF */
 499
 500 /* The function __do_global_ctors_aux is compiled twice (once in crtbegin.o
 501    and once in crtend.o).  It must be declared static to avoid a link
 502    error.  Here, we define __do_global_ctors as an externally callable
 503    function.  It is externally callable so that __main can invoke it when
 504    INVOKE__main is defined.  This has the additional effect of forcing cc1
 505    to switch to the .text section.  */
 506
 507 static void __do_global_ctors_aux (void);
 508 void
 509 __do_global_ctors (void)
 510 {
 511 #ifdef INVOKE__main
 512   /* If __main won't actually call __do_global_ctors then it doesn't matter
 513      what's inside the function.  The inside of __do_global_ctors_aux is
 514      called automatically in that case.  And the Alliant fx2800 linker
 515      crashes on this reference.  So prevent the crash.  */
 516   __do_global_ctors_aux ();
 517 #endif
 518 }
 519
 520 asm (__LIBGCC_INIT_SECTION_ASM_OP__);   /* cc1 doesn't know that we are switching! */
 521
 522 /* A routine to invoke all of the global constructors upon entry to the
 523    program.  We put this into the .init section (for systems that have
 524    such a thing) so that we can properly perform the construction of
 525    file-scope static-storage C++ objects within shared libraries.  */
 526
 527 static void __attribute__((used))
 528 __do_global_ctors_aux (void)    /* prologue goes in .init section */
 529 {
 530   FORCE_CODE_SECTION_ALIGN      /* explicit align before switch to .text */
 531   asm (__LIBGCC_TEXT_SECTION_ASM_OP__); /* don't put epilogue and body in .init */
 532   DO_GLOBAL_CTORS_BODY;
 533   atexit (__do_global_dtors);
 534 }
 535
 536 #endif /* OBJECT_FORMAT_ELF */
 537
 538 #elif defined(HAS_INIT_SECTION) /* ! __LIBGCC_INIT_SECTION_ASM_OP__ */
 539
 540 extern void __do_global_dtors (void);
 541
 542 /* This case is used by the Irix 6 port, which supports named sections but
 543    not an SVR4-style .fini section.  __do_global_dtors can be non-static
 544    in this case because we protect it with -hidden_symbol.  */
 545
 546 void
 547 __do_global_dtors (void)
 548 {
 549   func_ptr *p, f;
 550   for (p = __DTOR_LIST__ + 1; (f = *p); p++)
 551     f ();
 552
 553 #if USE_TM_CLONE_REGISTRY
 554   deregister_tm_clones ();
 555 #endif /* USE_TM_CLONE_REGISTRY */
 556
 557 #ifdef USE_EH_FRAME_REGISTRY
 558   if (__deregister_frame_info)
 559     __deregister_frame_info (__EH_FRAME_BEGIN__);
 560 #endif
 561 }
 562
 563 #if defined(USE_EH_FRAME_REGISTRY) \
 564     || defined(USE_TM_CLONE_REGISTRY)
 565 /* A helper function for __do_global_ctors, which is in crtend.o.  Here
 566    in crtbegin.o, we can reference a couple of symbols not visible there.
 567    Plus, since we're before libgcc.a, we have no problems referencing
 568    functions from there.  */
 569 void
 570 __do_global_ctors_1(void)
 571 {
 572 #ifdef USE_EH_FRAME_REGISTRY
 573   static struct object object;
 574   if (__register_frame_info)
 575     __register_frame_info (__EH_FRAME_BEGIN__, &object);
 576 #endif
 577
 578 #if USE_TM_CLONE_REGISTRY
 579   register_tm_clones ();
 580 #endif /* USE_TM_CLONE_REGISTRY */
 581 }
 582 #endif /* USE_EH_FRAME_REGISTRY || USE_TM_CLONE_REGISTRY */
 583
 584 #else /* ! __LIBGCC_INIT_SECTION_ASM_OP__ && ! HAS_INIT_SECTION */
 585 #error "What are you doing with crtstuff.c, then?"
 586 #endif
 587
 588 #elif defined(CRT_END) /* ! CRT_BEGIN */
 589
 590 /* No need for .ctors/.dtors section if linker can place them in
 591    .init_array/.fini_array section.  */
 592 #ifndef USE_INITFINI_ARRAY
 593 /* Put a word containing zero at the end of each of our two lists of function
 594    addresses.  Note that the words defined here go into the .ctors and .dtors
 595    sections of the crtend.o file, and since that file is always linked in
 596    last, these words naturally end up at the very ends of the two lists
 597    contained in these two sections.  */
 598
 599 #ifdef CTOR_LIST_END
 600 CTOR_LIST_END;
 601 #elif defined(__LIBGCC_CTORS_SECTION_ASM_OP__)
 602 /* Hack: force cc1 to switch to .data section early, so that assembling
 603    __CTOR_LIST__ does not undo our behind-the-back change to .ctors.  */
 604 static func_ptr force_to_data[1] __attribute__ ((__used__)) = { };
 605 asm (__LIBGCC_CTORS_SECTION_ASM_OP__);
 606 STATIC func_ptr __CTOR_END__[1]
 607   __attribute__((aligned(__alignof__(func_ptr))))
 608   = { (func_ptr) 0 };
 609 #else
 610 STATIC func_ptr __CTOR_END__[1]
 611   __attribute__((section(".ctors"), aligned(__alignof__(func_ptr))))
 612   = { (func_ptr) 0 };
 613 #endif
 614
 615 #ifdef DTOR_LIST_END
 616 DTOR_LIST_END;
 617 #elif defined(HIDDEN_DTOR_LIST_END)
 618 #ifdef __LIBGCC_DTORS_SECTION_ASM_OP__
 619 asm (__LIBGCC_DTORS_SECTION_ASM_OP__);
 620 #endif
 621 func_ptr __DTOR_END__[1]
 622   __attribute__ ((used,
 623 #ifndef __LIBGCC_DTORS_SECTION_ASM_OP__
 624                   section(".dtors"),
 625 #endif
 626                   aligned(__alignof__(func_ptr)), visibility ("hidden")))
 627   = { (func_ptr) 0 };
 628 #elif defined(__LIBGCC_DTORS_SECTION_ASM_OP__)
 629 asm (__LIBGCC_DTORS_SECTION_ASM_OP__);
 630 STATIC func_ptr __DTOR_END__[1]
 631   __attribute__ ((used, aligned(__alignof__(func_ptr))))
 632   = { (func_ptr) 0 };
 633 #else
 634 STATIC func_ptr __DTOR_END__[1]
 635   __attribute__((used, section(".dtors"), aligned(__alignof__(func_ptr))))
 636   = { (func_ptr) 0 };
 637 #endif
 638 #endif /* USE_INITFINI_ARRAY */
 639
 640 #ifdef __LIBGCC_EH_FRAME_SECTION_NAME__
 641 /* Terminate the frame unwind info section with a 4byte 0 as a sentinel;
 642    this would be the 'length' field in a real FDE.  */
 643 # if __INT_MAX__ == 2147483647
 644 typedef int int32;
 645 # elif __LONG_MAX__ == 2147483647
 646 typedef long int32;
 647 # elif __SHRT_MAX__ == 2147483647
 648 typedef short int32;
 649 # else
 650 #  error "Missing a 4 byte integer"
 651 # endif
 652 STATIC EH_FRAME_SECTION_CONST int32 __FRAME_END__[]
 653      __attribute__ ((used, section(__LIBGCC_EH_FRAME_SECTION_NAME__),
 654                      aligned(__alignof__(int32))))
 655      = { 0 };
 656 #endif /* __LIBGCC_EH_FRAME_SECTION_NAME__ */
 657
 658 #if USE_TM_CLONE_REGISTRY
 659 # ifndef HAVE_GAS_HIDDEN
 660 static
 661 # endif
 662 func_ptr __TMC_END__[]
 663   __attribute__((used, section(".tm_clone_table"),
 664                  aligned(__alignof__(void *))))
 665 # ifdef HAVE_GAS_HIDDEN
 666   __attribute__((__visibility__ ("hidden"))) = { };
 667 # else
 668   = { 0, 0 };
 669 # endif
 670 #endif /* USE_TM_CLONE_REGISTRY */
 671
 672 #ifdef __LIBGCC_INIT_ARRAY_SECTION_ASM_OP__
 673
 674 /* If we are using .init_array, there is nothing to do.  */
 675
 676 #elif defined(__LIBGCC_INIT_SECTION_ASM_OP__)
 677
 678 #ifdef OBJECT_FORMAT_ELF
 679 static void __attribute__((used))
 680 __do_global_ctors_aux (void)
 681 {
 682   func_ptr *p;
 683   for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
 684     (*p) ();
 685 }
 686
 687 /* Stick a call to __do_global_ctors_aux into the .init section.  */
 688 CRT_CALL_STATIC_FUNCTION (__LIBGCC_INIT_SECTION_ASM_OP__, __do_global_ctors_aux)
 689 #else  /* OBJECT_FORMAT_ELF */
 690
 691 /* Stick the real initialization code, followed by a normal sort of
 692    function epilogue at the very end of the .init section for this
 693    entire root executable file or for this entire shared library file.
 694
 695    Note that we use some tricks here to get *just* the body and just
 696    a function epilogue (but no function prologue) into the .init
 697    section of the crtend.o file.  Specifically, we switch to the .text
 698    section, start to define a function, and then we switch to the .init
 699    section just before the body code.
 700
 701    Earlier on, we put the corresponding function prologue into the .init
 702    section of the crtbegin.o file (which will be linked in first).
 703
 704    Note that we want to invoke all constructors for C++ file-scope static-
 705    storage objects AFTER any other possible initialization actions which
 706    may be performed by the code in the .init section contributions made by
 707    other libraries, etc.  That's because those other initializations may
 708    include setup operations for very primitive things (e.g. initializing
 709    the state of the floating-point coprocessor, etc.) which should be done
 710    before we start to execute any of the user's code.  */
 711
 712 static void
 713 __do_global_ctors_aux (void)    /* prologue goes in .text section */
 714 {
 715   asm (__LIBGCC_INIT_SECTION_ASM_OP__);
 716   DO_GLOBAL_CTORS_BODY;
 717   atexit (__do_global_dtors);
 718 }                               /* epilogue and body go in .init section */
 719
 720 FORCE_CODE_SECTION_ALIGN
 721 asm (__LIBGCC_TEXT_SECTION_ASM_OP__);
 722
 723 #endif /* OBJECT_FORMAT_ELF */
 724
 725 #elif defined(HAS_INIT_SECTION) /* ! __LIBGCC_INIT_SECTION_ASM_OP__ */
 726
 727 extern void __do_global_ctors (void);
 728
 729 /* This case is used by the Irix 6 port, which supports named sections but
 730    not an SVR4-style .init section.  __do_global_ctors can be non-static
 731    in this case because we protect it with -hidden_symbol.  */
 732 void
 733 __do_global_ctors (void)
 734 {
 735   func_ptr *p;
 736 #if defined(USE_EH_FRAME_REGISTRY) \
 737     || defined(USE_TM_CLONE_REGISTRY)
 738   __do_global_ctors_1();
 739 #endif
 740   for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
 741     (*p) ();
 742 }
 743
 744 #else /* ! __LIBGCC_INIT_SECTION_ASM_OP__ && ! HAS_INIT_SECTION */
 745 #error "What are you doing with crtstuff.c, then?"
 746 #endif
 747
 748 #else /* ! CRT_BEGIN && ! CRT_END */
 749 #error "One of CRT_BEGIN or CRT_END must be defined."
 750 #endif