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) 1991-2023 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 #elif !defined(USE_TM_CLONE_REGISTRY)
 157 # define USE_TM_CLONE_REGISTRY 0
 158 #endif
 159
 160 /* We do not want to add the weak attribute to the declarations of these
 161    routines in unwind-dw2-fde.h because that will cause the definition of
 162    these symbols to be weak as well.
 163
 164    This exposes a core issue, how to handle creating weak references vs
 165    how to create weak definitions.  Either we have to have the definition
 166    of TARGET_WEAK_ATTRIBUTE be conditional in the shared header files or
 167    have a second declaration if we want a function's references to be weak,
 168    but not its definition.
 169
 170    Making TARGET_WEAK_ATTRIBUTE conditional seems like a good solution until
 171    one thinks about scaling to larger problems -- i.e., the condition under
 172    which TARGET_WEAK_ATTRIBUTE is active will eventually get far too
 173    complicated.
 174
 175    So, we take an approach similar to #pragma weak -- we have a second
 176    declaration for functions that we want to have weak references.
 177
 178    Neither way is particularly good.  */
 179
 180 /* References to __register_frame_info and __deregister_frame_info should
 181    be weak in this file if at all possible.  */
 182 extern void __register_frame_info (const void *, struct object *)
 183                                   TARGET_ATTRIBUTE_WEAK;
 184 extern void __register_frame_info_bases (const void *, struct object *,
 185                                          void *, void *)
 186                                   TARGET_ATTRIBUTE_WEAK;
 187 extern void *__deregister_frame_info (const void *)
 188                                      TARGET_ATTRIBUTE_WEAK;
 189 extern void *__deregister_frame_info_bases (const void *)
 190                                      TARGET_ATTRIBUTE_WEAK;
 191 extern void __do_global_ctors_1 (void);
 192
 193 /* Likewise for transactional memory clone tables.  */
 194 extern void _ITM_registerTMCloneTable (void *, size_t) TARGET_ATTRIBUTE_WEAK;
 195 extern void _ITM_deregisterTMCloneTable (void *) TARGET_ATTRIBUTE_WEAK;
 196
 197 #ifdef OBJECT_FORMAT_ELF
 198
 199 /*  Declare a pointer to void function type.  */
 200 typedef void (*func_ptr) (void);
 201 #define STATIC static
 202
 203 #else  /* OBJECT_FORMAT_ELF */
 204
 205 #include "gbl-ctors.h"
 206
 207 #define STATIC
 208
 209 #endif /* OBJECT_FORMAT_ELF */
 210
 211 #ifdef CRT_BEGIN
 212
 213 /* NOTE:  In order to be able to support SVR4 shared libraries, we arrange
 214    to have one set of symbols { __CTOR_LIST__, __DTOR_LIST__, __CTOR_END__,
 215    __DTOR_END__ } per root executable and also one set of these symbols
 216    per shared library.  So in any given whole process image, we may have
 217    multiple definitions of each of these symbols.  In order to prevent
 218    these definitions from conflicting with one another, and in order to
 219    ensure that the proper lists are used for the initialization/finalization
 220    of each individual shared library (respectively), we give these symbols
 221    only internal (i.e. `static') linkage, and we also make it a point to
 222    refer to only the __CTOR_END__ symbol in crtend.o and the __DTOR_LIST__
 223    symbol in crtbegin.o, where they are defined.  */
 224
 225 /* No need for .ctors/.dtors section if linker can place them in
 226    .init_array/.fini_array section.  */
 227 #ifndef USE_INITFINI_ARRAY
 228 /* The -1 is a flag to __do_global_[cd]tors indicating that this table
 229    does not start with a count of elements.  */
 230 #ifdef CTOR_LIST_BEGIN
 231 CTOR_LIST_BEGIN;
 232 #elif defined(__LIBGCC_CTORS_SECTION_ASM_OP__)
 233 /* Hack: force cc1 to switch to .data section early, so that assembling
 234    __CTOR_LIST__ does not undo our behind-the-back change to .ctors.  */
 235 static func_ptr force_to_data[1] __attribute__ ((__used__)) = { };
 236 asm (__LIBGCC_CTORS_SECTION_ASM_OP__);
 237 STATIC func_ptr __CTOR_LIST__[1]
 238   __attribute__ ((__used__, aligned(__alignof__(func_ptr))))
 239   = { (func_ptr) (-1) };
 240 #else
 241 STATIC func_ptr __CTOR_LIST__[1]
 242   __attribute__ ((__used__, section(".ctors"), aligned(__alignof__(func_ptr))))
 243   = { (func_ptr) (-1) };
 244 #endif /* __CTOR_LIST__ alternatives */
 245
 246 #ifdef DTOR_LIST_BEGIN
 247 DTOR_LIST_BEGIN;
 248 #elif defined(__LIBGCC_DTORS_SECTION_ASM_OP__)
 249 asm (__LIBGCC_DTORS_SECTION_ASM_OP__);
 250 STATIC func_ptr __DTOR_LIST__[1]
 251   __attribute__ ((aligned(__alignof__(func_ptr))))
 252   = { (func_ptr) (-1) };
 253 #else
 254 STATIC func_ptr __DTOR_LIST__[1]
 255   __attribute__((section(".dtors"), aligned(__alignof__(func_ptr))))
 256   = { (func_ptr) (-1) };
 257 #endif /* __DTOR_LIST__ alternatives */
 258 #endif /* USE_INITFINI_ARRAY */
 259
 260 #ifdef USE_EH_FRAME_REGISTRY
 261 /* Stick a label at the beginning of the frame unwind info so we can register
 262    and deregister it with the exception handling library code.  */
 263 STATIC EH_FRAME_SECTION_CONST char __EH_FRAME_BEGIN__[]
 264      __attribute__((section(__LIBGCC_EH_FRAME_SECTION_NAME__),
 265                     aligned(__alignof__ (void *))))
 266      = { };
 267 #endif /* USE_EH_FRAME_REGISTRY */
 268
 269 #if USE_TM_CLONE_REGISTRY
 270 STATIC func_ptr __TMC_LIST__[]
 271   __attribute__((used, section(".tm_clone_table"), aligned(__alignof__(void*))))
 272   = { };
 273 # ifdef HAVE_GAS_HIDDEN
 274 extern func_ptr __TMC_END__[] __attribute__((__visibility__ ("hidden")));
 275 # endif
 276
 277 static inline void
 278 deregister_tm_clones (void)
 279 {
 280   void (*fn) (void *);
 281
 282 #ifdef HAVE_GAS_HIDDEN
 283   func_ptr *end = __TMC_END__;
 284   // Do not optimize the comparison to false.
 285   __asm ("" : "+g" (end));
 286   if (__TMC_LIST__ == end)
 287     return;
 288 #else
 289   if (__TMC_LIST__[0] == NULL)
 290     return;
 291 #endif
 292
 293   fn = _ITM_deregisterTMCloneTable;
 294   __asm ("" : "+r" (fn));
 295   if (fn)
 296     fn (__TMC_LIST__);
 297 }
 298
 299 static inline void
 300 register_tm_clones (void)
 301 {
 302   void (*fn) (void *, size_t);
 303   size_t size;
 304
 305 #ifdef HAVE_GAS_HIDDEN
 306   func_ptr *end = __TMC_END__;
 307   // Do not optimize the comparison to false.
 308   __asm ("" : "+g" (end));
 309   size = (end - __TMC_LIST__) / 2;
 310 #else
 311   for (size = 0; __TMC_LIST__[size * 2] != NULL; size++)
 312     continue;
 313 #endif
 314   if (size == 0)
 315     return;
 316
 317   fn = _ITM_registerTMCloneTable;
 318   __asm ("" : "+r" (fn));
 319   if (fn)
 320     fn (__TMC_LIST__, size);
 321 }
 322 #endif /* USE_TM_CLONE_REGISTRY */
 323
 324 #if defined(__LIBGCC_INIT_SECTION_ASM_OP__) \
 325     || defined(__LIBGCC_INIT_ARRAY_SECTION_ASM_OP__)
 326
 327 #ifdef OBJECT_FORMAT_ELF
 328
 329 #if DEFAULT_USE_CXA_ATEXIT
 330 /* Declare the __dso_handle variable.  It should have a unique value
 331    in every shared-object; in a main program its value is zero.  The
 332    object should in any case be protected.  This means the instance
 333    in one DSO or the main program is not used in another object.  The
 334    dynamic linker takes care of this.
 335    If __cxa_atexit is not being used, __dso_handle will not be used and
 336    doesn't need to be defined.  */
 337
 338 #ifdef TARGET_LIBGCC_SDATA_SECTION
 339 extern void *__dso_handle __attribute__ ((__section__ (TARGET_LIBGCC_SDATA_SECTION)));
 340 #endif
 341 #ifdef HAVE_GAS_HIDDEN
 342 extern void *__dso_handle __attribute__ ((__visibility__ ("hidden")));
 343 #endif
 344 #ifdef CRTSTUFFS_O
 345 void *__dso_handle = &__dso_handle;
 346 #else
 347 void *__dso_handle = 0;
 348 #endif
 349 #endif /* DEFAULT_USE_CXA_ATEXIT */
 350
 351 /* The __cxa_finalize function may not be available so we use only a
 352    weak declaration.  */
 353 extern void __cxa_finalize (void *) TARGET_ATTRIBUTE_WEAK;
 354
 355 /* Run all the global destructors on exit from the program.  */
 356
 357 /* Some systems place the number of pointers in the first word of the
 358    table.  On SVR4 however, that word is -1.  In all cases, the table is
 359    null-terminated.  On SVR4, we start from the beginning of the list and
 360    invoke each per-compilation-unit destructor routine in order
 361    until we find that null.
 362
 363    Note that this function MUST be static.  There will be one of these
 364    functions in each root executable and one in each shared library, but
 365    although they all have the same code, each one is unique in that it
 366    refers to one particular associated `__DTOR_LIST__' which belongs to the
 367    same particular root executable or shared library file.
 368
 369    On some systems, this routine is run more than once from the .fini,
 370    when exit is called recursively, so we arrange to remember where in
 371    the list we left off processing, and we resume at that point,
 372    should we be re-invoked.
 373
 374    This routine does not need to be run if none of the following clauses are
 375    true, as it will not do anything, so can be removed.  */
 376 #if defined(CRTSTUFFS_O) || !defined(FINI_ARRAY_SECTION_ASM_OP) \
 377   || USE_TM_CLONE_REGISTRY || defined(USE_EH_FRAME_REGISTRY)
 378 static void __attribute__((used))
 379 __do_global_dtors_aux (void)
 380 {
 381   static _Bool completed;
 382
 383   if (__builtin_expect (completed, 0))
 384     return;
 385
 386 #if DEFAULT_USE_CXA_ATEXIT
 387 #ifdef CRTSTUFFS_O
 388   if (__cxa_finalize)
 389     __cxa_finalize (__dso_handle);
 390 #endif
 391 #endif
 392
 393 #ifdef FINI_ARRAY_SECTION_ASM_OP
 394   /* If we are using .fini_array then destructors will be run via that
 395      mechanism.  */
 396 #elif defined(HIDDEN_DTOR_LIST_END)
 397   {
 398     /* Safer version that makes sure only .dtors function pointers are
 399        called even if the static variable is maliciously changed.  */
 400     extern func_ptr __DTOR_END__[] __attribute__((visibility ("hidden")));
 401     static size_t dtor_idx;
 402     const size_t max_idx = __DTOR_END__ - __DTOR_LIST__ - 1;
 403     func_ptr *dtor_list;
 404
 405     __asm ("" : "=g" (dtor_list) : "0" (__DTOR_LIST__));
 406     while (dtor_idx < max_idx)
 407       dtor_list[++dtor_idx] ();
 408   }
 409 #else /* !defined (FINI_ARRAY_SECTION_ASM_OP) */
 410   {
 411     static func_ptr *p = __DTOR_LIST__ + 1;
 412     func_ptr f;
 413
 414     while ((f = *p))
 415       {
 416         p++;
 417         f ();
 418       }
 419   }
 420 #endif /* !defined(FINI_ARRAY_SECTION_ASM_OP) */
 421
 422 #if USE_TM_CLONE_REGISTRY
 423   deregister_tm_clones ();
 424 #endif /* USE_TM_CLONE_REGISTRY */
 425
 426 #ifdef USE_EH_FRAME_REGISTRY
 427 #ifdef CRT_GET_RFIB_DATA
 428   /* If we used the new __register_frame_info_bases interface,
 429      make sure that we deregister from the same place.  */
 430   if (__deregister_frame_info_bases)
 431     __deregister_frame_info_bases (__EH_FRAME_BEGIN__);
 432 #else
 433   if (__deregister_frame_info)
 434     __deregister_frame_info (__EH_FRAME_BEGIN__);
 435 #endif
 436 #endif
 437
 438   completed = 1;
 439 }
 440
 441 /* Stick a call to __do_global_dtors_aux into the .fini section.  */
 442 #ifdef FINI_SECTION_ASM_OP
 443 CRT_CALL_STATIC_FUNCTION (FINI_SECTION_ASM_OP, __do_global_dtors_aux)
 444 #elif defined (FINI_ARRAY_SECTION_ASM_OP)
 445 #if defined(__FDPIC__)
 446 __asm__("\t.equ\t__do_global_dtors_aux_alias, __do_global_dtors_aux\n");
 447 extern char __do_global_dtors_aux_alias;
 448 static void *__do_global_dtors_aux_fini_array_entry[]
 449 __attribute__ ((__used__, section(".fini_array"), aligned(sizeof(void *))))
 450      = { &__do_global_dtors_aux_alias };
 451 #else /* defined(__FDPIC__) */
 452 static func_ptr __do_global_dtors_aux_fini_array_entry[]
 453   __attribute__ ((__used__, section(".fini_array"),
 454                   aligned(__alignof__(func_ptr)))) = { __do_global_dtors_aux };
 455 #endif /* defined(__FDPIC__) */
 456 #else /* !FINI_SECTION_ASM_OP && !FINI_ARRAY_SECTION_ASM_OP */
 457 static void __attribute__((used))
 458 __do_global_dtors_aux_1 (void)
 459 {
 460   atexit (__do_global_dtors_aux);
 461 }
 462 CRT_CALL_STATIC_FUNCTION (__LIBGCC_INIT_SECTION_ASM_OP__,
 463                           __do_global_dtors_aux_1)
 464 #endif
 465 #endif /* defined(CRTSTUFFS_O) || !defined(FINI_ARRAY_SECTION_ASM_OP)
 466   || USE_TM_CLONE_REGISTRY || defined(USE_EH_FRAME_REGISTRY) */
 467
 468 #if defined(USE_EH_FRAME_REGISTRY) || USE_TM_CLONE_REGISTRY
 469 /* Stick a call to __register_frame_info into the .init section.  For some
 470    reason calls with no arguments work more reliably in .init, so stick the
 471    call in another function.  */
 472
 473 static void __attribute__((used))
 474 frame_dummy (void)
 475 {
 476 #ifdef USE_EH_FRAME_REGISTRY
 477   static struct object object;
 478 #ifdef CRT_GET_RFIB_DATA
 479   void *tbase, *dbase;
 480   tbase = 0;
 481   CRT_GET_RFIB_DATA (dbase);
 482   if (__register_frame_info_bases)
 483     __register_frame_info_bases (__EH_FRAME_BEGIN__, &object, tbase, dbase);
 484 #else
 485   if (__register_frame_info)
 486     __register_frame_info (__EH_FRAME_BEGIN__, &object);
 487 #endif /* CRT_GET_RFIB_DATA */
 488 #endif /* USE_EH_FRAME_REGISTRY */
 489
 490 #if USE_TM_CLONE_REGISTRY
 491   register_tm_clones ();
 492 #endif /* USE_TM_CLONE_REGISTRY */
 493 }
 494
 495 #ifdef __LIBGCC_INIT_SECTION_ASM_OP__
 496 CRT_CALL_STATIC_FUNCTION (__LIBGCC_INIT_SECTION_ASM_OP__, frame_dummy)
 497 #else /* defined(__LIBGCC_INIT_SECTION_ASM_OP__) */
 498 #if defined(__FDPIC__)
 499 __asm__("\t.equ\t__frame_dummy_alias, frame_dummy\n");
 500 extern char __frame_dummy_alias;
 501 static void *__frame_dummy_init_array_entry[]
 502 __attribute__ ((__used__, section(".init_array"), aligned(sizeof(void *))))
 503      = { &__frame_dummy_alias };
 504 #else /* defined(__FDPIC__) */
 505 static func_ptr __frame_dummy_init_array_entry[]
 506   __attribute__ ((__used__, section(".init_array"),
 507                   aligned(__alignof__(func_ptr)))) = { frame_dummy };
 508 #endif /* defined(__FDPIC__) */
 509 #endif /* !defined(__LIBGCC_INIT_SECTION_ASM_OP__) */
 510 #endif /* USE_EH_FRAME_REGISTRY || USE_TM_CLONE_REGISTRY */
 511
 512 #else  /* OBJECT_FORMAT_ELF */
 513
 514 /* The function __do_global_ctors_aux is compiled twice (once in crtbegin.o
 515    and once in crtend.o).  It must be declared static to avoid a link
 516    error.  Here, we define __do_global_ctors as an externally callable
 517    function.  It is externally callable so that __main can invoke it when
 518    INVOKE__main is defined.  This has the additional effect of forcing cc1
 519    to switch to the .text section.  */
 520
 521 static void __do_global_ctors_aux (void);
 522 void
 523 __do_global_ctors (void)
 524 {
 525 #ifdef INVOKE__main
 526   /* If __main won't actually call __do_global_ctors then it doesn't matter
 527      what's inside the function.  The inside of __do_global_ctors_aux is
 528      called automatically in that case.  And the Alliant fx2800 linker
 529      crashes on this reference.  So prevent the crash.  */
 530   __do_global_ctors_aux ();
 531 #endif
 532 }
 533
 534 asm (__LIBGCC_INIT_SECTION_ASM_OP__);   /* cc1 doesn't know that we are switching! */
 535
 536 /* A routine to invoke all of the global constructors upon entry to the
 537    program.  We put this into the .init section (for systems that have
 538    such a thing) so that we can properly perform the construction of
 539    file-scope static-storage C++ objects within shared libraries.  */
 540
 541 static void __attribute__((used))
 542 __do_global_ctors_aux (void)    /* prologue goes in .init section */
 543 {
 544   FORCE_CODE_SECTION_ALIGN      /* explicit align before switch to .text */
 545   asm (__LIBGCC_TEXT_SECTION_ASM_OP__); /* don't put epilogue and body in .init */
 546   DO_GLOBAL_CTORS_BODY;
 547   atexit (__do_global_dtors);
 548 }
 549
 550 #endif /* OBJECT_FORMAT_ELF */
 551
 552 #elif defined(HAS_INIT_SECTION) /* ! __LIBGCC_INIT_SECTION_ASM_OP__ */
 553
 554 extern void __do_global_dtors (void);
 555
 556 /* This case is used by the Irix 6 port, which supports named sections but
 557    not an SVR4-style .fini section.  __do_global_dtors can be non-static
 558    in this case because we protect it with -hidden_symbol.  */
 559
 560 void
 561 __do_global_dtors (void)
 562 {
 563   func_ptr *p, f;
 564   for (p = __DTOR_LIST__ + 1; (f = *p); p++)
 565     f ();
 566
 567 #if USE_TM_CLONE_REGISTRY
 568   deregister_tm_clones ();
 569 #endif /* USE_TM_CLONE_REGISTRY */
 570
 571 #ifdef USE_EH_FRAME_REGISTRY
 572   if (__deregister_frame_info)
 573     __deregister_frame_info (__EH_FRAME_BEGIN__);
 574 #endif
 575 }
 576
 577 #if defined(USE_EH_FRAME_REGISTRY) || USE_TM_CLONE_REGISTRY
 578 /* A helper function for __do_global_ctors, which is in crtend.o.  Here
 579    in crtbegin.o, we can reference a couple of symbols not visible there.
 580    Plus, since we're before libgcc.a, we have no problems referencing
 581    functions from there.  */
 582 void
 583 __do_global_ctors_1(void)
 584 {
 585 #ifdef USE_EH_FRAME_REGISTRY
 586   static struct object object;
 587   if (__register_frame_info)
 588     __register_frame_info (__EH_FRAME_BEGIN__, &object);
 589 #endif
 590
 591 #if USE_TM_CLONE_REGISTRY
 592   register_tm_clones ();
 593 #endif /* USE_TM_CLONE_REGISTRY */
 594 }
 595 #endif /* USE_EH_FRAME_REGISTRY || USE_TM_CLONE_REGISTRY */
 596
 597 #else /* ! __LIBGCC_INIT_SECTION_ASM_OP__ && ! HAS_INIT_SECTION */
 598 #error "What are you doing with crtstuff.c, then?"
 599 #endif
 600
 601 #elif defined(CRT_END) /* ! CRT_BEGIN */
 602
 603 /* No need for .ctors/.dtors section if linker can place them in
 604    .init_array/.fini_array section.  */
 605 #ifndef USE_INITFINI_ARRAY
 606 /* Put a word containing zero at the end of each of our two lists of function
 607    addresses.  Note that the words defined here go into the .ctors and .dtors
 608    sections of the crtend.o file, and since that file is always linked in
 609    last, these words naturally end up at the very ends of the two lists
 610    contained in these two sections.  */
 611
 612 #ifdef CTOR_LIST_END
 613 CTOR_LIST_END;
 614 #elif defined(__LIBGCC_CTORS_SECTION_ASM_OP__)
 615 /* Hack: force cc1 to switch to .data section early, so that assembling
 616    __CTOR_LIST__ does not undo our behind-the-back change to .ctors.  */
 617 static func_ptr force_to_data[1] __attribute__ ((__used__)) = { };
 618 asm (__LIBGCC_CTORS_SECTION_ASM_OP__);
 619 STATIC func_ptr __CTOR_END__[1]
 620   __attribute__((aligned(__alignof__(func_ptr))))
 621   = { (func_ptr) 0 };
 622 #else
 623 STATIC func_ptr __CTOR_END__[1]
 624   __attribute__((section(".ctors"), aligned(__alignof__(func_ptr))))
 625   = { (func_ptr) 0 };
 626 #endif
 627
 628 #ifdef DTOR_LIST_END
 629 DTOR_LIST_END;
 630 #elif defined(HIDDEN_DTOR_LIST_END)
 631 #ifdef __LIBGCC_DTORS_SECTION_ASM_OP__
 632 asm (__LIBGCC_DTORS_SECTION_ASM_OP__);
 633 #endif
 634 func_ptr __DTOR_END__[1]
 635   __attribute__ ((used,
 636 #ifndef __LIBGCC_DTORS_SECTION_ASM_OP__
 637                   section(".dtors"),
 638 #endif
 639                   aligned(__alignof__(func_ptr)), visibility ("hidden")))
 640   = { (func_ptr) 0 };
 641 #elif defined(__LIBGCC_DTORS_SECTION_ASM_OP__)
 642 asm (__LIBGCC_DTORS_SECTION_ASM_OP__);
 643 STATIC func_ptr __DTOR_END__[1]
 644   __attribute__ ((used, aligned(__alignof__(func_ptr))))
 645   = { (func_ptr) 0 };
 646 #else
 647 STATIC func_ptr __DTOR_END__[1]
 648   __attribute__((used, section(".dtors"), aligned(__alignof__(func_ptr))))
 649   = { (func_ptr) 0 };
 650 #endif
 651 #endif /* USE_INITFINI_ARRAY */
 652
 653 #ifdef __LIBGCC_EH_FRAME_SECTION_NAME__
 654 /* Terminate the frame unwind info section with a 4byte 0 as a sentinel;
 655    this would be the 'length' field in a real FDE.  */
 656 # if __INT_MAX__ == 2147483647
 657 typedef int int32;
 658 # elif __LONG_MAX__ == 2147483647
 659 typedef long int32;
 660 # elif __SHRT_MAX__ == 2147483647
 661 typedef short int32;
 662 # else
 663 #  error "Missing a 4 byte integer"
 664 # endif
 665 STATIC EH_FRAME_SECTION_CONST int32 __FRAME_END__[]
 666      __attribute__ ((used, section(__LIBGCC_EH_FRAME_SECTION_NAME__),
 667                      aligned(__alignof__(int32))))
 668      = { 0 };
 669 #endif /* __LIBGCC_EH_FRAME_SECTION_NAME__ */
 670
 671 #if USE_TM_CLONE_REGISTRY
 672 # ifndef HAVE_GAS_HIDDEN
 673 static
 674 # endif
 675 func_ptr __TMC_END__[]
 676   __attribute__((used, section(".tm_clone_table"),
 677                  aligned(__alignof__(void *))))
 678 # ifdef HAVE_GAS_HIDDEN
 679   __attribute__((__visibility__ ("hidden"))) = { };
 680 # else
 681   = { 0, 0 };
 682 # endif
 683 #endif /* USE_TM_CLONE_REGISTRY */
 684
 685 #ifdef __LIBGCC_INIT_ARRAY_SECTION_ASM_OP__
 686
 687 /* If we are using .init_array, there is nothing to do.  */
 688
 689 #elif defined(__LIBGCC_INIT_SECTION_ASM_OP__)
 690
 691 #ifdef OBJECT_FORMAT_ELF
 692 static void __attribute__((used))
 693 __do_global_ctors_aux (void)
 694 {
 695   func_ptr *p;
 696   for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
 697     (*p) ();
 698 }
 699
 700 /* Stick a call to __do_global_ctors_aux into the .init section.  */
 701 CRT_CALL_STATIC_FUNCTION (__LIBGCC_INIT_SECTION_ASM_OP__, __do_global_ctors_aux)
 702 #else  /* OBJECT_FORMAT_ELF */
 703
 704 /* Stick the real initialization code, followed by a normal sort of
 705    function epilogue at the very end of the .init section for this
 706    entire root executable file or for this entire shared library file.
 707
 708    Note that we use some tricks here to get *just* the body and just
 709    a function epilogue (but no function prologue) into the .init
 710    section of the crtend.o file.  Specifically, we switch to the .text
 711    section, start to define a function, and then we switch to the .init
 712    section just before the body code.
 713
 714    Earlier on, we put the corresponding function prologue into the .init
 715    section of the crtbegin.o file (which will be linked in first).
 716
 717    Note that we want to invoke all constructors for C++ file-scope static-
 718    storage objects AFTER any other possible initialization actions which
 719    may be performed by the code in the .init section contributions made by
 720    other libraries, etc.  That's because those other initializations may
 721    include setup operations for very primitive things (e.g. initializing
 722    the state of the floating-point coprocessor, etc.) which should be done
 723    before we start to execute any of the user's code.  */
 724
 725 static void
 726 __do_global_ctors_aux (void)    /* prologue goes in .text section */
 727 {
 728   asm (__LIBGCC_INIT_SECTION_ASM_OP__);
 729   DO_GLOBAL_CTORS_BODY;
 730   atexit (__do_global_dtors);
 731 }                               /* epilogue and body go in .init section */
 732
 733 FORCE_CODE_SECTION_ALIGN
 734 asm (__LIBGCC_TEXT_SECTION_ASM_OP__);
 735
 736 #endif /* OBJECT_FORMAT_ELF */
 737
 738 #elif defined(HAS_INIT_SECTION) /* ! __LIBGCC_INIT_SECTION_ASM_OP__ */
 739
 740 extern void __do_global_ctors (void);
 741
 742 /* This case is used by the Irix 6 port, which supports named sections but
 743    not an SVR4-style .init section.  __do_global_ctors can be non-static
 744    in this case because we protect it with -hidden_symbol.  */
 745 void
 746 __do_global_ctors (void)
 747 {
 748   func_ptr *p;
 749 #if defined(USE_EH_FRAME_REGISTRY) || USE_TM_CLONE_REGISTRY
 750   __do_global_ctors_1();
 751 #endif
 752   for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
 753     (*p) ();
 754 }
 755
 756 #else /* ! __LIBGCC_INIT_SECTION_ASM_OP__ && ! HAS_INIT_SECTION */
 757 #error "What are you doing with crtstuff.c, then?"
 758 #endif
 759
 760 #else /* ! CRT_BEGIN && ! CRT_END */
 761 #error "One of CRT_BEGIN or CRT_END must be defined."
 762 #endif