xref: /dragonfly/contrib/gcc-8.0/libgcc/crtstuff.c (revision 3d33658b)
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 _Jv_RegisterClasses.  */
192 extern void _Jv_RegisterClasses (void *) TARGET_ATTRIBUTE_WEAK;
193 
194 /* Likewise for transactional memory clone tables.  */
195 extern void _ITM_registerTMCloneTable (void *, size_t) TARGET_ATTRIBUTE_WEAK;
196 extern void _ITM_deregisterTMCloneTable (void *) TARGET_ATTRIBUTE_WEAK;
197 
198 #ifdef OBJECT_FORMAT_ELF
199 
200 /*  Declare a pointer to void function type.  */
201 typedef void (*func_ptr) (void);
202 #define STATIC static
203 
204 #else  /* OBJECT_FORMAT_ELF */
205 
206 #include "gbl-ctors.h"
207 
208 #define STATIC
209 
210 #endif /* OBJECT_FORMAT_ELF */
211 
212 #ifdef CRT_BEGIN
213 
214 /* NOTE:  In order to be able to support SVR4 shared libraries, we arrange
215    to have one set of symbols { __CTOR_LIST__, __DTOR_LIST__, __CTOR_END__,
216    __DTOR_END__ } per root executable and also one set of these symbols
217    per shared library.  So in any given whole process image, we may have
218    multiple definitions of each of these symbols.  In order to prevent
219    these definitions from conflicting with one another, and in order to
220    ensure that the proper lists are used for the initialization/finalization
221    of each individual shared library (respectively), we give these symbols
222    only internal (i.e. `static') linkage, and we also make it a point to
223    refer to only the __CTOR_END__ symbol in crtend.o and the __DTOR_LIST__
224    symbol in crtbegin.o, where they are defined.  */
225 
226 /* No need for .ctors/.dtors section if linker can place them in
227    .init_array/.fini_array section.  */
228 #ifndef USE_INITFINI_ARRAY
229 /* The -1 is a flag to __do_global_[cd]tors indicating that this table
230    does not start with a count of elements.  */
231 #ifdef CTOR_LIST_BEGIN
232 CTOR_LIST_BEGIN;
233 #elif defined(__LIBGCC_CTORS_SECTION_ASM_OP__)
234 /* Hack: force cc1 to switch to .data section early, so that assembling
235    __CTOR_LIST__ does not undo our behind-the-back change to .ctors.  */
236 static func_ptr force_to_data[1] __attribute__ ((__used__)) = { };
237 asm (__LIBGCC_CTORS_SECTION_ASM_OP__);
238 STATIC func_ptr __CTOR_LIST__[1]
239   __attribute__ ((__used__, aligned(sizeof(func_ptr))))
240   = { (func_ptr) (-1) };
241 #else
242 STATIC func_ptr __CTOR_LIST__[1]
243   __attribute__ ((__used__, section(".ctors"), aligned(sizeof(func_ptr))))
244   = { (func_ptr) (-1) };
245 #endif /* __CTOR_LIST__ alternatives */
246 
247 #ifdef DTOR_LIST_BEGIN
248 DTOR_LIST_BEGIN;
249 #elif defined(__LIBGCC_DTORS_SECTION_ASM_OP__)
250 asm (__LIBGCC_DTORS_SECTION_ASM_OP__);
251 STATIC func_ptr __DTOR_LIST__[1]
252   __attribute__ ((aligned(sizeof(func_ptr))))
253   = { (func_ptr) (-1) };
254 #else
255 STATIC func_ptr __DTOR_LIST__[1]
256   __attribute__((section(".dtors"), aligned(sizeof(func_ptr))))
257   = { (func_ptr) (-1) };
258 #endif /* __DTOR_LIST__ alternatives */
259 #endif /* USE_INITFINI_ARRAY */
260 
261 #ifdef USE_EH_FRAME_REGISTRY
262 /* Stick a label at the beginning of the frame unwind info so we can register
263    and deregister it with the exception handling library code.  */
264 STATIC EH_FRAME_SECTION_CONST char __EH_FRAME_BEGIN__[]
265      __attribute__((section(__LIBGCC_EH_FRAME_SECTION_NAME__), aligned(4)))
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(sizeof(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 /* Declare the __dso_handle variable.  It should have a unique value
330    in every shared-object; in a main program its value is zero.  The
331    object should in any case be protected.  This means the instance
332    in one DSO or the main program is not used in another object.  The
333    dynamic linker takes care of this.  */
334 
335 #ifdef TARGET_LIBGCC_SDATA_SECTION
336 extern void *__dso_handle __attribute__ ((__section__ (TARGET_LIBGCC_SDATA_SECTION)));
337 #endif
338 #ifdef HAVE_GAS_HIDDEN
339 extern void *__dso_handle __attribute__ ((__visibility__ ("hidden")));
340 #endif
341 #ifdef CRTSTUFFS_O
342 void *__dso_handle = &__dso_handle;
343 #else
344 void *__dso_handle = 0;
345 #endif
346 
347 /* The __cxa_finalize function may not be available so we use only a
348    weak declaration.  */
349 extern void __cxa_finalize (void *) TARGET_ATTRIBUTE_WEAK;
350 
351 /* Run all the global destructors on exit from the program.  */
352 
353 /* Some systems place the number of pointers in the first word of the
354    table.  On SVR4 however, that word is -1.  In all cases, the table is
355    null-terminated.  On SVR4, we start from the beginning of the list and
356    invoke each per-compilation-unit destructor routine in order
357    until we find that null.
358 
359    Note that this function MUST be static.  There will be one of these
360    functions in each root executable and one in each shared library, but
361    although they all have the same code, each one is unique in that it
362    refers to one particular associated `__DTOR_LIST__' which belongs to the
363    same particular root executable or shared library file.
364 
365    On some systems, this routine is run more than once from the .fini,
366    when exit is called recursively, so we arrange to remember where in
367    the list we left off processing, and we resume at that point,
368    should we be re-invoked.  */
369 
370 static void __attribute__((used))
371 __do_global_dtors_aux (void)
372 {
373   static _Bool completed;
374 
375   if (__builtin_expect (completed, 0))
376     return;
377 
378 #ifdef CRTSTUFFS_O
379   if (__cxa_finalize)
380     __cxa_finalize (__dso_handle);
381 #endif
382 
383 #ifdef FINI_ARRAY_SECTION_ASM_OP
384   /* If we are using .fini_array then destructors will be run via that
385      mechanism.  */
386 #elif defined(HIDDEN_DTOR_LIST_END)
387   {
388     /* Safer version that makes sure only .dtors function pointers are
389        called even if the static variable is maliciously changed.  */
390     extern func_ptr __DTOR_END__[] __attribute__((visibility ("hidden")));
391     static size_t dtor_idx;
392     const size_t max_idx = __DTOR_END__ - __DTOR_LIST__ - 1;
393     func_ptr *dtor_list;
394 
395     __asm ("" : "=g" (dtor_list) : "0" (__DTOR_LIST__));
396     while (dtor_idx < max_idx)
397       dtor_list[++dtor_idx] ();
398   }
399 #else /* !defined (FINI_ARRAY_SECTION_ASM_OP) */
400   {
401     static func_ptr *p = __DTOR_LIST__ + 1;
402     func_ptr f;
403 
404     while ((f = *p))
405       {
406 	p++;
407 	f ();
408       }
409   }
410 #endif /* !defined(FINI_ARRAY_SECTION_ASM_OP) */
411 
412 #if USE_TM_CLONE_REGISTRY
413   deregister_tm_clones ();
414 #endif /* USE_TM_CLONE_REGISTRY */
415 
416 #ifdef USE_EH_FRAME_REGISTRY
417 #ifdef CRT_GET_RFIB_DATA
418   /* If we used the new __register_frame_info_bases interface,
419      make sure that we deregister from the same place.  */
420   if (__deregister_frame_info_bases)
421     __deregister_frame_info_bases (__EH_FRAME_BEGIN__);
422 #else
423   if (__deregister_frame_info)
424     __deregister_frame_info (__EH_FRAME_BEGIN__);
425 #endif
426 #endif
427 
428   completed = 1;
429 }
430 
431 /* Stick a call to __do_global_dtors_aux into the .fini section.  */
432 #ifdef FINI_SECTION_ASM_OP
433 CRT_CALL_STATIC_FUNCTION (FINI_SECTION_ASM_OP, __do_global_dtors_aux)
434 #elif defined (FINI_ARRAY_SECTION_ASM_OP)
435 static func_ptr __do_global_dtors_aux_fini_array_entry[]
436   __attribute__ ((__used__, section(".fini_array"), aligned(sizeof(func_ptr))))
437   = { __do_global_dtors_aux };
438 #else /* !FINI_SECTION_ASM_OP && !FINI_ARRAY_SECTION_ASM_OP */
439 static void __attribute__((used))
440 __do_global_dtors_aux_1 (void)
441 {
442   atexit (__do_global_dtors_aux);
443 }
444 CRT_CALL_STATIC_FUNCTION (__LIBGCC_INIT_SECTION_ASM_OP__,
445 			  __do_global_dtors_aux_1)
446 #endif
447 
448 #if defined(USE_EH_FRAME_REGISTRY) \
449     || defined(USE_TM_CLONE_REGISTRY)
450 /* Stick a call to __register_frame_info into the .init section.  For some
451    reason calls with no arguments work more reliably in .init, so stick the
452    call in another function.  */
453 
454 static void __attribute__((used))
455 frame_dummy (void)
456 {
457 #ifdef USE_EH_FRAME_REGISTRY
458   static struct object object;
459 #ifdef CRT_GET_RFIB_DATA
460   void *tbase, *dbase;
461   tbase = 0;
462   CRT_GET_RFIB_DATA (dbase);
463   if (__register_frame_info_bases)
464     __register_frame_info_bases (__EH_FRAME_BEGIN__, &object, tbase, dbase);
465 #else
466   if (__register_frame_info)
467     __register_frame_info (__EH_FRAME_BEGIN__, &object);
468 #endif /* CRT_GET_RFIB_DATA */
469 #endif /* USE_EH_FRAME_REGISTRY */
470 
471 #if USE_TM_CLONE_REGISTRY
472   register_tm_clones ();
473 #endif /* USE_TM_CLONE_REGISTRY */
474 }
475 
476 #ifdef __LIBGCC_INIT_SECTION_ASM_OP__
477 CRT_CALL_STATIC_FUNCTION (__LIBGCC_INIT_SECTION_ASM_OP__, frame_dummy)
478 #else /* defined(__LIBGCC_INIT_SECTION_ASM_OP__) */
479 static func_ptr __frame_dummy_init_array_entry[]
480   __attribute__ ((__used__, section(".init_array"), aligned(sizeof(func_ptr))))
481   = { frame_dummy };
482 #endif /* !defined(__LIBGCC_INIT_SECTION_ASM_OP__) */
483 #endif /* USE_EH_FRAME_REGISTRY || USE_TM_CLONE_REGISTRY */
484 
485 #else  /* OBJECT_FORMAT_ELF */
486 
487 /* The function __do_global_ctors_aux is compiled twice (once in crtbegin.o
488    and once in crtend.o).  It must be declared static to avoid a link
489    error.  Here, we define __do_global_ctors as an externally callable
490    function.  It is externally callable so that __main can invoke it when
491    INVOKE__main is defined.  This has the additional effect of forcing cc1
492    to switch to the .text section.  */
493 
494 static void __do_global_ctors_aux (void);
495 void
496 __do_global_ctors (void)
497 {
498 #ifdef INVOKE__main
499   /* If __main won't actually call __do_global_ctors then it doesn't matter
500      what's inside the function.  The inside of __do_global_ctors_aux is
501      called automatically in that case.  And the Alliant fx2800 linker
502      crashes on this reference.  So prevent the crash.  */
503   __do_global_ctors_aux ();
504 #endif
505 }
506 
507 asm (__LIBGCC_INIT_SECTION_ASM_OP__);	/* cc1 doesn't know that we are switching! */
508 
509 /* A routine to invoke all of the global constructors upon entry to the
510    program.  We put this into the .init section (for systems that have
511    such a thing) so that we can properly perform the construction of
512    file-scope static-storage C++ objects within shared libraries.  */
513 
514 static void __attribute__((used))
515 __do_global_ctors_aux (void)	/* prologue goes in .init section */
516 {
517   FORCE_CODE_SECTION_ALIGN	/* explicit align before switch to .text */
518   asm (__LIBGCC_TEXT_SECTION_ASM_OP__);	/* don't put epilogue and body in .init */
519   DO_GLOBAL_CTORS_BODY;
520   atexit (__do_global_dtors);
521 }
522 
523 #endif /* OBJECT_FORMAT_ELF */
524 
525 #elif defined(HAS_INIT_SECTION) /* ! __LIBGCC_INIT_SECTION_ASM_OP__ */
526 
527 extern void __do_global_dtors (void);
528 
529 /* This case is used by the Irix 6 port, which supports named sections but
530    not an SVR4-style .fini section.  __do_global_dtors can be non-static
531    in this case because we protect it with -hidden_symbol.  */
532 
533 void
534 __do_global_dtors (void)
535 {
536   func_ptr *p, f;
537   for (p = __DTOR_LIST__ + 1; (f = *p); p++)
538     f ();
539 
540 #if USE_TM_CLONE_REGISTRY
541   deregister_tm_clones ();
542 #endif /* USE_TM_CLONE_REGISTRY */
543 
544 #ifdef USE_EH_FRAME_REGISTRY
545   if (__deregister_frame_info)
546     __deregister_frame_info (__EH_FRAME_BEGIN__);
547 #endif
548 }
549 
550 #if defined(USE_EH_FRAME_REGISTRY) \
551     || defined(USE_TM_CLONE_REGISTRY)
552 /* A helper function for __do_global_ctors, which is in crtend.o.  Here
553    in crtbegin.o, we can reference a couple of symbols not visible there.
554    Plus, since we're before libgcc.a, we have no problems referencing
555    functions from there.  */
556 void
557 __do_global_ctors_1(void)
558 {
559 #ifdef USE_EH_FRAME_REGISTRY
560   static struct object object;
561   if (__register_frame_info)
562     __register_frame_info (__EH_FRAME_BEGIN__, &object);
563 #endif
564 
565 #if USE_TM_CLONE_REGISTRY
566   register_tm_clones ();
567 #endif /* USE_TM_CLONE_REGISTRY */
568 }
569 #endif /* USE_EH_FRAME_REGISTRY || USE_TM_CLONE_REGISTRY */
570 
571 #else /* ! __LIBGCC_INIT_SECTION_ASM_OP__ && ! HAS_INIT_SECTION */
572 #error "What are you doing with crtstuff.c, then?"
573 #endif
574 
575 #elif defined(CRT_END) /* ! CRT_BEGIN */
576 
577 /* No need for .ctors/.dtors section if linker can place them in
578    .init_array/.fini_array section.  */
579 #ifndef USE_INITFINI_ARRAY
580 /* Put a word containing zero at the end of each of our two lists of function
581    addresses.  Note that the words defined here go into the .ctors and .dtors
582    sections of the crtend.o file, and since that file is always linked in
583    last, these words naturally end up at the very ends of the two lists
584    contained in these two sections.  */
585 
586 #ifdef CTOR_LIST_END
587 CTOR_LIST_END;
588 #elif defined(__LIBGCC_CTORS_SECTION_ASM_OP__)
589 /* Hack: force cc1 to switch to .data section early, so that assembling
590    __CTOR_LIST__ does not undo our behind-the-back change to .ctors.  */
591 static func_ptr force_to_data[1] __attribute__ ((__used__)) = { };
592 asm (__LIBGCC_CTORS_SECTION_ASM_OP__);
593 STATIC func_ptr __CTOR_END__[1]
594   __attribute__((aligned(sizeof(func_ptr))))
595   = { (func_ptr) 0 };
596 #else
597 STATIC func_ptr __CTOR_END__[1]
598   __attribute__((section(".ctors"), aligned(sizeof(func_ptr))))
599   = { (func_ptr) 0 };
600 #endif
601 
602 #ifdef DTOR_LIST_END
603 DTOR_LIST_END;
604 #elif defined(HIDDEN_DTOR_LIST_END)
605 #ifdef __LIBGCC_DTORS_SECTION_ASM_OP__
606 asm (__LIBGCC_DTORS_SECTION_ASM_OP__);
607 #endif
608 func_ptr __DTOR_END__[1]
609   __attribute__ ((used,
610 #ifndef __LIBGCC_DTORS_SECTION_ASM_OP__
611 		  section(".dtors"),
612 #endif
613 		  aligned(sizeof(func_ptr)), visibility ("hidden")))
614   = { (func_ptr) 0 };
615 #elif defined(__LIBGCC_DTORS_SECTION_ASM_OP__)
616 asm (__LIBGCC_DTORS_SECTION_ASM_OP__);
617 STATIC func_ptr __DTOR_END__[1]
618   __attribute__ ((used, aligned(sizeof(func_ptr))))
619   = { (func_ptr) 0 };
620 #else
621 STATIC func_ptr __DTOR_END__[1]
622   __attribute__((used, section(".dtors"), aligned(sizeof(func_ptr))))
623   = { (func_ptr) 0 };
624 #endif
625 #endif /* USE_INITFINI_ARRAY */
626 
627 #ifdef __LIBGCC_EH_FRAME_SECTION_NAME__
628 /* Terminate the frame unwind info section with a 4byte 0 as a sentinel;
629    this would be the 'length' field in a real FDE.  */
630 # if __INT_MAX__ == 2147483647
631 typedef int int32;
632 # elif __LONG_MAX__ == 2147483647
633 typedef long int32;
634 # elif __SHRT_MAX__ == 2147483647
635 typedef short int32;
636 # else
637 #  error "Missing a 4 byte integer"
638 # endif
639 STATIC EH_FRAME_SECTION_CONST int32 __FRAME_END__[]
640      __attribute__ ((used, section(__LIBGCC_EH_FRAME_SECTION_NAME__),
641 		     aligned(sizeof(int32))))
642      = { 0 };
643 #endif /* __LIBGCC_EH_FRAME_SECTION_NAME__ */
644 
645 #if USE_TM_CLONE_REGISTRY
646 # ifndef HAVE_GAS_HIDDEN
647 static
648 # endif
649 func_ptr __TMC_END__[]
650   __attribute__((used, section(".tm_clone_table"), aligned(sizeof(void *))))
651 # ifdef HAVE_GAS_HIDDEN
652   __attribute__((__visibility__ ("hidden"))) = { };
653 # else
654   = { 0, 0 };
655 # endif
656 #endif /* USE_TM_CLONE_REGISTRY */
657 
658 #ifdef __LIBGCC_INIT_ARRAY_SECTION_ASM_OP__
659 
660 /* If we are using .init_array, there is nothing to do.  */
661 
662 #elif defined(__LIBGCC_INIT_SECTION_ASM_OP__)
663 
664 #ifdef OBJECT_FORMAT_ELF
665 static void __attribute__((used))
666 __do_global_ctors_aux (void)
667 {
668   func_ptr *p;
669   for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
670     (*p) ();
671 }
672 
673 /* Stick a call to __do_global_ctors_aux into the .init section.  */
674 CRT_CALL_STATIC_FUNCTION (__LIBGCC_INIT_SECTION_ASM_OP__, __do_global_ctors_aux)
675 #else  /* OBJECT_FORMAT_ELF */
676 
677 /* Stick the real initialization code, followed by a normal sort of
678    function epilogue at the very end of the .init section for this
679    entire root executable file or for this entire shared library file.
680 
681    Note that we use some tricks here to get *just* the body and just
682    a function epilogue (but no function prologue) into the .init
683    section of the crtend.o file.  Specifically, we switch to the .text
684    section, start to define a function, and then we switch to the .init
685    section just before the body code.
686 
687    Earlier on, we put the corresponding function prologue into the .init
688    section of the crtbegin.o file (which will be linked in first).
689 
690    Note that we want to invoke all constructors for C++ file-scope static-
691    storage objects AFTER any other possible initialization actions which
692    may be performed by the code in the .init section contributions made by
693    other libraries, etc.  That's because those other initializations may
694    include setup operations for very primitive things (e.g. initializing
695    the state of the floating-point coprocessor, etc.) which should be done
696    before we start to execute any of the user's code.  */
697 
698 static void
699 __do_global_ctors_aux (void)	/* prologue goes in .text section */
700 {
701   asm (__LIBGCC_INIT_SECTION_ASM_OP__);
702   DO_GLOBAL_CTORS_BODY;
703   atexit (__do_global_dtors);
704 }				/* epilogue and body go in .init section */
705 
706 FORCE_CODE_SECTION_ALIGN
707 asm (__LIBGCC_TEXT_SECTION_ASM_OP__);
708 
709 #endif /* OBJECT_FORMAT_ELF */
710 
711 #elif defined(HAS_INIT_SECTION) /* ! __LIBGCC_INIT_SECTION_ASM_OP__ */
712 
713 extern void __do_global_ctors (void);
714 
715 /* This case is used by the Irix 6 port, which supports named sections but
716    not an SVR4-style .init section.  __do_global_ctors can be non-static
717    in this case because we protect it with -hidden_symbol.  */
718 void
719 __do_global_ctors (void)
720 {
721   func_ptr *p;
722 #if defined(USE_EH_FRAME_REGISTRY) \
723     || defined(USE_TM_CLONE_REGISTRY)
724   __do_global_ctors_1();
725 #endif
726   for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
727     (*p) ();
728 }
729 
730 #else /* ! __LIBGCC_INIT_SECTION_ASM_OP__ && ! HAS_INIT_SECTION */
731 #error "What are you doing with crtstuff.c, then?"
732 #endif
733 
734 #else /* ! CRT_BEGIN && ! CRT_END */
735 #error "One of CRT_BEGIN or CRT_END must be defined."
736 #endif
737