2006-03-15 Paul Brook <paul@codesourcery.com>
[official-gcc.git] / gcc / crtstuff.c
blobcde7557313237893f8f9f79aaf4246af58c78e30
1 /* Specialized bits of code needed to support construction and
2 destruction of file-scope objects in C++ code.
3 Copyright (C) 1991, 1994, 1995, 1996, 1997, 1998,
4 1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
5 Contributed by Ron Guilmette (rfg@monkeys.com).
7 This file is part of GCC.
9 GCC is free software; you can redistribute it and/or modify it under
10 the terms of the GNU General Public License as published by the Free
11 Software Foundation; either version 2, or (at your option) any later
12 version.
14 In addition to the permissions in the GNU General Public License, the
15 Free Software Foundation gives you unlimited permission to link the
16 compiled version of this file into combinations with other programs,
17 and to distribute those combinations without any restriction coming
18 from the use of this file. (The General Public License restrictions
19 do apply in other respects; for example, they cover modification of
20 the file, and distribution when not linked into a combine
21 executable.)
23 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
24 WARRANTY; without even the implied warranty of MERCHANTABILITY or
25 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
26 for more details.
28 You should have received a copy of the GNU General Public License
29 along with GCC; see the file COPYING. If not, write to the Free
30 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
31 02110-1301, USA. */
33 /* This file is a bit like libgcc2.c in that it is compiled
34 multiple times and yields multiple .o files.
36 This file is useful on target machines where the object file format
37 supports multiple "user-defined" sections (e.g. COFF, ELF, ROSE). On
38 such systems, this file allows us to avoid running collect (or any
39 other such slow and painful kludge). Additionally, if the target
40 system supports a .init section, this file allows us to support the
41 linking of C++ code with a non-C++ main program.
43 Note that if INIT_SECTION_ASM_OP is defined in the tm.h file, then
44 this file *will* make use of the .init section. If that symbol is
45 not defined however, then the .init section will not be used.
47 Currently, only ELF and COFF are supported. It is likely however that
48 ROSE could also be supported, if someone was willing to do the work to
49 make whatever (small?) adaptations are needed. (Some work may be
50 needed on the ROSE assembler and linker also.)
52 This file must be compiled with gcc. */
54 /* Target machine header files require this define. */
55 #define IN_LIBGCC2
57 /* FIXME: Including auto-host is incorrect, but until we have
58 identified the set of defines that need to go into auto-target.h,
59 this will have to do. */
60 #include "auto-host.h"
61 #undef gid_t
62 #undef pid_t
63 #undef rlim_t
64 #undef ssize_t
65 #undef uid_t
66 #undef vfork
67 #include "tconfig.h"
68 #include "tsystem.h"
69 #include "coretypes.h"
70 #include "tm.h"
71 #include "unwind-dw2-fde.h"
73 #ifndef FORCE_CODE_SECTION_ALIGN
74 # define FORCE_CODE_SECTION_ALIGN
75 #endif
77 #ifndef CRT_CALL_STATIC_FUNCTION
78 # define CRT_CALL_STATIC_FUNCTION(SECTION_OP, FUNC) \
79 static void __attribute__((__used__)) \
80 call_ ## FUNC (void) \
81 { \
82 asm (SECTION_OP); \
83 FUNC (); \
84 FORCE_CODE_SECTION_ALIGN \
85 asm (TEXT_SECTION_ASM_OP); \
87 #endif
89 #if defined(OBJECT_FORMAT_ELF) && defined(HAVE_LD_EH_FRAME_HDR) \
90 && !defined(inhibit_libc) && !defined(CRTSTUFFT_O) \
91 && defined(__GLIBC__) && __GLIBC__ >= 2
92 #include <link.h>
93 # if (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2) \
94 || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && defined(DT_CONFIG)))
95 # define USE_PT_GNU_EH_FRAME
96 # endif
97 #endif
98 #if defined(EH_FRAME_SECTION_NAME) && !defined(USE_PT_GNU_EH_FRAME)
99 # define USE_EH_FRAME_REGISTRY
100 #endif
101 #if defined(EH_FRAME_SECTION_NAME) && EH_TABLES_CAN_BE_READ_ONLY
102 # define EH_FRAME_SECTION_CONST const
103 #else
104 # define EH_FRAME_SECTION_CONST
105 #endif
107 /* We do not want to add the weak attribute to the declarations of these
108 routines in unwind-dw2-fde.h because that will cause the definition of
109 these symbols to be weak as well.
111 This exposes a core issue, how to handle creating weak references vs
112 how to create weak definitions. Either we have to have the definition
113 of TARGET_WEAK_ATTRIBUTE be conditional in the shared header files or
114 have a second declaration if we want a function's references to be weak,
115 but not its definition.
117 Making TARGET_WEAK_ATTRIBUTE conditional seems like a good solution until
118 one thinks about scaling to larger problems -- i.e., the condition under
119 which TARGET_WEAK_ATTRIBUTE is active will eventually get far too
120 complicated.
122 So, we take an approach similar to #pragma weak -- we have a second
123 declaration for functions that we want to have weak references.
125 Neither way is particularly good. */
127 /* References to __register_frame_info and __deregister_frame_info should
128 be weak in this file if at all possible. */
129 extern void __register_frame_info (const void *, struct object *)
130 TARGET_ATTRIBUTE_WEAK;
131 extern void __register_frame_info_bases (const void *, struct object *,
132 void *, void *)
133 TARGET_ATTRIBUTE_WEAK;
134 extern void *__deregister_frame_info (const void *)
135 TARGET_ATTRIBUTE_WEAK;
136 extern void *__deregister_frame_info_bases (const void *)
137 TARGET_ATTRIBUTE_WEAK;
138 extern void __do_global_ctors_1 (void);
140 /* Likewise for _Jv_RegisterClasses. */
141 extern void _Jv_RegisterClasses (void *) TARGET_ATTRIBUTE_WEAK;
143 #ifdef OBJECT_FORMAT_ELF
145 /* Declare a pointer to void function type. */
146 typedef void (*func_ptr) (void);
147 #define STATIC static
149 #else /* OBJECT_FORMAT_ELF */
151 #include "gbl-ctors.h"
153 #define STATIC
155 #endif /* OBJECT_FORMAT_ELF */
157 #ifdef CRT_BEGIN
159 /* NOTE: In order to be able to support SVR4 shared libraries, we arrange
160 to have one set of symbols { __CTOR_LIST__, __DTOR_LIST__, __CTOR_END__,
161 __DTOR_END__ } per root executable and also one set of these symbols
162 per shared library. So in any given whole process image, we may have
163 multiple definitions of each of these symbols. In order to prevent
164 these definitions from conflicting with one another, and in order to
165 ensure that the proper lists are used for the initialization/finalization
166 of each individual shared library (respectively), we give these symbols
167 only internal (i.e. `static') linkage, and we also make it a point to
168 refer to only the __CTOR_END__ symbol in crtend.o and the __DTOR_LIST__
169 symbol in crtbegin.o, where they are defined. */
171 /* The -1 is a flag to __do_global_[cd]tors indicating that this table
172 does not start with a count of elements. */
173 #ifdef CTOR_LIST_BEGIN
174 CTOR_LIST_BEGIN;
175 #elif defined(CTORS_SECTION_ASM_OP)
176 /* Hack: force cc1 to switch to .data section early, so that assembling
177 __CTOR_LIST__ does not undo our behind-the-back change to .ctors. */
178 static func_ptr force_to_data[1] __attribute__ ((__unused__)) = { };
179 asm (CTORS_SECTION_ASM_OP);
180 STATIC func_ptr __CTOR_LIST__[1]
181 __attribute__ ((__unused__, aligned(sizeof(func_ptr))))
182 = { (func_ptr) (-1) };
183 #else
184 STATIC func_ptr __CTOR_LIST__[1]
185 __attribute__ ((__unused__, section(".ctors"), aligned(sizeof(func_ptr))))
186 = { (func_ptr) (-1) };
187 #endif /* __CTOR_LIST__ alternatives */
189 #ifdef DTOR_LIST_BEGIN
190 DTOR_LIST_BEGIN;
191 #elif defined(DTORS_SECTION_ASM_OP)
192 asm (DTORS_SECTION_ASM_OP);
193 STATIC func_ptr __DTOR_LIST__[1]
194 __attribute__ ((aligned(sizeof(func_ptr))))
195 = { (func_ptr) (-1) };
196 #else
197 STATIC func_ptr __DTOR_LIST__[1]
198 __attribute__((section(".dtors"), aligned(sizeof(func_ptr))))
199 = { (func_ptr) (-1) };
200 #endif /* __DTOR_LIST__ alternatives */
202 #ifdef USE_EH_FRAME_REGISTRY
203 /* Stick a label at the beginning of the frame unwind info so we can register
204 and deregister it with the exception handling library code. */
205 STATIC EH_FRAME_SECTION_CONST char __EH_FRAME_BEGIN__[]
206 __attribute__((section(EH_FRAME_SECTION_NAME), aligned(4)))
207 = { };
208 #endif /* USE_EH_FRAME_REGISTRY */
210 #ifdef JCR_SECTION_NAME
211 /* Stick a label at the beginning of the java class registration info
212 so we can register them properly. */
213 STATIC void *__JCR_LIST__[]
214 __attribute__ ((unused, section(JCR_SECTION_NAME), aligned(sizeof(void*))))
215 = { };
216 #endif /* JCR_SECTION_NAME */
218 #if defined(INIT_SECTION_ASM_OP) || defined(INIT_ARRAY_SECTION_ASM_OP)
220 #ifdef OBJECT_FORMAT_ELF
222 /* Declare the __dso_handle variable. It should have a unique value
223 in every shared-object; in a main program its value is zero. The
224 object should in any case be protected. This means the instance
225 in one DSO or the main program is not used in another object. The
226 dynamic linker takes care of this. */
228 #ifdef HAVE_GAS_HIDDEN
229 extern void *__dso_handle __attribute__ ((__visibility__ ("hidden")));
230 #endif
231 #ifdef CRTSTUFFS_O
232 void *__dso_handle = &__dso_handle;
233 #else
234 void *__dso_handle = 0;
235 #endif
237 /* The __cxa_finalize function may not be available so we use only a
238 weak declaration. */
239 extern void __cxa_finalize (void *) TARGET_ATTRIBUTE_WEAK;
241 /* Run all the global destructors on exit from the program. */
243 /* Some systems place the number of pointers in the first word of the
244 table. On SVR4 however, that word is -1. In all cases, the table is
245 null-terminated. On SVR4, we start from the beginning of the list and
246 invoke each per-compilation-unit destructor routine in order
247 until we find that null.
249 Note that this function MUST be static. There will be one of these
250 functions in each root executable and one in each shared library, but
251 although they all have the same code, each one is unique in that it
252 refers to one particular associated `__DTOR_LIST__' which belongs to the
253 same particular root executable or shared library file.
255 On some systems, this routine is run more than once from the .fini,
256 when exit is called recursively, so we arrange to remember where in
257 the list we left off processing, and we resume at that point,
258 should we be re-invoked. */
260 static void __attribute__((used))
261 __do_global_dtors_aux (void)
263 #ifndef FINI_ARRAY_SECTION_ASM_OP
264 static func_ptr *p = __DTOR_LIST__ + 1;
265 func_ptr f;
266 #endif /* !defined(FINI_ARRAY_SECTION_ASM_OP) */
267 static _Bool completed;
269 if (__builtin_expect (completed, 0))
270 return;
272 #ifdef CRTSTUFFS_O
273 if (__cxa_finalize)
274 __cxa_finalize (__dso_handle);
275 #endif
277 #ifdef FINI_ARRAY_SECTION_ASM_OP
278 /* If we are using .fini_array then destructors will be run via that
279 mechanism. */
280 #else /* !defined (FINI_ARRAY_SECTION_ASM_OP) */
281 while ((f = *p))
283 p++;
284 f ();
286 #endif /* !defined(FINI_ARRAY_SECTION_ASM_OP) */
288 #ifdef USE_EH_FRAME_REGISTRY
289 #ifdef CRT_GET_RFIB_DATA
290 /* If we used the new __register_frame_info_bases interface,
291 make sure that we deregister from the same place. */
292 if (__deregister_frame_info_bases)
293 __deregister_frame_info_bases (__EH_FRAME_BEGIN__);
294 #else
295 if (__deregister_frame_info)
296 __deregister_frame_info (__EH_FRAME_BEGIN__);
297 #endif
298 #endif
300 completed = 1;
303 /* Stick a call to __do_global_dtors_aux into the .fini section. */
304 #ifdef FINI_SECTION_ASM_OP
305 CRT_CALL_STATIC_FUNCTION (FINI_SECTION_ASM_OP, __do_global_dtors_aux)
306 #else /* !defined(FINI_SECTION_ASM_OP) */
307 static func_ptr __do_global_dtors_aux_fini_array_entry[]
308 __attribute__ ((__unused__, section(".fini_array")))
309 = { __do_global_dtors_aux };
310 #endif /* !defined(FINI_SECTION_ASM_OP) */
312 #if defined(USE_EH_FRAME_REGISTRY) || defined(JCR_SECTION_NAME)
313 /* Stick a call to __register_frame_info into the .init section. For some
314 reason calls with no arguments work more reliably in .init, so stick the
315 call in another function. */
317 static void __attribute__((used))
318 frame_dummy (void)
320 #ifdef USE_EH_FRAME_REGISTRY
321 static struct object object;
322 #ifdef CRT_GET_RFIB_DATA
323 void *tbase, *dbase;
324 tbase = 0;
325 CRT_GET_RFIB_DATA (dbase);
326 if (__register_frame_info_bases)
327 __register_frame_info_bases (__EH_FRAME_BEGIN__, &object, tbase, dbase);
328 #else
329 if (__register_frame_info)
330 __register_frame_info (__EH_FRAME_BEGIN__, &object);
331 #endif /* CRT_GET_RFIB_DATA */
332 #endif /* USE_EH_FRAME_REGISTRY */
333 #ifdef JCR_SECTION_NAME
334 if (__JCR_LIST__[0])
336 void (*register_classes) (void *) = _Jv_RegisterClasses;
337 __asm ("" : "+r" (register_classes));
338 if (register_classes)
339 register_classes (__JCR_LIST__);
341 #endif /* JCR_SECTION_NAME */
344 #ifdef INIT_SECTION_ASM_OP
345 CRT_CALL_STATIC_FUNCTION (INIT_SECTION_ASM_OP, frame_dummy)
346 #else /* defined(INIT_SECTION_ASM_OP) */
347 static func_ptr __frame_dummy_init_array_entry[]
348 __attribute__ ((__unused__, section(".init_array")))
349 = { frame_dummy };
350 #endif /* !defined(INIT_SECTION_ASM_OP) */
351 #endif /* USE_EH_FRAME_REGISTRY || JCR_SECTION_NAME */
353 #else /* OBJECT_FORMAT_ELF */
355 /* The function __do_global_ctors_aux is compiled twice (once in crtbegin.o
356 and once in crtend.o). It must be declared static to avoid a link
357 error. Here, we define __do_global_ctors as an externally callable
358 function. It is externally callable so that __main can invoke it when
359 INVOKE__main is defined. This has the additional effect of forcing cc1
360 to switch to the .text section. */
362 static void __do_global_ctors_aux (void);
363 void
364 __do_global_ctors (void)
366 #ifdef INVOKE__main
367 /* If __main won't actually call __do_global_ctors then it doesn't matter
368 what's inside the function. The inside of __do_global_ctors_aux is
369 called automatically in that case. And the Alliant fx2800 linker
370 crashes on this reference. So prevent the crash. */
371 __do_global_ctors_aux ();
372 #endif
375 asm (INIT_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
377 /* A routine to invoke all of the global constructors upon entry to the
378 program. We put this into the .init section (for systems that have
379 such a thing) so that we can properly perform the construction of
380 file-scope static-storage C++ objects within shared libraries. */
382 static void __attribute__((used))
383 __do_global_ctors_aux (void) /* prologue goes in .init section */
385 FORCE_CODE_SECTION_ALIGN /* explicit align before switch to .text */
386 asm (TEXT_SECTION_ASM_OP); /* don't put epilogue and body in .init */
387 DO_GLOBAL_CTORS_BODY;
388 atexit (__do_global_dtors);
391 #endif /* OBJECT_FORMAT_ELF */
393 #elif defined(HAS_INIT_SECTION) /* ! INIT_SECTION_ASM_OP */
395 extern void __do_global_dtors (void);
397 /* This case is used by the Irix 6 port, which supports named sections but
398 not an SVR4-style .fini section. __do_global_dtors can be non-static
399 in this case because we protect it with -hidden_symbol. */
401 void
402 __do_global_dtors (void)
404 func_ptr *p, f;
405 for (p = __DTOR_LIST__ + 1; (f = *p); p++)
406 f ();
408 #ifdef USE_EH_FRAME_REGISTRY
409 if (__deregister_frame_info)
410 __deregister_frame_info (__EH_FRAME_BEGIN__);
411 #endif
414 #if defined(USE_EH_FRAME_REGISTRY) || defined(JCR_SECTION_NAME)
415 /* A helper function for __do_global_ctors, which is in crtend.o. Here
416 in crtbegin.o, we can reference a couple of symbols not visible there.
417 Plus, since we're before libgcc.a, we have no problems referencing
418 functions from there. */
419 void
420 __do_global_ctors_1(void)
422 #ifdef USE_EH_FRAME_REGISTRY
423 static struct object object;
424 if (__register_frame_info)
425 __register_frame_info (__EH_FRAME_BEGIN__, &object);
426 #endif
427 #ifdef JCR_SECTION_NAME
428 if (__JCR_LIST__[0])
430 void (*register_classes) (void *) = _Jv_RegisterClasses;
431 __asm ("" : "+r" (register_classes));
432 if (register_classes)
433 register_classes (__JCR_LIST__);
435 #endif
437 #endif /* USE_EH_FRAME_REGISTRY || JCR_SECTION_NAME */
439 #else /* ! INIT_SECTION_ASM_OP && ! HAS_INIT_SECTION */
440 #error "What are you doing with crtstuff.c, then?"
441 #endif
443 #elif defined(CRT_END) /* ! CRT_BEGIN */
445 /* Put a word containing zero at the end of each of our two lists of function
446 addresses. Note that the words defined here go into the .ctors and .dtors
447 sections of the crtend.o file, and since that file is always linked in
448 last, these words naturally end up at the very ends of the two lists
449 contained in these two sections. */
451 #ifdef CTOR_LIST_END
452 CTOR_LIST_END;
453 #elif defined(CTORS_SECTION_ASM_OP)
454 /* Hack: force cc1 to switch to .data section early, so that assembling
455 __CTOR_LIST__ does not undo our behind-the-back change to .ctors. */
456 static func_ptr force_to_data[1] __attribute__ ((__unused__)) = { };
457 asm (CTORS_SECTION_ASM_OP);
458 STATIC func_ptr __CTOR_END__[1]
459 __attribute__((aligned(sizeof(func_ptr))))
460 = { (func_ptr) 0 };
461 #else
462 STATIC func_ptr __CTOR_END__[1]
463 __attribute__((section(".ctors"), aligned(sizeof(func_ptr))))
464 = { (func_ptr) 0 };
465 #endif
467 #ifdef DTOR_LIST_END
468 DTOR_LIST_END;
469 #elif defined(DTORS_SECTION_ASM_OP)
470 asm (DTORS_SECTION_ASM_OP);
471 STATIC func_ptr __DTOR_END__[1]
472 __attribute__ ((unused, aligned(sizeof(func_ptr))))
473 = { (func_ptr) 0 };
474 #else
475 STATIC func_ptr __DTOR_END__[1]
476 __attribute__((unused, section(".dtors"), aligned(sizeof(func_ptr))))
477 = { (func_ptr) 0 };
478 #endif
480 #ifdef EH_FRAME_SECTION_NAME
481 /* Terminate the frame unwind info section with a 4byte 0 as a sentinel;
482 this would be the 'length' field in a real FDE. */
483 # if __INT_MAX__ == 2147483647
484 typedef int int32;
485 # elif __LONG_MAX__ == 2147483647
486 typedef long int32;
487 # elif __SHRT_MAX__ == 2147483647
488 typedef short int32;
489 # else
490 # error "Missing a 4 byte integer"
491 # endif
492 STATIC EH_FRAME_SECTION_CONST int32 __FRAME_END__[]
493 __attribute__ ((unused, section(EH_FRAME_SECTION_NAME),
494 aligned(sizeof(int32))))
495 = { 0 };
496 #endif /* EH_FRAME_SECTION_NAME */
498 #ifdef JCR_SECTION_NAME
499 /* Null terminate the .jcr section array. */
500 STATIC void *__JCR_END__[1]
501 __attribute__ ((unused, section(JCR_SECTION_NAME),
502 aligned(sizeof(void *))))
503 = { 0 };
504 #endif /* JCR_SECTION_NAME */
506 #ifdef INIT_ARRAY_SECTION_ASM_OP
508 /* If we are using .init_array, there is nothing to do. */
510 #elif defined(INIT_SECTION_ASM_OP)
512 #ifdef OBJECT_FORMAT_ELF
513 static void __attribute__((used))
514 __do_global_ctors_aux (void)
516 func_ptr *p;
517 for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
518 (*p) ();
521 /* Stick a call to __do_global_ctors_aux into the .init section. */
522 CRT_CALL_STATIC_FUNCTION (INIT_SECTION_ASM_OP, __do_global_ctors_aux)
523 #else /* OBJECT_FORMAT_ELF */
525 /* Stick the real initialization code, followed by a normal sort of
526 function epilogue at the very end of the .init section for this
527 entire root executable file or for this entire shared library file.
529 Note that we use some tricks here to get *just* the body and just
530 a function epilogue (but no function prologue) into the .init
531 section of the crtend.o file. Specifically, we switch to the .text
532 section, start to define a function, and then we switch to the .init
533 section just before the body code.
535 Earlier on, we put the corresponding function prologue into the .init
536 section of the crtbegin.o file (which will be linked in first).
538 Note that we want to invoke all constructors for C++ file-scope static-
539 storage objects AFTER any other possible initialization actions which
540 may be performed by the code in the .init section contributions made by
541 other libraries, etc. That's because those other initializations may
542 include setup operations for very primitive things (e.g. initializing
543 the state of the floating-point coprocessor, etc.) which should be done
544 before we start to execute any of the user's code. */
546 static void
547 __do_global_ctors_aux (void) /* prologue goes in .text section */
549 asm (INIT_SECTION_ASM_OP);
550 DO_GLOBAL_CTORS_BODY;
551 atexit (__do_global_dtors);
552 } /* epilogue and body go in .init section */
554 FORCE_CODE_SECTION_ALIGN
555 asm (TEXT_SECTION_ASM_OP);
557 #endif /* OBJECT_FORMAT_ELF */
559 #elif defined(HAS_INIT_SECTION) /* ! INIT_SECTION_ASM_OP */
561 extern void __do_global_ctors (void);
563 /* This case is used by the Irix 6 port, which supports named sections but
564 not an SVR4-style .init section. __do_global_ctors can be non-static
565 in this case because we protect it with -hidden_symbol. */
566 void
567 __do_global_ctors (void)
569 func_ptr *p;
570 #if defined(USE_EH_FRAME_REGISTRY) || defined(JCR_SECTION_NAME)
571 __do_global_ctors_1();
572 #endif
573 for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
574 (*p) ();
577 #else /* ! INIT_SECTION_ASM_OP && ! HAS_INIT_SECTION */
578 #error "What are you doing with crtstuff.c, then?"
579 #endif
581 #else /* ! CRT_BEGIN && ! CRT_END */
582 #error "One of CRT_BEGIN or CRT_END must be defined."
583 #endif