Missed one in last change.
[official-gcc.git] / gcc / crtstuff.c
bloba5c46d602a5e0128dc05951a11633b6f4b264160
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 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, 59 Temple Place - Suite 330, Boston, MA
31 02111-1307, 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 /* It is incorrect to include config.h here, because this file is being
55 compiled for the target, and hence definitions concerning only the host
56 do not apply. */
58 /* We include auto-host.h here to get HAVE_GAS_HIDDEN. This is
59 supposedly valid even though this is a "target" file. */
60 #include "auto-host.h"
61 #include "tconfig.h"
62 #include "tsystem.h"
63 #include "coretypes.h"
64 #include "tm.h"
65 #include "unwind-dw2-fde.h"
67 #ifndef FORCE_CODE_SECTION_ALIGN
68 # define FORCE_CODE_SECTION_ALIGN
69 #endif
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 (TEXT_SECTION_ASM_OP); \
81 #endif
83 #if defined(OBJECT_FORMAT_ELF) && defined(HAVE_LD_EH_FRAME_HDR) \
84 && !defined(inhibit_libc) && !defined(CRTSTUFFT_O) \
85 && defined(__GLIBC__) && __GLIBC__ >= 2
86 #include <link.h>
87 # if (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2) \
88 || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && defined(DT_CONFIG)))
89 # define USE_PT_GNU_EH_FRAME
90 # endif
91 #endif
92 #if defined(EH_FRAME_SECTION_NAME) && !defined(USE_PT_GNU_EH_FRAME)
93 # define USE_EH_FRAME_REGISTRY
94 #endif
95 #if defined(EH_FRAME_SECTION_NAME) && defined(HAVE_LD_RO_RW_SECTION_MIXING)
96 # define EH_FRAME_SECTION_CONST const
97 #else
98 # define EH_FRAME_SECTION_CONST
99 #endif
101 /* We do not want to add the weak attribute to the declarations of these
102 routines in unwind-dw2-fde.h because that will cause the definition of
103 these symbols to be weak as well.
105 This exposes a core issue, how to handle creating weak references vs
106 how to create weak definitions. Either we have to have the definition
107 of TARGET_WEAK_ATTRIBUTE be conditional in the shared header files or
108 have a second declaration if we want a function's references to be weak,
109 but not its definition.
111 Making TARGET_WEAK_ATTRIBUTE conditional seems like a good solution until
112 one thinks about scaling to larger problems -- ie, the condition under
113 which TARGET_WEAK_ATTRIBUTE is active will eventually get far too
114 complicated.
116 So, we take an approach similar to #pragma weak -- we have a second
117 declaration for functions that we want to have weak references.
119 Neither way is particularly good. */
121 /* References to __register_frame_info and __deregister_frame_info should
122 be weak in this file if at all possible. */
123 extern void __register_frame_info (void *, struct object *)
124 TARGET_ATTRIBUTE_WEAK;
125 extern void __register_frame_info_bases (void *, struct object *,
126 void *, void *)
127 TARGET_ATTRIBUTE_WEAK;
128 extern void *__deregister_frame_info (void *)
129 TARGET_ATTRIBUTE_WEAK;
130 extern void *__deregister_frame_info_bases (void *)
131 TARGET_ATTRIBUTE_WEAK;
133 /* Likewise for _Jv_RegisterClasses. */
134 extern void _Jv_RegisterClasses (void *) TARGET_ATTRIBUTE_WEAK;
136 #ifdef OBJECT_FORMAT_ELF
138 /* Declare a pointer to void function type. */
139 typedef void (*func_ptr) (void);
140 #define STATIC static
142 #else /* OBJECT_FORMAT_ELF */
144 #include "gbl-ctors.h"
146 #define STATIC
148 #endif /* OBJECT_FORMAT_ELF */
150 #ifdef CRT_BEGIN
152 /* NOTE: In order to be able to support SVR4 shared libraries, we arrange
153 to have one set of symbols { __CTOR_LIST__, __DTOR_LIST__, __CTOR_END__,
154 __DTOR_END__ } per root executable and also one set of these symbols
155 per shared library. So in any given whole process image, we may have
156 multiple definitions of each of these symbols. In order to prevent
157 these definitions from conflicting with one another, and in order to
158 ensure that the proper lists are used for the initialization/finalization
159 of each individual shared library (respectively), we give these symbols
160 only internal (i.e. `static') linkage, and we also make it a point to
161 refer to only the __CTOR_END__ symbol in crtend.o and the __DTOR_LIST__
162 symbol in crtbegin.o, where they are defined. */
164 /* The -1 is a flag to __do_global_[cd]tors indicating that this table
165 does not start with a count of elements. */
166 #ifdef CTOR_LIST_BEGIN
167 CTOR_LIST_BEGIN;
168 #elif defined(CTORS_SECTION_ASM_OP)
169 /* Hack: force cc1 to switch to .data section early, so that assembling
170 __CTOR_LIST__ does not undo our behind-the-back change to .ctors. */
171 static func_ptr force_to_data[1] __attribute__ ((__unused__)) = { };
172 asm (CTORS_SECTION_ASM_OP);
173 STATIC func_ptr __CTOR_LIST__[1]
174 __attribute__ ((__unused__, aligned(sizeof(func_ptr))))
175 = { (func_ptr) (-1) };
176 #else
177 STATIC func_ptr __CTOR_LIST__[1]
178 __attribute__ ((__unused__, section(".ctors"), aligned(sizeof(func_ptr))))
179 = { (func_ptr) (-1) };
180 #endif /* __CTOR_LIST__ alternatives */
182 #ifdef DTOR_LIST_BEGIN
183 DTOR_LIST_BEGIN;
184 #elif defined(DTORS_SECTION_ASM_OP)
185 asm (DTORS_SECTION_ASM_OP);
186 STATIC func_ptr __DTOR_LIST__[1]
187 __attribute__ ((aligned(sizeof(func_ptr))))
188 = { (func_ptr) (-1) };
189 #else
190 STATIC func_ptr __DTOR_LIST__[1]
191 __attribute__((section(".dtors"), aligned(sizeof(func_ptr))))
192 = { (func_ptr) (-1) };
193 #endif /* __DTOR_LIST__ alternatives */
195 #ifdef USE_EH_FRAME_REGISTRY
196 /* Stick a label at the beginning of the frame unwind info so we can register
197 and deregister it with the exception handling library code. */
198 STATIC EH_FRAME_SECTION_CONST char __EH_FRAME_BEGIN__[]
199 __attribute__((section(EH_FRAME_SECTION_NAME), aligned(4)))
200 = { };
201 #endif /* USE_EH_FRAME_REGISTRY */
203 #ifdef JCR_SECTION_NAME
204 /* Stick a label at the beginning of the java class registration info
205 so we can register them properly. */
206 STATIC void *__JCR_LIST__[]
207 __attribute__ ((unused, section(JCR_SECTION_NAME), aligned(sizeof(void*))))
208 = { };
209 #endif /* JCR_SECTION_NAME */
211 #ifdef INIT_SECTION_ASM_OP
213 #ifdef OBJECT_FORMAT_ELF
215 /* Declare the __dso_handle variable. It should have a unique value
216 in every shared-object; in a main program its value is zero. The
217 object should in any case be protected. This means the instance
218 in one DSO or the main program is not used in another object. The
219 dynamic linker takes care of this. */
221 #ifdef HAVE_GAS_HIDDEN
222 extern void *__dso_handle __attribute__ ((__visibility__ ("hidden")));
223 #endif
224 #ifdef CRTSTUFFS_O
225 void *__dso_handle = &__dso_handle;
226 #else
227 void *__dso_handle = 0;
228 #endif
230 /* The __cxa_finalize function may not be available so we use only a
231 weak declaration. */
232 extern void __cxa_finalize (void *) TARGET_ATTRIBUTE_WEAK;
234 /* Run all the global destructors on exit from the program. */
236 /* Some systems place the number of pointers in the first word of the
237 table. On SVR4 however, that word is -1. In all cases, the table is
238 null-terminated. On SVR4, we start from the beginning of the list and
239 invoke each per-compilation-unit destructor routine in order
240 until we find that null.
242 Note that this function MUST be static. There will be one of these
243 functions in each root executable and one in each shared library, but
244 although they all have the same code, each one is unique in that it
245 refers to one particular associated `__DTOR_LIST__' which belongs to the
246 same particular root executable or shared library file.
248 On some systems, this routine is run more than once from the .fini,
249 when exit is called recursively, so we arrange to remember where in
250 the list we left off processing, and we resume at that point,
251 should we be re-invoked. */
253 static void __attribute__((used))
254 __do_global_dtors_aux (void)
256 static func_ptr *p = __DTOR_LIST__ + 1;
257 static _Bool completed;
258 func_ptr f;
260 if (__builtin_expect (completed, 0))
261 return;
263 #ifdef CRTSTUFFS_O
264 if (__cxa_finalize)
265 __cxa_finalize (__dso_handle);
266 #endif
268 while ((f = *p))
270 p++;
271 f ();
274 #ifdef USE_EH_FRAME_REGISTRY
275 #ifdef CRT_GET_RFIB_DATA
276 /* If we used the new __register_frame_info_bases interface,
277 make sure that we deregister from the same place. */
278 if (__deregister_frame_info_bases)
279 __deregister_frame_info_bases (__EH_FRAME_BEGIN__);
280 #else
281 if (__deregister_frame_info)
282 __deregister_frame_info (__EH_FRAME_BEGIN__);
283 #endif
284 #endif
286 completed = 1;
289 /* Stick a call to __do_global_dtors_aux into the .fini section. */
290 CRT_CALL_STATIC_FUNCTION (FINI_SECTION_ASM_OP, __do_global_dtors_aux)
292 #if defined(USE_EH_FRAME_REGISTRY) || defined(JCR_SECTION_NAME)
293 /* Stick a call to __register_frame_info into the .init section. For some
294 reason calls with no arguments work more reliably in .init, so stick the
295 call in another function. */
297 static void __attribute__((used))
298 frame_dummy (void)
300 #ifdef USE_EH_FRAME_REGISTRY
301 static struct object object;
302 #ifdef CRT_GET_RFIB_DATA
303 void *tbase, *dbase;
304 tbase = 0;
305 CRT_GET_RFIB_DATA (dbase);
306 if (__register_frame_info_bases)
307 __register_frame_info_bases (__EH_FRAME_BEGIN__, &object, tbase, dbase);
308 #else
309 if (__register_frame_info)
310 __register_frame_info (__EH_FRAME_BEGIN__, &object);
311 #endif /* CRT_GET_RFIB_DATA */
312 #endif /* USE_EH_FRAME_REGISTRY */
313 #ifdef JCR_SECTION_NAME
314 if (__JCR_LIST__[0] && _Jv_RegisterClasses)
315 _Jv_RegisterClasses (__JCR_LIST__);
316 #endif /* JCR_SECTION_NAME */
319 CRT_CALL_STATIC_FUNCTION (INIT_SECTION_ASM_OP, frame_dummy)
320 #endif /* USE_EH_FRAME_REGISTRY || JCR_SECTION_NAME */
322 #else /* OBJECT_FORMAT_ELF */
324 /* The function __do_global_ctors_aux is compiled twice (once in crtbegin.o
325 and once in crtend.o). It must be declared static to avoid a link
326 error. Here, we define __do_global_ctors as an externally callable
327 function. It is externally callable so that __main can invoke it when
328 INVOKE__main is defined. This has the additional effect of forcing cc1
329 to switch to the .text section. */
331 static void __do_global_ctors_aux (void);
332 void
333 __do_global_ctors (void)
335 #ifdef INVOKE__main
336 /* If __main won't actually call __do_global_ctors then it doesn't matter
337 what's inside the function. The inside of __do_global_ctors_aux is
338 called automatically in that case. And the Alliant fx2800 linker
339 crashes on this reference. So prevent the crash. */
340 __do_global_ctors_aux ();
341 #endif
344 asm (INIT_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
346 /* A routine to invoke all of the global constructors upon entry to the
347 program. We put this into the .init section (for systems that have
348 such a thing) so that we can properly perform the construction of
349 file-scope static-storage C++ objects within shared libraries. */
351 static void __attribute__((used))
352 __do_global_ctors_aux (void) /* prologue goes in .init section */
354 FORCE_CODE_SECTION_ALIGN /* explicit align before switch to .text */
355 asm (TEXT_SECTION_ASM_OP); /* don't put epilogue and body in .init */
356 DO_GLOBAL_CTORS_BODY;
357 atexit (__do_global_dtors);
360 #endif /* OBJECT_FORMAT_ELF */
362 #elif defined(HAS_INIT_SECTION) /* ! INIT_SECTION_ASM_OP */
364 /* This case is used by the Irix 6 port, which supports named sections but
365 not an SVR4-style .fini section. __do_global_dtors can be non-static
366 in this case because we protect it with -hidden_symbol. */
368 void
369 __do_global_dtors (void)
371 func_ptr *p, f;
372 for (p = __DTOR_LIST__ + 1; (f = *p); p++)
373 f ();
375 #ifdef USE_EH_FRAME_REGISTRY
376 if (__deregister_frame_info)
377 __deregister_frame_info (__EH_FRAME_BEGIN__);
378 #endif
381 #if defined(USE_EH_FRAME_REGISTRY) || defined(JCR_SECTION_NAME)
382 /* A helper function for __do_global_ctors, which is in crtend.o. Here
383 in crtbegin.o, we can reference a couple of symbols not visible there.
384 Plus, since we're before libgcc.a, we have no problems referencing
385 functions from there. */
386 void
387 __do_global_ctors_1(void)
389 #ifdef USE_EH_FRAME_REGISTRY
390 static struct object object;
391 if (__register_frame_info)
392 __register_frame_info (__EH_FRAME_BEGIN__, &object);
393 #endif
394 #ifdef JCR_SECTION_NAME
395 if (__JCR_LIST__[0] && _Jv_RegisterClasses)
396 _Jv_RegisterClasses (__JCR_LIST__);
397 #endif
399 #endif /* USE_EH_FRAME_REGISTRY || JCR_SECTION_NAME */
401 #else /* ! INIT_SECTION_ASM_OP && ! HAS_INIT_SECTION */
402 #error "What are you doing with crtstuff.c, then?"
403 #endif
405 #elif defined(CRT_END) /* ! CRT_BEGIN */
407 /* Put a word containing zero at the end of each of our two lists of function
408 addresses. Note that the words defined here go into the .ctors and .dtors
409 sections of the crtend.o file, and since that file is always linked in
410 last, these words naturally end up at the very ends of the two lists
411 contained in these two sections. */
413 #ifdef CTOR_LIST_END
414 CTOR_LIST_END;
415 #elif defined(CTORS_SECTION_ASM_OP)
416 /* Hack: force cc1 to switch to .data section early, so that assembling
417 __CTOR_LIST__ does not undo our behind-the-back change to .ctors. */
418 static func_ptr force_to_data[1] __attribute__ ((__unused__)) = { };
419 asm (CTORS_SECTION_ASM_OP);
420 STATIC func_ptr __CTOR_END__[1]
421 __attribute__((aligned(sizeof(func_ptr))))
422 = { (func_ptr) 0 };
423 #else
424 STATIC func_ptr __CTOR_END__[1]
425 __attribute__((section(".ctors"), aligned(sizeof(func_ptr))))
426 = { (func_ptr) 0 };
427 #endif
429 #ifdef DTOR_LIST_END
430 DTOR_LIST_END;
431 #elif defined(DTORS_SECTION_ASM_OP)
432 asm (DTORS_SECTION_ASM_OP);
433 STATIC func_ptr __DTOR_END__[1]
434 __attribute__ ((unused, aligned(sizeof(func_ptr))))
435 = { (func_ptr) 0 };
436 #else
437 STATIC func_ptr __DTOR_END__[1]
438 __attribute__((unused, section(".dtors"), aligned(sizeof(func_ptr))))
439 = { (func_ptr) 0 };
440 #endif
442 #ifdef EH_FRAME_SECTION_NAME
443 /* Terminate the frame unwind info section with a 4byte 0 as a sentinel;
444 this would be the 'length' field in a real FDE. */
445 STATIC EH_FRAME_SECTION_CONST int __FRAME_END__[]
446 __attribute__ ((unused, mode(SI), section(EH_FRAME_SECTION_NAME),
447 aligned(4)))
448 = { 0 };
449 #endif /* EH_FRAME_SECTION_NAME */
451 #ifdef JCR_SECTION_NAME
452 /* Null terminate the .jcr section array. */
453 STATIC void *__JCR_END__[1]
454 __attribute__ ((unused, section(JCR_SECTION_NAME),
455 aligned(sizeof(void *))))
456 = { 0 };
457 #endif /* JCR_SECTION_NAME */
459 #ifdef INIT_SECTION_ASM_OP
461 #ifdef OBJECT_FORMAT_ELF
462 static void __attribute__((used))
463 __do_global_ctors_aux (void)
465 func_ptr *p;
466 for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
467 (*p) ();
470 /* Stick a call to __do_global_ctors_aux into the .init section. */
471 CRT_CALL_STATIC_FUNCTION (INIT_SECTION_ASM_OP, __do_global_ctors_aux)
472 #else /* OBJECT_FORMAT_ELF */
474 /* Stick the real initialization code, followed by a normal sort of
475 function epilogue at the very end of the .init section for this
476 entire root executable file or for this entire shared library file.
478 Note that we use some tricks here to get *just* the body and just
479 a function epilogue (but no function prologue) into the .init
480 section of the crtend.o file. Specifically, we switch to the .text
481 section, start to define a function, and then we switch to the .init
482 section just before the body code.
484 Earlier on, we put the corresponding function prologue into the .init
485 section of the crtbegin.o file (which will be linked in first).
487 Note that we want to invoke all constructors for C++ file-scope static-
488 storage objects AFTER any other possible initialization actions which
489 may be performed by the code in the .init section contributions made by
490 other libraries, etc. That's because those other initializations may
491 include setup operations for very primitive things (e.g. initializing
492 the state of the floating-point coprocessor, etc.) which should be done
493 before we start to execute any of the user's code. */
495 static void
496 __do_global_ctors_aux (void) /* prologue goes in .text section */
498 asm (INIT_SECTION_ASM_OP);
499 DO_GLOBAL_CTORS_BODY;
500 atexit (__do_global_dtors);
501 } /* epilogue and body go in .init section */
503 FORCE_CODE_SECTION_ALIGN
504 asm (TEXT_SECTION_ASM_OP);
506 #endif /* OBJECT_FORMAT_ELF */
508 #elif defined(HAS_INIT_SECTION) /* ! INIT_SECTION_ASM_OP */
510 /* This case is used by the Irix 6 port, which supports named sections but
511 not an SVR4-style .init section. __do_global_ctors can be non-static
512 in this case because we protect it with -hidden_symbol. */
513 extern void __do_global_ctors_1(void);
514 void
515 __do_global_ctors (void)
517 func_ptr *p;
518 #if defined(USE_EH_FRAME_REGISTRY) || defined(JCR_SECTION_NAME)
519 __do_global_ctors_1();
520 #endif
521 for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
522 (*p) ();
525 #else /* ! INIT_SECTION_ASM_OP && ! HAS_INIT_SECTION */
526 #error "What are you doing with crtstuff.c, then?"
527 #endif
529 #else /* ! CRT_BEGIN && ! CRT_END */
530 #error "One of CRT_BEGIN or CRT_END must be defined."
531 #endif