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
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
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
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
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. */
59 #include "coretypes.h"
61 #include "unwind-dw2-fde.h"
63 #ifndef FORCE_CODE_SECTION_ALIGN
64 # define FORCE_CODE_SECTION_ALIGN
67 #ifndef CRT_CALL_STATIC_FUNCTION
68 # define CRT_CALL_STATIC_FUNCTION(SECTION_OP, FUNC) \
69 static void __attribute__((__used__)) \
70 call_ ## FUNC (void) \
74 FORCE_CODE_SECTION_ALIGN \
75 asm (TEXT_SECTION_ASM_OP); \
79 #if defined(OBJECT_FORMAT_ELF) && defined(HAVE_LD_EH_FRAME_HDR) \
80 && !defined(inhibit_libc) && !defined(CRTSTUFFT_O) \
81 && defined(__GLIBC__) && __GLIBC__ >= 2
83 # if (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2) \
84 || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && defined(DT_CONFIG)))
85 # define USE_PT_GNU_EH_FRAME
88 #if defined(EH_FRAME_SECTION_NAME) && !defined(USE_PT_GNU_EH_FRAME)
89 # define USE_EH_FRAME_REGISTRY
91 #if defined(EH_FRAME_SECTION_NAME) && EH_TABLES_CAN_BE_READ_ONLY
92 # define EH_FRAME_SECTION_CONST const
94 # define EH_FRAME_SECTION_CONST
97 /* We do not want to add the weak attribute to the declarations of these
98 routines in unwind-dw2-fde.h because that will cause the definition of
99 these symbols to be weak as well.
101 This exposes a core issue, how to handle creating weak references vs
102 how to create weak definitions. Either we have to have the definition
103 of TARGET_WEAK_ATTRIBUTE be conditional in the shared header files or
104 have a second declaration if we want a function's references to be weak,
105 but not its definition.
107 Making TARGET_WEAK_ATTRIBUTE conditional seems like a good solution until
108 one thinks about scaling to larger problems -- i.e., the condition under
109 which TARGET_WEAK_ATTRIBUTE is active will eventually get far too
112 So, we take an approach similar to #pragma weak -- we have a second
113 declaration for functions that we want to have weak references.
115 Neither way is particularly good. */
117 /* References to __register_frame_info and __deregister_frame_info should
118 be weak in this file if at all possible. */
119 extern void __register_frame_info (const void *, struct object *)
120 TARGET_ATTRIBUTE_WEAK;
121 extern void __register_frame_info_bases (const void *, struct object *,
123 TARGET_ATTRIBUTE_WEAK;
124 extern void *__deregister_frame_info (const void *)
125 TARGET_ATTRIBUTE_WEAK;
126 extern void *__deregister_frame_info_bases (const void *)
127 TARGET_ATTRIBUTE_WEAK;
128 extern void __do_global_ctors_1 (void);
130 /* Likewise for _Jv_RegisterClasses. */
131 extern void _Jv_RegisterClasses (void *) TARGET_ATTRIBUTE_WEAK;
133 #ifdef OBJECT_FORMAT_ELF
135 /* Declare a pointer to void function type. */
136 typedef void (*func_ptr) (void);
137 #define STATIC static
139 #else /* OBJECT_FORMAT_ELF */
141 #include "gbl-ctors.h"
145 #endif /* OBJECT_FORMAT_ELF */
149 /* NOTE: In order to be able to support SVR4 shared libraries, we arrange
150 to have one set of symbols { __CTOR_LIST__, __DTOR_LIST__, __CTOR_END__,
151 __DTOR_END__ } per root executable and also one set of these symbols
152 per shared library. So in any given whole process image, we may have
153 multiple definitions of each of these symbols. In order to prevent
154 these definitions from conflicting with one another, and in order to
155 ensure that the proper lists are used for the initialization/finalization
156 of each individual shared library (respectively), we give these symbols
157 only internal (i.e. `static') linkage, and we also make it a point to
158 refer to only the __CTOR_END__ symbol in crtend.o and the __DTOR_LIST__
159 symbol in crtbegin.o, where they are defined. */
161 /* The -1 is a flag to __do_global_[cd]tors indicating that this table
162 does not start with a count of elements. */
163 #ifdef CTOR_LIST_BEGIN
165 #elif defined(CTORS_SECTION_ASM_OP)
166 /* Hack: force cc1 to switch to .data section early, so that assembling
167 __CTOR_LIST__ does not undo our behind-the-back change to .ctors. */
168 static func_ptr force_to_data[1] __attribute__ ((__unused__)) = { };
169 asm (CTORS_SECTION_ASM_OP);
170 STATIC func_ptr __CTOR_LIST__[1]
171 __attribute__ ((__unused__, aligned(sizeof(func_ptr))))
172 = { (func_ptr) (-1) };
174 STATIC func_ptr __CTOR_LIST__[1]
175 __attribute__ ((__unused__, section(".ctors"), aligned(sizeof(func_ptr))))
176 = { (func_ptr) (-1) };
177 #endif /* __CTOR_LIST__ alternatives */
179 #ifdef DTOR_LIST_BEGIN
181 #elif defined(DTORS_SECTION_ASM_OP)
182 asm (DTORS_SECTION_ASM_OP);
183 STATIC func_ptr __DTOR_LIST__[1]
184 __attribute__ ((aligned(sizeof(func_ptr))))
185 = { (func_ptr) (-1) };
187 STATIC func_ptr __DTOR_LIST__[1]
188 __attribute__((section(".dtors"), aligned(sizeof(func_ptr))))
189 = { (func_ptr) (-1) };
190 #endif /* __DTOR_LIST__ alternatives */
192 #ifdef USE_EH_FRAME_REGISTRY
193 /* Stick a label at the beginning of the frame unwind info so we can register
194 and deregister it with the exception handling library code. */
195 STATIC EH_FRAME_SECTION_CONST char __EH_FRAME_BEGIN__[]
196 __attribute__((section(EH_FRAME_SECTION_NAME), aligned(4)))
198 #endif /* USE_EH_FRAME_REGISTRY */
200 #ifdef JCR_SECTION_NAME
201 /* Stick a label at the beginning of the java class registration info
202 so we can register them properly. */
203 STATIC void *__JCR_LIST__[]
204 __attribute__ ((unused, section(JCR_SECTION_NAME), aligned(sizeof(void*))))
206 #endif /* JCR_SECTION_NAME */
208 #if defined(INIT_SECTION_ASM_OP) || defined(INIT_ARRAY_SECTION_ASM_OP)
210 #ifdef OBJECT_FORMAT_ELF
212 /* Declare the __dso_handle variable. It should have a unique value
213 in every shared-object; in a main program its value is zero. The
214 object should in any case be protected. This means the instance
215 in one DSO or the main program is not used in another object. The
216 dynamic linker takes care of this. */
218 #ifdef HAVE_GAS_HIDDEN
219 extern void *__dso_handle __attribute__ ((__visibility__ ("hidden")));
222 void *__dso_handle = &__dso_handle;
224 void *__dso_handle = 0;
227 /* The __cxa_finalize function may not be available so we use only a
229 extern void __cxa_finalize (void *) TARGET_ATTRIBUTE_WEAK;
231 /* Run all the global destructors on exit from the program. */
233 /* Some systems place the number of pointers in the first word of the
234 table. On SVR4 however, that word is -1. In all cases, the table is
235 null-terminated. On SVR4, we start from the beginning of the list and
236 invoke each per-compilation-unit destructor routine in order
237 until we find that null.
239 Note that this function MUST be static. There will be one of these
240 functions in each root executable and one in each shared library, but
241 although they all have the same code, each one is unique in that it
242 refers to one particular associated `__DTOR_LIST__' which belongs to the
243 same particular root executable or shared library file.
245 On some systems, this routine is run more than once from the .fini,
246 when exit is called recursively, so we arrange to remember where in
247 the list we left off processing, and we resume at that point,
248 should we be re-invoked. */
250 static void __attribute__((used))
251 __do_global_dtors_aux (void)
253 #ifndef FINI_ARRAY_SECTION_ASM_OP
254 static func_ptr *p = __DTOR_LIST__ + 1;
256 #endif /* !defined(FINI_ARRAY_SECTION_ASM_OP) */
257 static _Bool completed;
259 if (__builtin_expect (completed, 0))
264 __cxa_finalize (__dso_handle);
267 #ifdef FINI_ARRAY_SECTION_ASM_OP
268 /* If we are using .fini_array then destructors will be run via that
270 #else /* !defined (FINI_ARRAY_SECTION_ASM_OP) */
276 #endif /* !defined(FINI_ARRAY_SECTION_ASM_OP) */
278 #ifdef USE_EH_FRAME_REGISTRY
279 #ifdef CRT_GET_RFIB_DATA
280 /* If we used the new __register_frame_info_bases interface,
281 make sure that we deregister from the same place. */
282 if (__deregister_frame_info_bases)
283 __deregister_frame_info_bases (__EH_FRAME_BEGIN__);
285 if (__deregister_frame_info)
286 __deregister_frame_info (__EH_FRAME_BEGIN__);
293 /* Stick a call to __do_global_dtors_aux into the .fini section. */
294 #ifdef FINI_SECTION_ASM_OP
295 CRT_CALL_STATIC_FUNCTION (FINI_SECTION_ASM_OP, __do_global_dtors_aux)
296 #else /* !defined(FINI_SECTION_ASM_OP) */
297 static func_ptr __do_global_dtors_aux_fini_array_entry[]
298 __attribute__ ((__unused__, section(".fini_array")))
299 = { __do_global_dtors_aux };
300 #endif /* !defined(FINI_SECTION_ASM_OP) */
302 #if defined(USE_EH_FRAME_REGISTRY) || defined(JCR_SECTION_NAME)
303 /* Stick a call to __register_frame_info into the .init section. For some
304 reason calls with no arguments work more reliably in .init, so stick the
305 call in another function. */
307 static void __attribute__((used))
310 #ifdef USE_EH_FRAME_REGISTRY
311 static struct object object;
312 #ifdef CRT_GET_RFIB_DATA
315 CRT_GET_RFIB_DATA (dbase);
316 if (__register_frame_info_bases)
317 __register_frame_info_bases (__EH_FRAME_BEGIN__, &object, tbase, dbase);
319 if (__register_frame_info)
320 __register_frame_info (__EH_FRAME_BEGIN__, &object);
321 #endif /* CRT_GET_RFIB_DATA */
322 #endif /* USE_EH_FRAME_REGISTRY */
323 #ifdef JCR_SECTION_NAME
326 void (*register_classes) (void *) = _Jv_RegisterClasses;
327 __asm ("" : "+r" (register_classes));
328 if (register_classes)
329 register_classes (__JCR_LIST__);
331 #endif /* JCR_SECTION_NAME */
334 #ifdef INIT_SECTION_ASM_OP
335 CRT_CALL_STATIC_FUNCTION (INIT_SECTION_ASM_OP, frame_dummy)
336 #else /* defined(INIT_SECTION_ASM_OP) */
337 static func_ptr __frame_dummy_init_array_entry[]
338 __attribute__ ((__unused__, section(".init_array")))
340 #endif /* !defined(INIT_SECTION_ASM_OP) */
341 #endif /* USE_EH_FRAME_REGISTRY || JCR_SECTION_NAME */
343 #else /* OBJECT_FORMAT_ELF */
345 /* The function __do_global_ctors_aux is compiled twice (once in crtbegin.o
346 and once in crtend.o). It must be declared static to avoid a link
347 error. Here, we define __do_global_ctors as an externally callable
348 function. It is externally callable so that __main can invoke it when
349 INVOKE__main is defined. This has the additional effect of forcing cc1
350 to switch to the .text section. */
352 static void __do_global_ctors_aux (void);
354 __do_global_ctors (void)
357 /* If __main won't actually call __do_global_ctors then it doesn't matter
358 what's inside the function. The inside of __do_global_ctors_aux is
359 called automatically in that case. And the Alliant fx2800 linker
360 crashes on this reference. So prevent the crash. */
361 __do_global_ctors_aux ();
365 asm (INIT_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
367 /* A routine to invoke all of the global constructors upon entry to the
368 program. We put this into the .init section (for systems that have
369 such a thing) so that we can properly perform the construction of
370 file-scope static-storage C++ objects within shared libraries. */
372 static void __attribute__((used))
373 __do_global_ctors_aux (void) /* prologue goes in .init section */
375 FORCE_CODE_SECTION_ALIGN /* explicit align before switch to .text */
376 asm (TEXT_SECTION_ASM_OP); /* don't put epilogue and body in .init */
377 DO_GLOBAL_CTORS_BODY;
378 atexit (__do_global_dtors);
381 #endif /* OBJECT_FORMAT_ELF */
383 #elif defined(HAS_INIT_SECTION) /* ! INIT_SECTION_ASM_OP */
385 extern void __do_global_dtors (void);
387 /* This case is used by the Irix 6 port, which supports named sections but
388 not an SVR4-style .fini section. __do_global_dtors can be non-static
389 in this case because we protect it with -hidden_symbol. */
392 __do_global_dtors (void)
395 for (p = __DTOR_LIST__ + 1; (f = *p); p++)
398 #ifdef USE_EH_FRAME_REGISTRY
399 if (__deregister_frame_info)
400 __deregister_frame_info (__EH_FRAME_BEGIN__);
404 #if defined(USE_EH_FRAME_REGISTRY) || defined(JCR_SECTION_NAME)
405 /* A helper function for __do_global_ctors, which is in crtend.o. Here
406 in crtbegin.o, we can reference a couple of symbols not visible there.
407 Plus, since we're before libgcc.a, we have no problems referencing
408 functions from there. */
410 __do_global_ctors_1(void)
412 #ifdef USE_EH_FRAME_REGISTRY
413 static struct object object;
414 if (__register_frame_info)
415 __register_frame_info (__EH_FRAME_BEGIN__, &object);
417 #ifdef JCR_SECTION_NAME
420 void (*register_classes) (void *) = _Jv_RegisterClasses;
421 __asm ("" : "+r" (register_classes));
422 if (register_classes)
423 register_classes (__JCR_LIST__);
427 #endif /* USE_EH_FRAME_REGISTRY || JCR_SECTION_NAME */
429 #else /* ! INIT_SECTION_ASM_OP && ! HAS_INIT_SECTION */
430 #error "What are you doing with crtstuff.c, then?"
433 #elif defined(CRT_END) /* ! CRT_BEGIN */
435 /* Put a word containing zero at the end of each of our two lists of function
436 addresses. Note that the words defined here go into the .ctors and .dtors
437 sections of the crtend.o file, and since that file is always linked in
438 last, these words naturally end up at the very ends of the two lists
439 contained in these two sections. */
443 #elif defined(CTORS_SECTION_ASM_OP)
444 /* Hack: force cc1 to switch to .data section early, so that assembling
445 __CTOR_LIST__ does not undo our behind-the-back change to .ctors. */
446 static func_ptr force_to_data[1] __attribute__ ((__unused__)) = { };
447 asm (CTORS_SECTION_ASM_OP);
448 STATIC func_ptr __CTOR_END__[1]
449 __attribute__((aligned(sizeof(func_ptr))))
452 STATIC func_ptr __CTOR_END__[1]
453 __attribute__((section(".ctors"), aligned(sizeof(func_ptr))))
459 #elif defined(DTORS_SECTION_ASM_OP)
460 asm (DTORS_SECTION_ASM_OP);
461 STATIC func_ptr __DTOR_END__[1]
462 __attribute__ ((unused, aligned(sizeof(func_ptr))))
465 STATIC func_ptr __DTOR_END__[1]
466 __attribute__((unused, section(".dtors"), aligned(sizeof(func_ptr))))
470 #ifdef EH_FRAME_SECTION_NAME
471 /* Terminate the frame unwind info section with a 4byte 0 as a sentinel;
472 this would be the 'length' field in a real FDE. */
473 # if __INT_MAX__ == 2147483647
475 # elif __LONG_MAX__ == 2147483647
477 # elif __SHRT_MAX__ == 2147483647
480 # error "Missing a 4 byte integer"
482 STATIC EH_FRAME_SECTION_CONST int32 __FRAME_END__[]
483 __attribute__ ((unused, section(EH_FRAME_SECTION_NAME),
484 aligned(sizeof(int32))))
486 #endif /* EH_FRAME_SECTION_NAME */
488 #ifdef JCR_SECTION_NAME
489 /* Null terminate the .jcr section array. */
490 STATIC void *__JCR_END__[1]
491 __attribute__ ((unused, section(JCR_SECTION_NAME),
492 aligned(sizeof(void *))))
494 #endif /* JCR_SECTION_NAME */
496 #ifdef INIT_ARRAY_SECTION_ASM_OP
498 /* If we are using .init_array, there is nothing to do. */
500 #elif defined(INIT_SECTION_ASM_OP)
502 #ifdef OBJECT_FORMAT_ELF
503 static void __attribute__((used))
504 __do_global_ctors_aux (void)
507 for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
511 /* Stick a call to __do_global_ctors_aux into the .init section. */
512 CRT_CALL_STATIC_FUNCTION (INIT_SECTION_ASM_OP, __do_global_ctors_aux)
513 #else /* OBJECT_FORMAT_ELF */
515 /* Stick the real initialization code, followed by a normal sort of
516 function epilogue at the very end of the .init section for this
517 entire root executable file or for this entire shared library file.
519 Note that we use some tricks here to get *just* the body and just
520 a function epilogue (but no function prologue) into the .init
521 section of the crtend.o file. Specifically, we switch to the .text
522 section, start to define a function, and then we switch to the .init
523 section just before the body code.
525 Earlier on, we put the corresponding function prologue into the .init
526 section of the crtbegin.o file (which will be linked in first).
528 Note that we want to invoke all constructors for C++ file-scope static-
529 storage objects AFTER any other possible initialization actions which
530 may be performed by the code in the .init section contributions made by
531 other libraries, etc. That's because those other initializations may
532 include setup operations for very primitive things (e.g. initializing
533 the state of the floating-point coprocessor, etc.) which should be done
534 before we start to execute any of the user's code. */
537 __do_global_ctors_aux (void) /* prologue goes in .text section */
539 asm (INIT_SECTION_ASM_OP);
540 DO_GLOBAL_CTORS_BODY;
541 atexit (__do_global_dtors);
542 } /* epilogue and body go in .init section */
544 FORCE_CODE_SECTION_ALIGN
545 asm (TEXT_SECTION_ASM_OP);
547 #endif /* OBJECT_FORMAT_ELF */
549 #elif defined(HAS_INIT_SECTION) /* ! INIT_SECTION_ASM_OP */
551 extern void __do_global_ctors (void);
553 /* This case is used by the Irix 6 port, which supports named sections but
554 not an SVR4-style .init section. __do_global_ctors can be non-static
555 in this case because we protect it with -hidden_symbol. */
557 __do_global_ctors (void)
560 #if defined(USE_EH_FRAME_REGISTRY) || defined(JCR_SECTION_NAME)
561 __do_global_ctors_1();
563 for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
567 #else /* ! INIT_SECTION_ASM_OP && ! HAS_INIT_SECTION */
568 #error "What are you doing with crtstuff.c, then?"
571 #else /* ! CRT_BEGIN && ! CRT_END */
572 #error "One of CRT_BEGIN or CRT_END must be defined."