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. */
56 #include "coretypes.h"
58 #include "unwind-dw2-fde.h"
60 #ifndef FORCE_CODE_SECTION_ALIGN
61 # define FORCE_CODE_SECTION_ALIGN
64 #ifndef CRT_CALL_STATIC_FUNCTION
65 # define CRT_CALL_STATIC_FUNCTION(SECTION_OP, FUNC) \
66 static void __attribute__((__used__)) \
67 call_ ## FUNC (void) \
71 FORCE_CODE_SECTION_ALIGN \
72 asm (TEXT_SECTION_ASM_OP); \
76 #if defined(OBJECT_FORMAT_ELF) && defined(HAVE_LD_EH_FRAME_HDR) \
77 && !defined(inhibit_libc) && !defined(CRTSTUFFT_O) \
78 && defined(__GLIBC__) && __GLIBC__ >= 2
80 # if (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2) \
81 || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && defined(DT_CONFIG)))
82 # define USE_PT_GNU_EH_FRAME
85 #if defined(EH_FRAME_SECTION_NAME) && !defined(USE_PT_GNU_EH_FRAME)
86 # define USE_EH_FRAME_REGISTRY
88 #if defined(EH_FRAME_SECTION_NAME) && EH_TABLES_CAN_BE_READ_ONLY
89 # define EH_FRAME_SECTION_CONST const
91 # define EH_FRAME_SECTION_CONST
94 /* We do not want to add the weak attribute to the declarations of these
95 routines in unwind-dw2-fde.h because that will cause the definition of
96 these symbols to be weak as well.
98 This exposes a core issue, how to handle creating weak references vs
99 how to create weak definitions. Either we have to have the definition
100 of TARGET_WEAK_ATTRIBUTE be conditional in the shared header files or
101 have a second declaration if we want a function's references to be weak,
102 but not its definition.
104 Making TARGET_WEAK_ATTRIBUTE conditional seems like a good solution until
105 one thinks about scaling to larger problems -- i.e., the condition under
106 which TARGET_WEAK_ATTRIBUTE is active will eventually get far too
109 So, we take an approach similar to #pragma weak -- we have a second
110 declaration for functions that we want to have weak references.
112 Neither way is particularly good. */
114 /* References to __register_frame_info and __deregister_frame_info should
115 be weak in this file if at all possible. */
116 extern void __register_frame_info (const void *, struct object *)
117 TARGET_ATTRIBUTE_WEAK;
118 extern void __register_frame_info_bases (const void *, struct object *,
120 TARGET_ATTRIBUTE_WEAK;
121 extern void *__deregister_frame_info (const void *)
122 TARGET_ATTRIBUTE_WEAK;
123 extern void *__deregister_frame_info_bases (const void *)
124 TARGET_ATTRIBUTE_WEAK;
125 extern void __do_global_ctors_1 (void);
127 /* Likewise for _Jv_RegisterClasses. */
128 extern void _Jv_RegisterClasses (void *) TARGET_ATTRIBUTE_WEAK;
130 #ifdef OBJECT_FORMAT_ELF
132 /* Declare a pointer to void function type. */
133 typedef void (*func_ptr) (void);
134 #define STATIC static
136 #else /* OBJECT_FORMAT_ELF */
138 #include "gbl-ctors.h"
142 #endif /* OBJECT_FORMAT_ELF */
146 /* NOTE: In order to be able to support SVR4 shared libraries, we arrange
147 to have one set of symbols { __CTOR_LIST__, __DTOR_LIST__, __CTOR_END__,
148 __DTOR_END__ } per root executable and also one set of these symbols
149 per shared library. So in any given whole process image, we may have
150 multiple definitions of each of these symbols. In order to prevent
151 these definitions from conflicting with one another, and in order to
152 ensure that the proper lists are used for the initialization/finalization
153 of each individual shared library (respectively), we give these symbols
154 only internal (i.e. `static') linkage, and we also make it a point to
155 refer to only the __CTOR_END__ symbol in crtend.o and the __DTOR_LIST__
156 symbol in crtbegin.o, where they are defined. */
158 /* The -1 is a flag to __do_global_[cd]tors indicating that this table
159 does not start with a count of elements. */
160 #ifdef CTOR_LIST_BEGIN
162 #elif defined(CTORS_SECTION_ASM_OP)
163 /* Hack: force cc1 to switch to .data section early, so that assembling
164 __CTOR_LIST__ does not undo our behind-the-back change to .ctors. */
165 static func_ptr force_to_data[1] __attribute__ ((__unused__)) = { };
166 asm (CTORS_SECTION_ASM_OP);
167 STATIC func_ptr __CTOR_LIST__[1]
168 __attribute__ ((__unused__, aligned(sizeof(func_ptr))))
169 = { (func_ptr) (-1) };
171 STATIC func_ptr __CTOR_LIST__[1]
172 __attribute__ ((__unused__, section(".ctors"), aligned(sizeof(func_ptr))))
173 = { (func_ptr) (-1) };
174 #endif /* __CTOR_LIST__ alternatives */
176 #ifdef DTOR_LIST_BEGIN
178 #elif defined(DTORS_SECTION_ASM_OP)
179 asm (DTORS_SECTION_ASM_OP);
180 STATIC func_ptr __DTOR_LIST__[1]
181 __attribute__ ((aligned(sizeof(func_ptr))))
182 = { (func_ptr) (-1) };
184 STATIC func_ptr __DTOR_LIST__[1]
185 __attribute__((section(".dtors"), aligned(sizeof(func_ptr))))
186 = { (func_ptr) (-1) };
187 #endif /* __DTOR_LIST__ alternatives */
189 #ifdef USE_EH_FRAME_REGISTRY
190 /* Stick a label at the beginning of the frame unwind info so we can register
191 and deregister it with the exception handling library code. */
192 STATIC EH_FRAME_SECTION_CONST char __EH_FRAME_BEGIN__[]
193 __attribute__((section(EH_FRAME_SECTION_NAME), aligned(4)))
195 #endif /* USE_EH_FRAME_REGISTRY */
197 #ifdef JCR_SECTION_NAME
198 /* Stick a label at the beginning of the java class registration info
199 so we can register them properly. */
200 STATIC void *__JCR_LIST__[]
201 __attribute__ ((unused, section(JCR_SECTION_NAME), aligned(sizeof(void*))))
203 #endif /* JCR_SECTION_NAME */
205 #if defined(INIT_SECTION_ASM_OP) || defined(INIT_ARRAY_SECTION_ASM_OP)
207 #ifdef OBJECT_FORMAT_ELF
209 /* Declare the __dso_handle variable. It should have a unique value
210 in every shared-object; in a main program its value is zero. The
211 object should in any case be protected. This means the instance
212 in one DSO or the main program is not used in another object. The
213 dynamic linker takes care of this. */
215 #ifdef HAVE_GAS_HIDDEN
216 extern void *__dso_handle __attribute__ ((__visibility__ ("hidden")));
219 void *__dso_handle = &__dso_handle;
221 void *__dso_handle = 0;
224 /* The __cxa_finalize function may not be available so we use only a
226 extern void __cxa_finalize (void *) TARGET_ATTRIBUTE_WEAK;
228 /* Run all the global destructors on exit from the program. */
230 /* Some systems place the number of pointers in the first word of the
231 table. On SVR4 however, that word is -1. In all cases, the table is
232 null-terminated. On SVR4, we start from the beginning of the list and
233 invoke each per-compilation-unit destructor routine in order
234 until we find that null.
236 Note that this function MUST be static. There will be one of these
237 functions in each root executable and one in each shared library, but
238 although they all have the same code, each one is unique in that it
239 refers to one particular associated `__DTOR_LIST__' which belongs to the
240 same particular root executable or shared library file.
242 On some systems, this routine is run more than once from the .fini,
243 when exit is called recursively, so we arrange to remember where in
244 the list we left off processing, and we resume at that point,
245 should we be re-invoked. */
247 static void __attribute__((used))
248 __do_global_dtors_aux (void)
250 #ifndef FINI_ARRAY_SECTION_ASM_OP
251 static func_ptr *p = __DTOR_LIST__ + 1;
253 #endif /* !defined(FINI_ARRAY_SECTION_ASM_OP) */
254 static _Bool completed;
256 if (__builtin_expect (completed, 0))
261 __cxa_finalize (__dso_handle);
264 #ifdef FINI_ARRAY_SECTION_ASM_OP
265 /* If we are using .fini_array then destructors will be run via that
267 #else /* !defined (FINI_ARRAY_SECTION_ASM_OP) */
273 #endif /* !defined(FINI_ARRAY_SECTION_ASM_OP) */
275 #ifdef USE_EH_FRAME_REGISTRY
276 #ifdef CRT_GET_RFIB_DATA
277 /* If we used the new __register_frame_info_bases interface,
278 make sure that we deregister from the same place. */
279 if (__deregister_frame_info_bases)
280 __deregister_frame_info_bases (__EH_FRAME_BEGIN__);
282 if (__deregister_frame_info)
283 __deregister_frame_info (__EH_FRAME_BEGIN__);
290 /* Stick a call to __do_global_dtors_aux into the .fini section. */
291 #ifdef FINI_SECTION_ASM_OP
292 CRT_CALL_STATIC_FUNCTION (FINI_SECTION_ASM_OP, __do_global_dtors_aux)
293 #else /* !defined(FINI_SECTION_ASM_OP) */
294 static func_ptr __do_global_dtors_aux_fini_array_entry[]
295 __attribute__ ((__unused__, section(".fini_array")))
296 = { __do_global_dtors_aux };
297 #endif /* !defined(FINI_SECTION_ASM_OP) */
299 #if defined(USE_EH_FRAME_REGISTRY) || defined(JCR_SECTION_NAME)
300 /* Stick a call to __register_frame_info into the .init section. For some
301 reason calls with no arguments work more reliably in .init, so stick the
302 call in another function. */
304 static void __attribute__((used))
307 #ifdef USE_EH_FRAME_REGISTRY
308 static struct object object;
309 #ifdef CRT_GET_RFIB_DATA
312 CRT_GET_RFIB_DATA (dbase);
313 if (__register_frame_info_bases)
314 __register_frame_info_bases (__EH_FRAME_BEGIN__, &object, tbase, dbase);
316 if (__register_frame_info)
317 __register_frame_info (__EH_FRAME_BEGIN__, &object);
318 #endif /* CRT_GET_RFIB_DATA */
319 #endif /* USE_EH_FRAME_REGISTRY */
320 #ifdef JCR_SECTION_NAME
323 void (*register_classes) (void *) = _Jv_RegisterClasses;
324 __asm ("" : "+r" (register_classes));
325 if (register_classes)
326 register_classes (__JCR_LIST__);
328 #endif /* JCR_SECTION_NAME */
331 #ifdef INIT_SECTION_ASM_OP
332 CRT_CALL_STATIC_FUNCTION (INIT_SECTION_ASM_OP, frame_dummy)
333 #else /* defined(INIT_SECTION_ASM_OP) */
334 static func_ptr __frame_dummy_init_array_entry[]
335 __attribute__ ((__unused__, section(".init_array")))
337 #endif /* !defined(INIT_SECTION_ASM_OP) */
338 #endif /* USE_EH_FRAME_REGISTRY || JCR_SECTION_NAME */
340 #else /* OBJECT_FORMAT_ELF */
342 /* The function __do_global_ctors_aux is compiled twice (once in crtbegin.o
343 and once in crtend.o). It must be declared static to avoid a link
344 error. Here, we define __do_global_ctors as an externally callable
345 function. It is externally callable so that __main can invoke it when
346 INVOKE__main is defined. This has the additional effect of forcing cc1
347 to switch to the .text section. */
349 static void __do_global_ctors_aux (void);
351 __do_global_ctors (void)
354 /* If __main won't actually call __do_global_ctors then it doesn't matter
355 what's inside the function. The inside of __do_global_ctors_aux is
356 called automatically in that case. And the Alliant fx2800 linker
357 crashes on this reference. So prevent the crash. */
358 __do_global_ctors_aux ();
362 asm (INIT_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
364 /* A routine to invoke all of the global constructors upon entry to the
365 program. We put this into the .init section (for systems that have
366 such a thing) so that we can properly perform the construction of
367 file-scope static-storage C++ objects within shared libraries. */
369 static void __attribute__((used))
370 __do_global_ctors_aux (void) /* prologue goes in .init section */
372 FORCE_CODE_SECTION_ALIGN /* explicit align before switch to .text */
373 asm (TEXT_SECTION_ASM_OP); /* don't put epilogue and body in .init */
374 DO_GLOBAL_CTORS_BODY;
375 atexit (__do_global_dtors);
378 #endif /* OBJECT_FORMAT_ELF */
380 #elif defined(HAS_INIT_SECTION) /* ! INIT_SECTION_ASM_OP */
382 extern void __do_global_dtors (void);
384 /* This case is used by the Irix 6 port, which supports named sections but
385 not an SVR4-style .fini section. __do_global_dtors can be non-static
386 in this case because we protect it with -hidden_symbol. */
389 __do_global_dtors (void)
392 for (p = __DTOR_LIST__ + 1; (f = *p); p++)
395 #ifdef USE_EH_FRAME_REGISTRY
396 if (__deregister_frame_info)
397 __deregister_frame_info (__EH_FRAME_BEGIN__);
401 #if defined(USE_EH_FRAME_REGISTRY) || defined(JCR_SECTION_NAME)
402 /* A helper function for __do_global_ctors, which is in crtend.o. Here
403 in crtbegin.o, we can reference a couple of symbols not visible there.
404 Plus, since we're before libgcc.a, we have no problems referencing
405 functions from there. */
407 __do_global_ctors_1(void)
409 #ifdef USE_EH_FRAME_REGISTRY
410 static struct object object;
411 if (__register_frame_info)
412 __register_frame_info (__EH_FRAME_BEGIN__, &object);
414 #ifdef JCR_SECTION_NAME
417 void (*register_classes) (void *) = _Jv_RegisterClasses;
418 __asm ("" : "+r" (register_classes));
419 if (register_classes)
420 register_classes (__JCR_LIST__);
424 #endif /* USE_EH_FRAME_REGISTRY || JCR_SECTION_NAME */
426 #else /* ! INIT_SECTION_ASM_OP && ! HAS_INIT_SECTION */
427 #error "What are you doing with crtstuff.c, then?"
430 #elif defined(CRT_END) /* ! CRT_BEGIN */
432 /* Put a word containing zero at the end of each of our two lists of function
433 addresses. Note that the words defined here go into the .ctors and .dtors
434 sections of the crtend.o file, and since that file is always linked in
435 last, these words naturally end up at the very ends of the two lists
436 contained in these two sections. */
440 #elif defined(CTORS_SECTION_ASM_OP)
441 /* Hack: force cc1 to switch to .data section early, so that assembling
442 __CTOR_LIST__ does not undo our behind-the-back change to .ctors. */
443 static func_ptr force_to_data[1] __attribute__ ((__unused__)) = { };
444 asm (CTORS_SECTION_ASM_OP);
445 STATIC func_ptr __CTOR_END__[1]
446 __attribute__((aligned(sizeof(func_ptr))))
449 STATIC func_ptr __CTOR_END__[1]
450 __attribute__((section(".ctors"), aligned(sizeof(func_ptr))))
456 #elif defined(DTORS_SECTION_ASM_OP)
457 asm (DTORS_SECTION_ASM_OP);
458 STATIC func_ptr __DTOR_END__[1]
459 __attribute__ ((unused, aligned(sizeof(func_ptr))))
462 STATIC func_ptr __DTOR_END__[1]
463 __attribute__((unused, section(".dtors"), aligned(sizeof(func_ptr))))
467 #ifdef EH_FRAME_SECTION_NAME
468 /* Terminate the frame unwind info section with a 4byte 0 as a sentinel;
469 this would be the 'length' field in a real FDE. */
470 # if __INT_MAX__ == 2147483647
472 # elif __LONG_MAX__ == 2147483647
474 # elif __SHRT_MAX__ == 2147483647
477 # error "Missing a 4 byte integer"
479 STATIC EH_FRAME_SECTION_CONST int32 __FRAME_END__[]
480 __attribute__ ((unused, section(EH_FRAME_SECTION_NAME),
481 aligned(sizeof(int32))))
483 #endif /* EH_FRAME_SECTION_NAME */
485 #ifdef JCR_SECTION_NAME
486 /* Null terminate the .jcr section array. */
487 STATIC void *__JCR_END__[1]
488 __attribute__ ((unused, section(JCR_SECTION_NAME),
489 aligned(sizeof(void *))))
491 #endif /* JCR_SECTION_NAME */
493 #ifdef INIT_ARRAY_SECTION_ASM_OP
495 /* If we are using .init_array, there is nothing to do. */
497 #elif defined(INIT_SECTION_ASM_OP)
499 #ifdef OBJECT_FORMAT_ELF
500 static void __attribute__((used))
501 __do_global_ctors_aux (void)
504 for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
508 /* Stick a call to __do_global_ctors_aux into the .init section. */
509 CRT_CALL_STATIC_FUNCTION (INIT_SECTION_ASM_OP, __do_global_ctors_aux)
510 #else /* OBJECT_FORMAT_ELF */
512 /* Stick the real initialization code, followed by a normal sort of
513 function epilogue at the very end of the .init section for this
514 entire root executable file or for this entire shared library file.
516 Note that we use some tricks here to get *just* the body and just
517 a function epilogue (but no function prologue) into the .init
518 section of the crtend.o file. Specifically, we switch to the .text
519 section, start to define a function, and then we switch to the .init
520 section just before the body code.
522 Earlier on, we put the corresponding function prologue into the .init
523 section of the crtbegin.o file (which will be linked in first).
525 Note that we want to invoke all constructors for C++ file-scope static-
526 storage objects AFTER any other possible initialization actions which
527 may be performed by the code in the .init section contributions made by
528 other libraries, etc. That's because those other initializations may
529 include setup operations for very primitive things (e.g. initializing
530 the state of the floating-point coprocessor, etc.) which should be done
531 before we start to execute any of the user's code. */
534 __do_global_ctors_aux (void) /* prologue goes in .text section */
536 asm (INIT_SECTION_ASM_OP);
537 DO_GLOBAL_CTORS_BODY;
538 atexit (__do_global_dtors);
539 } /* epilogue and body go in .init section */
541 FORCE_CODE_SECTION_ALIGN
542 asm (TEXT_SECTION_ASM_OP);
544 #endif /* OBJECT_FORMAT_ELF */
546 #elif defined(HAS_INIT_SECTION) /* ! INIT_SECTION_ASM_OP */
548 extern void __do_global_ctors (void);
550 /* This case is used by the Irix 6 port, which supports named sections but
551 not an SVR4-style .init section. __do_global_ctors can be non-static
552 in this case because we protect it with -hidden_symbol. */
554 __do_global_ctors (void)
557 #if defined(USE_EH_FRAME_REGISTRY) || defined(JCR_SECTION_NAME)
558 __do_global_ctors_1();
560 for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
564 #else /* ! INIT_SECTION_ASM_OP && ! HAS_INIT_SECTION */
565 #error "What are you doing with crtstuff.c, then?"
568 #else /* ! CRT_BEGIN && ! CRT_END */
569 #error "One of CRT_BEGIN or CRT_END must be defined."