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 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 /* 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
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"
63 #include "unwind-dw2-fde.h"
65 #ifndef FORCE_CODE_SECTION_ALIGN
66 # define FORCE_CODE_SECTION_ALIGN
69 #ifndef CRT_CALL_STATIC_FUNCTION
70 # define CRT_CALL_STATIC_FUNCTION(SECTION_OP, FUNC) \
71 static void __attribute__((__used__)) \
72 call_ ## FUNC (void) \
76 FORCE_CODE_SECTION_ALIGN \
77 asm (TEXT_SECTION_ASM_OP); \
81 #if defined(OBJECT_FORMAT_ELF) && defined(HAVE_LD_EH_FRAME_HDR) \
82 && !defined(inhibit_libc) && !defined(CRTSTUFFT_O) \
83 && defined(__GLIBC__) && __GLIBC__ >= 2
85 # if (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2) \
86 || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && defined(DT_CONFIG)))
87 # define USE_PT_GNU_EH_FRAME
90 #if defined(EH_FRAME_SECTION_NAME) && !defined(USE_PT_GNU_EH_FRAME)
91 # define USE_EH_FRAME_REGISTRY
93 #if defined(EH_FRAME_SECTION_NAME) && defined(HAVE_LD_RO_RW_SECTION_MIXING)
94 # define EH_FRAME_SECTION_CONST const
96 # define EH_FRAME_SECTION_CONST
99 /* We do not want to add the weak attribute to the declarations of these
100 routines in unwind-dw2-fde.h because that will cause the definition of
101 these symbols to be weak as well.
103 This exposes a core issue, how to handle creating weak references vs
104 how to create weak definitions. Either we have to have the definition
105 of TARGET_WEAK_ATTRIBUTE be conditional in the shared header files or
106 have a second declaration if we want a function's references to be weak,
107 but not its definition.
109 Making TARGET_WEAK_ATTRIBUTE conditional seems like a good solution until
110 one thinks about scaling to larger problems -- ie, the condition under
111 which TARGET_WEAK_ATTRIBUTE is active will eventually get far too
114 So, we take an approach similar to #pragma weak -- we have a second
115 declaration for functions that we want to have weak references.
117 Neither way is particularly good. */
119 /* References to __register_frame_info and __deregister_frame_info should
120 be weak in this file if at all possible. */
121 extern void __register_frame_info (void *, struct object
*)
122 TARGET_ATTRIBUTE_WEAK
;
123 extern void __register_frame_info_bases (void *, struct object
*,
125 TARGET_ATTRIBUTE_WEAK
;
126 extern void *__deregister_frame_info (void *)
127 TARGET_ATTRIBUTE_WEAK
;
128 extern void *__deregister_frame_info_bases (void *)
129 TARGET_ATTRIBUTE_WEAK
;
131 /* Likewise for _Jv_RegisterClasses. */
132 extern void _Jv_RegisterClasses (void *) TARGET_ATTRIBUTE_WEAK
;
134 #ifdef OBJECT_FORMAT_ELF
136 /* Declare a pointer to void function type. */
137 typedef void (*func_ptr
) (void);
138 #define STATIC static
140 #else /* OBJECT_FORMAT_ELF */
142 #include "gbl-ctors.h"
146 #endif /* OBJECT_FORMAT_ELF */
150 /* NOTE: In order to be able to support SVR4 shared libraries, we arrange
151 to have one set of symbols { __CTOR_LIST__, __DTOR_LIST__, __CTOR_END__,
152 __DTOR_END__ } per root executable and also one set of these symbols
153 per shared library. So in any given whole process image, we may have
154 multiple definitions of each of these symbols. In order to prevent
155 these definitions from conflicting with one another, and in order to
156 ensure that the proper lists are used for the initialization/finalization
157 of each individual shared library (respectively), we give these symbols
158 only internal (i.e. `static') linkage, and we also make it a point to
159 refer to only the __CTOR_END__ symbol in crtend.o and the __DTOR_LIST__
160 symbol in crtbegin.o, where they are defined. */
162 /* The -1 is a flag to __do_global_[cd]tors indicating that this table
163 does not start with a count of elements. */
164 #ifdef CTOR_LIST_BEGIN
166 #elif defined(CTORS_SECTION_ASM_OP)
167 /* Hack: force cc1 to switch to .data section early, so that assembling
168 __CTOR_LIST__ does not undo our behind-the-back change to .ctors. */
169 static func_ptr force_to_data
[1] __attribute__ ((__unused__
)) = { };
170 asm (CTORS_SECTION_ASM_OP
);
171 STATIC func_ptr __CTOR_LIST__
[1]
172 __attribute__ ((__unused__
, aligned(sizeof(func_ptr
))))
173 = { (func_ptr
) (-1) };
175 STATIC func_ptr __CTOR_LIST__
[1]
176 __attribute__ ((__unused__
, section(".ctors"), aligned(sizeof(func_ptr
))))
177 = { (func_ptr
) (-1) };
178 #endif /* __CTOR_LIST__ alternatives */
180 #ifdef DTOR_LIST_BEGIN
182 #elif defined(DTORS_SECTION_ASM_OP)
183 asm (DTORS_SECTION_ASM_OP
);
184 STATIC func_ptr __DTOR_LIST__
[1]
185 __attribute__ ((aligned(sizeof(func_ptr
))))
186 = { (func_ptr
) (-1) };
188 STATIC func_ptr __DTOR_LIST__
[1]
189 __attribute__((section(".dtors"), aligned(sizeof(func_ptr
))))
190 = { (func_ptr
) (-1) };
191 #endif /* __DTOR_LIST__ alternatives */
193 #ifdef USE_EH_FRAME_REGISTRY
194 /* Stick a label at the beginning of the frame unwind info so we can register
195 and deregister it with the exception handling library code. */
196 STATIC EH_FRAME_SECTION_CONST
char __EH_FRAME_BEGIN__
[]
197 __attribute__((section(EH_FRAME_SECTION_NAME
), aligned(4)))
199 #endif /* USE_EH_FRAME_REGISTRY */
201 #ifdef JCR_SECTION_NAME
202 /* Stick a label at the beginning of the java class registration info
203 so we can register them properly. */
204 STATIC
void *__JCR_LIST__
[]
205 __attribute__ ((unused
, section(JCR_SECTION_NAME
), aligned(sizeof(void*))))
207 #endif /* JCR_SECTION_NAME */
209 #ifdef INIT_SECTION_ASM_OP
211 #ifdef OBJECT_FORMAT_ELF
213 /* Declare the __dso_handle variable. It should have a unique value
214 in every shared-object; in a main program its value is zero. The
215 object should in any case be protected. This means the instance
216 in one DSO or the main program is not used in another object. The
217 dynamic linker takes care of this. */
219 #ifdef HAVE_GAS_HIDDEN
220 extern void *__dso_handle
__attribute__ ((__visibility__ ("hidden")));
223 void *__dso_handle
= &__dso_handle
;
225 void *__dso_handle
= 0;
228 /* The __cxa_finalize function may not be available so we use only a
230 extern void __cxa_finalize (void *) TARGET_ATTRIBUTE_WEAK
;
232 /* Run all the global destructors on exit from the program. */
234 /* Some systems place the number of pointers in the first word of the
235 table. On SVR4 however, that word is -1. In all cases, the table is
236 null-terminated. On SVR4, we start from the beginning of the list and
237 invoke each per-compilation-unit destructor routine in order
238 until we find that null.
240 Note that this function MUST be static. There will be one of these
241 functions in each root executable and one in each shared library, but
242 although they all have the same code, each one is unique in that it
243 refers to one particular associated `__DTOR_LIST__' which belongs to the
244 same particular root executable or shared library file.
246 On some systems, this routine is run more than once from the .fini,
247 when exit is called recursively, so we arrange to remember where in
248 the list we left off processing, and we resume at that point,
249 should we be re-invoked. */
251 static void __attribute__((used
))
252 __do_global_dtors_aux (void)
254 static func_ptr
*p
= __DTOR_LIST__
+ 1;
255 static _Bool completed
;
258 if (__builtin_expect (completed
, 0))
263 __cxa_finalize (__dso_handle
);
272 #ifdef USE_EH_FRAME_REGISTRY
273 #if defined(CRT_GET_RFIB_TEXT) || defined(CRT_GET_RFIB_DATA)
274 /* If we used the new __register_frame_info_bases interface,
275 make sure that we deregister from the same place. */
276 if (__deregister_frame_info_bases
)
277 __deregister_frame_info_bases (__EH_FRAME_BEGIN__
);
279 if (__deregister_frame_info
)
280 __deregister_frame_info (__EH_FRAME_BEGIN__
);
287 /* Stick a call to __do_global_dtors_aux into the .fini section. */
288 CRT_CALL_STATIC_FUNCTION (FINI_SECTION_ASM_OP
, __do_global_dtors_aux
)
290 #if defined(USE_EH_FRAME_REGISTRY) || defined(JCR_SECTION_NAME)
291 /* Stick a call to __register_frame_info into the .init section. For some
292 reason calls with no arguments work more reliably in .init, so stick the
293 call in another function. */
295 static void __attribute__((used
))
298 #ifdef USE_EH_FRAME_REGISTRY
299 static struct object object
;
300 #if defined(CRT_GET_RFIB_TEXT) || defined(CRT_GET_RFIB_DATA)
302 #ifdef CRT_GET_RFIB_TEXT
303 CRT_GET_RFIB_TEXT (tbase
);
307 #ifdef CRT_GET_RFIB_DATA
308 CRT_GET_RFIB_DATA (dbase
);
312 if (__register_frame_info_bases
)
313 __register_frame_info_bases (__EH_FRAME_BEGIN__
, &object
, tbase
, dbase
);
315 if (__register_frame_info
)
316 __register_frame_info (__EH_FRAME_BEGIN__
, &object
);
318 #endif /* USE_EH_FRAME_REGISTRY */
319 #ifdef JCR_SECTION_NAME
320 if (__JCR_LIST__
[0] && _Jv_RegisterClasses
)
321 _Jv_RegisterClasses (__JCR_LIST__
);
322 #endif /* JCR_SECTION_NAME */
325 CRT_CALL_STATIC_FUNCTION (INIT_SECTION_ASM_OP
, frame_dummy
)
326 #endif /* USE_EH_FRAME_REGISTRY || JCR_SECTION_NAME */
328 #else /* OBJECT_FORMAT_ELF */
330 /* The function __do_global_ctors_aux is compiled twice (once in crtbegin.o
331 and once in crtend.o). It must be declared static to avoid a link
332 error. Here, we define __do_global_ctors as an externally callable
333 function. It is externally callable so that __main can invoke it when
334 INVOKE__main is defined. This has the additional effect of forcing cc1
335 to switch to the .text section. */
337 static void __do_global_ctors_aux (void);
339 __do_global_ctors (void)
342 /* If __main won't actually call __do_global_ctors then it doesn't matter
343 what's inside the function. The inside of __do_global_ctors_aux is
344 called automatically in that case. And the Alliant fx2800 linker
345 crashes on this reference. So prevent the crash. */
346 __do_global_ctors_aux ();
350 asm (INIT_SECTION_ASM_OP
); /* cc1 doesn't know that we are switching! */
352 /* On some svr4 systems, the initial .init section preamble code provided in
353 crti.o may do something, such as bump the stack, which we have to
354 undo before we reach the function prologue code for __do_global_ctors
355 (directly below). For such systems, define the macro INIT_SECTION_PREAMBLE
356 to expand into the code needed to undo the actions of the crti.o file. */
358 #ifdef INIT_SECTION_PREAMBLE
359 INIT_SECTION_PREAMBLE
;
362 /* A routine to invoke all of the global constructors upon entry to the
363 program. We put this into the .init section (for systems that have
364 such a thing) so that we can properly perform the construction of
365 file-scope static-storage C++ objects within shared libraries. */
367 static void __attribute__((used
))
368 __do_global_ctors_aux (void) /* prologue goes in .init section */
370 FORCE_CODE_SECTION_ALIGN
/* explicit align before switch to .text */
371 asm (TEXT_SECTION_ASM_OP
); /* don't put epilogue and body in .init */
372 DO_GLOBAL_CTORS_BODY
;
373 atexit (__do_global_dtors
);
376 #endif /* OBJECT_FORMAT_ELF */
378 #elif defined(HAS_INIT_SECTION) /* ! INIT_SECTION_ASM_OP */
380 /* This case is used by the Irix 6 port, which supports named sections but
381 not an SVR4-style .fini section. __do_global_dtors can be non-static
382 in this case because we protect it with -hidden_symbol. */
385 __do_global_dtors (void)
388 for (p
= __DTOR_LIST__
+ 1; (f
= *p
); p
++)
391 #ifdef USE_EH_FRAME_REGISTRY
392 if (__deregister_frame_info
)
393 __deregister_frame_info (__EH_FRAME_BEGIN__
);
397 #if defined(USE_EH_FRAME_REGISTRY) || defined(JCR_SECTION_NAME)
398 /* A helper function for __do_global_ctors, which is in crtend.o. Here
399 in crtbegin.o, we can reference a couple of symbols not visible there.
400 Plus, since we're before libgcc.a, we have no problems referencing
401 functions from there. */
403 __do_global_ctors_1(void)
405 #ifdef USE_EH_FRAME_REGISTRY
406 static struct object object
;
407 if (__register_frame_info
)
408 __register_frame_info (__EH_FRAME_BEGIN__
, &object
);
410 #ifdef JCR_SECTION_NAME
411 if (__JCR_LIST__
[0] && _Jv_RegisterClasses
)
412 _Jv_RegisterClasses (__JCR_LIST__
);
415 #endif /* USE_EH_FRAME_REGISTRY || JCR_SECTION_NAME */
417 #else /* ! INIT_SECTION_ASM_OP && ! HAS_INIT_SECTION */
418 #error "What are you doing with crtstuff.c, then?"
421 #elif defined(CRT_END) /* ! CRT_BEGIN */
423 /* Put a word containing zero at the end of each of our two lists of function
424 addresses. Note that the words defined here go into the .ctors and .dtors
425 sections of the crtend.o file, and since that file is always linked in
426 last, these words naturally end up at the very ends of the two lists
427 contained in these two sections. */
431 #elif defined(CTORS_SECTION_ASM_OP)
432 /* Hack: force cc1 to switch to .data section early, so that assembling
433 __CTOR_LIST__ does not undo our behind-the-back change to .ctors. */
434 static func_ptr force_to_data
[1] __attribute__ ((__unused__
)) = { };
435 asm (CTORS_SECTION_ASM_OP
);
436 STATIC func_ptr __CTOR_END__
[1]
437 __attribute__((aligned(sizeof(func_ptr
))))
440 STATIC func_ptr __CTOR_END__
[1]
441 __attribute__((section(".ctors"), aligned(sizeof(func_ptr
))))
447 #elif defined(DTORS_SECTION_ASM_OP)
448 asm (DTORS_SECTION_ASM_OP
);
449 STATIC func_ptr __DTOR_END__
[1]
450 __attribute__ ((unused
, aligned(sizeof(func_ptr
))))
453 STATIC func_ptr __DTOR_END__
[1]
454 __attribute__((unused
, section(".dtors"), aligned(sizeof(func_ptr
))))
458 #ifdef EH_FRAME_SECTION_NAME
459 /* Terminate the frame unwind info section with a 4byte 0 as a sentinel;
460 this would be the 'length' field in a real FDE. */
461 STATIC EH_FRAME_SECTION_CONST
int __FRAME_END__
[]
462 __attribute__ ((unused
, mode(SI
), section(EH_FRAME_SECTION_NAME
),
465 #endif /* EH_FRAME_SECTION_NAME */
467 #ifdef JCR_SECTION_NAME
468 /* Null terminate the .jcr section array. */
469 STATIC
void *__JCR_END__
[1]
470 __attribute__ ((unused
, section(JCR_SECTION_NAME
),
471 aligned(sizeof(void *))))
473 #endif /* JCR_SECTION_NAME */
475 #ifdef INIT_SECTION_ASM_OP
477 #ifdef OBJECT_FORMAT_ELF
478 static void __attribute__((used
))
479 __do_global_ctors_aux (void)
482 for (p
= __CTOR_END__
- 1; *p
!= (func_ptr
) -1; p
--)
486 /* Stick a call to __do_global_ctors_aux into the .init section. */
487 CRT_CALL_STATIC_FUNCTION (INIT_SECTION_ASM_OP
, __do_global_ctors_aux
)
488 #else /* OBJECT_FORMAT_ELF */
490 /* Stick the real initialization code, followed by a normal sort of
491 function epilogue at the very end of the .init section for this
492 entire root executable file or for this entire shared library file.
494 Note that we use some tricks here to get *just* the body and just
495 a function epilogue (but no function prologue) into the .init
496 section of the crtend.o file. Specifically, we switch to the .text
497 section, start to define a function, and then we switch to the .init
498 section just before the body code.
500 Earlier on, we put the corresponding function prologue into the .init
501 section of the crtbegin.o file (which will be linked in first).
503 Note that we want to invoke all constructors for C++ file-scope static-
504 storage objects AFTER any other possible initialization actions which
505 may be performed by the code in the .init section contributions made by
506 other libraries, etc. That's because those other initializations may
507 include setup operations for very primitive things (e.g. initializing
508 the state of the floating-point coprocessor, etc.) which should be done
509 before we start to execute any of the user's code. */
512 __do_global_ctors_aux (void) /* prologue goes in .text section */
514 asm (INIT_SECTION_ASM_OP
);
515 DO_GLOBAL_CTORS_BODY
;
516 atexit (__do_global_dtors
);
517 } /* epilogue and body go in .init section */
519 FORCE_CODE_SECTION_ALIGN
520 asm (TEXT_SECTION_ASM_OP
);
522 #endif /* OBJECT_FORMAT_ELF */
524 #elif defined(HAS_INIT_SECTION) /* ! INIT_SECTION_ASM_OP */
526 /* This case is used by the Irix 6 port, which supports named sections but
527 not an SVR4-style .init section. __do_global_ctors can be non-static
528 in this case because we protect it with -hidden_symbol. */
529 extern void __do_global_ctors_1(void);
531 __do_global_ctors (void)
534 #if defined(USE_EH_FRAME_REGISTRY) || defined(JCR_SECTION_NAME)
535 __do_global_ctors_1();
537 for (p
= __CTOR_END__
- 1; *p
!= (func_ptr
) -1; p
--)
541 #else /* ! INIT_SECTION_ASM_OP && ! HAS_INIT_SECTION */
542 #error "What are you doing with crtstuff.c, then?"
545 #else /* ! CRT_BEGIN && ! CRT_END */
546 #error "One of CRT_BEGIN or CRT_END must be defined."