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9d13f5c4 | 1 | /* Specialized bits of code needed to support construction and |
2 | destruction of file-scope objects in C++ code. | |
72ac783d | 3 | Copyright (C) 1991, 94-97, 1998 Free Software Foundation, Inc. |
31dcf09a | 4 | Contributed by Ron Guilmette (rfg@monkeys.com). |
9d13f5c4 | 5 | |
6 | This file is part of GNU CC. | |
7 | ||
8 | GNU CC is free software; you can redistribute it and/or modify | |
9 | it under the terms of the GNU General Public License as published by | |
10 | the Free Software Foundation; either version 2, or (at your option) | |
11 | any later version. | |
12 | ||
13 | GNU CC is distributed in the hope that it will be useful, | |
14 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | GNU General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
19 | along with GNU CC; see the file COPYING. If not, write to | |
8d62a21c | 20 | the Free Software Foundation, 59 Temple Place - Suite 330, |
21 | Boston, MA 02111-1307, USA. */ | |
9d13f5c4 | 22 | |
23 | /* As a special exception, if you link this library with files | |
24 | compiled with GCC to produce an executable, this does not cause | |
25 | the resulting executable to be covered by the GNU General Public License. | |
26 | This exception does not however invalidate any other reasons why | |
27 | the executable file might be covered by the GNU General Public License. */ | |
28 | ||
29 | /* This file is a bit like libgcc1.c/libgcc2.c in that it is compiled | |
30 | multiple times and yields multiple .o files. | |
31 | ||
32 | This file is useful on target machines where the object file format | |
33 | supports multiple "user-defined" sections (e.g. COFF, ELF, ROSE). On | |
34 | such systems, this file allows us to avoid running collect (or any | |
35 | other such slow and painful kludge). Additionally, if the target | |
36 | system supports a .init section, this file allows us to support the | |
37 | linking of C++ code with a non-C++ main program. | |
38 | ||
39 | Note that if INIT_SECTION_ASM_OP is defined in the tm.h file, then | |
40 | this file *will* make use of the .init section. If that symbol is | |
41 | not defined however, then the .init section will not be used. | |
42 | ||
5dd605c6 | 43 | Currently, only ELF and COFF are supported. It is likely however that |
44 | ROSE could also be supported, if someone was willing to do the work to | |
45 | make whatever (small?) adaptations are needed. (Some work may be | |
46 | needed on the ROSE assembler and linker also.) | |
9d13f5c4 | 47 | |
48 | This file must be compiled with gcc. */ | |
49 | ||
50 | /* It is incorrect to include config.h here, because this file is being | |
51 | compiled for the target, and hence definitions concerning only the host | |
52 | do not apply. */ | |
53 | ||
54 | #include "tm.h" | |
d757b8c9 | 55 | #include "defaults.h" |
ad87de1e | 56 | #include <stddef.h> |
57 | #include "frame.h" | |
9d13f5c4 | 58 | |
b7c87ff2 | 59 | /* Provide default definitions for the pseudo-ops used to switch to the |
60 | .ctors and .dtors sections. | |
61 | ||
62 | Note that we want to give these sections the SHF_WRITE attribute | |
63 | because these sections will actually contain data (i.e. tables of | |
64 | addresses of functions in the current root executable or shared library | |
65 | file) and, in the case of a shared library, the relocatable addresses | |
66 | will have to be properly resolved/relocated (and then written into) by | |
67 | the dynamic linker when it actually attaches the given shared library | |
68 | to the executing process. (Note that on SVR4, you may wish to use the | |
69 | `-z text' option to the ELF linker, when building a shared library, as | |
70 | an additional check that you are doing everything right. But if you do | |
71 | use the `-z text' option when building a shared library, you will get | |
72 | errors unless the .ctors and .dtors sections are marked as writable | |
73 | via the SHF_WRITE attribute.) */ | |
74 | ||
9d13f5c4 | 75 | #ifndef CTORS_SECTION_ASM_OP |
b7c87ff2 | 76 | #define CTORS_SECTION_ASM_OP ".section\t.ctors,\"aw\"" |
9d13f5c4 | 77 | #endif |
78 | #ifndef DTORS_SECTION_ASM_OP | |
b7c87ff2 | 79 | #define DTORS_SECTION_ASM_OP ".section\t.dtors,\"aw\"" |
9d13f5c4 | 80 | #endif |
d757b8c9 | 81 | #if !defined (EH_FRAME_SECTION_ASM_OP) && defined (DWARF2_UNWIND_INFO) && defined(ASM_OUTPUT_SECTION_NAME) |
82 | #define EH_FRAME_SECTION_ASM_OP ".section\t.eh_frame,\"aw\"" | |
83 | #endif | |
9d13f5c4 | 84 | |
b7c87ff2 | 85 | #ifdef OBJECT_FORMAT_ELF |
86 | ||
87 | /* Declare a pointer to void function type. */ | |
88 | typedef void (*func_ptr) (void); | |
89 | #define STATIC static | |
90 | ||
91 | #else /* OBJECT_FORMAT_ELF */ | |
92 | ||
9d13f5c4 | 93 | #include "gbl-ctors.h" |
94 | ||
95 | #ifndef ON_EXIT | |
96 | #define ON_EXIT(a, b) | |
97 | #endif | |
b7c87ff2 | 98 | #define STATIC |
99 | ||
100 | #endif /* OBJECT_FORMAT_ELF */ | |
9d13f5c4 | 101 | |
102 | #ifdef CRT_BEGIN | |
103 | ||
104 | #ifdef INIT_SECTION_ASM_OP | |
105 | ||
b7c87ff2 | 106 | #ifdef OBJECT_FORMAT_ELF |
107 | ||
108 | /* Run all the global destructors on exit from the program. */ | |
109 | ||
110 | /* Some systems place the number of pointers in the first word of the | |
111 | table. On SVR4 however, that word is -1. In all cases, the table is | |
112 | null-terminated. On SVR4, we start from the beginning of the list and | |
113 | invoke each per-compilation-unit destructor routine in order | |
114 | until we find that null. | |
115 | ||
116 | Note that this function MUST be static. There will be one of these | |
117 | functions in each root executable and one in each shared library, but | |
118 | although they all have the same code, each one is unique in that it | |
119 | refers to one particular associated `__DTOR_LIST__' which belongs to the | |
113f9ca7 | 120 | same particular root executable or shared library file. |
121 | ||
122 | On some systems, this routine is run more than once from the .fini, | |
123 | when exit is called recursively, so we arrange to remember where in | |
124 | the list we left off processing, and we resume at that point, | |
125 | should we be re-invoked. */ | |
b7c87ff2 | 126 | |
d757b8c9 | 127 | static char __EH_FRAME_BEGIN__[]; |
b7c87ff2 | 128 | static func_ptr __DTOR_LIST__[]; |
129 | static void | |
130 | __do_global_dtors_aux () | |
131 | { | |
113f9ca7 | 132 | static func_ptr *p = __DTOR_LIST__ + 1; |
dade0711 | 133 | static int completed = 0; |
134 | ||
135 | if (completed) | |
136 | return; | |
137 | ||
113f9ca7 | 138 | while (*p) |
139 | { | |
140 | p++; | |
141 | (*(p-1)) (); | |
142 | } | |
d757b8c9 | 143 | |
144 | #ifdef EH_FRAME_SECTION_ASM_OP | |
c4fa4c4d | 145 | __deregister_frame_info (__EH_FRAME_BEGIN__); |
d757b8c9 | 146 | #endif |
dade0711 | 147 | completed = 1; |
b7c87ff2 | 148 | } |
149 | ||
dade0711 | 150 | |
b7c87ff2 | 151 | /* Stick a call to __do_global_dtors_aux into the .fini section. */ |
a92771b8 | 152 | |
b7c87ff2 | 153 | static void |
154 | fini_dummy () | |
155 | { | |
156 | asm (FINI_SECTION_ASM_OP); | |
157 | __do_global_dtors_aux (); | |
158 | #ifdef FORCE_FINI_SECTION_ALIGN | |
159 | FORCE_FINI_SECTION_ALIGN; | |
160 | #endif | |
161 | asm (TEXT_SECTION_ASM_OP); | |
162 | } | |
163 | ||
d757b8c9 | 164 | #ifdef EH_FRAME_SECTION_ASM_OP |
c4fa4c4d | 165 | /* Stick a call to __register_frame_info into the .init section. For some |
166 | reason calls with no arguments work more reliably in .init, so stick the | |
167 | call in another function. */ | |
d757b8c9 | 168 | |
169 | static void | |
170 | frame_dummy () | |
171 | { | |
ad87de1e | 172 | static struct object object; |
c4fa4c4d | 173 | __register_frame_info (__EH_FRAME_BEGIN__, &object); |
d757b8c9 | 174 | } |
175 | ||
176 | static void | |
177 | init_dummy () | |
178 | { | |
179 | asm (INIT_SECTION_ASM_OP); | |
180 | frame_dummy (); | |
181 | #ifdef FORCE_INIT_SECTION_ALIGN | |
182 | FORCE_INIT_SECTION_ALIGN; | |
183 | #endif | |
184 | asm (TEXT_SECTION_ASM_OP); | |
185 | } | |
186 | #endif /* EH_FRAME_SECTION_ASM_OP */ | |
187 | ||
b7c87ff2 | 188 | #else /* OBJECT_FORMAT_ELF */ |
189 | ||
b13ae905 | 190 | /* The function __do_global_ctors_aux is compiled twice (once in crtbegin.o |
d8fa92ab | 191 | and once in crtend.o). It must be declared static to avoid a link |
b13ae905 | 192 | error. Here, we define __do_global_ctors as an externally callable |
193 | function. It is externally callable so that __main can invoke it when | |
194 | INVOKE__main is defined. This has the additional effect of forcing cc1 | |
195 | to switch to the .text section. */ | |
a92771b8 | 196 | |
ee45242a | 197 | static void __do_global_ctors_aux (); |
84b64a19 | 198 | void __do_global_ctors () |
199 | { | |
200 | #ifdef INVOKE__main /* If __main won't actually call __do_global_ctors | |
201 | then it doesn't matter what's inside the function. | |
202 | The inside of __do_global_ctors_aux is called | |
203 | automatically in that case. | |
204 | And the Alliant fx2800 linker crashes | |
205 | on this reference. So prevent the crash. */ | |
206 | __do_global_ctors_aux (); | |
207 | #endif | |
208 | } | |
9d13f5c4 | 209 | |
210 | asm (INIT_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ | |
211 | ||
3c67709e | 212 | /* On some svr4 systems, the initial .init section preamble code provided in |
213 | crti.o may do something, such as bump the stack, which we have to | |
214 | undo before we reach the function prologue code for __do_global_ctors | |
215 | (directly below). For such systems, define the macro INIT_SECTION_PREAMBLE | |
a92771b8 | 216 | to expand into the code needed to undo the actions of the crti.o file. */ |
3c67709e | 217 | |
218 | #ifdef INIT_SECTION_PREAMBLE | |
219 | INIT_SECTION_PREAMBLE; | |
220 | #endif | |
221 | ||
9d13f5c4 | 222 | /* A routine to invoke all of the global constructors upon entry to the |
223 | program. We put this into the .init section (for systems that have | |
224 | such a thing) so that we can properly perform the construction of | |
225 | file-scope static-storage C++ objects within shared libraries. */ | |
226 | ||
227 | static void | |
b13ae905 | 228 | __do_global_ctors_aux () /* prologue goes in .init section */ |
9d13f5c4 | 229 | { |
635d52b7 | 230 | #ifdef FORCE_INIT_SECTION_ALIGN |
231 | FORCE_INIT_SECTION_ALIGN; /* Explicit align before switch to .text */ | |
232 | #endif | |
9d13f5c4 | 233 | asm (TEXT_SECTION_ASM_OP); /* don't put epilogue and body in .init */ |
234 | DO_GLOBAL_CTORS_BODY; | |
235 | ON_EXIT (__do_global_dtors, 0); | |
236 | } | |
237 | ||
b7c87ff2 | 238 | #endif /* OBJECT_FORMAT_ELF */ |
8313a782 | 239 | |
240 | #else /* defined(INIT_SECTION_ASM_OP) */ | |
241 | ||
4e04a2df | 242 | #ifdef HAS_INIT_SECTION |
8313a782 | 243 | /* This case is used by the Irix 6 port, which supports named sections but |
244 | not an SVR4-style .fini section. __do_global_dtors can be non-static | |
d757b8c9 | 245 | in this case because we protect it with -hidden_symbol. */ |
246 | ||
247 | static char __EH_FRAME_BEGIN__[]; | |
8313a782 | 248 | static func_ptr __DTOR_LIST__[]; |
249 | void | |
250 | __do_global_dtors () | |
251 | { | |
252 | func_ptr *p; | |
253 | for (p = __DTOR_LIST__ + 1; *p; p++) | |
254 | (*p) (); | |
d757b8c9 | 255 | |
256 | #ifdef EH_FRAME_SECTION_ASM_OP | |
c4fa4c4d | 257 | __deregister_frame_info (__EH_FRAME_BEGIN__); |
d757b8c9 | 258 | #endif |
8313a782 | 259 | } |
72ac783d | 260 | |
261 | #ifdef EH_FRAME_SECTION_ASM_OP | |
262 | /* Define a function here to call __register_frame. crtend.o is linked in | |
263 | after libgcc.a, and hence can't call libgcc.a functions directly. That | |
264 | can lead to unresolved function references. */ | |
265 | void | |
266 | __frame_dummy () | |
267 | { | |
268 | static struct object object; | |
269 | __register_frame_info (__EH_FRAME_BEGIN__, &object); | |
270 | } | |
271 | #endif | |
4e04a2df | 272 | #endif |
8313a782 | 273 | |
9d13f5c4 | 274 | #endif /* defined(INIT_SECTION_ASM_OP) */ |
275 | ||
276 | /* Force cc1 to switch to .data section. */ | |
277 | static func_ptr force_to_data[0] = { }; | |
278 | ||
b7c87ff2 | 279 | /* NOTE: In order to be able to support SVR4 shared libraries, we arrange |
280 | to have one set of symbols { __CTOR_LIST__, __DTOR_LIST__, __CTOR_END__, | |
281 | __DTOR_END__ } per root executable and also one set of these symbols | |
282 | per shared library. So in any given whole process image, we may have | |
283 | multiple definitions of each of these symbols. In order to prevent | |
284 | these definitions from conflicting with one another, and in order to | |
285 | ensure that the proper lists are used for the initialization/finalization | |
286 | of each individual shared library (respectively), we give these symbols | |
287 | only internal (i.e. `static') linkage, and we also make it a point to | |
288 | refer to only the __CTOR_END__ symbol in crtend.o and the __DTOR_LIST__ | |
289 | symbol in crtbegin.o, where they are defined. */ | |
290 | ||
9d13f5c4 | 291 | /* The -1 is a flag to __do_global_[cd]tors |
292 | indicating that this table does not start with a count of elements. */ | |
b13ae905 | 293 | #ifdef CTOR_LIST_BEGIN |
294 | CTOR_LIST_BEGIN; | |
295 | #else | |
9d13f5c4 | 296 | asm (CTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ |
b7c87ff2 | 297 | STATIC func_ptr __CTOR_LIST__[1] = { (func_ptr) (-1) }; |
b13ae905 | 298 | #endif |
9d13f5c4 | 299 | |
b13ae905 | 300 | #ifdef DTOR_LIST_BEGIN |
301 | DTOR_LIST_BEGIN; | |
302 | #else | |
9d13f5c4 | 303 | asm (DTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ |
b7c87ff2 | 304 | STATIC func_ptr __DTOR_LIST__[1] = { (func_ptr) (-1) }; |
b13ae905 | 305 | #endif |
9d13f5c4 | 306 | |
d757b8c9 | 307 | #ifdef EH_FRAME_SECTION_ASM_OP |
308 | /* Stick a label at the beginning of the frame unwind info so we can register | |
309 | and deregister it with the exception handling library code. */ | |
310 | ||
311 | asm (EH_FRAME_SECTION_ASM_OP); | |
312 | #ifdef INIT_SECTION_ASM_OP | |
313 | STATIC | |
314 | #endif | |
315 | char __EH_FRAME_BEGIN__[] = { }; | |
316 | #endif /* EH_FRAME_SECTION_ASM_OP */ | |
317 | ||
9d13f5c4 | 318 | #endif /* defined(CRT_BEGIN) */ |
319 | ||
320 | #ifdef CRT_END | |
321 | ||
322 | #ifdef INIT_SECTION_ASM_OP | |
323 | ||
b7c87ff2 | 324 | #ifdef OBJECT_FORMAT_ELF |
9d13f5c4 | 325 | |
b7c87ff2 | 326 | static func_ptr __CTOR_END__[]; |
327 | static void | |
328 | __do_global_ctors_aux () | |
329 | { | |
330 | func_ptr *p; | |
331 | for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--) | |
332 | (*p) (); | |
333 | } | |
334 | ||
335 | /* Stick a call to __do_global_ctors_aux into the .init section. */ | |
a92771b8 | 336 | |
b7c87ff2 | 337 | static void |
338 | init_dummy () | |
339 | { | |
340 | asm (INIT_SECTION_ASM_OP); | |
341 | __do_global_ctors_aux (); | |
342 | #ifdef FORCE_INIT_SECTION_ALIGN | |
343 | FORCE_INIT_SECTION_ALIGN; | |
344 | #endif | |
345 | asm (TEXT_SECTION_ASM_OP); | |
baf8c510 | 346 | |
ad87de1e | 347 | /* This is a kludge. The i386 GNU/Linux dynamic linker needs ___brk_addr, |
31dcf09a | 348 | __environ and atexit (). We have to make sure they are in the .dynsym |
349 | section. We accomplish it by making a dummy call here. This | |
a92771b8 | 350 | code is never reached. */ |
baf8c510 | 351 | |
31dcf09a | 352 | #if defined(__linux__) && defined(__PIC__) && defined(__i386__) |
baf8c510 | 353 | { |
354 | extern void *___brk_addr; | |
355 | extern char **__environ; | |
356 | ||
357 | ___brk_addr = __environ; | |
358 | atexit (); | |
359 | } | |
360 | #endif | |
b7c87ff2 | 361 | } |
362 | ||
363 | #else /* OBJECT_FORMAT_ELF */ | |
364 | ||
365 | /* Stick the real initialization code, followed by a normal sort of | |
366 | function epilogue at the very end of the .init section for this | |
367 | entire root executable file or for this entire shared library file. | |
368 | ||
369 | Note that we use some tricks here to get *just* the body and just | |
370 | a function epilogue (but no function prologue) into the .init | |
c3418f42 | 371 | section of the crtend.o file. Specifically, we switch to the .text |
b7c87ff2 | 372 | section, start to define a function, and then we switch to the .init |
373 | section just before the body code. | |
374 | ||
375 | Earlier on, we put the corresponding function prologue into the .init | |
376 | section of the crtbegin.o file (which will be linked in first). | |
377 | ||
378 | Note that we want to invoke all constructors for C++ file-scope static- | |
379 | storage objects AFTER any other possible initialization actions which | |
380 | may be performed by the code in the .init section contributions made by | |
381 | other libraries, etc. That's because those other initializations may | |
382 | include setup operations for very primitive things (e.g. initializing | |
383 | the state of the floating-point coprocessor, etc.) which should be done | |
a92771b8 | 384 | before we start to execute any of the user's code. */ |
9d13f5c4 | 385 | |
386 | static void | |
b13ae905 | 387 | __do_global_ctors_aux () /* prologue goes in .text section */ |
9d13f5c4 | 388 | { |
389 | asm (INIT_SECTION_ASM_OP); | |
390 | DO_GLOBAL_CTORS_BODY; | |
391 | ON_EXIT (__do_global_dtors, 0); | |
220345e0 | 392 | #ifdef FORCE_INIT_SECTION_ALIGN |
393 | FORCE_INIT_SECTION_ALIGN; | |
394 | #endif | |
9d13f5c4 | 395 | } /* epilogue and body go in .init section */ |
396 | ||
b7c87ff2 | 397 | #endif /* OBJECT_FORMAT_ELF */ |
398 | ||
8313a782 | 399 | #else /* defined(INIT_SECTION_ASM_OP) */ |
400 | ||
4e04a2df | 401 | #ifdef HAS_INIT_SECTION |
8313a782 | 402 | /* This case is used by the Irix 6 port, which supports named sections but |
403 | not an SVR4-style .init section. __do_global_ctors can be non-static | |
d757b8c9 | 404 | in this case because we protect it with -hidden_symbol. */ |
8313a782 | 405 | static func_ptr __CTOR_END__[]; |
406 | void | |
407 | __do_global_ctors () | |
408 | { | |
409 | func_ptr *p; | |
d757b8c9 | 410 | #ifdef EH_FRAME_SECTION_ASM_OP |
72ac783d | 411 | __frame_dummy (); |
d757b8c9 | 412 | #endif |
8313a782 | 413 | for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--) |
414 | (*p) (); | |
415 | } | |
4e04a2df | 416 | #endif |
8313a782 | 417 | |
9d13f5c4 | 418 | #endif /* defined(INIT_SECTION_ASM_OP) */ |
419 | ||
420 | /* Force cc1 to switch to .data section. */ | |
421 | static func_ptr force_to_data[0] = { }; | |
422 | ||
b7c87ff2 | 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. */ | |
428 | ||
b13ae905 | 429 | #ifdef CTOR_LIST_END |
430 | CTOR_LIST_END; | |
431 | #else | |
9d13f5c4 | 432 | asm (CTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ |
b7c87ff2 | 433 | STATIC func_ptr __CTOR_END__[1] = { (func_ptr) 0 }; |
b13ae905 | 434 | #endif |
9d13f5c4 | 435 | |
b13ae905 | 436 | #ifdef DTOR_LIST_END |
437 | DTOR_LIST_END; | |
438 | #else | |
9d13f5c4 | 439 | asm (DTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ |
b7c87ff2 | 440 | STATIC func_ptr __DTOR_END__[1] = { (func_ptr) 0 }; |
b13ae905 | 441 | #endif |
9d13f5c4 | 442 | |
d757b8c9 | 443 | #ifdef EH_FRAME_SECTION_ASM_OP |
444 | /* Terminate the frame unwind info section with a 4byte 0 as a sentinel; | |
445 | this would be the 'length' field in a real FDE. */ | |
446 | ||
447 | typedef unsigned int ui32 __attribute__ ((mode (SI))); | |
448 | asm (EH_FRAME_SECTION_ASM_OP); | |
449 | STATIC ui32 __FRAME_END__[] = { 0 }; | |
450 | #endif /* EH_FRAME_SECTION */ | |
451 | ||
9d13f5c4 | 452 | #endif /* defined(CRT_END) */ |