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dc17e9e9 RS |
1 | /* Specialized bits of code needed to support construction and |
2 | destruction of file-scope objects in C++ code. | |
3 | ||
ed1817c6 | 4 | Written by Ron Guilmette (rfg@netcom.com) with help from Richard Stallman. |
dc17e9e9 | 5 | |
5378943d | 6 | Copyright (C) 1991, 1994, 1995 Free Software Foundation, Inc. |
dc17e9e9 RS |
7 | |
8 | This file is part of GNU CC. | |
9 | ||
10 | GNU CC is free software; you can redistribute it and/or modify | |
11 | it under the terms of the GNU General Public License as published by | |
12 | the Free Software Foundation; either version 2, or (at your option) | |
13 | any later version. | |
14 | ||
15 | GNU CC is distributed in the hope that it will be useful, | |
16 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | GNU General Public License for more details. | |
19 | ||
20 | You should have received a copy of the GNU General Public License | |
21 | along with GNU CC; see the file COPYING. If not, write to | |
22 | the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ | |
23 | ||
24 | /* As a special exception, if you link this library with files | |
25 | compiled with GCC to produce an executable, this does not cause | |
26 | the resulting executable to be covered by the GNU General Public License. | |
27 | This exception does not however invalidate any other reasons why | |
28 | the executable file might be covered by the GNU General Public License. */ | |
29 | ||
30 | /* This file is a bit like libgcc1.c/libgcc2.c in that it is compiled | |
31 | multiple times and yields multiple .o files. | |
32 | ||
33 | This file is useful on target machines where the object file format | |
34 | supports multiple "user-defined" sections (e.g. COFF, ELF, ROSE). On | |
35 | such systems, this file allows us to avoid running collect (or any | |
36 | other such slow and painful kludge). Additionally, if the target | |
37 | system supports a .init section, this file allows us to support the | |
38 | linking of C++ code with a non-C++ main program. | |
39 | ||
40 | Note that if INIT_SECTION_ASM_OP is defined in the tm.h file, then | |
41 | this file *will* make use of the .init section. If that symbol is | |
42 | not defined however, then the .init section will not be used. | |
43 | ||
37ce5b86 CH |
44 | Currently, only ELF and COFF are supported. It is likely however that |
45 | ROSE could also be supported, if someone was willing to do the work to | |
46 | make whatever (small?) adaptations are needed. (Some work may be | |
47 | needed on the ROSE assembler and linker also.) | |
dc17e9e9 RS |
48 | |
49 | This file must be compiled with gcc. */ | |
50 | ||
51 | /* It is incorrect to include config.h here, because this file is being | |
52 | compiled for the target, and hence definitions concerning only the host | |
53 | do not apply. */ | |
54 | ||
55 | #include "tm.h" | |
56 | ||
68d69835 JM |
57 | /* Provide default definitions for the pseudo-ops used to switch to the |
58 | .ctors and .dtors sections. | |
59 | ||
60 | Note that we want to give these sections the SHF_WRITE attribute | |
61 | because these sections will actually contain data (i.e. tables of | |
62 | addresses of functions in the current root executable or shared library | |
63 | file) and, in the case of a shared library, the relocatable addresses | |
64 | will have to be properly resolved/relocated (and then written into) by | |
65 | the dynamic linker when it actually attaches the given shared library | |
66 | to the executing process. (Note that on SVR4, you may wish to use the | |
67 | `-z text' option to the ELF linker, when building a shared library, as | |
68 | an additional check that you are doing everything right. But if you do | |
69 | use the `-z text' option when building a shared library, you will get | |
70 | errors unless the .ctors and .dtors sections are marked as writable | |
71 | via the SHF_WRITE attribute.) */ | |
72 | ||
dc17e9e9 | 73 | #ifndef CTORS_SECTION_ASM_OP |
68d69835 | 74 | #define CTORS_SECTION_ASM_OP ".section\t.ctors,\"aw\"" |
dc17e9e9 RS |
75 | #endif |
76 | #ifndef DTORS_SECTION_ASM_OP | |
68d69835 | 77 | #define DTORS_SECTION_ASM_OP ".section\t.dtors,\"aw\"" |
dc17e9e9 RS |
78 | #endif |
79 | ||
68d69835 JM |
80 | #ifdef OBJECT_FORMAT_ELF |
81 | ||
82 | /* Declare a pointer to void function type. */ | |
83 | typedef void (*func_ptr) (void); | |
84 | #define STATIC static | |
85 | ||
86 | #else /* OBJECT_FORMAT_ELF */ | |
87 | ||
dc17e9e9 RS |
88 | #include "gbl-ctors.h" |
89 | ||
90 | #ifndef ON_EXIT | |
91 | #define ON_EXIT(a, b) | |
92 | #endif | |
68d69835 JM |
93 | #define STATIC |
94 | ||
95 | #endif /* OBJECT_FORMAT_ELF */ | |
dc17e9e9 RS |
96 | |
97 | #ifdef CRT_BEGIN | |
98 | ||
99 | #ifdef INIT_SECTION_ASM_OP | |
100 | ||
68d69835 JM |
101 | #ifdef OBJECT_FORMAT_ELF |
102 | ||
103 | /* Run all the global destructors on exit from the program. */ | |
104 | ||
105 | /* Some systems place the number of pointers in the first word of the | |
106 | table. On SVR4 however, that word is -1. In all cases, the table is | |
107 | null-terminated. On SVR4, we start from the beginning of the list and | |
108 | invoke each per-compilation-unit destructor routine in order | |
109 | until we find that null. | |
110 | ||
111 | Note that this function MUST be static. There will be one of these | |
112 | functions in each root executable and one in each shared library, but | |
113 | although they all have the same code, each one is unique in that it | |
114 | refers to one particular associated `__DTOR_LIST__' which belongs to the | |
115 | same particular root executable or shared library file. */ | |
116 | ||
117 | static func_ptr __DTOR_LIST__[]; | |
118 | static void | |
119 | __do_global_dtors_aux () | |
120 | { | |
121 | func_ptr *p; | |
122 | for (p = __DTOR_LIST__ + 1; *p; p++) | |
123 | (*p) (); | |
124 | } | |
125 | ||
126 | /* Stick a call to __do_global_dtors_aux into the .fini section. */ | |
127 | static void | |
128 | fini_dummy () | |
129 | { | |
130 | asm (FINI_SECTION_ASM_OP); | |
131 | __do_global_dtors_aux (); | |
132 | #ifdef FORCE_FINI_SECTION_ALIGN | |
133 | FORCE_FINI_SECTION_ALIGN; | |
134 | #endif | |
135 | asm (TEXT_SECTION_ASM_OP); | |
136 | } | |
137 | ||
138 | #else /* OBJECT_FORMAT_ELF */ | |
139 | ||
b335c2cc | 140 | /* The function __do_global_ctors_aux is compiled twice (once in crtbegin.o |
b71a4aa9 | 141 | and once in crtend.o). It must be declared static to avoid a link |
b335c2cc TW |
142 | error. Here, we define __do_global_ctors as an externally callable |
143 | function. It is externally callable so that __main can invoke it when | |
144 | INVOKE__main is defined. This has the additional effect of forcing cc1 | |
145 | to switch to the .text section. */ | |
93c3d169 | 146 | static void __do_global_ctors_aux (); |
329d2160 RS |
147 | void __do_global_ctors () |
148 | { | |
149 | #ifdef INVOKE__main /* If __main won't actually call __do_global_ctors | |
150 | then it doesn't matter what's inside the function. | |
151 | The inside of __do_global_ctors_aux is called | |
152 | automatically in that case. | |
153 | And the Alliant fx2800 linker crashes | |
154 | on this reference. So prevent the crash. */ | |
155 | __do_global_ctors_aux (); | |
156 | #endif | |
157 | } | |
dc17e9e9 RS |
158 | |
159 | asm (INIT_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ | |
160 | ||
5378943d RK |
161 | /* On some svr4 systems, the initial .init section preamble code provided in |
162 | crti.o may do something, such as bump the stack, which we have to | |
163 | undo before we reach the function prologue code for __do_global_ctors | |
164 | (directly below). For such systems, define the macro INIT_SECTION_PREAMBLE | |
165 | to expand into the code needed to undo the actions of the crti.o file. */ | |
166 | ||
167 | #ifdef INIT_SECTION_PREAMBLE | |
168 | INIT_SECTION_PREAMBLE; | |
169 | #endif | |
170 | ||
dc17e9e9 RS |
171 | /* A routine to invoke all of the global constructors upon entry to the |
172 | program. We put this into the .init section (for systems that have | |
173 | such a thing) so that we can properly perform the construction of | |
174 | file-scope static-storage C++ objects within shared libraries. */ | |
175 | ||
176 | static void | |
b335c2cc | 177 | __do_global_ctors_aux () /* prologue goes in .init section */ |
dc17e9e9 | 178 | { |
5868ca20 JW |
179 | #ifdef FORCE_INIT_SECTION_ALIGN |
180 | FORCE_INIT_SECTION_ALIGN; /* Explicit align before switch to .text */ | |
181 | #endif | |
dc17e9e9 RS |
182 | asm (TEXT_SECTION_ASM_OP); /* don't put epilogue and body in .init */ |
183 | DO_GLOBAL_CTORS_BODY; | |
184 | ON_EXIT (__do_global_dtors, 0); | |
185 | } | |
186 | ||
68d69835 | 187 | #endif /* OBJECT_FORMAT_ELF */ |
dc17e9e9 RS |
188 | #endif /* defined(INIT_SECTION_ASM_OP) */ |
189 | ||
190 | /* Force cc1 to switch to .data section. */ | |
191 | static func_ptr force_to_data[0] = { }; | |
192 | ||
68d69835 JM |
193 | /* NOTE: In order to be able to support SVR4 shared libraries, we arrange |
194 | to have one set of symbols { __CTOR_LIST__, __DTOR_LIST__, __CTOR_END__, | |
195 | __DTOR_END__ } per root executable and also one set of these symbols | |
196 | per shared library. So in any given whole process image, we may have | |
197 | multiple definitions of each of these symbols. In order to prevent | |
198 | these definitions from conflicting with one another, and in order to | |
199 | ensure that the proper lists are used for the initialization/finalization | |
200 | of each individual shared library (respectively), we give these symbols | |
201 | only internal (i.e. `static') linkage, and we also make it a point to | |
202 | refer to only the __CTOR_END__ symbol in crtend.o and the __DTOR_LIST__ | |
203 | symbol in crtbegin.o, where they are defined. */ | |
204 | ||
dc17e9e9 RS |
205 | /* The -1 is a flag to __do_global_[cd]tors |
206 | indicating that this table does not start with a count of elements. */ | |
b335c2cc TW |
207 | #ifdef CTOR_LIST_BEGIN |
208 | CTOR_LIST_BEGIN; | |
209 | #else | |
dc17e9e9 | 210 | asm (CTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ |
68d69835 | 211 | STATIC func_ptr __CTOR_LIST__[1] = { (func_ptr) (-1) }; |
b335c2cc | 212 | #endif |
dc17e9e9 | 213 | |
b335c2cc TW |
214 | #ifdef DTOR_LIST_BEGIN |
215 | DTOR_LIST_BEGIN; | |
216 | #else | |
dc17e9e9 | 217 | asm (DTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ |
68d69835 | 218 | STATIC func_ptr __DTOR_LIST__[1] = { (func_ptr) (-1) }; |
b335c2cc | 219 | #endif |
dc17e9e9 RS |
220 | |
221 | #endif /* defined(CRT_BEGIN) */ | |
222 | ||
223 | #ifdef CRT_END | |
224 | ||
225 | #ifdef INIT_SECTION_ASM_OP | |
226 | ||
68d69835 | 227 | #ifdef OBJECT_FORMAT_ELF |
dc17e9e9 | 228 | |
68d69835 JM |
229 | static func_ptr __CTOR_END__[]; |
230 | static void | |
231 | __do_global_ctors_aux () | |
232 | { | |
233 | func_ptr *p; | |
234 | for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--) | |
235 | (*p) (); | |
236 | } | |
237 | ||
238 | /* Stick a call to __do_global_ctors_aux into the .init section. */ | |
239 | static void | |
240 | init_dummy () | |
241 | { | |
242 | asm (INIT_SECTION_ASM_OP); | |
243 | __do_global_ctors_aux (); | |
244 | #ifdef FORCE_INIT_SECTION_ALIGN | |
245 | FORCE_INIT_SECTION_ALIGN; | |
246 | #endif | |
247 | asm (TEXT_SECTION_ASM_OP); | |
bced43dd RK |
248 | |
249 | /* This is a kludge. The Linux dynamic linker needs ___brk_addr, __environ | |
250 | and atexit (). We have to make sure they are in the .dynsym section. We | |
251 | accomplish it by making a dummy call here. This | |
252 | code is never reached. */ | |
253 | ||
254 | #if defined(__linux__) && defined(__PIC__) | |
255 | { | |
256 | extern void *___brk_addr; | |
257 | extern char **__environ; | |
258 | ||
259 | ___brk_addr = __environ; | |
260 | atexit (); | |
261 | } | |
262 | #endif | |
68d69835 JM |
263 | } |
264 | ||
265 | #else /* OBJECT_FORMAT_ELF */ | |
266 | ||
267 | /* Stick the real initialization code, followed by a normal sort of | |
268 | function epilogue at the very end of the .init section for this | |
269 | entire root executable file or for this entire shared library file. | |
270 | ||
271 | Note that we use some tricks here to get *just* the body and just | |
272 | a function epilogue (but no function prologue) into the .init | |
9faa82d8 | 273 | section of the crtend.o file. Specifically, we switch to the .text |
68d69835 JM |
274 | section, start to define a function, and then we switch to the .init |
275 | section just before the body code. | |
276 | ||
277 | Earlier on, we put the corresponding function prologue into the .init | |
278 | section of the crtbegin.o file (which will be linked in first). | |
279 | ||
280 | Note that we want to invoke all constructors for C++ file-scope static- | |
281 | storage objects AFTER any other possible initialization actions which | |
282 | may be performed by the code in the .init section contributions made by | |
283 | other libraries, etc. That's because those other initializations may | |
284 | include setup operations for very primitive things (e.g. initializing | |
285 | the state of the floating-point coprocessor, etc.) which should be done | |
286 | before we start to execute any of the user's code. */ | |
dc17e9e9 RS |
287 | |
288 | static void | |
b335c2cc | 289 | __do_global_ctors_aux () /* prologue goes in .text section */ |
dc17e9e9 RS |
290 | { |
291 | asm (INIT_SECTION_ASM_OP); | |
292 | DO_GLOBAL_CTORS_BODY; | |
293 | ON_EXIT (__do_global_dtors, 0); | |
294 | } /* epilogue and body go in .init section */ | |
295 | ||
68d69835 JM |
296 | #endif /* OBJECT_FORMAT_ELF */ |
297 | ||
dc17e9e9 RS |
298 | #endif /* defined(INIT_SECTION_ASM_OP) */ |
299 | ||
300 | /* Force cc1 to switch to .data section. */ | |
301 | static func_ptr force_to_data[0] = { }; | |
302 | ||
68d69835 JM |
303 | /* Put a word containing zero at the end of each of our two lists of function |
304 | addresses. Note that the words defined here go into the .ctors and .dtors | |
305 | sections of the crtend.o file, and since that file is always linked in | |
306 | last, these words naturally end up at the very ends of the two lists | |
307 | contained in these two sections. */ | |
308 | ||
b335c2cc TW |
309 | #ifdef CTOR_LIST_END |
310 | CTOR_LIST_END; | |
311 | #else | |
dc17e9e9 | 312 | asm (CTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ |
68d69835 | 313 | STATIC func_ptr __CTOR_END__[1] = { (func_ptr) 0 }; |
b335c2cc | 314 | #endif |
dc17e9e9 | 315 | |
b335c2cc TW |
316 | #ifdef DTOR_LIST_END |
317 | DTOR_LIST_END; | |
318 | #else | |
dc17e9e9 | 319 | asm (DTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ |
68d69835 | 320 | STATIC func_ptr __DTOR_END__[1] = { (func_ptr) 0 }; |
b335c2cc | 321 | #endif |
dc17e9e9 RS |
322 | |
323 | #endif /* defined(CRT_END) */ |