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56f0a28b C |
1 | /* Specialized bits of code needed to support construction and |
2 | destruction of file-scope objects in C++ code. | |
3 | ||
4 | Written by Ron Guilmette (rfg@ncd.com) with help from Richard Stallman. | |
5 | ||
6 | Copyright (C) 1991 Free Software Foundation, Inc. | |
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 | ||
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.) | |
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 | ||
57 | #ifndef CTORS_SECTION_ASM_OP | |
58 | #define CTORS_SECTION_ASM_OP ".section\t.ctors,\"a\",@progbits" | |
59 | #endif | |
60 | #ifndef DTORS_SECTION_ASM_OP | |
61 | #define DTORS_SECTION_ASM_OP ".section\t.dtors,\"a\",@progbits" | |
62 | #endif | |
63 | ||
64 | #include "gbl-ctors.h" | |
65 | ||
66 | #ifndef ON_EXIT | |
67 | #define ON_EXIT(a, b) | |
68 | #endif | |
69 | ||
70 | #ifdef CRT_BEGIN | |
71 | ||
72 | #ifdef INIT_SECTION_ASM_OP | |
73 | ||
74 | /* The function __do_global_ctors_aux is compiled twice (once in crtbegin.o | |
75 | and once in crtend.o). It must be declared static to avoid a link | |
76 | error. Here, we define __do_global_ctors as an externally callable | |
77 | function. It is externally callable so that __main can invoke it when | |
78 | INVOKE__main is defined. This has the additional effect of forcing cc1 | |
79 | to switch to the .text section. */ | |
80 | static void __do_global_ctors_aux (); | |
81 | void __do_global_ctors () | |
82 | { | |
83 | #ifdef INVOKE__main /* If __main won't actually call __do_global_ctors | |
84 | then it doesn't matter what's inside the function. | |
85 | The inside of __do_global_ctors_aux is called | |
86 | automatically in that case. | |
87 | And the Alliant fx2800 linker crashes | |
88 | on this reference. So prevent the crash. */ | |
89 | __do_global_ctors_aux (); | |
90 | #endif | |
91 | } | |
92 | ||
93 | asm (INIT_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ | |
94 | ||
95 | /* On some svr4 systems, the .init section preamble code provided in | |
96 | crti.o may do some evil things which we have to undo before we reach | |
97 | the function prologue code for __do_global_ctors (directly below). | |
98 | For such systems, define the macro INIT_SECTION_PREAMBLE to | |
99 | expand into the code needed to undo the actions of the crti.o file. */ | |
100 | ||
101 | #ifdef INIT_SECTION_PREAMBLE | |
102 | INIT_SECTION_PREAMBLE; | |
103 | #endif | |
104 | ||
105 | /* A routine to invoke all of the global constructors upon entry to the | |
106 | program. We put this into the .init section (for systems that have | |
107 | such a thing) so that we can properly perform the construction of | |
108 | file-scope static-storage C++ objects within shared libraries. */ | |
109 | ||
110 | static void | |
111 | __do_global_ctors_aux () /* prologue goes in .init section */ | |
112 | { | |
113 | asm (TEXT_SECTION_ASM_OP); /* don't put epilogue and body in .init */ | |
114 | DO_GLOBAL_CTORS_BODY; | |
115 | ON_EXIT (__do_global_dtors, 0); | |
116 | } | |
117 | ||
118 | #endif /* defined(INIT_SECTION_ASM_OP) */ | |
119 | ||
120 | /* Force cc1 to switch to .data section. */ | |
121 | static func_ptr force_to_data[0] = { }; | |
122 | ||
123 | /* The -1 is a flag to __do_global_[cd]tors | |
124 | indicating that this table does not start with a count of elements. */ | |
125 | #ifdef CTOR_LIST_BEGIN | |
126 | CTOR_LIST_BEGIN; | |
127 | #else | |
128 | asm (CTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ | |
129 | func_ptr __CTOR_LIST__[1] = { (func_ptr) (-1) }; | |
130 | #endif | |
131 | ||
132 | #ifdef DTOR_LIST_BEGIN | |
133 | DTOR_LIST_BEGIN; | |
134 | #else | |
135 | asm (DTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ | |
136 | func_ptr __DTOR_LIST__[1] = { (func_ptr) (-1) }; | |
137 | #endif | |
138 | ||
139 | #endif /* defined(CRT_BEGIN) */ | |
140 | ||
141 | #ifdef CRT_END | |
142 | ||
143 | #ifdef INIT_SECTION_ASM_OP | |
144 | ||
145 | /* A routine to invoke all of the global constructors upon entry to the | |
146 | program. We put this into the .init section (for systems that have | |
147 | such a thing) so that we can properly perform the construction of | |
148 | file-scope static-storage C++ objects within shared libraries. | |
149 | ||
150 | This must be virtually identical to the one above so that we can | |
151 | insure that the function prologue from the one above works correctly | |
152 | with the epilogue from this one. (They will both go into the .init | |
153 | section as the first and last things (respectively) that the linker | |
154 | will put in that section.) | |
155 | */ | |
156 | ||
157 | static void | |
158 | __do_global_ctors_aux () /* prologue goes in .text section */ | |
159 | { | |
160 | asm (INIT_SECTION_ASM_OP); | |
161 | DO_GLOBAL_CTORS_BODY; | |
162 | ON_EXIT (__do_global_dtors, 0); | |
163 | } /* epilogue and body go in .init section */ | |
164 | ||
165 | #endif /* defined(INIT_SECTION_ASM_OP) */ | |
166 | ||
167 | /* Force cc1 to switch to .data section. */ | |
168 | static func_ptr force_to_data[0] = { }; | |
169 | ||
170 | #ifdef CTOR_LIST_END | |
171 | CTOR_LIST_END; | |
172 | #else | |
173 | asm (CTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ | |
174 | func_ptr __CTOR_END__[1] = { (func_ptr) 0 }; | |
175 | #endif | |
176 | ||
177 | #ifdef DTOR_LIST_END | |
178 | DTOR_LIST_END; | |
179 | #else | |
180 | asm (DTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ | |
181 | func_ptr __DTOR_END__[1] = { (func_ptr) 0 }; | |
182 | #endif | |
183 | ||
184 | #endif /* defined(CRT_END) */ |