1 /* Specialized bits of code needed to support construction and
2 destruction of file-scope objects in C++ code.
4 Written by Ron Guilmette (rfg@ncd.com) with help from Richard Stallman.
6 Copyright (C) 1991 Free Software Foundation, Inc.
8 This file is part of GNU CC.
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)
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.
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. */
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. */
30 /* This file is a bit like libgcc1.c/libgcc2.c in that it is compiled
31 multiple times and yields multiple .o files.
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.
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.
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.)
49 This file must be compiled with gcc. */
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
57 #ifndef CTORS_SECTION_ASM_OP
58 #define CTORS_SECTION_ASM_OP ".section\t.ctors,\"a\",@progbits"
60 #ifndef DTORS_SECTION_ASM_OP
61 #define DTORS_SECTION_ASM_OP ".section\t.dtors,\"a\",@progbits"
64 #include "gbl-ctors.h"
72 #ifdef INIT_SECTION_ASM_OP
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 ()
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 ();
93 asm (INIT_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
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. */
101 #ifdef INIT_SECTION_PREAMBLE
102 INIT_SECTION_PREAMBLE;
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. */
111 __do_global_ctors_aux () /* prologue goes in .init section */
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);
118 #endif /* defined(INIT_SECTION_ASM_OP) */
120 /* Force cc1 to switch to .data section. */
121 static func_ptr force_to_data[0] = { };
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
128 asm (CTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
129 func_ptr __CTOR_LIST__[1] = { (func_ptr) (-1) };
132 #ifdef DTOR_LIST_BEGIN
135 asm (DTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
136 func_ptr __DTOR_LIST__[1] = { (func_ptr) (-1) };
139 #endif /* defined(CRT_BEGIN) */
143 #ifdef INIT_SECTION_ASM_OP
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.
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.)
158 __do_global_ctors_aux () /* prologue goes in .text section */
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 */
165 #endif /* defined(INIT_SECTION_ASM_OP) */
167 /* Force cc1 to switch to .data section. */
168 static func_ptr force_to_data[0] = { };
173 asm (CTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
174 func_ptr __CTOR_END__[1] = { (func_ptr) 0 };
180 asm (DTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
181 func_ptr __DTOR_END__[1] = { (func_ptr) 0 };
184 #endif /* defined(CRT_END) */