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 is actually supported.
45 The other formats probably need just alternative macro definitions.
47 This file must be compiled with gcc. */
49 /* It is incorrect to include config.h here, because this file is being
50 compiled for the target, and hence definitions concerning only the host
55 #ifndef CTORS_SECTION_ASM_OP
56 #define CTORS_SECTION_ASM_OP "\t.section\t.ctors,\"a\",@progbits"
58 #ifndef DTORS_SECTION_ASM_OP
59 #define DTORS_SECTION_ASM_OP "\t.section\t.dtors,\"a\",@progbits"
62 #include "gbl-ctors.h"
70 #ifdef INIT_SECTION_ASM_OP
72 /* Force cc1 to switch to .text section. */
73 static void force_to_text () { }
75 asm (INIT_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
77 /* On some svr4 systems, the .init section preamble code provided in
78 crti.o may do some evil things which we have to undo before we reach
79 the function prologue code for __do_global_ctors (directly below).
80 For such systems, define the macro INIT_SECTION_PREAMBLE to
81 expand into the code needed to undo the actions of the crti.o file. */
83 #ifdef INIT_SECTION_PREAMBLE
84 INIT_SECTION_PREAMBLE;
87 /* A routine to invoke all of the global constructors upon entry to the
88 program. We put this into the .init section (for systems that have
89 such a thing) so that we can properly perform the construction of
90 file-scope static-storage C++ objects within shared libraries. */
93 __do_global_ctors () /* prologue goes in .init section */
95 asm (TEXT_SECTION_ASM_OP); /* don't put epilogue and body in .init */
97 ON_EXIT (__do_global_dtors, 0);
100 #endif /* defined(INIT_SECTION_ASM_OP) */
102 /* Force cc1 to switch to .data section. */
103 static func_ptr force_to_data[0] = { };
105 /* The -1 is a flag to __do_global_[cd]tors
106 indicating that this table does not start with a count of elements. */
107 asm (CTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
108 func_ptr __CTOR_LIST__[1] = { (func_ptr) (-1) };
110 asm (DTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
111 func_ptr __DTOR_LIST__[1] = { (func_ptr) (-1) };
113 #endif /* defined(CRT_BEGIN) */
117 #ifdef INIT_SECTION_ASM_OP
119 /* A routine to invoke all of the global constructors upon entry to the
120 program. We put this into the .init section (for systems that have
121 such a thing) so that we can properly perform the construction of
122 file-scope static-storage C++ objects within shared libraries.
124 This must be virtually identical to the one above so that we can
125 insure that the function prologue from the one above works correctly
126 with the epilogue from this one. (They will both go into the .init
127 section as the first and last things (respectively) that the linker
128 will put in that section.)
132 __do_global_ctors () /* prologue goes in .text section */
134 asm (INIT_SECTION_ASM_OP);
135 DO_GLOBAL_CTORS_BODY;
136 ON_EXIT (__do_global_dtors, 0);
137 } /* epilogue and body go in .init section */
139 #endif /* defined(INIT_SECTION_ASM_OP) */
141 /* Force cc1 to switch to .data section. */
142 static func_ptr force_to_data[0] = { };
144 asm (CTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
145 func_ptr __CTOR_END__[1] = { (func_ptr) 0 };
147 asm (DTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
148 func_ptr __DTOR_END__[1] = { (func_ptr) 0 };
150 #endif /* defined(CRT_END) */