461 lines
15 KiB
C
461 lines
15 KiB
C
/* Specialized bits of code needed to support construction and
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destruction of file-scope objects in C++ code.
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Copyright (C) 1991, 94, 95, 96, 97, 1998 Free Software Foundation, Inc.
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Contributed by Ron Guilmette (rfg@monkeys.com).
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This file is part of GNU CC.
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GNU CC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU CC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU CC; see the file COPYING. If not, write to
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the Free Software Foundation, 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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/* As a special exception, if you link this library with files
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compiled with GCC to produce an executable, this does not cause
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the resulting executable to be covered by the GNU General Public License.
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This exception does not however invalidate any other reasons why
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the executable file might be covered by the GNU General Public License. */
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/* This file is a bit like libgcc1.c/libgcc2.c in that it is compiled
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multiple times and yields multiple .o files.
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This file is useful on target machines where the object file format
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supports multiple "user-defined" sections (e.g. COFF, ELF, ROSE). On
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such systems, this file allows us to avoid running collect (or any
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other such slow and painful kludge). Additionally, if the target
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system supports a .init section, this file allows us to support the
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linking of C++ code with a non-C++ main program.
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Note that if INIT_SECTION_ASM_OP is defined in the tm.h file, then
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this file *will* make use of the .init section. If that symbol is
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not defined however, then the .init section will not be used.
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Currently, only ELF and COFF are supported. It is likely however that
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ROSE could also be supported, if someone was willing to do the work to
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make whatever (small?) adaptations are needed. (Some work may be
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needed on the ROSE assembler and linker also.)
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This file must be compiled with gcc. */
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/* It is incorrect to include config.h here, because this file is being
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compiled for the target, and hence definitions concerning only the host
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do not apply. */
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#include "tm.h"
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#include "defaults.h"
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#include <stddef.h>
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#include "frame.h"
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/* Provide default definitions for the pseudo-ops used to switch to the
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.ctors and .dtors sections.
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Note that we want to give these sections the SHF_WRITE attribute
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because these sections will actually contain data (i.e. tables of
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addresses of functions in the current root executable or shared library
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file) and, in the case of a shared library, the relocatable addresses
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will have to be properly resolved/relocated (and then written into) by
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the dynamic linker when it actually attaches the given shared library
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to the executing process. (Note that on SVR4, you may wish to use the
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`-z text' option to the ELF linker, when building a shared library, as
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an additional check that you are doing everything right. But if you do
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use the `-z text' option when building a shared library, you will get
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errors unless the .ctors and .dtors sections are marked as writable
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via the SHF_WRITE attribute.) */
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#ifndef CTORS_SECTION_ASM_OP
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#define CTORS_SECTION_ASM_OP ".section\t.ctors,\"aw\""
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#endif
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#ifndef DTORS_SECTION_ASM_OP
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#define DTORS_SECTION_ASM_OP ".section\t.dtors,\"aw\""
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#endif
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#if !defined (EH_FRAME_SECTION_ASM_OP) && defined (DWARF2_UNWIND_INFO) && defined(ASM_OUTPUT_SECTION_NAME)
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#define EH_FRAME_SECTION_ASM_OP ".section\t.eh_frame,\"aw\""
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#endif
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#ifdef OBJECT_FORMAT_ELF
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/* Declare a pointer to void function type. */
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typedef void (*func_ptr) (void);
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#define STATIC static
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#else /* OBJECT_FORMAT_ELF */
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#include "gbl-ctors.h"
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#ifndef ON_EXIT
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#define ON_EXIT(a, b)
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#endif
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#define STATIC
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#endif /* OBJECT_FORMAT_ELF */
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#ifdef CRT_BEGIN
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#ifdef INIT_SECTION_ASM_OP
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#ifdef OBJECT_FORMAT_ELF
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/* Run all the global destructors on exit from the program. */
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/* Some systems place the number of pointers in the first word of the
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table. On SVR4 however, that word is -1. In all cases, the table is
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null-terminated. On SVR4, we start from the beginning of the list and
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invoke each per-compilation-unit destructor routine in order
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until we find that null.
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Note that this function MUST be static. There will be one of these
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functions in each root executable and one in each shared library, but
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although they all have the same code, each one is unique in that it
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refers to one particular associated `__DTOR_LIST__' which belongs to the
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same particular root executable or shared library file.
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On some systems, this routine is run more than once from the .fini,
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when exit is called recursively, so we arrange to remember where in
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the list we left off processing, and we resume at that point,
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should we be re-invoked. */
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static char __EH_FRAME_BEGIN__[];
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static func_ptr __DTOR_LIST__[];
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static void
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__do_global_dtors_aux ()
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{
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static func_ptr *p = __DTOR_LIST__ + 1;
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static int completed = 0;
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if (completed)
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return;
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while (*p)
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{
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p++;
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(*(p-1)) ();
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}
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#ifdef EH_FRAME_SECTION_ASM_OP
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__deregister_frame_info (__EH_FRAME_BEGIN__);
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#endif
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completed = 1;
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}
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/* Stick a call to __do_global_dtors_aux into the .fini section. */
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static void __attribute__ ((__unused__))
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fini_dummy ()
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{
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asm (FINI_SECTION_ASM_OP);
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__do_global_dtors_aux ();
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#ifdef FORCE_FINI_SECTION_ALIGN
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FORCE_FINI_SECTION_ALIGN;
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#endif
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asm (TEXT_SECTION_ASM_OP);
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}
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#ifdef EH_FRAME_SECTION_ASM_OP
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/* Stick a call to __register_frame_info into the .init section. For some
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reason calls with no arguments work more reliably in .init, so stick the
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call in another function. */
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static void
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frame_dummy ()
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{
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static struct object object;
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__register_frame_info (__EH_FRAME_BEGIN__, &object);
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}
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static void __attribute__ ((__unused__))
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init_dummy ()
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{
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asm (INIT_SECTION_ASM_OP);
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frame_dummy ();
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#ifdef FORCE_INIT_SECTION_ALIGN
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FORCE_INIT_SECTION_ALIGN;
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#endif
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asm (TEXT_SECTION_ASM_OP);
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}
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#endif /* EH_FRAME_SECTION_ASM_OP */
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#else /* OBJECT_FORMAT_ELF */
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/* The function __do_global_ctors_aux is compiled twice (once in crtbegin.o
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and once in crtend.o). It must be declared static to avoid a link
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error. Here, we define __do_global_ctors as an externally callable
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function. It is externally callable so that __main can invoke it when
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INVOKE__main is defined. This has the additional effect of forcing cc1
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to switch to the .text section. */
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static void __do_global_ctors_aux ();
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void __do_global_ctors ()
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{
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#ifdef INVOKE__main /* If __main won't actually call __do_global_ctors
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then it doesn't matter what's inside the function.
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The inside of __do_global_ctors_aux is called
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automatically in that case.
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And the Alliant fx2800 linker crashes
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on this reference. So prevent the crash. */
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__do_global_ctors_aux ();
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#endif
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}
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asm (INIT_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
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/* On some svr4 systems, the initial .init section preamble code provided in
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crti.o may do something, such as bump the stack, which we have to
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undo before we reach the function prologue code for __do_global_ctors
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(directly below). For such systems, define the macro INIT_SECTION_PREAMBLE
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to expand into the code needed to undo the actions of the crti.o file. */
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#ifdef INIT_SECTION_PREAMBLE
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INIT_SECTION_PREAMBLE;
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#endif
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/* A routine to invoke all of the global constructors upon entry to the
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program. We put this into the .init section (for systems that have
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such a thing) so that we can properly perform the construction of
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file-scope static-storage C++ objects within shared libraries. */
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static void
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__do_global_ctors_aux () /* prologue goes in .init section */
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{
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#ifdef FORCE_INIT_SECTION_ALIGN
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FORCE_INIT_SECTION_ALIGN; /* Explicit align before switch to .text */
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#endif
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asm (TEXT_SECTION_ASM_OP); /* don't put epilogue and body in .init */
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DO_GLOBAL_CTORS_BODY;
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ON_EXIT (__do_global_dtors, 0);
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}
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#endif /* OBJECT_FORMAT_ELF */
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#else /* defined(INIT_SECTION_ASM_OP) */
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#ifdef HAS_INIT_SECTION
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/* This case is used by the Irix 6 port, which supports named sections but
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not an SVR4-style .fini section. __do_global_dtors can be non-static
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in this case because we protect it with -hidden_symbol. */
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static char __EH_FRAME_BEGIN__[];
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static func_ptr __DTOR_LIST__[];
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void
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__do_global_dtors ()
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{
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func_ptr *p;
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for (p = __DTOR_LIST__ + 1; *p; p++)
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(*p) ();
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#ifdef EH_FRAME_SECTION_ASM_OP
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__deregister_frame_info (__EH_FRAME_BEGIN__);
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#endif
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}
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#ifdef EH_FRAME_SECTION_ASM_OP
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/* Define a function here to call __register_frame. crtend.o is linked in
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after libgcc.a, and hence can't call libgcc.a functions directly. That
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can lead to unresolved function references. */
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void
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__frame_dummy ()
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{
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static struct object object;
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__register_frame_info (__EH_FRAME_BEGIN__, &object);
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}
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#endif
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#endif
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#endif /* defined(INIT_SECTION_ASM_OP) */
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/* Force cc1 to switch to .data section. */
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static func_ptr force_to_data[0] __attribute__ ((__unused__)) = { };
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/* NOTE: In order to be able to support SVR4 shared libraries, we arrange
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to have one set of symbols { __CTOR_LIST__, __DTOR_LIST__, __CTOR_END__,
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__DTOR_END__ } per root executable and also one set of these symbols
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per shared library. So in any given whole process image, we may have
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multiple definitions of each of these symbols. In order to prevent
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these definitions from conflicting with one another, and in order to
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ensure that the proper lists are used for the initialization/finalization
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of each individual shared library (respectively), we give these symbols
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only internal (i.e. `static') linkage, and we also make it a point to
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refer to only the __CTOR_END__ symbol in crtend.o and the __DTOR_LIST__
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symbol in crtbegin.o, where they are defined. */
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/* The -1 is a flag to __do_global_[cd]tors
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indicating that this table does not start with a count of elements. */
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#ifdef CTOR_LIST_BEGIN
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CTOR_LIST_BEGIN;
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#else
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asm (CTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
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STATIC func_ptr __CTOR_LIST__[1] __attribute__ ((__unused__))
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= { (func_ptr) (-1) };
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#endif
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#ifdef DTOR_LIST_BEGIN
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DTOR_LIST_BEGIN;
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#else
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asm (DTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
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STATIC func_ptr __DTOR_LIST__[1] = { (func_ptr) (-1) };
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#endif
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#ifdef EH_FRAME_SECTION_ASM_OP
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/* Stick a label at the beginning of the frame unwind info so we can register
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and deregister it with the exception handling library code. */
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asm (EH_FRAME_SECTION_ASM_OP);
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#ifdef INIT_SECTION_ASM_OP
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STATIC
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#endif
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char __EH_FRAME_BEGIN__[] = { };
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#endif /* EH_FRAME_SECTION_ASM_OP */
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#endif /* defined(CRT_BEGIN) */
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#ifdef CRT_END
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#ifdef INIT_SECTION_ASM_OP
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#ifdef OBJECT_FORMAT_ELF
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static func_ptr __CTOR_END__[];
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static void
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__do_global_ctors_aux ()
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{
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func_ptr *p;
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for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
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(*p) ();
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}
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/* Stick a call to __do_global_ctors_aux into the .init section. */
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static void __attribute__ ((__unused__))
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init_dummy ()
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{
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asm (INIT_SECTION_ASM_OP);
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__do_global_ctors_aux ();
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#ifdef FORCE_INIT_SECTION_ALIGN
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FORCE_INIT_SECTION_ALIGN;
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#endif
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asm (TEXT_SECTION_ASM_OP);
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/* This is a kludge. The i386 GNU/Linux dynamic linker needs ___brk_addr,
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__environ and atexit (). We have to make sure they are in the .dynsym
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section. We accomplish it by making a dummy call here. This
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code is never reached. */
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#if defined(__linux__) && defined(__PIC__) && defined(__i386__)
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{
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extern void *___brk_addr;
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extern char **__environ;
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___brk_addr = __environ;
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atexit ();
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}
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#endif
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}
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#else /* OBJECT_FORMAT_ELF */
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/* Stick the real initialization code, followed by a normal sort of
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function epilogue at the very end of the .init section for this
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entire root executable file or for this entire shared library file.
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Note that we use some tricks here to get *just* the body and just
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a function epilogue (but no function prologue) into the .init
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section of the crtend.o file. Specifically, we switch to the .text
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section, start to define a function, and then we switch to the .init
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section just before the body code.
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Earlier on, we put the corresponding function prologue into the .init
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section of the crtbegin.o file (which will be linked in first).
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Note that we want to invoke all constructors for C++ file-scope static-
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storage objects AFTER any other possible initialization actions which
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may be performed by the code in the .init section contributions made by
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other libraries, etc. That's because those other initializations may
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include setup operations for very primitive things (e.g. initializing
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the state of the floating-point coprocessor, etc.) which should be done
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before we start to execute any of the user's code. */
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static void
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__do_global_ctors_aux () /* prologue goes in .text section */
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{
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asm (INIT_SECTION_ASM_OP);
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DO_GLOBAL_CTORS_BODY;
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ON_EXIT (__do_global_dtors, 0);
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} /* epilogue and body go in .init section */
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#ifdef FORCE_INIT_SECTION_ALIGN
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FORCE_INIT_SECTION_ALIGN;
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#endif
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asm (TEXT_SECTION_ASM_OP);
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#endif /* OBJECT_FORMAT_ELF */
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#else /* defined(INIT_SECTION_ASM_OP) */
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#ifdef HAS_INIT_SECTION
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/* This case is used by the Irix 6 port, which supports named sections but
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not an SVR4-style .init section. __do_global_ctors can be non-static
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in this case because we protect it with -hidden_symbol. */
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static func_ptr __CTOR_END__[];
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#ifdef EH_FRAME_SECTION_ASM_OP
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extern void __frame_dummy (void);
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#endif
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void
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__do_global_ctors ()
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{
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func_ptr *p;
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#ifdef EH_FRAME_SECTION_ASM_OP
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__frame_dummy ();
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#endif
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for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
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(*p) ();
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}
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#endif
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#endif /* defined(INIT_SECTION_ASM_OP) */
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/* Force cc1 to switch to .data section. */
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static func_ptr force_to_data[0] __attribute__ ((__unused__)) = { };
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/* Put a word containing zero at the end of each of our two lists of function
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addresses. Note that the words defined here go into the .ctors and .dtors
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sections of the crtend.o file, and since that file is always linked in
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last, these words naturally end up at the very ends of the two lists
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contained in these two sections. */
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#ifdef CTOR_LIST_END
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CTOR_LIST_END;
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#else
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asm (CTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
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STATIC func_ptr __CTOR_END__[1] = { (func_ptr) 0 };
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#endif
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#ifdef DTOR_LIST_END
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DTOR_LIST_END;
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#else
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asm (DTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
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STATIC func_ptr __DTOR_END__[1] __attribute__ ((__unused__))
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= { (func_ptr) 0 };
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#endif
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#ifdef EH_FRAME_SECTION_ASM_OP
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/* Terminate the frame unwind info section with a 4byte 0 as a sentinel;
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this would be the 'length' field in a real FDE. */
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typedef unsigned int ui32 __attribute__ ((mode (SI)));
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asm (EH_FRAME_SECTION_ASM_OP);
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STATIC ui32 __FRAME_END__[] __attribute__ ((__unused__)) = { 0 };
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#endif /* EH_FRAME_SECTION */
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#endif /* defined(CRT_END) */
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