/* Specialized bits of code needed to support construction and
destruction of file-scope objects in C++ code.
-
- Written by Ron Guilmette (rfg@ncd.com) with help from Richard Stallman.
-
-Copyright (C) 1991 Free Software Foundation, Inc.
+ Copyright (C) 1991, 1994, 1995, 1996, 1997, 1998,
+ 1999, 2000 Free Software Foundation, Inc.
+ Contributed by Ron Guilmette (rfg@monkeys.com).
This file is part of GNU CC.
You should have received a copy of the GNU General Public License
along with GNU CC; see the file COPYING. If not, write to
-the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
+the Free Software Foundation, 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA. */
/* As a special exception, if you link this library with files
compiled with GCC to produce an executable, this does not cause
compiled for the target, and hence definitions concerning only the host
do not apply. */
+#include "auto-host.h"
#include "tm.h"
+#include "tsystem.h"
+
+#include "defaults.h"
+#include "frame.h"
+
+/* We do not want to add the weak attribute to the declarations of these
+ routines in frame.h because that will cause the definition of these
+ symbols to be weak as well.
+
+ This exposes a core issue, how to handle creating weak references vs
+ how to create weak definitions. Either we have to have the definition
+ of TARGET_WEAK_ATTRIBUTE be conditional in the shared header files or
+ have a second declaration if we want a function's references to be weak,
+ but not its definition.
+
+ Making TARGET_WEAK_ATTRIBUTE conditional seems like a good solution until
+ one thinks about scaling to larger problems -- ie, the condition under
+ which TARGET_WEAK_ATTRIBUTE is active will eventually get far too
+ complicated.
+
+ So, we take an approach similar to #pragma weak -- we have a second
+ declaration for functions that we want to have weak references.
+
+ Neither way is particularly good. */
+
+/* References to __register_frame_info and __deregister_frame_info should
+ be weak in this file if at all possible. */
+extern void __register_frame_info (void *, struct object *)
+ TARGET_ATTRIBUTE_WEAK;
+
+extern void *__deregister_frame_info (void *)
+ TARGET_ATTRIBUTE_WEAK;
+
+#ifndef OBJECT_FORMAT_MACHO
+
+/* Provide default definitions for the pseudo-ops used to switch to the
+ .ctors and .dtors sections.
+
+ Note that we want to give these sections the SHF_WRITE attribute
+ because these sections will actually contain data (i.e. tables of
+ addresses of functions in the current root executable or shared library
+ file) and, in the case of a shared library, the relocatable addresses
+ will have to be properly resolved/relocated (and then written into) by
+ the dynamic linker when it actually attaches the given shared library
+ to the executing process. (Note that on SVR4, you may wish to use the
+ `-z text' option to the ELF linker, when building a shared library, as
+ an additional check that you are doing everything right. But if you do
+ use the `-z text' option when building a shared library, you will get
+ errors unless the .ctors and .dtors sections are marked as writable
+ via the SHF_WRITE attribute.) */
#ifndef CTORS_SECTION_ASM_OP
-#define CTORS_SECTION_ASM_OP ".section\t.ctors,\"a\",@progbits"
+#define CTORS_SECTION_ASM_OP ".section\t.ctors,\"aw\""
#endif
#ifndef DTORS_SECTION_ASM_OP
-#define DTORS_SECTION_ASM_OP ".section\t.dtors,\"a\",@progbits"
+#define DTORS_SECTION_ASM_OP ".section\t.dtors,\"aw\""
#endif
+#ifdef OBJECT_FORMAT_ELF
+
+/* Declare a pointer to void function type. */
+typedef void (*func_ptr) (void);
+#define STATIC static
+
+#else /* OBJECT_FORMAT_ELF */
+
#include "gbl-ctors.h"
-#ifndef ON_EXIT
-#define ON_EXIT(a, b)
-#endif
+#define STATIC
+
+#endif /* OBJECT_FORMAT_ELF */
#ifdef CRT_BEGIN
#ifdef INIT_SECTION_ASM_OP
+#ifdef OBJECT_FORMAT_ELF
+
+/* Declare the __dso_handle variable. It should have a unique value
+ in every shared-object; in a main program its value is zero. The
+ object should in any case be protected. This means the instance
+ in one DSO or the main program is not used in another object. The
+ dynamic linker takes care of this. */
+
+/* XXX Ideally the following should be implemented using
+ __attribute__ ((__visibility__ ("hidden")))
+ but the __attribute__ support is not yet there. */
+#ifdef HAVE_GAS_HIDDEN
+asm (".hidden\t__dso_handle");
+#endif
+
+#ifdef CRTSTUFFS_O
+void *__dso_handle = &__dso_handle;
+#else
+void *__dso_handle = 0;
+#endif
+
+/* The __cxa_finalize function may not be available so we use only a
+ weak declaration. */
+extern void __cxa_finalize (void *) TARGET_ATTRIBUTE_WEAK;
+
+/* Run all the global destructors on exit from the program. */
+
+/* Some systems place the number of pointers in the first word of the
+ table. On SVR4 however, that word is -1. In all cases, the table is
+ null-terminated. On SVR4, we start from the beginning of the list and
+ invoke each per-compilation-unit destructor routine in order
+ until we find that null.
+
+ Note that this function MUST be static. There will be one of these
+ functions in each root executable and one in each shared library, but
+ although they all have the same code, each one is unique in that it
+ refers to one particular associated `__DTOR_LIST__' which belongs to the
+ same particular root executable or shared library file.
+
+ On some systems, this routine is run more than once from the .fini,
+ when exit is called recursively, so we arrange to remember where in
+ the list we left off processing, and we resume at that point,
+ should we be re-invoked. */
+
+static char __EH_FRAME_BEGIN__[];
+static func_ptr __DTOR_LIST__[];
+static void
+__do_global_dtors_aux (void)
+{
+ static func_ptr *p = __DTOR_LIST__ + 1;
+ static int completed = 0;
+
+ if (completed)
+ return;
+
+#ifdef CRTSTUFFS_O
+ if (__cxa_finalize)
+ __cxa_finalize (__dso_handle);
+#endif
+
+ while (*p)
+ {
+ p++;
+ (*(p-1)) ();
+ }
+
+#ifdef EH_FRAME_SECTION_ASM_OP
+ if (__deregister_frame_info)
+ __deregister_frame_info (__EH_FRAME_BEGIN__);
+#endif
+ completed = 1;
+}
+
+
+/* Stick a call to __do_global_dtors_aux into the .fini section. */
+
+static void __attribute__ ((__unused__))
+fini_dummy (void)
+{
+ asm (FINI_SECTION_ASM_OP);
+ __do_global_dtors_aux ();
+#ifdef FORCE_FINI_SECTION_ALIGN
+ FORCE_FINI_SECTION_ALIGN;
+#endif
+ asm (TEXT_SECTION_ASM_OP);
+}
+
+#ifdef EH_FRAME_SECTION_ASM_OP
+/* Stick a call to __register_frame_info into the .init section. For some
+ reason calls with no arguments work more reliably in .init, so stick the
+ call in another function. */
+
+static void
+frame_dummy (void)
+{
+ static struct object object;
+ if (__register_frame_info)
+ __register_frame_info (__EH_FRAME_BEGIN__, &object);
+}
+
+static void __attribute__ ((__unused__))
+init_dummy (void)
+{
+ asm (INIT_SECTION_ASM_OP);
+ frame_dummy ();
+#ifdef FORCE_INIT_SECTION_ALIGN
+ FORCE_INIT_SECTION_ALIGN;
+#endif
+ asm (TEXT_SECTION_ASM_OP);
+}
+#endif /* EH_FRAME_SECTION_ASM_OP */
+
+#else /* OBJECT_FORMAT_ELF */
+
/* The function __do_global_ctors_aux is compiled twice (once in crtbegin.o
and once in crtend.o). It must be declared static to avoid a link
error. Here, we define __do_global_ctors as an externally callable
function. It is externally callable so that __main can invoke it when
INVOKE__main is defined. This has the additional effect of forcing cc1
to switch to the .text section. */
-static void __do_global_ctors_aux ();
-void __do_global_ctors ()
+
+static void __do_global_ctors_aux (void);
+void
+__do_global_ctors (void)
{
#ifdef INVOKE__main /* If __main won't actually call __do_global_ctors
then it doesn't matter what's inside the function.
asm (INIT_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
-/* On some svr4 systems, the .init section preamble code provided in
- crti.o may do some evil things which we have to undo before we reach
- the function prologue code for __do_global_ctors (directly below).
- For such systems, define the macro INIT_SECTION_PREAMBLE to
- expand into the code needed to undo the actions of the crti.o file. */
-
+/* On some svr4 systems, the initial .init section preamble code provided in
+ crti.o may do something, such as bump the stack, which we have to
+ undo before we reach the function prologue code for __do_global_ctors
+ (directly below). For such systems, define the macro INIT_SECTION_PREAMBLE
+ to expand into the code needed to undo the actions of the crti.o file. */
+
#ifdef INIT_SECTION_PREAMBLE
INIT_SECTION_PREAMBLE;
#endif
file-scope static-storage C++ objects within shared libraries. */
static void
-__do_global_ctors_aux () /* prologue goes in .init section */
+__do_global_ctors_aux (void) /* prologue goes in .init section */
{
#ifdef FORCE_INIT_SECTION_ALIGN
FORCE_INIT_SECTION_ALIGN; /* Explicit align before switch to .text */
#endif
asm (TEXT_SECTION_ASM_OP); /* don't put epilogue and body in .init */
DO_GLOBAL_CTORS_BODY;
- ON_EXIT (__do_global_dtors, 0);
+ atexit (__do_global_dtors);
+}
+
+#endif /* OBJECT_FORMAT_ELF */
+
+#else /* defined(INIT_SECTION_ASM_OP) */
+
+#ifdef HAS_INIT_SECTION
+/* This case is used by the Irix 6 port, which supports named sections but
+ not an SVR4-style .fini section. __do_global_dtors can be non-static
+ in this case because we protect it with -hidden_symbol. */
+
+static char __EH_FRAME_BEGIN__[];
+static func_ptr __DTOR_LIST__[];
+void
+__do_global_dtors (void)
+{
+ func_ptr *p;
+ for (p = __DTOR_LIST__ + 1; *p; p++)
+ (*p) ();
+
+#ifdef EH_FRAME_SECTION_ASM_OP
+ if (__deregister_frame_info)
+ __deregister_frame_info (__EH_FRAME_BEGIN__);
+#endif
+}
+
+#ifdef EH_FRAME_SECTION_ASM_OP
+/* Define a function here to call __register_frame. crtend.o is linked in
+ after libgcc.a, and hence can't call libgcc.a functions directly. That
+ can lead to unresolved function references. */
+void
+__frame_dummy (void)
+{
+ static struct object object;
+ if (__register_frame_info)
+ __register_frame_info (__EH_FRAME_BEGIN__, &object);
}
+#endif
+#endif
#endif /* defined(INIT_SECTION_ASM_OP) */
/* Force cc1 to switch to .data section. */
-static func_ptr force_to_data[0] = { };
+static func_ptr force_to_data[0] __attribute__ ((__unused__)) = { };
+
+/* NOTE: In order to be able to support SVR4 shared libraries, we arrange
+ to have one set of symbols { __CTOR_LIST__, __DTOR_LIST__, __CTOR_END__,
+ __DTOR_END__ } per root executable and also one set of these symbols
+ per shared library. So in any given whole process image, we may have
+ multiple definitions of each of these symbols. In order to prevent
+ these definitions from conflicting with one another, and in order to
+ ensure that the proper lists are used for the initialization/finalization
+ of each individual shared library (respectively), we give these symbols
+ only internal (i.e. `static') linkage, and we also make it a point to
+ refer to only the __CTOR_END__ symbol in crtend.o and the __DTOR_LIST__
+ symbol in crtbegin.o, where they are defined. */
/* The -1 is a flag to __do_global_[cd]tors
indicating that this table does not start with a count of elements. */
CTOR_LIST_BEGIN;
#else
asm (CTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
-func_ptr __CTOR_LIST__[1] = { (func_ptr) (-1) };
+STATIC func_ptr __CTOR_LIST__[1] __attribute__ ((__unused__))
+ = { (func_ptr) (-1) };
#endif
#ifdef DTOR_LIST_BEGIN
DTOR_LIST_BEGIN;
#else
asm (DTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
-func_ptr __DTOR_LIST__[1] = { (func_ptr) (-1) };
+STATIC func_ptr __DTOR_LIST__[1] = { (func_ptr) (-1) };
#endif
+#ifdef EH_FRAME_SECTION_ASM_OP
+/* Stick a label at the beginning of the frame unwind info so we can register
+ and deregister it with the exception handling library code. */
+
+asm (EH_FRAME_SECTION_ASM_OP);
+#ifdef INIT_SECTION_ASM_OP
+STATIC
+#endif
+char __EH_FRAME_BEGIN__[] = { };
+#endif /* EH_FRAME_SECTION_ASM_OP */
+
#endif /* defined(CRT_BEGIN) */
#ifdef CRT_END
#ifdef INIT_SECTION_ASM_OP
-/* A routine to invoke all of the global constructors upon entry to the
- program. We put this into the .init section (for systems that have
- such a thing) so that we can properly perform the construction of
- file-scope static-storage C++ objects within shared libraries.
+#ifdef OBJECT_FORMAT_ELF
+
+static func_ptr __CTOR_END__[];
+static void
+__do_global_ctors_aux (void)
+{
+ func_ptr *p;
+ for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
+ (*p) ();
+}
- This must be virtually identical to the one above so that we can
- insure that the function prologue from the one above works correctly
- with the epilogue from this one. (They will both go into the .init
- section as the first and last things (respectively) that the linker
- will put in that section.)
-*/
+/* Stick a call to __do_global_ctors_aux into the .init section. */
+
+static void __attribute__ ((__unused__))
+init_dummy (void)
+{
+ asm (INIT_SECTION_ASM_OP);
+ __do_global_ctors_aux ();
+#ifdef FORCE_INIT_SECTION_ALIGN
+ FORCE_INIT_SECTION_ALIGN;
+#endif
+ asm (TEXT_SECTION_ASM_OP);
+
+/* This is a kludge. The i386 GNU/Linux dynamic linker needs ___brk_addr,
+ __environ and atexit (). We have to make sure they are in the .dynsym
+ section. We accomplish it by making a dummy call here. This
+ code is never reached. */
+
+#if defined(__linux__) && defined(__PIC__) && defined(__i386__)
+ {
+ extern void *___brk_addr;
+ extern char **__environ;
+
+ ___brk_addr = __environ;
+ atexit (0);
+ }
+#endif
+}
+
+#else /* OBJECT_FORMAT_ELF */
+
+/* Stick the real initialization code, followed by a normal sort of
+ function epilogue at the very end of the .init section for this
+ entire root executable file or for this entire shared library file.
+
+ Note that we use some tricks here to get *just* the body and just
+ a function epilogue (but no function prologue) into the .init
+ section of the crtend.o file. Specifically, we switch to the .text
+ section, start to define a function, and then we switch to the .init
+ section just before the body code.
+
+ Earlier on, we put the corresponding function prologue into the .init
+ section of the crtbegin.o file (which will be linked in first).
+
+ Note that we want to invoke all constructors for C++ file-scope static-
+ storage objects AFTER any other possible initialization actions which
+ may be performed by the code in the .init section contributions made by
+ other libraries, etc. That's because those other initializations may
+ include setup operations for very primitive things (e.g. initializing
+ the state of the floating-point coprocessor, etc.) which should be done
+ before we start to execute any of the user's code. */
static void
-__do_global_ctors_aux () /* prologue goes in .text section */
+__do_global_ctors_aux (void) /* prologue goes in .text section */
{
asm (INIT_SECTION_ASM_OP);
DO_GLOBAL_CTORS_BODY;
- ON_EXIT (__do_global_dtors, 0);
+ atexit (__do_global_dtors);
} /* epilogue and body go in .init section */
+#ifdef FORCE_INIT_SECTION_ALIGN
+FORCE_INIT_SECTION_ALIGN;
+#endif
+
+asm (TEXT_SECTION_ASM_OP);
+
+#endif /* OBJECT_FORMAT_ELF */
+
+#else /* defined(INIT_SECTION_ASM_OP) */
+
+#ifdef HAS_INIT_SECTION
+/* This case is used by the Irix 6 port, which supports named sections but
+ not an SVR4-style .init section. __do_global_ctors can be non-static
+ in this case because we protect it with -hidden_symbol. */
+static func_ptr __CTOR_END__[];
+#ifdef EH_FRAME_SECTION_ASM_OP
+extern void __frame_dummy (void);
+#endif
+void
+__do_global_ctors (void)
+{
+ func_ptr *p;
+#ifdef EH_FRAME_SECTION_ASM_OP
+ __frame_dummy ();
+#endif
+ for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
+ (*p) ();
+}
+#endif
+
#endif /* defined(INIT_SECTION_ASM_OP) */
/* Force cc1 to switch to .data section. */
-static func_ptr force_to_data[0] = { };
+static func_ptr force_to_data[0] __attribute__ ((__unused__)) = { };
+
+/* Put a word containing zero at the end of each of our two lists of function
+ addresses. Note that the words defined here go into the .ctors and .dtors
+ sections of the crtend.o file, and since that file is always linked in
+ last, these words naturally end up at the very ends of the two lists
+ contained in these two sections. */
#ifdef CTOR_LIST_END
CTOR_LIST_END;
#else
asm (CTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
-func_ptr __CTOR_END__[1] = { (func_ptr) 0 };
+STATIC func_ptr __CTOR_END__[1] = { (func_ptr) 0 };
#endif
#ifdef DTOR_LIST_END
DTOR_LIST_END;
#else
asm (DTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */
-func_ptr __DTOR_END__[1] = { (func_ptr) 0 };
+STATIC func_ptr __DTOR_END__[1] __attribute__ ((__unused__))
+ = { (func_ptr) 0 };
#endif
+#ifdef EH_FRAME_SECTION_ASM_OP
+/* Terminate the frame unwind info section with a 4byte 0 as a sentinel;
+ this would be the 'length' field in a real FDE. */
+
+typedef unsigned int ui32 __attribute__ ((mode (SI)));
+asm (EH_FRAME_SECTION_ASM_OP);
+STATIC ui32 __FRAME_END__[] __attribute__ ((__unused__)) = { 0 };
+#endif /* EH_FRAME_SECTION */
+
#endif /* defined(CRT_END) */
+
+#else /* OBJECT_FORMAT_MACHO */
+
+/* For Mach-O format executables, we assume that the system's runtime is
+ smart enough to handle constructors and destructors, but doesn't have
+ an init section (if it can't even handle constructors/destructors
+ you should be using INVOKE__main, not crtstuff). All we need to do
+ is install/deinstall the frame information for exceptions. We do this
+ by putting a constructor in crtbegin.o and a destructor in crtend.o.
+
+ crtend.o also puts in the terminating zero in the frame information
+ segment. */
+
+/* The crtstuff for other object formats use the symbol __EH_FRAME_BEGIN__
+ to figure out the start of the exception frame, but here we use
+ getsectbynamefromheader to find this value. Either method would work,
+ but this method avoids creating any global symbols, which seems
+ cleaner. */
+
+#include <mach-o/ldsyms.h>
+extern const struct section *
+ getsectbynamefromheader (const struct mach_header *,
+ const char *, const char *);
+
+#ifdef CRT_BEGIN
+
+static void __reg_frame_ctor (void) __attribute__ ((constructor));
+
+static void
+__reg_frame_ctor (void)
+{
+ static struct object object;
+ const struct section *eh_frame;
+
+ eh_frame = getsectbynamefromheader (&_mh_execute_header,
+ "__TEXT", "__eh_frame");
+ __register_frame_info ((void *) eh_frame->addr, &object);
+}
+
+#endif /* CRT_BEGIN */
+
+#ifdef CRT_END
+
+static void __dereg_frame_dtor (void) __attribute__ ((destructor));
+
+static void
+__dereg_frame_dtor (void)
+{
+ const struct section *eh_frame;
+
+ eh_frame = getsectbynamefromheader (&_mh_execute_header,
+ "__TEXT", "__eh_frame");
+ __deregister_frame_info ((void *) eh_frame->addr);
+}
+
+/* Terminate the frame section with a final zero. */
+
+/* Force cc1 to switch to .data section. */
+static void * force_to_data[0] __attribute__ ((__unused__)) = { };
+
+typedef unsigned int ui32 __attribute__ ((mode (SI)));
+asm (EH_FRAME_SECTION_ASM_OP);
+static ui32 __FRAME_END__[] __attribute__ ((__unused__)) = { 0 };
+
+#endif /* CRT_END */
+
+#endif /* OBJECT_FORMAT_MACHO */
+
OSDN Git Service
