libgcc/config/vxcrtstuff.c

/* This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.

You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
<http://www.gnu.org/licenses/>.  */

/* The essential point of the crtbegin/crtend files on VxWorks is to handle
   the eh frames registration thanks to dedicated constructors and
   destructors.  What needs to be done depends on the VxWorks version and the
   kind of module (rtp, dkm, ...) one is building.  */

#define IN_LIBGCC2

#include "auto-host.h"
#include "tconfig.h"
#include "tsystem.h"
#include "coretypes.h"
#include "tm.h"
#include "libgcc_tm.h"
#include "unwind-dw2-fde.h"

/* If we are entitled/requested to use init/fini arrays, we'll rely on that.
   Otherwise, we may rely on ctors/dtors sections for RTPs or expect munch to
   be involved for kernel modules.  */

#if !defined(USE_INITFINI_ARRAY) && defined(__RTP__)
#define USE_CDTORS_SECTIONS
#endif

/*  ------------------------------ crtbegin -------------------------------  */

#ifdef CRT_BEGIN

/* Stick a label at the beginning of the frame unwind info so we can register
   and deregister it with the exception handling library code.  */
static const char __EH_FRAME_BEGIN__[]
__attribute__((section(__LIBGCC_EH_FRAME_SECTION_NAME__), aligned(4)))
  = { };

/* Determine what names to use for the constructor/destructor functions.  */

#if defined(USE_CDTORS_SECTIONS) || defined(USE_INITFINI_ARRAY)

#define EH_CTOR_NAME _crtbe_register_frame
#define EH_DTOR_NAME _ctrbe_deregister_frame

#else

/* No specific sections for constructors or destructors: we thus use a
   symbol naming convention so that the constructors are then recognized
   by munch or whatever tool is used for the final link phase.  */
#define EH_CTOR_NAME _GLOBAL__I_00101_0__crtbe_register_frame
#define EH_DTOR_NAME _GLOBAL__D_00101_1__crtbe_deregister_frame

#endif

#ifdef USE_INITFINI_ARRAY
/* .init_array and .fini_array is supported starting VxWorks 7.2 in all
   cases. The compiler is then configured to always support priorities in
   constructors, so we can rely on the constructor and destructor attributes
   to generate the proper sections.  */
#define EH_CTOR_ATTRIBUTE __attribute__((constructor (101)))
#define EH_DTOR_ATTRIBUTE __attribute__((destructor (101)))

#else /* !USE_INITFINI_ARRAY  */

/* Note: Even in case of .ctors/.dtors sections, we can't use the attribute
   (constructor (15)) here as gcc may have been configured with constructors
   priority disabled.  We will instead craft an explicit section name for this
   purpose.  */
#define EH_CTOR_ATTRIBUTE
#define EH_DTOR_ATTRIBUTE

#endif /* USE_INITFINI_ARRAY  */

void EH_CTOR_NAME (void);
void EH_DTOR_NAME (void);

EH_CTOR_ATTRIBUTE void EH_CTOR_NAME (void)
{
  static struct object object;
  __register_frame_info (__EH_FRAME_BEGIN__, &object);
}

EH_DTOR_ATTRIBUTE void EH_DTOR_NAME (void)
{
  __deregister_frame_info (__EH_FRAME_BEGIN__);
}

#ifdef USE_CDTORS_SECTIONS
/* As explained above, we need to manually build the sections here as the
   compiler may not have support for constructors priority enabled.  */
static void (* volatile eh_registration_ctors[])()
  __attribute__((section (".ctors.101")))
= { &EH_CTOR_NAME };
static void (* volatile eh_registration_dtors[])()
  __attribute__((section (".dtors.65434")))
= { &EH_DTOR_NAME };
#endif

/*  ------------------------------ crtend ---------------------------------  */

#elif defined (CRT_END) /* ! CRT_BEGIN */

/* Terminate the frame unwind info section with a 4byte 0 as a sentinel;
   this would be the 'length' field in a real FDE.  */

static const char __FRAME_END__[]
     __attribute__ ((used, section(__LIBGCC_EH_FRAME_SECTION_NAME__),
		     aligned(4)))
  = { 0, 0, 0, 0 };

#else /* ! CRT_BEGIN & ! CRT_END */

#error "One of CRT_BEGIN or CRT_END must be defined."

#endif