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/* Copyright (C) 2004, 2009, 2011 Free Software Foundation, Inc.

   Contributed by Douglas B Rupp <rupp@gnat.com>

   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/>.  */

/* Locate the FDE entry for a given address, using VMS Starlet routines

   to avoid register/deregister calls at DSO load/unload.  */

#include "tconfig.h"

#include "tsystem.h"

#include "coretypes.h"

#include "tm.h"

#include "libgcc_tm.h"

#include <stddef.h>

#include <stdlib.h>

#include <stdio.h>

#include "unwind-ia64.h"

#define __int64 long

#include <vms/ossddef.h>

#ifndef SS$_NORMAL

#define SS$_NORMAL 1

#endif

#define UNW_IVMS_MODE(HEADER) (((HEADER) >> 44) & 0x3L)

typedef struct

{

  unsigned long start_offset;

  unsigned long end_offset;

  unsigned long info_offset;

  unsigned long gp_value;

}  vms_unw_table_entry;

typedef unsigned long long uqword;

/* ENTRY is the unwind table entry found for a PC part of call chain we're

   unwinding through.  Return whether we should force the generic unwinder

   to resort to "fallback" processing.  */

static int

force_fallback_processing_for (void * pc, vms_unw_table_entry * entry)

{

  static int eh_debug = -1;

  uqword * unw_info_block = (uqword *)entry->info_offset;

  uqword header = *unw_info_block;

  /* We need to force fallback processing in two cases:

     1/ The exception dispatch frame, since only our fallback

        processing knows how to properly unwind through it, and

     2/ A bottom of stack frame, since only our fallback processing

        will ensure we don't try to unwind further past it, which

        would get us into unknown territory and likely cause a severe

        crash along the way.

     The two cases are indicated by non-default values for specific

     bits in the OS Specific Data (OSSD) General Information block

     associated with such frames.  */

  ossddef * ossd;

  if (eh_debug == -1)

    {

      char * EH_DEBUG = getenv ("EH_DEBUG");

      eh_debug = EH_DEBUG ? atoi (EH_DEBUG) : 0;

    }

  if (eh_debug)

    {

      printf ("pc @ 0x%p, block @ 0x%p, header = 0x%016llx\n",

              pc, unw_info_block, header);

      printf ("mode = %d, length = %ld, handler = %d\n",

              (int)UNW_IVMS_MODE (header), UNW_LENGTH (header),

              UNW_FLAG_EHANDLER (header) || UNW_FLAG_EHANDLER (header));

    }

  /* An OSSD block is there for IVMS_MODE == 3 only.  */

  if (UNW_IVMS_MODE (header) != 3)

    return 0;

  /* The OSSD block is found past the header, unwind descriptor area

     and condition handler pointer, if any.  */

  ossd = (ossddef *)

    /* Beware: uqword pointer arithmetic below.  */

    (unw_info_block

     + 1

     + UNW_LENGTH (header)

     + (UNW_FLAG_EHANDLER (header) || UNW_FLAG_EHANDLER (header)));

  /* "A General Information segment may be omitted if all of its fields

      would have their default values.  If a General Information segment

      is present, it must be the first in the OSSD area."  So ...  */

  if (eh_debug)

    printf ("ossd @ 0x%p\n", ossd);

  if (eh_debug && ossd->ossd$v_type == OSSD$K_GENERAL_INFO)

    printf ("exc_frame = %d - bot_frame = %d - base_frame = %d\n",

            ossd->ossd$v_exception_frame,

            ossd->ossd$v_bottom_of_stack,

            ossd->ossd$v_base_frame);

  return

    ossd->ossd$v_type == OSSD$K_GENERAL_INFO

    && (ossd->ossd$v_exception_frame

        || ossd->ossd$v_bottom_of_stack || ossd->ossd$v_base_frame);

}

/* Return a pointer to the unwind table entry for the function

   containing PC, 0 if we cannot find an entry or if the one we find

   calls for fallback processing.  */

struct unw_table_entry *

_Unwind_FindTableEntry (void *pc, unsigned long *segment_base,

                        unsigned long *gp, struct unw_table_entry *ent)

{

  vms_unw_table_entry vueblock;

  if (SYS$GET_UNWIND_ENTRY_INFO (pc, &vueblock, 0) != SS$_NORMAL)

    return 0;

  /* If there is no unwind information, use fallback.  */

  if (vueblock.info_offset == 0)

    return 0;

  /* If we need to force fallback processing, just pretend there is

     no entry.  */

  if (force_fallback_processing_for (pc, &vueblock))

    return 0;

  *segment_base = 0; /* ??? Fixme. ??? */

  *gp = vueblock.gp_value;

  ent->start_offset = vueblock.start_offset;

  ent->end_offset = vueblock.end_offset;

  ent->info_offset = vueblock.info_offset;

  return ent;

}