--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/config/ia64/fde-vms.c	Fri Feb 12 23:39:51 2010 +0900
@@ -0,0 +1,157 @@
+/* Copyright (C) 2004, 2009 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 <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
+
+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;
+}