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/* Copyright (C) 2004-2023 Free Software Foundation, Inc.
Contributed by Douglas B Rupp <>
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
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
<>. */
/* 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"
#include <ossddef.h>
#ifndef SS$_NORMAL
#define SS$_NORMAL 1
#define UNW_IVMS_MODE(HEADER) (((HEADER) >> 44) & 0x3L)
typedef struct
unw_word start_offset;
unw_word end_offset;
unw_word info_offset;
unw_word 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),
/* 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. */
+ 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$v_type == OSSD$K_GENERAL_INFO
&& (ossd->ossd$v_exception_frame
|| ossd->ossd$v_bottom_of_stack || ossd->ossd$v_base_frame);
/* Return a pointer to the unwind table entry for the function
containing PC, 0 if we cannot find an entry or if the one we find
calls for fallback processing. */
struct unw_table_entry *
_Unwind_FindTableEntry (void *pc, unw_word *segment_base,
unw_word *gp, struct unw_table_entry *ent)
vms_unw_table_entry vueblock;
if (SYS$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;