gcc/config/alpha/vms-gcc_shell_handler.c

   1 /* Static condition handler for Alpha/VMS.
   2    Copyright (C) 2005-2009
   3    Free Software Foundation, Inc.
   4
   5    This file is part of GCC.
   6
   7    GCC is free software; you can redistribute it and/or modify it
   8    under the terms of the GNU General Public License as published
   9    by the Free Software Foundation; either version 3, or (at your
  10    option) any later version.
  11
  12    GCC is distributed in the hope that it will be useful, but WITHOUT
  13    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  14    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  15    License for more details.
  16
  17    Under Section 7 of GPL version 3, you are granted additional
  18    permissions described in the GCC Runtime Library Exception, version
  19    3.1, as published by the Free Software Foundation.
  20
  21    You should have received a copy of the GNU General Public License and
  22    a copy of the GCC Runtime Library Exception along with this program;
  23    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24    <http://www.gnu.org/licenses/>.  */
  25
  26 /* This file implements __gcc_shell_handler, the static VMS condition handler
  27    used as the indirection wrapper around user level handlers installed with
  28    establish_vms_condition_handler GCC builtin.
  29
  30    [ABI] in comments refers to the "HP OpenVMS calling standard" document
  31    dated January 2005.  */
  32
  33 #include <vms/chfdef.h>
  34 #include <vms/pdscdef.h>
  35 #include <vms/ssdef.h>
  36
  37 typedef void * ADDR;
  38 typedef unsigned long long REG;
  39
  40 #define REG_AT(addr) (*(REG *)(addr))
  41
  42 /* Compute pointer to procedure descriptor (Procedure Value) from Frame
  43    Pointer FP, according to the rules in [ABI-3.5.1 Current Procedure].  */
  44 #define PV_FOR(FP) \
  45   (((FP) != 0) \
  46     ? (((REG_AT (FP) & 0x7) == 0) ? *(PDSCDEF **)(FP) : (PDSCDEF *)(FP)) : 0)
  47
  48 long
  49 __gcc_shell_handler (struct chf$signal_array *sig_arr,
  50                      struct chf$mech_array *mech_arr);
  51
  52 /* Helper for __gcc_shell_handler.  Fetch the pointer to procedure currently
  53    registered as the VMS condition handler for the live function with a frame
  54    pointer FP.  */
  55
  56 static ADDR
  57 get_dyn_handler_pointer (REG fp)
  58 {
  59   /* From the frame pointer we find the procedure descriptor, and fetch
  60      the handler_data field from there.  This field contains the offset
  61      from FP at which the address of the currently installed handler is
  62      to be found.  */
  63
  64   PDSCDEF * pd = PV_FOR (fp);
  65   /* Procedure descriptor pointer for the live subprogram with FP as the frame
  66      pointer, and to which _gcc_shell_handler is attached as a condition
  67      handler.  */
  68
  69   REG handler_slot_offset;
  70   /* Offset from FP at which the address of the currently established real
  71      condition handler is to be found.  This offset is available from the
  72      handler_data field of the procedure descriptor.  */
  73
  74   REG handler_data_offset;
  75   /* The handler_data field position in the procedure descriptor, which
  76      depends on the kind of procedure at hand.  */
  77
  78   switch (pd->pdsc$w_flags & 0xf)
  79     {
  80     case PDSC$K_KIND_FP_STACK:    /* [3.4.2 PD for stack frame procedures]  */
  81       handler_data_offset = 40;
  82       break;
  83
  84     case PDSC$K_KIND_FP_REGISTER: /* [3.4.5 PD for reg frame procedures]  */
  85       handler_data_offset = 32;
  86       break;
  87
  88     default:
  89       handler_data_offset = 0;
  90       break;
  91     }
  92
  93   /* If we couldn't determine the handler_data field position, give up.  */
  94   if (handler_data_offset == 0)
  95     return 0;
  96
  97   /* Otherwise, fetch the fp offset at which the real handler address is to be
  98      found, then fetch and return the latter in turn.  */
  99
 100   handler_slot_offset = REG_AT ((REG)pd + handler_data_offset);
 101
 102   return (ADDR) REG_AT (fp + handler_slot_offset);
 103 }
 104
 105 /* The static VMS condition handler for GCC code.  Fetch the address of the
 106    currently established condition handler, then resignal if there is none or
 107    call the handler with the VMS condition arguments.  */
 108
 109 long
 110 __gcc_shell_handler (struct chf$signal_array *sig_arr,
 111                      struct chf$mech_array *mech_arr)
 112 {
 113   long ret;
 114   long (*user_handler) (struct chf$signal_array *, struct chf$mech_array *);
 115
 116   user_handler = get_dyn_handler_pointer (mech_arr->chf$q_mch_frame);
 117   if (!user_handler)
 118     ret = SS$_RESIGNAL;
 119   else
 120     ret = user_handler (sig_arr, mech_arr);
 121
 122   return ret;
 123 }
 124