libgcc/config/alpha/vms-gcc_shell_handler.c

   1 /* Static condition handler for Alpha/VMS.
   2    Copyright (C) 2005-2018 Free Software Foundation, Inc.
   3
   4    This file is part of GCC.
   5
   6    GCC is free software; you can redistribute it and/or modify it
   7    under the terms of the GNU General Public License as published
   8    by the Free Software Foundation; either version 3, or (at your
   9    option) any later version.
  10
  11    GCC is distributed in the hope that it will be useful, but WITHOUT
  12    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  13    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  14    License for more details.
  15
  16    Under Section 7 of GPL version 3, you are granted additional
  17    permissions described in the GCC Runtime Library Exception, version
  18    3.1, as published by the Free Software Foundation.
  19
  20    You should have received a copy of the GNU General Public License and
  21    a copy of the GCC Runtime Library Exception along with this program;
  22    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23    <http://www.gnu.org/licenses/>.  */
  24
  25 /* This file implements __gcc_shell_handler, the static VMS condition handler
  26    used as the indirection wrapper around user level handlers installed with
  27    establish_vms_condition_handler GCC builtin.
  28
  29    [ABI] in comments refers to the "HP OpenVMS calling standard" document
  30    dated January 2005.  */
  31
  32 #include <vms/chfdef.h>
  33 #include <vms/pdscdef.h>
  34 #include <vms/ssdef.h>
  35
  36 typedef void * ADDR;
  37 typedef unsigned long long REG;
  38
  39 #define REG_AT(addr) (*(REG *)(addr))
  40
  41 /* Compute pointer to procedure descriptor (Procedure Value) from Frame
  42    Pointer FP, according to the rules in [ABI-3.5.1 Current Procedure].  */
  43 #define PV_FOR(FP) \
  44   (((FP) != 0) \
  45     ? (((REG_AT (FP) & 0x7) == 0) ? *(PDSCDEF **)(FP) : (PDSCDEF *)(FP)) : 0)
  46
  47 long
  48 __gcc_shell_handler (struct chf$signal_array *sig_arr,
  49                      struct chf$mech_array *mech_arr);
  50
  51 /* Helper for __gcc_shell_handler.  Fetch the pointer to procedure currently
  52    registered as the VMS condition handler for the live function with a frame
  53    pointer FP.  */
  54
  55 static ADDR
  56 get_dyn_handler_pointer (REG fp)
  57 {
  58   /* From the frame pointer we find the procedure descriptor, and fetch
  59      the handler_data field from there.  This field contains the offset
  60      from FP at which the address of the currently installed handler is
  61      to be found.  */
  62
  63   PDSCDEF * pd = PV_FOR (fp);
  64   /* Procedure descriptor pointer for the live subprogram with FP as the frame
  65      pointer, and to which _gcc_shell_handler is attached as a condition
  66      handler.  */
  67
  68   REG handler_slot_offset;
  69   /* Offset from FP at which the address of the currently established real
  70      condition handler is to be found.  This offset is available from the
  71      handler_data field of the procedure descriptor.  */
  72
  73   REG handler_data_offset;
  74   /* The handler_data field position in the procedure descriptor, which
  75      depends on the kind of procedure at hand.  */
  76
  77   switch (pd->pdsc$w_flags & 0xf)
  78     {
  79     case PDSC$K_KIND_FP_STACK:    /* [3.4.2 PD for stack frame procedures]  */
  80       handler_data_offset = 40;
  81       break;
  82
  83     case PDSC$K_KIND_FP_REGISTER: /* [3.4.5 PD for reg frame procedures]  */
  84       handler_data_offset = 32;
  85       break;
  86
  87     default:
  88       handler_data_offset = 0;
  89       break;
  90     }
  91
  92   /* If we couldn't determine the handler_data field position, give up.  */
  93   if (handler_data_offset == 0)
  94     return 0;
  95
  96   /* Otherwise, fetch the fp offset at which the real handler address is to be
  97      found, then fetch and return the latter in turn.  */
  98
  99   handler_slot_offset = REG_AT ((REG)pd + handler_data_offset);
 100
 101   return (ADDR) REG_AT (fp + handler_slot_offset);
 102 }
 103
 104 /* The static VMS condition handler for GCC code.  Fetch the address of the
 105    currently established condition handler, then resignal if there is none or
 106    call the handler with the VMS condition arguments.  */
 107
 108 long
 109 __gcc_shell_handler (struct chf$signal_array *sig_arr,
 110                      struct chf$mech_array *mech_arr)
 111 {
 112   long ret;
 113   long (*user_handler) (struct chf$signal_array *, struct chf$mech_array *);
 114
 115   user_handler = get_dyn_handler_pointer (mech_arr->chf$q_mch_frame);
 116   if (!user_handler)
 117     ret = SS$_RESIGNAL;
 118   else
 119     ret = user_handler (sig_arr, mech_arr);
 120
 121   return ret;
 122 }
 123