gdb/sentinel-frame.c

   1 /* Code dealing with register stack frames, for GDB, the GNU debugger.
   2
   3    Copyright (C) 1986-2017 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20
  21 #include "defs.h"
  22 #include "regcache.h"
  23 #include "sentinel-frame.h"
  24 #include "inferior.h"
  25 #include "frame-unwind.h"
  26
  27 struct frame_unwind_cache
  28 {
  29   struct regcache *regcache;
  30 };
  31
  32 void *
  33 sentinel_frame_cache (struct regcache *regcache)
  34 {
  35   struct frame_unwind_cache *cache =
  36     FRAME_OBSTACK_ZALLOC (struct frame_unwind_cache);
  37
  38   cache->regcache = regcache;
  39   return cache;
  40 }
  41
  42 /* Here the register value is taken direct from the register cache.  */
  43
  44 static struct value *
  45 sentinel_frame_prev_register (struct frame_info *this_frame,
  46                               void **this_prologue_cache,
  47                               int regnum)
  48 {
  49   struct frame_unwind_cache *cache
  50     = (struct frame_unwind_cache *) *this_prologue_cache;
  51   struct value *value;
  52
  53   value = regcache_cooked_read_value (cache->regcache, regnum);
  54   VALUE_NEXT_FRAME_ID (value) = sentinel_frame_id;
  55
  56   return value;
  57 }
  58
  59 static void
  60 sentinel_frame_this_id (struct frame_info *this_frame,
  61                         void **this_prologue_cache,
  62                         struct frame_id *this_id)
  63 {
  64   /* The sentinel frame is used as a starting point for creating the
  65      previous (inner most) frame.  That frame's THIS_ID method will be
  66      called to determine the inner most frame's ID.  Not this one.  */
  67   internal_error (__FILE__, __LINE__, _("sentinel_frame_this_id called"));
  68 }
  69
  70 static struct gdbarch *
  71 sentinel_frame_prev_arch (struct frame_info *this_frame,
  72                           void **this_prologue_cache)
  73 {
  74   struct frame_unwind_cache *cache
  75     = (struct frame_unwind_cache *) *this_prologue_cache;
  76
  77   return cache->regcache->arch ();
  78 }
  79
  80 const struct frame_unwind sentinel_frame_unwind =
  81 {
  82   SENTINEL_FRAME,
  83   default_frame_unwind_stop_reason,
  84   sentinel_frame_this_id,
  85   sentinel_frame_prev_register,
  86   NULL,
  87   NULL,
  88   NULL,
  89   sentinel_frame_prev_arch,
  90 };