gdb/sentinel-frame.c

   1 /* Code dealing with register stack frames, for GDB, the GNU debugger.
   2
   3    Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995,
   4    1996, 1997, 1998, 1999, 2000, 2001, 2002, 2007, 2008, 2009, 2010, 2011
   5    Free Software Foundation, Inc.
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  21
  22
  23 #include "defs.h"
  24 #include "regcache.h"
  25 #include "sentinel-frame.h"
  26 #include "inferior.h"
  27 #include "frame-unwind.h"
  28
  29 struct frame_unwind_cache
  30 {
  31   struct regcache *regcache;
  32 };
  33
  34 void *
  35 sentinel_frame_cache (struct regcache *regcache)
  36 {
  37   struct frame_unwind_cache *cache =
  38     FRAME_OBSTACK_ZALLOC (struct frame_unwind_cache);
  39
  40   cache->regcache = regcache;
  41   return cache;
  42 }
  43
  44 /* Here the register value is taken direct from the register cache.  */
  45
  46 static struct value *
  47 sentinel_frame_prev_register (struct frame_info *this_frame,
  48                               void **this_prologue_cache,
  49                               int regnum)
  50 {
  51   struct gdbarch *gdbarch = get_frame_arch (this_frame);
  52   struct frame_unwind_cache *cache = *this_prologue_cache;
  53   struct value *value;
  54
  55   /* Return the actual value.  */
  56   value = allocate_value (register_type (gdbarch, regnum));
  57   VALUE_LVAL (value) = lval_register;
  58   VALUE_REGNUM (value) = regnum;
  59   VALUE_FRAME_ID (value) = get_frame_id (this_frame);
  60
  61   /* Use the regcache_cooked_read() method so that it, on the fly,
  62      constructs either a raw or pseudo register from the raw
  63      register cache.  */
  64   if (regcache_cooked_read (cache->regcache,
  65                             regnum,
  66                             value_contents_raw (value)) == REG_UNAVAILABLE)
  67     mark_value_bytes_unavailable (value, 0, register_size (gdbarch, regnum));
  68
  69   return value;
  70 }
  71
  72 static void
  73 sentinel_frame_this_id (struct frame_info *this_frame,
  74                         void **this_prologue_cache,
  75                         struct frame_id *this_id)
  76 {
  77   /* The sentinel frame is used as a starting point for creating the
  78      previous (inner most) frame.  That frame's THIS_ID method will be
  79      called to determine the inner most frame's ID.  Not this one.  */
  80   internal_error (__FILE__, __LINE__, _("sentinel_frame_this_id called"));
  81 }
  82
  83 static struct gdbarch *
  84 sentinel_frame_prev_arch (struct frame_info *this_frame,
  85                           void **this_prologue_cache)
  86 {
  87   struct frame_unwind_cache *cache = *this_prologue_cache;
  88
  89   return get_regcache_arch (cache->regcache);
  90 }
  91
  92 const struct frame_unwind sentinel_frame_unwind =
  93 {
  94   SENTINEL_FRAME,
  95   sentinel_frame_this_id,
  96   sentinel_frame_prev_register,
  97   NULL,
  98   NULL,
  99   NULL,
 100   sentinel_frame_prev_arch,
 101 };