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
   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   cache->regcache = regcache;
  40   return cache;
  41 }
  42
  43 /* Here the register value is taken direct from the register cache.  */
  44
  45 static struct value *
  46 sentinel_frame_prev_register (struct frame_info *this_frame,
  47                               void **this_prologue_cache,
  48                               int regnum)
  49 {
  50   struct gdbarch *gdbarch = get_frame_arch (this_frame);
  51   struct frame_unwind_cache *cache = *this_prologue_cache;
  52   struct value *value;
  53
  54   /* Return the actual value.  */
  55   value = allocate_value (register_type (gdbarch, regnum));
  56   VALUE_LVAL (value) = lval_register;
  57   VALUE_REGNUM (value) = regnum;
  58   VALUE_FRAME_ID (value) = get_frame_id (this_frame);
  59
  60   /* Use the regcache_cooked_read() method so that it, on the fly,
  61      constructs either a raw or pseudo register from the raw
  62      register cache.  */
  63   regcache_cooked_read (cache->regcache, regnum, value_contents_raw (value));
  64
  65   return value;
  66 }
  67
  68 static void
  69 sentinel_frame_this_id (struct frame_info *this_frame,
  70                         void **this_prologue_cache,
  71                         struct frame_id *this_id)
  72 {
  73   /* The sentinel frame is used as a starting point for creating the
  74      previous (inner most) frame.  That frame's THIS_ID method will be
  75      called to determine the inner most frame's ID.  Not this one.  */
  76   internal_error (__FILE__, __LINE__, _("sentinel_frame_this_id called"));
  77 }
  78
  79 static struct gdbarch *
  80 sentinel_frame_prev_arch (struct frame_info *this_frame,
  81                           void **this_prologue_cache)
  82 {
  83   struct frame_unwind_cache *cache = *this_prologue_cache;
  84   return get_regcache_arch (cache->regcache);
  85 }
  86
  87 const struct frame_unwind sentinel_frame_unwinder =
  88 {
  89   SENTINEL_FRAME,
  90   sentinel_frame_this_id,
  91   sentinel_frame_prev_register,
  92   NULL,
  93   NULL,
  94   NULL,
  95   sentinel_frame_prev_arch,
  96 };
  97
  98 const struct frame_unwind *const sentinel_frame_unwind = &sentinel_frame_unwinder;