1/* Code dealing with register stack frames, for GDB, the GNU debugger.
2
3   Copyright (C) 1986-2020 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
27struct frame_unwind_cache
28{
29  struct regcache *regcache;
30};
31
32void *
33sentinel_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
44static struct value *
45sentinel_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 = cache->regcache->cooked_read_value (regnum);
54  VALUE_NEXT_FRAME_ID (value) = sentinel_frame_id;
55
56  return value;
57}
58
59static void
60sentinel_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
70static struct gdbarch *
71sentinel_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
80const 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};
91