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
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
29struct frame_unwind_cache
30{
31  struct regcache *regcache;
32};
33
34void *
35sentinel_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
45static void
46sentinel_frame_prev_register (struct frame_info *next_frame,
47			      void **this_prologue_cache,
48			      int regnum, int *optimized,
49			      enum lval_type *lvalp, CORE_ADDR *addrp,
50			      int *realnum, gdb_byte *bufferp)
51{
52  struct frame_unwind_cache *cache = *this_prologue_cache;
53  /* Describe the register's location.  A reg-frame maps all registers
54     onto the corresponding hardware register.  */
55  *optimized = 0;
56  *lvalp = lval_register;
57  *addrp = register_offset_hack (current_gdbarch, regnum);
58  *realnum = regnum;
59
60  /* If needed, find and return the value of the register.  */
61  if (bufferp != NULL)
62    {
63      /* Return the actual value.  */
64      /* Use the regcache_cooked_read() method so that it, on the fly,
65         constructs either a raw or pseudo register from the raw
66         register cache.  */
67      regcache_cooked_read (cache->regcache, regnum, bufferp);
68    }
69}
70
71static void
72sentinel_frame_this_id (struct frame_info *next_frame,
73			void **this_prologue_cache,
74			struct frame_id *this_id)
75{
76  /* The sentinel frame is used as a starting point for creating the
77     previous (inner most) frame.  That frame's THIS_ID method will be
78     called to determine the inner most frame's ID.  Not this one.  */
79  internal_error (__FILE__, __LINE__, _("sentinel_frame_this_id called"));
80}
81
82static CORE_ADDR
83sentinel_frame_prev_pc (struct frame_info *next_frame,
84			void **this_prologue_cache)
85{
86  struct gdbarch *gdbarch = get_frame_arch (next_frame);
87  return gdbarch_unwind_pc (gdbarch, next_frame);
88}
89
90const struct frame_unwind sentinel_frame_unwinder =
91{
92  SENTINEL_FRAME,
93  sentinel_frame_this_id,
94  sentinel_frame_prev_register,
95  NULL, /* unwind_data */
96  NULL, /* sniffer */
97  sentinel_frame_prev_pc,
98};
99
100const struct frame_unwind *const sentinel_frame_unwind = &sentinel_frame_unwinder;
101