gdb/sentinel-frame.c

   1 /* Code dealing with register stack frames, for GDB, the GNU debugger.
   2
   3    Copyright (C) 1986-2023 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 (frame_info_ptr 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   frame_id this_frame_id = get_frame_id (this_frame);
  54   gdb_assert (is_sentinel_frame_id (this_frame_id));
  55
  56   value = cache->regcache->cooked_read_value (regnum);
  57   VALUE_NEXT_FRAME_ID (value) = this_frame_id;
  58
  59   return value;
  60 }
  61
  62 static void
  63 sentinel_frame_this_id (frame_info_ptr this_frame,
  64                         void **this_prologue_cache,
  65                         struct frame_id *this_id)
  66 {
  67   /* The sentinel frame is used as a starting point for creating the
  68      previous (inner most) frame.  That frame's THIS_ID method will be
  69      called to determine the inner most frame's ID.  Not this one.  */
  70   internal_error (_("sentinel_frame_this_id called"));
  71 }
  72
  73 static struct gdbarch *
  74 sentinel_frame_prev_arch (frame_info_ptr this_frame,
  75                           void **this_prologue_cache)
  76 {
  77   struct frame_unwind_cache *cache
  78     = (struct frame_unwind_cache *) *this_prologue_cache;
  79
  80   return cache->regcache->arch ();
  81 }
  82
  83 const struct frame_unwind sentinel_frame_unwind =
  84 {
  85   "sentinel",
  86   SENTINEL_FRAME,
  87   default_frame_unwind_stop_reason,
  88   sentinel_frame_this_id,
  89   sentinel_frame_prev_register,
  90   NULL,
  91   NULL,
  92   NULL,
  93   sentinel_frame_prev_arch,
  94 };