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
   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 void
  46 sentinel_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
  71 static void
  72 sentinel_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
  82 static CORE_ADDR
  83 sentinel_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
  90 const 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
 100 const struct frame_unwind *const sentinel_frame_unwind = &sentinel_frame_unwinder;