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,
   4    1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002 Free Software
   5    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 2 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, write to the Free Software
  21    Foundation, Inc., 51 Franklin Street, Fifth Floor,
  22    Boston, MA 02110-1301, USA.  */
  23
  24
  25 #include "defs.h"
  26 #include "regcache.h"
  27 #include "sentinel-frame.h"
  28 #include "inferior.h"
  29 #include "frame-unwind.h"
  30
  31 struct frame_unwind_cache
  32 {
  33   struct regcache *regcache;
  34 };
  35
  36 void *
  37 sentinel_frame_cache (struct regcache *regcache)
  38 {
  39   struct frame_unwind_cache *cache =
  40     FRAME_OBSTACK_ZALLOC (struct frame_unwind_cache);
  41   cache->regcache = regcache;
  42   return cache;
  43 }
  44
  45 /* Here the register value is taken direct from the register cache.  */
  46
  47 static void
  48 sentinel_frame_prev_register (struct frame_info *next_frame,
  49                               void **this_prologue_cache,
  50                               int regnum, int *optimized,
  51                               enum lval_type *lvalp, CORE_ADDR *addrp,
  52                               int *realnum, gdb_byte *bufferp)
  53 {
  54   struct frame_unwind_cache *cache = *this_prologue_cache;
  55   /* Describe the register's location.  A reg-frame maps all registers
  56      onto the corresponding hardware register.  */
  57   *optimized = 0;
  58   *lvalp = lval_register;
  59   *addrp = register_offset_hack (current_gdbarch, regnum);
  60   *realnum = regnum;
  61
  62   /* If needed, find and return the value of the register.  */
  63   if (bufferp != NULL)
  64     {
  65       /* Return the actual value.  */
  66       /* Use the regcache_cooked_read() method so that it, on the fly,
  67          constructs either a raw or pseudo register from the raw
  68          register cache.  */
  69       regcache_cooked_read (cache->regcache, regnum, bufferp);
  70     }
  71 }
  72
  73 static void
  74 sentinel_frame_this_id (struct frame_info *next_frame,
  75                         void **this_prologue_cache,
  76                         struct frame_id *this_id)
  77 {
  78   /* The sentinel frame is used as a starting point for creating the
  79      previous (inner most) frame.  That frame's THIS_ID method will be
  80      called to determine the inner most frame's ID.  Not this one.  */
  81   internal_error (__FILE__, __LINE__, _("sentinel_frame_this_id called"));
  82 }
  83
  84 static CORE_ADDR
  85 sentinel_frame_prev_pc (struct frame_info *next_frame,
  86                         void **this_prologue_cache)
  87 {
  88   struct gdbarch *gdbarch = get_frame_arch (next_frame);
  89   return gdbarch_unwind_pc (gdbarch, next_frame);
  90 }
  91
  92 const struct frame_unwind sentinel_frame_unwinder =
  93 {
  94   SENTINEL_FRAME,
  95   sentinel_frame_this_id,
  96   sentinel_frame_prev_register,
  97   NULL, /* unwind_data */
  98   NULL, /* sniffer */
  99   sentinel_frame_prev_pc,
 100 };
 101
 102 const struct frame_unwind *const sentinel_frame_unwind = &sentinel_frame_unwinder;