gdb/frame-unwind.c

   1 /* Definitions for frame unwinder, for GDB, the GNU debugger.
   2
   3    Copyright (C) 2003, 2004, 2007, 2008, 2009 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 #include "defs.h"
  21 #include "frame.h"
  22 #include "frame-unwind.h"
  23 #include "dummy-frame.h"
  24 #include "value.h"
  25 #include "regcache.h"
  26
  27 #include "gdb_assert.h"
  28 #include "gdb_obstack.h"
  29
  30 static struct gdbarch_data *frame_unwind_data;
  31
  32 struct frame_unwind_table_entry
  33 {
  34   const struct frame_unwind *unwinder;
  35   struct frame_unwind_table_entry *next;
  36 };
  37
  38 struct frame_unwind_table
  39 {
  40   struct frame_unwind_table_entry *list;
  41   /* The head of the OSABI part of the search list.  */
  42   struct frame_unwind_table_entry **osabi_head;
  43 };
  44
  45 static void *
  46 frame_unwind_init (struct obstack *obstack)
  47 {
  48   struct frame_unwind_table *table
  49     = OBSTACK_ZALLOC (obstack, struct frame_unwind_table);
  50   /* Start the table out with a few default sniffers.  OSABI code
  51      can't override this.  */
  52   table->list = OBSTACK_ZALLOC (obstack, struct frame_unwind_table_entry);
  53   table->list->unwinder = dummy_frame_unwind;
  54   /* The insertion point for OSABI sniffers.  */
  55   table->osabi_head = &table->list->next;
  56   return table;
  57 }
  58
  59 void
  60 frame_unwind_prepend_unwinder (struct gdbarch *gdbarch,
  61                                 const struct frame_unwind *unwinder)
  62 {
  63   struct frame_unwind_table *table = gdbarch_data (gdbarch, frame_unwind_data);
  64   struct frame_unwind_table_entry *entry;
  65
  66   /* Insert the new entry at the start of the list.  */
  67   entry = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind_table_entry);
  68   entry->unwinder = unwinder;
  69   entry->next = (*table->osabi_head);
  70   (*table->osabi_head) = entry;
  71 }
  72
  73 void
  74 frame_unwind_append_unwinder (struct gdbarch *gdbarch,
  75                               const struct frame_unwind *unwinder)
  76 {
  77   struct frame_unwind_table *table = gdbarch_data (gdbarch, frame_unwind_data);
  78   struct frame_unwind_table_entry **ip;
  79
  80   /* Find the end of the list and insert the new entry there.  */
  81   for (ip = table->osabi_head; (*ip) != NULL; ip = &(*ip)->next);
  82   (*ip) = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind_table_entry);
  83   (*ip)->unwinder = unwinder;
  84 }
  85
  86 const struct frame_unwind *
  87 frame_unwind_find_by_frame (struct frame_info *this_frame, void **this_cache)
  88 {
  89   int i;
  90   struct gdbarch *gdbarch = get_frame_arch (this_frame);
  91   struct frame_unwind_table *table = gdbarch_data (gdbarch, frame_unwind_data);
  92   struct frame_unwind_table_entry *entry;
  93   struct cleanup *old_cleanup;
  94   for (entry = table->list; entry != NULL; entry = entry->next)
  95     {
  96       struct cleanup *old_cleanup;
  97
  98       old_cleanup = frame_prepare_for_sniffer (this_frame, entry->unwinder);
  99       if (entry->unwinder->sniffer (entry->unwinder, this_frame,
 100                                     this_cache))
 101         {
 102           discard_cleanups (old_cleanup);
 103           return entry->unwinder;
 104         }
 105       do_cleanups (old_cleanup);
 106     }
 107   internal_error (__FILE__, __LINE__, _("frame_unwind_find_by_frame failed"));
 108 }
 109
 110 /* A default frame sniffer which always accepts the frame.  Used by
 111    fallback prologue unwinders.  */
 112
 113 int
 114 default_frame_sniffer (const struct frame_unwind *self,
 115                        struct frame_info *this_frame,
 116                        void **this_prologue_cache)
 117 {
 118   return 1;
 119 }
 120
 121 /* Helper functions for value-based register unwinding.  These return
 122    a (possibly lazy) value of the appropriate type.  */
 123
 124 /* Return a value which indicates that FRAME did not save REGNUM.  */
 125
 126 struct value *
 127 frame_unwind_got_optimized (struct frame_info *frame, int regnum)
 128 {
 129   struct gdbarch *gdbarch = get_frame_arch (frame);
 130   struct value *reg_val;
 131
 132   reg_val = value_zero (register_type (gdbarch, regnum), not_lval);
 133   set_value_optimized_out (reg_val, 1);
 134   return reg_val;
 135 }
 136
 137 /* Return a value which indicates that FRAME copied REGNUM into
 138    register NEW_REGNUM.  */
 139
 140 struct value *
 141 frame_unwind_got_register (struct frame_info *frame, int regnum, int new_regnum)
 142 {
 143   return value_of_register_lazy (frame, new_regnum);
 144 }
 145
 146 /* Return a value which indicates that FRAME saved REGNUM in memory at
 147    ADDR.  */
 148
 149 struct value *
 150 frame_unwind_got_memory (struct frame_info *frame, int regnum, CORE_ADDR addr)
 151 {
 152   struct gdbarch *gdbarch = get_frame_arch (frame);
 153
 154   return value_at_lazy (register_type (gdbarch, regnum), addr);
 155 }
 156
 157 /* Return a value which indicates that FRAME's saved version of
 158    REGNUM has a known constant (computed) value of VAL.  */
 159
 160 struct value *
 161 frame_unwind_got_constant (struct frame_info *frame, int regnum,
 162                            ULONGEST val)
 163 {
 164   struct gdbarch *gdbarch = get_frame_arch (frame);
 165   struct value *reg_val;
 166
 167   reg_val = value_zero (register_type (gdbarch, regnum), not_lval);
 168   store_unsigned_integer (value_contents_writeable (reg_val),
 169                           register_size (gdbarch, regnum), val);
 170   return reg_val;
 171 }
 172
 173 struct value *
 174 frame_unwind_got_bytes (struct frame_info *frame, int regnum, gdb_byte *buf)
 175 {
 176   struct gdbarch *gdbarch = get_frame_arch (frame);
 177   struct value *reg_val;
 178
 179   reg_val = value_zero (register_type (gdbarch, regnum), not_lval);
 180   memcpy (value_contents_raw (reg_val), buf, register_size (gdbarch, regnum));
 181   return reg_val;
 182 }
 183
 184 /* Return a value which indicates that FRAME's saved version of REGNUM
 185    has a known constant (computed) value of ADDR.  Convert the
 186    CORE_ADDR to a target address if necessary.  */
 187
 188 struct value *
 189 frame_unwind_got_address (struct frame_info *frame, int regnum,
 190                           CORE_ADDR addr)
 191 {
 192   struct gdbarch *gdbarch = get_frame_arch (frame);
 193   struct value *reg_val;
 194
 195   reg_val = value_zero (register_type (gdbarch, regnum), not_lval);
 196   pack_long (value_contents_writeable (reg_val),
 197              register_type (gdbarch, regnum), addr);
 198   return reg_val;
 199 }
 200
 201 extern initialize_file_ftype _initialize_frame_unwind; /* -Wmissing-prototypes */
 202
 203 void
 204 _initialize_frame_unwind (void)
 205 {
 206   frame_unwind_data = gdbarch_data_register_pre_init (frame_unwind_init);
 207 }