aboutsummaryrefslogtreecommitdiff
path: root/gdb/findvar.c
blob: 465e00a5bae1236c9379bc5c9cae493da4b7b1d3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
/* Find a variable's value in memory, for GDB, the GNU debugger.
   Copyright (C) 1986, 1987 Free Software Foundation, Inc.

GDB is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY.  No author or distributor accepts responsibility to anyone
for the consequences of using it or for whether it serves any
particular purpose or works at all, unless he says so in writing.
Refer to the GDB General Public License for full details.

Everyone is granted permission to copy, modify and redistribute GDB,
but only under the conditions described in the GDB General Public
License.  A copy of this license is supposed to have been given to you
along with GDB so you can know your rights and responsibilities.  It
should be in a file named COPYING.  Among other things, the copyright
notice and this notice must be preserved on all copies.

In other words, go ahead and share GDB, but don't try to stop
anyone else from sharing it farther.  Help stamp out software hoarding!
*/

#include "defs.h"
#include "initialize.h"
#include "param.h"
#include "symtab.h"
#include "frame.h"
#include "value.h"

CORE_ADDR read_register ();

START_FILE

/* Return the address in which frame FRAME's value of register REGNUM
   has been saved in memory.  Or return zero if it has not been saved.
   If REGNUM specifies the SP, the value we return is actually
   the SP value, not an address where it was saved.  */

static CORE_ADDR
find_saved_register (frame, regnum)
     FRAME frame;
     int regnum;
{
  struct frame_info fi;
  struct frame_saved_regs saved_regs;

  register FRAME frame1 = 0;
  register CORE_ADDR addr = 0;

  while (1)
    {
      QUIT;
      fi = get_prev_frame_info (frame1);
      if (fi.frame == 0 || fi.frame == frame)
	break;
      get_frame_saved_regs (&fi, &saved_regs);
      if (saved_regs.regs[regnum])
	addr = saved_regs.regs[regnum];
      frame1 = fi.frame;
    }

  return addr;
}

/* Copy the bytes of register REGNUM, relative to the current stack frame,
   into our memory at MYADDR.
   The number of bytes copied is REGISTER_RAW_SIZE (REGNUM).  */

void
read_relative_register_raw_bytes (regnum, myaddr)
     int regnum;
     char *myaddr;
{
  register CORE_ADDR addr;

  if (regnum == FP_REGNUM)
    {
      bcopy (&selected_frame, myaddr, sizeof (CORE_ADDR));
      return;
    }

  addr = find_saved_register (selected_frame, regnum);

  if (addr)
    {
      if (regnum == SP_REGNUM)
	{
	  CORE_ADDR buffer = addr;
	  bcopy (&buffer, myaddr, sizeof (CORE_ADDR));
	}
      else
	read_memory (addr, myaddr, REGISTER_RAW_SIZE (regnum));
      return;
    }
  read_register_bytes (REGISTER_BYTE (regnum),
		       myaddr, REGISTER_RAW_SIZE (regnum));
}

/* Return a `value' with the contents of register REGNUM
   in its virtual format, with the type specified by
   REGISTER_VIRTUAL_TYPE.  */

value
value_of_register (regnum)
     int regnum;
{
  register CORE_ADDR addr = find_saved_register (selected_frame, regnum);
  register value val;
  char raw_buffer[MAX_REGISTER_RAW_SIZE];
  char virtual_buffer[MAX_REGISTER_VIRTUAL_SIZE];

  if (addr)
    {
      if (regnum == SP_REGNUM)
	return value_from_long (builtin_type_int, addr);
      read_memory (addr, raw_buffer, REGISTER_RAW_SIZE (regnum));
    }
  else
    read_register_bytes (REGISTER_BYTE (regnum), raw_buffer,
			 REGISTER_RAW_SIZE (regnum));

  REGISTER_CONVERT_TO_VIRTUAL (regnum, raw_buffer, virtual_buffer);
  val = allocate_value (REGISTER_VIRTUAL_TYPE (regnum));
  bcopy (virtual_buffer, VALUE_CONTENTS (val), REGISTER_VIRTUAL_SIZE (regnum));
  VALUE_LVAL (val) = addr ? lval_memory : lval_register;
  VALUE_ADDRESS (val) = addr ? addr : REGISTER_BYTE (regnum);
  VALUE_REGNO (val) = regnum;
  return val;
}

/* Low level examining and depositing of registers.

   Note that you must call `fetch_registers' once
   before examining or depositing any registers.  */

char registers[REGISTER_BYTES];

/* Copy LEN bytes of consecutive data from registers
   starting with the REGBYTE'th byte of register data
   into memory at MYADDR.  */

read_register_bytes (regbyte, myaddr, len)
     int regbyte;
     char *myaddr;
     int len;
{
  bcopy (&registers[regbyte], myaddr, len);
}

/* Copy LEN bytes of consecutive data from memory at MYADDR
   into registers starting with the REGBYTE'th byte of register data.  */

write_register_bytes (regbyte, myaddr, len)
     int regbyte;
     char *myaddr;
     int len;
{
  bcopy (myaddr, &registers[regbyte], len);
  if (have_inferior_p ())
    store_inferior_registers (-1);
}

/* Return the contents of register REGNO,
   regarding it as an integer.  */

CORE_ADDR
read_register (regno)
     int regno;
{
  /* This loses when REGISTER_RAW_SIZE (regno) != sizeof (int) */
  return *(int *) &registers[REGISTER_BYTE (regno)];
}

/* Store VALUE in the register number REGNO, regarded as an integer.  */

void
write_register (regno, val)
     int regno, val;
{
  /* This loses when REGISTER_RAW_SIZE (regno) != sizeof (int) */
  *(int *) &registers[REGISTER_BYTE (regno)] = val;

  if (have_inferior_p ())
    store_inferior_registers (regno);
}

/* Record that register REGNO contains VAL.
   This is used when the value is obtained from the inferior or core dump,
   so there is no need to store the value there.  */

void
supply_register (regno, val)
     int regno;
     char *val;
{
  bcopy (val, &registers[REGISTER_BYTE (regno)], REGISTER_RAW_SIZE (regno));
}

/* Given a struct symbol for a variable,
   and a stack frame address, read the value of the variable
   and return a (pointer to a) struct value containing the value.  */

value
read_var_value (var, frame)
     register struct symbol *var;
     FRAME frame;
{
  register value v;

  struct frame_info fi;

  struct type *type = SYMBOL_TYPE (var);
  register CORE_ADDR addr = 0;
  int val = SYMBOL_VALUE (var);
  register int len;

  if (SYMBOL_CLASS (var) == LOC_BLOCK)
    type = lookup_function_type (type, 0);

  v = allocate_value (type);
  VALUE_LVAL (v) = lval_memory;	/* The most likely possibility.  */
  len = TYPE_LENGTH (type);

  if (frame == 0) frame = selected_frame;

  switch (SYMBOL_CLASS (var))
    {
    case LOC_CONST:
    case LOC_LABEL:
      bcopy (&val, VALUE_CONTENTS (v), len);
      VALUE_LVAL (v) = not_lval;
      return v;

    case LOC_CONST_BYTES:
      bcopy (val, VALUE_CONTENTS (v), len);
      VALUE_LVAL (v) = not_lval;
      return v;

    case LOC_STATIC:
      addr = val;
      break;

    case LOC_ARG:
      fi = get_frame_info (frame);
      addr = val + FRAME_ARGS_ADDRESS (fi);
      break;

    case LOC_LOCAL:
      fi = get_frame_info (frame);
      addr = val + FRAME_LOCALS_ADDRESS (fi);
      break;

    case LOC_TYPEDEF:
      error ("Cannot look up value of a typedef");

    case LOC_BLOCK:
      VALUE_ADDRESS (v) = BLOCK_START (SYMBOL_BLOCK_VALUE (var));
      return v;

    case LOC_REGISTER:
      {
	char raw_buffer[MAX_REGISTER_RAW_SIZE];
	char virtual_buffer[MAX_REGISTER_VIRTUAL_SIZE];

	VALUE_REGNO (v) = val;

	/* Locate the register's contents in a real register or in core;
	   read the data in raw format.  */

	addr = find_saved_register (frame, val);
	if (addr == 0)
	  {
	    /* Value is really in a register.  */

	    VALUE_LVAL (v) = lval_register;
	    VALUE_ADDRESS (v) = REGISTER_BYTE (val);

	    read_register_bytes (REGISTER_BYTE (val),
				 raw_buffer, REGISTER_RAW_SIZE (val));
	  }
	else
	  {
	    /* Value was in a register that has been saved in memory.  */

	    read_memory (addr, raw_buffer, REGISTER_RAW_SIZE (val));
	    VALUE_ADDRESS (v) = addr;
	  }

	/* Convert the raw contents to virtual contents.
	   (Just copy them if the formats are the same.)  */

	REGISTER_CONVERT_TO_VIRTUAL (val, raw_buffer, virtual_buffer);

	if (REGISTER_CONVERTIBLE (val))
	  {
	    /* When the raw and virtual formats differ, the virtual format
	       corresponds to a specific data type.  If we want that type,
	       copy the data into the value.
	       Otherwise, do a type-conversion.  */

	    if (type != REGISTER_VIRTUAL_TYPE (val))
	      {
		/* eg a variable of type `float' in a 68881 register
		   with raw type `extended' and virtual type `double'.
		   Fetch it as a `double' and then convert to `float'.  */
		v = allocate_value (REGISTER_VIRTUAL_TYPE (val));
		bcopy (virtual_buffer, VALUE_CONTENTS (v), len);
		v = value_cast (type, v);
	      }
	    else
	      bcopy (virtual_buffer, VALUE_CONTENTS (v), len);
	  }
	else
	  {
	    /* Raw and virtual formats are the same for this register.  */

	    union { int i; char c; } test;
	    /* If we want less than the full size, we need to
	       test for a big-endian or little-endian machine.  */
	    test.i = 1;
	    if (test.c != 1 && len < REGISTER_RAW_SIZE (val))
	      {
		/* Big-endian, and we want less than full size.  */
		VALUE_OFFSET (v) = REGISTER_RAW_SIZE (val) - len;
	      }

	    bcopy (virtual_buffer + VALUE_OFFSET (v),
		   VALUE_CONTENTS (v), len);
	  }

	return v;
      }
    }

  read_memory (addr, VALUE_CONTENTS (v), len);
  VALUE_ADDRESS (v) = addr;
  return v;
}

/* Given a struct symbol for a variable,
   and a stack frame address,
   return a (pointer to a) struct value containing the variable's address.  */

value
locate_var_value (var, frame)
     register struct symbol *var;
     FRAME frame;
{
  register CORE_ADDR addr = 0;
  int val = SYMBOL_VALUE (var);
  struct frame_info fi;

  if (frame == 0) frame = selected_frame;

  switch (SYMBOL_CLASS (var))
    {
    case LOC_CONST:
    case LOC_CONST_BYTES:
      error ("Address requested for identifier \"%s\" which is a constant.",
	     SYMBOL_NAME (var));

    case LOC_REGISTER:
      addr = find_saved_register (frame, val);
      if (addr != 0)
	{
	  union { int i; char c; } test;
	  int len = TYPE_LENGTH (SYMBOL_TYPE (var));
	  /* If var is less than the full size of register, we need to
	     test for a big-endian or little-endian machine.  */
	  test.i = 1;
	  if (test.c != 1 && len < REGISTER_RAW_SIZE (val))
	    /* Big-endian, and we want less than full size.  */
	    addr += REGISTER_RAW_SIZE (val) - len;
	  break;
	}
      error ("Address requested for identifier \"%s\" which is in a register.",
	     SYMBOL_NAME (var));

    case LOC_STATIC:
    case LOC_LABEL:
      addr = val;
      break;

    case LOC_ARG:
      fi = get_frame_info (frame);
      addr = val + FRAME_ARGS_ADDRESS (fi);
      break;

    case LOC_LOCAL:
      fi = get_frame_info (frame);
      addr = val + FRAME_LOCALS_ADDRESS (fi);
      break;

    case LOC_TYPEDEF:
      error ("Address requested for identifier \"%s\" which is a typedef.",
	     SYMBOL_NAME (var));

    case LOC_BLOCK:
      addr = BLOCK_START (SYMBOL_BLOCK_VALUE (var));
      break;
    }

  return value_cast (lookup_pointer_type (SYMBOL_TYPE (var)),
		     value_from_long (builtin_type_long, addr));
}

static
initialize ()
{}

END_FILE