1 /* Find a variable's value in memory, for GDB, the GNU debugger.
3 Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995,
4 1996, 1997, 1998, 1999, 2000, 2001, 2003, 2004, 2005, 2007, 2008, 2009,
5 2010 Free Software Foundation, Inc.
7 This file is part of GDB.
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.
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.
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/>. */
30 #include "gdb_string.h"
31 #include "gdb_assert.h"
32 #include "floatformat.h"
33 #include "symfile.h" /* for overlay functions */
35 #include "user-regs.h"
39 /* Basic byte-swapping routines. All 'extract' functions return a
40 host-format integer from a target-format integer at ADDR which is
43 #if TARGET_CHAR_BIT != 8 || HOST_CHAR_BIT != 8
44 /* 8 bit characters are a pretty safe assumption these days, so we
45 assume it throughout all these swapping routines. If we had to deal with
46 9 bit characters, we would need to make len be in bits and would have
47 to re-write these routines... */
52 extract_signed_integer (const gdb_byte
*addr
, int len
,
53 enum bfd_endian byte_order
)
56 const unsigned char *p
;
57 const unsigned char *startaddr
= addr
;
58 const unsigned char *endaddr
= startaddr
+ len
;
60 if (len
> (int) sizeof (LONGEST
))
62 That operation is not available on integers of more than %d bytes."),
63 (int) sizeof (LONGEST
));
65 /* Start at the most significant end of the integer, and work towards
66 the least significant. */
67 if (byte_order
== BFD_ENDIAN_BIG
)
70 /* Do the sign extension once at the start. */
71 retval
= ((LONGEST
) * p
^ 0x80) - 0x80;
72 for (++p
; p
< endaddr
; ++p
)
73 retval
= (retval
<< 8) | *p
;
78 /* Do the sign extension once at the start. */
79 retval
= ((LONGEST
) * p
^ 0x80) - 0x80;
80 for (--p
; p
>= startaddr
; --p
)
81 retval
= (retval
<< 8) | *p
;
87 extract_unsigned_integer (const gdb_byte
*addr
, int len
,
88 enum bfd_endian byte_order
)
91 const unsigned char *p
;
92 const unsigned char *startaddr
= addr
;
93 const unsigned char *endaddr
= startaddr
+ len
;
95 if (len
> (int) sizeof (ULONGEST
))
97 That operation is not available on integers of more than %d bytes."),
98 (int) sizeof (ULONGEST
));
100 /* Start at the most significant end of the integer, and work towards
101 the least significant. */
103 if (byte_order
== BFD_ENDIAN_BIG
)
105 for (p
= startaddr
; p
< endaddr
; ++p
)
106 retval
= (retval
<< 8) | *p
;
110 for (p
= endaddr
- 1; p
>= startaddr
; --p
)
111 retval
= (retval
<< 8) | *p
;
116 /* Sometimes a long long unsigned integer can be extracted as a
117 LONGEST value. This is done so that we can print these values
118 better. If this integer can be converted to a LONGEST, this
119 function returns 1 and sets *PVAL. Otherwise it returns 0. */
122 extract_long_unsigned_integer (const gdb_byte
*addr
, int orig_len
,
123 enum bfd_endian byte_order
, LONGEST
*pval
)
126 const gdb_byte
*first_addr
;
130 if (byte_order
== BFD_ENDIAN_BIG
)
133 len
> (int) sizeof (LONGEST
) && p
< addr
+ orig_len
;
146 for (p
= addr
+ orig_len
- 1;
147 len
> (int) sizeof (LONGEST
) && p
>= addr
;
157 if (len
<= (int) sizeof (LONGEST
))
159 *pval
= (LONGEST
) extract_unsigned_integer (first_addr
,
169 /* Treat the bytes at BUF as a pointer of type TYPE, and return the
170 address it represents. */
172 extract_typed_address (const gdb_byte
*buf
, struct type
*type
)
174 if (TYPE_CODE (type
) != TYPE_CODE_PTR
175 && TYPE_CODE (type
) != TYPE_CODE_REF
)
176 internal_error (__FILE__
, __LINE__
,
177 _("extract_typed_address: "
178 "type is not a pointer or reference"));
180 return gdbarch_pointer_to_address (get_type_arch (type
), type
, buf
);
183 /* All 'store' functions accept a host-format integer and store a
184 target-format integer at ADDR which is LEN bytes long. */
187 store_signed_integer (gdb_byte
*addr
, int len
,
188 enum bfd_endian byte_order
, LONGEST val
)
191 gdb_byte
*startaddr
= addr
;
192 gdb_byte
*endaddr
= startaddr
+ len
;
194 /* Start at the least significant end of the integer, and work towards
195 the most significant. */
196 if (byte_order
== BFD_ENDIAN_BIG
)
198 for (p
= endaddr
- 1; p
>= startaddr
; --p
)
206 for (p
= startaddr
; p
< endaddr
; ++p
)
215 store_unsigned_integer (gdb_byte
*addr
, int len
,
216 enum bfd_endian byte_order
, ULONGEST val
)
219 unsigned char *startaddr
= (unsigned char *) addr
;
220 unsigned char *endaddr
= startaddr
+ len
;
222 /* Start at the least significant end of the integer, and work towards
223 the most significant. */
224 if (byte_order
== BFD_ENDIAN_BIG
)
226 for (p
= endaddr
- 1; p
>= startaddr
; --p
)
234 for (p
= startaddr
; p
< endaddr
; ++p
)
242 /* Store the address ADDR as a pointer of type TYPE at BUF, in target
245 store_typed_address (gdb_byte
*buf
, struct type
*type
, CORE_ADDR addr
)
247 if (TYPE_CODE (type
) != TYPE_CODE_PTR
248 && TYPE_CODE (type
) != TYPE_CODE_REF
)
249 internal_error (__FILE__
, __LINE__
,
250 _("store_typed_address: "
251 "type is not a pointer or reference"));
253 gdbarch_address_to_pointer (get_type_arch (type
), type
, buf
, addr
);
258 /* Return a `value' with the contents of (virtual or cooked) register
259 REGNUM as found in the specified FRAME. The register's type is
260 determined by register_type(). */
263 value_of_register (int regnum
, struct frame_info
*frame
)
265 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
268 struct value
*reg_val
;
270 gdb_byte raw_buffer
[MAX_REGISTER_SIZE
];
273 /* User registers lie completely outside of the range of normal
274 registers. Catch them early so that the target never sees them. */
275 if (regnum
>= gdbarch_num_regs (gdbarch
)
276 + gdbarch_num_pseudo_regs (gdbarch
))
277 return value_of_user_reg (regnum
, frame
);
279 frame_register (frame
, regnum
, &optim
, &lval
, &addr
, &realnum
, raw_buffer
);
281 reg_val
= allocate_value (register_type (gdbarch
, regnum
));
283 memcpy (value_contents_raw (reg_val
), raw_buffer
,
284 register_size (gdbarch
, regnum
));
285 VALUE_LVAL (reg_val
) = lval
;
286 set_value_address (reg_val
, addr
);
287 VALUE_REGNUM (reg_val
) = regnum
;
288 set_value_optimized_out (reg_val
, optim
);
289 VALUE_FRAME_ID (reg_val
) = get_frame_id (frame
);
293 /* Return a `value' with the contents of (virtual or cooked) register
294 REGNUM as found in the specified FRAME. The register's type is
295 determined by register_type(). The value is not fetched. */
298 value_of_register_lazy (struct frame_info
*frame
, int regnum
)
300 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
301 struct value
*reg_val
;
303 gdb_assert (regnum
< (gdbarch_num_regs (gdbarch
)
304 + gdbarch_num_pseudo_regs (gdbarch
)));
306 /* We should have a valid (i.e. non-sentinel) frame. */
307 gdb_assert (frame_id_p (get_frame_id (frame
)));
309 reg_val
= allocate_value (register_type (gdbarch
, regnum
));
310 VALUE_LVAL (reg_val
) = lval_register
;
311 VALUE_REGNUM (reg_val
) = regnum
;
312 VALUE_FRAME_ID (reg_val
) = get_frame_id (frame
);
313 set_value_lazy (reg_val
, 1);
317 /* Given a pointer of type TYPE in target form in BUF, return the
318 address it represents. */
320 unsigned_pointer_to_address (struct gdbarch
*gdbarch
,
321 struct type
*type
, const gdb_byte
*buf
)
323 enum bfd_endian byte_order
= gdbarch_byte_order (gdbarch
);
325 return extract_unsigned_integer (buf
, TYPE_LENGTH (type
), byte_order
);
329 signed_pointer_to_address (struct gdbarch
*gdbarch
,
330 struct type
*type
, const gdb_byte
*buf
)
332 enum bfd_endian byte_order
= gdbarch_byte_order (gdbarch
);
334 return extract_signed_integer (buf
, TYPE_LENGTH (type
), byte_order
);
337 /* Given an address, store it as a pointer of type TYPE in target
340 unsigned_address_to_pointer (struct gdbarch
*gdbarch
, struct type
*type
,
341 gdb_byte
*buf
, CORE_ADDR addr
)
343 enum bfd_endian byte_order
= gdbarch_byte_order (gdbarch
);
345 store_unsigned_integer (buf
, TYPE_LENGTH (type
), byte_order
, addr
);
349 address_to_signed_pointer (struct gdbarch
*gdbarch
, struct type
*type
,
350 gdb_byte
*buf
, CORE_ADDR addr
)
352 enum bfd_endian byte_order
= gdbarch_byte_order (gdbarch
);
354 store_signed_integer (buf
, TYPE_LENGTH (type
), byte_order
, addr
);
357 /* Will calling read_var_value or locate_var_value on SYM end
358 up caring what frame it is being evaluated relative to? SYM must
361 symbol_read_needs_frame (struct symbol
*sym
)
363 switch (SYMBOL_CLASS (sym
))
365 /* All cases listed explicitly so that gcc -Wall will detect it if
366 we failed to consider one. */
368 /* FIXME: cagney/2004-01-26: It should be possible to
369 unconditionally call the SYMBOL_COMPUTED_OPS method when available.
370 Unfortunately DWARF 2 stores the frame-base (instead of the
371 function) location in a function's symbol. Oops! For the
372 moment enable this when/where applicable. */
373 return SYMBOL_COMPUTED_OPS (sym
)->read_needs_frame (sym
);
378 case LOC_REGPARM_ADDR
:
388 /* Getting the address of a label can be done independently of the block,
389 even if some *uses* of that address wouldn't work so well without
393 case LOC_CONST_BYTES
:
395 case LOC_OPTIMIZED_OUT
:
401 /* Given a struct symbol for a variable,
402 and a stack frame id, read the value of the variable
403 and return a (pointer to a) struct value containing the value.
404 If the variable cannot be found, return a zero pointer. */
407 read_var_value (struct symbol
*var
, struct frame_info
*frame
)
410 struct type
*type
= SYMBOL_TYPE (var
);
414 if (SYMBOL_CLASS (var
) == LOC_COMPUTED
415 || SYMBOL_CLASS (var
) == LOC_REGISTER
)
416 /* These cases do not use V. */
420 v
= allocate_value (type
);
421 VALUE_LVAL (v
) = lval_memory
; /* The most likely possibility. */
424 len
= TYPE_LENGTH (type
);
426 if (symbol_read_needs_frame (var
))
429 switch (SYMBOL_CLASS (var
))
432 /* Put the constant back in target format. */
433 store_signed_integer (value_contents_raw (v
), len
,
434 gdbarch_byte_order (get_type_arch (type
)),
435 (LONGEST
) SYMBOL_VALUE (var
));
436 VALUE_LVAL (v
) = not_lval
;
440 /* Put the constant back in target format. */
441 if (overlay_debugging
)
444 = symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var
),
445 SYMBOL_OBJ_SECTION (var
));
447 store_typed_address (value_contents_raw (v
), type
, addr
);
450 store_typed_address (value_contents_raw (v
), type
,
451 SYMBOL_VALUE_ADDRESS (var
));
452 VALUE_LVAL (v
) = not_lval
;
455 case LOC_CONST_BYTES
:
456 memcpy (value_contents_raw (v
), SYMBOL_VALUE_BYTES (var
), len
);
457 VALUE_LVAL (v
) = not_lval
;
461 if (overlay_debugging
)
462 addr
= symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var
),
463 SYMBOL_OBJ_SECTION (var
));
465 addr
= SYMBOL_VALUE_ADDRESS (var
);
469 addr
= get_frame_args_address (frame
);
472 addr
+= SYMBOL_VALUE (var
);
480 argref
= get_frame_args_address (frame
);
483 argref
+= SYMBOL_VALUE (var
);
484 ref
= value_at (lookup_pointer_type (type
), argref
);
485 addr
= value_as_address (ref
);
490 addr
= get_frame_locals_address (frame
);
491 addr
+= SYMBOL_VALUE (var
);
495 error (_("Cannot look up value of a typedef"));
499 if (overlay_debugging
)
500 set_value_address (v
, symbol_overlayed_address
501 (BLOCK_START (SYMBOL_BLOCK_VALUE (var
)), SYMBOL_OBJ_SECTION (var
)));
503 set_value_address (v
, BLOCK_START (SYMBOL_BLOCK_VALUE (var
)));
507 case LOC_REGPARM_ADDR
:
509 int regno
= SYMBOL_REGISTER_OPS (var
)
510 ->register_number (var
, get_frame_arch (frame
));
511 struct value
*regval
;
513 if (SYMBOL_CLASS (var
) == LOC_REGPARM_ADDR
)
515 regval
= value_from_register (lookup_pointer_type (type
),
520 error (_("Value of register variable not available."));
522 addr
= value_as_address (regval
);
523 VALUE_LVAL (v
) = lval_memory
;
527 regval
= value_from_register (type
, regno
, frame
);
530 error (_("Value of register variable not available."));
537 /* FIXME: cagney/2004-01-26: It should be possible to
538 unconditionally call the SYMBOL_COMPUTED_OPS method when available.
539 Unfortunately DWARF 2 stores the frame-base (instead of the
540 function) location in a function's symbol. Oops! For the
541 moment enable this when/where applicable. */
542 return SYMBOL_COMPUTED_OPS (var
)->read_variable (var
, frame
);
546 struct minimal_symbol
*msym
;
547 struct obj_section
*obj_section
;
549 msym
= lookup_minimal_symbol (SYMBOL_LINKAGE_NAME (var
), NULL
, NULL
);
552 if (overlay_debugging
)
553 addr
= symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (msym
),
554 SYMBOL_OBJ_SECTION (msym
));
556 addr
= SYMBOL_VALUE_ADDRESS (msym
);
558 obj_section
= SYMBOL_OBJ_SECTION (msym
);
560 && (obj_section
->the_bfd_section
->flags
& SEC_THREAD_LOCAL
) != 0)
561 addr
= target_translate_tls_address (obj_section
->objfile
, addr
);
565 case LOC_OPTIMIZED_OUT
:
566 VALUE_LVAL (v
) = not_lval
;
567 set_value_optimized_out (v
, 1);
571 error (_("Cannot look up value of a botched symbol."));
575 set_value_address (v
, addr
);
576 set_value_lazy (v
, 1);
580 /* Install default attributes for register values. */
583 default_value_from_register (struct type
*type
, int regnum
,
584 struct frame_info
*frame
)
586 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
587 int len
= TYPE_LENGTH (type
);
588 struct value
*value
= allocate_value (type
);
590 VALUE_LVAL (value
) = lval_register
;
591 VALUE_FRAME_ID (value
) = get_frame_id (frame
);
592 VALUE_REGNUM (value
) = regnum
;
594 /* Any structure stored in more than one register will always be
595 an integral number of registers. Otherwise, you need to do
596 some fiddling with the last register copied here for little
598 if (gdbarch_byte_order (gdbarch
) == BFD_ENDIAN_BIG
599 && len
< register_size (gdbarch
, regnum
))
600 /* Big-endian, and we want less than full size. */
601 set_value_offset (value
, register_size (gdbarch
, regnum
) - len
);
603 set_value_offset (value
, 0);
608 /* Return a value of type TYPE, stored in register REGNUM, in frame FRAME. */
611 value_from_register (struct type
*type
, int regnum
, struct frame_info
*frame
)
613 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
614 struct type
*type1
= check_typedef (type
);
617 if (gdbarch_convert_register_p (gdbarch
, regnum
, type1
))
619 /* The ISA/ABI need to something weird when obtaining the
620 specified value from this register. It might need to
621 re-order non-adjacent, starting with REGNUM (see MIPS and
622 i386). It might need to convert the [float] register into
623 the corresponding [integer] type (see Alpha). The assumption
624 is that gdbarch_register_to_value populates the entire value
625 including the location. */
626 v
= allocate_value (type
);
627 VALUE_LVAL (v
) = lval_register
;
628 VALUE_FRAME_ID (v
) = get_frame_id (frame
);
629 VALUE_REGNUM (v
) = regnum
;
630 gdbarch_register_to_value (gdbarch
,
631 frame
, regnum
, type1
, value_contents_raw (v
));
635 int len
= TYPE_LENGTH (type
);
637 /* Construct the value. */
638 v
= gdbarch_value_from_register (gdbarch
, type
, regnum
, frame
);
641 if (!get_frame_register_bytes (frame
, regnum
, value_offset (v
), len
,
642 value_contents_raw (v
)))
643 set_value_optimized_out (v
, 1);
648 /* Return contents of register REGNUM in frame FRAME as address,
649 interpreted as value of type TYPE. Will abort if register
650 value is not available. */
653 address_from_register (struct type
*type
, int regnum
, struct frame_info
*frame
)
658 value
= value_from_register (type
, regnum
, frame
);
661 result
= value_as_address (value
);
662 release_value (value
);
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