4063bbe1903f0e7454d70d38bf297d47b24494bd
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 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. GDB has needed these for a long time...
40 All extract a target-format integer at ADDR which is LEN bytes long. */
42 #if TARGET_CHAR_BIT != 8 || HOST_CHAR_BIT != 8
43 /* 8 bit characters are a pretty safe assumption these days, so we
44 assume it throughout all these swapping routines. If we had to deal with
45 9 bit characters, we would need to make len be in bits and would have
46 to re-write these routines... */
51 extract_signed_integer (const gdb_byte
*addr
, int len
)
54 const unsigned char *p
;
55 const unsigned char *startaddr
= addr
;
56 const unsigned char *endaddr
= startaddr
+ len
;
58 if (len
> (int) sizeof (LONGEST
))
60 That operation is not available on integers of more than %d bytes."),
61 (int) sizeof (LONGEST
));
63 /* Start at the most significant end of the integer, and work towards
64 the least significant. */
65 if (gdbarch_byte_order (current_gdbarch
) == BFD_ENDIAN_BIG
)
68 /* Do the sign extension once at the start. */
69 retval
= ((LONGEST
) * p
^ 0x80) - 0x80;
70 for (++p
; p
< endaddr
; ++p
)
71 retval
= (retval
<< 8) | *p
;
76 /* Do the sign extension once at the start. */
77 retval
= ((LONGEST
) * p
^ 0x80) - 0x80;
78 for (--p
; p
>= startaddr
; --p
)
79 retval
= (retval
<< 8) | *p
;
85 extract_unsigned_integer (const gdb_byte
*addr
, int len
)
88 const unsigned char *p
;
89 const unsigned char *startaddr
= addr
;
90 const unsigned char *endaddr
= startaddr
+ len
;
92 if (len
> (int) sizeof (ULONGEST
))
94 That operation is not available on integers of more than %d bytes."),
95 (int) sizeof (ULONGEST
));
97 /* Start at the most significant end of the integer, and work towards
98 the least significant. */
100 if (gdbarch_byte_order (current_gdbarch
) == BFD_ENDIAN_BIG
)
102 for (p
= startaddr
; p
< endaddr
; ++p
)
103 retval
= (retval
<< 8) | *p
;
107 for (p
= endaddr
- 1; p
>= startaddr
; --p
)
108 retval
= (retval
<< 8) | *p
;
113 /* Sometimes a long long unsigned integer can be extracted as a
114 LONGEST value. This is done so that we can print these values
115 better. If this integer can be converted to a LONGEST, this
116 function returns 1 and sets *PVAL. Otherwise it returns 0. */
119 extract_long_unsigned_integer (const gdb_byte
*addr
, int orig_len
,
123 const gdb_byte
*first_addr
;
127 if (gdbarch_byte_order (current_gdbarch
) == BFD_ENDIAN_BIG
)
130 len
> (int) sizeof (LONGEST
) && p
< addr
+ orig_len
;
143 for (p
= addr
+ orig_len
- 1;
144 len
> (int) sizeof (LONGEST
) && p
>= addr
;
154 if (len
<= (int) sizeof (LONGEST
))
156 *pval
= (LONGEST
) extract_unsigned_integer (first_addr
,
165 /* Treat the bytes at BUF as a pointer of type TYPE, and return the
166 address it represents. */
168 extract_typed_address (const gdb_byte
*buf
, struct type
*type
)
170 if (TYPE_CODE (type
) != TYPE_CODE_PTR
171 && TYPE_CODE (type
) != TYPE_CODE_REF
)
172 internal_error (__FILE__
, __LINE__
,
173 _("extract_typed_address: "
174 "type is not a pointer or reference"));
176 return gdbarch_pointer_to_address (get_type_arch (type
), type
, buf
);
181 store_signed_integer (gdb_byte
*addr
, int len
, LONGEST val
)
184 gdb_byte
*startaddr
= addr
;
185 gdb_byte
*endaddr
= startaddr
+ len
;
187 /* Start at the least significant end of the integer, and work towards
188 the most significant. */
189 if (gdbarch_byte_order (current_gdbarch
) == BFD_ENDIAN_BIG
)
191 for (p
= endaddr
- 1; p
>= startaddr
; --p
)
199 for (p
= startaddr
; p
< endaddr
; ++p
)
208 store_unsigned_integer (gdb_byte
*addr
, int len
, ULONGEST val
)
211 unsigned char *startaddr
= (unsigned char *) addr
;
212 unsigned char *endaddr
= startaddr
+ len
;
214 /* Start at the least significant end of the integer, and work towards
215 the most significant. */
216 if (gdbarch_byte_order (current_gdbarch
) == BFD_ENDIAN_BIG
)
218 for (p
= endaddr
- 1; p
>= startaddr
; --p
)
226 for (p
= startaddr
; p
< endaddr
; ++p
)
234 /* Store the address ADDR as a pointer of type TYPE at BUF, in target
237 store_typed_address (gdb_byte
*buf
, struct type
*type
, CORE_ADDR addr
)
239 if (TYPE_CODE (type
) != TYPE_CODE_PTR
240 && TYPE_CODE (type
) != TYPE_CODE_REF
)
241 internal_error (__FILE__
, __LINE__
,
242 _("store_typed_address: "
243 "type is not a pointer or reference"));
245 gdbarch_address_to_pointer (get_type_arch (type
), type
, buf
, addr
);
250 /* Return a `value' with the contents of (virtual or cooked) register
251 REGNUM as found in the specified FRAME. The register's type is
252 determined by register_type(). */
255 value_of_register (int regnum
, struct frame_info
*frame
)
257 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
260 struct value
*reg_val
;
262 gdb_byte raw_buffer
[MAX_REGISTER_SIZE
];
265 /* User registers lie completely outside of the range of normal
266 registers. Catch them early so that the target never sees them. */
267 if (regnum
>= gdbarch_num_regs (gdbarch
)
268 + gdbarch_num_pseudo_regs (gdbarch
))
269 return value_of_user_reg (regnum
, frame
);
271 frame_register (frame
, regnum
, &optim
, &lval
, &addr
, &realnum
, raw_buffer
);
273 reg_val
= allocate_value (register_type (gdbarch
, regnum
));
275 memcpy (value_contents_raw (reg_val
), raw_buffer
,
276 register_size (gdbarch
, regnum
));
277 VALUE_LVAL (reg_val
) = lval
;
278 set_value_address (reg_val
, addr
);
279 VALUE_REGNUM (reg_val
) = regnum
;
280 set_value_optimized_out (reg_val
, optim
);
281 VALUE_FRAME_ID (reg_val
) = get_frame_id (frame
);
285 /* Return a `value' with the contents of (virtual or cooked) register
286 REGNUM as found in the specified FRAME. The register's type is
287 determined by register_type(). The value is not fetched. */
290 value_of_register_lazy (struct frame_info
*frame
, int regnum
)
292 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
293 struct value
*reg_val
;
295 gdb_assert (regnum
< (gdbarch_num_regs (gdbarch
)
296 + gdbarch_num_pseudo_regs (gdbarch
)));
298 /* We should have a valid (i.e. non-sentinel) frame. */
299 gdb_assert (frame_id_p (get_frame_id (frame
)));
301 reg_val
= allocate_value (register_type (gdbarch
, regnum
));
302 VALUE_LVAL (reg_val
) = lval_register
;
303 VALUE_REGNUM (reg_val
) = regnum
;
304 VALUE_FRAME_ID (reg_val
) = get_frame_id (frame
);
305 set_value_lazy (reg_val
, 1);
309 /* Given a pointer of type TYPE in target form in BUF, return the
310 address it represents. */
312 unsigned_pointer_to_address (struct gdbarch
*gdbarch
,
313 struct type
*type
, const gdb_byte
*buf
)
315 return extract_unsigned_integer (buf
, TYPE_LENGTH (type
));
319 signed_pointer_to_address (struct gdbarch
*gdbarch
,
320 struct type
*type
, const gdb_byte
*buf
)
322 return extract_signed_integer (buf
, TYPE_LENGTH (type
));
325 /* Given an address, store it as a pointer of type TYPE in target
328 unsigned_address_to_pointer (struct gdbarch
*gdbarch
, struct type
*type
,
329 gdb_byte
*buf
, CORE_ADDR addr
)
331 store_unsigned_integer (buf
, TYPE_LENGTH (type
), addr
);
335 address_to_signed_pointer (struct gdbarch
*gdbarch
, struct type
*type
,
336 gdb_byte
*buf
, CORE_ADDR addr
)
338 store_signed_integer (buf
, TYPE_LENGTH (type
), addr
);
341 /* Will calling read_var_value or locate_var_value on SYM end
342 up caring what frame it is being evaluated relative to? SYM must
345 symbol_read_needs_frame (struct symbol
*sym
)
347 switch (SYMBOL_CLASS (sym
))
349 /* All cases listed explicitly so that gcc -Wall will detect it if
350 we failed to consider one. */
352 /* FIXME: cagney/2004-01-26: It should be possible to
353 unconditionally call the SYMBOL_COMPUTED_OPS method when available.
354 Unfortunately DWARF 2 stores the frame-base (instead of the
355 function) location in a function's symbol. Oops! For the
356 moment enable this when/where applicable. */
357 return SYMBOL_COMPUTED_OPS (sym
)->read_needs_frame (sym
);
362 case LOC_REGPARM_ADDR
:
372 /* Getting the address of a label can be done independently of the block,
373 even if some *uses* of that address wouldn't work so well without
377 case LOC_CONST_BYTES
:
379 case LOC_OPTIMIZED_OUT
:
385 /* Given a struct symbol for a variable,
386 and a stack frame id, read the value of the variable
387 and return a (pointer to a) struct value containing the value.
388 If the variable cannot be found, return a zero pointer. */
391 read_var_value (struct symbol
*var
, struct frame_info
*frame
)
394 struct type
*type
= SYMBOL_TYPE (var
);
398 if (SYMBOL_CLASS (var
) == LOC_COMPUTED
399 || SYMBOL_CLASS (var
) == LOC_REGISTER
)
400 /* These cases do not use V. */
404 v
= allocate_value (type
);
405 VALUE_LVAL (v
) = lval_memory
; /* The most likely possibility. */
408 len
= TYPE_LENGTH (type
);
410 if (symbol_read_needs_frame (var
))
413 switch (SYMBOL_CLASS (var
))
416 /* Put the constant back in target format. */
417 store_signed_integer (value_contents_raw (v
), len
,
418 (LONGEST
) SYMBOL_VALUE (var
));
419 VALUE_LVAL (v
) = not_lval
;
423 /* Put the constant back in target format. */
424 if (overlay_debugging
)
427 = symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var
),
428 SYMBOL_OBJ_SECTION (var
));
429 store_typed_address (value_contents_raw (v
), type
, addr
);
432 store_typed_address (value_contents_raw (v
), type
,
433 SYMBOL_VALUE_ADDRESS (var
));
434 VALUE_LVAL (v
) = not_lval
;
437 case LOC_CONST_BYTES
:
439 memcpy (value_contents_raw (v
), SYMBOL_VALUE_BYTES (var
), len
);
440 VALUE_LVAL (v
) = not_lval
;
445 if (overlay_debugging
)
446 addr
= symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var
),
447 SYMBOL_OBJ_SECTION (var
));
449 addr
= SYMBOL_VALUE_ADDRESS (var
);
453 addr
= get_frame_args_address (frame
);
456 addr
+= SYMBOL_VALUE (var
);
463 argref
= get_frame_args_address (frame
);
466 argref
+= SYMBOL_VALUE (var
);
467 ref
= value_at (lookup_pointer_type (type
), argref
);
468 addr
= value_as_address (ref
);
473 addr
= get_frame_locals_address (frame
);
474 addr
+= SYMBOL_VALUE (var
);
478 error (_("Cannot look up value of a typedef"));
482 if (overlay_debugging
)
483 set_value_address (v
, symbol_overlayed_address
484 (BLOCK_START (SYMBOL_BLOCK_VALUE (var
)), SYMBOL_OBJ_SECTION (var
)));
486 set_value_address (v
, BLOCK_START (SYMBOL_BLOCK_VALUE (var
)));
490 case LOC_REGPARM_ADDR
:
492 int regno
= SYMBOL_REGISTER_OPS (var
)
493 ->register_number (var
, get_frame_arch (frame
));
494 struct value
*regval
;
496 if (SYMBOL_CLASS (var
) == LOC_REGPARM_ADDR
)
498 regval
= value_from_register (lookup_pointer_type (type
),
503 error (_("Value of register variable not available."));
505 addr
= value_as_address (regval
);
506 VALUE_LVAL (v
) = lval_memory
;
510 regval
= value_from_register (type
, regno
, frame
);
513 error (_("Value of register variable not available."));
520 /* FIXME: cagney/2004-01-26: It should be possible to
521 unconditionally call the SYMBOL_COMPUTED_OPS method when available.
522 Unfortunately DWARF 2 stores the frame-base (instead of the
523 function) location in a function's symbol. Oops! For the
524 moment enable this when/where applicable. */
525 return SYMBOL_COMPUTED_OPS (var
)->read_variable (var
, frame
);
529 struct minimal_symbol
*msym
;
530 struct obj_section
*obj_section
;
532 msym
= lookup_minimal_symbol (SYMBOL_LINKAGE_NAME (var
), NULL
, NULL
);
535 if (overlay_debugging
)
536 addr
= symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (msym
),
537 SYMBOL_OBJ_SECTION (msym
));
539 addr
= SYMBOL_VALUE_ADDRESS (msym
);
541 obj_section
= SYMBOL_OBJ_SECTION (msym
);
543 && (obj_section
->the_bfd_section
->flags
& SEC_THREAD_LOCAL
) != 0)
544 addr
= target_translate_tls_address (obj_section
->objfile
, addr
);
548 case LOC_OPTIMIZED_OUT
:
549 VALUE_LVAL (v
) = not_lval
;
550 set_value_optimized_out (v
, 1);
554 error (_("Cannot look up value of a botched symbol."));
558 set_value_address (v
, addr
);
559 set_value_lazy (v
, 1);
563 /* Install default attributes for register values. */
566 default_value_from_register (struct type
*type
, int regnum
,
567 struct frame_info
*frame
)
569 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
570 int len
= TYPE_LENGTH (type
);
571 struct value
*value
= allocate_value (type
);
573 VALUE_LVAL (value
) = lval_register
;
574 VALUE_FRAME_ID (value
) = get_frame_id (frame
);
575 VALUE_REGNUM (value
) = regnum
;
577 /* Any structure stored in more than one register will always be
578 an integral number of registers. Otherwise, you need to do
579 some fiddling with the last register copied here for little
581 if (gdbarch_byte_order (gdbarch
) == BFD_ENDIAN_BIG
582 && len
< register_size (gdbarch
, regnum
))
583 /* Big-endian, and we want less than full size. */
584 set_value_offset (value
, register_size (gdbarch
, regnum
) - len
);
586 set_value_offset (value
, 0);
591 /* Return a value of type TYPE, stored in register REGNUM, in frame FRAME. */
594 value_from_register (struct type
*type
, int regnum
, struct frame_info
*frame
)
596 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
597 struct type
*type1
= check_typedef (type
);
600 if (gdbarch_convert_register_p (gdbarch
, regnum
, type1
))
602 /* The ISA/ABI need to something weird when obtaining the
603 specified value from this register. It might need to
604 re-order non-adjacent, starting with REGNUM (see MIPS and
605 i386). It might need to convert the [float] register into
606 the corresponding [integer] type (see Alpha). The assumption
607 is that gdbarch_register_to_value populates the entire value
608 including the location. */
609 v
= allocate_value (type
);
610 VALUE_LVAL (v
) = lval_register
;
611 VALUE_FRAME_ID (v
) = get_frame_id (frame
);
612 VALUE_REGNUM (v
) = regnum
;
613 gdbarch_register_to_value (gdbarch
,
614 frame
, regnum
, type1
, value_contents_raw (v
));
618 int len
= TYPE_LENGTH (type
);
620 /* Construct the value. */
621 v
= gdbarch_value_from_register (gdbarch
, type
, regnum
, frame
);
624 if (!get_frame_register_bytes (frame
, regnum
, value_offset (v
), len
,
625 value_contents_raw (v
)))
626 set_value_optimized_out (v
, 1);
631 /* Return contents of register REGNUM in frame FRAME as address,
632 interpreted as value of type TYPE. Will abort if register
633 value is not available. */
636 address_from_register (struct type
*type
, int regnum
, struct frame_info
*frame
)
641 value
= value_from_register (type
, regnum
, frame
);
644 result
= value_as_address (value
);
645 release_value (value
);
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