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
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 2 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, write to the Free Software
21 Foundation, Inc., 51 Franklin Street, Fifth Floor,
22 Boston, MA 02110-1301, USA. */
32 #include "gdb_string.h"
33 #include "gdb_assert.h"
34 #include "floatformat.h"
35 #include "symfile.h" /* for overlay functions */
37 #include "user-regs.h"
40 /* Basic byte-swapping routines. GDB has needed these for a long time...
41 All extract a target-format integer at ADDR which is LEN bytes long. */
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
)
55 const unsigned char *p
;
56 const unsigned char *startaddr
= addr
;
57 const unsigned char *endaddr
= startaddr
+ len
;
59 if (len
> (int) sizeof (LONGEST
))
61 That operation is not available on integers of more than %d bytes."),
62 (int) sizeof (LONGEST
));
64 /* Start at the most significant end of the integer, and work towards
65 the least significant. */
66 if (gdbarch_byte_order (current_gdbarch
) == BFD_ENDIAN_BIG
)
69 /* Do the sign extension once at the start. */
70 retval
= ((LONGEST
) * p
^ 0x80) - 0x80;
71 for (++p
; p
< endaddr
; ++p
)
72 retval
= (retval
<< 8) | *p
;
77 /* Do the sign extension once at the start. */
78 retval
= ((LONGEST
) * p
^ 0x80) - 0x80;
79 for (--p
; p
>= startaddr
; --p
)
80 retval
= (retval
<< 8) | *p
;
86 extract_unsigned_integer (const gdb_byte
*addr
, int len
)
89 const unsigned char *p
;
90 const unsigned char *startaddr
= addr
;
91 const unsigned char *endaddr
= startaddr
+ len
;
93 if (len
> (int) sizeof (ULONGEST
))
95 That operation is not available on integers of more than %d bytes."),
96 (int) sizeof (ULONGEST
));
98 /* Start at the most significant end of the integer, and work towards
99 the least significant. */
101 if (gdbarch_byte_order (current_gdbarch
) == BFD_ENDIAN_BIG
)
103 for (p
= startaddr
; p
< endaddr
; ++p
)
104 retval
= (retval
<< 8) | *p
;
108 for (p
= endaddr
- 1; p
>= startaddr
; --p
)
109 retval
= (retval
<< 8) | *p
;
114 /* Sometimes a long long unsigned integer can be extracted as a
115 LONGEST value. This is done so that we can print these values
116 better. If this integer can be converted to a LONGEST, this
117 function returns 1 and sets *PVAL. Otherwise it returns 0. */
120 extract_long_unsigned_integer (const gdb_byte
*addr
, int orig_len
,
124 const gdb_byte
*first_addr
;
128 if (gdbarch_byte_order (current_gdbarch
) == BFD_ENDIAN_BIG
)
131 len
> (int) sizeof (LONGEST
) && p
< addr
+ orig_len
;
144 for (p
= addr
+ orig_len
- 1;
145 len
> (int) sizeof (LONGEST
) && p
>= addr
;
155 if (len
<= (int) sizeof (LONGEST
))
157 *pval
= (LONGEST
) extract_unsigned_integer (first_addr
,
166 /* Treat the bytes at BUF as a pointer of type TYPE, and return the
167 address it represents. */
169 extract_typed_address (const gdb_byte
*buf
, struct type
*type
)
171 if (TYPE_CODE (type
) != TYPE_CODE_PTR
172 && TYPE_CODE (type
) != TYPE_CODE_REF
)
173 internal_error (__FILE__
, __LINE__
,
174 _("extract_typed_address: "
175 "type is not a pointer or reference"));
177 return POINTER_TO_ADDRESS (type
, buf
);
182 store_signed_integer (gdb_byte
*addr
, int len
, LONGEST val
)
185 gdb_byte
*startaddr
= addr
;
186 gdb_byte
*endaddr
= startaddr
+ len
;
188 /* Start at the least significant end of the integer, and work towards
189 the most significant. */
190 if (gdbarch_byte_order (current_gdbarch
) == BFD_ENDIAN_BIG
)
192 for (p
= endaddr
- 1; p
>= startaddr
; --p
)
200 for (p
= startaddr
; p
< endaddr
; ++p
)
209 store_unsigned_integer (gdb_byte
*addr
, int len
, ULONGEST val
)
212 unsigned char *startaddr
= (unsigned char *) addr
;
213 unsigned char *endaddr
= startaddr
+ len
;
215 /* Start at the least significant end of the integer, and work towards
216 the most significant. */
217 if (gdbarch_byte_order (current_gdbarch
) == BFD_ENDIAN_BIG
)
219 for (p
= endaddr
- 1; p
>= startaddr
; --p
)
227 for (p
= startaddr
; p
< endaddr
; ++p
)
235 /* Store the address ADDR as a pointer of type TYPE at BUF, in target
238 store_typed_address (gdb_byte
*buf
, struct type
*type
, CORE_ADDR addr
)
240 if (TYPE_CODE (type
) != TYPE_CODE_PTR
241 && TYPE_CODE (type
) != TYPE_CODE_REF
)
242 internal_error (__FILE__
, __LINE__
,
243 _("store_typed_address: "
244 "type is not a pointer or reference"));
246 ADDRESS_TO_POINTER (type
, buf
, addr
);
251 /* Return a `value' with the contents of (virtual or cooked) register
252 REGNUM as found in the specified FRAME. The register's type is
253 determined by register_type(). */
256 value_of_register (int regnum
, struct frame_info
*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 (current_gdbarch
)
268 + gdbarch_num_pseudo_regs (current_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 (current_gdbarch
, regnum
));
275 memcpy (value_contents_raw (reg_val
), raw_buffer
,
276 register_size (current_gdbarch
, regnum
));
277 VALUE_LVAL (reg_val
) = lval
;
278 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 /* Given a pointer of type TYPE in target form in BUF, return the
286 address it represents. */
288 unsigned_pointer_to_address (struct type
*type
, const gdb_byte
*buf
)
290 return extract_unsigned_integer (buf
, TYPE_LENGTH (type
));
294 signed_pointer_to_address (struct type
*type
, const gdb_byte
*buf
)
296 return extract_signed_integer (buf
, TYPE_LENGTH (type
));
299 /* Given an address, store it as a pointer of type TYPE in target
302 unsigned_address_to_pointer (struct type
*type
, gdb_byte
*buf
,
305 store_unsigned_integer (buf
, TYPE_LENGTH (type
), addr
);
309 address_to_signed_pointer (struct type
*type
, gdb_byte
*buf
, CORE_ADDR addr
)
311 store_signed_integer (buf
, TYPE_LENGTH (type
), addr
);
314 /* Will calling read_var_value or locate_var_value on SYM end
315 up caring what frame it is being evaluated relative to? SYM must
318 symbol_read_needs_frame (struct symbol
*sym
)
320 switch (SYMBOL_CLASS (sym
))
322 /* All cases listed explicitly so that gcc -Wall will detect it if
323 we failed to consider one. */
325 case LOC_COMPUTED_ARG
:
326 /* FIXME: cagney/2004-01-26: It should be possible to
327 unconditionally call the SYMBOL_OPS method when available.
328 Unfortunately DWARF 2 stores the frame-base (instead of the
329 function) location in a function's symbol. Oops! For the
330 moment enable this when/where applicable. */
331 return SYMBOL_OPS (sym
)->read_needs_frame (sym
);
337 case LOC_REGPARM_ADDR
:
341 case LOC_BASEREG_ARG
:
342 case LOC_HP_THREAD_LOCAL_STATIC
:
352 /* Getting the address of a label can be done independently of the block,
353 even if some *uses* of that address wouldn't work so well without
357 case LOC_CONST_BYTES
:
359 case LOC_OPTIMIZED_OUT
:
365 /* Given a struct symbol for a variable,
366 and a stack frame id, read the value of the variable
367 and return a (pointer to a) struct value containing the value.
368 If the variable cannot be found, return a zero pointer.
369 If FRAME is NULL, use the selected frame. */
372 read_var_value (struct symbol
*var
, struct frame_info
*frame
)
375 struct type
*type
= SYMBOL_TYPE (var
);
379 if (SYMBOL_CLASS (var
) == LOC_COMPUTED
380 || SYMBOL_CLASS (var
) == LOC_COMPUTED_ARG
381 || SYMBOL_CLASS (var
) == LOC_REGISTER
382 || SYMBOL_CLASS (var
) == LOC_REGPARM
)
383 /* These cases do not use V. */
387 v
= allocate_value (type
);
388 VALUE_LVAL (v
) = lval_memory
; /* The most likely possibility. */
391 len
= TYPE_LENGTH (type
);
393 /* FIXME drow/2003-09-06: this call to the selected frame should be
394 pushed upwards to the callers. */
396 frame
= deprecated_safe_get_selected_frame ();
398 switch (SYMBOL_CLASS (var
))
401 /* Put the constant back in target format. */
402 store_signed_integer (value_contents_raw (v
), len
,
403 (LONGEST
) SYMBOL_VALUE (var
));
404 VALUE_LVAL (v
) = not_lval
;
408 /* Put the constant back in target format. */
409 if (overlay_debugging
)
412 = symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var
),
413 SYMBOL_BFD_SECTION (var
));
414 store_typed_address (value_contents_raw (v
), type
, addr
);
417 store_typed_address (value_contents_raw (v
), type
,
418 SYMBOL_VALUE_ADDRESS (var
));
419 VALUE_LVAL (v
) = not_lval
;
422 case LOC_CONST_BYTES
:
424 memcpy (value_contents_raw (v
), SYMBOL_VALUE_BYTES (var
), len
);
425 VALUE_LVAL (v
) = not_lval
;
430 if (overlay_debugging
)
431 addr
= symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var
),
432 SYMBOL_BFD_SECTION (var
));
434 addr
= SYMBOL_VALUE_ADDRESS (var
);
439 /* The import slot does not have a real address in it from the
440 dynamic loader (dld.sl on HP-UX), if the target hasn't
441 begun execution yet, so check for that. */
444 if (!target_has_execution
)
446 Attempt to access variable defined in different shared object or load module when\n\
447 addresses have not been bound by the dynamic loader. Try again when executable is running."));
449 locaddr
= SYMBOL_VALUE_ADDRESS (var
);
450 loc
= value_at (lookup_pointer_type (type
), locaddr
);
451 addr
= value_as_address (loc
);
458 addr
= get_frame_args_address (frame
);
461 addr
+= SYMBOL_VALUE (var
);
470 argref
= get_frame_args_address (frame
);
473 argref
+= SYMBOL_VALUE (var
);
474 ref
= value_at (lookup_pointer_type (type
), argref
);
475 addr
= value_as_address (ref
);
483 addr
= get_frame_locals_address (frame
);
484 addr
+= SYMBOL_VALUE (var
);
488 case LOC_BASEREG_ARG
:
489 case LOC_HP_THREAD_LOCAL_STATIC
:
491 struct value
*regval
;
493 regval
= value_from_register (lookup_pointer_type (type
),
494 SYMBOL_BASEREG (var
), frame
);
496 error (_("Value of base register not available."));
497 addr
= value_as_address (regval
);
498 addr
+= SYMBOL_VALUE (var
);
503 error (_("Cannot look up value of a typedef"));
507 if (overlay_debugging
)
508 VALUE_ADDRESS (v
) = symbol_overlayed_address
509 (BLOCK_START (SYMBOL_BLOCK_VALUE (var
)), SYMBOL_BFD_SECTION (var
));
511 VALUE_ADDRESS (v
) = BLOCK_START (SYMBOL_BLOCK_VALUE (var
));
516 case LOC_REGPARM_ADDR
:
519 int regno
= SYMBOL_VALUE (var
);
520 struct value
*regval
;
524 b
= get_frame_block (frame
, 0);
526 if (SYMBOL_CLASS (var
) == LOC_REGPARM_ADDR
)
528 regval
= value_from_register (lookup_pointer_type (type
),
533 error (_("Value of register variable not available."));
535 addr
= value_as_address (regval
);
536 VALUE_LVAL (v
) = lval_memory
;
540 regval
= value_from_register (type
, regno
, frame
);
543 error (_("Value of register variable not available."));
550 case LOC_COMPUTED_ARG
:
551 /* FIXME: cagney/2004-01-26: It should be possible to
552 unconditionally call the SYMBOL_OPS method when available.
553 Unfortunately DWARF 2 stores the frame-base (instead of the
554 function) location in a function's symbol. Oops! For the
555 moment enable this when/where applicable. */
556 if (frame
== 0 && SYMBOL_OPS (var
)->read_needs_frame (var
))
558 return SYMBOL_OPS (var
)->read_variable (var
, frame
);
562 struct minimal_symbol
*msym
;
564 msym
= lookup_minimal_symbol (DEPRECATED_SYMBOL_NAME (var
), NULL
, NULL
);
567 if (overlay_debugging
)
568 addr
= symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (msym
),
569 SYMBOL_BFD_SECTION (msym
));
571 addr
= SYMBOL_VALUE_ADDRESS (msym
);
575 case LOC_OPTIMIZED_OUT
:
576 VALUE_LVAL (v
) = not_lval
;
577 set_value_optimized_out (v
, 1);
581 error (_("Cannot look up value of a botched symbol."));
585 VALUE_ADDRESS (v
) = addr
;
586 set_value_lazy (v
, 1);
590 /* Install default attributes for register values. */
593 default_value_from_register (struct type
*type
, int regnum
,
594 struct frame_info
*frame
)
596 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
597 int len
= TYPE_LENGTH (type
);
598 struct value
*value
= allocate_value (type
);
600 VALUE_LVAL (value
) = lval_register
;
601 VALUE_FRAME_ID (value
) = get_frame_id (frame
);
602 VALUE_REGNUM (value
) = regnum
;
604 /* Any structure stored in more than one register will always be
605 an integral number of registers. Otherwise, you need to do
606 some fiddling with the last register copied here for little
608 if (gdbarch_byte_order (current_gdbarch
) == BFD_ENDIAN_BIG
609 && len
< register_size (gdbarch
, regnum
))
610 /* Big-endian, and we want less than full size. */
611 set_value_offset (value
, register_size (gdbarch
, regnum
) - len
);
613 set_value_offset (value
, 0);
618 /* Return a value of type TYPE, stored in register REGNUM, in frame FRAME. */
621 value_from_register (struct type
*type
, int regnum
, struct frame_info
*frame
)
623 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
624 struct type
*type1
= check_typedef (type
);
627 if (CONVERT_REGISTER_P (regnum
, type1
))
629 /* The ISA/ABI need to something weird when obtaining the
630 specified value from this register. It might need to
631 re-order non-adjacent, starting with REGNUM (see MIPS and
632 i386). It might need to convert the [float] register into
633 the corresponding [integer] type (see Alpha). The assumption
634 is that REGISTER_TO_VALUE populates the entire value
635 including the location. */
636 v
= allocate_value (type
);
637 VALUE_LVAL (v
) = lval_register
;
638 VALUE_FRAME_ID (v
) = get_frame_id (frame
);
639 VALUE_REGNUM (v
) = regnum
;
640 REGISTER_TO_VALUE (frame
, regnum
, type1
, value_contents_raw (v
));
644 int len
= TYPE_LENGTH (type
);
646 /* Construct the value. */
647 v
= gdbarch_value_from_register (gdbarch
, type
, regnum
, frame
);
650 if (!get_frame_register_bytes (frame
, regnum
, value_offset (v
), len
,
651 value_contents_raw (v
)))
652 set_value_optimized_out (v
, 1);
657 /* Return contents of register REGNUM in frame FRAME as address,
658 interpreted as value of type TYPE. Will abort if register
659 value is not available. */
662 address_from_register (struct type
*type
, int regnum
, struct frame_info
*frame
)
667 value
= value_from_register (type
, regnum
, frame
);
670 result
= value_as_address (value
);
671 release_value (value
);
678 /* Given a struct symbol for a variable or function,
679 and a stack frame id,
680 return a (pointer to a) struct value containing the properly typed
684 locate_var_value (struct symbol
*var
, struct frame_info
*frame
)
687 struct type
*type
= SYMBOL_TYPE (var
);
688 struct value
*lazy_value
;
690 /* Evaluate it first; if the result is a memory address, we're fine.
691 Lazy evaluation pays off here. */
693 lazy_value
= read_var_value (var
, frame
);
695 error (_("Address of \"%s\" is unknown."), SYMBOL_PRINT_NAME (var
));
697 if (value_lazy (lazy_value
)
698 || TYPE_CODE (type
) == TYPE_CODE_FUNC
)
702 addr
= VALUE_ADDRESS (lazy_value
);
703 val
= value_from_pointer (lookup_pointer_type (type
), addr
);
707 /* Not a memory address; check what the problem was. */
708 switch (VALUE_LVAL (lazy_value
))
711 gdb_assert (REGISTER_NAME (VALUE_REGNUM (lazy_value
)) != NULL
712 && *REGISTER_NAME (VALUE_REGNUM (lazy_value
)) != '\0');
713 error (_("Address requested for identifier "
714 "\"%s\" which is in register $%s"),
715 SYMBOL_PRINT_NAME (var
),
716 REGISTER_NAME (VALUE_REGNUM (lazy_value
)));
720 error (_("Can't take address of \"%s\" which isn't an lvalue."),
721 SYMBOL_PRINT_NAME (var
));
724 return 0; /* For lint -- never reached */