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
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"
38 /* Basic byte-swapping routines. GDB has needed these for a long time...
39 All extract a target-format integer at ADDR which is LEN bytes long. */
41 #if TARGET_CHAR_BIT != 8 || HOST_CHAR_BIT != 8
42 /* 8 bit characters are a pretty safe assumption these days, so we
43 assume it throughout all these swapping routines. If we had to deal with
44 9 bit characters, we would need to make len be in bits and would have
45 to re-write these routines... */
50 extract_signed_integer (const gdb_byte
*addr
, int len
)
53 const unsigned char *p
;
54 const unsigned char *startaddr
= addr
;
55 const unsigned char *endaddr
= startaddr
+ len
;
57 if (len
> (int) sizeof (LONGEST
))
59 That operation is not available on integers of more than %d bytes."),
60 (int) sizeof (LONGEST
));
62 /* Start at the most significant end of the integer, and work towards
63 the least significant. */
64 if (gdbarch_byte_order (current_gdbarch
) == BFD_ENDIAN_BIG
)
67 /* Do the sign extension once at the start. */
68 retval
= ((LONGEST
) * p
^ 0x80) - 0x80;
69 for (++p
; p
< endaddr
; ++p
)
70 retval
= (retval
<< 8) | *p
;
75 /* Do the sign extension once at the start. */
76 retval
= ((LONGEST
) * p
^ 0x80) - 0x80;
77 for (--p
; p
>= startaddr
; --p
)
78 retval
= (retval
<< 8) | *p
;
84 extract_unsigned_integer (const gdb_byte
*addr
, int len
)
87 const unsigned char *p
;
88 const unsigned char *startaddr
= addr
;
89 const unsigned char *endaddr
= startaddr
+ len
;
91 if (len
> (int) sizeof (ULONGEST
))
93 That operation is not available on integers of more than %d bytes."),
94 (int) sizeof (ULONGEST
));
96 /* Start at the most significant end of the integer, and work towards
97 the least significant. */
99 if (gdbarch_byte_order (current_gdbarch
) == BFD_ENDIAN_BIG
)
101 for (p
= startaddr
; p
< endaddr
; ++p
)
102 retval
= (retval
<< 8) | *p
;
106 for (p
= endaddr
- 1; p
>= startaddr
; --p
)
107 retval
= (retval
<< 8) | *p
;
112 /* Sometimes a long long unsigned integer can be extracted as a
113 LONGEST value. This is done so that we can print these values
114 better. If this integer can be converted to a LONGEST, this
115 function returns 1 and sets *PVAL. Otherwise it returns 0. */
118 extract_long_unsigned_integer (const gdb_byte
*addr
, int orig_len
,
122 const gdb_byte
*first_addr
;
126 if (gdbarch_byte_order (current_gdbarch
) == BFD_ENDIAN_BIG
)
129 len
> (int) sizeof (LONGEST
) && p
< addr
+ orig_len
;
142 for (p
= addr
+ orig_len
- 1;
143 len
> (int) sizeof (LONGEST
) && p
>= addr
;
153 if (len
<= (int) sizeof (LONGEST
))
155 *pval
= (LONGEST
) extract_unsigned_integer (first_addr
,
164 /* Treat the bytes at BUF as a pointer of type TYPE, and return the
165 address it represents. */
167 extract_typed_address (const gdb_byte
*buf
, struct type
*type
)
169 if (TYPE_CODE (type
) != TYPE_CODE_PTR
170 && TYPE_CODE (type
) != TYPE_CODE_REF
)
171 internal_error (__FILE__
, __LINE__
,
172 _("extract_typed_address: "
173 "type is not a pointer or reference"));
175 return gdbarch_pointer_to_address (current_gdbarch
, type
, buf
);
180 store_signed_integer (gdb_byte
*addr
, int len
, LONGEST val
)
183 gdb_byte
*startaddr
= addr
;
184 gdb_byte
*endaddr
= startaddr
+ len
;
186 /* Start at the least significant end of the integer, and work towards
187 the most significant. */
188 if (gdbarch_byte_order (current_gdbarch
) == BFD_ENDIAN_BIG
)
190 for (p
= endaddr
- 1; p
>= startaddr
; --p
)
198 for (p
= startaddr
; p
< endaddr
; ++p
)
207 store_unsigned_integer (gdb_byte
*addr
, int len
, ULONGEST val
)
210 unsigned char *startaddr
= (unsigned char *) addr
;
211 unsigned char *endaddr
= startaddr
+ len
;
213 /* Start at the least significant end of the integer, and work towards
214 the most significant. */
215 if (gdbarch_byte_order (current_gdbarch
) == BFD_ENDIAN_BIG
)
217 for (p
= endaddr
- 1; p
>= startaddr
; --p
)
225 for (p
= startaddr
; p
< endaddr
; ++p
)
233 /* Store the address ADDR as a pointer of type TYPE at BUF, in target
236 store_typed_address (gdb_byte
*buf
, struct type
*type
, CORE_ADDR addr
)
238 if (TYPE_CODE (type
) != TYPE_CODE_PTR
239 && TYPE_CODE (type
) != TYPE_CODE_REF
)
240 internal_error (__FILE__
, __LINE__
,
241 _("store_typed_address: "
242 "type is not a pointer or reference"));
244 gdbarch_address_to_pointer (current_gdbarch
, type
, buf
, addr
);
249 /* Return a `value' with the contents of (virtual or cooked) register
250 REGNUM as found in the specified FRAME. The register's type is
251 determined by register_type(). */
254 value_of_register (int regnum
, struct frame_info
*frame
)
256 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
259 struct value
*reg_val
;
261 gdb_byte raw_buffer
[MAX_REGISTER_SIZE
];
264 /* User registers lie completely outside of the range of normal
265 registers. Catch them early so that the target never sees them. */
266 if (regnum
>= gdbarch_num_regs (gdbarch
)
267 + gdbarch_num_pseudo_regs (gdbarch
))
268 return value_of_user_reg (regnum
, frame
);
270 frame_register (frame
, regnum
, &optim
, &lval
, &addr
, &realnum
, raw_buffer
);
272 reg_val
= allocate_value (register_type (gdbarch
, regnum
));
274 memcpy (value_contents_raw (reg_val
), raw_buffer
,
275 register_size (gdbarch
, regnum
));
276 VALUE_LVAL (reg_val
) = lval
;
277 VALUE_ADDRESS (reg_val
) = addr
;
278 VALUE_REGNUM (reg_val
) = regnum
;
279 set_value_optimized_out (reg_val
, optim
);
280 VALUE_FRAME_ID (reg_val
) = get_frame_id (frame
);
284 /* Return a `value' with the contents of (virtual or cooked) register
285 REGNUM as found in the specified FRAME. The register's type is
286 determined by register_type(). The value is not fetched. */
289 value_of_register_lazy (struct frame_info
*frame
, int regnum
)
291 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
292 struct value
*reg_val
;
294 gdb_assert (regnum
< (gdbarch_num_regs (gdbarch
)
295 + gdbarch_num_pseudo_regs (gdbarch
)));
297 /* We should have a valid (i.e. non-sentinel) frame. */
298 gdb_assert (frame_id_p (get_frame_id (frame
)));
300 reg_val
= allocate_value (register_type (gdbarch
, regnum
));
301 VALUE_LVAL (reg_val
) = lval_register
;
302 VALUE_REGNUM (reg_val
) = regnum
;
303 VALUE_FRAME_ID (reg_val
) = get_frame_id (frame
);
304 set_value_lazy (reg_val
, 1);
308 /* Given a pointer of type TYPE in target form in BUF, return the
309 address it represents. */
311 unsigned_pointer_to_address (struct type
*type
, const gdb_byte
*buf
)
313 return extract_unsigned_integer (buf
, TYPE_LENGTH (type
));
317 signed_pointer_to_address (struct type
*type
, const gdb_byte
*buf
)
319 return extract_signed_integer (buf
, TYPE_LENGTH (type
));
322 /* Given an address, store it as a pointer of type TYPE in target
325 unsigned_address_to_pointer (struct type
*type
, gdb_byte
*buf
,
328 store_unsigned_integer (buf
, TYPE_LENGTH (type
), addr
);
332 address_to_signed_pointer (struct type
*type
, gdb_byte
*buf
, CORE_ADDR addr
)
334 store_signed_integer (buf
, TYPE_LENGTH (type
), addr
);
337 /* Will calling read_var_value or locate_var_value on SYM end
338 up caring what frame it is being evaluated relative to? SYM must
341 symbol_read_needs_frame (struct symbol
*sym
)
343 switch (SYMBOL_CLASS (sym
))
345 /* All cases listed explicitly so that gcc -Wall will detect it if
346 we failed to consider one. */
348 case LOC_COMPUTED_ARG
:
349 /* FIXME: cagney/2004-01-26: It should be possible to
350 unconditionally call the SYMBOL_OPS method when available.
351 Unfortunately DWARF 2 stores the frame-base (instead of the
352 function) location in a function's symbol. Oops! For the
353 moment enable this when/where applicable. */
354 return SYMBOL_OPS (sym
)->read_needs_frame (sym
);
360 case LOC_REGPARM_ADDR
:
364 case LOC_BASEREG_ARG
:
365 case LOC_HP_THREAD_LOCAL_STATIC
:
375 /* Getting the address of a label can be done independently of the block,
376 even if some *uses* of that address wouldn't work so well without
380 case LOC_CONST_BYTES
:
382 case LOC_OPTIMIZED_OUT
:
388 /* Given a struct symbol for a variable,
389 and a stack frame id, read the value of the variable
390 and return a (pointer to a) struct value containing the value.
391 If the variable cannot be found, return a zero pointer.
392 If FRAME is NULL, use the selected frame. */
395 read_var_value (struct symbol
*var
, struct frame_info
*frame
)
398 struct type
*type
= SYMBOL_TYPE (var
);
402 if (SYMBOL_CLASS (var
) == LOC_COMPUTED
403 || SYMBOL_CLASS (var
) == LOC_COMPUTED_ARG
404 || SYMBOL_CLASS (var
) == LOC_REGISTER
405 || SYMBOL_CLASS (var
) == LOC_REGPARM
)
406 /* These cases do not use V. */
410 v
= allocate_value (type
);
411 VALUE_LVAL (v
) = lval_memory
; /* The most likely possibility. */
414 len
= TYPE_LENGTH (type
);
416 /* FIXME drow/2003-09-06: this call to the selected frame should be
417 pushed upwards to the callers. */
419 frame
= deprecated_safe_get_selected_frame ();
421 switch (SYMBOL_CLASS (var
))
424 /* Put the constant back in target format. */
425 store_signed_integer (value_contents_raw (v
), len
,
426 (LONGEST
) SYMBOL_VALUE (var
));
427 VALUE_LVAL (v
) = not_lval
;
431 /* Put the constant back in target format. */
432 if (overlay_debugging
)
435 = symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var
),
436 SYMBOL_BFD_SECTION (var
));
437 store_typed_address (value_contents_raw (v
), type
, addr
);
440 store_typed_address (value_contents_raw (v
), type
,
441 SYMBOL_VALUE_ADDRESS (var
));
442 VALUE_LVAL (v
) = not_lval
;
445 case LOC_CONST_BYTES
:
447 memcpy (value_contents_raw (v
), SYMBOL_VALUE_BYTES (var
), len
);
448 VALUE_LVAL (v
) = not_lval
;
453 if (overlay_debugging
)
454 addr
= symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var
),
455 SYMBOL_BFD_SECTION (var
));
457 addr
= SYMBOL_VALUE_ADDRESS (var
);
462 /* The import slot does not have a real address in it from the
463 dynamic loader (dld.sl on HP-UX), if the target hasn't
464 begun execution yet, so check for that. */
467 if (!target_has_execution
)
469 Attempt to access variable defined in different shared object or load module when\n\
470 addresses have not been bound by the dynamic loader. Try again when executable is running."));
472 locaddr
= SYMBOL_VALUE_ADDRESS (var
);
473 loc
= value_at (lookup_pointer_type (type
), locaddr
);
474 addr
= value_as_address (loc
);
481 addr
= get_frame_args_address (frame
);
484 addr
+= SYMBOL_VALUE (var
);
493 argref
= get_frame_args_address (frame
);
496 argref
+= SYMBOL_VALUE (var
);
497 ref
= value_at (lookup_pointer_type (type
), argref
);
498 addr
= value_as_address (ref
);
506 addr
= get_frame_locals_address (frame
);
507 addr
+= SYMBOL_VALUE (var
);
511 case LOC_BASEREG_ARG
:
512 case LOC_HP_THREAD_LOCAL_STATIC
:
514 struct value
*regval
;
516 regval
= value_from_register (lookup_pointer_type (type
),
517 SYMBOL_BASEREG (var
), frame
);
519 error (_("Value of base register not available."));
520 addr
= value_as_address (regval
);
521 addr
+= SYMBOL_VALUE (var
);
526 error (_("Cannot look up value of a typedef"));
530 if (overlay_debugging
)
531 VALUE_ADDRESS (v
) = symbol_overlayed_address
532 (BLOCK_START (SYMBOL_BLOCK_VALUE (var
)), SYMBOL_BFD_SECTION (var
));
534 VALUE_ADDRESS (v
) = BLOCK_START (SYMBOL_BLOCK_VALUE (var
));
539 case LOC_REGPARM_ADDR
:
542 int regno
= SYMBOL_VALUE (var
);
543 struct value
*regval
;
547 b
= get_frame_block (frame
, 0);
549 if (SYMBOL_CLASS (var
) == LOC_REGPARM_ADDR
)
551 regval
= value_from_register (lookup_pointer_type (type
),
556 error (_("Value of register variable not available."));
558 addr
= value_as_address (regval
);
559 VALUE_LVAL (v
) = lval_memory
;
563 regval
= value_from_register (type
, regno
, frame
);
566 error (_("Value of register variable not available."));
573 case LOC_COMPUTED_ARG
:
574 /* FIXME: cagney/2004-01-26: It should be possible to
575 unconditionally call the SYMBOL_OPS method when available.
576 Unfortunately DWARF 2 stores the frame-base (instead of the
577 function) location in a function's symbol. Oops! For the
578 moment enable this when/where applicable. */
579 if (frame
== 0 && SYMBOL_OPS (var
)->read_needs_frame (var
))
581 return SYMBOL_OPS (var
)->read_variable (var
, frame
);
585 struct minimal_symbol
*msym
;
587 msym
= lookup_minimal_symbol (DEPRECATED_SYMBOL_NAME (var
), NULL
, NULL
);
590 if (overlay_debugging
)
591 addr
= symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (msym
),
592 SYMBOL_BFD_SECTION (msym
));
594 addr
= SYMBOL_VALUE_ADDRESS (msym
);
598 case LOC_OPTIMIZED_OUT
:
599 VALUE_LVAL (v
) = not_lval
;
600 set_value_optimized_out (v
, 1);
604 error (_("Cannot look up value of a botched symbol."));
608 VALUE_ADDRESS (v
) = addr
;
609 set_value_lazy (v
, 1);
613 /* Install default attributes for register values. */
616 default_value_from_register (struct type
*type
, int regnum
,
617 struct frame_info
*frame
)
619 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
620 int len
= TYPE_LENGTH (type
);
621 struct value
*value
= allocate_value (type
);
623 VALUE_LVAL (value
) = lval_register
;
624 VALUE_FRAME_ID (value
) = get_frame_id (frame
);
625 VALUE_REGNUM (value
) = regnum
;
627 /* Any structure stored in more than one register will always be
628 an integral number of registers. Otherwise, you need to do
629 some fiddling with the last register copied here for little
631 if (gdbarch_byte_order (gdbarch
) == BFD_ENDIAN_BIG
632 && len
< register_size (gdbarch
, regnum
))
633 /* Big-endian, and we want less than full size. */
634 set_value_offset (value
, register_size (gdbarch
, regnum
) - len
);
636 set_value_offset (value
, 0);
641 /* Return a value of type TYPE, stored in register REGNUM, in frame FRAME. */
644 value_from_register (struct type
*type
, int regnum
, struct frame_info
*frame
)
646 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
647 struct type
*type1
= check_typedef (type
);
650 if (gdbarch_convert_register_p (gdbarch
, regnum
, type1
))
652 /* The ISA/ABI need to something weird when obtaining the
653 specified value from this register. It might need to
654 re-order non-adjacent, starting with REGNUM (see MIPS and
655 i386). It might need to convert the [float] register into
656 the corresponding [integer] type (see Alpha). The assumption
657 is that gdbarch_register_to_value populates the entire value
658 including the location. */
659 v
= allocate_value (type
);
660 VALUE_LVAL (v
) = lval_register
;
661 VALUE_FRAME_ID (v
) = get_frame_id (frame
);
662 VALUE_REGNUM (v
) = regnum
;
663 gdbarch_register_to_value (gdbarch
,
664 frame
, regnum
, type1
, value_contents_raw (v
));
668 int len
= TYPE_LENGTH (type
);
670 /* Construct the value. */
671 v
= gdbarch_value_from_register (gdbarch
, type
, regnum
, frame
);
674 if (!get_frame_register_bytes (frame
, regnum
, value_offset (v
), len
,
675 value_contents_raw (v
)))
676 set_value_optimized_out (v
, 1);
681 /* Return contents of register REGNUM in frame FRAME as address,
682 interpreted as value of type TYPE. Will abort if register
683 value is not available. */
686 address_from_register (struct type
*type
, int regnum
, struct frame_info
*frame
)
691 value
= value_from_register (type
, regnum
, frame
);
694 result
= value_as_address (value
);
695 release_value (value
);
702 /* Given a struct symbol for a variable or function,
703 and a stack frame id,
704 return a (pointer to a) struct value containing the properly typed
708 locate_var_value (struct symbol
*var
, struct frame_info
*frame
)
710 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
712 struct type
*type
= SYMBOL_TYPE (var
);
713 struct value
*lazy_value
;
715 /* Evaluate it first; if the result is a memory address, we're fine.
716 Lazy evaluation pays off here. */
718 lazy_value
= read_var_value (var
, frame
);
720 error (_("Address of \"%s\" is unknown."), SYMBOL_PRINT_NAME (var
));
722 if ((VALUE_LVAL (lazy_value
) == lval_memory
&& value_lazy (lazy_value
))
723 || TYPE_CODE (type
) == TYPE_CODE_FUNC
)
727 addr
= VALUE_ADDRESS (lazy_value
);
728 val
= value_from_pointer (lookup_pointer_type (type
), addr
);
732 /* Not a memory address; check what the problem was. */
733 switch (VALUE_LVAL (lazy_value
))
736 gdb_assert (gdbarch_register_name
737 (gdbarch
, VALUE_REGNUM (lazy_value
)) != NULL
738 && *gdbarch_register_name
739 (gdbarch
, VALUE_REGNUM (lazy_value
)) != '\0');
740 error (_("Address requested for identifier "
741 "\"%s\" which is in register $%s"),
742 SYMBOL_PRINT_NAME (var
),
743 gdbarch_register_name (gdbarch
, VALUE_REGNUM (lazy_value
)));
747 error (_("Can't take address of \"%s\" which isn't an lvalue."),
748 SYMBOL_PRINT_NAME (var
));
751 return 0; /* For lint -- never reached */