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 /* FIXME: cagney/2004-01-26: It should be possible to
349 unconditionally call the SYMBOL_OPS method when available.
350 Unfortunately DWARF 2 stores the frame-base (instead of the
351 function) location in a function's symbol. Oops! For the
352 moment enable this when/where applicable. */
353 return SYMBOL_OPS (sym
)->read_needs_frame (sym
);
358 case LOC_REGPARM_ADDR
:
368 /* Getting the address of a label can be done independently of the block,
369 even if some *uses* of that address wouldn't work so well without
373 case LOC_CONST_BYTES
:
375 case LOC_OPTIMIZED_OUT
:
381 /* Given a struct symbol for a variable,
382 and a stack frame id, read the value of the variable
383 and return a (pointer to a) struct value containing the value.
384 If the variable cannot be found, return a zero pointer.
385 If FRAME is NULL, use the selected frame. */
388 read_var_value (struct symbol
*var
, struct frame_info
*frame
)
391 struct type
*type
= SYMBOL_TYPE (var
);
395 if (SYMBOL_CLASS (var
) == LOC_COMPUTED
396 || SYMBOL_CLASS (var
) == LOC_REGISTER
)
397 /* These cases do not use V. */
401 v
= allocate_value (type
);
402 VALUE_LVAL (v
) = lval_memory
; /* The most likely possibility. */
405 len
= TYPE_LENGTH (type
);
407 /* FIXME drow/2003-09-06: this call to the selected frame should be
408 pushed upwards to the callers. */
410 frame
= deprecated_safe_get_selected_frame ();
412 switch (SYMBOL_CLASS (var
))
415 /* Put the constant back in target format. */
416 store_signed_integer (value_contents_raw (v
), len
,
417 (LONGEST
) SYMBOL_VALUE (var
));
418 VALUE_LVAL (v
) = not_lval
;
422 /* Put the constant back in target format. */
423 if (overlay_debugging
)
426 = symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var
),
427 SYMBOL_OBJ_SECTION (var
));
428 store_typed_address (value_contents_raw (v
), type
, addr
);
431 store_typed_address (value_contents_raw (v
), type
,
432 SYMBOL_VALUE_ADDRESS (var
));
433 VALUE_LVAL (v
) = not_lval
;
436 case LOC_CONST_BYTES
:
438 memcpy (value_contents_raw (v
), SYMBOL_VALUE_BYTES (var
), len
);
439 VALUE_LVAL (v
) = not_lval
;
444 if (overlay_debugging
)
445 addr
= symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var
),
446 SYMBOL_OBJ_SECTION (var
));
448 addr
= SYMBOL_VALUE_ADDRESS (var
);
454 addr
= get_frame_args_address (frame
);
457 addr
+= SYMBOL_VALUE (var
);
466 argref
= get_frame_args_address (frame
);
469 argref
+= SYMBOL_VALUE (var
);
470 ref
= value_at (lookup_pointer_type (type
), argref
);
471 addr
= value_as_address (ref
);
478 addr
= get_frame_locals_address (frame
);
479 addr
+= SYMBOL_VALUE (var
);
483 error (_("Cannot look up value of a typedef"));
487 if (overlay_debugging
)
488 VALUE_ADDRESS (v
) = symbol_overlayed_address
489 (BLOCK_START (SYMBOL_BLOCK_VALUE (var
)), SYMBOL_OBJ_SECTION (var
));
491 VALUE_ADDRESS (v
) = BLOCK_START (SYMBOL_BLOCK_VALUE (var
));
495 case LOC_REGPARM_ADDR
:
497 int regno
= SYMBOL_VALUE (var
);
498 struct value
*regval
;
503 if (SYMBOL_CLASS (var
) == LOC_REGPARM_ADDR
)
505 regval
= value_from_register (lookup_pointer_type (type
),
510 error (_("Value of register variable not available."));
512 addr
= value_as_address (regval
);
513 VALUE_LVAL (v
) = lval_memory
;
517 regval
= value_from_register (type
, regno
, frame
);
520 error (_("Value of register variable not available."));
527 /* FIXME: cagney/2004-01-26: It should be possible to
528 unconditionally call the SYMBOL_OPS method when available.
529 Unfortunately DWARF 2 stores the frame-base (instead of the
530 function) location in a function's symbol. Oops! For the
531 moment enable this when/where applicable. */
532 if (frame
== 0 && SYMBOL_OPS (var
)->read_needs_frame (var
))
534 return SYMBOL_OPS (var
)->read_variable (var
, frame
);
538 struct minimal_symbol
*msym
;
540 msym
= lookup_minimal_symbol (SYMBOL_LINKAGE_NAME (var
), NULL
, NULL
);
543 if (overlay_debugging
)
544 addr
= symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (msym
),
545 SYMBOL_OBJ_SECTION (msym
));
547 addr
= SYMBOL_VALUE_ADDRESS (msym
);
551 case LOC_OPTIMIZED_OUT
:
552 VALUE_LVAL (v
) = not_lval
;
553 set_value_optimized_out (v
, 1);
557 error (_("Cannot look up value of a botched symbol."));
561 VALUE_ADDRESS (v
) = addr
;
562 set_value_lazy (v
, 1);
566 /* Install default attributes for register values. */
569 default_value_from_register (struct type
*type
, int regnum
,
570 struct frame_info
*frame
)
572 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
573 int len
= TYPE_LENGTH (type
);
574 struct value
*value
= allocate_value (type
);
576 VALUE_LVAL (value
) = lval_register
;
577 VALUE_FRAME_ID (value
) = get_frame_id (frame
);
578 VALUE_REGNUM (value
) = regnum
;
580 /* Any structure stored in more than one register will always be
581 an integral number of registers. Otherwise, you need to do
582 some fiddling with the last register copied here for little
584 if (gdbarch_byte_order (gdbarch
) == BFD_ENDIAN_BIG
585 && len
< register_size (gdbarch
, regnum
))
586 /* Big-endian, and we want less than full size. */
587 set_value_offset (value
, register_size (gdbarch
, regnum
) - len
);
589 set_value_offset (value
, 0);
594 /* Return a value of type TYPE, stored in register REGNUM, in frame FRAME. */
597 value_from_register (struct type
*type
, int regnum
, struct frame_info
*frame
)
599 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
600 struct type
*type1
= check_typedef (type
);
603 if (gdbarch_convert_register_p (gdbarch
, regnum
, type1
))
605 /* The ISA/ABI need to something weird when obtaining the
606 specified value from this register. It might need to
607 re-order non-adjacent, starting with REGNUM (see MIPS and
608 i386). It might need to convert the [float] register into
609 the corresponding [integer] type (see Alpha). The assumption
610 is that gdbarch_register_to_value populates the entire value
611 including the location. */
612 v
= allocate_value (type
);
613 VALUE_LVAL (v
) = lval_register
;
614 VALUE_FRAME_ID (v
) = get_frame_id (frame
);
615 VALUE_REGNUM (v
) = regnum
;
616 gdbarch_register_to_value (gdbarch
,
617 frame
, regnum
, type1
, value_contents_raw (v
));
621 int len
= TYPE_LENGTH (type
);
623 /* Construct the value. */
624 v
= gdbarch_value_from_register (gdbarch
, type
, regnum
, frame
);
627 if (!get_frame_register_bytes (frame
, regnum
, value_offset (v
), len
,
628 value_contents_raw (v
)))
629 set_value_optimized_out (v
, 1);
634 /* Return contents of register REGNUM in frame FRAME as address,
635 interpreted as value of type TYPE. Will abort if register
636 value is not available. */
639 address_from_register (struct type
*type
, int regnum
, struct frame_info
*frame
)
644 value
= value_from_register (type
, regnum
, frame
);
647 result
= value_as_address (value
);
648 release_value (value
);
655 /* Given a struct symbol for a variable or function,
656 and a stack frame id,
657 return a (pointer to a) struct value containing the properly typed
661 locate_var_value (struct symbol
*var
, struct frame_info
*frame
)
663 struct gdbarch
*gdbarch
;
665 struct type
*type
= SYMBOL_TYPE (var
);
666 struct value
*lazy_value
;
668 /* Evaluate it first; if the result is a memory address, we're fine.
669 Lazy evaluation pays off here. */
671 lazy_value
= read_var_value (var
, frame
);
673 error (_("Address of \"%s\" is unknown."), SYMBOL_PRINT_NAME (var
));
675 if ((VALUE_LVAL (lazy_value
) == lval_memory
&& value_lazy (lazy_value
))
676 || TYPE_CODE (type
) == TYPE_CODE_FUNC
)
680 addr
= VALUE_ADDRESS (lazy_value
);
681 val
= value_from_pointer (lookup_pointer_type (type
), addr
);
685 /* Not a memory address; check what the problem was. */
686 switch (VALUE_LVAL (lazy_value
))
690 gdbarch
= get_frame_arch (frame
);
691 gdb_assert (gdbarch_register_name
692 (gdbarch
, VALUE_REGNUM (lazy_value
)) != NULL
693 && *gdbarch_register_name
694 (gdbarch
, VALUE_REGNUM (lazy_value
)) != '\0');
695 error (_("Address requested for identifier "
696 "\"%s\" which is in register $%s"),
697 SYMBOL_PRINT_NAME (var
),
698 gdbarch_register_name (gdbarch
, VALUE_REGNUM (lazy_value
)));
702 error (_("Can't take address of \"%s\" which isn't an lvalue."),
703 SYMBOL_PRINT_NAME (var
));
706 return 0; /* For lint -- never reached */
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