13dea02ad1dea145ffad40ba3cc9c4a6b02aa5cd
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
:
370 /* Getting the address of a label can be done independently of the block,
371 even if some *uses* of that address wouldn't work so well without
375 case LOC_CONST_BYTES
:
377 case LOC_OPTIMIZED_OUT
:
383 /* Given a struct symbol for a variable,
384 and a stack frame id, read the value of the variable
385 and return a (pointer to a) struct value containing the value.
386 If the variable cannot be found, return a zero pointer.
387 If FRAME is NULL, use the selected frame. */
390 read_var_value (struct symbol
*var
, struct frame_info
*frame
)
393 struct type
*type
= SYMBOL_TYPE (var
);
397 if (SYMBOL_CLASS (var
) == LOC_COMPUTED
398 || SYMBOL_CLASS (var
) == LOC_COMPUTED_ARG
399 || SYMBOL_CLASS (var
) == LOC_REGISTER
400 || SYMBOL_CLASS (var
) == LOC_REGPARM
)
401 /* These cases do not use V. */
405 v
= allocate_value (type
);
406 VALUE_LVAL (v
) = lval_memory
; /* The most likely possibility. */
409 len
= TYPE_LENGTH (type
);
411 /* FIXME drow/2003-09-06: this call to the selected frame should be
412 pushed upwards to the callers. */
414 frame
= deprecated_safe_get_selected_frame ();
416 switch (SYMBOL_CLASS (var
))
419 /* Put the constant back in target format. */
420 store_signed_integer (value_contents_raw (v
), len
,
421 (LONGEST
) SYMBOL_VALUE (var
));
422 VALUE_LVAL (v
) = not_lval
;
426 /* Put the constant back in target format. */
427 if (overlay_debugging
)
430 = symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var
),
431 SYMBOL_BFD_SECTION (var
));
432 store_typed_address (value_contents_raw (v
), type
, addr
);
435 store_typed_address (value_contents_raw (v
), type
,
436 SYMBOL_VALUE_ADDRESS (var
));
437 VALUE_LVAL (v
) = not_lval
;
440 case LOC_CONST_BYTES
:
442 memcpy (value_contents_raw (v
), SYMBOL_VALUE_BYTES (var
), len
);
443 VALUE_LVAL (v
) = not_lval
;
448 if (overlay_debugging
)
449 addr
= symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var
),
450 SYMBOL_BFD_SECTION (var
));
452 addr
= SYMBOL_VALUE_ADDRESS (var
);
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
);
482 addr
= get_frame_locals_address (frame
);
483 addr
+= SYMBOL_VALUE (var
);
487 error (_("Cannot look up value of a typedef"));
491 if (overlay_debugging
)
492 VALUE_ADDRESS (v
) = symbol_overlayed_address
493 (BLOCK_START (SYMBOL_BLOCK_VALUE (var
)), SYMBOL_BFD_SECTION (var
));
495 VALUE_ADDRESS (v
) = BLOCK_START (SYMBOL_BLOCK_VALUE (var
));
500 case LOC_REGPARM_ADDR
:
503 int regno
= SYMBOL_VALUE (var
);
504 struct value
*regval
;
508 b
= get_frame_block (frame
, 0);
510 if (SYMBOL_CLASS (var
) == LOC_REGPARM_ADDR
)
512 regval
= value_from_register (lookup_pointer_type (type
),
517 error (_("Value of register variable not available."));
519 addr
= value_as_address (regval
);
520 VALUE_LVAL (v
) = lval_memory
;
524 regval
= value_from_register (type
, regno
, frame
);
527 error (_("Value of register variable not available."));
534 case LOC_COMPUTED_ARG
:
535 /* FIXME: cagney/2004-01-26: It should be possible to
536 unconditionally call the SYMBOL_OPS method when available.
537 Unfortunately DWARF 2 stores the frame-base (instead of the
538 function) location in a function's symbol. Oops! For the
539 moment enable this when/where applicable. */
540 if (frame
== 0 && SYMBOL_OPS (var
)->read_needs_frame (var
))
542 return SYMBOL_OPS (var
)->read_variable (var
, frame
);
546 struct minimal_symbol
*msym
;
548 msym
= lookup_minimal_symbol (DEPRECATED_SYMBOL_NAME (var
), NULL
, NULL
);
551 if (overlay_debugging
)
552 addr
= symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (msym
),
553 SYMBOL_BFD_SECTION (msym
));
555 addr
= SYMBOL_VALUE_ADDRESS (msym
);
559 case LOC_OPTIMIZED_OUT
:
560 VALUE_LVAL (v
) = not_lval
;
561 set_value_optimized_out (v
, 1);
565 error (_("Cannot look up value of a botched symbol."));
569 VALUE_ADDRESS (v
) = addr
;
570 set_value_lazy (v
, 1);
574 /* Install default attributes for register values. */
577 default_value_from_register (struct type
*type
, int regnum
,
578 struct frame_info
*frame
)
580 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
581 int len
= TYPE_LENGTH (type
);
582 struct value
*value
= allocate_value (type
);
584 VALUE_LVAL (value
) = lval_register
;
585 VALUE_FRAME_ID (value
) = get_frame_id (frame
);
586 VALUE_REGNUM (value
) = regnum
;
588 /* Any structure stored in more than one register will always be
589 an integral number of registers. Otherwise, you need to do
590 some fiddling with the last register copied here for little
592 if (gdbarch_byte_order (gdbarch
) == BFD_ENDIAN_BIG
593 && len
< register_size (gdbarch
, regnum
))
594 /* Big-endian, and we want less than full size. */
595 set_value_offset (value
, register_size (gdbarch
, regnum
) - len
);
597 set_value_offset (value
, 0);
602 /* Return a value of type TYPE, stored in register REGNUM, in frame FRAME. */
605 value_from_register (struct type
*type
, int regnum
, struct frame_info
*frame
)
607 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
608 struct type
*type1
= check_typedef (type
);
611 if (gdbarch_convert_register_p (gdbarch
, regnum
, type1
))
613 /* The ISA/ABI need to something weird when obtaining the
614 specified value from this register. It might need to
615 re-order non-adjacent, starting with REGNUM (see MIPS and
616 i386). It might need to convert the [float] register into
617 the corresponding [integer] type (see Alpha). The assumption
618 is that gdbarch_register_to_value populates the entire value
619 including the location. */
620 v
= allocate_value (type
);
621 VALUE_LVAL (v
) = lval_register
;
622 VALUE_FRAME_ID (v
) = get_frame_id (frame
);
623 VALUE_REGNUM (v
) = regnum
;
624 gdbarch_register_to_value (gdbarch
,
625 frame
, regnum
, type1
, value_contents_raw (v
));
629 int len
= TYPE_LENGTH (type
);
631 /* Construct the value. */
632 v
= gdbarch_value_from_register (gdbarch
, type
, regnum
, frame
);
635 if (!get_frame_register_bytes (frame
, regnum
, value_offset (v
), len
,
636 value_contents_raw (v
)))
637 set_value_optimized_out (v
, 1);
642 /* Return contents of register REGNUM in frame FRAME as address,
643 interpreted as value of type TYPE. Will abort if register
644 value is not available. */
647 address_from_register (struct type
*type
, int regnum
, struct frame_info
*frame
)
652 value
= value_from_register (type
, regnum
, frame
);
655 result
= value_as_address (value
);
656 release_value (value
);
663 /* Given a struct symbol for a variable or function,
664 and a stack frame id,
665 return a (pointer to a) struct value containing the properly typed
669 locate_var_value (struct symbol
*var
, struct frame_info
*frame
)
671 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
673 struct type
*type
= SYMBOL_TYPE (var
);
674 struct value
*lazy_value
;
676 /* Evaluate it first; if the result is a memory address, we're fine.
677 Lazy evaluation pays off here. */
679 lazy_value
= read_var_value (var
, frame
);
681 error (_("Address of \"%s\" is unknown."), SYMBOL_PRINT_NAME (var
));
683 if ((VALUE_LVAL (lazy_value
) == lval_memory
&& value_lazy (lazy_value
))
684 || TYPE_CODE (type
) == TYPE_CODE_FUNC
)
688 addr
= VALUE_ADDRESS (lazy_value
);
689 val
= value_from_pointer (lookup_pointer_type (type
), addr
);
693 /* Not a memory address; check what the problem was. */
694 switch (VALUE_LVAL (lazy_value
))
697 gdb_assert (gdbarch_register_name
698 (gdbarch
, VALUE_REGNUM (lazy_value
)) != NULL
699 && *gdbarch_register_name
700 (gdbarch
, VALUE_REGNUM (lazy_value
)) != '\0');
701 error (_("Address requested for identifier "
702 "\"%s\" which is in register $%s"),
703 SYMBOL_PRINT_NAME (var
),
704 gdbarch_register_name (gdbarch
, VALUE_REGNUM (lazy_value
)));
708 error (_("Can't take address of \"%s\" which isn't an lvalue."),
709 SYMBOL_PRINT_NAME (var
));
712 return 0; /* For lint -- never reached */
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