1 /* Find a variable's value in memory, for GDB, the GNU debugger.
3 Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
4 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2003, 2004 Free Software
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., 59 Temple Place - Suite 330,
22 Boston, MA 02111-1307, 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 void *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 (TARGET_BYTE_ORDER
== 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 void *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 (TARGET_BYTE_ORDER
== 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 void *addr
, int orig_len
, LONGEST
*pval
)
122 char *p
, *first_addr
;
126 if (TARGET_BYTE_ORDER
== BFD_ENDIAN_BIG
)
128 for (p
= (char *) addr
;
129 len
> (int) sizeof (LONGEST
) && p
< (char *) addr
+ orig_len
;
141 first_addr
= (char *) addr
;
142 for (p
= (char *) addr
+ orig_len
- 1;
143 len
> (int) sizeof (LONGEST
) && p
>= (char *) 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 void *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 POINTER_TO_ADDRESS (type
, buf
);
180 store_signed_integer (void *addr
, int len
, LONGEST val
)
183 unsigned char *startaddr
= (unsigned char *) addr
;
184 unsigned char *endaddr
= startaddr
+ len
;
186 /* Start at the least significant end of the integer, and work towards
187 the most significant. */
188 if (TARGET_BYTE_ORDER
== BFD_ENDIAN_BIG
)
190 for (p
= endaddr
- 1; p
>= startaddr
; --p
)
198 for (p
= startaddr
; p
< endaddr
; ++p
)
207 store_unsigned_integer (void *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 (TARGET_BYTE_ORDER
== 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 (void *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 ADDRESS_TO_POINTER (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().
253 NOTE: returns NULL if register value is not available. Caller will
254 check return value or die! */
257 value_of_register (int regnum
, struct frame_info
*frame
)
261 struct value
*reg_val
;
263 char raw_buffer
[MAX_REGISTER_SIZE
];
266 /* User registers lie completely outside of the range of normal
267 registers. Catch them early so that the target never sees them. */
268 if (regnum
>= NUM_REGS
+ NUM_PSEUDO_REGS
)
269 return value_of_user_reg (regnum
, frame
);
271 frame_register (frame
, regnum
, &optim
, &lval
, &addr
, &realnum
, raw_buffer
);
273 /* FIXME: cagney/2002-05-15: This test is just bogus.
275 It indicates that the target failed to supply a value for a
276 register because it was "not available" at this time. Problem
277 is, the target still has the register and so get saved_register()
278 may be returning a value saved on the stack. */
280 if (register_cached (regnum
) < 0)
281 return NULL
; /* register value not available */
283 reg_val
= allocate_value (register_type (current_gdbarch
, regnum
));
285 memcpy (VALUE_CONTENTS_RAW (reg_val
), raw_buffer
,
286 register_size (current_gdbarch
, regnum
));
287 VALUE_LVAL (reg_val
) = lval
;
288 VALUE_ADDRESS (reg_val
) = addr
;
289 VALUE_REGNUM (reg_val
) = regnum
;
290 VALUE_OPTIMIZED_OUT (reg_val
) = optim
;
294 /* Given a pointer of type TYPE in target form in BUF, return the
295 address it represents. */
297 unsigned_pointer_to_address (struct type
*type
, const void *buf
)
299 return extract_unsigned_integer (buf
, TYPE_LENGTH (type
));
303 signed_pointer_to_address (struct type
*type
, const void *buf
)
305 return extract_signed_integer (buf
, TYPE_LENGTH (type
));
308 /* Given an address, store it as a pointer of type TYPE in target
311 unsigned_address_to_pointer (struct type
*type
, void *buf
, CORE_ADDR addr
)
313 store_unsigned_integer (buf
, TYPE_LENGTH (type
), addr
);
317 address_to_signed_pointer (struct type
*type
, void *buf
, CORE_ADDR addr
)
319 store_signed_integer (buf
, TYPE_LENGTH (type
), addr
);
322 /* Will calling read_var_value or locate_var_value on SYM end
323 up caring what frame it is being evaluated relative to? SYM must
326 symbol_read_needs_frame (struct symbol
*sym
)
328 switch (SYMBOL_CLASS (sym
))
330 /* All cases listed explicitly so that gcc -Wall will detect it if
331 we failed to consider one. */
333 case LOC_COMPUTED_ARG
:
334 /* FIXME: cagney/2004-01-26: It should be possible to
335 unconditionally call the SYMBOL_OPS method when available.
336 Unfortunately DWARF 2 stores the frame-base (instead of the
337 function) location in a function's symbol. Oops! For the
338 moment enable this when/where applicable. */
339 return SYMBOL_OPS (sym
)->read_needs_frame (sym
);
345 case LOC_REGPARM_ADDR
:
349 case LOC_BASEREG_ARG
:
350 case LOC_HP_THREAD_LOCAL_STATIC
:
360 /* Getting the address of a label can be done independently of the block,
361 even if some *uses* of that address wouldn't work so well without
365 case LOC_CONST_BYTES
:
367 case LOC_OPTIMIZED_OUT
:
373 /* Given a struct symbol for a variable,
374 and a stack frame id, read the value of the variable
375 and return a (pointer to a) struct value containing the value.
376 If the variable cannot be found, return a zero pointer.
377 If FRAME is NULL, use the deprecated_selected_frame. */
380 read_var_value (struct symbol
*var
, struct frame_info
*frame
)
383 struct type
*type
= SYMBOL_TYPE (var
);
387 v
= allocate_value (type
);
388 VALUE_LVAL (v
) = lval_memory
; /* The most likely possibility. */
390 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
:
425 bytes_addr
= SYMBOL_VALUE_BYTES (var
);
426 memcpy (VALUE_CONTENTS_RAW (v
), bytes_addr
, len
);
427 VALUE_LVAL (v
) = not_lval
;
432 if (overlay_debugging
)
433 addr
= symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var
),
434 SYMBOL_BFD_SECTION (var
));
436 addr
= SYMBOL_VALUE_ADDRESS (var
);
441 /* The import slot does not have a real address in it from the
442 dynamic loader (dld.sl on HP-UX), if the target hasn't
443 begun execution yet, so check for that. */
446 if (!target_has_execution
)
448 Attempt to access variable defined in different shared object or load module when\n\
449 addresses have not been bound by the dynamic loader. Try again when executable is running.");
451 locaddr
= SYMBOL_VALUE_ADDRESS (var
);
452 loc
= value_at (lookup_pointer_type (type
), locaddr
);
453 addr
= value_as_address (loc
);
459 addr
= get_frame_args_address (frame
);
462 addr
+= SYMBOL_VALUE (var
);
471 argref
= get_frame_args_address (frame
);
474 argref
+= SYMBOL_VALUE (var
);
475 ref
= value_at (lookup_pointer_type (type
), argref
);
476 addr
= value_as_address (ref
);
484 addr
= get_frame_locals_address (frame
);
485 addr
+= SYMBOL_VALUE (var
);
489 case LOC_BASEREG_ARG
:
490 case LOC_HP_THREAD_LOCAL_STATIC
:
492 struct value
*regval
;
494 regval
= value_from_register (lookup_pointer_type (type
),
495 SYMBOL_BASEREG (var
), frame
);
497 error ("Value of base register not available.");
498 addr
= value_as_address (regval
);
499 addr
+= SYMBOL_VALUE (var
);
504 error ("Cannot look up value of a typedef");
508 if (overlay_debugging
)
509 VALUE_ADDRESS (v
) = symbol_overlayed_address
510 (BLOCK_START (SYMBOL_BLOCK_VALUE (var
)), SYMBOL_BFD_SECTION (var
));
512 VALUE_ADDRESS (v
) = BLOCK_START (SYMBOL_BLOCK_VALUE (var
));
517 case LOC_REGPARM_ADDR
:
520 int regno
= SYMBOL_VALUE (var
);
521 struct value
*regval
;
525 b
= get_frame_block (frame
, 0);
527 if (SYMBOL_CLASS (var
) == LOC_REGPARM_ADDR
)
529 regval
= value_from_register (lookup_pointer_type (type
),
534 error ("Value of register variable not available.");
536 addr
= value_as_address (regval
);
537 VALUE_LVAL (v
) = lval_memory
;
541 regval
= value_from_register (type
, regno
, frame
);
544 error ("Value of register variable not available.");
551 case LOC_COMPUTED_ARG
:
552 /* FIXME: cagney/2004-01-26: It should be possible to
553 unconditionally call the SYMBOL_OPS method when available.
554 Unfortunately DWARF 2 stores the frame-base (instead of the
555 function) location in a function's symbol. Oops! For the
556 moment enable this when/where applicable. */
557 if (frame
== 0 && SYMBOL_OPS (var
)->read_needs_frame (var
))
559 return SYMBOL_OPS (var
)->read_variable (var
, frame
);
563 struct minimal_symbol
*msym
;
565 msym
= lookup_minimal_symbol (DEPRECATED_SYMBOL_NAME (var
), NULL
, NULL
);
568 if (overlay_debugging
)
569 addr
= symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (msym
),
570 SYMBOL_BFD_SECTION (msym
));
572 addr
= SYMBOL_VALUE_ADDRESS (msym
);
576 case LOC_OPTIMIZED_OUT
:
577 VALUE_LVAL (v
) = not_lval
;
578 VALUE_OPTIMIZED_OUT (v
) = 1;
582 error ("Cannot look up value of a botched symbol.");
586 VALUE_ADDRESS (v
) = addr
;
591 /* Return a value of type TYPE, stored in register REGNUM, in frame
594 NOTE: returns NULL if register value is not available.
595 Caller will check return value or die! */
598 value_from_register (struct type
*type
, int regnum
, struct frame_info
*frame
)
600 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
601 struct value
*v
= allocate_value (type
);
602 CHECK_TYPEDEF (type
);
604 if (TYPE_LENGTH (type
) == 0)
606 /* It doesn't matter much what we return for this: since the
607 length is zero, it could be anything. But if allowed to see
608 a zero-length type, the register-finding loop below will set
609 neither mem_stor nor reg_stor, and then report an internal
612 Zero-length types can legitimately arise from declarations
613 like 'struct {}' (a GCC extension, not valid ISO C). GDB may
614 also create them when it finds bogus debugging information;
615 for example, in GCC 2.95.4 and binutils 2.11.93.0.2, the
616 STABS BINCL->EXCL compression process can create bad type
617 numbers. GDB reads these as TYPE_CODE_UNDEF types, with zero
618 length. (That bug is actually the only known way to get a
619 zero-length value allocated to a register --- which is what
620 it takes to make it here.)
622 We'll just attribute the value to the original register. */
623 VALUE_LVAL (v
) = lval_register
;
624 VALUE_ADDRESS (v
) = regnum
;
625 VALUE_REGNUM (v
) = regnum
;
627 else if (CONVERT_REGISTER_P (regnum
, type
))
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 REGISTER_TO_VALUE (frame
, regnum
, type
, VALUE_CONTENTS_RAW (v
));
637 VALUE_LVAL (v
) = lval_reg_frame_relative
;
638 VALUE_FRAME_ID (v
) = get_frame_id (frame
);
639 VALUE_REGNUM (v
) = regnum
;
644 int mem_stor
= 0, reg_stor
= 0;
645 int mem_tracking
= 1;
646 CORE_ADDR last_addr
= 0;
647 CORE_ADDR first_addr
= 0;
648 int first_realnum
= regnum
;
649 int len
= TYPE_LENGTH (type
);
650 int value_bytes_copied
;
652 char *value_bytes
= (char *) alloca (len
+ MAX_REGISTER_SIZE
);
654 /* Copy all of the data out, whereever it may be. */
655 for (local_regnum
= regnum
, value_bytes_copied
= 0;
656 value_bytes_copied
< len
;
657 (value_bytes_copied
+= register_size (current_gdbarch
, local_regnum
),
664 frame_register (frame
, local_regnum
, &optim
, &lval
, &addr
,
665 &realnum
, value_bytes
+ value_bytes_copied
);
667 if (register_cached (local_regnum
) == -1)
668 return NULL
; /* register value not available */
670 if (regnum
== local_regnum
)
673 first_realnum
= realnum
;
675 if (lval
== lval_register
)
681 mem_tracking
= (mem_tracking
682 && (regnum
== local_regnum
683 || addr
== last_addr
));
688 /* FIXME: cagney/2003-06-04: Shouldn't this always use
689 lval_reg_frame_relative? If it doesn't and the register's
690 location changes (say after a resume) then this value is
691 going to have wrong information. */
692 if ((reg_stor
&& mem_stor
)
693 || (mem_stor
&& !mem_tracking
))
694 /* Mixed storage; all of the hassle we just went through was
695 for some good purpose. */
697 VALUE_LVAL (v
) = lval_reg_frame_relative
;
698 VALUE_FRAME_ID (v
) = get_frame_id (frame
);
699 VALUE_REGNUM (v
) = regnum
;
703 VALUE_LVAL (v
) = lval_memory
;
704 VALUE_ADDRESS (v
) = first_addr
;
708 VALUE_LVAL (v
) = lval_register
;
709 VALUE_ADDRESS (v
) = first_addr
;
710 VALUE_REGNUM (v
) = first_realnum
;
713 internal_error (__FILE__
, __LINE__
,
714 "value_from_register: Value not stored anywhere!");
716 VALUE_OPTIMIZED_OUT (v
) = optimized
;
718 /* Any structure stored in more than one register will always be
719 an integral number of registers. Otherwise, you need to do
720 some fiddling with the last register copied here for little
722 if (TARGET_BYTE_ORDER
== BFD_ENDIAN_BIG
723 && len
< register_size (current_gdbarch
, regnum
))
724 /* Big-endian, and we want less than full size. */
725 v
->offset
= register_size (current_gdbarch
, regnum
) - len
;
728 memcpy (VALUE_CONTENTS_RAW (v
), value_bytes
+ value_offset (v
), len
);
734 /* Given a struct symbol for a variable or function,
735 and a stack frame id,
736 return a (pointer to a) struct value containing the properly typed
740 locate_var_value (struct symbol
*var
, struct frame_info
*frame
)
743 struct type
*type
= SYMBOL_TYPE (var
);
744 struct value
*lazy_value
;
746 /* Evaluate it first; if the result is a memory address, we're fine.
747 Lazy evaluation pays off here. */
749 lazy_value
= read_var_value (var
, frame
);
751 error ("Address of \"%s\" is unknown.", SYMBOL_PRINT_NAME (var
));
753 if (VALUE_LAZY (lazy_value
)
754 || TYPE_CODE (type
) == TYPE_CODE_FUNC
)
758 addr
= VALUE_ADDRESS (lazy_value
);
759 val
= value_from_pointer (lookup_pointer_type (type
), addr
);
763 /* Not a memory address; check what the problem was. */
764 switch (VALUE_LVAL (lazy_value
))
767 gdb_assert (REGISTER_NAME (VALUE_REGNUM (lazy_value
)) != NULL
768 && *REGISTER_NAME (VALUE_REGNUM (lazy_value
)) != '\0');
769 error("Address requested for identifier "
770 "\"%s\" which is in register $%s",
771 SYMBOL_PRINT_NAME (var
),
772 REGISTER_NAME (VALUE_REGNUM (lazy_value
)));
775 case lval_reg_frame_relative
:
776 gdb_assert (REGISTER_NAME (VALUE_REGNUM (lazy_value
)) != NULL
777 && *REGISTER_NAME (VALUE_REGNUM (lazy_value
)) != '\0');
778 error("Address requested for identifier "
779 "\"%s\" which is in frame register $%s",
780 SYMBOL_PRINT_NAME (var
),
781 REGISTER_NAME (VALUE_REGNUM (lazy_value
)));
785 error ("Can't take address of \"%s\" which isn't an lvalue.",
786 SYMBOL_PRINT_NAME (var
));
789 return 0; /* For lint -- never reached */