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, 2005 Free
5 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., 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 set_value_optimized_out (reg_val
, optim
);
291 VALUE_FRAME_ID (reg_val
) = get_frame_id (frame
);
295 /* Given a pointer of type TYPE in target form in BUF, return the
296 address it represents. */
298 unsigned_pointer_to_address (struct type
*type
, const void *buf
)
300 return extract_unsigned_integer (buf
, TYPE_LENGTH (type
));
304 signed_pointer_to_address (struct type
*type
, const void *buf
)
306 return extract_signed_integer (buf
, TYPE_LENGTH (type
));
309 /* Given an address, store it as a pointer of type TYPE in target
312 unsigned_address_to_pointer (struct type
*type
, void *buf
, CORE_ADDR addr
)
314 store_unsigned_integer (buf
, TYPE_LENGTH (type
), addr
);
318 address_to_signed_pointer (struct type
*type
, void *buf
, CORE_ADDR addr
)
320 store_signed_integer (buf
, TYPE_LENGTH (type
), addr
);
323 /* Will calling read_var_value or locate_var_value on SYM end
324 up caring what frame it is being evaluated relative to? SYM must
327 symbol_read_needs_frame (struct symbol
*sym
)
329 switch (SYMBOL_CLASS (sym
))
331 /* All cases listed explicitly so that gcc -Wall will detect it if
332 we failed to consider one. */
334 case LOC_COMPUTED_ARG
:
335 /* FIXME: cagney/2004-01-26: It should be possible to
336 unconditionally call the SYMBOL_OPS method when available.
337 Unfortunately DWARF 2 stores the frame-base (instead of the
338 function) location in a function's symbol. Oops! For the
339 moment enable this when/where applicable. */
340 return SYMBOL_OPS (sym
)->read_needs_frame (sym
);
346 case LOC_REGPARM_ADDR
:
350 case LOC_BASEREG_ARG
:
351 case LOC_HP_THREAD_LOCAL_STATIC
:
361 /* Getting the address of a label can be done independently of the block,
362 even if some *uses* of that address wouldn't work so well without
366 case LOC_CONST_BYTES
:
368 case LOC_OPTIMIZED_OUT
:
374 /* Given a struct symbol for a variable,
375 and a stack frame id, read the value of the variable
376 and return a (pointer to a) struct value containing the value.
377 If the variable cannot be found, return a zero pointer.
378 If FRAME is NULL, use the deprecated_selected_frame. */
381 read_var_value (struct symbol
*var
, struct frame_info
*frame
)
384 struct type
*type
= SYMBOL_TYPE (var
);
388 if (SYMBOL_CLASS (var
) == LOC_COMPUTED
389 || SYMBOL_CLASS (var
) == LOC_COMPUTED_ARG
390 || SYMBOL_CLASS (var
) == LOC_REGISTER
391 || SYMBOL_CLASS (var
) == LOC_REGPARM
)
392 /* These cases do not use V. */
396 v
= allocate_value (type
);
397 VALUE_LVAL (v
) = lval_memory
; /* The most likely possibility. */
400 len
= TYPE_LENGTH (type
);
402 /* FIXME drow/2003-09-06: this call to the selected frame should be
403 pushed upwards to the callers. */
405 frame
= deprecated_safe_get_selected_frame ();
407 switch (SYMBOL_CLASS (var
))
410 /* Put the constant back in target format. */
411 store_signed_integer (value_contents_raw (v
), len
,
412 (LONGEST
) SYMBOL_VALUE (var
));
413 VALUE_LVAL (v
) = not_lval
;
417 /* Put the constant back in target format. */
418 if (overlay_debugging
)
421 = symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var
),
422 SYMBOL_BFD_SECTION (var
));
423 store_typed_address (value_contents_raw (v
), type
, addr
);
426 store_typed_address (value_contents_raw (v
), type
,
427 SYMBOL_VALUE_ADDRESS (var
));
428 VALUE_LVAL (v
) = not_lval
;
431 case LOC_CONST_BYTES
:
434 bytes_addr
= SYMBOL_VALUE_BYTES (var
);
435 memcpy (value_contents_raw (v
), bytes_addr
, len
);
436 VALUE_LVAL (v
) = not_lval
;
441 if (overlay_debugging
)
442 addr
= symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var
),
443 SYMBOL_BFD_SECTION (var
));
445 addr
= SYMBOL_VALUE_ADDRESS (var
);
450 /* The import slot does not have a real address in it from the
451 dynamic loader (dld.sl on HP-UX), if the target hasn't
452 begun execution yet, so check for that. */
455 if (!target_has_execution
)
457 Attempt to access variable defined in different shared object or load module when\n\
458 addresses have not been bound by the dynamic loader. Try again when executable is running."));
460 locaddr
= SYMBOL_VALUE_ADDRESS (var
);
461 loc
= value_at (lookup_pointer_type (type
), locaddr
);
462 addr
= value_as_address (loc
);
469 addr
= get_frame_args_address (frame
);
472 addr
+= SYMBOL_VALUE (var
);
481 argref
= get_frame_args_address (frame
);
484 argref
+= SYMBOL_VALUE (var
);
485 ref
= value_at (lookup_pointer_type (type
), argref
);
486 addr
= value_as_address (ref
);
494 addr
= get_frame_locals_address (frame
);
495 addr
+= SYMBOL_VALUE (var
);
499 case LOC_BASEREG_ARG
:
500 case LOC_HP_THREAD_LOCAL_STATIC
:
502 struct value
*regval
;
504 regval
= value_from_register (lookup_pointer_type (type
),
505 SYMBOL_BASEREG (var
), frame
);
507 error (_("Value of base register not available."));
508 addr
= value_as_address (regval
);
509 addr
+= SYMBOL_VALUE (var
);
514 error (_("Cannot look up value of a typedef"));
518 if (overlay_debugging
)
519 VALUE_ADDRESS (v
) = symbol_overlayed_address
520 (BLOCK_START (SYMBOL_BLOCK_VALUE (var
)), SYMBOL_BFD_SECTION (var
));
522 VALUE_ADDRESS (v
) = BLOCK_START (SYMBOL_BLOCK_VALUE (var
));
527 case LOC_REGPARM_ADDR
:
530 int regno
= SYMBOL_VALUE (var
);
531 struct value
*regval
;
535 b
= get_frame_block (frame
, 0);
537 if (SYMBOL_CLASS (var
) == LOC_REGPARM_ADDR
)
539 regval
= value_from_register (lookup_pointer_type (type
),
544 error (_("Value of register variable not available."));
546 addr
= value_as_address (regval
);
547 VALUE_LVAL (v
) = lval_memory
;
551 regval
= value_from_register (type
, regno
, frame
);
554 error (_("Value of register variable not available."));
561 case LOC_COMPUTED_ARG
:
562 /* FIXME: cagney/2004-01-26: It should be possible to
563 unconditionally call the SYMBOL_OPS method when available.
564 Unfortunately DWARF 2 stores the frame-base (instead of the
565 function) location in a function's symbol. Oops! For the
566 moment enable this when/where applicable. */
567 if (frame
== 0 && SYMBOL_OPS (var
)->read_needs_frame (var
))
569 return SYMBOL_OPS (var
)->read_variable (var
, frame
);
573 struct minimal_symbol
*msym
;
575 msym
= lookup_minimal_symbol (DEPRECATED_SYMBOL_NAME (var
), NULL
, NULL
);
578 if (overlay_debugging
)
579 addr
= symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (msym
),
580 SYMBOL_BFD_SECTION (msym
));
582 addr
= SYMBOL_VALUE_ADDRESS (msym
);
586 case LOC_OPTIMIZED_OUT
:
587 VALUE_LVAL (v
) = not_lval
;
588 set_value_optimized_out (v
, 1);
592 error (_("Cannot look up value of a botched symbol."));
596 VALUE_ADDRESS (v
) = addr
;
597 set_value_lazy (v
, 1);
601 /* Return a value of type TYPE, stored in register REGNUM, in frame
604 NOTE: returns NULL if register value is not available.
605 Caller will check return value or die! */
608 value_from_register (struct type
*type
, int regnum
, struct frame_info
*frame
)
610 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
611 struct value
*v
= allocate_value (type
);
612 CHECK_TYPEDEF (type
);
614 if (TYPE_LENGTH (type
) == 0)
616 /* It doesn't matter much what we return for this: since the
617 length is zero, it could be anything. But if allowed to see
618 a zero-length type, the register-finding loop below will set
619 neither mem_stor nor reg_stor, and then report an internal
622 Zero-length types can legitimately arise from declarations
623 like 'struct {}' (a GCC extension, not valid ISO C). GDB may
624 also create them when it finds bogus debugging information;
625 for example, in GCC 2.95.4 and binutils 2.11.93.0.2, the
626 STABS BINCL->EXCL compression process can create bad type
627 numbers. GDB reads these as TYPE_CODE_UNDEF types, with zero
628 length. (That bug is actually the only known way to get a
629 zero-length value allocated to a register --- which is what
630 it takes to make it here.)
632 We'll just attribute the value to the original register. */
633 VALUE_LVAL (v
) = lval_register
;
634 VALUE_ADDRESS (v
) = regnum
;
635 VALUE_REGNUM (v
) = regnum
;
637 else if (CONVERT_REGISTER_P (regnum
, type
))
639 /* The ISA/ABI need to something weird when obtaining the
640 specified value from this register. It might need to
641 re-order non-adjacent, starting with REGNUM (see MIPS and
642 i386). It might need to convert the [float] register into
643 the corresponding [integer] type (see Alpha). The assumption
644 is that REGISTER_TO_VALUE populates the entire value
645 including the location. */
646 REGISTER_TO_VALUE (frame
, regnum
, type
, value_contents_raw (v
));
647 VALUE_LVAL (v
) = lval_register
;
648 VALUE_FRAME_ID (v
) = get_frame_id (frame
);
649 VALUE_REGNUM (v
) = regnum
;
654 int mem_stor
= 0, reg_stor
= 0;
655 int mem_tracking
= 1;
656 CORE_ADDR last_addr
= 0;
657 CORE_ADDR first_addr
= 0;
658 int first_realnum
= regnum
;
659 int len
= TYPE_LENGTH (type
);
660 int value_bytes_copied
;
662 char *value_bytes
= (char *) alloca (len
+ MAX_REGISTER_SIZE
);
664 /* Copy all of the data out, whereever it may be. */
665 for (local_regnum
= regnum
, value_bytes_copied
= 0;
666 value_bytes_copied
< len
;
667 (value_bytes_copied
+= register_size (current_gdbarch
, local_regnum
),
674 frame_register (frame
, local_regnum
, &optim
, &lval
, &addr
,
675 &realnum
, value_bytes
+ value_bytes_copied
);
677 if (register_cached (local_regnum
) == -1)
678 return NULL
; /* register value not available */
680 if (regnum
== local_regnum
)
683 first_realnum
= realnum
;
685 if (lval
== lval_register
)
691 /* FIXME: cagney/2004-11-12: I think this is trying to
692 check that the stored registers are adjacent in
693 memory. It isn't doing a good job? */
694 mem_tracking
= (mem_tracking
695 && (regnum
== local_regnum
696 || addr
== last_addr
));
701 if (mem_tracking
&& mem_stor
&& !reg_stor
)
703 VALUE_LVAL (v
) = lval_memory
;
704 VALUE_ADDRESS (v
) = first_addr
;
708 VALUE_LVAL (v
) = lval_register
;
709 VALUE_FRAME_ID (v
) = get_frame_id (frame
);
710 VALUE_REGNUM (v
) = regnum
;
713 set_value_optimized_out (v
, optimized
);
715 /* Any structure stored in more than one register will always be
716 an integral number of registers. Otherwise, you need to do
717 some fiddling with the last register copied here for little
719 if (TARGET_BYTE_ORDER
== BFD_ENDIAN_BIG
720 && len
< register_size (current_gdbarch
, regnum
))
721 /* Big-endian, and we want less than full size. */
722 set_value_offset (v
, register_size (current_gdbarch
, regnum
) - len
);
724 set_value_offset (v
, 0);
725 memcpy (value_contents_raw (v
), value_bytes
+ value_offset (v
), len
);
731 /* Given a struct symbol for a variable or function,
732 and a stack frame id,
733 return a (pointer to a) struct value containing the properly typed
737 locate_var_value (struct symbol
*var
, struct frame_info
*frame
)
740 struct type
*type
= SYMBOL_TYPE (var
);
741 struct value
*lazy_value
;
743 /* Evaluate it first; if the result is a memory address, we're fine.
744 Lazy evaluation pays off here. */
746 lazy_value
= read_var_value (var
, frame
);
748 error (_("Address of \"%s\" is unknown."), SYMBOL_PRINT_NAME (var
));
750 if (value_lazy (lazy_value
)
751 || TYPE_CODE (type
) == TYPE_CODE_FUNC
)
755 addr
= VALUE_ADDRESS (lazy_value
);
756 val
= value_from_pointer (lookup_pointer_type (type
), addr
);
760 /* Not a memory address; check what the problem was. */
761 switch (VALUE_LVAL (lazy_value
))
764 gdb_assert (REGISTER_NAME (VALUE_REGNUM (lazy_value
)) != NULL
765 && *REGISTER_NAME (VALUE_REGNUM (lazy_value
)) != '\0');
766 error (_("Address requested for identifier "
767 "\"%s\" which is in register $%s"),
768 SYMBOL_PRINT_NAME (var
),
769 REGISTER_NAME (VALUE_REGNUM (lazy_value
)));
773 error (_("Can't take address of \"%s\" which isn't an lvalue."),
774 SYMBOL_PRINT_NAME (var
));
777 return 0; /* For lint -- never reached */