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 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 completly 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 /* Convert raw data to virtual format if necessary. */
287 if (DEPRECATED_REGISTER_CONVERTIBLE (regnum
))
289 DEPRECATED_REGISTER_CONVERT_TO_VIRTUAL (regnum
, register_type (current_gdbarch
, regnum
),
290 raw_buffer
, VALUE_CONTENTS_RAW (reg_val
));
292 else if (REGISTER_RAW_SIZE (regnum
) == REGISTER_VIRTUAL_SIZE (regnum
))
293 memcpy (VALUE_CONTENTS_RAW (reg_val
), raw_buffer
,
294 REGISTER_RAW_SIZE (regnum
));
296 internal_error (__FILE__
, __LINE__
,
297 "Register \"%s\" (%d) has conflicting raw (%d) and virtual (%d) size",
298 REGISTER_NAME (regnum
),
300 REGISTER_RAW_SIZE (regnum
),
301 REGISTER_VIRTUAL_SIZE (regnum
));
302 VALUE_LVAL (reg_val
) = lval
;
303 VALUE_ADDRESS (reg_val
) = addr
;
304 VALUE_REGNO (reg_val
) = regnum
;
305 VALUE_OPTIMIZED_OUT (reg_val
) = optim
;
309 /* Given a pointer of type TYPE in target form in BUF, return the
310 address it represents. */
312 unsigned_pointer_to_address (struct type
*type
, const void *buf
)
314 return extract_unsigned_integer (buf
, TYPE_LENGTH (type
));
318 signed_pointer_to_address (struct type
*type
, const void *buf
)
320 return extract_signed_integer (buf
, TYPE_LENGTH (type
));
323 /* Given an address, store it as a pointer of type TYPE in target
326 unsigned_address_to_pointer (struct type
*type
, void *buf
, CORE_ADDR addr
)
328 store_unsigned_integer (buf
, TYPE_LENGTH (type
), addr
);
332 address_to_signed_pointer (struct type
*type
, void *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
:
350 struct location_funcs
*symfuncs
= SYMBOL_LOCATION_FUNCS (sym
);
351 return (symfuncs
->read_needs_frame
) (sym
);
359 case LOC_REGPARM_ADDR
:
363 case LOC_BASEREG_ARG
:
364 case LOC_HP_THREAD_LOCAL_STATIC
:
374 /* Getting the address of a label can be done independently of the block,
375 even if some *uses* of that address wouldn't work so well without
379 case LOC_CONST_BYTES
:
381 case LOC_OPTIMIZED_OUT
:
387 /* Given a struct symbol for a variable,
388 and a stack frame id, read the value of the variable
389 and return a (pointer to a) struct value containing the value.
390 If the variable cannot be found, return a zero pointer.
391 If FRAME is NULL, use the deprecated_selected_frame. */
394 read_var_value (register struct symbol
*var
, struct frame_info
*frame
)
396 register struct value
*v
;
397 struct type
*type
= SYMBOL_TYPE (var
);
401 v
= allocate_value (type
);
402 VALUE_LVAL (v
) = lval_memory
; /* The most likely possibility. */
403 VALUE_BFD_SECTION (v
) = SYMBOL_BFD_SECTION (var
);
405 len
= TYPE_LENGTH (type
);
408 frame
= deprecated_selected_frame
;
410 switch (SYMBOL_CLASS (var
))
413 /* Put the constant back in target format. */
414 store_signed_integer (VALUE_CONTENTS_RAW (v
), len
,
415 (LONGEST
) SYMBOL_VALUE (var
));
416 VALUE_LVAL (v
) = not_lval
;
420 /* Put the constant back in target format. */
421 if (overlay_debugging
)
424 = symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var
),
425 SYMBOL_BFD_SECTION (var
));
426 store_typed_address (VALUE_CONTENTS_RAW (v
), type
, addr
);
429 store_typed_address (VALUE_CONTENTS_RAW (v
), type
,
430 SYMBOL_VALUE_ADDRESS (var
));
431 VALUE_LVAL (v
) = not_lval
;
434 case LOC_CONST_BYTES
:
437 bytes_addr
= SYMBOL_VALUE_BYTES (var
);
438 memcpy (VALUE_CONTENTS_RAW (v
), bytes_addr
, len
);
439 VALUE_LVAL (v
) = not_lval
;
444 if (overlay_debugging
)
445 addr
= symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var
),
446 SYMBOL_BFD_SECTION (var
));
448 addr
= SYMBOL_VALUE_ADDRESS (var
);
453 /* The import slot does not have a real address in it from the
454 dynamic loader (dld.sl on HP-UX), if the target hasn't
455 begun execution yet, so check for that. */
458 if (!target_has_execution
)
460 Attempt to access variable defined in different shared object or load module when\n\
461 addresses have not been bound by the dynamic loader. Try again when executable is running.");
463 locaddr
= SYMBOL_VALUE_ADDRESS (var
);
464 loc
= value_at (lookup_pointer_type (type
), locaddr
, NULL
);
465 addr
= value_as_address (loc
);
471 addr
= get_frame_args_address (frame
);
474 addr
+= SYMBOL_VALUE (var
);
483 argref
= get_frame_args_address (frame
);
486 argref
+= SYMBOL_VALUE (var
);
487 ref
= value_at (lookup_pointer_type (type
), argref
, NULL
);
488 addr
= value_as_address (ref
);
496 addr
= get_frame_locals_address (frame
);
497 addr
+= SYMBOL_VALUE (var
);
501 case LOC_BASEREG_ARG
:
502 case LOC_HP_THREAD_LOCAL_STATIC
:
504 struct value
*regval
;
506 regval
= value_from_register (lookup_pointer_type (type
),
507 SYMBOL_BASEREG (var
), frame
);
509 error ("Value of base register not available.");
510 addr
= value_as_address (regval
);
511 addr
+= SYMBOL_VALUE (var
);
516 error ("Cannot look up value of a typedef");
520 if (overlay_debugging
)
521 VALUE_ADDRESS (v
) = symbol_overlayed_address
522 (BLOCK_START (SYMBOL_BLOCK_VALUE (var
)), SYMBOL_BFD_SECTION (var
));
524 VALUE_ADDRESS (v
) = BLOCK_START (SYMBOL_BLOCK_VALUE (var
));
529 case LOC_REGPARM_ADDR
:
532 int regno
= SYMBOL_VALUE (var
);
533 struct value
*regval
;
537 b
= get_frame_block (frame
, 0);
539 if (SYMBOL_CLASS (var
) == LOC_REGPARM_ADDR
)
541 regval
= value_from_register (lookup_pointer_type (type
),
546 error ("Value of register variable not available.");
548 addr
= value_as_address (regval
);
549 VALUE_LVAL (v
) = lval_memory
;
553 regval
= value_from_register (type
, regno
, frame
);
556 error ("Value of register variable not available.");
563 case LOC_COMPUTED_ARG
:
565 struct location_funcs
*funcs
= SYMBOL_LOCATION_FUNCS (var
);
567 if (frame
== 0 && (funcs
->read_needs_frame
) (var
))
569 return (funcs
->read_variable
) (var
, frame
);
576 struct minimal_symbol
*msym
;
578 msym
= lookup_minimal_symbol (DEPRECATED_SYMBOL_NAME (var
), NULL
, NULL
);
581 if (overlay_debugging
)
582 addr
= symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (msym
),
583 SYMBOL_BFD_SECTION (msym
));
585 addr
= SYMBOL_VALUE_ADDRESS (msym
);
589 case LOC_OPTIMIZED_OUT
:
590 VALUE_LVAL (v
) = not_lval
;
591 VALUE_OPTIMIZED_OUT (v
) = 1;
595 error ("Cannot look up value of a botched symbol.");
599 VALUE_ADDRESS (v
) = addr
;
604 /* Return a value of type TYPE, stored in register REGNUM, in frame
607 NOTE: returns NULL if register value is not available.
608 Caller will check return value or die! */
611 value_from_register (struct type
*type
, int regnum
, struct frame_info
*frame
)
613 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
614 struct value
*v
= allocate_value (type
);
615 CHECK_TYPEDEF (type
);
617 if (CONVERT_REGISTER_P (regnum
, type
))
619 /* The ISA/ABI need to something weird when obtaining the
620 specified value from this register. It might need to
621 re-order non-adjacent, starting with REGNUM (see MIPS and
622 i386). It might need to convert the [float] register into
623 the corresponding [integer] type (see Alpha). The assumption
624 is that REGISTER_TO_VALUE populates the entire value
625 including the location. */
626 REGISTER_TO_VALUE (frame
, regnum
, type
, VALUE_CONTENTS_RAW (v
));
627 VALUE_LVAL (v
) = lval_reg_frame_relative
;
628 VALUE_FRAME_ID (v
) = get_frame_id (frame
);
629 VALUE_FRAME_REGNUM (v
) = regnum
;
634 int mem_stor
= 0, reg_stor
= 0;
635 int mem_tracking
= 1;
636 CORE_ADDR last_addr
= 0;
637 CORE_ADDR first_addr
= 0;
638 int first_realnum
= regnum
;
639 int len
= TYPE_LENGTH (type
);
640 int value_bytes_copied
;
642 char *value_bytes
= (char *) alloca (len
+ MAX_REGISTER_SIZE
);
644 /* Copy all of the data out, whereever it may be. */
645 for (local_regnum
= regnum
, value_bytes_copied
= 0;
646 value_bytes_copied
< len
;
647 (value_bytes_copied
+= REGISTER_RAW_SIZE (local_regnum
),
654 frame_register (frame
, local_regnum
, &optim
, &lval
, &addr
,
655 &realnum
, value_bytes
+ value_bytes_copied
);
657 if (register_cached (local_regnum
) == -1)
658 return NULL
; /* register value not available */
660 if (regnum
== local_regnum
)
663 first_realnum
= realnum
;
665 if (lval
== lval_register
)
671 mem_tracking
= (mem_tracking
672 && (regnum
== local_regnum
673 || addr
== last_addr
));
678 /* FIXME: cagney/2003-06-04: Shouldn't this always use
679 lval_reg_frame_relative? If it doesn't and the register's
680 location changes (say after a resume) then this value is
681 going to have wrong information. */
682 if ((reg_stor
&& mem_stor
)
683 || (mem_stor
&& !mem_tracking
))
684 /* Mixed storage; all of the hassle we just went through was
685 for some good purpose. */
687 VALUE_LVAL (v
) = lval_reg_frame_relative
;
688 VALUE_FRAME_ID (v
) = get_frame_id (frame
);
689 VALUE_FRAME_REGNUM (v
) = regnum
;
693 VALUE_LVAL (v
) = lval_memory
;
694 VALUE_ADDRESS (v
) = first_addr
;
698 VALUE_LVAL (v
) = lval_register
;
699 VALUE_ADDRESS (v
) = first_addr
;
700 VALUE_REGNO (v
) = first_realnum
;
703 internal_error (__FILE__
, __LINE__
,
704 "value_from_register: Value not stored anywhere!");
706 VALUE_OPTIMIZED_OUT (v
) = optimized
;
708 /* Any structure stored in more than one register will always be
709 an integral number of registers. Otherwise, you need to do
710 some fiddling with the last register copied here for little
712 if (TARGET_BYTE_ORDER
== BFD_ENDIAN_BIG
713 && len
< REGISTER_RAW_SIZE (regnum
))
714 /* Big-endian, and we want less than full size. */
715 VALUE_OFFSET (v
) = REGISTER_RAW_SIZE (regnum
) - len
;
717 VALUE_OFFSET (v
) = 0;
718 memcpy (VALUE_CONTENTS_RAW (v
), value_bytes
+ VALUE_OFFSET (v
), len
);
724 /* Given a struct symbol for a variable or function,
725 and a stack frame id,
726 return a (pointer to a) struct value containing the properly typed
730 locate_var_value (register struct symbol
*var
, struct frame_info
*frame
)
733 struct type
*type
= SYMBOL_TYPE (var
);
734 struct value
*lazy_value
;
736 /* Evaluate it first; if the result is a memory address, we're fine.
737 Lazy evaluation pays off here. */
739 lazy_value
= read_var_value (var
, frame
);
741 error ("Address of \"%s\" is unknown.", SYMBOL_PRINT_NAME (var
));
743 if (VALUE_LAZY (lazy_value
)
744 || TYPE_CODE (type
) == TYPE_CODE_FUNC
)
748 addr
= VALUE_ADDRESS (lazy_value
);
749 val
= value_from_pointer (lookup_pointer_type (type
), addr
);
750 VALUE_BFD_SECTION (val
) = VALUE_BFD_SECTION (lazy_value
);
754 /* Not a memory address; check what the problem was. */
755 switch (VALUE_LVAL (lazy_value
))
758 gdb_assert (REGISTER_NAME (VALUE_REGNO (lazy_value
)) != NULL
759 && *REGISTER_NAME (VALUE_REGNO (lazy_value
)) != '\0');
760 error("Address requested for identifier "
761 "\"%s\" which is in register $%s",
762 SYMBOL_PRINT_NAME (var
),
763 REGISTER_NAME (VALUE_REGNO (lazy_value
)));
766 case lval_reg_frame_relative
:
767 gdb_assert (REGISTER_NAME (VALUE_FRAME_REGNUM (lazy_value
)) != NULL
768 && *REGISTER_NAME (VALUE_FRAME_REGNUM (lazy_value
)) != '\0');
769 error("Address requested for identifier "
770 "\"%s\" which is in frame register $%s",
771 SYMBOL_PRINT_NAME (var
),
772 REGISTER_NAME (VALUE_FRAME_REGNUM (lazy_value
)));
776 error ("Can't take address of \"%s\" which isn't an lvalue.",
777 SYMBOL_PRINT_NAME (var
));
780 return 0; /* For lint -- never reached */