1 /* Low level packing and unpacking of values for GDB, the GNU Debugger.
3 Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
4 1995, 1996, 1997, 1998, 1999, 2000, 2002, 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. */
25 #include "gdb_string.h"
37 #include "gdb_assert.h"
41 /* Prototypes for exported functions. */
43 void _initialize_values (void);
45 /* Prototypes for local functions. */
47 static void show_values (char *, int);
49 static void show_convenience (char *, int);
52 /* The value-history records all the values printed
53 by print commands during this session. Each chunk
54 records 60 consecutive values. The first chunk on
55 the chain records the most recent values.
56 The total number of values is in value_history_count. */
58 #define VALUE_HISTORY_CHUNK 60
60 struct value_history_chunk
62 struct value_history_chunk
*next
;
63 struct value
*values
[VALUE_HISTORY_CHUNK
];
66 /* Chain of chunks now in use. */
68 static struct value_history_chunk
*value_history_chain
;
70 static int value_history_count
; /* Abs number of last entry stored */
72 /* List of all value objects currently allocated
73 (except for those released by calls to release_value)
74 This is so they can be freed after each command. */
76 static struct value
*all_values
;
78 /* Allocate a value that has the correct length for type TYPE. */
81 allocate_value (struct type
*type
)
84 struct type
*atype
= check_typedef (type
);
86 val
= (struct value
*) xmalloc (sizeof (struct value
) + TYPE_LENGTH (atype
));
87 val
->next
= all_values
;
90 val
->enclosing_type
= type
;
91 VALUE_LVAL (val
) = not_lval
;
92 VALUE_ADDRESS (val
) = 0;
93 VALUE_FRAME_ID (val
) = null_frame_id
;
97 VALUE_REGNUM (val
) = -1;
99 VALUE_OPTIMIZED_OUT (val
) = 0;
100 VALUE_EMBEDDED_OFFSET (val
) = 0;
101 VALUE_POINTED_TO_OFFSET (val
) = 0;
106 /* Allocate a value that has the correct length
107 for COUNT repetitions type TYPE. */
110 allocate_repeat_value (struct type
*type
, int count
)
112 int low_bound
= current_language
->string_lower_bound
; /* ??? */
113 /* FIXME-type-allocation: need a way to free this type when we are
115 struct type
*range_type
116 = create_range_type ((struct type
*) NULL
, builtin_type_int
,
117 low_bound
, count
+ low_bound
- 1);
118 /* FIXME-type-allocation: need a way to free this type when we are
120 return allocate_value (create_array_type ((struct type
*) NULL
,
124 /* Accessor methods. */
127 value_type (struct value
*value
)
133 value_offset (struct value
*value
)
135 return value
->offset
;
139 value_bitpos (struct value
*value
)
141 return value
->bitpos
;
145 value_bitsize (struct value
*value
)
147 return value
->bitsize
;
151 value_contents_raw (struct value
*value
)
153 return value
->aligner
.contents
+ value
->embedded_offset
;
157 value_contents_all_raw (struct value
*value
)
159 return value
->aligner
.contents
;
163 value_enclosing_type (struct value
*value
)
165 return value
->enclosing_type
;
169 value_contents_all (struct value
*value
)
172 value_fetch_lazy (value
);
173 return value
->aligner
.contents
;
177 value_lazy (struct value
*value
)
183 /* Return a mark in the value chain. All values allocated after the
184 mark is obtained (except for those released) are subject to being freed
185 if a subsequent value_free_to_mark is passed the mark. */
192 /* Free all values allocated since MARK was obtained by value_mark
193 (except for those released). */
195 value_free_to_mark (struct value
*mark
)
200 for (val
= all_values
; val
&& val
!= mark
; val
= next
)
208 /* Free all the values that have been allocated (except for those released).
209 Called after each command, successful or not. */
212 free_all_values (void)
217 for (val
= all_values
; val
; val
= next
)
226 /* Remove VAL from the chain all_values
227 so it will not be freed automatically. */
230 release_value (struct value
*val
)
234 if (all_values
== val
)
236 all_values
= val
->next
;
240 for (v
= all_values
; v
; v
= v
->next
)
250 /* Release all values up to mark */
252 value_release_to_mark (struct value
*mark
)
257 for (val
= next
= all_values
; next
; next
= next
->next
)
258 if (next
->next
== mark
)
260 all_values
= next
->next
;
268 /* Return a copy of the value ARG.
269 It contains the same contents, for same memory address,
270 but it's a different block of storage. */
273 value_copy (struct value
*arg
)
275 struct type
*encl_type
= value_enclosing_type (arg
);
276 struct value
*val
= allocate_value (encl_type
);
277 val
->type
= arg
->type
;
278 VALUE_LVAL (val
) = VALUE_LVAL (arg
);
279 VALUE_ADDRESS (val
) = VALUE_ADDRESS (arg
);
280 val
->offset
= arg
->offset
;
281 val
->bitpos
= arg
->bitpos
;
282 val
->bitsize
= arg
->bitsize
;
283 VALUE_FRAME_ID (val
) = VALUE_FRAME_ID (arg
);
284 VALUE_REGNUM (val
) = VALUE_REGNUM (arg
);
285 val
->lazy
= arg
->lazy
;
286 VALUE_OPTIMIZED_OUT (val
) = VALUE_OPTIMIZED_OUT (arg
);
287 VALUE_EMBEDDED_OFFSET (val
) = VALUE_EMBEDDED_OFFSET (arg
);
288 VALUE_POINTED_TO_OFFSET (val
) = VALUE_POINTED_TO_OFFSET (arg
);
289 val
->modifiable
= arg
->modifiable
;
290 if (!value_lazy (val
))
292 memcpy (value_contents_all_raw (val
), value_contents_all_raw (arg
),
293 TYPE_LENGTH (value_enclosing_type (arg
)));
299 /* Access to the value history. */
301 /* Record a new value in the value history.
302 Returns the absolute history index of the entry.
303 Result of -1 indicates the value was not saved; otherwise it is the
304 value history index of this new item. */
307 record_latest_value (struct value
*val
)
311 /* We don't want this value to have anything to do with the inferior anymore.
312 In particular, "set $1 = 50" should not affect the variable from which
313 the value was taken, and fast watchpoints should be able to assume that
314 a value on the value history never changes. */
315 if (value_lazy (val
))
316 value_fetch_lazy (val
);
317 /* We preserve VALUE_LVAL so that the user can find out where it was fetched
318 from. This is a bit dubious, because then *&$1 does not just return $1
319 but the current contents of that location. c'est la vie... */
323 /* Here we treat value_history_count as origin-zero
324 and applying to the value being stored now. */
326 i
= value_history_count
% VALUE_HISTORY_CHUNK
;
329 struct value_history_chunk
*new
330 = (struct value_history_chunk
*)
331 xmalloc (sizeof (struct value_history_chunk
));
332 memset (new->values
, 0, sizeof new->values
);
333 new->next
= value_history_chain
;
334 value_history_chain
= new;
337 value_history_chain
->values
[i
] = val
;
339 /* Now we regard value_history_count as origin-one
340 and applying to the value just stored. */
342 return ++value_history_count
;
345 /* Return a copy of the value in the history with sequence number NUM. */
348 access_value_history (int num
)
350 struct value_history_chunk
*chunk
;
355 absnum
+= value_history_count
;
360 error ("The history is empty.");
362 error ("There is only one value in the history.");
364 error ("History does not go back to $$%d.", -num
);
366 if (absnum
> value_history_count
)
367 error ("History has not yet reached $%d.", absnum
);
371 /* Now absnum is always absolute and origin zero. */
373 chunk
= value_history_chain
;
374 for (i
= (value_history_count
- 1) / VALUE_HISTORY_CHUNK
- absnum
/ VALUE_HISTORY_CHUNK
;
378 return value_copy (chunk
->values
[absnum
% VALUE_HISTORY_CHUNK
]);
381 /* Clear the value history entirely.
382 Must be done when new symbol tables are loaded,
383 because the type pointers become invalid. */
386 clear_value_history (void)
388 struct value_history_chunk
*next
;
392 while (value_history_chain
)
394 for (i
= 0; i
< VALUE_HISTORY_CHUNK
; i
++)
395 if ((val
= value_history_chain
->values
[i
]) != NULL
)
397 next
= value_history_chain
->next
;
398 xfree (value_history_chain
);
399 value_history_chain
= next
;
401 value_history_count
= 0;
405 show_values (char *num_exp
, int from_tty
)
413 /* "info history +" should print from the stored position.
414 "info history <exp>" should print around value number <exp>. */
415 if (num_exp
[0] != '+' || num_exp
[1] != '\0')
416 num
= parse_and_eval_long (num_exp
) - 5;
420 /* "info history" means print the last 10 values. */
421 num
= value_history_count
- 9;
427 for (i
= num
; i
< num
+ 10 && i
<= value_history_count
; i
++)
429 val
= access_value_history (i
);
430 printf_filtered ("$%d = ", i
);
431 value_print (val
, gdb_stdout
, 0, Val_pretty_default
);
432 printf_filtered ("\n");
435 /* The next "info history +" should start after what we just printed. */
438 /* Hitting just return after this command should do the same thing as
439 "info history +". If num_exp is null, this is unnecessary, since
440 "info history +" is not useful after "info history". */
441 if (from_tty
&& num_exp
)
448 /* Internal variables. These are variables within the debugger
449 that hold values assigned by debugger commands.
450 The user refers to them with a '$' prefix
451 that does not appear in the variable names stored internally. */
453 static struct internalvar
*internalvars
;
455 /* Look up an internal variable with name NAME. NAME should not
456 normally include a dollar sign.
458 If the specified internal variable does not exist,
459 one is created, with a void value. */
462 lookup_internalvar (char *name
)
464 struct internalvar
*var
;
466 for (var
= internalvars
; var
; var
= var
->next
)
467 if (strcmp (var
->name
, name
) == 0)
470 var
= (struct internalvar
*) xmalloc (sizeof (struct internalvar
));
471 var
->name
= concat (name
, NULL
);
472 var
->value
= allocate_value (builtin_type_void
);
473 release_value (var
->value
);
474 var
->next
= internalvars
;
480 value_of_internalvar (struct internalvar
*var
)
484 val
= value_copy (var
->value
);
485 if (value_lazy (val
))
486 value_fetch_lazy (val
);
487 VALUE_LVAL (val
) = lval_internalvar
;
488 VALUE_INTERNALVAR (val
) = var
;
493 set_internalvar_component (struct internalvar
*var
, int offset
, int bitpos
,
494 int bitsize
, struct value
*newval
)
496 char *addr
= VALUE_CONTENTS (var
->value
) + offset
;
499 modify_field (addr
, value_as_long (newval
),
502 memcpy (addr
, VALUE_CONTENTS (newval
), TYPE_LENGTH (value_type (newval
)));
506 set_internalvar (struct internalvar
*var
, struct value
*val
)
508 struct value
*newval
;
510 newval
= value_copy (val
);
511 newval
->modifiable
= 1;
513 /* Force the value to be fetched from the target now, to avoid problems
514 later when this internalvar is referenced and the target is gone or
516 if (value_lazy (newval
))
517 value_fetch_lazy (newval
);
519 /* Begin code which must not call error(). If var->value points to
520 something free'd, an error() obviously leaves a dangling pointer.
521 But we also get a danling pointer if var->value points to
522 something in the value chain (i.e., before release_value is
523 called), because after the error free_all_values will get called before
527 release_value (newval
);
528 /* End code which must not call error(). */
532 internalvar_name (struct internalvar
*var
)
537 /* Free all internalvars. Done when new symtabs are loaded,
538 because that makes the values invalid. */
541 clear_internalvars (void)
543 struct internalvar
*var
;
548 internalvars
= var
->next
;
556 show_convenience (char *ignore
, int from_tty
)
558 struct internalvar
*var
;
561 for (var
= internalvars
; var
; var
= var
->next
)
567 printf_filtered ("$%s = ", var
->name
);
568 value_print (var
->value
, gdb_stdout
, 0, Val_pretty_default
);
569 printf_filtered ("\n");
572 printf_unfiltered ("No debugger convenience variables now defined.\n\
573 Convenience variables have names starting with \"$\";\n\
574 use \"set\" as in \"set $foo = 5\" to define them.\n");
577 /* Extract a value as a C number (either long or double).
578 Knows how to convert fixed values to double, or
579 floating values to long.
580 Does not deallocate the value. */
583 value_as_long (struct value
*val
)
585 /* This coerces arrays and functions, which is necessary (e.g.
586 in disassemble_command). It also dereferences references, which
587 I suspect is the most logical thing to do. */
588 val
= coerce_array (val
);
589 return unpack_long (value_type (val
), VALUE_CONTENTS (val
));
593 value_as_double (struct value
*val
)
598 foo
= unpack_double (value_type (val
), VALUE_CONTENTS (val
), &inv
);
600 error ("Invalid floating value found in program.");
603 /* Extract a value as a C pointer. Does not deallocate the value.
604 Note that val's type may not actually be a pointer; value_as_long
605 handles all the cases. */
607 value_as_address (struct value
*val
)
609 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
610 whether we want this to be true eventually. */
612 /* ADDR_BITS_REMOVE is wrong if we are being called for a
613 non-address (e.g. argument to "signal", "info break", etc.), or
614 for pointers to char, in which the low bits *are* significant. */
615 return ADDR_BITS_REMOVE (value_as_long (val
));
618 /* There are several targets (IA-64, PowerPC, and others) which
619 don't represent pointers to functions as simply the address of
620 the function's entry point. For example, on the IA-64, a
621 function pointer points to a two-word descriptor, generated by
622 the linker, which contains the function's entry point, and the
623 value the IA-64 "global pointer" register should have --- to
624 support position-independent code. The linker generates
625 descriptors only for those functions whose addresses are taken.
627 On such targets, it's difficult for GDB to convert an arbitrary
628 function address into a function pointer; it has to either find
629 an existing descriptor for that function, or call malloc and
630 build its own. On some targets, it is impossible for GDB to
631 build a descriptor at all: the descriptor must contain a jump
632 instruction; data memory cannot be executed; and code memory
635 Upon entry to this function, if VAL is a value of type `function'
636 (that is, TYPE_CODE (VALUE_TYPE (val)) == TYPE_CODE_FUNC), then
637 VALUE_ADDRESS (val) is the address of the function. This is what
638 you'll get if you evaluate an expression like `main'. The call
639 to COERCE_ARRAY below actually does all the usual unary
640 conversions, which includes converting values of type `function'
641 to `pointer to function'. This is the challenging conversion
642 discussed above. Then, `unpack_long' will convert that pointer
643 back into an address.
645 So, suppose the user types `disassemble foo' on an architecture
646 with a strange function pointer representation, on which GDB
647 cannot build its own descriptors, and suppose further that `foo'
648 has no linker-built descriptor. The address->pointer conversion
649 will signal an error and prevent the command from running, even
650 though the next step would have been to convert the pointer
651 directly back into the same address.
653 The following shortcut avoids this whole mess. If VAL is a
654 function, just return its address directly. */
655 if (TYPE_CODE (value_type (val
)) == TYPE_CODE_FUNC
656 || TYPE_CODE (value_type (val
)) == TYPE_CODE_METHOD
)
657 return VALUE_ADDRESS (val
);
659 val
= coerce_array (val
);
661 /* Some architectures (e.g. Harvard), map instruction and data
662 addresses onto a single large unified address space. For
663 instance: An architecture may consider a large integer in the
664 range 0x10000000 .. 0x1000ffff to already represent a data
665 addresses (hence not need a pointer to address conversion) while
666 a small integer would still need to be converted integer to
667 pointer to address. Just assume such architectures handle all
668 integer conversions in a single function. */
672 I think INTEGER_TO_ADDRESS is a good idea as proposed --- but we
673 must admonish GDB hackers to make sure its behavior matches the
674 compiler's, whenever possible.
676 In general, I think GDB should evaluate expressions the same way
677 the compiler does. When the user copies an expression out of
678 their source code and hands it to a `print' command, they should
679 get the same value the compiler would have computed. Any
680 deviation from this rule can cause major confusion and annoyance,
681 and needs to be justified carefully. In other words, GDB doesn't
682 really have the freedom to do these conversions in clever and
685 AndrewC pointed out that users aren't complaining about how GDB
686 casts integers to pointers; they are complaining that they can't
687 take an address from a disassembly listing and give it to `x/i'.
688 This is certainly important.
690 Adding an architecture method like integer_to_address() certainly
691 makes it possible for GDB to "get it right" in all circumstances
692 --- the target has complete control over how things get done, so
693 people can Do The Right Thing for their target without breaking
694 anyone else. The standard doesn't specify how integers get
695 converted to pointers; usually, the ABI doesn't either, but
696 ABI-specific code is a more reasonable place to handle it. */
698 if (TYPE_CODE (value_type (val
)) != TYPE_CODE_PTR
699 && TYPE_CODE (value_type (val
)) != TYPE_CODE_REF
700 && gdbarch_integer_to_address_p (current_gdbarch
))
701 return gdbarch_integer_to_address (current_gdbarch
, value_type (val
),
702 VALUE_CONTENTS (val
));
704 return unpack_long (value_type (val
), VALUE_CONTENTS (val
));
708 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
709 as a long, or as a double, assuming the raw data is described
710 by type TYPE. Knows how to convert different sizes of values
711 and can convert between fixed and floating point. We don't assume
712 any alignment for the raw data. Return value is in host byte order.
714 If you want functions and arrays to be coerced to pointers, and
715 references to be dereferenced, call value_as_long() instead.
717 C++: It is assumed that the front-end has taken care of
718 all matters concerning pointers to members. A pointer
719 to member which reaches here is considered to be equivalent
720 to an INT (or some size). After all, it is only an offset. */
723 unpack_long (struct type
*type
, const char *valaddr
)
725 enum type_code code
= TYPE_CODE (type
);
726 int len
= TYPE_LENGTH (type
);
727 int nosign
= TYPE_UNSIGNED (type
);
729 if (current_language
->la_language
== language_scm
730 && is_scmvalue_type (type
))
731 return scm_unpack (type
, valaddr
, TYPE_CODE_INT
);
735 case TYPE_CODE_TYPEDEF
:
736 return unpack_long (check_typedef (type
), valaddr
);
741 case TYPE_CODE_RANGE
:
743 return extract_unsigned_integer (valaddr
, len
);
745 return extract_signed_integer (valaddr
, len
);
748 return extract_typed_floating (valaddr
, type
);
752 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
753 whether we want this to be true eventually. */
754 return extract_typed_address (valaddr
, type
);
756 case TYPE_CODE_MEMBER
:
757 error ("not implemented: member types in unpack_long");
760 error ("Value can't be converted to integer.");
762 return 0; /* Placate lint. */
765 /* Return a double value from the specified type and address.
766 INVP points to an int which is set to 0 for valid value,
767 1 for invalid value (bad float format). In either case,
768 the returned double is OK to use. Argument is in target
769 format, result is in host format. */
772 unpack_double (struct type
*type
, const char *valaddr
, int *invp
)
778 *invp
= 0; /* Assume valid. */
779 CHECK_TYPEDEF (type
);
780 code
= TYPE_CODE (type
);
781 len
= TYPE_LENGTH (type
);
782 nosign
= TYPE_UNSIGNED (type
);
783 if (code
== TYPE_CODE_FLT
)
785 /* NOTE: cagney/2002-02-19: There was a test here to see if the
786 floating-point value was valid (using the macro
787 INVALID_FLOAT). That test/macro have been removed.
789 It turns out that only the VAX defined this macro and then
790 only in a non-portable way. Fixing the portability problem
791 wouldn't help since the VAX floating-point code is also badly
792 bit-rotten. The target needs to add definitions for the
793 methods TARGET_FLOAT_FORMAT and TARGET_DOUBLE_FORMAT - these
794 exactly describe the target floating-point format. The
795 problem here is that the corresponding floatformat_vax_f and
796 floatformat_vax_d values these methods should be set to are
797 also not defined either. Oops!
799 Hopefully someone will add both the missing floatformat
800 definitions and the new cases for floatformat_is_valid (). */
802 if (!floatformat_is_valid (floatformat_from_type (type
), valaddr
))
808 return extract_typed_floating (valaddr
, type
);
812 /* Unsigned -- be sure we compensate for signed LONGEST. */
813 return (ULONGEST
) unpack_long (type
, valaddr
);
817 /* Signed -- we are OK with unpack_long. */
818 return unpack_long (type
, valaddr
);
822 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
823 as a CORE_ADDR, assuming the raw data is described by type TYPE.
824 We don't assume any alignment for the raw data. Return value is in
827 If you want functions and arrays to be coerced to pointers, and
828 references to be dereferenced, call value_as_address() instead.
830 C++: It is assumed that the front-end has taken care of
831 all matters concerning pointers to members. A pointer
832 to member which reaches here is considered to be equivalent
833 to an INT (or some size). After all, it is only an offset. */
836 unpack_pointer (struct type
*type
, const char *valaddr
)
838 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
839 whether we want this to be true eventually. */
840 return unpack_long (type
, valaddr
);
844 /* Get the value of the FIELDN'th field (which must be static) of
845 TYPE. Return NULL if the field doesn't exist or has been
849 value_static_field (struct type
*type
, int fieldno
)
851 struct value
*retval
;
853 if (TYPE_FIELD_STATIC_HAS_ADDR (type
, fieldno
))
855 retval
= value_at (TYPE_FIELD_TYPE (type
, fieldno
),
856 TYPE_FIELD_STATIC_PHYSADDR (type
, fieldno
));
860 char *phys_name
= TYPE_FIELD_STATIC_PHYSNAME (type
, fieldno
);
861 struct symbol
*sym
= lookup_symbol (phys_name
, 0, VAR_DOMAIN
, 0, NULL
);
864 /* With some compilers, e.g. HP aCC, static data members are reported
865 as non-debuggable symbols */
866 struct minimal_symbol
*msym
= lookup_minimal_symbol (phys_name
, NULL
, NULL
);
871 retval
= value_at (TYPE_FIELD_TYPE (type
, fieldno
),
872 SYMBOL_VALUE_ADDRESS (msym
));
877 /* SYM should never have a SYMBOL_CLASS which will require
878 read_var_value to use the FRAME parameter. */
879 if (symbol_read_needs_frame (sym
))
880 warning ("static field's value depends on the current "
881 "frame - bad debug info?");
882 retval
= read_var_value (sym
, NULL
);
884 if (retval
&& VALUE_LVAL (retval
) == lval_memory
)
885 SET_FIELD_PHYSADDR (TYPE_FIELD (type
, fieldno
),
886 VALUE_ADDRESS (retval
));
891 /* Change the enclosing type of a value object VAL to NEW_ENCL_TYPE.
892 You have to be careful here, since the size of the data area for the value
893 is set by the length of the enclosing type. So if NEW_ENCL_TYPE is bigger
894 than the old enclosing type, you have to allocate more space for the data.
895 The return value is a pointer to the new version of this value structure. */
898 value_change_enclosing_type (struct value
*val
, struct type
*new_encl_type
)
900 if (TYPE_LENGTH (new_encl_type
) <= TYPE_LENGTH (value_enclosing_type (val
)))
902 val
->enclosing_type
= new_encl_type
;
907 struct value
*new_val
;
910 new_val
= (struct value
*) xrealloc (val
, sizeof (struct value
) + TYPE_LENGTH (new_encl_type
));
912 new_val
->enclosing_type
= new_encl_type
;
914 /* We have to make sure this ends up in the same place in the value
915 chain as the original copy, so it's clean-up behavior is the same.
916 If the value has been released, this is a waste of time, but there
917 is no way to tell that in advance, so... */
919 if (val
!= all_values
)
921 for (prev
= all_values
; prev
!= NULL
; prev
= prev
->next
)
923 if (prev
->next
== val
)
925 prev
->next
= new_val
;
935 /* Given a value ARG1 (offset by OFFSET bytes)
936 of a struct or union type ARG_TYPE,
937 extract and return the value of one of its (non-static) fields.
938 FIELDNO says which field. */
941 value_primitive_field (struct value
*arg1
, int offset
,
942 int fieldno
, struct type
*arg_type
)
947 CHECK_TYPEDEF (arg_type
);
948 type
= TYPE_FIELD_TYPE (arg_type
, fieldno
);
950 /* Handle packed fields */
952 if (TYPE_FIELD_BITSIZE (arg_type
, fieldno
))
954 v
= value_from_longest (type
,
955 unpack_field_as_long (arg_type
,
956 VALUE_CONTENTS (arg1
)
959 v
->bitpos
= TYPE_FIELD_BITPOS (arg_type
, fieldno
) % 8;
960 v
->bitsize
= TYPE_FIELD_BITSIZE (arg_type
, fieldno
);
961 v
->offset
= value_offset (arg1
) + offset
962 + TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
964 else if (fieldno
< TYPE_N_BASECLASSES (arg_type
))
966 /* This field is actually a base subobject, so preserve the
967 entire object's contents for later references to virtual
969 v
= allocate_value (value_enclosing_type (arg1
));
971 if (value_lazy (arg1
))
974 memcpy (value_contents_all_raw (v
), value_contents_all_raw (arg1
),
975 TYPE_LENGTH (value_enclosing_type (arg1
)));
976 v
->offset
= value_offset (arg1
);
977 VALUE_EMBEDDED_OFFSET (v
)
979 VALUE_EMBEDDED_OFFSET (arg1
) +
980 TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
984 /* Plain old data member */
985 offset
+= TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
986 v
= allocate_value (type
);
987 if (value_lazy (arg1
))
990 memcpy (value_contents_raw (v
),
991 value_contents_raw (arg1
) + offset
,
993 v
->offset
= (value_offset (arg1
) + offset
994 + VALUE_EMBEDDED_OFFSET (arg1
));
996 VALUE_LVAL (v
) = VALUE_LVAL (arg1
);
997 if (VALUE_LVAL (arg1
) == lval_internalvar
)
998 VALUE_LVAL (v
) = lval_internalvar_component
;
999 VALUE_ADDRESS (v
) = VALUE_ADDRESS (arg1
);
1000 VALUE_REGNUM (v
) = VALUE_REGNUM (arg1
);
1001 VALUE_FRAME_ID (v
) = VALUE_FRAME_ID (arg1
);
1002 /* VALUE_OFFSET (v) = VALUE_OFFSET (arg1) + offset
1003 + TYPE_FIELD_BITPOS (arg_type, fieldno) / 8; */
1007 /* Given a value ARG1 of a struct or union type,
1008 extract and return the value of one of its (non-static) fields.
1009 FIELDNO says which field. */
1012 value_field (struct value
*arg1
, int fieldno
)
1014 return value_primitive_field (arg1
, 0, fieldno
, value_type (arg1
));
1017 /* Return a non-virtual function as a value.
1018 F is the list of member functions which contains the desired method.
1019 J is an index into F which provides the desired method.
1021 We only use the symbol for its address, so be happy with either a
1022 full symbol or a minimal symbol.
1026 value_fn_field (struct value
**arg1p
, struct fn_field
*f
, int j
, struct type
*type
,
1030 struct type
*ftype
= TYPE_FN_FIELD_TYPE (f
, j
);
1031 char *physname
= TYPE_FN_FIELD_PHYSNAME (f
, j
);
1033 struct minimal_symbol
*msym
;
1035 sym
= lookup_symbol (physname
, 0, VAR_DOMAIN
, 0, NULL
);
1042 gdb_assert (sym
== NULL
);
1043 msym
= lookup_minimal_symbol (physname
, NULL
, NULL
);
1048 v
= allocate_value (ftype
);
1051 VALUE_ADDRESS (v
) = BLOCK_START (SYMBOL_BLOCK_VALUE (sym
));
1055 VALUE_ADDRESS (v
) = SYMBOL_VALUE_ADDRESS (msym
);
1060 if (type
!= value_type (*arg1p
))
1061 *arg1p
= value_ind (value_cast (lookup_pointer_type (type
),
1062 value_addr (*arg1p
)));
1064 /* Move the `this' pointer according to the offset.
1065 VALUE_OFFSET (*arg1p) += offset;
1073 /* Unpack a field FIELDNO of the specified TYPE, from the anonymous object at
1076 Extracting bits depends on endianness of the machine. Compute the
1077 number of least significant bits to discard. For big endian machines,
1078 we compute the total number of bits in the anonymous object, subtract
1079 off the bit count from the MSB of the object to the MSB of the
1080 bitfield, then the size of the bitfield, which leaves the LSB discard
1081 count. For little endian machines, the discard count is simply the
1082 number of bits from the LSB of the anonymous object to the LSB of the
1085 If the field is signed, we also do sign extension. */
1088 unpack_field_as_long (struct type
*type
, const char *valaddr
, int fieldno
)
1092 int bitpos
= TYPE_FIELD_BITPOS (type
, fieldno
);
1093 int bitsize
= TYPE_FIELD_BITSIZE (type
, fieldno
);
1095 struct type
*field_type
;
1097 val
= extract_unsigned_integer (valaddr
+ bitpos
/ 8, sizeof (val
));
1098 field_type
= TYPE_FIELD_TYPE (type
, fieldno
);
1099 CHECK_TYPEDEF (field_type
);
1101 /* Extract bits. See comment above. */
1103 if (BITS_BIG_ENDIAN
)
1104 lsbcount
= (sizeof val
* 8 - bitpos
% 8 - bitsize
);
1106 lsbcount
= (bitpos
% 8);
1109 /* If the field does not entirely fill a LONGEST, then zero the sign bits.
1110 If the field is signed, and is negative, then sign extend. */
1112 if ((bitsize
> 0) && (bitsize
< 8 * (int) sizeof (val
)))
1114 valmask
= (((ULONGEST
) 1) << bitsize
) - 1;
1116 if (!TYPE_UNSIGNED (field_type
))
1118 if (val
& (valmask
^ (valmask
>> 1)))
1127 /* Modify the value of a bitfield. ADDR points to a block of memory in
1128 target byte order; the bitfield starts in the byte pointed to. FIELDVAL
1129 is the desired value of the field, in host byte order. BITPOS and BITSIZE
1130 indicate which bits (in target bit order) comprise the bitfield.
1131 Requires 0 < BITSIZE <= lbits, 0 <= BITPOS+BITSIZE <= lbits, and
1132 0 <= BITPOS, where lbits is the size of a LONGEST in bits. */
1135 modify_field (char *addr
, LONGEST fieldval
, int bitpos
, int bitsize
)
1138 ULONGEST mask
= (ULONGEST
) -1 >> (8 * sizeof (ULONGEST
) - bitsize
);
1140 /* If a negative fieldval fits in the field in question, chop
1141 off the sign extension bits. */
1142 if ((~fieldval
& ~(mask
>> 1)) == 0)
1145 /* Warn if value is too big to fit in the field in question. */
1146 if (0 != (fieldval
& ~mask
))
1148 /* FIXME: would like to include fieldval in the message, but
1149 we don't have a sprintf_longest. */
1150 warning ("Value does not fit in %d bits.", bitsize
);
1152 /* Truncate it, otherwise adjoining fields may be corrupted. */
1156 oword
= extract_unsigned_integer (addr
, sizeof oword
);
1158 /* Shifting for bit field depends on endianness of the target machine. */
1159 if (BITS_BIG_ENDIAN
)
1160 bitpos
= sizeof (oword
) * 8 - bitpos
- bitsize
;
1162 oword
&= ~(mask
<< bitpos
);
1163 oword
|= fieldval
<< bitpos
;
1165 store_unsigned_integer (addr
, sizeof oword
, oword
);
1168 /* Convert C numbers into newly allocated values */
1171 value_from_longest (struct type
*type
, LONGEST num
)
1173 struct value
*val
= allocate_value (type
);
1174 enum type_code code
;
1177 code
= TYPE_CODE (type
);
1178 len
= TYPE_LENGTH (type
);
1182 case TYPE_CODE_TYPEDEF
:
1183 type
= check_typedef (type
);
1186 case TYPE_CODE_CHAR
:
1187 case TYPE_CODE_ENUM
:
1188 case TYPE_CODE_BOOL
:
1189 case TYPE_CODE_RANGE
:
1190 store_signed_integer (value_contents_raw (val
), len
, num
);
1195 store_typed_address (value_contents_raw (val
), type
, (CORE_ADDR
) num
);
1199 error ("Unexpected type (%d) encountered for integer constant.", code
);
1205 /* Create a value representing a pointer of type TYPE to the address
1208 value_from_pointer (struct type
*type
, CORE_ADDR addr
)
1210 struct value
*val
= allocate_value (type
);
1211 store_typed_address (value_contents_raw (val
), type
, addr
);
1216 /* Create a value for a string constant to be stored locally
1217 (not in the inferior's memory space, but in GDB memory).
1218 This is analogous to value_from_longest, which also does not
1219 use inferior memory. String shall NOT contain embedded nulls. */
1222 value_from_string (char *ptr
)
1225 int len
= strlen (ptr
);
1226 int lowbound
= current_language
->string_lower_bound
;
1227 struct type
*string_char_type
;
1228 struct type
*rangetype
;
1229 struct type
*stringtype
;
1231 rangetype
= create_range_type ((struct type
*) NULL
,
1233 lowbound
, len
+ lowbound
- 1);
1234 string_char_type
= language_string_char_type (current_language
,
1236 stringtype
= create_array_type ((struct type
*) NULL
,
1239 val
= allocate_value (stringtype
);
1240 memcpy (value_contents_raw (val
), ptr
, len
);
1245 value_from_double (struct type
*type
, DOUBLEST num
)
1247 struct value
*val
= allocate_value (type
);
1248 struct type
*base_type
= check_typedef (type
);
1249 enum type_code code
= TYPE_CODE (base_type
);
1250 int len
= TYPE_LENGTH (base_type
);
1252 if (code
== TYPE_CODE_FLT
)
1254 store_typed_floating (value_contents_raw (val
), base_type
, num
);
1257 error ("Unexpected type encountered for floating constant.");
1263 coerce_ref (struct value
*arg
)
1265 struct type
*value_type_arg_tmp
= check_typedef (value_type (arg
));
1266 if (TYPE_CODE (value_type_arg_tmp
) == TYPE_CODE_REF
)
1267 arg
= value_at_lazy (TYPE_TARGET_TYPE (value_type_arg_tmp
),
1268 unpack_pointer (value_type (arg
),
1269 VALUE_CONTENTS (arg
)));
1274 coerce_array (struct value
*arg
)
1276 arg
= coerce_ref (arg
);
1277 if (current_language
->c_style_arrays
1278 && TYPE_CODE (value_type (arg
)) == TYPE_CODE_ARRAY
)
1279 arg
= value_coerce_array (arg
);
1280 if (TYPE_CODE (value_type (arg
)) == TYPE_CODE_FUNC
)
1281 arg
= value_coerce_function (arg
);
1286 coerce_number (struct value
*arg
)
1288 arg
= coerce_array (arg
);
1289 arg
= coerce_enum (arg
);
1294 coerce_enum (struct value
*arg
)
1296 if (TYPE_CODE (check_typedef (value_type (arg
))) == TYPE_CODE_ENUM
)
1297 arg
= value_cast (builtin_type_unsigned_int
, arg
);
1302 /* Should we use DEPRECATED_EXTRACT_STRUCT_VALUE_ADDRESS instead of
1303 EXTRACT_RETURN_VALUE? GCC_P is true if compiled with gcc and TYPE
1304 is the type (which is known to be struct, union or array).
1306 On most machines, the struct convention is used unless we are
1307 using gcc and the type is of a special size. */
1308 /* As of about 31 Mar 93, GCC was changed to be compatible with the
1309 native compiler. GCC 2.3.3 was the last release that did it the
1310 old way. Since gcc2_compiled was not changed, we have no
1311 way to correctly win in all cases, so we just do the right thing
1312 for gcc1 and for gcc2 after this change. Thus it loses for gcc
1313 2.0-2.3.3. This is somewhat unfortunate, but changing gcc2_compiled
1314 would cause more chaos than dealing with some struct returns being
1316 /* NOTE: cagney/2004-06-13: Deleted check for "gcc_p". GCC 1.x is
1320 generic_use_struct_convention (int gcc_p
, struct type
*value_type
)
1322 return !(TYPE_LENGTH (value_type
) == 1
1323 || TYPE_LENGTH (value_type
) == 2
1324 || TYPE_LENGTH (value_type
) == 4
1325 || TYPE_LENGTH (value_type
) == 8);
1328 /* Return true if the function returning the specified type is using
1329 the convention of returning structures in memory (passing in the
1330 address as a hidden first parameter). GCC_P is nonzero if compiled
1334 using_struct_return (struct type
*value_type
, int gcc_p
)
1336 enum type_code code
= TYPE_CODE (value_type
);
1338 if (code
== TYPE_CODE_ERROR
)
1339 error ("Function return type unknown.");
1341 if (code
== TYPE_CODE_VOID
)
1342 /* A void return value is never in memory. See also corresponding
1343 code in "print_return_value". */
1346 /* Probe the architecture for the return-value convention. */
1347 return (gdbarch_return_value (current_gdbarch
, value_type
,
1349 != RETURN_VALUE_REGISTER_CONVENTION
);
1353 _initialize_values (void)
1355 add_cmd ("convenience", no_class
, show_convenience
,
1356 "Debugger convenience (\"$foo\") variables.\n\
1357 These variables are created when you assign them values;\n\
1358 thus, \"print $foo=1\" gives \"$foo\" the value 1. Values may be any type.\n\n\
1359 A few convenience variables are given values automatically:\n\
1360 \"$_\"holds the last address examined with \"x\" or \"info lines\",\n\
1361 \"$__\" holds the contents of the last address examined with \"x\".",
1364 add_cmd ("values", no_class
, show_values
,
1365 "Elements of value history around item number IDX (or last ten).",