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 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. */
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 VALUE_NEXT (val
) = all_values
;
89 VALUE_TYPE (val
) = type
;
90 VALUE_ENCLOSING_TYPE (val
) = type
;
91 VALUE_LVAL (val
) = not_lval
;
92 VALUE_ADDRESS (val
) = 0;
93 VALUE_FRAME_ID (val
) = null_frame_id
;
94 VALUE_OFFSET (val
) = 0;
95 VALUE_BITPOS (val
) = 0;
96 VALUE_BITSIZE (val
) = 0;
97 VALUE_REGNO (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 /* Return a mark in the value chain. All values allocated after the
125 mark is obtained (except for those released) are subject to being freed
126 if a subsequent value_free_to_mark is passed the mark. */
133 /* Free all values allocated since MARK was obtained by value_mark
134 (except for those released). */
136 value_free_to_mark (struct value
*mark
)
141 for (val
= all_values
; val
&& val
!= mark
; val
= next
)
143 next
= VALUE_NEXT (val
);
149 /* Free all the values that have been allocated (except for those released).
150 Called after each command, successful or not. */
153 free_all_values (void)
158 for (val
= all_values
; val
; val
= next
)
160 next
= VALUE_NEXT (val
);
167 /* Remove VAL from the chain all_values
168 so it will not be freed automatically. */
171 release_value (struct value
*val
)
175 if (all_values
== val
)
177 all_values
= val
->next
;
181 for (v
= all_values
; v
; v
= v
->next
)
191 /* Release all values up to mark */
193 value_release_to_mark (struct value
*mark
)
198 for (val
= next
= all_values
; next
; next
= VALUE_NEXT (next
))
199 if (VALUE_NEXT (next
) == mark
)
201 all_values
= VALUE_NEXT (next
);
202 VALUE_NEXT (next
) = 0;
209 /* Return a copy of the value ARG.
210 It contains the same contents, for same memory address,
211 but it's a different block of storage. */
214 value_copy (struct value
*arg
)
216 struct type
*encl_type
= VALUE_ENCLOSING_TYPE (arg
);
217 struct value
*val
= allocate_value (encl_type
);
218 VALUE_TYPE (val
) = VALUE_TYPE (arg
);
219 VALUE_LVAL (val
) = VALUE_LVAL (arg
);
220 VALUE_ADDRESS (val
) = VALUE_ADDRESS (arg
);
221 VALUE_OFFSET (val
) = VALUE_OFFSET (arg
);
222 VALUE_BITPOS (val
) = VALUE_BITPOS (arg
);
223 VALUE_BITSIZE (val
) = VALUE_BITSIZE (arg
);
224 VALUE_FRAME_ID (val
) = VALUE_FRAME_ID (arg
);
225 VALUE_REGNO (val
) = VALUE_REGNO (arg
);
226 VALUE_LAZY (val
) = VALUE_LAZY (arg
);
227 VALUE_OPTIMIZED_OUT (val
) = VALUE_OPTIMIZED_OUT (arg
);
228 VALUE_EMBEDDED_OFFSET (val
) = VALUE_EMBEDDED_OFFSET (arg
);
229 VALUE_POINTED_TO_OFFSET (val
) = VALUE_POINTED_TO_OFFSET (arg
);
230 val
->modifiable
= arg
->modifiable
;
231 if (!VALUE_LAZY (val
))
233 memcpy (VALUE_CONTENTS_ALL_RAW (val
), VALUE_CONTENTS_ALL_RAW (arg
),
234 TYPE_LENGTH (VALUE_ENCLOSING_TYPE (arg
)));
240 /* Access to the value history. */
242 /* Record a new value in the value history.
243 Returns the absolute history index of the entry.
244 Result of -1 indicates the value was not saved; otherwise it is the
245 value history index of this new item. */
248 record_latest_value (struct value
*val
)
252 /* We don't want this value to have anything to do with the inferior anymore.
253 In particular, "set $1 = 50" should not affect the variable from which
254 the value was taken, and fast watchpoints should be able to assume that
255 a value on the value history never changes. */
256 if (VALUE_LAZY (val
))
257 value_fetch_lazy (val
);
258 /* We preserve VALUE_LVAL so that the user can find out where it was fetched
259 from. This is a bit dubious, because then *&$1 does not just return $1
260 but the current contents of that location. c'est la vie... */
264 /* Here we treat value_history_count as origin-zero
265 and applying to the value being stored now. */
267 i
= value_history_count
% VALUE_HISTORY_CHUNK
;
270 struct value_history_chunk
*new
271 = (struct value_history_chunk
*)
272 xmalloc (sizeof (struct value_history_chunk
));
273 memset (new->values
, 0, sizeof new->values
);
274 new->next
= value_history_chain
;
275 value_history_chain
= new;
278 value_history_chain
->values
[i
] = val
;
280 /* Now we regard value_history_count as origin-one
281 and applying to the value just stored. */
283 return ++value_history_count
;
286 /* Return a copy of the value in the history with sequence number NUM. */
289 access_value_history (int num
)
291 struct value_history_chunk
*chunk
;
296 absnum
+= value_history_count
;
301 error ("The history is empty.");
303 error ("There is only one value in the history.");
305 error ("History does not go back to $$%d.", -num
);
307 if (absnum
> value_history_count
)
308 error ("History has not yet reached $%d.", absnum
);
312 /* Now absnum is always absolute and origin zero. */
314 chunk
= value_history_chain
;
315 for (i
= (value_history_count
- 1) / VALUE_HISTORY_CHUNK
- absnum
/ VALUE_HISTORY_CHUNK
;
319 return value_copy (chunk
->values
[absnum
% VALUE_HISTORY_CHUNK
]);
322 /* Clear the value history entirely.
323 Must be done when new symbol tables are loaded,
324 because the type pointers become invalid. */
327 clear_value_history (void)
329 struct value_history_chunk
*next
;
333 while (value_history_chain
)
335 for (i
= 0; i
< VALUE_HISTORY_CHUNK
; i
++)
336 if ((val
= value_history_chain
->values
[i
]) != NULL
)
338 next
= value_history_chain
->next
;
339 xfree (value_history_chain
);
340 value_history_chain
= next
;
342 value_history_count
= 0;
346 show_values (char *num_exp
, int from_tty
)
354 /* "info history +" should print from the stored position.
355 "info history <exp>" should print around value number <exp>. */
356 if (num_exp
[0] != '+' || num_exp
[1] != '\0')
357 num
= parse_and_eval_long (num_exp
) - 5;
361 /* "info history" means print the last 10 values. */
362 num
= value_history_count
- 9;
368 for (i
= num
; i
< num
+ 10 && i
<= value_history_count
; i
++)
370 val
= access_value_history (i
);
371 printf_filtered ("$%d = ", i
);
372 value_print (val
, gdb_stdout
, 0, Val_pretty_default
);
373 printf_filtered ("\n");
376 /* The next "info history +" should start after what we just printed. */
379 /* Hitting just return after this command should do the same thing as
380 "info history +". If num_exp is null, this is unnecessary, since
381 "info history +" is not useful after "info history". */
382 if (from_tty
&& num_exp
)
389 /* Internal variables. These are variables within the debugger
390 that hold values assigned by debugger commands.
391 The user refers to them with a '$' prefix
392 that does not appear in the variable names stored internally. */
394 static struct internalvar
*internalvars
;
396 /* Look up an internal variable with name NAME. NAME should not
397 normally include a dollar sign.
399 If the specified internal variable does not exist,
400 one is created, with a void value. */
403 lookup_internalvar (char *name
)
405 struct internalvar
*var
;
407 for (var
= internalvars
; var
; var
= var
->next
)
408 if (strcmp (var
->name
, name
) == 0)
411 var
= (struct internalvar
*) xmalloc (sizeof (struct internalvar
));
412 var
->name
= concat (name
, NULL
);
413 var
->value
= allocate_value (builtin_type_void
);
414 release_value (var
->value
);
415 var
->next
= internalvars
;
421 value_of_internalvar (struct internalvar
*var
)
425 val
= value_copy (var
->value
);
426 if (VALUE_LAZY (val
))
427 value_fetch_lazy (val
);
428 VALUE_LVAL (val
) = lval_internalvar
;
429 VALUE_INTERNALVAR (val
) = var
;
434 set_internalvar_component (struct internalvar
*var
, int offset
, int bitpos
,
435 int bitsize
, struct value
*newval
)
437 char *addr
= VALUE_CONTENTS (var
->value
) + offset
;
440 modify_field (addr
, value_as_long (newval
),
443 memcpy (addr
, VALUE_CONTENTS (newval
), TYPE_LENGTH (VALUE_TYPE (newval
)));
447 set_internalvar (struct internalvar
*var
, struct value
*val
)
449 struct value
*newval
;
451 newval
= value_copy (val
);
452 newval
->modifiable
= 1;
454 /* Force the value to be fetched from the target now, to avoid problems
455 later when this internalvar is referenced and the target is gone or
457 if (VALUE_LAZY (newval
))
458 value_fetch_lazy (newval
);
460 /* Begin code which must not call error(). If var->value points to
461 something free'd, an error() obviously leaves a dangling pointer.
462 But we also get a danling pointer if var->value points to
463 something in the value chain (i.e., before release_value is
464 called), because after the error free_all_values will get called before
468 release_value (newval
);
469 /* End code which must not call error(). */
473 internalvar_name (struct internalvar
*var
)
478 /* Free all internalvars. Done when new symtabs are loaded,
479 because that makes the values invalid. */
482 clear_internalvars (void)
484 struct internalvar
*var
;
489 internalvars
= var
->next
;
497 show_convenience (char *ignore
, int from_tty
)
499 struct internalvar
*var
;
502 for (var
= internalvars
; var
; var
= var
->next
)
508 printf_filtered ("$%s = ", var
->name
);
509 value_print (var
->value
, gdb_stdout
, 0, Val_pretty_default
);
510 printf_filtered ("\n");
513 printf_unfiltered ("No debugger convenience variables now defined.\n\
514 Convenience variables have names starting with \"$\";\n\
515 use \"set\" as in \"set $foo = 5\" to define them.\n");
518 /* Extract a value as a C number (either long or double).
519 Knows how to convert fixed values to double, or
520 floating values to long.
521 Does not deallocate the value. */
524 value_as_long (struct value
*val
)
526 /* This coerces arrays and functions, which is necessary (e.g.
527 in disassemble_command). It also dereferences references, which
528 I suspect is the most logical thing to do. */
530 return unpack_long (VALUE_TYPE (val
), VALUE_CONTENTS (val
));
534 value_as_double (struct value
*val
)
539 foo
= unpack_double (VALUE_TYPE (val
), VALUE_CONTENTS (val
), &inv
);
541 error ("Invalid floating value found in program.");
544 /* Extract a value as a C pointer. Does not deallocate the value.
545 Note that val's type may not actually be a pointer; value_as_long
546 handles all the cases. */
548 value_as_address (struct value
*val
)
550 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
551 whether we want this to be true eventually. */
553 /* ADDR_BITS_REMOVE is wrong if we are being called for a
554 non-address (e.g. argument to "signal", "info break", etc.), or
555 for pointers to char, in which the low bits *are* significant. */
556 return ADDR_BITS_REMOVE (value_as_long (val
));
559 /* There are several targets (IA-64, PowerPC, and others) which
560 don't represent pointers to functions as simply the address of
561 the function's entry point. For example, on the IA-64, a
562 function pointer points to a two-word descriptor, generated by
563 the linker, which contains the function's entry point, and the
564 value the IA-64 "global pointer" register should have --- to
565 support position-independent code. The linker generates
566 descriptors only for those functions whose addresses are taken.
568 On such targets, it's difficult for GDB to convert an arbitrary
569 function address into a function pointer; it has to either find
570 an existing descriptor for that function, or call malloc and
571 build its own. On some targets, it is impossible for GDB to
572 build a descriptor at all: the descriptor must contain a jump
573 instruction; data memory cannot be executed; and code memory
576 Upon entry to this function, if VAL is a value of type `function'
577 (that is, TYPE_CODE (VALUE_TYPE (val)) == TYPE_CODE_FUNC), then
578 VALUE_ADDRESS (val) is the address of the function. This is what
579 you'll get if you evaluate an expression like `main'. The call
580 to COERCE_ARRAY below actually does all the usual unary
581 conversions, which includes converting values of type `function'
582 to `pointer to function'. This is the challenging conversion
583 discussed above. Then, `unpack_long' will convert that pointer
584 back into an address.
586 So, suppose the user types `disassemble foo' on an architecture
587 with a strange function pointer representation, on which GDB
588 cannot build its own descriptors, and suppose further that `foo'
589 has no linker-built descriptor. The address->pointer conversion
590 will signal an error and prevent the command from running, even
591 though the next step would have been to convert the pointer
592 directly back into the same address.
594 The following shortcut avoids this whole mess. If VAL is a
595 function, just return its address directly. */
596 if (TYPE_CODE (VALUE_TYPE (val
)) == TYPE_CODE_FUNC
597 || TYPE_CODE (VALUE_TYPE (val
)) == TYPE_CODE_METHOD
)
598 return VALUE_ADDRESS (val
);
602 /* Some architectures (e.g. Harvard), map instruction and data
603 addresses onto a single large unified address space. For
604 instance: An architecture may consider a large integer in the
605 range 0x10000000 .. 0x1000ffff to already represent a data
606 addresses (hence not need a pointer to address conversion) while
607 a small integer would still need to be converted integer to
608 pointer to address. Just assume such architectures handle all
609 integer conversions in a single function. */
613 I think INTEGER_TO_ADDRESS is a good idea as proposed --- but we
614 must admonish GDB hackers to make sure its behavior matches the
615 compiler's, whenever possible.
617 In general, I think GDB should evaluate expressions the same way
618 the compiler does. When the user copies an expression out of
619 their source code and hands it to a `print' command, they should
620 get the same value the compiler would have computed. Any
621 deviation from this rule can cause major confusion and annoyance,
622 and needs to be justified carefully. In other words, GDB doesn't
623 really have the freedom to do these conversions in clever and
626 AndrewC pointed out that users aren't complaining about how GDB
627 casts integers to pointers; they are complaining that they can't
628 take an address from a disassembly listing and give it to `x/i'.
629 This is certainly important.
631 Adding an architecture method like INTEGER_TO_ADDRESS certainly
632 makes it possible for GDB to "get it right" in all circumstances
633 --- the target has complete control over how things get done, so
634 people can Do The Right Thing for their target without breaking
635 anyone else. The standard doesn't specify how integers get
636 converted to pointers; usually, the ABI doesn't either, but
637 ABI-specific code is a more reasonable place to handle it. */
639 if (TYPE_CODE (VALUE_TYPE (val
)) != TYPE_CODE_PTR
640 && TYPE_CODE (VALUE_TYPE (val
)) != TYPE_CODE_REF
641 && INTEGER_TO_ADDRESS_P ())
642 return INTEGER_TO_ADDRESS (VALUE_TYPE (val
), VALUE_CONTENTS (val
));
644 return unpack_long (VALUE_TYPE (val
), VALUE_CONTENTS (val
));
648 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
649 as a long, or as a double, assuming the raw data is described
650 by type TYPE. Knows how to convert different sizes of values
651 and can convert between fixed and floating point. We don't assume
652 any alignment for the raw data. Return value is in host byte order.
654 If you want functions and arrays to be coerced to pointers, and
655 references to be dereferenced, call value_as_long() instead.
657 C++: It is assumed that the front-end has taken care of
658 all matters concerning pointers to members. A pointer
659 to member which reaches here is considered to be equivalent
660 to an INT (or some size). After all, it is only an offset. */
663 unpack_long (struct type
*type
, const char *valaddr
)
665 enum type_code code
= TYPE_CODE (type
);
666 int len
= TYPE_LENGTH (type
);
667 int nosign
= TYPE_UNSIGNED (type
);
669 if (current_language
->la_language
== language_scm
670 && is_scmvalue_type (type
))
671 return scm_unpack (type
, valaddr
, TYPE_CODE_INT
);
675 case TYPE_CODE_TYPEDEF
:
676 return unpack_long (check_typedef (type
), valaddr
);
681 case TYPE_CODE_RANGE
:
683 return extract_unsigned_integer (valaddr
, len
);
685 return extract_signed_integer (valaddr
, len
);
688 return extract_typed_floating (valaddr
, type
);
692 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
693 whether we want this to be true eventually. */
694 return extract_typed_address (valaddr
, type
);
696 case TYPE_CODE_MEMBER
:
697 error ("not implemented: member types in unpack_long");
700 error ("Value can't be converted to integer.");
702 return 0; /* Placate lint. */
705 /* Return a double value from the specified type and address.
706 INVP points to an int which is set to 0 for valid value,
707 1 for invalid value (bad float format). In either case,
708 the returned double is OK to use. Argument is in target
709 format, result is in host format. */
712 unpack_double (struct type
*type
, const char *valaddr
, int *invp
)
718 *invp
= 0; /* Assume valid. */
719 CHECK_TYPEDEF (type
);
720 code
= TYPE_CODE (type
);
721 len
= TYPE_LENGTH (type
);
722 nosign
= TYPE_UNSIGNED (type
);
723 if (code
== TYPE_CODE_FLT
)
725 /* NOTE: cagney/2002-02-19: There was a test here to see if the
726 floating-point value was valid (using the macro
727 INVALID_FLOAT). That test/macro have been removed.
729 It turns out that only the VAX defined this macro and then
730 only in a non-portable way. Fixing the portability problem
731 wouldn't help since the VAX floating-point code is also badly
732 bit-rotten. The target needs to add definitions for the
733 methods TARGET_FLOAT_FORMAT and TARGET_DOUBLE_FORMAT - these
734 exactly describe the target floating-point format. The
735 problem here is that the corresponding floatformat_vax_f and
736 floatformat_vax_d values these methods should be set to are
737 also not defined either. Oops!
739 Hopefully someone will add both the missing floatformat
740 definitions and the new cases for floatformat_is_valid (). */
742 if (!floatformat_is_valid (floatformat_from_type (type
), valaddr
))
748 return extract_typed_floating (valaddr
, type
);
752 /* Unsigned -- be sure we compensate for signed LONGEST. */
753 return (ULONGEST
) unpack_long (type
, valaddr
);
757 /* Signed -- we are OK with unpack_long. */
758 return unpack_long (type
, valaddr
);
762 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
763 as a CORE_ADDR, assuming the raw data is described by type TYPE.
764 We don't assume any alignment for the raw data. Return value is in
767 If you want functions and arrays to be coerced to pointers, and
768 references to be dereferenced, call value_as_address() instead.
770 C++: It is assumed that the front-end has taken care of
771 all matters concerning pointers to members. A pointer
772 to member which reaches here is considered to be equivalent
773 to an INT (or some size). After all, it is only an offset. */
776 unpack_pointer (struct type
*type
, const char *valaddr
)
778 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
779 whether we want this to be true eventually. */
780 return unpack_long (type
, valaddr
);
784 /* Get the value of the FIELDN'th field (which must be static) of
785 TYPE. Return NULL if the field doesn't exist or has been
789 value_static_field (struct type
*type
, int fieldno
)
791 struct value
*retval
;
793 if (TYPE_FIELD_STATIC_HAS_ADDR (type
, fieldno
))
795 retval
= value_at (TYPE_FIELD_TYPE (type
, fieldno
),
796 TYPE_FIELD_STATIC_PHYSADDR (type
, fieldno
));
800 char *phys_name
= TYPE_FIELD_STATIC_PHYSNAME (type
, fieldno
);
801 struct symbol
*sym
= lookup_symbol (phys_name
, 0, VAR_DOMAIN
, 0, NULL
);
804 /* With some compilers, e.g. HP aCC, static data members are reported
805 as non-debuggable symbols */
806 struct minimal_symbol
*msym
= lookup_minimal_symbol (phys_name
, NULL
, NULL
);
811 retval
= value_at (TYPE_FIELD_TYPE (type
, fieldno
),
812 SYMBOL_VALUE_ADDRESS (msym
));
817 /* SYM should never have a SYMBOL_CLASS which will require
818 read_var_value to use the FRAME parameter. */
819 if (symbol_read_needs_frame (sym
))
820 warning ("static field's value depends on the current "
821 "frame - bad debug info?");
822 retval
= read_var_value (sym
, NULL
);
824 if (retval
&& VALUE_LVAL (retval
) == lval_memory
)
825 SET_FIELD_PHYSADDR (TYPE_FIELD (type
, fieldno
),
826 VALUE_ADDRESS (retval
));
831 /* Change the enclosing type of a value object VAL to NEW_ENCL_TYPE.
832 You have to be careful here, since the size of the data area for the value
833 is set by the length of the enclosing type. So if NEW_ENCL_TYPE is bigger
834 than the old enclosing type, you have to allocate more space for the data.
835 The return value is a pointer to the new version of this value structure. */
838 value_change_enclosing_type (struct value
*val
, struct type
*new_encl_type
)
840 if (TYPE_LENGTH (new_encl_type
) <= TYPE_LENGTH (VALUE_ENCLOSING_TYPE (val
)))
842 VALUE_ENCLOSING_TYPE (val
) = new_encl_type
;
847 struct value
*new_val
;
850 new_val
= (struct value
*) xrealloc (val
, sizeof (struct value
) + TYPE_LENGTH (new_encl_type
));
852 VALUE_ENCLOSING_TYPE (new_val
) = new_encl_type
;
854 /* We have to make sure this ends up in the same place in the value
855 chain as the original copy, so it's clean-up behavior is the same.
856 If the value has been released, this is a waste of time, but there
857 is no way to tell that in advance, so... */
859 if (val
!= all_values
)
861 for (prev
= all_values
; prev
!= NULL
; prev
= prev
->next
)
863 if (prev
->next
== val
)
865 prev
->next
= new_val
;
875 /* Given a value ARG1 (offset by OFFSET bytes)
876 of a struct or union type ARG_TYPE,
877 extract and return the value of one of its (non-static) fields.
878 FIELDNO says which field. */
881 value_primitive_field (struct value
*arg1
, int offset
,
882 int fieldno
, struct type
*arg_type
)
887 CHECK_TYPEDEF (arg_type
);
888 type
= TYPE_FIELD_TYPE (arg_type
, fieldno
);
890 /* Handle packed fields */
892 if (TYPE_FIELD_BITSIZE (arg_type
, fieldno
))
894 v
= value_from_longest (type
,
895 unpack_field_as_long (arg_type
,
896 VALUE_CONTENTS (arg1
)
899 VALUE_BITPOS (v
) = TYPE_FIELD_BITPOS (arg_type
, fieldno
) % 8;
900 VALUE_BITSIZE (v
) = TYPE_FIELD_BITSIZE (arg_type
, fieldno
);
901 VALUE_OFFSET (v
) = VALUE_OFFSET (arg1
) + offset
902 + TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
904 else if (fieldno
< TYPE_N_BASECLASSES (arg_type
))
906 /* This field is actually a base subobject, so preserve the
907 entire object's contents for later references to virtual
909 v
= allocate_value (VALUE_ENCLOSING_TYPE (arg1
));
910 VALUE_TYPE (v
) = type
;
911 if (VALUE_LAZY (arg1
))
914 memcpy (VALUE_CONTENTS_ALL_RAW (v
), VALUE_CONTENTS_ALL_RAW (arg1
),
915 TYPE_LENGTH (VALUE_ENCLOSING_TYPE (arg1
)));
916 VALUE_OFFSET (v
) = VALUE_OFFSET (arg1
);
917 VALUE_EMBEDDED_OFFSET (v
)
919 VALUE_EMBEDDED_OFFSET (arg1
) +
920 TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
924 /* Plain old data member */
925 offset
+= TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
926 v
= allocate_value (type
);
927 if (VALUE_LAZY (arg1
))
930 memcpy (VALUE_CONTENTS_RAW (v
),
931 VALUE_CONTENTS_RAW (arg1
) + offset
,
933 VALUE_OFFSET (v
) = VALUE_OFFSET (arg1
) + offset
934 + VALUE_EMBEDDED_OFFSET (arg1
);
936 VALUE_LVAL (v
) = VALUE_LVAL (arg1
);
937 if (VALUE_LVAL (arg1
) == lval_internalvar
)
938 VALUE_LVAL (v
) = lval_internalvar_component
;
939 VALUE_ADDRESS (v
) = VALUE_ADDRESS (arg1
);
940 VALUE_REGNO (v
) = VALUE_REGNO (arg1
);
941 /* VALUE_OFFSET (v) = VALUE_OFFSET (arg1) + offset
942 + TYPE_FIELD_BITPOS (arg_type, fieldno) / 8; */
946 /* Given a value ARG1 of a struct or union type,
947 extract and return the value of one of its (non-static) fields.
948 FIELDNO says which field. */
951 value_field (struct value
*arg1
, int fieldno
)
953 return value_primitive_field (arg1
, 0, fieldno
, VALUE_TYPE (arg1
));
956 /* Return a non-virtual function as a value.
957 F is the list of member functions which contains the desired method.
958 J is an index into F which provides the desired method.
960 We only use the symbol for its address, so be happy with either a
961 full symbol or a minimal symbol.
965 value_fn_field (struct value
**arg1p
, struct fn_field
*f
, int j
, struct type
*type
,
969 struct type
*ftype
= TYPE_FN_FIELD_TYPE (f
, j
);
970 char *physname
= TYPE_FN_FIELD_PHYSNAME (f
, j
);
972 struct minimal_symbol
*msym
;
974 sym
= lookup_symbol (physname
, 0, VAR_DOMAIN
, 0, NULL
);
981 gdb_assert (sym
== NULL
);
982 msym
= lookup_minimal_symbol (physname
, NULL
, NULL
);
987 v
= allocate_value (ftype
);
990 VALUE_ADDRESS (v
) = BLOCK_START (SYMBOL_BLOCK_VALUE (sym
));
994 VALUE_ADDRESS (v
) = SYMBOL_VALUE_ADDRESS (msym
);
999 if (type
!= VALUE_TYPE (*arg1p
))
1000 *arg1p
= value_ind (value_cast (lookup_pointer_type (type
),
1001 value_addr (*arg1p
)));
1003 /* Move the `this' pointer according to the offset.
1004 VALUE_OFFSET (*arg1p) += offset;
1012 /* Unpack a field FIELDNO of the specified TYPE, from the anonymous object at
1015 Extracting bits depends on endianness of the machine. Compute the
1016 number of least significant bits to discard. For big endian machines,
1017 we compute the total number of bits in the anonymous object, subtract
1018 off the bit count from the MSB of the object to the MSB of the
1019 bitfield, then the size of the bitfield, which leaves the LSB discard
1020 count. For little endian machines, the discard count is simply the
1021 number of bits from the LSB of the anonymous object to the LSB of the
1024 If the field is signed, we also do sign extension. */
1027 unpack_field_as_long (struct type
*type
, const char *valaddr
, int fieldno
)
1031 int bitpos
= TYPE_FIELD_BITPOS (type
, fieldno
);
1032 int bitsize
= TYPE_FIELD_BITSIZE (type
, fieldno
);
1034 struct type
*field_type
;
1036 val
= extract_unsigned_integer (valaddr
+ bitpos
/ 8, sizeof (val
));
1037 field_type
= TYPE_FIELD_TYPE (type
, fieldno
);
1038 CHECK_TYPEDEF (field_type
);
1040 /* Extract bits. See comment above. */
1042 if (BITS_BIG_ENDIAN
)
1043 lsbcount
= (sizeof val
* 8 - bitpos
% 8 - bitsize
);
1045 lsbcount
= (bitpos
% 8);
1048 /* If the field does not entirely fill a LONGEST, then zero the sign bits.
1049 If the field is signed, and is negative, then sign extend. */
1051 if ((bitsize
> 0) && (bitsize
< 8 * (int) sizeof (val
)))
1053 valmask
= (((ULONGEST
) 1) << bitsize
) - 1;
1055 if (!TYPE_UNSIGNED (field_type
))
1057 if (val
& (valmask
^ (valmask
>> 1)))
1066 /* Modify the value of a bitfield. ADDR points to a block of memory in
1067 target byte order; the bitfield starts in the byte pointed to. FIELDVAL
1068 is the desired value of the field, in host byte order. BITPOS and BITSIZE
1069 indicate which bits (in target bit order) comprise the bitfield.
1070 Requires 0 < BITSIZE <= lbits, 0 <= BITPOS+BITSIZE <= lbits, and
1071 0 <= BITPOS, where lbits is the size of a LONGEST in bits. */
1074 modify_field (char *addr
, LONGEST fieldval
, int bitpos
, int bitsize
)
1077 ULONGEST mask
= (ULONGEST
) -1 >> (8 * sizeof (ULONGEST
) - bitsize
);
1079 /* If a negative fieldval fits in the field in question, chop
1080 off the sign extension bits. */
1081 if ((~fieldval
& ~(mask
>> 1)) == 0)
1084 /* Warn if value is too big to fit in the field in question. */
1085 if (0 != (fieldval
& ~mask
))
1087 /* FIXME: would like to include fieldval in the message, but
1088 we don't have a sprintf_longest. */
1089 warning ("Value does not fit in %d bits.", bitsize
);
1091 /* Truncate it, otherwise adjoining fields may be corrupted. */
1095 oword
= extract_unsigned_integer (addr
, sizeof oword
);
1097 /* Shifting for bit field depends on endianness of the target machine. */
1098 if (BITS_BIG_ENDIAN
)
1099 bitpos
= sizeof (oword
) * 8 - bitpos
- bitsize
;
1101 oword
&= ~(mask
<< bitpos
);
1102 oword
|= fieldval
<< bitpos
;
1104 store_unsigned_integer (addr
, sizeof oword
, oword
);
1107 /* Convert C numbers into newly allocated values */
1110 value_from_longest (struct type
*type
, LONGEST num
)
1112 struct value
*val
= allocate_value (type
);
1113 enum type_code code
;
1116 code
= TYPE_CODE (type
);
1117 len
= TYPE_LENGTH (type
);
1121 case TYPE_CODE_TYPEDEF
:
1122 type
= check_typedef (type
);
1125 case TYPE_CODE_CHAR
:
1126 case TYPE_CODE_ENUM
:
1127 case TYPE_CODE_BOOL
:
1128 case TYPE_CODE_RANGE
:
1129 store_signed_integer (VALUE_CONTENTS_RAW (val
), len
, num
);
1134 store_typed_address (VALUE_CONTENTS_RAW (val
), type
, (CORE_ADDR
) num
);
1138 error ("Unexpected type (%d) encountered for integer constant.", code
);
1144 /* Create a value representing a pointer of type TYPE to the address
1147 value_from_pointer (struct type
*type
, CORE_ADDR addr
)
1149 struct value
*val
= allocate_value (type
);
1150 store_typed_address (VALUE_CONTENTS_RAW (val
), type
, addr
);
1155 /* Create a value for a string constant to be stored locally
1156 (not in the inferior's memory space, but in GDB memory).
1157 This is analogous to value_from_longest, which also does not
1158 use inferior memory. String shall NOT contain embedded nulls. */
1161 value_from_string (char *ptr
)
1164 int len
= strlen (ptr
);
1165 int lowbound
= current_language
->string_lower_bound
;
1166 struct type
*string_char_type
;
1167 struct type
*rangetype
;
1168 struct type
*stringtype
;
1170 rangetype
= create_range_type ((struct type
*) NULL
,
1172 lowbound
, len
+ lowbound
- 1);
1173 string_char_type
= language_string_char_type (current_language
,
1175 stringtype
= create_array_type ((struct type
*) NULL
,
1178 val
= allocate_value (stringtype
);
1179 memcpy (VALUE_CONTENTS_RAW (val
), ptr
, len
);
1184 value_from_double (struct type
*type
, DOUBLEST num
)
1186 struct value
*val
= allocate_value (type
);
1187 struct type
*base_type
= check_typedef (type
);
1188 enum type_code code
= TYPE_CODE (base_type
);
1189 int len
= TYPE_LENGTH (base_type
);
1191 if (code
== TYPE_CODE_FLT
)
1193 store_typed_floating (VALUE_CONTENTS_RAW (val
), base_type
, num
);
1196 error ("Unexpected type encountered for floating constant.");
1202 /* Should we use DEPRECATED_EXTRACT_STRUCT_VALUE_ADDRESS instead of
1203 EXTRACT_RETURN_VALUE? GCC_P is true if compiled with gcc and TYPE
1204 is the type (which is known to be struct, union or array).
1206 On most machines, the struct convention is used unless we are
1207 using gcc and the type is of a special size. */
1208 /* As of about 31 Mar 93, GCC was changed to be compatible with the
1209 native compiler. GCC 2.3.3 was the last release that did it the
1210 old way. Since gcc2_compiled was not changed, we have no
1211 way to correctly win in all cases, so we just do the right thing
1212 for gcc1 and for gcc2 after this change. Thus it loses for gcc
1213 2.0-2.3.3. This is somewhat unfortunate, but changing gcc2_compiled
1214 would cause more chaos than dealing with some struct returns being
1216 /* NOTE: cagney/2004-06-13: Deleted check for "gcc_p". GCC 1.x is
1220 generic_use_struct_convention (int gcc_p
, struct type
*value_type
)
1222 return !(TYPE_LENGTH (value_type
) == 1
1223 || TYPE_LENGTH (value_type
) == 2
1224 || TYPE_LENGTH (value_type
) == 4
1225 || TYPE_LENGTH (value_type
) == 8);
1228 /* Return true if the function returning the specified type is using
1229 the convention of returning structures in memory (passing in the
1230 address as a hidden first parameter). GCC_P is nonzero if compiled
1234 using_struct_return (struct type
*value_type
, int gcc_p
)
1236 enum type_code code
= TYPE_CODE (value_type
);
1238 if (code
== TYPE_CODE_ERROR
)
1239 error ("Function return type unknown.");
1241 if (code
== TYPE_CODE_VOID
)
1242 /* A void return value is never in memory. See also corresponding
1243 code in "print_return_value". */
1246 /* Probe the architecture for the return-value convention. */
1247 return (gdbarch_return_value (current_gdbarch
, value_type
,
1249 != RETURN_VALUE_REGISTER_CONVENTION
);
1253 _initialize_values (void)
1255 add_cmd ("convenience", no_class
, show_convenience
,
1256 "Debugger convenience (\"$foo\") variables.\n\
1257 These variables are created when you assign them values;\n\
1258 thus, \"print $foo=1\" gives \"$foo\" the value 1. Values may be any type.\n\n\
1259 A few convenience variables are given values automatically:\n\
1260 \"$_\"holds the last address examined with \"x\" or \"info lines\",\n\
1261 \"$__\" holds the contents of the last address examined with \"x\".",
1264 add_cmd ("values", no_class
, show_values
,
1265 "Elements of value history around item number IDX (or last ten).",