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 /* Return a mark in the value chain. All values allocated after the
170 mark is obtained (except for those released) are subject to being freed
171 if a subsequent value_free_to_mark is passed the mark. */
178 /* Free all values allocated since MARK was obtained by value_mark
179 (except for those released). */
181 value_free_to_mark (struct value
*mark
)
186 for (val
= all_values
; val
&& val
!= mark
; val
= next
)
194 /* Free all the values that have been allocated (except for those released).
195 Called after each command, successful or not. */
198 free_all_values (void)
203 for (val
= all_values
; val
; val
= next
)
212 /* Remove VAL from the chain all_values
213 so it will not be freed automatically. */
216 release_value (struct value
*val
)
220 if (all_values
== val
)
222 all_values
= val
->next
;
226 for (v
= all_values
; v
; v
= v
->next
)
236 /* Release all values up to mark */
238 value_release_to_mark (struct value
*mark
)
243 for (val
= next
= all_values
; next
; next
= next
->next
)
244 if (next
->next
== mark
)
246 all_values
= next
->next
;
254 /* Return a copy of the value ARG.
255 It contains the same contents, for same memory address,
256 but it's a different block of storage. */
259 value_copy (struct value
*arg
)
261 struct type
*encl_type
= value_enclosing_type (arg
);
262 struct value
*val
= allocate_value (encl_type
);
263 val
->type
= arg
->type
;
264 VALUE_LVAL (val
) = VALUE_LVAL (arg
);
265 VALUE_ADDRESS (val
) = VALUE_ADDRESS (arg
);
266 val
->offset
= arg
->offset
;
267 val
->bitpos
= arg
->bitpos
;
268 val
->bitsize
= arg
->bitsize
;
269 VALUE_FRAME_ID (val
) = VALUE_FRAME_ID (arg
);
270 VALUE_REGNUM (val
) = VALUE_REGNUM (arg
);
271 VALUE_LAZY (val
) = VALUE_LAZY (arg
);
272 VALUE_OPTIMIZED_OUT (val
) = VALUE_OPTIMIZED_OUT (arg
);
273 VALUE_EMBEDDED_OFFSET (val
) = VALUE_EMBEDDED_OFFSET (arg
);
274 VALUE_POINTED_TO_OFFSET (val
) = VALUE_POINTED_TO_OFFSET (arg
);
275 val
->modifiable
= arg
->modifiable
;
276 if (!VALUE_LAZY (val
))
278 memcpy (value_contents_all_raw (val
), value_contents_all_raw (arg
),
279 TYPE_LENGTH (value_enclosing_type (arg
)));
285 /* Access to the value history. */
287 /* Record a new value in the value history.
288 Returns the absolute history index of the entry.
289 Result of -1 indicates the value was not saved; otherwise it is the
290 value history index of this new item. */
293 record_latest_value (struct value
*val
)
297 /* We don't want this value to have anything to do with the inferior anymore.
298 In particular, "set $1 = 50" should not affect the variable from which
299 the value was taken, and fast watchpoints should be able to assume that
300 a value on the value history never changes. */
301 if (VALUE_LAZY (val
))
302 value_fetch_lazy (val
);
303 /* We preserve VALUE_LVAL so that the user can find out where it was fetched
304 from. This is a bit dubious, because then *&$1 does not just return $1
305 but the current contents of that location. c'est la vie... */
309 /* Here we treat value_history_count as origin-zero
310 and applying to the value being stored now. */
312 i
= value_history_count
% VALUE_HISTORY_CHUNK
;
315 struct value_history_chunk
*new
316 = (struct value_history_chunk
*)
317 xmalloc (sizeof (struct value_history_chunk
));
318 memset (new->values
, 0, sizeof new->values
);
319 new->next
= value_history_chain
;
320 value_history_chain
= new;
323 value_history_chain
->values
[i
] = val
;
325 /* Now we regard value_history_count as origin-one
326 and applying to the value just stored. */
328 return ++value_history_count
;
331 /* Return a copy of the value in the history with sequence number NUM. */
334 access_value_history (int num
)
336 struct value_history_chunk
*chunk
;
341 absnum
+= value_history_count
;
346 error ("The history is empty.");
348 error ("There is only one value in the history.");
350 error ("History does not go back to $$%d.", -num
);
352 if (absnum
> value_history_count
)
353 error ("History has not yet reached $%d.", absnum
);
357 /* Now absnum is always absolute and origin zero. */
359 chunk
= value_history_chain
;
360 for (i
= (value_history_count
- 1) / VALUE_HISTORY_CHUNK
- absnum
/ VALUE_HISTORY_CHUNK
;
364 return value_copy (chunk
->values
[absnum
% VALUE_HISTORY_CHUNK
]);
367 /* Clear the value history entirely.
368 Must be done when new symbol tables are loaded,
369 because the type pointers become invalid. */
372 clear_value_history (void)
374 struct value_history_chunk
*next
;
378 while (value_history_chain
)
380 for (i
= 0; i
< VALUE_HISTORY_CHUNK
; i
++)
381 if ((val
= value_history_chain
->values
[i
]) != NULL
)
383 next
= value_history_chain
->next
;
384 xfree (value_history_chain
);
385 value_history_chain
= next
;
387 value_history_count
= 0;
391 show_values (char *num_exp
, int from_tty
)
399 /* "info history +" should print from the stored position.
400 "info history <exp>" should print around value number <exp>. */
401 if (num_exp
[0] != '+' || num_exp
[1] != '\0')
402 num
= parse_and_eval_long (num_exp
) - 5;
406 /* "info history" means print the last 10 values. */
407 num
= value_history_count
- 9;
413 for (i
= num
; i
< num
+ 10 && i
<= value_history_count
; i
++)
415 val
= access_value_history (i
);
416 printf_filtered ("$%d = ", i
);
417 value_print (val
, gdb_stdout
, 0, Val_pretty_default
);
418 printf_filtered ("\n");
421 /* The next "info history +" should start after what we just printed. */
424 /* Hitting just return after this command should do the same thing as
425 "info history +". If num_exp is null, this is unnecessary, since
426 "info history +" is not useful after "info history". */
427 if (from_tty
&& num_exp
)
434 /* Internal variables. These are variables within the debugger
435 that hold values assigned by debugger commands.
436 The user refers to them with a '$' prefix
437 that does not appear in the variable names stored internally. */
439 static struct internalvar
*internalvars
;
441 /* Look up an internal variable with name NAME. NAME should not
442 normally include a dollar sign.
444 If the specified internal variable does not exist,
445 one is created, with a void value. */
448 lookup_internalvar (char *name
)
450 struct internalvar
*var
;
452 for (var
= internalvars
; var
; var
= var
->next
)
453 if (strcmp (var
->name
, name
) == 0)
456 var
= (struct internalvar
*) xmalloc (sizeof (struct internalvar
));
457 var
->name
= concat (name
, NULL
);
458 var
->value
= allocate_value (builtin_type_void
);
459 release_value (var
->value
);
460 var
->next
= internalvars
;
466 value_of_internalvar (struct internalvar
*var
)
470 val
= value_copy (var
->value
);
471 if (VALUE_LAZY (val
))
472 value_fetch_lazy (val
);
473 VALUE_LVAL (val
) = lval_internalvar
;
474 VALUE_INTERNALVAR (val
) = var
;
479 set_internalvar_component (struct internalvar
*var
, int offset
, int bitpos
,
480 int bitsize
, struct value
*newval
)
482 char *addr
= VALUE_CONTENTS (var
->value
) + offset
;
485 modify_field (addr
, value_as_long (newval
),
488 memcpy (addr
, VALUE_CONTENTS (newval
), TYPE_LENGTH (value_type (newval
)));
492 set_internalvar (struct internalvar
*var
, struct value
*val
)
494 struct value
*newval
;
496 newval
= value_copy (val
);
497 newval
->modifiable
= 1;
499 /* Force the value to be fetched from the target now, to avoid problems
500 later when this internalvar is referenced and the target is gone or
502 if (VALUE_LAZY (newval
))
503 value_fetch_lazy (newval
);
505 /* Begin code which must not call error(). If var->value points to
506 something free'd, an error() obviously leaves a dangling pointer.
507 But we also get a danling pointer if var->value points to
508 something in the value chain (i.e., before release_value is
509 called), because after the error free_all_values will get called before
513 release_value (newval
);
514 /* End code which must not call error(). */
518 internalvar_name (struct internalvar
*var
)
523 /* Free all internalvars. Done when new symtabs are loaded,
524 because that makes the values invalid. */
527 clear_internalvars (void)
529 struct internalvar
*var
;
534 internalvars
= var
->next
;
542 show_convenience (char *ignore
, int from_tty
)
544 struct internalvar
*var
;
547 for (var
= internalvars
; var
; var
= var
->next
)
553 printf_filtered ("$%s = ", var
->name
);
554 value_print (var
->value
, gdb_stdout
, 0, Val_pretty_default
);
555 printf_filtered ("\n");
558 printf_unfiltered ("No debugger convenience variables now defined.\n\
559 Convenience variables have names starting with \"$\";\n\
560 use \"set\" as in \"set $foo = 5\" to define them.\n");
563 /* Extract a value as a C number (either long or double).
564 Knows how to convert fixed values to double, or
565 floating values to long.
566 Does not deallocate the value. */
569 value_as_long (struct value
*val
)
571 /* This coerces arrays and functions, which is necessary (e.g.
572 in disassemble_command). It also dereferences references, which
573 I suspect is the most logical thing to do. */
574 val
= coerce_array (val
);
575 return unpack_long (value_type (val
), VALUE_CONTENTS (val
));
579 value_as_double (struct value
*val
)
584 foo
= unpack_double (value_type (val
), VALUE_CONTENTS (val
), &inv
);
586 error ("Invalid floating value found in program.");
589 /* Extract a value as a C pointer. Does not deallocate the value.
590 Note that val's type may not actually be a pointer; value_as_long
591 handles all the cases. */
593 value_as_address (struct value
*val
)
595 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
596 whether we want this to be true eventually. */
598 /* ADDR_BITS_REMOVE is wrong if we are being called for a
599 non-address (e.g. argument to "signal", "info break", etc.), or
600 for pointers to char, in which the low bits *are* significant. */
601 return ADDR_BITS_REMOVE (value_as_long (val
));
604 /* There are several targets (IA-64, PowerPC, and others) which
605 don't represent pointers to functions as simply the address of
606 the function's entry point. For example, on the IA-64, a
607 function pointer points to a two-word descriptor, generated by
608 the linker, which contains the function's entry point, and the
609 value the IA-64 "global pointer" register should have --- to
610 support position-independent code. The linker generates
611 descriptors only for those functions whose addresses are taken.
613 On such targets, it's difficult for GDB to convert an arbitrary
614 function address into a function pointer; it has to either find
615 an existing descriptor for that function, or call malloc and
616 build its own. On some targets, it is impossible for GDB to
617 build a descriptor at all: the descriptor must contain a jump
618 instruction; data memory cannot be executed; and code memory
621 Upon entry to this function, if VAL is a value of type `function'
622 (that is, TYPE_CODE (VALUE_TYPE (val)) == TYPE_CODE_FUNC), then
623 VALUE_ADDRESS (val) is the address of the function. This is what
624 you'll get if you evaluate an expression like `main'. The call
625 to COERCE_ARRAY below actually does all the usual unary
626 conversions, which includes converting values of type `function'
627 to `pointer to function'. This is the challenging conversion
628 discussed above. Then, `unpack_long' will convert that pointer
629 back into an address.
631 So, suppose the user types `disassemble foo' on an architecture
632 with a strange function pointer representation, on which GDB
633 cannot build its own descriptors, and suppose further that `foo'
634 has no linker-built descriptor. The address->pointer conversion
635 will signal an error and prevent the command from running, even
636 though the next step would have been to convert the pointer
637 directly back into the same address.
639 The following shortcut avoids this whole mess. If VAL is a
640 function, just return its address directly. */
641 if (TYPE_CODE (value_type (val
)) == TYPE_CODE_FUNC
642 || TYPE_CODE (value_type (val
)) == TYPE_CODE_METHOD
)
643 return VALUE_ADDRESS (val
);
645 val
= coerce_array (val
);
647 /* Some architectures (e.g. Harvard), map instruction and data
648 addresses onto a single large unified address space. For
649 instance: An architecture may consider a large integer in the
650 range 0x10000000 .. 0x1000ffff to already represent a data
651 addresses (hence not need a pointer to address conversion) while
652 a small integer would still need to be converted integer to
653 pointer to address. Just assume such architectures handle all
654 integer conversions in a single function. */
658 I think INTEGER_TO_ADDRESS is a good idea as proposed --- but we
659 must admonish GDB hackers to make sure its behavior matches the
660 compiler's, whenever possible.
662 In general, I think GDB should evaluate expressions the same way
663 the compiler does. When the user copies an expression out of
664 their source code and hands it to a `print' command, they should
665 get the same value the compiler would have computed. Any
666 deviation from this rule can cause major confusion and annoyance,
667 and needs to be justified carefully. In other words, GDB doesn't
668 really have the freedom to do these conversions in clever and
671 AndrewC pointed out that users aren't complaining about how GDB
672 casts integers to pointers; they are complaining that they can't
673 take an address from a disassembly listing and give it to `x/i'.
674 This is certainly important.
676 Adding an architecture method like integer_to_address() certainly
677 makes it possible for GDB to "get it right" in all circumstances
678 --- the target has complete control over how things get done, so
679 people can Do The Right Thing for their target without breaking
680 anyone else. The standard doesn't specify how integers get
681 converted to pointers; usually, the ABI doesn't either, but
682 ABI-specific code is a more reasonable place to handle it. */
684 if (TYPE_CODE (value_type (val
)) != TYPE_CODE_PTR
685 && TYPE_CODE (value_type (val
)) != TYPE_CODE_REF
686 && gdbarch_integer_to_address_p (current_gdbarch
))
687 return gdbarch_integer_to_address (current_gdbarch
, value_type (val
),
688 VALUE_CONTENTS (val
));
690 return unpack_long (value_type (val
), VALUE_CONTENTS (val
));
694 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
695 as a long, or as a double, assuming the raw data is described
696 by type TYPE. Knows how to convert different sizes of values
697 and can convert between fixed and floating point. We don't assume
698 any alignment for the raw data. Return value is in host byte order.
700 If you want functions and arrays to be coerced to pointers, and
701 references to be dereferenced, call value_as_long() instead.
703 C++: It is assumed that the front-end has taken care of
704 all matters concerning pointers to members. A pointer
705 to member which reaches here is considered to be equivalent
706 to an INT (or some size). After all, it is only an offset. */
709 unpack_long (struct type
*type
, const char *valaddr
)
711 enum type_code code
= TYPE_CODE (type
);
712 int len
= TYPE_LENGTH (type
);
713 int nosign
= TYPE_UNSIGNED (type
);
715 if (current_language
->la_language
== language_scm
716 && is_scmvalue_type (type
))
717 return scm_unpack (type
, valaddr
, TYPE_CODE_INT
);
721 case TYPE_CODE_TYPEDEF
:
722 return unpack_long (check_typedef (type
), valaddr
);
727 case TYPE_CODE_RANGE
:
729 return extract_unsigned_integer (valaddr
, len
);
731 return extract_signed_integer (valaddr
, len
);
734 return extract_typed_floating (valaddr
, type
);
738 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
739 whether we want this to be true eventually. */
740 return extract_typed_address (valaddr
, type
);
742 case TYPE_CODE_MEMBER
:
743 error ("not implemented: member types in unpack_long");
746 error ("Value can't be converted to integer.");
748 return 0; /* Placate lint. */
751 /* Return a double value from the specified type and address.
752 INVP points to an int which is set to 0 for valid value,
753 1 for invalid value (bad float format). In either case,
754 the returned double is OK to use. Argument is in target
755 format, result is in host format. */
758 unpack_double (struct type
*type
, const char *valaddr
, int *invp
)
764 *invp
= 0; /* Assume valid. */
765 CHECK_TYPEDEF (type
);
766 code
= TYPE_CODE (type
);
767 len
= TYPE_LENGTH (type
);
768 nosign
= TYPE_UNSIGNED (type
);
769 if (code
== TYPE_CODE_FLT
)
771 /* NOTE: cagney/2002-02-19: There was a test here to see if the
772 floating-point value was valid (using the macro
773 INVALID_FLOAT). That test/macro have been removed.
775 It turns out that only the VAX defined this macro and then
776 only in a non-portable way. Fixing the portability problem
777 wouldn't help since the VAX floating-point code is also badly
778 bit-rotten. The target needs to add definitions for the
779 methods TARGET_FLOAT_FORMAT and TARGET_DOUBLE_FORMAT - these
780 exactly describe the target floating-point format. The
781 problem here is that the corresponding floatformat_vax_f and
782 floatformat_vax_d values these methods should be set to are
783 also not defined either. Oops!
785 Hopefully someone will add both the missing floatformat
786 definitions and the new cases for floatformat_is_valid (). */
788 if (!floatformat_is_valid (floatformat_from_type (type
), valaddr
))
794 return extract_typed_floating (valaddr
, type
);
798 /* Unsigned -- be sure we compensate for signed LONGEST. */
799 return (ULONGEST
) unpack_long (type
, valaddr
);
803 /* Signed -- we are OK with unpack_long. */
804 return unpack_long (type
, valaddr
);
808 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
809 as a CORE_ADDR, assuming the raw data is described by type TYPE.
810 We don't assume any alignment for the raw data. Return value is in
813 If you want functions and arrays to be coerced to pointers, and
814 references to be dereferenced, call value_as_address() instead.
816 C++: It is assumed that the front-end has taken care of
817 all matters concerning pointers to members. A pointer
818 to member which reaches here is considered to be equivalent
819 to an INT (or some size). After all, it is only an offset. */
822 unpack_pointer (struct type
*type
, const char *valaddr
)
824 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
825 whether we want this to be true eventually. */
826 return unpack_long (type
, valaddr
);
830 /* Get the value of the FIELDN'th field (which must be static) of
831 TYPE. Return NULL if the field doesn't exist or has been
835 value_static_field (struct type
*type
, int fieldno
)
837 struct value
*retval
;
839 if (TYPE_FIELD_STATIC_HAS_ADDR (type
, fieldno
))
841 retval
= value_at (TYPE_FIELD_TYPE (type
, fieldno
),
842 TYPE_FIELD_STATIC_PHYSADDR (type
, fieldno
));
846 char *phys_name
= TYPE_FIELD_STATIC_PHYSNAME (type
, fieldno
);
847 struct symbol
*sym
= lookup_symbol (phys_name
, 0, VAR_DOMAIN
, 0, NULL
);
850 /* With some compilers, e.g. HP aCC, static data members are reported
851 as non-debuggable symbols */
852 struct minimal_symbol
*msym
= lookup_minimal_symbol (phys_name
, NULL
, NULL
);
857 retval
= value_at (TYPE_FIELD_TYPE (type
, fieldno
),
858 SYMBOL_VALUE_ADDRESS (msym
));
863 /* SYM should never have a SYMBOL_CLASS which will require
864 read_var_value to use the FRAME parameter. */
865 if (symbol_read_needs_frame (sym
))
866 warning ("static field's value depends on the current "
867 "frame - bad debug info?");
868 retval
= read_var_value (sym
, NULL
);
870 if (retval
&& VALUE_LVAL (retval
) == lval_memory
)
871 SET_FIELD_PHYSADDR (TYPE_FIELD (type
, fieldno
),
872 VALUE_ADDRESS (retval
));
877 /* Change the enclosing type of a value object VAL to NEW_ENCL_TYPE.
878 You have to be careful here, since the size of the data area for the value
879 is set by the length of the enclosing type. So if NEW_ENCL_TYPE is bigger
880 than the old enclosing type, you have to allocate more space for the data.
881 The return value is a pointer to the new version of this value structure. */
884 value_change_enclosing_type (struct value
*val
, struct type
*new_encl_type
)
886 if (TYPE_LENGTH (new_encl_type
) <= TYPE_LENGTH (value_enclosing_type (val
)))
888 val
->enclosing_type
= new_encl_type
;
893 struct value
*new_val
;
896 new_val
= (struct value
*) xrealloc (val
, sizeof (struct value
) + TYPE_LENGTH (new_encl_type
));
898 new_val
->enclosing_type
= new_encl_type
;
900 /* We have to make sure this ends up in the same place in the value
901 chain as the original copy, so it's clean-up behavior is the same.
902 If the value has been released, this is a waste of time, but there
903 is no way to tell that in advance, so... */
905 if (val
!= all_values
)
907 for (prev
= all_values
; prev
!= NULL
; prev
= prev
->next
)
909 if (prev
->next
== val
)
911 prev
->next
= new_val
;
921 /* Given a value ARG1 (offset by OFFSET bytes)
922 of a struct or union type ARG_TYPE,
923 extract and return the value of one of its (non-static) fields.
924 FIELDNO says which field. */
927 value_primitive_field (struct value
*arg1
, int offset
,
928 int fieldno
, struct type
*arg_type
)
933 CHECK_TYPEDEF (arg_type
);
934 type
= TYPE_FIELD_TYPE (arg_type
, fieldno
);
936 /* Handle packed fields */
938 if (TYPE_FIELD_BITSIZE (arg_type
, fieldno
))
940 v
= value_from_longest (type
,
941 unpack_field_as_long (arg_type
,
942 VALUE_CONTENTS (arg1
)
945 v
->bitpos
= TYPE_FIELD_BITPOS (arg_type
, fieldno
) % 8;
946 v
->bitsize
= TYPE_FIELD_BITSIZE (arg_type
, fieldno
);
947 v
->offset
= value_offset (arg1
) + offset
948 + TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
950 else if (fieldno
< TYPE_N_BASECLASSES (arg_type
))
952 /* This field is actually a base subobject, so preserve the
953 entire object's contents for later references to virtual
955 v
= allocate_value (value_enclosing_type (arg1
));
957 if (VALUE_LAZY (arg1
))
960 memcpy (value_contents_all_raw (v
), value_contents_all_raw (arg1
),
961 TYPE_LENGTH (value_enclosing_type (arg1
)));
962 v
->offset
= value_offset (arg1
);
963 VALUE_EMBEDDED_OFFSET (v
)
965 VALUE_EMBEDDED_OFFSET (arg1
) +
966 TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
970 /* Plain old data member */
971 offset
+= TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
972 v
= allocate_value (type
);
973 if (VALUE_LAZY (arg1
))
976 memcpy (value_contents_raw (v
),
977 value_contents_raw (arg1
) + offset
,
979 v
->offset
= (value_offset (arg1
) + offset
980 + VALUE_EMBEDDED_OFFSET (arg1
));
982 VALUE_LVAL (v
) = VALUE_LVAL (arg1
);
983 if (VALUE_LVAL (arg1
) == lval_internalvar
)
984 VALUE_LVAL (v
) = lval_internalvar_component
;
985 VALUE_ADDRESS (v
) = VALUE_ADDRESS (arg1
);
986 VALUE_REGNUM (v
) = VALUE_REGNUM (arg1
);
987 VALUE_FRAME_ID (v
) = VALUE_FRAME_ID (arg1
);
988 /* VALUE_OFFSET (v) = VALUE_OFFSET (arg1) + offset
989 + TYPE_FIELD_BITPOS (arg_type, fieldno) / 8; */
993 /* Given a value ARG1 of a struct or union type,
994 extract and return the value of one of its (non-static) fields.
995 FIELDNO says which field. */
998 value_field (struct value
*arg1
, int fieldno
)
1000 return value_primitive_field (arg1
, 0, fieldno
, value_type (arg1
));
1003 /* Return a non-virtual function as a value.
1004 F is the list of member functions which contains the desired method.
1005 J is an index into F which provides the desired method.
1007 We only use the symbol for its address, so be happy with either a
1008 full symbol or a minimal symbol.
1012 value_fn_field (struct value
**arg1p
, struct fn_field
*f
, int j
, struct type
*type
,
1016 struct type
*ftype
= TYPE_FN_FIELD_TYPE (f
, j
);
1017 char *physname
= TYPE_FN_FIELD_PHYSNAME (f
, j
);
1019 struct minimal_symbol
*msym
;
1021 sym
= lookup_symbol (physname
, 0, VAR_DOMAIN
, 0, NULL
);
1028 gdb_assert (sym
== NULL
);
1029 msym
= lookup_minimal_symbol (physname
, NULL
, NULL
);
1034 v
= allocate_value (ftype
);
1037 VALUE_ADDRESS (v
) = BLOCK_START (SYMBOL_BLOCK_VALUE (sym
));
1041 VALUE_ADDRESS (v
) = SYMBOL_VALUE_ADDRESS (msym
);
1046 if (type
!= value_type (*arg1p
))
1047 *arg1p
= value_ind (value_cast (lookup_pointer_type (type
),
1048 value_addr (*arg1p
)));
1050 /* Move the `this' pointer according to the offset.
1051 VALUE_OFFSET (*arg1p) += offset;
1059 /* Unpack a field FIELDNO of the specified TYPE, from the anonymous object at
1062 Extracting bits depends on endianness of the machine. Compute the
1063 number of least significant bits to discard. For big endian machines,
1064 we compute the total number of bits in the anonymous object, subtract
1065 off the bit count from the MSB of the object to the MSB of the
1066 bitfield, then the size of the bitfield, which leaves the LSB discard
1067 count. For little endian machines, the discard count is simply the
1068 number of bits from the LSB of the anonymous object to the LSB of the
1071 If the field is signed, we also do sign extension. */
1074 unpack_field_as_long (struct type
*type
, const char *valaddr
, int fieldno
)
1078 int bitpos
= TYPE_FIELD_BITPOS (type
, fieldno
);
1079 int bitsize
= TYPE_FIELD_BITSIZE (type
, fieldno
);
1081 struct type
*field_type
;
1083 val
= extract_unsigned_integer (valaddr
+ bitpos
/ 8, sizeof (val
));
1084 field_type
= TYPE_FIELD_TYPE (type
, fieldno
);
1085 CHECK_TYPEDEF (field_type
);
1087 /* Extract bits. See comment above. */
1089 if (BITS_BIG_ENDIAN
)
1090 lsbcount
= (sizeof val
* 8 - bitpos
% 8 - bitsize
);
1092 lsbcount
= (bitpos
% 8);
1095 /* If the field does not entirely fill a LONGEST, then zero the sign bits.
1096 If the field is signed, and is negative, then sign extend. */
1098 if ((bitsize
> 0) && (bitsize
< 8 * (int) sizeof (val
)))
1100 valmask
= (((ULONGEST
) 1) << bitsize
) - 1;
1102 if (!TYPE_UNSIGNED (field_type
))
1104 if (val
& (valmask
^ (valmask
>> 1)))
1113 /* Modify the value of a bitfield. ADDR points to a block of memory in
1114 target byte order; the bitfield starts in the byte pointed to. FIELDVAL
1115 is the desired value of the field, in host byte order. BITPOS and BITSIZE
1116 indicate which bits (in target bit order) comprise the bitfield.
1117 Requires 0 < BITSIZE <= lbits, 0 <= BITPOS+BITSIZE <= lbits, and
1118 0 <= BITPOS, where lbits is the size of a LONGEST in bits. */
1121 modify_field (char *addr
, LONGEST fieldval
, int bitpos
, int bitsize
)
1124 ULONGEST mask
= (ULONGEST
) -1 >> (8 * sizeof (ULONGEST
) - bitsize
);
1126 /* If a negative fieldval fits in the field in question, chop
1127 off the sign extension bits. */
1128 if ((~fieldval
& ~(mask
>> 1)) == 0)
1131 /* Warn if value is too big to fit in the field in question. */
1132 if (0 != (fieldval
& ~mask
))
1134 /* FIXME: would like to include fieldval in the message, but
1135 we don't have a sprintf_longest. */
1136 warning ("Value does not fit in %d bits.", bitsize
);
1138 /* Truncate it, otherwise adjoining fields may be corrupted. */
1142 oword
= extract_unsigned_integer (addr
, sizeof oword
);
1144 /* Shifting for bit field depends on endianness of the target machine. */
1145 if (BITS_BIG_ENDIAN
)
1146 bitpos
= sizeof (oword
) * 8 - bitpos
- bitsize
;
1148 oword
&= ~(mask
<< bitpos
);
1149 oword
|= fieldval
<< bitpos
;
1151 store_unsigned_integer (addr
, sizeof oword
, oword
);
1154 /* Convert C numbers into newly allocated values */
1157 value_from_longest (struct type
*type
, LONGEST num
)
1159 struct value
*val
= allocate_value (type
);
1160 enum type_code code
;
1163 code
= TYPE_CODE (type
);
1164 len
= TYPE_LENGTH (type
);
1168 case TYPE_CODE_TYPEDEF
:
1169 type
= check_typedef (type
);
1172 case TYPE_CODE_CHAR
:
1173 case TYPE_CODE_ENUM
:
1174 case TYPE_CODE_BOOL
:
1175 case TYPE_CODE_RANGE
:
1176 store_signed_integer (value_contents_raw (val
), len
, num
);
1181 store_typed_address (value_contents_raw (val
), type
, (CORE_ADDR
) num
);
1185 error ("Unexpected type (%d) encountered for integer constant.", code
);
1191 /* Create a value representing a pointer of type TYPE to the address
1194 value_from_pointer (struct type
*type
, CORE_ADDR addr
)
1196 struct value
*val
= allocate_value (type
);
1197 store_typed_address (value_contents_raw (val
), type
, addr
);
1202 /* Create a value for a string constant to be stored locally
1203 (not in the inferior's memory space, but in GDB memory).
1204 This is analogous to value_from_longest, which also does not
1205 use inferior memory. String shall NOT contain embedded nulls. */
1208 value_from_string (char *ptr
)
1211 int len
= strlen (ptr
);
1212 int lowbound
= current_language
->string_lower_bound
;
1213 struct type
*string_char_type
;
1214 struct type
*rangetype
;
1215 struct type
*stringtype
;
1217 rangetype
= create_range_type ((struct type
*) NULL
,
1219 lowbound
, len
+ lowbound
- 1);
1220 string_char_type
= language_string_char_type (current_language
,
1222 stringtype
= create_array_type ((struct type
*) NULL
,
1225 val
= allocate_value (stringtype
);
1226 memcpy (value_contents_raw (val
), ptr
, len
);
1231 value_from_double (struct type
*type
, DOUBLEST num
)
1233 struct value
*val
= allocate_value (type
);
1234 struct type
*base_type
= check_typedef (type
);
1235 enum type_code code
= TYPE_CODE (base_type
);
1236 int len
= TYPE_LENGTH (base_type
);
1238 if (code
== TYPE_CODE_FLT
)
1240 store_typed_floating (value_contents_raw (val
), base_type
, num
);
1243 error ("Unexpected type encountered for floating constant.");
1249 coerce_ref (struct value
*arg
)
1251 struct type
*value_type_arg_tmp
= check_typedef (value_type (arg
));
1252 if (TYPE_CODE (value_type_arg_tmp
) == TYPE_CODE_REF
)
1253 arg
= value_at_lazy (TYPE_TARGET_TYPE (value_type_arg_tmp
),
1254 unpack_pointer (value_type (arg
),
1255 VALUE_CONTENTS (arg
)));
1260 coerce_array (struct value
*arg
)
1262 arg
= coerce_ref (arg
);
1263 if (current_language
->c_style_arrays
1264 && TYPE_CODE (value_type (arg
)) == TYPE_CODE_ARRAY
)
1265 arg
= value_coerce_array (arg
);
1266 if (TYPE_CODE (value_type (arg
)) == TYPE_CODE_FUNC
)
1267 arg
= value_coerce_function (arg
);
1272 coerce_number (struct value
*arg
)
1274 arg
= coerce_array (arg
);
1275 arg
= coerce_enum (arg
);
1280 coerce_enum (struct value
*arg
)
1282 if (TYPE_CODE (check_typedef (value_type (arg
))) == TYPE_CODE_ENUM
)
1283 arg
= value_cast (builtin_type_unsigned_int
, arg
);
1288 /* Should we use DEPRECATED_EXTRACT_STRUCT_VALUE_ADDRESS instead of
1289 EXTRACT_RETURN_VALUE? GCC_P is true if compiled with gcc and TYPE
1290 is the type (which is known to be struct, union or array).
1292 On most machines, the struct convention is used unless we are
1293 using gcc and the type is of a special size. */
1294 /* As of about 31 Mar 93, GCC was changed to be compatible with the
1295 native compiler. GCC 2.3.3 was the last release that did it the
1296 old way. Since gcc2_compiled was not changed, we have no
1297 way to correctly win in all cases, so we just do the right thing
1298 for gcc1 and for gcc2 after this change. Thus it loses for gcc
1299 2.0-2.3.3. This is somewhat unfortunate, but changing gcc2_compiled
1300 would cause more chaos than dealing with some struct returns being
1302 /* NOTE: cagney/2004-06-13: Deleted check for "gcc_p". GCC 1.x is
1306 generic_use_struct_convention (int gcc_p
, struct type
*value_type
)
1308 return !(TYPE_LENGTH (value_type
) == 1
1309 || TYPE_LENGTH (value_type
) == 2
1310 || TYPE_LENGTH (value_type
) == 4
1311 || TYPE_LENGTH (value_type
) == 8);
1314 /* Return true if the function returning the specified type is using
1315 the convention of returning structures in memory (passing in the
1316 address as a hidden first parameter). GCC_P is nonzero if compiled
1320 using_struct_return (struct type
*value_type
, int gcc_p
)
1322 enum type_code code
= TYPE_CODE (value_type
);
1324 if (code
== TYPE_CODE_ERROR
)
1325 error ("Function return type unknown.");
1327 if (code
== TYPE_CODE_VOID
)
1328 /* A void return value is never in memory. See also corresponding
1329 code in "print_return_value". */
1332 /* Probe the architecture for the return-value convention. */
1333 return (gdbarch_return_value (current_gdbarch
, value_type
,
1335 != RETURN_VALUE_REGISTER_CONVENTION
);
1339 _initialize_values (void)
1341 add_cmd ("convenience", no_class
, show_convenience
,
1342 "Debugger convenience (\"$foo\") variables.\n\
1343 These variables are created when you assign them values;\n\
1344 thus, \"print $foo=1\" gives \"$foo\" the value 1. Values may be any type.\n\n\
1345 A few convenience variables are given values automatically:\n\
1346 \"$_\"holds the last address examined with \"x\" or \"info lines\",\n\
1347 \"$__\" holds the contents of the last address examined with \"x\".",
1350 add_cmd ("values", no_class
, show_values
,
1351 "Elements of value history around item number IDX (or last ten).",