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. */
24 /* Hack so that value.h can detect when it's being included by
29 #include "gdb_string.h"
41 #include "gdb_assert.h"
45 /* Prototypes for exported functions. */
47 void _initialize_values (void);
49 /* Prototypes for local functions. */
51 static void show_values (char *, int);
53 static void show_convenience (char *, int);
56 /* The value-history records all the values printed
57 by print commands during this session. Each chunk
58 records 60 consecutive values. The first chunk on
59 the chain records the most recent values.
60 The total number of values is in value_history_count. */
62 #define VALUE_HISTORY_CHUNK 60
64 struct value_history_chunk
66 struct value_history_chunk
*next
;
67 struct value
*values
[VALUE_HISTORY_CHUNK
];
70 /* Chain of chunks now in use. */
72 static struct value_history_chunk
*value_history_chain
;
74 static int value_history_count
; /* Abs number of last entry stored */
76 /* List of all value objects currently allocated
77 (except for those released by calls to release_value)
78 This is so they can be freed after each command. */
80 static struct value
*all_values
;
82 /* Allocate a value that has the correct length for type TYPE. */
85 allocate_value (struct type
*type
)
88 struct type
*atype
= check_typedef (type
);
90 val
= (struct value
*) xzalloc (sizeof (struct value
) + TYPE_LENGTH (atype
));
91 val
->next
= all_values
;
94 val
->enclosing_type
= type
;
95 VALUE_LVAL (val
) = not_lval
;
96 VALUE_ADDRESS (val
) = 0;
97 VALUE_FRAME_ID (val
) = null_frame_id
;
101 VALUE_REGNUM (val
) = -1;
103 val
->optimized_out
= 0;
104 val
->embedded_offset
= 0;
105 val
->pointed_to_offset
= 0;
110 /* Allocate a value that has the correct length
111 for COUNT repetitions type TYPE. */
114 allocate_repeat_value (struct type
*type
, int count
)
116 int low_bound
= current_language
->string_lower_bound
; /* ??? */
117 /* FIXME-type-allocation: need a way to free this type when we are
119 struct type
*range_type
120 = create_range_type ((struct type
*) NULL
, builtin_type_int
,
121 low_bound
, count
+ low_bound
- 1);
122 /* FIXME-type-allocation: need a way to free this type when we are
124 return allocate_value (create_array_type ((struct type
*) NULL
,
128 /* Accessor methods. */
131 value_type (struct value
*value
)
136 deprecated_set_value_type (struct value
*value
, struct type
*type
)
142 value_offset (struct value
*value
)
144 return value
->offset
;
148 value_bitpos (struct value
*value
)
150 return value
->bitpos
;
154 value_bitsize (struct value
*value
)
156 return value
->bitsize
;
160 value_contents_raw (struct value
*value
)
162 return value
->aligner
.contents
+ value
->embedded_offset
;
166 value_contents_all_raw (struct value
*value
)
168 return value
->aligner
.contents
;
172 value_enclosing_type (struct value
*value
)
174 return value
->enclosing_type
;
178 value_contents_all (struct value
*value
)
181 value_fetch_lazy (value
);
182 return value
->aligner
.contents
;
186 value_lazy (struct value
*value
)
192 set_value_lazy (struct value
*value
, int val
)
198 value_contents (struct value
*value
)
200 return value_contents_writeable (value
);
204 value_contents_writeable (struct value
*value
)
207 value_fetch_lazy (value
);
208 return value
->aligner
.contents
;
212 value_optimized_out (struct value
*value
)
214 return value
->optimized_out
;
218 set_value_optimized_out (struct value
*value
, int val
)
220 value
->optimized_out
= val
;
224 value_embedded_offset (struct value
*value
)
226 return value
->embedded_offset
;
230 set_value_embedded_offset (struct value
*value
, int val
)
232 value
->embedded_offset
= val
;
236 value_pointed_to_offset (struct value
*value
)
238 return value
->pointed_to_offset
;
242 set_value_pointed_to_offset (struct value
*value
, int val
)
244 value
->pointed_to_offset
= val
;
248 deprecated_value_lval_hack (struct value
*value
)
254 deprecated_value_address_hack (struct value
*value
)
256 return &value
->location
.address
;
259 struct internalvar
**
260 deprecated_value_internalvar_hack (struct value
*value
)
262 return &value
->location
.internalvar
;
266 deprecated_value_frame_id_hack (struct value
*value
)
268 return &value
->frame_id
;
272 deprecated_value_regnum_hack (struct value
*value
)
274 return &value
->regnum
;
277 /* Return a mark in the value chain. All values allocated after the
278 mark is obtained (except for those released) are subject to being freed
279 if a subsequent value_free_to_mark is passed the mark. */
286 /* Free all values allocated since MARK was obtained by value_mark
287 (except for those released). */
289 value_free_to_mark (struct value
*mark
)
294 for (val
= all_values
; val
&& val
!= mark
; val
= next
)
302 /* Free all the values that have been allocated (except for those released).
303 Called after each command, successful or not. */
306 free_all_values (void)
311 for (val
= all_values
; val
; val
= next
)
320 /* Remove VAL from the chain all_values
321 so it will not be freed automatically. */
324 release_value (struct value
*val
)
328 if (all_values
== val
)
330 all_values
= val
->next
;
334 for (v
= all_values
; v
; v
= v
->next
)
344 /* Release all values up to mark */
346 value_release_to_mark (struct value
*mark
)
351 for (val
= next
= all_values
; next
; next
= next
->next
)
352 if (next
->next
== mark
)
354 all_values
= next
->next
;
362 /* Return a copy of the value ARG.
363 It contains the same contents, for same memory address,
364 but it's a different block of storage. */
367 value_copy (struct value
*arg
)
369 struct type
*encl_type
= value_enclosing_type (arg
);
370 struct value
*val
= allocate_value (encl_type
);
371 val
->type
= arg
->type
;
372 VALUE_LVAL (val
) = VALUE_LVAL (arg
);
373 VALUE_ADDRESS (val
) = VALUE_ADDRESS (arg
);
374 val
->offset
= arg
->offset
;
375 val
->bitpos
= arg
->bitpos
;
376 val
->bitsize
= arg
->bitsize
;
377 VALUE_FRAME_ID (val
) = VALUE_FRAME_ID (arg
);
378 VALUE_REGNUM (val
) = VALUE_REGNUM (arg
);
379 val
->lazy
= arg
->lazy
;
380 val
->optimized_out
= arg
->optimized_out
;
381 val
->embedded_offset
= value_embedded_offset (arg
);
382 val
->pointed_to_offset
= arg
->pointed_to_offset
;
383 val
->modifiable
= arg
->modifiable
;
384 if (!value_lazy (val
))
386 memcpy (value_contents_all_raw (val
), value_contents_all_raw (arg
),
387 TYPE_LENGTH (value_enclosing_type (arg
)));
393 /* Access to the value history. */
395 /* Record a new value in the value history.
396 Returns the absolute history index of the entry.
397 Result of -1 indicates the value was not saved; otherwise it is the
398 value history index of this new item. */
401 record_latest_value (struct value
*val
)
405 /* We don't want this value to have anything to do with the inferior anymore.
406 In particular, "set $1 = 50" should not affect the variable from which
407 the value was taken, and fast watchpoints should be able to assume that
408 a value on the value history never changes. */
409 if (value_lazy (val
))
410 value_fetch_lazy (val
);
411 /* We preserve VALUE_LVAL so that the user can find out where it was fetched
412 from. This is a bit dubious, because then *&$1 does not just return $1
413 but the current contents of that location. c'est la vie... */
417 /* Here we treat value_history_count as origin-zero
418 and applying to the value being stored now. */
420 i
= value_history_count
% VALUE_HISTORY_CHUNK
;
423 struct value_history_chunk
*new
424 = (struct value_history_chunk
*)
425 xmalloc (sizeof (struct value_history_chunk
));
426 memset (new->values
, 0, sizeof new->values
);
427 new->next
= value_history_chain
;
428 value_history_chain
= new;
431 value_history_chain
->values
[i
] = val
;
433 /* Now we regard value_history_count as origin-one
434 and applying to the value just stored. */
436 return ++value_history_count
;
439 /* Return a copy of the value in the history with sequence number NUM. */
442 access_value_history (int num
)
444 struct value_history_chunk
*chunk
;
449 absnum
+= value_history_count
;
454 error ("The history is empty.");
456 error ("There is only one value in the history.");
458 error ("History does not go back to $$%d.", -num
);
460 if (absnum
> value_history_count
)
461 error ("History has not yet reached $%d.", absnum
);
465 /* Now absnum is always absolute and origin zero. */
467 chunk
= value_history_chain
;
468 for (i
= (value_history_count
- 1) / VALUE_HISTORY_CHUNK
- absnum
/ VALUE_HISTORY_CHUNK
;
472 return value_copy (chunk
->values
[absnum
% VALUE_HISTORY_CHUNK
]);
475 /* Clear the value history entirely.
476 Must be done when new symbol tables are loaded,
477 because the type pointers become invalid. */
480 clear_value_history (void)
482 struct value_history_chunk
*next
;
486 while (value_history_chain
)
488 for (i
= 0; i
< VALUE_HISTORY_CHUNK
; i
++)
489 if ((val
= value_history_chain
->values
[i
]) != NULL
)
491 next
= value_history_chain
->next
;
492 xfree (value_history_chain
);
493 value_history_chain
= next
;
495 value_history_count
= 0;
499 show_values (char *num_exp
, int from_tty
)
507 /* "info history +" should print from the stored position.
508 "info history <exp>" should print around value number <exp>. */
509 if (num_exp
[0] != '+' || num_exp
[1] != '\0')
510 num
= parse_and_eval_long (num_exp
) - 5;
514 /* "info history" means print the last 10 values. */
515 num
= value_history_count
- 9;
521 for (i
= num
; i
< num
+ 10 && i
<= value_history_count
; i
++)
523 val
= access_value_history (i
);
524 printf_filtered ("$%d = ", i
);
525 value_print (val
, gdb_stdout
, 0, Val_pretty_default
);
526 printf_filtered ("\n");
529 /* The next "info history +" should start after what we just printed. */
532 /* Hitting just return after this command should do the same thing as
533 "info history +". If num_exp is null, this is unnecessary, since
534 "info history +" is not useful after "info history". */
535 if (from_tty
&& num_exp
)
542 /* Internal variables. These are variables within the debugger
543 that hold values assigned by debugger commands.
544 The user refers to them with a '$' prefix
545 that does not appear in the variable names stored internally. */
547 static struct internalvar
*internalvars
;
549 /* Look up an internal variable with name NAME. NAME should not
550 normally include a dollar sign.
552 If the specified internal variable does not exist,
553 one is created, with a void value. */
556 lookup_internalvar (char *name
)
558 struct internalvar
*var
;
560 for (var
= internalvars
; var
; var
= var
->next
)
561 if (strcmp (var
->name
, name
) == 0)
564 var
= (struct internalvar
*) xmalloc (sizeof (struct internalvar
));
565 var
->name
= concat (name
, NULL
);
566 var
->value
= allocate_value (builtin_type_void
);
567 release_value (var
->value
);
568 var
->next
= internalvars
;
574 value_of_internalvar (struct internalvar
*var
)
578 val
= value_copy (var
->value
);
579 if (value_lazy (val
))
580 value_fetch_lazy (val
);
581 VALUE_LVAL (val
) = lval_internalvar
;
582 VALUE_INTERNALVAR (val
) = var
;
587 set_internalvar_component (struct internalvar
*var
, int offset
, int bitpos
,
588 int bitsize
, struct value
*newval
)
590 bfd_byte
*addr
= value_contents_writeable (var
->value
) + offset
;
593 modify_field (addr
, value_as_long (newval
),
596 memcpy (addr
, value_contents (newval
), TYPE_LENGTH (value_type (newval
)));
600 set_internalvar (struct internalvar
*var
, struct value
*val
)
602 struct value
*newval
;
604 newval
= value_copy (val
);
605 newval
->modifiable
= 1;
607 /* Force the value to be fetched from the target now, to avoid problems
608 later when this internalvar is referenced and the target is gone or
610 if (value_lazy (newval
))
611 value_fetch_lazy (newval
);
613 /* Begin code which must not call error(). If var->value points to
614 something free'd, an error() obviously leaves a dangling pointer.
615 But we also get a danling pointer if var->value points to
616 something in the value chain (i.e., before release_value is
617 called), because after the error free_all_values will get called before
621 release_value (newval
);
622 /* End code which must not call error(). */
626 internalvar_name (struct internalvar
*var
)
631 /* Free all internalvars. Done when new symtabs are loaded,
632 because that makes the values invalid. */
635 clear_internalvars (void)
637 struct internalvar
*var
;
642 internalvars
= var
->next
;
650 show_convenience (char *ignore
, int from_tty
)
652 struct internalvar
*var
;
655 for (var
= internalvars
; var
; var
= var
->next
)
661 printf_filtered ("$%s = ", var
->name
);
662 value_print (var
->value
, gdb_stdout
, 0, Val_pretty_default
);
663 printf_filtered ("\n");
666 printf_unfiltered ("No debugger convenience variables now defined.\n\
667 Convenience variables have names starting with \"$\";\n\
668 use \"set\" as in \"set $foo = 5\" to define them.\n");
671 /* Extract a value as a C number (either long or double).
672 Knows how to convert fixed values to double, or
673 floating values to long.
674 Does not deallocate the value. */
677 value_as_long (struct value
*val
)
679 /* This coerces arrays and functions, which is necessary (e.g.
680 in disassemble_command). It also dereferences references, which
681 I suspect is the most logical thing to do. */
682 val
= coerce_array (val
);
683 return unpack_long (value_type (val
), value_contents (val
));
687 value_as_double (struct value
*val
)
692 foo
= unpack_double (value_type (val
), value_contents (val
), &inv
);
694 error ("Invalid floating value found in program.");
697 /* Extract a value as a C pointer. Does not deallocate the value.
698 Note that val's type may not actually be a pointer; value_as_long
699 handles all the cases. */
701 value_as_address (struct value
*val
)
703 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
704 whether we want this to be true eventually. */
706 /* ADDR_BITS_REMOVE is wrong if we are being called for a
707 non-address (e.g. argument to "signal", "info break", etc.), or
708 for pointers to char, in which the low bits *are* significant. */
709 return ADDR_BITS_REMOVE (value_as_long (val
));
712 /* There are several targets (IA-64, PowerPC, and others) which
713 don't represent pointers to functions as simply the address of
714 the function's entry point. For example, on the IA-64, a
715 function pointer points to a two-word descriptor, generated by
716 the linker, which contains the function's entry point, and the
717 value the IA-64 "global pointer" register should have --- to
718 support position-independent code. The linker generates
719 descriptors only for those functions whose addresses are taken.
721 On such targets, it's difficult for GDB to convert an arbitrary
722 function address into a function pointer; it has to either find
723 an existing descriptor for that function, or call malloc and
724 build its own. On some targets, it is impossible for GDB to
725 build a descriptor at all: the descriptor must contain a jump
726 instruction; data memory cannot be executed; and code memory
729 Upon entry to this function, if VAL is a value of type `function'
730 (that is, TYPE_CODE (VALUE_TYPE (val)) == TYPE_CODE_FUNC), then
731 VALUE_ADDRESS (val) is the address of the function. This is what
732 you'll get if you evaluate an expression like `main'. The call
733 to COERCE_ARRAY below actually does all the usual unary
734 conversions, which includes converting values of type `function'
735 to `pointer to function'. This is the challenging conversion
736 discussed above. Then, `unpack_long' will convert that pointer
737 back into an address.
739 So, suppose the user types `disassemble foo' on an architecture
740 with a strange function pointer representation, on which GDB
741 cannot build its own descriptors, and suppose further that `foo'
742 has no linker-built descriptor. The address->pointer conversion
743 will signal an error and prevent the command from running, even
744 though the next step would have been to convert the pointer
745 directly back into the same address.
747 The following shortcut avoids this whole mess. If VAL is a
748 function, just return its address directly. */
749 if (TYPE_CODE (value_type (val
)) == TYPE_CODE_FUNC
750 || TYPE_CODE (value_type (val
)) == TYPE_CODE_METHOD
)
751 return VALUE_ADDRESS (val
);
753 val
= coerce_array (val
);
755 /* Some architectures (e.g. Harvard), map instruction and data
756 addresses onto a single large unified address space. For
757 instance: An architecture may consider a large integer in the
758 range 0x10000000 .. 0x1000ffff to already represent a data
759 addresses (hence not need a pointer to address conversion) while
760 a small integer would still need to be converted integer to
761 pointer to address. Just assume such architectures handle all
762 integer conversions in a single function. */
766 I think INTEGER_TO_ADDRESS is a good idea as proposed --- but we
767 must admonish GDB hackers to make sure its behavior matches the
768 compiler's, whenever possible.
770 In general, I think GDB should evaluate expressions the same way
771 the compiler does. When the user copies an expression out of
772 their source code and hands it to a `print' command, they should
773 get the same value the compiler would have computed. Any
774 deviation from this rule can cause major confusion and annoyance,
775 and needs to be justified carefully. In other words, GDB doesn't
776 really have the freedom to do these conversions in clever and
779 AndrewC pointed out that users aren't complaining about how GDB
780 casts integers to pointers; they are complaining that they can't
781 take an address from a disassembly listing and give it to `x/i'.
782 This is certainly important.
784 Adding an architecture method like integer_to_address() certainly
785 makes it possible for GDB to "get it right" in all circumstances
786 --- the target has complete control over how things get done, so
787 people can Do The Right Thing for their target without breaking
788 anyone else. The standard doesn't specify how integers get
789 converted to pointers; usually, the ABI doesn't either, but
790 ABI-specific code is a more reasonable place to handle it. */
792 if (TYPE_CODE (value_type (val
)) != TYPE_CODE_PTR
793 && TYPE_CODE (value_type (val
)) != TYPE_CODE_REF
794 && gdbarch_integer_to_address_p (current_gdbarch
))
795 return gdbarch_integer_to_address (current_gdbarch
, value_type (val
),
796 value_contents (val
));
798 return unpack_long (value_type (val
), value_contents (val
));
802 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
803 as a long, or as a double, assuming the raw data is described
804 by type TYPE. Knows how to convert different sizes of values
805 and can convert between fixed and floating point. We don't assume
806 any alignment for the raw data. Return value is in host byte order.
808 If you want functions and arrays to be coerced to pointers, and
809 references to be dereferenced, call value_as_long() instead.
811 C++: It is assumed that the front-end has taken care of
812 all matters concerning pointers to members. A pointer
813 to member which reaches here is considered to be equivalent
814 to an INT (or some size). After all, it is only an offset. */
817 unpack_long (struct type
*type
, const char *valaddr
)
819 enum type_code code
= TYPE_CODE (type
);
820 int len
= TYPE_LENGTH (type
);
821 int nosign
= TYPE_UNSIGNED (type
);
823 if (current_language
->la_language
== language_scm
824 && is_scmvalue_type (type
))
825 return scm_unpack (type
, valaddr
, TYPE_CODE_INT
);
829 case TYPE_CODE_TYPEDEF
:
830 return unpack_long (check_typedef (type
), valaddr
);
835 case TYPE_CODE_RANGE
:
837 return extract_unsigned_integer (valaddr
, len
);
839 return extract_signed_integer (valaddr
, len
);
842 return extract_typed_floating (valaddr
, type
);
846 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
847 whether we want this to be true eventually. */
848 return extract_typed_address (valaddr
, type
);
850 case TYPE_CODE_MEMBER
:
851 error ("not implemented: member types in unpack_long");
854 error ("Value can't be converted to integer.");
856 return 0; /* Placate lint. */
859 /* Return a double value from the specified type and address.
860 INVP points to an int which is set to 0 for valid value,
861 1 for invalid value (bad float format). In either case,
862 the returned double is OK to use. Argument is in target
863 format, result is in host format. */
866 unpack_double (struct type
*type
, const char *valaddr
, int *invp
)
872 *invp
= 0; /* Assume valid. */
873 CHECK_TYPEDEF (type
);
874 code
= TYPE_CODE (type
);
875 len
= TYPE_LENGTH (type
);
876 nosign
= TYPE_UNSIGNED (type
);
877 if (code
== TYPE_CODE_FLT
)
879 /* NOTE: cagney/2002-02-19: There was a test here to see if the
880 floating-point value was valid (using the macro
881 INVALID_FLOAT). That test/macro have been removed.
883 It turns out that only the VAX defined this macro and then
884 only in a non-portable way. Fixing the portability problem
885 wouldn't help since the VAX floating-point code is also badly
886 bit-rotten. The target needs to add definitions for the
887 methods TARGET_FLOAT_FORMAT and TARGET_DOUBLE_FORMAT - these
888 exactly describe the target floating-point format. The
889 problem here is that the corresponding floatformat_vax_f and
890 floatformat_vax_d values these methods should be set to are
891 also not defined either. Oops!
893 Hopefully someone will add both the missing floatformat
894 definitions and the new cases for floatformat_is_valid (). */
896 if (!floatformat_is_valid (floatformat_from_type (type
), valaddr
))
902 return extract_typed_floating (valaddr
, type
);
906 /* Unsigned -- be sure we compensate for signed LONGEST. */
907 return (ULONGEST
) unpack_long (type
, valaddr
);
911 /* Signed -- we are OK with unpack_long. */
912 return unpack_long (type
, valaddr
);
916 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
917 as a CORE_ADDR, assuming the raw data is described by type TYPE.
918 We don't assume any alignment for the raw data. Return value is in
921 If you want functions and arrays to be coerced to pointers, and
922 references to be dereferenced, call value_as_address() instead.
924 C++: It is assumed that the front-end has taken care of
925 all matters concerning pointers to members. A pointer
926 to member which reaches here is considered to be equivalent
927 to an INT (or some size). After all, it is only an offset. */
930 unpack_pointer (struct type
*type
, const char *valaddr
)
932 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
933 whether we want this to be true eventually. */
934 return unpack_long (type
, valaddr
);
938 /* Get the value of the FIELDN'th field (which must be static) of
939 TYPE. Return NULL if the field doesn't exist or has been
943 value_static_field (struct type
*type
, int fieldno
)
945 struct value
*retval
;
947 if (TYPE_FIELD_STATIC_HAS_ADDR (type
, fieldno
))
949 retval
= value_at (TYPE_FIELD_TYPE (type
, fieldno
),
950 TYPE_FIELD_STATIC_PHYSADDR (type
, fieldno
));
954 char *phys_name
= TYPE_FIELD_STATIC_PHYSNAME (type
, fieldno
);
955 struct symbol
*sym
= lookup_symbol (phys_name
, 0, VAR_DOMAIN
, 0, NULL
);
958 /* With some compilers, e.g. HP aCC, static data members are reported
959 as non-debuggable symbols */
960 struct minimal_symbol
*msym
= lookup_minimal_symbol (phys_name
, NULL
, NULL
);
965 retval
= value_at (TYPE_FIELD_TYPE (type
, fieldno
),
966 SYMBOL_VALUE_ADDRESS (msym
));
971 /* SYM should never have a SYMBOL_CLASS which will require
972 read_var_value to use the FRAME parameter. */
973 if (symbol_read_needs_frame (sym
))
974 warning ("static field's value depends on the current "
975 "frame - bad debug info?");
976 retval
= read_var_value (sym
, NULL
);
978 if (retval
&& VALUE_LVAL (retval
) == lval_memory
)
979 SET_FIELD_PHYSADDR (TYPE_FIELD (type
, fieldno
),
980 VALUE_ADDRESS (retval
));
985 /* Change the enclosing type of a value object VAL to NEW_ENCL_TYPE.
986 You have to be careful here, since the size of the data area for the value
987 is set by the length of the enclosing type. So if NEW_ENCL_TYPE is bigger
988 than the old enclosing type, you have to allocate more space for the data.
989 The return value is a pointer to the new version of this value structure. */
992 value_change_enclosing_type (struct value
*val
, struct type
*new_encl_type
)
994 if (TYPE_LENGTH (new_encl_type
) <= TYPE_LENGTH (value_enclosing_type (val
)))
996 val
->enclosing_type
= new_encl_type
;
1001 struct value
*new_val
;
1004 new_val
= (struct value
*) xrealloc (val
, sizeof (struct value
) + TYPE_LENGTH (new_encl_type
));
1006 new_val
->enclosing_type
= new_encl_type
;
1008 /* We have to make sure this ends up in the same place in the value
1009 chain as the original copy, so it's clean-up behavior is the same.
1010 If the value has been released, this is a waste of time, but there
1011 is no way to tell that in advance, so... */
1013 if (val
!= all_values
)
1015 for (prev
= all_values
; prev
!= NULL
; prev
= prev
->next
)
1017 if (prev
->next
== val
)
1019 prev
->next
= new_val
;
1029 /* Given a value ARG1 (offset by OFFSET bytes)
1030 of a struct or union type ARG_TYPE,
1031 extract and return the value of one of its (non-static) fields.
1032 FIELDNO says which field. */
1035 value_primitive_field (struct value
*arg1
, int offset
,
1036 int fieldno
, struct type
*arg_type
)
1041 CHECK_TYPEDEF (arg_type
);
1042 type
= TYPE_FIELD_TYPE (arg_type
, fieldno
);
1044 /* Handle packed fields */
1046 if (TYPE_FIELD_BITSIZE (arg_type
, fieldno
))
1048 v
= value_from_longest (type
,
1049 unpack_field_as_long (arg_type
,
1050 value_contents (arg1
)
1053 v
->bitpos
= TYPE_FIELD_BITPOS (arg_type
, fieldno
) % 8;
1054 v
->bitsize
= TYPE_FIELD_BITSIZE (arg_type
, fieldno
);
1055 v
->offset
= value_offset (arg1
) + offset
1056 + TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
1058 else if (fieldno
< TYPE_N_BASECLASSES (arg_type
))
1060 /* This field is actually a base subobject, so preserve the
1061 entire object's contents for later references to virtual
1063 v
= allocate_value (value_enclosing_type (arg1
));
1065 if (value_lazy (arg1
))
1066 set_value_lazy (v
, 1);
1068 memcpy (value_contents_all_raw (v
), value_contents_all_raw (arg1
),
1069 TYPE_LENGTH (value_enclosing_type (arg1
)));
1070 v
->offset
= value_offset (arg1
);
1071 v
->embedded_offset
= (offset
+ value_embedded_offset (arg1
)
1072 + TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8);
1076 /* Plain old data member */
1077 offset
+= TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
1078 v
= allocate_value (type
);
1079 if (value_lazy (arg1
))
1080 set_value_lazy (v
, 1);
1082 memcpy (value_contents_raw (v
),
1083 value_contents_raw (arg1
) + offset
,
1084 TYPE_LENGTH (type
));
1085 v
->offset
= (value_offset (arg1
) + offset
1086 + value_embedded_offset (arg1
));
1088 VALUE_LVAL (v
) = VALUE_LVAL (arg1
);
1089 if (VALUE_LVAL (arg1
) == lval_internalvar
)
1090 VALUE_LVAL (v
) = lval_internalvar_component
;
1091 VALUE_ADDRESS (v
) = VALUE_ADDRESS (arg1
);
1092 VALUE_REGNUM (v
) = VALUE_REGNUM (arg1
);
1093 VALUE_FRAME_ID (v
) = VALUE_FRAME_ID (arg1
);
1094 /* VALUE_OFFSET (v) = VALUE_OFFSET (arg1) + offset
1095 + TYPE_FIELD_BITPOS (arg_type, fieldno) / 8; */
1099 /* Given a value ARG1 of a struct or union type,
1100 extract and return the value of one of its (non-static) fields.
1101 FIELDNO says which field. */
1104 value_field (struct value
*arg1
, int fieldno
)
1106 return value_primitive_field (arg1
, 0, fieldno
, value_type (arg1
));
1109 /* Return a non-virtual function as a value.
1110 F is the list of member functions which contains the desired method.
1111 J is an index into F which provides the desired method.
1113 We only use the symbol for its address, so be happy with either a
1114 full symbol or a minimal symbol.
1118 value_fn_field (struct value
**arg1p
, struct fn_field
*f
, int j
, struct type
*type
,
1122 struct type
*ftype
= TYPE_FN_FIELD_TYPE (f
, j
);
1123 char *physname
= TYPE_FN_FIELD_PHYSNAME (f
, j
);
1125 struct minimal_symbol
*msym
;
1127 sym
= lookup_symbol (physname
, 0, VAR_DOMAIN
, 0, NULL
);
1134 gdb_assert (sym
== NULL
);
1135 msym
= lookup_minimal_symbol (physname
, NULL
, NULL
);
1140 v
= allocate_value (ftype
);
1143 VALUE_ADDRESS (v
) = BLOCK_START (SYMBOL_BLOCK_VALUE (sym
));
1147 VALUE_ADDRESS (v
) = SYMBOL_VALUE_ADDRESS (msym
);
1152 if (type
!= value_type (*arg1p
))
1153 *arg1p
= value_ind (value_cast (lookup_pointer_type (type
),
1154 value_addr (*arg1p
)));
1156 /* Move the `this' pointer according to the offset.
1157 VALUE_OFFSET (*arg1p) += offset;
1165 /* Unpack a field FIELDNO of the specified TYPE, from the anonymous object at
1168 Extracting bits depends on endianness of the machine. Compute the
1169 number of least significant bits to discard. For big endian machines,
1170 we compute the total number of bits in the anonymous object, subtract
1171 off the bit count from the MSB of the object to the MSB of the
1172 bitfield, then the size of the bitfield, which leaves the LSB discard
1173 count. For little endian machines, the discard count is simply the
1174 number of bits from the LSB of the anonymous object to the LSB of the
1177 If the field is signed, we also do sign extension. */
1180 unpack_field_as_long (struct type
*type
, const char *valaddr
, int fieldno
)
1184 int bitpos
= TYPE_FIELD_BITPOS (type
, fieldno
);
1185 int bitsize
= TYPE_FIELD_BITSIZE (type
, fieldno
);
1187 struct type
*field_type
;
1189 val
= extract_unsigned_integer (valaddr
+ bitpos
/ 8, sizeof (val
));
1190 field_type
= TYPE_FIELD_TYPE (type
, fieldno
);
1191 CHECK_TYPEDEF (field_type
);
1193 /* Extract bits. See comment above. */
1195 if (BITS_BIG_ENDIAN
)
1196 lsbcount
= (sizeof val
* 8 - bitpos
% 8 - bitsize
);
1198 lsbcount
= (bitpos
% 8);
1201 /* If the field does not entirely fill a LONGEST, then zero the sign bits.
1202 If the field is signed, and is negative, then sign extend. */
1204 if ((bitsize
> 0) && (bitsize
< 8 * (int) sizeof (val
)))
1206 valmask
= (((ULONGEST
) 1) << bitsize
) - 1;
1208 if (!TYPE_UNSIGNED (field_type
))
1210 if (val
& (valmask
^ (valmask
>> 1)))
1219 /* Modify the value of a bitfield. ADDR points to a block of memory in
1220 target byte order; the bitfield starts in the byte pointed to. FIELDVAL
1221 is the desired value of the field, in host byte order. BITPOS and BITSIZE
1222 indicate which bits (in target bit order) comprise the bitfield.
1223 Requires 0 < BITSIZE <= lbits, 0 <= BITPOS+BITSIZE <= lbits, and
1224 0 <= BITPOS, where lbits is the size of a LONGEST in bits. */
1227 modify_field (char *addr
, LONGEST fieldval
, int bitpos
, int bitsize
)
1230 ULONGEST mask
= (ULONGEST
) -1 >> (8 * sizeof (ULONGEST
) - bitsize
);
1232 /* If a negative fieldval fits in the field in question, chop
1233 off the sign extension bits. */
1234 if ((~fieldval
& ~(mask
>> 1)) == 0)
1237 /* Warn if value is too big to fit in the field in question. */
1238 if (0 != (fieldval
& ~mask
))
1240 /* FIXME: would like to include fieldval in the message, but
1241 we don't have a sprintf_longest. */
1242 warning ("Value does not fit in %d bits.", bitsize
);
1244 /* Truncate it, otherwise adjoining fields may be corrupted. */
1248 oword
= extract_unsigned_integer (addr
, sizeof oword
);
1250 /* Shifting for bit field depends on endianness of the target machine. */
1251 if (BITS_BIG_ENDIAN
)
1252 bitpos
= sizeof (oword
) * 8 - bitpos
- bitsize
;
1254 oword
&= ~(mask
<< bitpos
);
1255 oword
|= fieldval
<< bitpos
;
1257 store_unsigned_integer (addr
, sizeof oword
, oword
);
1260 /* Convert C numbers into newly allocated values */
1263 value_from_longest (struct type
*type
, LONGEST num
)
1265 struct value
*val
= allocate_value (type
);
1266 enum type_code code
;
1269 code
= TYPE_CODE (type
);
1270 len
= TYPE_LENGTH (type
);
1274 case TYPE_CODE_TYPEDEF
:
1275 type
= check_typedef (type
);
1278 case TYPE_CODE_CHAR
:
1279 case TYPE_CODE_ENUM
:
1280 case TYPE_CODE_BOOL
:
1281 case TYPE_CODE_RANGE
:
1282 store_signed_integer (value_contents_raw (val
), len
, num
);
1287 store_typed_address (value_contents_raw (val
), type
, (CORE_ADDR
) num
);
1291 error ("Unexpected type (%d) encountered for integer constant.", code
);
1297 /* Create a value representing a pointer of type TYPE to the address
1300 value_from_pointer (struct type
*type
, CORE_ADDR addr
)
1302 struct value
*val
= allocate_value (type
);
1303 store_typed_address (value_contents_raw (val
), type
, addr
);
1308 /* Create a value for a string constant to be stored locally
1309 (not in the inferior's memory space, but in GDB memory).
1310 This is analogous to value_from_longest, which also does not
1311 use inferior memory. String shall NOT contain embedded nulls. */
1314 value_from_string (char *ptr
)
1317 int len
= strlen (ptr
);
1318 int lowbound
= current_language
->string_lower_bound
;
1319 struct type
*string_char_type
;
1320 struct type
*rangetype
;
1321 struct type
*stringtype
;
1323 rangetype
= create_range_type ((struct type
*) NULL
,
1325 lowbound
, len
+ lowbound
- 1);
1326 string_char_type
= language_string_char_type (current_language
,
1328 stringtype
= create_array_type ((struct type
*) NULL
,
1331 val
= allocate_value (stringtype
);
1332 memcpy (value_contents_raw (val
), ptr
, len
);
1337 value_from_double (struct type
*type
, DOUBLEST num
)
1339 struct value
*val
= allocate_value (type
);
1340 struct type
*base_type
= check_typedef (type
);
1341 enum type_code code
= TYPE_CODE (base_type
);
1342 int len
= TYPE_LENGTH (base_type
);
1344 if (code
== TYPE_CODE_FLT
)
1346 store_typed_floating (value_contents_raw (val
), base_type
, num
);
1349 error ("Unexpected type encountered for floating constant.");
1355 coerce_ref (struct value
*arg
)
1357 struct type
*value_type_arg_tmp
= check_typedef (value_type (arg
));
1358 if (TYPE_CODE (value_type_arg_tmp
) == TYPE_CODE_REF
)
1359 arg
= value_at_lazy (TYPE_TARGET_TYPE (value_type_arg_tmp
),
1360 unpack_pointer (value_type (arg
),
1361 value_contents (arg
)));
1366 coerce_array (struct value
*arg
)
1368 arg
= coerce_ref (arg
);
1369 if (current_language
->c_style_arrays
1370 && TYPE_CODE (value_type (arg
)) == TYPE_CODE_ARRAY
)
1371 arg
= value_coerce_array (arg
);
1372 if (TYPE_CODE (value_type (arg
)) == TYPE_CODE_FUNC
)
1373 arg
= value_coerce_function (arg
);
1378 coerce_number (struct value
*arg
)
1380 arg
= coerce_array (arg
);
1381 arg
= coerce_enum (arg
);
1386 coerce_enum (struct value
*arg
)
1388 if (TYPE_CODE (check_typedef (value_type (arg
))) == TYPE_CODE_ENUM
)
1389 arg
= value_cast (builtin_type_unsigned_int
, arg
);
1394 /* Should we use DEPRECATED_EXTRACT_STRUCT_VALUE_ADDRESS instead of
1395 EXTRACT_RETURN_VALUE? GCC_P is true if compiled with gcc and TYPE
1396 is the type (which is known to be struct, union or array).
1398 On most machines, the struct convention is used unless we are
1399 using gcc and the type is of a special size. */
1400 /* As of about 31 Mar 93, GCC was changed to be compatible with the
1401 native compiler. GCC 2.3.3 was the last release that did it the
1402 old way. Since gcc2_compiled was not changed, we have no
1403 way to correctly win in all cases, so we just do the right thing
1404 for gcc1 and for gcc2 after this change. Thus it loses for gcc
1405 2.0-2.3.3. This is somewhat unfortunate, but changing gcc2_compiled
1406 would cause more chaos than dealing with some struct returns being
1408 /* NOTE: cagney/2004-06-13: Deleted check for "gcc_p". GCC 1.x is
1412 generic_use_struct_convention (int gcc_p
, struct type
*value_type
)
1414 return !(TYPE_LENGTH (value_type
) == 1
1415 || TYPE_LENGTH (value_type
) == 2
1416 || TYPE_LENGTH (value_type
) == 4
1417 || TYPE_LENGTH (value_type
) == 8);
1420 /* Return true if the function returning the specified type is using
1421 the convention of returning structures in memory (passing in the
1422 address as a hidden first parameter). GCC_P is nonzero if compiled
1426 using_struct_return (struct type
*value_type
, int gcc_p
)
1428 enum type_code code
= TYPE_CODE (value_type
);
1430 if (code
== TYPE_CODE_ERROR
)
1431 error ("Function return type unknown.");
1433 if (code
== TYPE_CODE_VOID
)
1434 /* A void return value is never in memory. See also corresponding
1435 code in "print_return_value". */
1438 /* Probe the architecture for the return-value convention. */
1439 return (gdbarch_return_value (current_gdbarch
, value_type
,
1441 != RETURN_VALUE_REGISTER_CONVENTION
);
1445 _initialize_values (void)
1447 add_cmd ("convenience", no_class
, show_convenience
,
1448 "Debugger convenience (\"$foo\") variables.\n\
1449 These variables are created when you assign them values;\n\
1450 thus, \"print $foo=1\" gives \"$foo\" the value 1. Values may be any type.\n\n\
1451 A few convenience variables are given values automatically:\n\
1452 \"$_\"holds the last address examined with \"x\" or \"info lines\",\n\
1453 \"$__\" holds the contents of the last address examined with \"x\".",
1456 add_cmd ("values", no_class
, show_values
,
1457 "Elements of value history around item number IDX (or last ten).",