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);
47 /* Type of value; either not an lval, or one of the various
48 different possible kinds of lval. */
51 /* Is it modifiable? Only relevant if lval != not_lval. */
54 /* Location of value (if lval). */
57 /* If lval == lval_memory, this is the address in the inferior.
58 If lval == lval_register, this is the byte offset into the
59 registers structure. */
62 /* Pointer to internal variable. */
63 struct internalvar
*internalvar
;
66 /* Describes offset of a value within lval of a structure in bytes.
67 If lval == lval_memory, this is an offset to the address. If
68 lval == lval_register, this is a further offset from
69 location.address within the registers structure. Note also the
70 member embedded_offset below. */
73 /* Only used for bitfields; number of bits contained in them. */
76 /* Only used for bitfields; position of start of field. For
77 BITS_BIG_ENDIAN=0 targets, it is the position of the LSB. For
78 BITS_BIG_ENDIAN=1 targets, it is the position of the MSB. */
81 /* Frame register value is relative to. This will be described in
82 the lval enum above as "lval_register". */
83 struct frame_id frame_id
;
85 /* Type of the value. */
88 /* If a value represents a C++ object, then the `type' field gives
89 the object's compile-time type. If the object actually belongs
90 to some class derived from `type', perhaps with other base
91 classes and additional members, then `type' is just a subobject
92 of the real thing, and the full object is probably larger than
95 If `type' is a dynamic class (i.e. one with a vtable), then GDB
96 can actually determine the object's run-time type by looking at
97 the run-time type information in the vtable. When this
98 information is available, we may elect to read in the entire
99 object, for several reasons:
101 - When printing the value, the user would probably rather see the
102 full object, not just the limited portion apparent from the
105 - If `type' has virtual base classes, then even printing `type'
106 alone may require reaching outside the `type' portion of the
107 object to wherever the virtual base class has been stored.
109 When we store the entire object, `enclosing_type' is the run-time
110 type -- the complete object -- and `embedded_offset' is the
111 offset of `type' within that larger type, in bytes. The
112 value_contents() macro takes `embedded_offset' into account, so
113 most GDB code continues to see the `type' portion of the value,
114 just as the inferior would.
116 If `type' is a pointer to an object, then `enclosing_type' is a
117 pointer to the object's run-time type, and `pointed_to_offset' is
118 the offset in bytes from the full object to the pointed-to object
119 -- that is, the value `embedded_offset' would have if we followed
120 the pointer and fetched the complete object. (I don't really see
121 the point. Why not just determine the run-time type when you
122 indirect, and avoid the special case? The contents don't matter
123 until you indirect anyway.)
125 If we're not doing anything fancy, `enclosing_type' is equal to
126 `type', and `embedded_offset' is zero, so everything works
128 struct type
*enclosing_type
;
130 int pointed_to_offset
;
132 /* Values are stored in a chain, so that they can be deleted easily
133 over calls to the inferior. Values assigned to internal
134 variables or put into the value history are taken off this
138 /* Register number if the value is from a register. */
141 /* If zero, contents of this value are in the contents field. If
142 nonzero, contents are in inferior memory at address in the
143 location.address field plus the offset field (and the lval field
144 should be lval_memory).
146 WARNING: This field is used by the code which handles watchpoints
147 (see breakpoint.c) to decide whether a particular value can be
148 watched by hardware watchpoints. If the lazy flag is set for
149 some member of a value chain, it is assumed that this member of
150 the chain doesn't need to be watched as part of watching the
151 value itself. This is how GDB avoids watching the entire struct
152 or array when the user wants to watch a single struct member or
153 array element. If you ever change the way lazy flag is set and
154 reset, be sure to consider this use as well! */
157 /* If nonzero, this is the value of a variable which does not
158 actually exist in the program. */
161 /* Actual contents of the value. For use of this value; setting it
162 uses the stuff above. Not valid if lazy is nonzero. Target
163 byte-order. We force it to be aligned properly for any possible
164 value. Note that a value therefore extends beyond what is
168 bfd_byte contents
[1];
169 DOUBLEST force_doublest_align
;
170 LONGEST force_longest_align
;
171 CORE_ADDR force_core_addr_align
;
172 void *force_pointer_align
;
174 /* Do not add any new members here -- contents above will trash
178 /* Prototypes for local functions. */
180 static void show_values (char *, int);
182 static void show_convenience (char *, int);
185 /* The value-history records all the values printed
186 by print commands during this session. Each chunk
187 records 60 consecutive values. The first chunk on
188 the chain records the most recent values.
189 The total number of values is in value_history_count. */
191 #define VALUE_HISTORY_CHUNK 60
193 struct value_history_chunk
195 struct value_history_chunk
*next
;
196 struct value
*values
[VALUE_HISTORY_CHUNK
];
199 /* Chain of chunks now in use. */
201 static struct value_history_chunk
*value_history_chain
;
203 static int value_history_count
; /* Abs number of last entry stored */
205 /* List of all value objects currently allocated
206 (except for those released by calls to release_value)
207 This is so they can be freed after each command. */
209 static struct value
*all_values
;
211 /* Allocate a value that has the correct length for type TYPE. */
214 allocate_value (struct type
*type
)
217 struct type
*atype
= check_typedef (type
);
219 val
= (struct value
*) xzalloc (sizeof (struct value
) + TYPE_LENGTH (atype
));
220 val
->next
= all_values
;
223 val
->enclosing_type
= type
;
224 VALUE_LVAL (val
) = not_lval
;
225 VALUE_ADDRESS (val
) = 0;
226 VALUE_FRAME_ID (val
) = null_frame_id
;
230 VALUE_REGNUM (val
) = -1;
232 val
->optimized_out
= 0;
233 val
->embedded_offset
= 0;
234 val
->pointed_to_offset
= 0;
239 /* Allocate a value that has the correct length
240 for COUNT repetitions type TYPE. */
243 allocate_repeat_value (struct type
*type
, int count
)
245 int low_bound
= current_language
->string_lower_bound
; /* ??? */
246 /* FIXME-type-allocation: need a way to free this type when we are
248 struct type
*range_type
249 = create_range_type ((struct type
*) NULL
, builtin_type_int
,
250 low_bound
, count
+ low_bound
- 1);
251 /* FIXME-type-allocation: need a way to free this type when we are
253 return allocate_value (create_array_type ((struct type
*) NULL
,
257 /* Accessor methods. */
260 value_next (struct value
*value
)
266 value_type (struct value
*value
)
271 deprecated_set_value_type (struct value
*value
, struct type
*type
)
277 value_offset (struct value
*value
)
279 return value
->offset
;
282 set_value_offset (struct value
*value
, int offset
)
284 value
->offset
= offset
;
288 value_bitpos (struct value
*value
)
290 return value
->bitpos
;
293 set_value_bitpos (struct value
*value
, int bit
)
299 value_bitsize (struct value
*value
)
301 return value
->bitsize
;
304 set_value_bitsize (struct value
*value
, int bit
)
306 value
->bitsize
= bit
;
310 value_contents_raw (struct value
*value
)
312 return value
->aligner
.contents
+ value
->embedded_offset
;
316 value_contents_all_raw (struct value
*value
)
318 return value
->aligner
.contents
;
322 value_enclosing_type (struct value
*value
)
324 return value
->enclosing_type
;
328 value_contents_all (struct value
*value
)
331 value_fetch_lazy (value
);
332 return value
->aligner
.contents
;
336 value_lazy (struct value
*value
)
342 set_value_lazy (struct value
*value
, int val
)
348 value_contents (struct value
*value
)
350 return value_contents_writeable (value
);
354 value_contents_writeable (struct value
*value
)
357 value_fetch_lazy (value
);
358 return value
->aligner
.contents
;
362 value_optimized_out (struct value
*value
)
364 return value
->optimized_out
;
368 set_value_optimized_out (struct value
*value
, int val
)
370 value
->optimized_out
= val
;
374 value_embedded_offset (struct value
*value
)
376 return value
->embedded_offset
;
380 set_value_embedded_offset (struct value
*value
, int val
)
382 value
->embedded_offset
= val
;
386 value_pointed_to_offset (struct value
*value
)
388 return value
->pointed_to_offset
;
392 set_value_pointed_to_offset (struct value
*value
, int val
)
394 value
->pointed_to_offset
= val
;
398 deprecated_value_lval_hack (struct value
*value
)
404 deprecated_value_address_hack (struct value
*value
)
406 return &value
->location
.address
;
409 struct internalvar
**
410 deprecated_value_internalvar_hack (struct value
*value
)
412 return &value
->location
.internalvar
;
416 deprecated_value_frame_id_hack (struct value
*value
)
418 return &value
->frame_id
;
422 deprecated_value_regnum_hack (struct value
*value
)
424 return &value
->regnum
;
428 deprecated_value_modifiable (struct value
*value
)
430 return value
->modifiable
;
433 deprecated_set_value_modifiable (struct value
*value
, int modifiable
)
435 value
->modifiable
= modifiable
;
438 /* Return a mark in the value chain. All values allocated after the
439 mark is obtained (except for those released) are subject to being freed
440 if a subsequent value_free_to_mark is passed the mark. */
447 /* Free all values allocated since MARK was obtained by value_mark
448 (except for those released). */
450 value_free_to_mark (struct value
*mark
)
455 for (val
= all_values
; val
&& val
!= mark
; val
= next
)
463 /* Free all the values that have been allocated (except for those released).
464 Called after each command, successful or not. */
467 free_all_values (void)
472 for (val
= all_values
; val
; val
= next
)
481 /* Remove VAL from the chain all_values
482 so it will not be freed automatically. */
485 release_value (struct value
*val
)
489 if (all_values
== val
)
491 all_values
= val
->next
;
495 for (v
= all_values
; v
; v
= v
->next
)
505 /* Release all values up to mark */
507 value_release_to_mark (struct value
*mark
)
512 for (val
= next
= all_values
; next
; next
= next
->next
)
513 if (next
->next
== mark
)
515 all_values
= next
->next
;
523 /* Return a copy of the value ARG.
524 It contains the same contents, for same memory address,
525 but it's a different block of storage. */
528 value_copy (struct value
*arg
)
530 struct type
*encl_type
= value_enclosing_type (arg
);
531 struct value
*val
= allocate_value (encl_type
);
532 val
->type
= arg
->type
;
533 VALUE_LVAL (val
) = VALUE_LVAL (arg
);
534 VALUE_ADDRESS (val
) = VALUE_ADDRESS (arg
);
535 val
->offset
= arg
->offset
;
536 val
->bitpos
= arg
->bitpos
;
537 val
->bitsize
= arg
->bitsize
;
538 VALUE_FRAME_ID (val
) = VALUE_FRAME_ID (arg
);
539 VALUE_REGNUM (val
) = VALUE_REGNUM (arg
);
540 val
->lazy
= arg
->lazy
;
541 val
->optimized_out
= arg
->optimized_out
;
542 val
->embedded_offset
= value_embedded_offset (arg
);
543 val
->pointed_to_offset
= arg
->pointed_to_offset
;
544 val
->modifiable
= arg
->modifiable
;
545 if (!value_lazy (val
))
547 memcpy (value_contents_all_raw (val
), value_contents_all_raw (arg
),
548 TYPE_LENGTH (value_enclosing_type (arg
)));
554 /* Access to the value history. */
556 /* Record a new value in the value history.
557 Returns the absolute history index of the entry.
558 Result of -1 indicates the value was not saved; otherwise it is the
559 value history index of this new item. */
562 record_latest_value (struct value
*val
)
566 /* We don't want this value to have anything to do with the inferior anymore.
567 In particular, "set $1 = 50" should not affect the variable from which
568 the value was taken, and fast watchpoints should be able to assume that
569 a value on the value history never changes. */
570 if (value_lazy (val
))
571 value_fetch_lazy (val
);
572 /* We preserve VALUE_LVAL so that the user can find out where it was fetched
573 from. This is a bit dubious, because then *&$1 does not just return $1
574 but the current contents of that location. c'est la vie... */
578 /* Here we treat value_history_count as origin-zero
579 and applying to the value being stored now. */
581 i
= value_history_count
% VALUE_HISTORY_CHUNK
;
584 struct value_history_chunk
*new
585 = (struct value_history_chunk
*)
586 xmalloc (sizeof (struct value_history_chunk
));
587 memset (new->values
, 0, sizeof new->values
);
588 new->next
= value_history_chain
;
589 value_history_chain
= new;
592 value_history_chain
->values
[i
] = val
;
594 /* Now we regard value_history_count as origin-one
595 and applying to the value just stored. */
597 return ++value_history_count
;
600 /* Return a copy of the value in the history with sequence number NUM. */
603 access_value_history (int num
)
605 struct value_history_chunk
*chunk
;
610 absnum
+= value_history_count
;
615 error ("The history is empty.");
617 error ("There is only one value in the history.");
619 error ("History does not go back to $$%d.", -num
);
621 if (absnum
> value_history_count
)
622 error ("History has not yet reached $%d.", absnum
);
626 /* Now absnum is always absolute and origin zero. */
628 chunk
= value_history_chain
;
629 for (i
= (value_history_count
- 1) / VALUE_HISTORY_CHUNK
- absnum
/ VALUE_HISTORY_CHUNK
;
633 return value_copy (chunk
->values
[absnum
% VALUE_HISTORY_CHUNK
]);
636 /* Clear the value history entirely.
637 Must be done when new symbol tables are loaded,
638 because the type pointers become invalid. */
641 clear_value_history (void)
643 struct value_history_chunk
*next
;
647 while (value_history_chain
)
649 for (i
= 0; i
< VALUE_HISTORY_CHUNK
; i
++)
650 if ((val
= value_history_chain
->values
[i
]) != NULL
)
652 next
= value_history_chain
->next
;
653 xfree (value_history_chain
);
654 value_history_chain
= next
;
656 value_history_count
= 0;
660 show_values (char *num_exp
, int from_tty
)
668 /* "info history +" should print from the stored position.
669 "info history <exp>" should print around value number <exp>. */
670 if (num_exp
[0] != '+' || num_exp
[1] != '\0')
671 num
= parse_and_eval_long (num_exp
) - 5;
675 /* "info history" means print the last 10 values. */
676 num
= value_history_count
- 9;
682 for (i
= num
; i
< num
+ 10 && i
<= value_history_count
; i
++)
684 val
= access_value_history (i
);
685 printf_filtered ("$%d = ", i
);
686 value_print (val
, gdb_stdout
, 0, Val_pretty_default
);
687 printf_filtered ("\n");
690 /* The next "info history +" should start after what we just printed. */
693 /* Hitting just return after this command should do the same thing as
694 "info history +". If num_exp is null, this is unnecessary, since
695 "info history +" is not useful after "info history". */
696 if (from_tty
&& num_exp
)
703 /* Internal variables. These are variables within the debugger
704 that hold values assigned by debugger commands.
705 The user refers to them with a '$' prefix
706 that does not appear in the variable names stored internally. */
708 static struct internalvar
*internalvars
;
710 /* Look up an internal variable with name NAME. NAME should not
711 normally include a dollar sign.
713 If the specified internal variable does not exist,
714 one is created, with a void value. */
717 lookup_internalvar (char *name
)
719 struct internalvar
*var
;
721 for (var
= internalvars
; var
; var
= var
->next
)
722 if (strcmp (var
->name
, name
) == 0)
725 var
= (struct internalvar
*) xmalloc (sizeof (struct internalvar
));
726 var
->name
= concat (name
, NULL
);
727 var
->value
= allocate_value (builtin_type_void
);
728 release_value (var
->value
);
729 var
->next
= internalvars
;
735 value_of_internalvar (struct internalvar
*var
)
739 val
= value_copy (var
->value
);
740 if (value_lazy (val
))
741 value_fetch_lazy (val
);
742 VALUE_LVAL (val
) = lval_internalvar
;
743 VALUE_INTERNALVAR (val
) = var
;
748 set_internalvar_component (struct internalvar
*var
, int offset
, int bitpos
,
749 int bitsize
, struct value
*newval
)
751 bfd_byte
*addr
= value_contents_writeable (var
->value
) + offset
;
754 modify_field (addr
, value_as_long (newval
),
757 memcpy (addr
, value_contents (newval
), TYPE_LENGTH (value_type (newval
)));
761 set_internalvar (struct internalvar
*var
, struct value
*val
)
763 struct value
*newval
;
765 newval
= value_copy (val
);
766 newval
->modifiable
= 1;
768 /* Force the value to be fetched from the target now, to avoid problems
769 later when this internalvar is referenced and the target is gone or
771 if (value_lazy (newval
))
772 value_fetch_lazy (newval
);
774 /* Begin code which must not call error(). If var->value points to
775 something free'd, an error() obviously leaves a dangling pointer.
776 But we also get a danling pointer if var->value points to
777 something in the value chain (i.e., before release_value is
778 called), because after the error free_all_values will get called before
782 release_value (newval
);
783 /* End code which must not call error(). */
787 internalvar_name (struct internalvar
*var
)
792 /* Free all internalvars. Done when new symtabs are loaded,
793 because that makes the values invalid. */
796 clear_internalvars (void)
798 struct internalvar
*var
;
803 internalvars
= var
->next
;
811 show_convenience (char *ignore
, int from_tty
)
813 struct internalvar
*var
;
816 for (var
= internalvars
; var
; var
= var
->next
)
822 printf_filtered ("$%s = ", var
->name
);
823 value_print (var
->value
, gdb_stdout
, 0, Val_pretty_default
);
824 printf_filtered ("\n");
827 printf_unfiltered ("No debugger convenience variables now defined.\n\
828 Convenience variables have names starting with \"$\";\n\
829 use \"set\" as in \"set $foo = 5\" to define them.\n");
832 /* Extract a value as a C number (either long or double).
833 Knows how to convert fixed values to double, or
834 floating values to long.
835 Does not deallocate the value. */
838 value_as_long (struct value
*val
)
840 /* This coerces arrays and functions, which is necessary (e.g.
841 in disassemble_command). It also dereferences references, which
842 I suspect is the most logical thing to do. */
843 val
= coerce_array (val
);
844 return unpack_long (value_type (val
), value_contents (val
));
848 value_as_double (struct value
*val
)
853 foo
= unpack_double (value_type (val
), value_contents (val
), &inv
);
855 error ("Invalid floating value found in program.");
858 /* Extract a value as a C pointer. Does not deallocate the value.
859 Note that val's type may not actually be a pointer; value_as_long
860 handles all the cases. */
862 value_as_address (struct value
*val
)
864 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
865 whether we want this to be true eventually. */
867 /* ADDR_BITS_REMOVE is wrong if we are being called for a
868 non-address (e.g. argument to "signal", "info break", etc.), or
869 for pointers to char, in which the low bits *are* significant. */
870 return ADDR_BITS_REMOVE (value_as_long (val
));
873 /* There are several targets (IA-64, PowerPC, and others) which
874 don't represent pointers to functions as simply the address of
875 the function's entry point. For example, on the IA-64, a
876 function pointer points to a two-word descriptor, generated by
877 the linker, which contains the function's entry point, and the
878 value the IA-64 "global pointer" register should have --- to
879 support position-independent code. The linker generates
880 descriptors only for those functions whose addresses are taken.
882 On such targets, it's difficult for GDB to convert an arbitrary
883 function address into a function pointer; it has to either find
884 an existing descriptor for that function, or call malloc and
885 build its own. On some targets, it is impossible for GDB to
886 build a descriptor at all: the descriptor must contain a jump
887 instruction; data memory cannot be executed; and code memory
890 Upon entry to this function, if VAL is a value of type `function'
891 (that is, TYPE_CODE (VALUE_TYPE (val)) == TYPE_CODE_FUNC), then
892 VALUE_ADDRESS (val) is the address of the function. This is what
893 you'll get if you evaluate an expression like `main'. The call
894 to COERCE_ARRAY below actually does all the usual unary
895 conversions, which includes converting values of type `function'
896 to `pointer to function'. This is the challenging conversion
897 discussed above. Then, `unpack_long' will convert that pointer
898 back into an address.
900 So, suppose the user types `disassemble foo' on an architecture
901 with a strange function pointer representation, on which GDB
902 cannot build its own descriptors, and suppose further that `foo'
903 has no linker-built descriptor. The address->pointer conversion
904 will signal an error and prevent the command from running, even
905 though the next step would have been to convert the pointer
906 directly back into the same address.
908 The following shortcut avoids this whole mess. If VAL is a
909 function, just return its address directly. */
910 if (TYPE_CODE (value_type (val
)) == TYPE_CODE_FUNC
911 || TYPE_CODE (value_type (val
)) == TYPE_CODE_METHOD
)
912 return VALUE_ADDRESS (val
);
914 val
= coerce_array (val
);
916 /* Some architectures (e.g. Harvard), map instruction and data
917 addresses onto a single large unified address space. For
918 instance: An architecture may consider a large integer in the
919 range 0x10000000 .. 0x1000ffff to already represent a data
920 addresses (hence not need a pointer to address conversion) while
921 a small integer would still need to be converted integer to
922 pointer to address. Just assume such architectures handle all
923 integer conversions in a single function. */
927 I think INTEGER_TO_ADDRESS is a good idea as proposed --- but we
928 must admonish GDB hackers to make sure its behavior matches the
929 compiler's, whenever possible.
931 In general, I think GDB should evaluate expressions the same way
932 the compiler does. When the user copies an expression out of
933 their source code and hands it to a `print' command, they should
934 get the same value the compiler would have computed. Any
935 deviation from this rule can cause major confusion and annoyance,
936 and needs to be justified carefully. In other words, GDB doesn't
937 really have the freedom to do these conversions in clever and
940 AndrewC pointed out that users aren't complaining about how GDB
941 casts integers to pointers; they are complaining that they can't
942 take an address from a disassembly listing and give it to `x/i'.
943 This is certainly important.
945 Adding an architecture method like integer_to_address() certainly
946 makes it possible for GDB to "get it right" in all circumstances
947 --- the target has complete control over how things get done, so
948 people can Do The Right Thing for their target without breaking
949 anyone else. The standard doesn't specify how integers get
950 converted to pointers; usually, the ABI doesn't either, but
951 ABI-specific code is a more reasonable place to handle it. */
953 if (TYPE_CODE (value_type (val
)) != TYPE_CODE_PTR
954 && TYPE_CODE (value_type (val
)) != TYPE_CODE_REF
955 && gdbarch_integer_to_address_p (current_gdbarch
))
956 return gdbarch_integer_to_address (current_gdbarch
, value_type (val
),
957 value_contents (val
));
959 return unpack_long (value_type (val
), value_contents (val
));
963 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
964 as a long, or as a double, assuming the raw data is described
965 by type TYPE. Knows how to convert different sizes of values
966 and can convert between fixed and floating point. We don't assume
967 any alignment for the raw data. Return value is in host byte order.
969 If you want functions and arrays to be coerced to pointers, and
970 references to be dereferenced, call value_as_long() instead.
972 C++: It is assumed that the front-end has taken care of
973 all matters concerning pointers to members. A pointer
974 to member which reaches here is considered to be equivalent
975 to an INT (or some size). After all, it is only an offset. */
978 unpack_long (struct type
*type
, const char *valaddr
)
980 enum type_code code
= TYPE_CODE (type
);
981 int len
= TYPE_LENGTH (type
);
982 int nosign
= TYPE_UNSIGNED (type
);
984 if (current_language
->la_language
== language_scm
985 && is_scmvalue_type (type
))
986 return scm_unpack (type
, valaddr
, TYPE_CODE_INT
);
990 case TYPE_CODE_TYPEDEF
:
991 return unpack_long (check_typedef (type
), valaddr
);
996 case TYPE_CODE_RANGE
:
998 return extract_unsigned_integer (valaddr
, len
);
1000 return extract_signed_integer (valaddr
, len
);
1003 return extract_typed_floating (valaddr
, type
);
1007 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
1008 whether we want this to be true eventually. */
1009 return extract_typed_address (valaddr
, type
);
1011 case TYPE_CODE_MEMBER
:
1012 error ("not implemented: member types in unpack_long");
1015 error ("Value can't be converted to integer.");
1017 return 0; /* Placate lint. */
1020 /* Return a double value from the specified type and address.
1021 INVP points to an int which is set to 0 for valid value,
1022 1 for invalid value (bad float format). In either case,
1023 the returned double is OK to use. Argument is in target
1024 format, result is in host format. */
1027 unpack_double (struct type
*type
, const char *valaddr
, int *invp
)
1029 enum type_code code
;
1033 *invp
= 0; /* Assume valid. */
1034 CHECK_TYPEDEF (type
);
1035 code
= TYPE_CODE (type
);
1036 len
= TYPE_LENGTH (type
);
1037 nosign
= TYPE_UNSIGNED (type
);
1038 if (code
== TYPE_CODE_FLT
)
1040 /* NOTE: cagney/2002-02-19: There was a test here to see if the
1041 floating-point value was valid (using the macro
1042 INVALID_FLOAT). That test/macro have been removed.
1044 It turns out that only the VAX defined this macro and then
1045 only in a non-portable way. Fixing the portability problem
1046 wouldn't help since the VAX floating-point code is also badly
1047 bit-rotten. The target needs to add definitions for the
1048 methods TARGET_FLOAT_FORMAT and TARGET_DOUBLE_FORMAT - these
1049 exactly describe the target floating-point format. The
1050 problem here is that the corresponding floatformat_vax_f and
1051 floatformat_vax_d values these methods should be set to are
1052 also not defined either. Oops!
1054 Hopefully someone will add both the missing floatformat
1055 definitions and the new cases for floatformat_is_valid (). */
1057 if (!floatformat_is_valid (floatformat_from_type (type
), valaddr
))
1063 return extract_typed_floating (valaddr
, type
);
1067 /* Unsigned -- be sure we compensate for signed LONGEST. */
1068 return (ULONGEST
) unpack_long (type
, valaddr
);
1072 /* Signed -- we are OK with unpack_long. */
1073 return unpack_long (type
, valaddr
);
1077 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
1078 as a CORE_ADDR, assuming the raw data is described by type TYPE.
1079 We don't assume any alignment for the raw data. Return value is in
1082 If you want functions and arrays to be coerced to pointers, and
1083 references to be dereferenced, call value_as_address() instead.
1085 C++: It is assumed that the front-end has taken care of
1086 all matters concerning pointers to members. A pointer
1087 to member which reaches here is considered to be equivalent
1088 to an INT (or some size). After all, it is only an offset. */
1091 unpack_pointer (struct type
*type
, const char *valaddr
)
1093 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
1094 whether we want this to be true eventually. */
1095 return unpack_long (type
, valaddr
);
1099 /* Get the value of the FIELDN'th field (which must be static) of
1100 TYPE. Return NULL if the field doesn't exist or has been
1104 value_static_field (struct type
*type
, int fieldno
)
1106 struct value
*retval
;
1108 if (TYPE_FIELD_STATIC_HAS_ADDR (type
, fieldno
))
1110 retval
= value_at (TYPE_FIELD_TYPE (type
, fieldno
),
1111 TYPE_FIELD_STATIC_PHYSADDR (type
, fieldno
));
1115 char *phys_name
= TYPE_FIELD_STATIC_PHYSNAME (type
, fieldno
);
1116 struct symbol
*sym
= lookup_symbol (phys_name
, 0, VAR_DOMAIN
, 0, NULL
);
1119 /* With some compilers, e.g. HP aCC, static data members are reported
1120 as non-debuggable symbols */
1121 struct minimal_symbol
*msym
= lookup_minimal_symbol (phys_name
, NULL
, NULL
);
1126 retval
= value_at (TYPE_FIELD_TYPE (type
, fieldno
),
1127 SYMBOL_VALUE_ADDRESS (msym
));
1132 /* SYM should never have a SYMBOL_CLASS which will require
1133 read_var_value to use the FRAME parameter. */
1134 if (symbol_read_needs_frame (sym
))
1135 warning ("static field's value depends on the current "
1136 "frame - bad debug info?");
1137 retval
= read_var_value (sym
, NULL
);
1139 if (retval
&& VALUE_LVAL (retval
) == lval_memory
)
1140 SET_FIELD_PHYSADDR (TYPE_FIELD (type
, fieldno
),
1141 VALUE_ADDRESS (retval
));
1146 /* Change the enclosing type of a value object VAL to NEW_ENCL_TYPE.
1147 You have to be careful here, since the size of the data area for the value
1148 is set by the length of the enclosing type. So if NEW_ENCL_TYPE is bigger
1149 than the old enclosing type, you have to allocate more space for the data.
1150 The return value is a pointer to the new version of this value structure. */
1153 value_change_enclosing_type (struct value
*val
, struct type
*new_encl_type
)
1155 if (TYPE_LENGTH (new_encl_type
) <= TYPE_LENGTH (value_enclosing_type (val
)))
1157 val
->enclosing_type
= new_encl_type
;
1162 struct value
*new_val
;
1165 new_val
= (struct value
*) xrealloc (val
, sizeof (struct value
) + TYPE_LENGTH (new_encl_type
));
1167 new_val
->enclosing_type
= new_encl_type
;
1169 /* We have to make sure this ends up in the same place in the value
1170 chain as the original copy, so it's clean-up behavior is the same.
1171 If the value has been released, this is a waste of time, but there
1172 is no way to tell that in advance, so... */
1174 if (val
!= all_values
)
1176 for (prev
= all_values
; prev
!= NULL
; prev
= prev
->next
)
1178 if (prev
->next
== val
)
1180 prev
->next
= new_val
;
1190 /* Given a value ARG1 (offset by OFFSET bytes)
1191 of a struct or union type ARG_TYPE,
1192 extract and return the value of one of its (non-static) fields.
1193 FIELDNO says which field. */
1196 value_primitive_field (struct value
*arg1
, int offset
,
1197 int fieldno
, struct type
*arg_type
)
1202 CHECK_TYPEDEF (arg_type
);
1203 type
= TYPE_FIELD_TYPE (arg_type
, fieldno
);
1205 /* Handle packed fields */
1207 if (TYPE_FIELD_BITSIZE (arg_type
, fieldno
))
1209 v
= value_from_longest (type
,
1210 unpack_field_as_long (arg_type
,
1211 value_contents (arg1
)
1214 v
->bitpos
= TYPE_FIELD_BITPOS (arg_type
, fieldno
) % 8;
1215 v
->bitsize
= TYPE_FIELD_BITSIZE (arg_type
, fieldno
);
1216 v
->offset
= value_offset (arg1
) + offset
1217 + TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
1219 else if (fieldno
< TYPE_N_BASECLASSES (arg_type
))
1221 /* This field is actually a base subobject, so preserve the
1222 entire object's contents for later references to virtual
1224 v
= allocate_value (value_enclosing_type (arg1
));
1226 if (value_lazy (arg1
))
1227 set_value_lazy (v
, 1);
1229 memcpy (value_contents_all_raw (v
), value_contents_all_raw (arg1
),
1230 TYPE_LENGTH (value_enclosing_type (arg1
)));
1231 v
->offset
= value_offset (arg1
);
1232 v
->embedded_offset
= (offset
+ value_embedded_offset (arg1
)
1233 + TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8);
1237 /* Plain old data member */
1238 offset
+= TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
1239 v
= allocate_value (type
);
1240 if (value_lazy (arg1
))
1241 set_value_lazy (v
, 1);
1243 memcpy (value_contents_raw (v
),
1244 value_contents_raw (arg1
) + offset
,
1245 TYPE_LENGTH (type
));
1246 v
->offset
= (value_offset (arg1
) + offset
1247 + value_embedded_offset (arg1
));
1249 VALUE_LVAL (v
) = VALUE_LVAL (arg1
);
1250 if (VALUE_LVAL (arg1
) == lval_internalvar
)
1251 VALUE_LVAL (v
) = lval_internalvar_component
;
1252 VALUE_ADDRESS (v
) = VALUE_ADDRESS (arg1
);
1253 VALUE_REGNUM (v
) = VALUE_REGNUM (arg1
);
1254 VALUE_FRAME_ID (v
) = VALUE_FRAME_ID (arg1
);
1255 /* VALUE_OFFSET (v) = VALUE_OFFSET (arg1) + offset
1256 + TYPE_FIELD_BITPOS (arg_type, fieldno) / 8; */
1260 /* Given a value ARG1 of a struct or union type,
1261 extract and return the value of one of its (non-static) fields.
1262 FIELDNO says which field. */
1265 value_field (struct value
*arg1
, int fieldno
)
1267 return value_primitive_field (arg1
, 0, fieldno
, value_type (arg1
));
1270 /* Return a non-virtual function as a value.
1271 F is the list of member functions which contains the desired method.
1272 J is an index into F which provides the desired method.
1274 We only use the symbol for its address, so be happy with either a
1275 full symbol or a minimal symbol.
1279 value_fn_field (struct value
**arg1p
, struct fn_field
*f
, int j
, struct type
*type
,
1283 struct type
*ftype
= TYPE_FN_FIELD_TYPE (f
, j
);
1284 char *physname
= TYPE_FN_FIELD_PHYSNAME (f
, j
);
1286 struct minimal_symbol
*msym
;
1288 sym
= lookup_symbol (physname
, 0, VAR_DOMAIN
, 0, NULL
);
1295 gdb_assert (sym
== NULL
);
1296 msym
= lookup_minimal_symbol (physname
, NULL
, NULL
);
1301 v
= allocate_value (ftype
);
1304 VALUE_ADDRESS (v
) = BLOCK_START (SYMBOL_BLOCK_VALUE (sym
));
1308 VALUE_ADDRESS (v
) = SYMBOL_VALUE_ADDRESS (msym
);
1313 if (type
!= value_type (*arg1p
))
1314 *arg1p
= value_ind (value_cast (lookup_pointer_type (type
),
1315 value_addr (*arg1p
)));
1317 /* Move the `this' pointer according to the offset.
1318 VALUE_OFFSET (*arg1p) += offset;
1326 /* Unpack a field FIELDNO of the specified TYPE, from the anonymous object at
1329 Extracting bits depends on endianness of the machine. Compute the
1330 number of least significant bits to discard. For big endian machines,
1331 we compute the total number of bits in the anonymous object, subtract
1332 off the bit count from the MSB of the object to the MSB of the
1333 bitfield, then the size of the bitfield, which leaves the LSB discard
1334 count. For little endian machines, the discard count is simply the
1335 number of bits from the LSB of the anonymous object to the LSB of the
1338 If the field is signed, we also do sign extension. */
1341 unpack_field_as_long (struct type
*type
, const char *valaddr
, int fieldno
)
1345 int bitpos
= TYPE_FIELD_BITPOS (type
, fieldno
);
1346 int bitsize
= TYPE_FIELD_BITSIZE (type
, fieldno
);
1348 struct type
*field_type
;
1350 val
= extract_unsigned_integer (valaddr
+ bitpos
/ 8, sizeof (val
));
1351 field_type
= TYPE_FIELD_TYPE (type
, fieldno
);
1352 CHECK_TYPEDEF (field_type
);
1354 /* Extract bits. See comment above. */
1356 if (BITS_BIG_ENDIAN
)
1357 lsbcount
= (sizeof val
* 8 - bitpos
% 8 - bitsize
);
1359 lsbcount
= (bitpos
% 8);
1362 /* If the field does not entirely fill a LONGEST, then zero the sign bits.
1363 If the field is signed, and is negative, then sign extend. */
1365 if ((bitsize
> 0) && (bitsize
< 8 * (int) sizeof (val
)))
1367 valmask
= (((ULONGEST
) 1) << bitsize
) - 1;
1369 if (!TYPE_UNSIGNED (field_type
))
1371 if (val
& (valmask
^ (valmask
>> 1)))
1380 /* Modify the value of a bitfield. ADDR points to a block of memory in
1381 target byte order; the bitfield starts in the byte pointed to. FIELDVAL
1382 is the desired value of the field, in host byte order. BITPOS and BITSIZE
1383 indicate which bits (in target bit order) comprise the bitfield.
1384 Requires 0 < BITSIZE <= lbits, 0 <= BITPOS+BITSIZE <= lbits, and
1385 0 <= BITPOS, where lbits is the size of a LONGEST in bits. */
1388 modify_field (char *addr
, LONGEST fieldval
, int bitpos
, int bitsize
)
1391 ULONGEST mask
= (ULONGEST
) -1 >> (8 * sizeof (ULONGEST
) - bitsize
);
1393 /* If a negative fieldval fits in the field in question, chop
1394 off the sign extension bits. */
1395 if ((~fieldval
& ~(mask
>> 1)) == 0)
1398 /* Warn if value is too big to fit in the field in question. */
1399 if (0 != (fieldval
& ~mask
))
1401 /* FIXME: would like to include fieldval in the message, but
1402 we don't have a sprintf_longest. */
1403 warning ("Value does not fit in %d bits.", bitsize
);
1405 /* Truncate it, otherwise adjoining fields may be corrupted. */
1409 oword
= extract_unsigned_integer (addr
, sizeof oword
);
1411 /* Shifting for bit field depends on endianness of the target machine. */
1412 if (BITS_BIG_ENDIAN
)
1413 bitpos
= sizeof (oword
) * 8 - bitpos
- bitsize
;
1415 oword
&= ~(mask
<< bitpos
);
1416 oword
|= fieldval
<< bitpos
;
1418 store_unsigned_integer (addr
, sizeof oword
, oword
);
1421 /* Convert C numbers into newly allocated values */
1424 value_from_longest (struct type
*type
, LONGEST num
)
1426 struct value
*val
= allocate_value (type
);
1427 enum type_code code
;
1430 code
= TYPE_CODE (type
);
1431 len
= TYPE_LENGTH (type
);
1435 case TYPE_CODE_TYPEDEF
:
1436 type
= check_typedef (type
);
1439 case TYPE_CODE_CHAR
:
1440 case TYPE_CODE_ENUM
:
1441 case TYPE_CODE_BOOL
:
1442 case TYPE_CODE_RANGE
:
1443 store_signed_integer (value_contents_raw (val
), len
, num
);
1448 store_typed_address (value_contents_raw (val
), type
, (CORE_ADDR
) num
);
1452 error ("Unexpected type (%d) encountered for integer constant.", code
);
1458 /* Create a value representing a pointer of type TYPE to the address
1461 value_from_pointer (struct type
*type
, CORE_ADDR addr
)
1463 struct value
*val
= allocate_value (type
);
1464 store_typed_address (value_contents_raw (val
), type
, addr
);
1469 /* Create a value for a string constant to be stored locally
1470 (not in the inferior's memory space, but in GDB memory).
1471 This is analogous to value_from_longest, which also does not
1472 use inferior memory. String shall NOT contain embedded nulls. */
1475 value_from_string (char *ptr
)
1478 int len
= strlen (ptr
);
1479 int lowbound
= current_language
->string_lower_bound
;
1480 struct type
*string_char_type
;
1481 struct type
*rangetype
;
1482 struct type
*stringtype
;
1484 rangetype
= create_range_type ((struct type
*) NULL
,
1486 lowbound
, len
+ lowbound
- 1);
1487 string_char_type
= language_string_char_type (current_language
,
1489 stringtype
= create_array_type ((struct type
*) NULL
,
1492 val
= allocate_value (stringtype
);
1493 memcpy (value_contents_raw (val
), ptr
, len
);
1498 value_from_double (struct type
*type
, DOUBLEST num
)
1500 struct value
*val
= allocate_value (type
);
1501 struct type
*base_type
= check_typedef (type
);
1502 enum type_code code
= TYPE_CODE (base_type
);
1503 int len
= TYPE_LENGTH (base_type
);
1505 if (code
== TYPE_CODE_FLT
)
1507 store_typed_floating (value_contents_raw (val
), base_type
, num
);
1510 error ("Unexpected type encountered for floating constant.");
1516 coerce_ref (struct value
*arg
)
1518 struct type
*value_type_arg_tmp
= check_typedef (value_type (arg
));
1519 if (TYPE_CODE (value_type_arg_tmp
) == TYPE_CODE_REF
)
1520 arg
= value_at_lazy (TYPE_TARGET_TYPE (value_type_arg_tmp
),
1521 unpack_pointer (value_type (arg
),
1522 value_contents (arg
)));
1527 coerce_array (struct value
*arg
)
1529 arg
= coerce_ref (arg
);
1530 if (current_language
->c_style_arrays
1531 && TYPE_CODE (value_type (arg
)) == TYPE_CODE_ARRAY
)
1532 arg
= value_coerce_array (arg
);
1533 if (TYPE_CODE (value_type (arg
)) == TYPE_CODE_FUNC
)
1534 arg
= value_coerce_function (arg
);
1539 coerce_number (struct value
*arg
)
1541 arg
= coerce_array (arg
);
1542 arg
= coerce_enum (arg
);
1547 coerce_enum (struct value
*arg
)
1549 if (TYPE_CODE (check_typedef (value_type (arg
))) == TYPE_CODE_ENUM
)
1550 arg
= value_cast (builtin_type_unsigned_int
, arg
);
1555 /* Should we use DEPRECATED_EXTRACT_STRUCT_VALUE_ADDRESS instead of
1556 EXTRACT_RETURN_VALUE? GCC_P is true if compiled with gcc and TYPE
1557 is the type (which is known to be struct, union or array).
1559 On most machines, the struct convention is used unless we are
1560 using gcc and the type is of a special size. */
1561 /* As of about 31 Mar 93, GCC was changed to be compatible with the
1562 native compiler. GCC 2.3.3 was the last release that did it the
1563 old way. Since gcc2_compiled was not changed, we have no
1564 way to correctly win in all cases, so we just do the right thing
1565 for gcc1 and for gcc2 after this change. Thus it loses for gcc
1566 2.0-2.3.3. This is somewhat unfortunate, but changing gcc2_compiled
1567 would cause more chaos than dealing with some struct returns being
1569 /* NOTE: cagney/2004-06-13: Deleted check for "gcc_p". GCC 1.x is
1573 generic_use_struct_convention (int gcc_p
, struct type
*value_type
)
1575 return !(TYPE_LENGTH (value_type
) == 1
1576 || TYPE_LENGTH (value_type
) == 2
1577 || TYPE_LENGTH (value_type
) == 4
1578 || TYPE_LENGTH (value_type
) == 8);
1581 /* Return true if the function returning the specified type is using
1582 the convention of returning structures in memory (passing in the
1583 address as a hidden first parameter). GCC_P is nonzero if compiled
1587 using_struct_return (struct type
*value_type
, int gcc_p
)
1589 enum type_code code
= TYPE_CODE (value_type
);
1591 if (code
== TYPE_CODE_ERROR
)
1592 error ("Function return type unknown.");
1594 if (code
== TYPE_CODE_VOID
)
1595 /* A void return value is never in memory. See also corresponding
1596 code in "print_return_value". */
1599 /* Probe the architecture for the return-value convention. */
1600 return (gdbarch_return_value (current_gdbarch
, value_type
,
1602 != RETURN_VALUE_REGISTER_CONVENTION
);
1606 _initialize_values (void)
1608 add_cmd ("convenience", no_class
, show_convenience
,
1609 "Debugger convenience (\"$foo\") variables.\n\
1610 These variables are created when you assign them values;\n\
1611 thus, \"print $foo=1\" gives \"$foo\" the value 1. Values may be any type.\n\n\
1612 A few convenience variables are given values automatically:\n\
1613 \"$_\"holds the last address examined with \"x\" or \"info lines\",\n\
1614 \"$__\" holds the contents of the last address examined with \"x\".",
1617 add_cmd ("values", no_class
, show_values
,
1618 "Elements of value history around item number IDX (or last ten).",