1 /* Low level packing and unpacking of values for GDB, the GNU Debugger.
3 Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
4 1995, 1996, 1997, 1998, 1999, 2000, 2002, 2003, 2004, 2005, 2006
5 Free 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., 51 Franklin Street, Fifth Floor,
22 Boston, MA 02110-1301, 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 gdb_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_contents_raw (value
);
361 /* Return non-zero if VAL1 and VAL2 have the same contents. Note that
362 this function is different from value_equal; in C the operator ==
363 can return 0 even if the two values being compared are equal. */
366 value_contents_equal (struct value
*val1
, struct value
*val2
)
372 type1
= check_typedef (value_type (val1
));
373 type2
= check_typedef (value_type (val2
));
374 len
= TYPE_LENGTH (type1
);
375 if (len
!= TYPE_LENGTH (type2
))
378 return (memcmp (value_contents (val1
), value_contents (val2
), len
) == 0);
382 value_optimized_out (struct value
*value
)
384 return value
->optimized_out
;
388 set_value_optimized_out (struct value
*value
, int val
)
390 value
->optimized_out
= val
;
394 value_embedded_offset (struct value
*value
)
396 return value
->embedded_offset
;
400 set_value_embedded_offset (struct value
*value
, int val
)
402 value
->embedded_offset
= val
;
406 value_pointed_to_offset (struct value
*value
)
408 return value
->pointed_to_offset
;
412 set_value_pointed_to_offset (struct value
*value
, int val
)
414 value
->pointed_to_offset
= val
;
418 deprecated_value_lval_hack (struct value
*value
)
424 deprecated_value_address_hack (struct value
*value
)
426 return &value
->location
.address
;
429 struct internalvar
**
430 deprecated_value_internalvar_hack (struct value
*value
)
432 return &value
->location
.internalvar
;
436 deprecated_value_frame_id_hack (struct value
*value
)
438 return &value
->frame_id
;
442 deprecated_value_regnum_hack (struct value
*value
)
444 return &value
->regnum
;
448 deprecated_value_modifiable (struct value
*value
)
450 return value
->modifiable
;
453 deprecated_set_value_modifiable (struct value
*value
, int modifiable
)
455 value
->modifiable
= modifiable
;
458 /* Return a mark in the value chain. All values allocated after the
459 mark is obtained (except for those released) are subject to being freed
460 if a subsequent value_free_to_mark is passed the mark. */
467 /* Free all values allocated since MARK was obtained by value_mark
468 (except for those released). */
470 value_free_to_mark (struct value
*mark
)
475 for (val
= all_values
; val
&& val
!= mark
; val
= next
)
483 /* Free all the values that have been allocated (except for those released).
484 Called after each command, successful or not. */
487 free_all_values (void)
492 for (val
= all_values
; val
; val
= next
)
501 /* Remove VAL from the chain all_values
502 so it will not be freed automatically. */
505 release_value (struct value
*val
)
509 if (all_values
== val
)
511 all_values
= val
->next
;
515 for (v
= all_values
; v
; v
= v
->next
)
525 /* Release all values up to mark */
527 value_release_to_mark (struct value
*mark
)
532 for (val
= next
= all_values
; next
; next
= next
->next
)
533 if (next
->next
== mark
)
535 all_values
= next
->next
;
543 /* Return a copy of the value ARG.
544 It contains the same contents, for same memory address,
545 but it's a different block of storage. */
548 value_copy (struct value
*arg
)
550 struct type
*encl_type
= value_enclosing_type (arg
);
551 struct value
*val
= allocate_value (encl_type
);
552 val
->type
= arg
->type
;
553 VALUE_LVAL (val
) = VALUE_LVAL (arg
);
554 VALUE_ADDRESS (val
) = VALUE_ADDRESS (arg
);
555 val
->offset
= arg
->offset
;
556 val
->bitpos
= arg
->bitpos
;
557 val
->bitsize
= arg
->bitsize
;
558 VALUE_FRAME_ID (val
) = VALUE_FRAME_ID (arg
);
559 VALUE_REGNUM (val
) = VALUE_REGNUM (arg
);
560 val
->lazy
= arg
->lazy
;
561 val
->optimized_out
= arg
->optimized_out
;
562 val
->embedded_offset
= value_embedded_offset (arg
);
563 val
->pointed_to_offset
= arg
->pointed_to_offset
;
564 val
->modifiable
= arg
->modifiable
;
565 if (!value_lazy (val
))
567 memcpy (value_contents_all_raw (val
), value_contents_all_raw (arg
),
568 TYPE_LENGTH (value_enclosing_type (arg
)));
574 /* Access to the value history. */
576 /* Record a new value in the value history.
577 Returns the absolute history index of the entry.
578 Result of -1 indicates the value was not saved; otherwise it is the
579 value history index of this new item. */
582 record_latest_value (struct value
*val
)
586 /* We don't want this value to have anything to do with the inferior anymore.
587 In particular, "set $1 = 50" should not affect the variable from which
588 the value was taken, and fast watchpoints should be able to assume that
589 a value on the value history never changes. */
590 if (value_lazy (val
))
591 value_fetch_lazy (val
);
592 /* We preserve VALUE_LVAL so that the user can find out where it was fetched
593 from. This is a bit dubious, because then *&$1 does not just return $1
594 but the current contents of that location. c'est la vie... */
598 /* Here we treat value_history_count as origin-zero
599 and applying to the value being stored now. */
601 i
= value_history_count
% VALUE_HISTORY_CHUNK
;
604 struct value_history_chunk
*new
605 = (struct value_history_chunk
*)
606 xmalloc (sizeof (struct value_history_chunk
));
607 memset (new->values
, 0, sizeof new->values
);
608 new->next
= value_history_chain
;
609 value_history_chain
= new;
612 value_history_chain
->values
[i
] = val
;
614 /* Now we regard value_history_count as origin-one
615 and applying to the value just stored. */
617 return ++value_history_count
;
620 /* Return a copy of the value in the history with sequence number NUM. */
623 access_value_history (int num
)
625 struct value_history_chunk
*chunk
;
630 absnum
+= value_history_count
;
635 error (_("The history is empty."));
637 error (_("There is only one value in the history."));
639 error (_("History does not go back to $$%d."), -num
);
641 if (absnum
> value_history_count
)
642 error (_("History has not yet reached $%d."), absnum
);
646 /* Now absnum is always absolute and origin zero. */
648 chunk
= value_history_chain
;
649 for (i
= (value_history_count
- 1) / VALUE_HISTORY_CHUNK
- absnum
/ VALUE_HISTORY_CHUNK
;
653 return value_copy (chunk
->values
[absnum
% VALUE_HISTORY_CHUNK
]);
656 /* Clear the value history entirely.
657 Must be done when new symbol tables are loaded,
658 because the type pointers become invalid. */
661 clear_value_history (void)
663 struct value_history_chunk
*next
;
667 while (value_history_chain
)
669 for (i
= 0; i
< VALUE_HISTORY_CHUNK
; i
++)
670 if ((val
= value_history_chain
->values
[i
]) != NULL
)
672 next
= value_history_chain
->next
;
673 xfree (value_history_chain
);
674 value_history_chain
= next
;
676 value_history_count
= 0;
680 show_values (char *num_exp
, int from_tty
)
688 /* "info history +" should print from the stored position.
689 "info history <exp>" should print around value number <exp>. */
690 if (num_exp
[0] != '+' || num_exp
[1] != '\0')
691 num
= parse_and_eval_long (num_exp
) - 5;
695 /* "info history" means print the last 10 values. */
696 num
= value_history_count
- 9;
702 for (i
= num
; i
< num
+ 10 && i
<= value_history_count
; i
++)
704 val
= access_value_history (i
);
705 printf_filtered (("$%d = "), i
);
706 value_print (val
, gdb_stdout
, 0, Val_pretty_default
);
707 printf_filtered (("\n"));
710 /* The next "info history +" should start after what we just printed. */
713 /* Hitting just return after this command should do the same thing as
714 "info history +". If num_exp is null, this is unnecessary, since
715 "info history +" is not useful after "info history". */
716 if (from_tty
&& num_exp
)
723 /* Internal variables. These are variables within the debugger
724 that hold values assigned by debugger commands.
725 The user refers to them with a '$' prefix
726 that does not appear in the variable names stored internally. */
728 static struct internalvar
*internalvars
;
730 /* If the variable does not already exist create it and give it the value given.
731 If no value is given then the default is zero. */
733 init_if_undefined_command (char* args
, int from_tty
)
735 struct internalvar
* intvar
;
737 /* Parse the expression - this is taken from set_command(). */
738 struct expression
*expr
= parse_expression (args
);
739 register struct cleanup
*old_chain
=
740 make_cleanup (free_current_contents
, &expr
);
742 /* Validate the expression.
743 Was the expression an assignment?
744 Or even an expression at all? */
745 if (expr
->nelts
== 0 || expr
->elts
[0].opcode
!= BINOP_ASSIGN
)
746 error (_("Init-if-undefined requires an assignment expression."));
748 /* Extract the variable from the parsed expression.
749 In the case of an assign the lvalue will be in elts[1] and elts[2]. */
750 if (expr
->elts
[1].opcode
!= OP_INTERNALVAR
)
751 error (_("The first parameter to init-if-undefined should be a GDB variable."));
752 intvar
= expr
->elts
[2].internalvar
;
754 /* Only evaluate the expression if the lvalue is void.
755 This may still fail if the expresssion is invalid. */
756 if (TYPE_CODE (value_type (intvar
->value
)) == TYPE_CODE_VOID
)
757 evaluate_expression (expr
);
759 do_cleanups (old_chain
);
763 /* Look up an internal variable with name NAME. NAME should not
764 normally include a dollar sign.
766 If the specified internal variable does not exist,
767 one is created, with a void value. */
770 lookup_internalvar (char *name
)
772 struct internalvar
*var
;
774 for (var
= internalvars
; var
; var
= var
->next
)
775 if (strcmp (var
->name
, name
) == 0)
778 var
= (struct internalvar
*) xmalloc (sizeof (struct internalvar
));
779 var
->name
= concat (name
, (char *)NULL
);
780 var
->value
= allocate_value (builtin_type_void
);
781 release_value (var
->value
);
782 var
->next
= internalvars
;
788 value_of_internalvar (struct internalvar
*var
)
792 val
= value_copy (var
->value
);
793 if (value_lazy (val
))
794 value_fetch_lazy (val
);
795 VALUE_LVAL (val
) = lval_internalvar
;
796 VALUE_INTERNALVAR (val
) = var
;
801 set_internalvar_component (struct internalvar
*var
, int offset
, int bitpos
,
802 int bitsize
, struct value
*newval
)
804 gdb_byte
*addr
= value_contents_writeable (var
->value
) + offset
;
807 modify_field (addr
, value_as_long (newval
),
810 memcpy (addr
, value_contents (newval
), TYPE_LENGTH (value_type (newval
)));
814 set_internalvar (struct internalvar
*var
, struct value
*val
)
816 struct value
*newval
;
818 newval
= value_copy (val
);
819 newval
->modifiable
= 1;
821 /* Force the value to be fetched from the target now, to avoid problems
822 later when this internalvar is referenced and the target is gone or
824 if (value_lazy (newval
))
825 value_fetch_lazy (newval
);
827 /* Begin code which must not call error(). If var->value points to
828 something free'd, an error() obviously leaves a dangling pointer.
829 But we also get a danling pointer if var->value points to
830 something in the value chain (i.e., before release_value is
831 called), because after the error free_all_values will get called before
835 release_value (newval
);
836 /* End code which must not call error(). */
840 internalvar_name (struct internalvar
*var
)
845 /* Free all internalvars. Done when new symtabs are loaded,
846 because that makes the values invalid. */
849 clear_internalvars (void)
851 struct internalvar
*var
;
856 internalvars
= var
->next
;
864 show_convenience (char *ignore
, int from_tty
)
866 struct internalvar
*var
;
869 for (var
= internalvars
; var
; var
= var
->next
)
875 printf_filtered (("$%s = "), var
->name
);
876 value_print (var
->value
, gdb_stdout
, 0, Val_pretty_default
);
877 printf_filtered (("\n"));
880 printf_unfiltered (_("\
881 No debugger convenience variables now defined.\n\
882 Convenience variables have names starting with \"$\";\n\
883 use \"set\" as in \"set $foo = 5\" to define them.\n"));
886 /* Extract a value as a C number (either long or double).
887 Knows how to convert fixed values to double, or
888 floating values to long.
889 Does not deallocate the value. */
892 value_as_long (struct value
*val
)
894 /* This coerces arrays and functions, which is necessary (e.g.
895 in disassemble_command). It also dereferences references, which
896 I suspect is the most logical thing to do. */
897 val
= coerce_array (val
);
898 return unpack_long (value_type (val
), value_contents (val
));
902 value_as_double (struct value
*val
)
907 foo
= unpack_double (value_type (val
), value_contents (val
), &inv
);
909 error (_("Invalid floating value found in program."));
912 /* Extract a value as a C pointer. Does not deallocate the value.
913 Note that val's type may not actually be a pointer; value_as_long
914 handles all the cases. */
916 value_as_address (struct value
*val
)
918 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
919 whether we want this to be true eventually. */
921 /* ADDR_BITS_REMOVE is wrong if we are being called for a
922 non-address (e.g. argument to "signal", "info break", etc.), or
923 for pointers to char, in which the low bits *are* significant. */
924 return ADDR_BITS_REMOVE (value_as_long (val
));
927 /* There are several targets (IA-64, PowerPC, and others) which
928 don't represent pointers to functions as simply the address of
929 the function's entry point. For example, on the IA-64, a
930 function pointer points to a two-word descriptor, generated by
931 the linker, which contains the function's entry point, and the
932 value the IA-64 "global pointer" register should have --- to
933 support position-independent code. The linker generates
934 descriptors only for those functions whose addresses are taken.
936 On such targets, it's difficult for GDB to convert an arbitrary
937 function address into a function pointer; it has to either find
938 an existing descriptor for that function, or call malloc and
939 build its own. On some targets, it is impossible for GDB to
940 build a descriptor at all: the descriptor must contain a jump
941 instruction; data memory cannot be executed; and code memory
944 Upon entry to this function, if VAL is a value of type `function'
945 (that is, TYPE_CODE (VALUE_TYPE (val)) == TYPE_CODE_FUNC), then
946 VALUE_ADDRESS (val) is the address of the function. This is what
947 you'll get if you evaluate an expression like `main'. The call
948 to COERCE_ARRAY below actually does all the usual unary
949 conversions, which includes converting values of type `function'
950 to `pointer to function'. This is the challenging conversion
951 discussed above. Then, `unpack_long' will convert that pointer
952 back into an address.
954 So, suppose the user types `disassemble foo' on an architecture
955 with a strange function pointer representation, on which GDB
956 cannot build its own descriptors, and suppose further that `foo'
957 has no linker-built descriptor. The address->pointer conversion
958 will signal an error and prevent the command from running, even
959 though the next step would have been to convert the pointer
960 directly back into the same address.
962 The following shortcut avoids this whole mess. If VAL is a
963 function, just return its address directly. */
964 if (TYPE_CODE (value_type (val
)) == TYPE_CODE_FUNC
965 || TYPE_CODE (value_type (val
)) == TYPE_CODE_METHOD
)
966 return VALUE_ADDRESS (val
);
968 val
= coerce_array (val
);
970 /* Some architectures (e.g. Harvard), map instruction and data
971 addresses onto a single large unified address space. For
972 instance: An architecture may consider a large integer in the
973 range 0x10000000 .. 0x1000ffff to already represent a data
974 addresses (hence not need a pointer to address conversion) while
975 a small integer would still need to be converted integer to
976 pointer to address. Just assume such architectures handle all
977 integer conversions in a single function. */
981 I think INTEGER_TO_ADDRESS is a good idea as proposed --- but we
982 must admonish GDB hackers to make sure its behavior matches the
983 compiler's, whenever possible.
985 In general, I think GDB should evaluate expressions the same way
986 the compiler does. When the user copies an expression out of
987 their source code and hands it to a `print' command, they should
988 get the same value the compiler would have computed. Any
989 deviation from this rule can cause major confusion and annoyance,
990 and needs to be justified carefully. In other words, GDB doesn't
991 really have the freedom to do these conversions in clever and
994 AndrewC pointed out that users aren't complaining about how GDB
995 casts integers to pointers; they are complaining that they can't
996 take an address from a disassembly listing and give it to `x/i'.
997 This is certainly important.
999 Adding an architecture method like integer_to_address() certainly
1000 makes it possible for GDB to "get it right" in all circumstances
1001 --- the target has complete control over how things get done, so
1002 people can Do The Right Thing for their target without breaking
1003 anyone else. The standard doesn't specify how integers get
1004 converted to pointers; usually, the ABI doesn't either, but
1005 ABI-specific code is a more reasonable place to handle it. */
1007 if (TYPE_CODE (value_type (val
)) != TYPE_CODE_PTR
1008 && TYPE_CODE (value_type (val
)) != TYPE_CODE_REF
1009 && gdbarch_integer_to_address_p (current_gdbarch
))
1010 return gdbarch_integer_to_address (current_gdbarch
, value_type (val
),
1011 value_contents (val
));
1013 return unpack_long (value_type (val
), value_contents (val
));
1017 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
1018 as a long, or as a double, assuming the raw data is described
1019 by type TYPE. Knows how to convert different sizes of values
1020 and can convert between fixed and floating point. We don't assume
1021 any alignment for the raw data. Return value is in host byte order.
1023 If you want functions and arrays to be coerced to pointers, and
1024 references to be dereferenced, call value_as_long() instead.
1026 C++: It is assumed that the front-end has taken care of
1027 all matters concerning pointers to members. A pointer
1028 to member which reaches here is considered to be equivalent
1029 to an INT (or some size). After all, it is only an offset. */
1032 unpack_long (struct type
*type
, const gdb_byte
*valaddr
)
1034 enum type_code code
= TYPE_CODE (type
);
1035 int len
= TYPE_LENGTH (type
);
1036 int nosign
= TYPE_UNSIGNED (type
);
1038 if (current_language
->la_language
== language_scm
1039 && is_scmvalue_type (type
))
1040 return scm_unpack (type
, valaddr
, TYPE_CODE_INT
);
1044 case TYPE_CODE_TYPEDEF
:
1045 return unpack_long (check_typedef (type
), valaddr
);
1046 case TYPE_CODE_ENUM
:
1047 case TYPE_CODE_FLAGS
:
1048 case TYPE_CODE_BOOL
:
1050 case TYPE_CODE_CHAR
:
1051 case TYPE_CODE_RANGE
:
1053 return extract_unsigned_integer (valaddr
, len
);
1055 return extract_signed_integer (valaddr
, len
);
1058 return extract_typed_floating (valaddr
, type
);
1062 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
1063 whether we want this to be true eventually. */
1064 return extract_typed_address (valaddr
, type
);
1066 case TYPE_CODE_MEMBER
:
1067 error (_("not implemented: member types in unpack_long"));
1070 error (_("Value can't be converted to integer."));
1072 return 0; /* Placate lint. */
1075 /* Return a double value from the specified type and address.
1076 INVP points to an int which is set to 0 for valid value,
1077 1 for invalid value (bad float format). In either case,
1078 the returned double is OK to use. Argument is in target
1079 format, result is in host format. */
1082 unpack_double (struct type
*type
, const gdb_byte
*valaddr
, int *invp
)
1084 enum type_code code
;
1088 *invp
= 0; /* Assume valid. */
1089 CHECK_TYPEDEF (type
);
1090 code
= TYPE_CODE (type
);
1091 len
= TYPE_LENGTH (type
);
1092 nosign
= TYPE_UNSIGNED (type
);
1093 if (code
== TYPE_CODE_FLT
)
1095 /* NOTE: cagney/2002-02-19: There was a test here to see if the
1096 floating-point value was valid (using the macro
1097 INVALID_FLOAT). That test/macro have been removed.
1099 It turns out that only the VAX defined this macro and then
1100 only in a non-portable way. Fixing the portability problem
1101 wouldn't help since the VAX floating-point code is also badly
1102 bit-rotten. The target needs to add definitions for the
1103 methods TARGET_FLOAT_FORMAT and TARGET_DOUBLE_FORMAT - these
1104 exactly describe the target floating-point format. The
1105 problem here is that the corresponding floatformat_vax_f and
1106 floatformat_vax_d values these methods should be set to are
1107 also not defined either. Oops!
1109 Hopefully someone will add both the missing floatformat
1110 definitions and the new cases for floatformat_is_valid (). */
1112 if (!floatformat_is_valid (floatformat_from_type (type
), valaddr
))
1118 return extract_typed_floating (valaddr
, type
);
1122 /* Unsigned -- be sure we compensate for signed LONGEST. */
1123 return (ULONGEST
) unpack_long (type
, valaddr
);
1127 /* Signed -- we are OK with unpack_long. */
1128 return unpack_long (type
, valaddr
);
1132 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
1133 as a CORE_ADDR, assuming the raw data is described by type TYPE.
1134 We don't assume any alignment for the raw data. Return value is in
1137 If you want functions and arrays to be coerced to pointers, and
1138 references to be dereferenced, call value_as_address() instead.
1140 C++: It is assumed that the front-end has taken care of
1141 all matters concerning pointers to members. A pointer
1142 to member which reaches here is considered to be equivalent
1143 to an INT (or some size). After all, it is only an offset. */
1146 unpack_pointer (struct type
*type
, const gdb_byte
*valaddr
)
1148 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
1149 whether we want this to be true eventually. */
1150 return unpack_long (type
, valaddr
);
1154 /* Get the value of the FIELDN'th field (which must be static) of
1155 TYPE. Return NULL if the field doesn't exist or has been
1159 value_static_field (struct type
*type
, int fieldno
)
1161 struct value
*retval
;
1163 if (TYPE_FIELD_STATIC_HAS_ADDR (type
, fieldno
))
1165 retval
= value_at (TYPE_FIELD_TYPE (type
, fieldno
),
1166 TYPE_FIELD_STATIC_PHYSADDR (type
, fieldno
));
1170 char *phys_name
= TYPE_FIELD_STATIC_PHYSNAME (type
, fieldno
);
1171 struct symbol
*sym
= lookup_symbol (phys_name
, 0, VAR_DOMAIN
, 0, NULL
);
1174 /* With some compilers, e.g. HP aCC, static data members are reported
1175 as non-debuggable symbols */
1176 struct minimal_symbol
*msym
= lookup_minimal_symbol (phys_name
, NULL
, NULL
);
1181 retval
= value_at (TYPE_FIELD_TYPE (type
, fieldno
),
1182 SYMBOL_VALUE_ADDRESS (msym
));
1187 /* SYM should never have a SYMBOL_CLASS which will require
1188 read_var_value to use the FRAME parameter. */
1189 if (symbol_read_needs_frame (sym
))
1190 warning (_("static field's value depends on the current "
1191 "frame - bad debug info?"));
1192 retval
= read_var_value (sym
, NULL
);
1194 if (retval
&& VALUE_LVAL (retval
) == lval_memory
)
1195 SET_FIELD_PHYSADDR (TYPE_FIELD (type
, fieldno
),
1196 VALUE_ADDRESS (retval
));
1201 /* Change the enclosing type of a value object VAL to NEW_ENCL_TYPE.
1202 You have to be careful here, since the size of the data area for the value
1203 is set by the length of the enclosing type. So if NEW_ENCL_TYPE is bigger
1204 than the old enclosing type, you have to allocate more space for the data.
1205 The return value is a pointer to the new version of this value structure. */
1208 value_change_enclosing_type (struct value
*val
, struct type
*new_encl_type
)
1210 if (TYPE_LENGTH (new_encl_type
) <= TYPE_LENGTH (value_enclosing_type (val
)))
1212 val
->enclosing_type
= new_encl_type
;
1217 struct value
*new_val
;
1220 new_val
= (struct value
*) xrealloc (val
, sizeof (struct value
) + TYPE_LENGTH (new_encl_type
));
1222 new_val
->enclosing_type
= new_encl_type
;
1224 /* We have to make sure this ends up in the same place in the value
1225 chain as the original copy, so it's clean-up behavior is the same.
1226 If the value has been released, this is a waste of time, but there
1227 is no way to tell that in advance, so... */
1229 if (val
!= all_values
)
1231 for (prev
= all_values
; prev
!= NULL
; prev
= prev
->next
)
1233 if (prev
->next
== val
)
1235 prev
->next
= new_val
;
1245 /* Given a value ARG1 (offset by OFFSET bytes)
1246 of a struct or union type ARG_TYPE,
1247 extract and return the value of one of its (non-static) fields.
1248 FIELDNO says which field. */
1251 value_primitive_field (struct value
*arg1
, int offset
,
1252 int fieldno
, struct type
*arg_type
)
1257 CHECK_TYPEDEF (arg_type
);
1258 type
= TYPE_FIELD_TYPE (arg_type
, fieldno
);
1260 /* Handle packed fields */
1262 if (TYPE_FIELD_BITSIZE (arg_type
, fieldno
))
1264 v
= value_from_longest (type
,
1265 unpack_field_as_long (arg_type
,
1266 value_contents (arg1
)
1269 v
->bitpos
= TYPE_FIELD_BITPOS (arg_type
, fieldno
) % 8;
1270 v
->bitsize
= TYPE_FIELD_BITSIZE (arg_type
, fieldno
);
1271 v
->offset
= value_offset (arg1
) + offset
1272 + TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
1274 else if (fieldno
< TYPE_N_BASECLASSES (arg_type
))
1276 /* This field is actually a base subobject, so preserve the
1277 entire object's contents for later references to virtual
1279 v
= allocate_value (value_enclosing_type (arg1
));
1281 if (value_lazy (arg1
))
1282 set_value_lazy (v
, 1);
1284 memcpy (value_contents_all_raw (v
), value_contents_all_raw (arg1
),
1285 TYPE_LENGTH (value_enclosing_type (arg1
)));
1286 v
->offset
= value_offset (arg1
);
1287 v
->embedded_offset
= (offset
+ value_embedded_offset (arg1
)
1288 + TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8);
1292 /* Plain old data member */
1293 offset
+= TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
1294 v
= allocate_value (type
);
1295 if (value_lazy (arg1
))
1296 set_value_lazy (v
, 1);
1298 memcpy (value_contents_raw (v
),
1299 value_contents_raw (arg1
) + offset
,
1300 TYPE_LENGTH (type
));
1301 v
->offset
= (value_offset (arg1
) + offset
1302 + value_embedded_offset (arg1
));
1304 VALUE_LVAL (v
) = VALUE_LVAL (arg1
);
1305 if (VALUE_LVAL (arg1
) == lval_internalvar
)
1306 VALUE_LVAL (v
) = lval_internalvar_component
;
1307 VALUE_ADDRESS (v
) = VALUE_ADDRESS (arg1
);
1308 VALUE_REGNUM (v
) = VALUE_REGNUM (arg1
);
1309 VALUE_FRAME_ID (v
) = VALUE_FRAME_ID (arg1
);
1310 /* VALUE_OFFSET (v) = VALUE_OFFSET (arg1) + offset
1311 + TYPE_FIELD_BITPOS (arg_type, fieldno) / 8; */
1315 /* Given a value ARG1 of a struct or union type,
1316 extract and return the value of one of its (non-static) fields.
1317 FIELDNO says which field. */
1320 value_field (struct value
*arg1
, int fieldno
)
1322 return value_primitive_field (arg1
, 0, fieldno
, value_type (arg1
));
1325 /* Return a non-virtual function as a value.
1326 F is the list of member functions which contains the desired method.
1327 J is an index into F which provides the desired method.
1329 We only use the symbol for its address, so be happy with either a
1330 full symbol or a minimal symbol.
1334 value_fn_field (struct value
**arg1p
, struct fn_field
*f
, int j
, struct type
*type
,
1338 struct type
*ftype
= TYPE_FN_FIELD_TYPE (f
, j
);
1339 char *physname
= TYPE_FN_FIELD_PHYSNAME (f
, j
);
1341 struct minimal_symbol
*msym
;
1343 sym
= lookup_symbol (physname
, 0, VAR_DOMAIN
, 0, NULL
);
1350 gdb_assert (sym
== NULL
);
1351 msym
= lookup_minimal_symbol (physname
, NULL
, NULL
);
1356 v
= allocate_value (ftype
);
1359 VALUE_ADDRESS (v
) = BLOCK_START (SYMBOL_BLOCK_VALUE (sym
));
1363 VALUE_ADDRESS (v
) = SYMBOL_VALUE_ADDRESS (msym
);
1368 if (type
!= value_type (*arg1p
))
1369 *arg1p
= value_ind (value_cast (lookup_pointer_type (type
),
1370 value_addr (*arg1p
)));
1372 /* Move the `this' pointer according to the offset.
1373 VALUE_OFFSET (*arg1p) += offset;
1381 /* Unpack a field FIELDNO of the specified TYPE, from the anonymous object at
1384 Extracting bits depends on endianness of the machine. Compute the
1385 number of least significant bits to discard. For big endian machines,
1386 we compute the total number of bits in the anonymous object, subtract
1387 off the bit count from the MSB of the object to the MSB of the
1388 bitfield, then the size of the bitfield, which leaves the LSB discard
1389 count. For little endian machines, the discard count is simply the
1390 number of bits from the LSB of the anonymous object to the LSB of the
1393 If the field is signed, we also do sign extension. */
1396 unpack_field_as_long (struct type
*type
, const gdb_byte
*valaddr
, int fieldno
)
1400 int bitpos
= TYPE_FIELD_BITPOS (type
, fieldno
);
1401 int bitsize
= TYPE_FIELD_BITSIZE (type
, fieldno
);
1403 struct type
*field_type
;
1405 val
= extract_unsigned_integer (valaddr
+ bitpos
/ 8, sizeof (val
));
1406 field_type
= TYPE_FIELD_TYPE (type
, fieldno
);
1407 CHECK_TYPEDEF (field_type
);
1409 /* Extract bits. See comment above. */
1411 if (BITS_BIG_ENDIAN
)
1412 lsbcount
= (sizeof val
* 8 - bitpos
% 8 - bitsize
);
1414 lsbcount
= (bitpos
% 8);
1417 /* If the field does not entirely fill a LONGEST, then zero the sign bits.
1418 If the field is signed, and is negative, then sign extend. */
1420 if ((bitsize
> 0) && (bitsize
< 8 * (int) sizeof (val
)))
1422 valmask
= (((ULONGEST
) 1) << bitsize
) - 1;
1424 if (!TYPE_UNSIGNED (field_type
))
1426 if (val
& (valmask
^ (valmask
>> 1)))
1435 /* Modify the value of a bitfield. ADDR points to a block of memory in
1436 target byte order; the bitfield starts in the byte pointed to. FIELDVAL
1437 is the desired value of the field, in host byte order. BITPOS and BITSIZE
1438 indicate which bits (in target bit order) comprise the bitfield.
1439 Requires 0 < BITSIZE <= lbits, 0 <= BITPOS+BITSIZE <= lbits, and
1440 0 <= BITPOS, where lbits is the size of a LONGEST in bits. */
1443 modify_field (gdb_byte
*addr
, LONGEST fieldval
, int bitpos
, int bitsize
)
1446 ULONGEST mask
= (ULONGEST
) -1 >> (8 * sizeof (ULONGEST
) - bitsize
);
1448 /* If a negative fieldval fits in the field in question, chop
1449 off the sign extension bits. */
1450 if ((~fieldval
& ~(mask
>> 1)) == 0)
1453 /* Warn if value is too big to fit in the field in question. */
1454 if (0 != (fieldval
& ~mask
))
1456 /* FIXME: would like to include fieldval in the message, but
1457 we don't have a sprintf_longest. */
1458 warning (_("Value does not fit in %d bits."), bitsize
);
1460 /* Truncate it, otherwise adjoining fields may be corrupted. */
1464 oword
= extract_unsigned_integer (addr
, sizeof oword
);
1466 /* Shifting for bit field depends on endianness of the target machine. */
1467 if (BITS_BIG_ENDIAN
)
1468 bitpos
= sizeof (oword
) * 8 - bitpos
- bitsize
;
1470 oword
&= ~(mask
<< bitpos
);
1471 oword
|= fieldval
<< bitpos
;
1473 store_unsigned_integer (addr
, sizeof oword
, oword
);
1476 /* Convert C numbers into newly allocated values */
1479 value_from_longest (struct type
*type
, LONGEST num
)
1481 struct value
*val
= allocate_value (type
);
1482 enum type_code code
;
1485 code
= TYPE_CODE (type
);
1486 len
= TYPE_LENGTH (type
);
1490 case TYPE_CODE_TYPEDEF
:
1491 type
= check_typedef (type
);
1494 case TYPE_CODE_CHAR
:
1495 case TYPE_CODE_ENUM
:
1496 case TYPE_CODE_FLAGS
:
1497 case TYPE_CODE_BOOL
:
1498 case TYPE_CODE_RANGE
:
1499 store_signed_integer (value_contents_raw (val
), len
, num
);
1504 store_typed_address (value_contents_raw (val
), type
, (CORE_ADDR
) num
);
1508 error (_("Unexpected type (%d) encountered for integer constant."), code
);
1514 /* Create a value representing a pointer of type TYPE to the address
1517 value_from_pointer (struct type
*type
, CORE_ADDR addr
)
1519 struct value
*val
= allocate_value (type
);
1520 store_typed_address (value_contents_raw (val
), type
, addr
);
1525 /* Create a value for a string constant to be stored locally
1526 (not in the inferior's memory space, but in GDB memory).
1527 This is analogous to value_from_longest, which also does not
1528 use inferior memory. String shall NOT contain embedded nulls. */
1531 value_from_string (char *ptr
)
1534 int len
= strlen (ptr
);
1535 int lowbound
= current_language
->string_lower_bound
;
1536 struct type
*string_char_type
;
1537 struct type
*rangetype
;
1538 struct type
*stringtype
;
1540 rangetype
= create_range_type ((struct type
*) NULL
,
1542 lowbound
, len
+ lowbound
- 1);
1543 string_char_type
= language_string_char_type (current_language
,
1545 stringtype
= create_array_type ((struct type
*) NULL
,
1548 val
= allocate_value (stringtype
);
1549 memcpy (value_contents_raw (val
), ptr
, len
);
1554 value_from_double (struct type
*type
, DOUBLEST num
)
1556 struct value
*val
= allocate_value (type
);
1557 struct type
*base_type
= check_typedef (type
);
1558 enum type_code code
= TYPE_CODE (base_type
);
1559 int len
= TYPE_LENGTH (base_type
);
1561 if (code
== TYPE_CODE_FLT
)
1563 store_typed_floating (value_contents_raw (val
), base_type
, num
);
1566 error (_("Unexpected type encountered for floating constant."));
1572 coerce_ref (struct value
*arg
)
1574 struct type
*value_type_arg_tmp
= check_typedef (value_type (arg
));
1575 if (TYPE_CODE (value_type_arg_tmp
) == TYPE_CODE_REF
)
1576 arg
= value_at_lazy (TYPE_TARGET_TYPE (value_type_arg_tmp
),
1577 unpack_pointer (value_type (arg
),
1578 value_contents (arg
)));
1583 coerce_array (struct value
*arg
)
1585 arg
= coerce_ref (arg
);
1586 if (current_language
->c_style_arrays
1587 && TYPE_CODE (value_type (arg
)) == TYPE_CODE_ARRAY
)
1588 arg
= value_coerce_array (arg
);
1589 if (TYPE_CODE (value_type (arg
)) == TYPE_CODE_FUNC
)
1590 arg
= value_coerce_function (arg
);
1595 coerce_number (struct value
*arg
)
1597 arg
= coerce_array (arg
);
1598 arg
= coerce_enum (arg
);
1603 coerce_enum (struct value
*arg
)
1605 if (TYPE_CODE (check_typedef (value_type (arg
))) == TYPE_CODE_ENUM
)
1606 arg
= value_cast (builtin_type_unsigned_int
, arg
);
1611 /* Should we use DEPRECATED_EXTRACT_STRUCT_VALUE_ADDRESS instead of
1612 EXTRACT_RETURN_VALUE? GCC_P is true if compiled with gcc and TYPE
1613 is the type (which is known to be struct, union or array).
1615 On most machines, the struct convention is used unless we are
1616 using gcc and the type is of a special size. */
1617 /* As of about 31 Mar 93, GCC was changed to be compatible with the
1618 native compiler. GCC 2.3.3 was the last release that did it the
1619 old way. Since gcc2_compiled was not changed, we have no
1620 way to correctly win in all cases, so we just do the right thing
1621 for gcc1 and for gcc2 after this change. Thus it loses for gcc
1622 2.0-2.3.3. This is somewhat unfortunate, but changing gcc2_compiled
1623 would cause more chaos than dealing with some struct returns being
1625 /* NOTE: cagney/2004-06-13: Deleted check for "gcc_p". GCC 1.x is
1629 generic_use_struct_convention (int gcc_p
, struct type
*value_type
)
1631 return !(TYPE_LENGTH (value_type
) == 1
1632 || TYPE_LENGTH (value_type
) == 2
1633 || TYPE_LENGTH (value_type
) == 4
1634 || TYPE_LENGTH (value_type
) == 8);
1637 /* Return true if the function returning the specified type is using
1638 the convention of returning structures in memory (passing in the
1639 address as a hidden first parameter). GCC_P is nonzero if compiled
1643 using_struct_return (struct type
*value_type
, int gcc_p
)
1645 enum type_code code
= TYPE_CODE (value_type
);
1647 if (code
== TYPE_CODE_ERROR
)
1648 error (_("Function return type unknown."));
1650 if (code
== TYPE_CODE_VOID
)
1651 /* A void return value is never in memory. See also corresponding
1652 code in "print_return_value". */
1655 /* Probe the architecture for the return-value convention. */
1656 return (gdbarch_return_value (current_gdbarch
, value_type
,
1658 != RETURN_VALUE_REGISTER_CONVENTION
);
1662 _initialize_values (void)
1664 add_cmd ("convenience", no_class
, show_convenience
, _("\
1665 Debugger convenience (\"$foo\") variables.\n\
1666 These variables are created when you assign them values;\n\
1667 thus, \"print $foo=1\" gives \"$foo\" the value 1. Values may be any type.\n\
1669 A few convenience variables are given values automatically:\n\
1670 \"$_\"holds the last address examined with \"x\" or \"info lines\",\n\
1671 \"$__\" holds the contents of the last address examined with \"x\"."),
1674 add_cmd ("values", no_class
, show_values
,
1675 _("Elements of value history around item number IDX (or last ten)."),
1678 add_com ("init-if-undefined", class_vars
, init_if_undefined_command
, _("\
1679 Initialize a convenience variable if necessary.\n\
1680 init-if-undefined VARIABLE = EXPRESSION\n\
1681 Set an internal VARIABLE to the result of the EXPRESSION if it does not\n\
1682 exist or does not contain a value. The EXPRESSION is not evaluated if the\n\
1683 VARIABLE is already initialized."));