1 /* Low level packing and unpacking of values for GDB, the GNU Debugger.
3 Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
4 1995, 1996, 1997, 1998, 1999, 2000, 2002, 2003, 2004, 2005 Free
5 Software Foundation, Inc.
7 This file is part of GDB.
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 2 of the License, or
12 (at your option) any later version.
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with this program; if not, write to the Free Software
21 Foundation, Inc., 59 Temple Place - Suite 330,
22 Boston, MA 02111-1307, USA. */
25 #include "gdb_string.h"
37 #include "gdb_assert.h"
41 /* Prototypes for exported functions. */
43 void _initialize_values (void);
45 /* Prototypes for local functions. */
47 static void show_values (char *, int);
49 static void show_convenience (char *, int);
52 /* The value-history records all the values printed
53 by print commands during this session. Each chunk
54 records 60 consecutive values. The first chunk on
55 the chain records the most recent values.
56 The total number of values is in value_history_count. */
58 #define VALUE_HISTORY_CHUNK 60
60 struct value_history_chunk
62 struct value_history_chunk
*next
;
63 struct value
*values
[VALUE_HISTORY_CHUNK
];
66 /* Chain of chunks now in use. */
68 static struct value_history_chunk
*value_history_chain
;
70 static int value_history_count
; /* Abs number of last entry stored */
72 /* List of all value objects currently allocated
73 (except for those released by calls to release_value)
74 This is so they can be freed after each command. */
76 static struct value
*all_values
;
78 /* Allocate a value that has the correct length for type TYPE. */
81 allocate_value (struct type
*type
)
84 struct type
*atype
= check_typedef (type
);
86 val
= (struct value
*) xzalloc (sizeof (struct value
) + TYPE_LENGTH (atype
));
87 val
->next
= all_values
;
90 val
->enclosing_type
= type
;
91 VALUE_LVAL (val
) = not_lval
;
92 VALUE_ADDRESS (val
) = 0;
93 VALUE_FRAME_ID (val
) = null_frame_id
;
97 VALUE_REGNUM (val
) = -1;
99 val
->optimized_out
= 0;
100 val
->embedded_offset
= 0;
101 val
->pointed_to_offset
= 0;
106 /* Allocate a value that has the correct length
107 for COUNT repetitions type TYPE. */
110 allocate_repeat_value (struct type
*type
, int count
)
112 int low_bound
= current_language
->string_lower_bound
; /* ??? */
113 /* FIXME-type-allocation: need a way to free this type when we are
115 struct type
*range_type
116 = create_range_type ((struct type
*) NULL
, builtin_type_int
,
117 low_bound
, count
+ low_bound
- 1);
118 /* FIXME-type-allocation: need a way to free this type when we are
120 return allocate_value (create_array_type ((struct type
*) NULL
,
124 /* Accessor methods. */
127 value_next (struct value
*value
)
133 value_type (struct value
*value
)
138 deprecated_set_value_type (struct value
*value
, struct type
*type
)
144 value_offset (struct value
*value
)
146 return value
->offset
;
149 set_value_offset (struct value
*value
, int offset
)
151 value
->offset
= offset
;
155 value_bitpos (struct value
*value
)
157 return value
->bitpos
;
161 value_bitsize (struct value
*value
)
163 return value
->bitsize
;
167 value_contents_raw (struct value
*value
)
169 return value
->aligner
.contents
+ value
->embedded_offset
;
173 value_contents_all_raw (struct value
*value
)
175 return value
->aligner
.contents
;
179 value_enclosing_type (struct value
*value
)
181 return value
->enclosing_type
;
185 value_contents_all (struct value
*value
)
188 value_fetch_lazy (value
);
189 return value
->aligner
.contents
;
193 value_lazy (struct value
*value
)
199 set_value_lazy (struct value
*value
, int val
)
205 value_contents (struct value
*value
)
207 return value_contents_writeable (value
);
211 value_contents_writeable (struct value
*value
)
214 value_fetch_lazy (value
);
215 return value
->aligner
.contents
;
219 value_optimized_out (struct value
*value
)
221 return value
->optimized_out
;
225 set_value_optimized_out (struct value
*value
, int val
)
227 value
->optimized_out
= val
;
231 value_embedded_offset (struct value
*value
)
233 return value
->embedded_offset
;
237 set_value_embedded_offset (struct value
*value
, int val
)
239 value
->embedded_offset
= val
;
243 value_pointed_to_offset (struct value
*value
)
245 return value
->pointed_to_offset
;
249 set_value_pointed_to_offset (struct value
*value
, int val
)
251 value
->pointed_to_offset
= val
;
255 deprecated_value_lval_hack (struct value
*value
)
261 deprecated_value_address_hack (struct value
*value
)
263 return &value
->location
.address
;
266 struct internalvar
**
267 deprecated_value_internalvar_hack (struct value
*value
)
269 return &value
->location
.internalvar
;
273 deprecated_value_frame_id_hack (struct value
*value
)
275 return &value
->frame_id
;
279 deprecated_value_regnum_hack (struct value
*value
)
281 return &value
->regnum
;
285 deprecated_value_modifiable (struct value
*value
)
287 return value
->modifiable
;
290 deprecated_set_value_modifiable (struct value
*value
, int modifiable
)
292 value
->modifiable
= modifiable
;
295 /* Return a mark in the value chain. All values allocated after the
296 mark is obtained (except for those released) are subject to being freed
297 if a subsequent value_free_to_mark is passed the mark. */
304 /* Free all values allocated since MARK was obtained by value_mark
305 (except for those released). */
307 value_free_to_mark (struct value
*mark
)
312 for (val
= all_values
; val
&& val
!= mark
; val
= next
)
320 /* Free all the values that have been allocated (except for those released).
321 Called after each command, successful or not. */
324 free_all_values (void)
329 for (val
= all_values
; val
; val
= next
)
338 /* Remove VAL from the chain all_values
339 so it will not be freed automatically. */
342 release_value (struct value
*val
)
346 if (all_values
== val
)
348 all_values
= val
->next
;
352 for (v
= all_values
; v
; v
= v
->next
)
362 /* Release all values up to mark */
364 value_release_to_mark (struct value
*mark
)
369 for (val
= next
= all_values
; next
; next
= next
->next
)
370 if (next
->next
== mark
)
372 all_values
= next
->next
;
380 /* Return a copy of the value ARG.
381 It contains the same contents, for same memory address,
382 but it's a different block of storage. */
385 value_copy (struct value
*arg
)
387 struct type
*encl_type
= value_enclosing_type (arg
);
388 struct value
*val
= allocate_value (encl_type
);
389 val
->type
= arg
->type
;
390 VALUE_LVAL (val
) = VALUE_LVAL (arg
);
391 VALUE_ADDRESS (val
) = VALUE_ADDRESS (arg
);
392 val
->offset
= arg
->offset
;
393 val
->bitpos
= arg
->bitpos
;
394 val
->bitsize
= arg
->bitsize
;
395 VALUE_FRAME_ID (val
) = VALUE_FRAME_ID (arg
);
396 VALUE_REGNUM (val
) = VALUE_REGNUM (arg
);
397 val
->lazy
= arg
->lazy
;
398 val
->optimized_out
= arg
->optimized_out
;
399 val
->embedded_offset
= value_embedded_offset (arg
);
400 val
->pointed_to_offset
= arg
->pointed_to_offset
;
401 val
->modifiable
= arg
->modifiable
;
402 if (!value_lazy (val
))
404 memcpy (value_contents_all_raw (val
), value_contents_all_raw (arg
),
405 TYPE_LENGTH (value_enclosing_type (arg
)));
411 /* Access to the value history. */
413 /* Record a new value in the value history.
414 Returns the absolute history index of the entry.
415 Result of -1 indicates the value was not saved; otherwise it is the
416 value history index of this new item. */
419 record_latest_value (struct value
*val
)
423 /* We don't want this value to have anything to do with the inferior anymore.
424 In particular, "set $1 = 50" should not affect the variable from which
425 the value was taken, and fast watchpoints should be able to assume that
426 a value on the value history never changes. */
427 if (value_lazy (val
))
428 value_fetch_lazy (val
);
429 /* We preserve VALUE_LVAL so that the user can find out where it was fetched
430 from. This is a bit dubious, because then *&$1 does not just return $1
431 but the current contents of that location. c'est la vie... */
435 /* Here we treat value_history_count as origin-zero
436 and applying to the value being stored now. */
438 i
= value_history_count
% VALUE_HISTORY_CHUNK
;
441 struct value_history_chunk
*new
442 = (struct value_history_chunk
*)
443 xmalloc (sizeof (struct value_history_chunk
));
444 memset (new->values
, 0, sizeof new->values
);
445 new->next
= value_history_chain
;
446 value_history_chain
= new;
449 value_history_chain
->values
[i
] = val
;
451 /* Now we regard value_history_count as origin-one
452 and applying to the value just stored. */
454 return ++value_history_count
;
457 /* Return a copy of the value in the history with sequence number NUM. */
460 access_value_history (int num
)
462 struct value_history_chunk
*chunk
;
467 absnum
+= value_history_count
;
472 error ("The history is empty.");
474 error ("There is only one value in the history.");
476 error ("History does not go back to $$%d.", -num
);
478 if (absnum
> value_history_count
)
479 error ("History has not yet reached $%d.", absnum
);
483 /* Now absnum is always absolute and origin zero. */
485 chunk
= value_history_chain
;
486 for (i
= (value_history_count
- 1) / VALUE_HISTORY_CHUNK
- absnum
/ VALUE_HISTORY_CHUNK
;
490 return value_copy (chunk
->values
[absnum
% VALUE_HISTORY_CHUNK
]);
493 /* Clear the value history entirely.
494 Must be done when new symbol tables are loaded,
495 because the type pointers become invalid. */
498 clear_value_history (void)
500 struct value_history_chunk
*next
;
504 while (value_history_chain
)
506 for (i
= 0; i
< VALUE_HISTORY_CHUNK
; i
++)
507 if ((val
= value_history_chain
->values
[i
]) != NULL
)
509 next
= value_history_chain
->next
;
510 xfree (value_history_chain
);
511 value_history_chain
= next
;
513 value_history_count
= 0;
517 show_values (char *num_exp
, int from_tty
)
525 /* "info history +" should print from the stored position.
526 "info history <exp>" should print around value number <exp>. */
527 if (num_exp
[0] != '+' || num_exp
[1] != '\0')
528 num
= parse_and_eval_long (num_exp
) - 5;
532 /* "info history" means print the last 10 values. */
533 num
= value_history_count
- 9;
539 for (i
= num
; i
< num
+ 10 && i
<= value_history_count
; i
++)
541 val
= access_value_history (i
);
542 printf_filtered ("$%d = ", i
);
543 value_print (val
, gdb_stdout
, 0, Val_pretty_default
);
544 printf_filtered ("\n");
547 /* The next "info history +" should start after what we just printed. */
550 /* Hitting just return after this command should do the same thing as
551 "info history +". If num_exp is null, this is unnecessary, since
552 "info history +" is not useful after "info history". */
553 if (from_tty
&& num_exp
)
560 /* Internal variables. These are variables within the debugger
561 that hold values assigned by debugger commands.
562 The user refers to them with a '$' prefix
563 that does not appear in the variable names stored internally. */
565 static struct internalvar
*internalvars
;
567 /* Look up an internal variable with name NAME. NAME should not
568 normally include a dollar sign.
570 If the specified internal variable does not exist,
571 one is created, with a void value. */
574 lookup_internalvar (char *name
)
576 struct internalvar
*var
;
578 for (var
= internalvars
; var
; var
= var
->next
)
579 if (strcmp (var
->name
, name
) == 0)
582 var
= (struct internalvar
*) xmalloc (sizeof (struct internalvar
));
583 var
->name
= concat (name
, NULL
);
584 var
->value
= allocate_value (builtin_type_void
);
585 release_value (var
->value
);
586 var
->next
= internalvars
;
592 value_of_internalvar (struct internalvar
*var
)
596 val
= value_copy (var
->value
);
597 if (value_lazy (val
))
598 value_fetch_lazy (val
);
599 VALUE_LVAL (val
) = lval_internalvar
;
600 VALUE_INTERNALVAR (val
) = var
;
605 set_internalvar_component (struct internalvar
*var
, int offset
, int bitpos
,
606 int bitsize
, struct value
*newval
)
608 bfd_byte
*addr
= value_contents_writeable (var
->value
) + offset
;
611 modify_field (addr
, value_as_long (newval
),
614 memcpy (addr
, value_contents (newval
), TYPE_LENGTH (value_type (newval
)));
618 set_internalvar (struct internalvar
*var
, struct value
*val
)
620 struct value
*newval
;
622 newval
= value_copy (val
);
623 newval
->modifiable
= 1;
625 /* Force the value to be fetched from the target now, to avoid problems
626 later when this internalvar is referenced and the target is gone or
628 if (value_lazy (newval
))
629 value_fetch_lazy (newval
);
631 /* Begin code which must not call error(). If var->value points to
632 something free'd, an error() obviously leaves a dangling pointer.
633 But we also get a danling pointer if var->value points to
634 something in the value chain (i.e., before release_value is
635 called), because after the error free_all_values will get called before
639 release_value (newval
);
640 /* End code which must not call error(). */
644 internalvar_name (struct internalvar
*var
)
649 /* Free all internalvars. Done when new symtabs are loaded,
650 because that makes the values invalid. */
653 clear_internalvars (void)
655 struct internalvar
*var
;
660 internalvars
= var
->next
;
668 show_convenience (char *ignore
, int from_tty
)
670 struct internalvar
*var
;
673 for (var
= internalvars
; var
; var
= var
->next
)
679 printf_filtered ("$%s = ", var
->name
);
680 value_print (var
->value
, gdb_stdout
, 0, Val_pretty_default
);
681 printf_filtered ("\n");
684 printf_unfiltered ("No debugger convenience variables now defined.\n\
685 Convenience variables have names starting with \"$\";\n\
686 use \"set\" as in \"set $foo = 5\" to define them.\n");
689 /* Extract a value as a C number (either long or double).
690 Knows how to convert fixed values to double, or
691 floating values to long.
692 Does not deallocate the value. */
695 value_as_long (struct value
*val
)
697 /* This coerces arrays and functions, which is necessary (e.g.
698 in disassemble_command). It also dereferences references, which
699 I suspect is the most logical thing to do. */
700 val
= coerce_array (val
);
701 return unpack_long (value_type (val
), value_contents (val
));
705 value_as_double (struct value
*val
)
710 foo
= unpack_double (value_type (val
), value_contents (val
), &inv
);
712 error ("Invalid floating value found in program.");
715 /* Extract a value as a C pointer. Does not deallocate the value.
716 Note that val's type may not actually be a pointer; value_as_long
717 handles all the cases. */
719 value_as_address (struct value
*val
)
721 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
722 whether we want this to be true eventually. */
724 /* ADDR_BITS_REMOVE is wrong if we are being called for a
725 non-address (e.g. argument to "signal", "info break", etc.), or
726 for pointers to char, in which the low bits *are* significant. */
727 return ADDR_BITS_REMOVE (value_as_long (val
));
730 /* There are several targets (IA-64, PowerPC, and others) which
731 don't represent pointers to functions as simply the address of
732 the function's entry point. For example, on the IA-64, a
733 function pointer points to a two-word descriptor, generated by
734 the linker, which contains the function's entry point, and the
735 value the IA-64 "global pointer" register should have --- to
736 support position-independent code. The linker generates
737 descriptors only for those functions whose addresses are taken.
739 On such targets, it's difficult for GDB to convert an arbitrary
740 function address into a function pointer; it has to either find
741 an existing descriptor for that function, or call malloc and
742 build its own. On some targets, it is impossible for GDB to
743 build a descriptor at all: the descriptor must contain a jump
744 instruction; data memory cannot be executed; and code memory
747 Upon entry to this function, if VAL is a value of type `function'
748 (that is, TYPE_CODE (VALUE_TYPE (val)) == TYPE_CODE_FUNC), then
749 VALUE_ADDRESS (val) is the address of the function. This is what
750 you'll get if you evaluate an expression like `main'. The call
751 to COERCE_ARRAY below actually does all the usual unary
752 conversions, which includes converting values of type `function'
753 to `pointer to function'. This is the challenging conversion
754 discussed above. Then, `unpack_long' will convert that pointer
755 back into an address.
757 So, suppose the user types `disassemble foo' on an architecture
758 with a strange function pointer representation, on which GDB
759 cannot build its own descriptors, and suppose further that `foo'
760 has no linker-built descriptor. The address->pointer conversion
761 will signal an error and prevent the command from running, even
762 though the next step would have been to convert the pointer
763 directly back into the same address.
765 The following shortcut avoids this whole mess. If VAL is a
766 function, just return its address directly. */
767 if (TYPE_CODE (value_type (val
)) == TYPE_CODE_FUNC
768 || TYPE_CODE (value_type (val
)) == TYPE_CODE_METHOD
)
769 return VALUE_ADDRESS (val
);
771 val
= coerce_array (val
);
773 /* Some architectures (e.g. Harvard), map instruction and data
774 addresses onto a single large unified address space. For
775 instance: An architecture may consider a large integer in the
776 range 0x10000000 .. 0x1000ffff to already represent a data
777 addresses (hence not need a pointer to address conversion) while
778 a small integer would still need to be converted integer to
779 pointer to address. Just assume such architectures handle all
780 integer conversions in a single function. */
784 I think INTEGER_TO_ADDRESS is a good idea as proposed --- but we
785 must admonish GDB hackers to make sure its behavior matches the
786 compiler's, whenever possible.
788 In general, I think GDB should evaluate expressions the same way
789 the compiler does. When the user copies an expression out of
790 their source code and hands it to a `print' command, they should
791 get the same value the compiler would have computed. Any
792 deviation from this rule can cause major confusion and annoyance,
793 and needs to be justified carefully. In other words, GDB doesn't
794 really have the freedom to do these conversions in clever and
797 AndrewC pointed out that users aren't complaining about how GDB
798 casts integers to pointers; they are complaining that they can't
799 take an address from a disassembly listing and give it to `x/i'.
800 This is certainly important.
802 Adding an architecture method like integer_to_address() certainly
803 makes it possible for GDB to "get it right" in all circumstances
804 --- the target has complete control over how things get done, so
805 people can Do The Right Thing for their target without breaking
806 anyone else. The standard doesn't specify how integers get
807 converted to pointers; usually, the ABI doesn't either, but
808 ABI-specific code is a more reasonable place to handle it. */
810 if (TYPE_CODE (value_type (val
)) != TYPE_CODE_PTR
811 && TYPE_CODE (value_type (val
)) != TYPE_CODE_REF
812 && gdbarch_integer_to_address_p (current_gdbarch
))
813 return gdbarch_integer_to_address (current_gdbarch
, value_type (val
),
814 value_contents (val
));
816 return unpack_long (value_type (val
), value_contents (val
));
820 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
821 as a long, or as a double, assuming the raw data is described
822 by type TYPE. Knows how to convert different sizes of values
823 and can convert between fixed and floating point. We don't assume
824 any alignment for the raw data. Return value is in host byte order.
826 If you want functions and arrays to be coerced to pointers, and
827 references to be dereferenced, call value_as_long() instead.
829 C++: It is assumed that the front-end has taken care of
830 all matters concerning pointers to members. A pointer
831 to member which reaches here is considered to be equivalent
832 to an INT (or some size). After all, it is only an offset. */
835 unpack_long (struct type
*type
, const char *valaddr
)
837 enum type_code code
= TYPE_CODE (type
);
838 int len
= TYPE_LENGTH (type
);
839 int nosign
= TYPE_UNSIGNED (type
);
841 if (current_language
->la_language
== language_scm
842 && is_scmvalue_type (type
))
843 return scm_unpack (type
, valaddr
, TYPE_CODE_INT
);
847 case TYPE_CODE_TYPEDEF
:
848 return unpack_long (check_typedef (type
), valaddr
);
853 case TYPE_CODE_RANGE
:
855 return extract_unsigned_integer (valaddr
, len
);
857 return extract_signed_integer (valaddr
, len
);
860 return extract_typed_floating (valaddr
, type
);
864 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
865 whether we want this to be true eventually. */
866 return extract_typed_address (valaddr
, type
);
868 case TYPE_CODE_MEMBER
:
869 error ("not implemented: member types in unpack_long");
872 error ("Value can't be converted to integer.");
874 return 0; /* Placate lint. */
877 /* Return a double value from the specified type and address.
878 INVP points to an int which is set to 0 for valid value,
879 1 for invalid value (bad float format). In either case,
880 the returned double is OK to use. Argument is in target
881 format, result is in host format. */
884 unpack_double (struct type
*type
, const char *valaddr
, int *invp
)
890 *invp
= 0; /* Assume valid. */
891 CHECK_TYPEDEF (type
);
892 code
= TYPE_CODE (type
);
893 len
= TYPE_LENGTH (type
);
894 nosign
= TYPE_UNSIGNED (type
);
895 if (code
== TYPE_CODE_FLT
)
897 /* NOTE: cagney/2002-02-19: There was a test here to see if the
898 floating-point value was valid (using the macro
899 INVALID_FLOAT). That test/macro have been removed.
901 It turns out that only the VAX defined this macro and then
902 only in a non-portable way. Fixing the portability problem
903 wouldn't help since the VAX floating-point code is also badly
904 bit-rotten. The target needs to add definitions for the
905 methods TARGET_FLOAT_FORMAT and TARGET_DOUBLE_FORMAT - these
906 exactly describe the target floating-point format. The
907 problem here is that the corresponding floatformat_vax_f and
908 floatformat_vax_d values these methods should be set to are
909 also not defined either. Oops!
911 Hopefully someone will add both the missing floatformat
912 definitions and the new cases for floatformat_is_valid (). */
914 if (!floatformat_is_valid (floatformat_from_type (type
), valaddr
))
920 return extract_typed_floating (valaddr
, type
);
924 /* Unsigned -- be sure we compensate for signed LONGEST. */
925 return (ULONGEST
) unpack_long (type
, valaddr
);
929 /* Signed -- we are OK with unpack_long. */
930 return unpack_long (type
, valaddr
);
934 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
935 as a CORE_ADDR, assuming the raw data is described by type TYPE.
936 We don't assume any alignment for the raw data. Return value is in
939 If you want functions and arrays to be coerced to pointers, and
940 references to be dereferenced, call value_as_address() instead.
942 C++: It is assumed that the front-end has taken care of
943 all matters concerning pointers to members. A pointer
944 to member which reaches here is considered to be equivalent
945 to an INT (or some size). After all, it is only an offset. */
948 unpack_pointer (struct type
*type
, const char *valaddr
)
950 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
951 whether we want this to be true eventually. */
952 return unpack_long (type
, valaddr
);
956 /* Get the value of the FIELDN'th field (which must be static) of
957 TYPE. Return NULL if the field doesn't exist or has been
961 value_static_field (struct type
*type
, int fieldno
)
963 struct value
*retval
;
965 if (TYPE_FIELD_STATIC_HAS_ADDR (type
, fieldno
))
967 retval
= value_at (TYPE_FIELD_TYPE (type
, fieldno
),
968 TYPE_FIELD_STATIC_PHYSADDR (type
, fieldno
));
972 char *phys_name
= TYPE_FIELD_STATIC_PHYSNAME (type
, fieldno
);
973 struct symbol
*sym
= lookup_symbol (phys_name
, 0, VAR_DOMAIN
, 0, NULL
);
976 /* With some compilers, e.g. HP aCC, static data members are reported
977 as non-debuggable symbols */
978 struct minimal_symbol
*msym
= lookup_minimal_symbol (phys_name
, NULL
, NULL
);
983 retval
= value_at (TYPE_FIELD_TYPE (type
, fieldno
),
984 SYMBOL_VALUE_ADDRESS (msym
));
989 /* SYM should never have a SYMBOL_CLASS which will require
990 read_var_value to use the FRAME parameter. */
991 if (symbol_read_needs_frame (sym
))
992 warning ("static field's value depends on the current "
993 "frame - bad debug info?");
994 retval
= read_var_value (sym
, NULL
);
996 if (retval
&& VALUE_LVAL (retval
) == lval_memory
)
997 SET_FIELD_PHYSADDR (TYPE_FIELD (type
, fieldno
),
998 VALUE_ADDRESS (retval
));
1003 /* Change the enclosing type of a value object VAL to NEW_ENCL_TYPE.
1004 You have to be careful here, since the size of the data area for the value
1005 is set by the length of the enclosing type. So if NEW_ENCL_TYPE is bigger
1006 than the old enclosing type, you have to allocate more space for the data.
1007 The return value is a pointer to the new version of this value structure. */
1010 value_change_enclosing_type (struct value
*val
, struct type
*new_encl_type
)
1012 if (TYPE_LENGTH (new_encl_type
) <= TYPE_LENGTH (value_enclosing_type (val
)))
1014 val
->enclosing_type
= new_encl_type
;
1019 struct value
*new_val
;
1022 new_val
= (struct value
*) xrealloc (val
, sizeof (struct value
) + TYPE_LENGTH (new_encl_type
));
1024 new_val
->enclosing_type
= new_encl_type
;
1026 /* We have to make sure this ends up in the same place in the value
1027 chain as the original copy, so it's clean-up behavior is the same.
1028 If the value has been released, this is a waste of time, but there
1029 is no way to tell that in advance, so... */
1031 if (val
!= all_values
)
1033 for (prev
= all_values
; prev
!= NULL
; prev
= prev
->next
)
1035 if (prev
->next
== val
)
1037 prev
->next
= new_val
;
1047 /* Given a value ARG1 (offset by OFFSET bytes)
1048 of a struct or union type ARG_TYPE,
1049 extract and return the value of one of its (non-static) fields.
1050 FIELDNO says which field. */
1053 value_primitive_field (struct value
*arg1
, int offset
,
1054 int fieldno
, struct type
*arg_type
)
1059 CHECK_TYPEDEF (arg_type
);
1060 type
= TYPE_FIELD_TYPE (arg_type
, fieldno
);
1062 /* Handle packed fields */
1064 if (TYPE_FIELD_BITSIZE (arg_type
, fieldno
))
1066 v
= value_from_longest (type
,
1067 unpack_field_as_long (arg_type
,
1068 value_contents (arg1
)
1071 v
->bitpos
= TYPE_FIELD_BITPOS (arg_type
, fieldno
) % 8;
1072 v
->bitsize
= TYPE_FIELD_BITSIZE (arg_type
, fieldno
);
1073 v
->offset
= value_offset (arg1
) + offset
1074 + TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
1076 else if (fieldno
< TYPE_N_BASECLASSES (arg_type
))
1078 /* This field is actually a base subobject, so preserve the
1079 entire object's contents for later references to virtual
1081 v
= allocate_value (value_enclosing_type (arg1
));
1083 if (value_lazy (arg1
))
1084 set_value_lazy (v
, 1);
1086 memcpy (value_contents_all_raw (v
), value_contents_all_raw (arg1
),
1087 TYPE_LENGTH (value_enclosing_type (arg1
)));
1088 v
->offset
= value_offset (arg1
);
1089 v
->embedded_offset
= (offset
+ value_embedded_offset (arg1
)
1090 + TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8);
1094 /* Plain old data member */
1095 offset
+= TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
1096 v
= allocate_value (type
);
1097 if (value_lazy (arg1
))
1098 set_value_lazy (v
, 1);
1100 memcpy (value_contents_raw (v
),
1101 value_contents_raw (arg1
) + offset
,
1102 TYPE_LENGTH (type
));
1103 v
->offset
= (value_offset (arg1
) + offset
1104 + value_embedded_offset (arg1
));
1106 VALUE_LVAL (v
) = VALUE_LVAL (arg1
);
1107 if (VALUE_LVAL (arg1
) == lval_internalvar
)
1108 VALUE_LVAL (v
) = lval_internalvar_component
;
1109 VALUE_ADDRESS (v
) = VALUE_ADDRESS (arg1
);
1110 VALUE_REGNUM (v
) = VALUE_REGNUM (arg1
);
1111 VALUE_FRAME_ID (v
) = VALUE_FRAME_ID (arg1
);
1112 /* VALUE_OFFSET (v) = VALUE_OFFSET (arg1) + offset
1113 + TYPE_FIELD_BITPOS (arg_type, fieldno) / 8; */
1117 /* Given a value ARG1 of a struct or union type,
1118 extract and return the value of one of its (non-static) fields.
1119 FIELDNO says which field. */
1122 value_field (struct value
*arg1
, int fieldno
)
1124 return value_primitive_field (arg1
, 0, fieldno
, value_type (arg1
));
1127 /* Return a non-virtual function as a value.
1128 F is the list of member functions which contains the desired method.
1129 J is an index into F which provides the desired method.
1131 We only use the symbol for its address, so be happy with either a
1132 full symbol or a minimal symbol.
1136 value_fn_field (struct value
**arg1p
, struct fn_field
*f
, int j
, struct type
*type
,
1140 struct type
*ftype
= TYPE_FN_FIELD_TYPE (f
, j
);
1141 char *physname
= TYPE_FN_FIELD_PHYSNAME (f
, j
);
1143 struct minimal_symbol
*msym
;
1145 sym
= lookup_symbol (physname
, 0, VAR_DOMAIN
, 0, NULL
);
1152 gdb_assert (sym
== NULL
);
1153 msym
= lookup_minimal_symbol (physname
, NULL
, NULL
);
1158 v
= allocate_value (ftype
);
1161 VALUE_ADDRESS (v
) = BLOCK_START (SYMBOL_BLOCK_VALUE (sym
));
1165 VALUE_ADDRESS (v
) = SYMBOL_VALUE_ADDRESS (msym
);
1170 if (type
!= value_type (*arg1p
))
1171 *arg1p
= value_ind (value_cast (lookup_pointer_type (type
),
1172 value_addr (*arg1p
)));
1174 /* Move the `this' pointer according to the offset.
1175 VALUE_OFFSET (*arg1p) += offset;
1183 /* Unpack a field FIELDNO of the specified TYPE, from the anonymous object at
1186 Extracting bits depends on endianness of the machine. Compute the
1187 number of least significant bits to discard. For big endian machines,
1188 we compute the total number of bits in the anonymous object, subtract
1189 off the bit count from the MSB of the object to the MSB of the
1190 bitfield, then the size of the bitfield, which leaves the LSB discard
1191 count. For little endian machines, the discard count is simply the
1192 number of bits from the LSB of the anonymous object to the LSB of the
1195 If the field is signed, we also do sign extension. */
1198 unpack_field_as_long (struct type
*type
, const char *valaddr
, int fieldno
)
1202 int bitpos
= TYPE_FIELD_BITPOS (type
, fieldno
);
1203 int bitsize
= TYPE_FIELD_BITSIZE (type
, fieldno
);
1205 struct type
*field_type
;
1207 val
= extract_unsigned_integer (valaddr
+ bitpos
/ 8, sizeof (val
));
1208 field_type
= TYPE_FIELD_TYPE (type
, fieldno
);
1209 CHECK_TYPEDEF (field_type
);
1211 /* Extract bits. See comment above. */
1213 if (BITS_BIG_ENDIAN
)
1214 lsbcount
= (sizeof val
* 8 - bitpos
% 8 - bitsize
);
1216 lsbcount
= (bitpos
% 8);
1219 /* If the field does not entirely fill a LONGEST, then zero the sign bits.
1220 If the field is signed, and is negative, then sign extend. */
1222 if ((bitsize
> 0) && (bitsize
< 8 * (int) sizeof (val
)))
1224 valmask
= (((ULONGEST
) 1) << bitsize
) - 1;
1226 if (!TYPE_UNSIGNED (field_type
))
1228 if (val
& (valmask
^ (valmask
>> 1)))
1237 /* Modify the value of a bitfield. ADDR points to a block of memory in
1238 target byte order; the bitfield starts in the byte pointed to. FIELDVAL
1239 is the desired value of the field, in host byte order. BITPOS and BITSIZE
1240 indicate which bits (in target bit order) comprise the bitfield.
1241 Requires 0 < BITSIZE <= lbits, 0 <= BITPOS+BITSIZE <= lbits, and
1242 0 <= BITPOS, where lbits is the size of a LONGEST in bits. */
1245 modify_field (char *addr
, LONGEST fieldval
, int bitpos
, int bitsize
)
1248 ULONGEST mask
= (ULONGEST
) -1 >> (8 * sizeof (ULONGEST
) - bitsize
);
1250 /* If a negative fieldval fits in the field in question, chop
1251 off the sign extension bits. */
1252 if ((~fieldval
& ~(mask
>> 1)) == 0)
1255 /* Warn if value is too big to fit in the field in question. */
1256 if (0 != (fieldval
& ~mask
))
1258 /* FIXME: would like to include fieldval in the message, but
1259 we don't have a sprintf_longest. */
1260 warning ("Value does not fit in %d bits.", bitsize
);
1262 /* Truncate it, otherwise adjoining fields may be corrupted. */
1266 oword
= extract_unsigned_integer (addr
, sizeof oword
);
1268 /* Shifting for bit field depends on endianness of the target machine. */
1269 if (BITS_BIG_ENDIAN
)
1270 bitpos
= sizeof (oword
) * 8 - bitpos
- bitsize
;
1272 oword
&= ~(mask
<< bitpos
);
1273 oword
|= fieldval
<< bitpos
;
1275 store_unsigned_integer (addr
, sizeof oword
, oword
);
1278 /* Convert C numbers into newly allocated values */
1281 value_from_longest (struct type
*type
, LONGEST num
)
1283 struct value
*val
= allocate_value (type
);
1284 enum type_code code
;
1287 code
= TYPE_CODE (type
);
1288 len
= TYPE_LENGTH (type
);
1292 case TYPE_CODE_TYPEDEF
:
1293 type
= check_typedef (type
);
1296 case TYPE_CODE_CHAR
:
1297 case TYPE_CODE_ENUM
:
1298 case TYPE_CODE_BOOL
:
1299 case TYPE_CODE_RANGE
:
1300 store_signed_integer (value_contents_raw (val
), len
, num
);
1305 store_typed_address (value_contents_raw (val
), type
, (CORE_ADDR
) num
);
1309 error ("Unexpected type (%d) encountered for integer constant.", code
);
1315 /* Create a value representing a pointer of type TYPE to the address
1318 value_from_pointer (struct type
*type
, CORE_ADDR addr
)
1320 struct value
*val
= allocate_value (type
);
1321 store_typed_address (value_contents_raw (val
), type
, addr
);
1326 /* Create a value for a string constant to be stored locally
1327 (not in the inferior's memory space, but in GDB memory).
1328 This is analogous to value_from_longest, which also does not
1329 use inferior memory. String shall NOT contain embedded nulls. */
1332 value_from_string (char *ptr
)
1335 int len
= strlen (ptr
);
1336 int lowbound
= current_language
->string_lower_bound
;
1337 struct type
*string_char_type
;
1338 struct type
*rangetype
;
1339 struct type
*stringtype
;
1341 rangetype
= create_range_type ((struct type
*) NULL
,
1343 lowbound
, len
+ lowbound
- 1);
1344 string_char_type
= language_string_char_type (current_language
,
1346 stringtype
= create_array_type ((struct type
*) NULL
,
1349 val
= allocate_value (stringtype
);
1350 memcpy (value_contents_raw (val
), ptr
, len
);
1355 value_from_double (struct type
*type
, DOUBLEST num
)
1357 struct value
*val
= allocate_value (type
);
1358 struct type
*base_type
= check_typedef (type
);
1359 enum type_code code
= TYPE_CODE (base_type
);
1360 int len
= TYPE_LENGTH (base_type
);
1362 if (code
== TYPE_CODE_FLT
)
1364 store_typed_floating (value_contents_raw (val
), base_type
, num
);
1367 error ("Unexpected type encountered for floating constant.");
1373 coerce_ref (struct value
*arg
)
1375 struct type
*value_type_arg_tmp
= check_typedef (value_type (arg
));
1376 if (TYPE_CODE (value_type_arg_tmp
) == TYPE_CODE_REF
)
1377 arg
= value_at_lazy (TYPE_TARGET_TYPE (value_type_arg_tmp
),
1378 unpack_pointer (value_type (arg
),
1379 value_contents (arg
)));
1384 coerce_array (struct value
*arg
)
1386 arg
= coerce_ref (arg
);
1387 if (current_language
->c_style_arrays
1388 && TYPE_CODE (value_type (arg
)) == TYPE_CODE_ARRAY
)
1389 arg
= value_coerce_array (arg
);
1390 if (TYPE_CODE (value_type (arg
)) == TYPE_CODE_FUNC
)
1391 arg
= value_coerce_function (arg
);
1396 coerce_number (struct value
*arg
)
1398 arg
= coerce_array (arg
);
1399 arg
= coerce_enum (arg
);
1404 coerce_enum (struct value
*arg
)
1406 if (TYPE_CODE (check_typedef (value_type (arg
))) == TYPE_CODE_ENUM
)
1407 arg
= value_cast (builtin_type_unsigned_int
, arg
);
1412 /* Should we use DEPRECATED_EXTRACT_STRUCT_VALUE_ADDRESS instead of
1413 EXTRACT_RETURN_VALUE? GCC_P is true if compiled with gcc and TYPE
1414 is the type (which is known to be struct, union or array).
1416 On most machines, the struct convention is used unless we are
1417 using gcc and the type is of a special size. */
1418 /* As of about 31 Mar 93, GCC was changed to be compatible with the
1419 native compiler. GCC 2.3.3 was the last release that did it the
1420 old way. Since gcc2_compiled was not changed, we have no
1421 way to correctly win in all cases, so we just do the right thing
1422 for gcc1 and for gcc2 after this change. Thus it loses for gcc
1423 2.0-2.3.3. This is somewhat unfortunate, but changing gcc2_compiled
1424 would cause more chaos than dealing with some struct returns being
1426 /* NOTE: cagney/2004-06-13: Deleted check for "gcc_p". GCC 1.x is
1430 generic_use_struct_convention (int gcc_p
, struct type
*value_type
)
1432 return !(TYPE_LENGTH (value_type
) == 1
1433 || TYPE_LENGTH (value_type
) == 2
1434 || TYPE_LENGTH (value_type
) == 4
1435 || TYPE_LENGTH (value_type
) == 8);
1438 /* Return true if the function returning the specified type is using
1439 the convention of returning structures in memory (passing in the
1440 address as a hidden first parameter). GCC_P is nonzero if compiled
1444 using_struct_return (struct type
*value_type
, int gcc_p
)
1446 enum type_code code
= TYPE_CODE (value_type
);
1448 if (code
== TYPE_CODE_ERROR
)
1449 error ("Function return type unknown.");
1451 if (code
== TYPE_CODE_VOID
)
1452 /* A void return value is never in memory. See also corresponding
1453 code in "print_return_value". */
1456 /* Probe the architecture for the return-value convention. */
1457 return (gdbarch_return_value (current_gdbarch
, value_type
,
1459 != RETURN_VALUE_REGISTER_CONVENTION
);
1463 _initialize_values (void)
1465 add_cmd ("convenience", no_class
, show_convenience
,
1466 "Debugger convenience (\"$foo\") variables.\n\
1467 These variables are created when you assign them values;\n\
1468 thus, \"print $foo=1\" gives \"$foo\" the value 1. Values may be any type.\n\n\
1469 A few convenience variables are given values automatically:\n\
1470 \"$_\"holds the last address examined with \"x\" or \"info lines\",\n\
1471 \"$__\" holds the contents of the last address examined with \"x\".",
1474 add_cmd ("values", no_class
, show_values
,
1475 "Elements of value history around item number IDX (or last ten).",