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_type (struct value
*value
)
133 value_offset (struct value
*value
)
135 return value
->offset
;
139 value_bitpos (struct value
*value
)
141 return value
->bitpos
;
145 value_bitsize (struct value
*value
)
147 return value
->bitsize
;
151 value_contents_raw (struct value
*value
)
153 return value
->aligner
.contents
+ value
->embedded_offset
;
157 value_contents_all_raw (struct value
*value
)
159 return value
->aligner
.contents
;
163 value_enclosing_type (struct value
*value
)
165 return value
->enclosing_type
;
169 value_contents_all (struct value
*value
)
172 value_fetch_lazy (value
);
173 return value
->aligner
.contents
;
177 value_lazy (struct value
*value
)
183 set_value_lazy (struct value
*value
, int val
)
189 value_contents (struct value
*value
)
191 return value_contents_writeable (value
);
195 value_contents_writeable (struct value
*value
)
198 value_fetch_lazy (value
);
199 return value
->aligner
.contents
;
203 value_optimized_out (struct value
*value
)
205 return value
->optimized_out
;
209 set_value_optimized_out (struct value
*value
, int val
)
211 value
->optimized_out
= val
;
215 value_embedded_offset (struct value
*value
)
217 return value
->embedded_offset
;
221 set_value_embedded_offset (struct value
*value
, int val
)
223 value
->embedded_offset
= val
;
227 value_pointed_to_offset (struct value
*value
)
229 return value
->pointed_to_offset
;
233 set_value_pointed_to_offset (struct value
*value
, int val
)
235 value
->pointed_to_offset
= val
;
239 deprecated_value_lval_hack (struct value
*value
)
245 deprecated_value_address_hack (struct value
*value
)
247 return &value
->location
.address
;
250 struct internalvar
**
251 deprecated_value_internalvar_hack (struct value
*value
)
253 return &value
->location
.internalvar
;
257 deprecated_value_frame_id_hack (struct value
*value
)
259 return &value
->frame_id
;
263 deprecated_value_regnum_hack (struct value
*value
)
265 return &value
->regnum
;
268 /* Return a mark in the value chain. All values allocated after the
269 mark is obtained (except for those released) are subject to being freed
270 if a subsequent value_free_to_mark is passed the mark. */
277 /* Free all values allocated since MARK was obtained by value_mark
278 (except for those released). */
280 value_free_to_mark (struct value
*mark
)
285 for (val
= all_values
; val
&& val
!= mark
; val
= next
)
293 /* Free all the values that have been allocated (except for those released).
294 Called after each command, successful or not. */
297 free_all_values (void)
302 for (val
= all_values
; val
; val
= next
)
311 /* Remove VAL from the chain all_values
312 so it will not be freed automatically. */
315 release_value (struct value
*val
)
319 if (all_values
== val
)
321 all_values
= val
->next
;
325 for (v
= all_values
; v
; v
= v
->next
)
335 /* Release all values up to mark */
337 value_release_to_mark (struct value
*mark
)
342 for (val
= next
= all_values
; next
; next
= next
->next
)
343 if (next
->next
== mark
)
345 all_values
= next
->next
;
353 /* Return a copy of the value ARG.
354 It contains the same contents, for same memory address,
355 but it's a different block of storage. */
358 value_copy (struct value
*arg
)
360 struct type
*encl_type
= value_enclosing_type (arg
);
361 struct value
*val
= allocate_value (encl_type
);
362 val
->type
= arg
->type
;
363 VALUE_LVAL (val
) = VALUE_LVAL (arg
);
364 VALUE_ADDRESS (val
) = VALUE_ADDRESS (arg
);
365 val
->offset
= arg
->offset
;
366 val
->bitpos
= arg
->bitpos
;
367 val
->bitsize
= arg
->bitsize
;
368 VALUE_FRAME_ID (val
) = VALUE_FRAME_ID (arg
);
369 VALUE_REGNUM (val
) = VALUE_REGNUM (arg
);
370 val
->lazy
= arg
->lazy
;
371 val
->optimized_out
= arg
->optimized_out
;
372 val
->embedded_offset
= value_embedded_offset (arg
);
373 val
->pointed_to_offset
= arg
->pointed_to_offset
;
374 val
->modifiable
= arg
->modifiable
;
375 if (!value_lazy (val
))
377 memcpy (value_contents_all_raw (val
), value_contents_all_raw (arg
),
378 TYPE_LENGTH (value_enclosing_type (arg
)));
384 /* Access to the value history. */
386 /* Record a new value in the value history.
387 Returns the absolute history index of the entry.
388 Result of -1 indicates the value was not saved; otherwise it is the
389 value history index of this new item. */
392 record_latest_value (struct value
*val
)
396 /* We don't want this value to have anything to do with the inferior anymore.
397 In particular, "set $1 = 50" should not affect the variable from which
398 the value was taken, and fast watchpoints should be able to assume that
399 a value on the value history never changes. */
400 if (value_lazy (val
))
401 value_fetch_lazy (val
);
402 /* We preserve VALUE_LVAL so that the user can find out where it was fetched
403 from. This is a bit dubious, because then *&$1 does not just return $1
404 but the current contents of that location. c'est la vie... */
408 /* Here we treat value_history_count as origin-zero
409 and applying to the value being stored now. */
411 i
= value_history_count
% VALUE_HISTORY_CHUNK
;
414 struct value_history_chunk
*new
415 = (struct value_history_chunk
*)
416 xmalloc (sizeof (struct value_history_chunk
));
417 memset (new->values
, 0, sizeof new->values
);
418 new->next
= value_history_chain
;
419 value_history_chain
= new;
422 value_history_chain
->values
[i
] = val
;
424 /* Now we regard value_history_count as origin-one
425 and applying to the value just stored. */
427 return ++value_history_count
;
430 /* Return a copy of the value in the history with sequence number NUM. */
433 access_value_history (int num
)
435 struct value_history_chunk
*chunk
;
440 absnum
+= value_history_count
;
445 error ("The history is empty.");
447 error ("There is only one value in the history.");
449 error ("History does not go back to $$%d.", -num
);
451 if (absnum
> value_history_count
)
452 error ("History has not yet reached $%d.", absnum
);
456 /* Now absnum is always absolute and origin zero. */
458 chunk
= value_history_chain
;
459 for (i
= (value_history_count
- 1) / VALUE_HISTORY_CHUNK
- absnum
/ VALUE_HISTORY_CHUNK
;
463 return value_copy (chunk
->values
[absnum
% VALUE_HISTORY_CHUNK
]);
466 /* Clear the value history entirely.
467 Must be done when new symbol tables are loaded,
468 because the type pointers become invalid. */
471 clear_value_history (void)
473 struct value_history_chunk
*next
;
477 while (value_history_chain
)
479 for (i
= 0; i
< VALUE_HISTORY_CHUNK
; i
++)
480 if ((val
= value_history_chain
->values
[i
]) != NULL
)
482 next
= value_history_chain
->next
;
483 xfree (value_history_chain
);
484 value_history_chain
= next
;
486 value_history_count
= 0;
490 show_values (char *num_exp
, int from_tty
)
498 /* "info history +" should print from the stored position.
499 "info history <exp>" should print around value number <exp>. */
500 if (num_exp
[0] != '+' || num_exp
[1] != '\0')
501 num
= parse_and_eval_long (num_exp
) - 5;
505 /* "info history" means print the last 10 values. */
506 num
= value_history_count
- 9;
512 for (i
= num
; i
< num
+ 10 && i
<= value_history_count
; i
++)
514 val
= access_value_history (i
);
515 printf_filtered ("$%d = ", i
);
516 value_print (val
, gdb_stdout
, 0, Val_pretty_default
);
517 printf_filtered ("\n");
520 /* The next "info history +" should start after what we just printed. */
523 /* Hitting just return after this command should do the same thing as
524 "info history +". If num_exp is null, this is unnecessary, since
525 "info history +" is not useful after "info history". */
526 if (from_tty
&& num_exp
)
533 /* Internal variables. These are variables within the debugger
534 that hold values assigned by debugger commands.
535 The user refers to them with a '$' prefix
536 that does not appear in the variable names stored internally. */
538 static struct internalvar
*internalvars
;
540 /* Look up an internal variable with name NAME. NAME should not
541 normally include a dollar sign.
543 If the specified internal variable does not exist,
544 one is created, with a void value. */
547 lookup_internalvar (char *name
)
549 struct internalvar
*var
;
551 for (var
= internalvars
; var
; var
= var
->next
)
552 if (strcmp (var
->name
, name
) == 0)
555 var
= (struct internalvar
*) xmalloc (sizeof (struct internalvar
));
556 var
->name
= concat (name
, NULL
);
557 var
->value
= allocate_value (builtin_type_void
);
558 release_value (var
->value
);
559 var
->next
= internalvars
;
565 value_of_internalvar (struct internalvar
*var
)
569 val
= value_copy (var
->value
);
570 if (value_lazy (val
))
571 value_fetch_lazy (val
);
572 VALUE_LVAL (val
) = lval_internalvar
;
573 VALUE_INTERNALVAR (val
) = var
;
578 set_internalvar_component (struct internalvar
*var
, int offset
, int bitpos
,
579 int bitsize
, struct value
*newval
)
581 bfd_byte
*addr
= value_contents_writeable (var
->value
) + offset
;
584 modify_field (addr
, value_as_long (newval
),
587 memcpy (addr
, value_contents (newval
), TYPE_LENGTH (value_type (newval
)));
591 set_internalvar (struct internalvar
*var
, struct value
*val
)
593 struct value
*newval
;
595 newval
= value_copy (val
);
596 newval
->modifiable
= 1;
598 /* Force the value to be fetched from the target now, to avoid problems
599 later when this internalvar is referenced and the target is gone or
601 if (value_lazy (newval
))
602 value_fetch_lazy (newval
);
604 /* Begin code which must not call error(). If var->value points to
605 something free'd, an error() obviously leaves a dangling pointer.
606 But we also get a danling pointer if var->value points to
607 something in the value chain (i.e., before release_value is
608 called), because after the error free_all_values will get called before
612 release_value (newval
);
613 /* End code which must not call error(). */
617 internalvar_name (struct internalvar
*var
)
622 /* Free all internalvars. Done when new symtabs are loaded,
623 because that makes the values invalid. */
626 clear_internalvars (void)
628 struct internalvar
*var
;
633 internalvars
= var
->next
;
641 show_convenience (char *ignore
, int from_tty
)
643 struct internalvar
*var
;
646 for (var
= internalvars
; var
; var
= var
->next
)
652 printf_filtered ("$%s = ", var
->name
);
653 value_print (var
->value
, gdb_stdout
, 0, Val_pretty_default
);
654 printf_filtered ("\n");
657 printf_unfiltered ("No debugger convenience variables now defined.\n\
658 Convenience variables have names starting with \"$\";\n\
659 use \"set\" as in \"set $foo = 5\" to define them.\n");
662 /* Extract a value as a C number (either long or double).
663 Knows how to convert fixed values to double, or
664 floating values to long.
665 Does not deallocate the value. */
668 value_as_long (struct value
*val
)
670 /* This coerces arrays and functions, which is necessary (e.g.
671 in disassemble_command). It also dereferences references, which
672 I suspect is the most logical thing to do. */
673 val
= coerce_array (val
);
674 return unpack_long (value_type (val
), value_contents (val
));
678 value_as_double (struct value
*val
)
683 foo
= unpack_double (value_type (val
), value_contents (val
), &inv
);
685 error ("Invalid floating value found in program.");
688 /* Extract a value as a C pointer. Does not deallocate the value.
689 Note that val's type may not actually be a pointer; value_as_long
690 handles all the cases. */
692 value_as_address (struct value
*val
)
694 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
695 whether we want this to be true eventually. */
697 /* ADDR_BITS_REMOVE is wrong if we are being called for a
698 non-address (e.g. argument to "signal", "info break", etc.), or
699 for pointers to char, in which the low bits *are* significant. */
700 return ADDR_BITS_REMOVE (value_as_long (val
));
703 /* There are several targets (IA-64, PowerPC, and others) which
704 don't represent pointers to functions as simply the address of
705 the function's entry point. For example, on the IA-64, a
706 function pointer points to a two-word descriptor, generated by
707 the linker, which contains the function's entry point, and the
708 value the IA-64 "global pointer" register should have --- to
709 support position-independent code. The linker generates
710 descriptors only for those functions whose addresses are taken.
712 On such targets, it's difficult for GDB to convert an arbitrary
713 function address into a function pointer; it has to either find
714 an existing descriptor for that function, or call malloc and
715 build its own. On some targets, it is impossible for GDB to
716 build a descriptor at all: the descriptor must contain a jump
717 instruction; data memory cannot be executed; and code memory
720 Upon entry to this function, if VAL is a value of type `function'
721 (that is, TYPE_CODE (VALUE_TYPE (val)) == TYPE_CODE_FUNC), then
722 VALUE_ADDRESS (val) is the address of the function. This is what
723 you'll get if you evaluate an expression like `main'. The call
724 to COERCE_ARRAY below actually does all the usual unary
725 conversions, which includes converting values of type `function'
726 to `pointer to function'. This is the challenging conversion
727 discussed above. Then, `unpack_long' will convert that pointer
728 back into an address.
730 So, suppose the user types `disassemble foo' on an architecture
731 with a strange function pointer representation, on which GDB
732 cannot build its own descriptors, and suppose further that `foo'
733 has no linker-built descriptor. The address->pointer conversion
734 will signal an error and prevent the command from running, even
735 though the next step would have been to convert the pointer
736 directly back into the same address.
738 The following shortcut avoids this whole mess. If VAL is a
739 function, just return its address directly. */
740 if (TYPE_CODE (value_type (val
)) == TYPE_CODE_FUNC
741 || TYPE_CODE (value_type (val
)) == TYPE_CODE_METHOD
)
742 return VALUE_ADDRESS (val
);
744 val
= coerce_array (val
);
746 /* Some architectures (e.g. Harvard), map instruction and data
747 addresses onto a single large unified address space. For
748 instance: An architecture may consider a large integer in the
749 range 0x10000000 .. 0x1000ffff to already represent a data
750 addresses (hence not need a pointer to address conversion) while
751 a small integer would still need to be converted integer to
752 pointer to address. Just assume such architectures handle all
753 integer conversions in a single function. */
757 I think INTEGER_TO_ADDRESS is a good idea as proposed --- but we
758 must admonish GDB hackers to make sure its behavior matches the
759 compiler's, whenever possible.
761 In general, I think GDB should evaluate expressions the same way
762 the compiler does. When the user copies an expression out of
763 their source code and hands it to a `print' command, they should
764 get the same value the compiler would have computed. Any
765 deviation from this rule can cause major confusion and annoyance,
766 and needs to be justified carefully. In other words, GDB doesn't
767 really have the freedom to do these conversions in clever and
770 AndrewC pointed out that users aren't complaining about how GDB
771 casts integers to pointers; they are complaining that they can't
772 take an address from a disassembly listing and give it to `x/i'.
773 This is certainly important.
775 Adding an architecture method like integer_to_address() certainly
776 makes it possible for GDB to "get it right" in all circumstances
777 --- the target has complete control over how things get done, so
778 people can Do The Right Thing for their target without breaking
779 anyone else. The standard doesn't specify how integers get
780 converted to pointers; usually, the ABI doesn't either, but
781 ABI-specific code is a more reasonable place to handle it. */
783 if (TYPE_CODE (value_type (val
)) != TYPE_CODE_PTR
784 && TYPE_CODE (value_type (val
)) != TYPE_CODE_REF
785 && gdbarch_integer_to_address_p (current_gdbarch
))
786 return gdbarch_integer_to_address (current_gdbarch
, value_type (val
),
787 value_contents (val
));
789 return unpack_long (value_type (val
), value_contents (val
));
793 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
794 as a long, or as a double, assuming the raw data is described
795 by type TYPE. Knows how to convert different sizes of values
796 and can convert between fixed and floating point. We don't assume
797 any alignment for the raw data. Return value is in host byte order.
799 If you want functions and arrays to be coerced to pointers, and
800 references to be dereferenced, call value_as_long() instead.
802 C++: It is assumed that the front-end has taken care of
803 all matters concerning pointers to members. A pointer
804 to member which reaches here is considered to be equivalent
805 to an INT (or some size). After all, it is only an offset. */
808 unpack_long (struct type
*type
, const char *valaddr
)
810 enum type_code code
= TYPE_CODE (type
);
811 int len
= TYPE_LENGTH (type
);
812 int nosign
= TYPE_UNSIGNED (type
);
814 if (current_language
->la_language
== language_scm
815 && is_scmvalue_type (type
))
816 return scm_unpack (type
, valaddr
, TYPE_CODE_INT
);
820 case TYPE_CODE_TYPEDEF
:
821 return unpack_long (check_typedef (type
), valaddr
);
826 case TYPE_CODE_RANGE
:
828 return extract_unsigned_integer (valaddr
, len
);
830 return extract_signed_integer (valaddr
, len
);
833 return extract_typed_floating (valaddr
, type
);
837 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
838 whether we want this to be true eventually. */
839 return extract_typed_address (valaddr
, type
);
841 case TYPE_CODE_MEMBER
:
842 error ("not implemented: member types in unpack_long");
845 error ("Value can't be converted to integer.");
847 return 0; /* Placate lint. */
850 /* Return a double value from the specified type and address.
851 INVP points to an int which is set to 0 for valid value,
852 1 for invalid value (bad float format). In either case,
853 the returned double is OK to use. Argument is in target
854 format, result is in host format. */
857 unpack_double (struct type
*type
, const char *valaddr
, int *invp
)
863 *invp
= 0; /* Assume valid. */
864 CHECK_TYPEDEF (type
);
865 code
= TYPE_CODE (type
);
866 len
= TYPE_LENGTH (type
);
867 nosign
= TYPE_UNSIGNED (type
);
868 if (code
== TYPE_CODE_FLT
)
870 /* NOTE: cagney/2002-02-19: There was a test here to see if the
871 floating-point value was valid (using the macro
872 INVALID_FLOAT). That test/macro have been removed.
874 It turns out that only the VAX defined this macro and then
875 only in a non-portable way. Fixing the portability problem
876 wouldn't help since the VAX floating-point code is also badly
877 bit-rotten. The target needs to add definitions for the
878 methods TARGET_FLOAT_FORMAT and TARGET_DOUBLE_FORMAT - these
879 exactly describe the target floating-point format. The
880 problem here is that the corresponding floatformat_vax_f and
881 floatformat_vax_d values these methods should be set to are
882 also not defined either. Oops!
884 Hopefully someone will add both the missing floatformat
885 definitions and the new cases for floatformat_is_valid (). */
887 if (!floatformat_is_valid (floatformat_from_type (type
), valaddr
))
893 return extract_typed_floating (valaddr
, type
);
897 /* Unsigned -- be sure we compensate for signed LONGEST. */
898 return (ULONGEST
) unpack_long (type
, valaddr
);
902 /* Signed -- we are OK with unpack_long. */
903 return unpack_long (type
, valaddr
);
907 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
908 as a CORE_ADDR, assuming the raw data is described by type TYPE.
909 We don't assume any alignment for the raw data. Return value is in
912 If you want functions and arrays to be coerced to pointers, and
913 references to be dereferenced, call value_as_address() instead.
915 C++: It is assumed that the front-end has taken care of
916 all matters concerning pointers to members. A pointer
917 to member which reaches here is considered to be equivalent
918 to an INT (or some size). After all, it is only an offset. */
921 unpack_pointer (struct type
*type
, const char *valaddr
)
923 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
924 whether we want this to be true eventually. */
925 return unpack_long (type
, valaddr
);
929 /* Get the value of the FIELDN'th field (which must be static) of
930 TYPE. Return NULL if the field doesn't exist or has been
934 value_static_field (struct type
*type
, int fieldno
)
936 struct value
*retval
;
938 if (TYPE_FIELD_STATIC_HAS_ADDR (type
, fieldno
))
940 retval
= value_at (TYPE_FIELD_TYPE (type
, fieldno
),
941 TYPE_FIELD_STATIC_PHYSADDR (type
, fieldno
));
945 char *phys_name
= TYPE_FIELD_STATIC_PHYSNAME (type
, fieldno
);
946 struct symbol
*sym
= lookup_symbol (phys_name
, 0, VAR_DOMAIN
, 0, NULL
);
949 /* With some compilers, e.g. HP aCC, static data members are reported
950 as non-debuggable symbols */
951 struct minimal_symbol
*msym
= lookup_minimal_symbol (phys_name
, NULL
, NULL
);
956 retval
= value_at (TYPE_FIELD_TYPE (type
, fieldno
),
957 SYMBOL_VALUE_ADDRESS (msym
));
962 /* SYM should never have a SYMBOL_CLASS which will require
963 read_var_value to use the FRAME parameter. */
964 if (symbol_read_needs_frame (sym
))
965 warning ("static field's value depends on the current "
966 "frame - bad debug info?");
967 retval
= read_var_value (sym
, NULL
);
969 if (retval
&& VALUE_LVAL (retval
) == lval_memory
)
970 SET_FIELD_PHYSADDR (TYPE_FIELD (type
, fieldno
),
971 VALUE_ADDRESS (retval
));
976 /* Change the enclosing type of a value object VAL to NEW_ENCL_TYPE.
977 You have to be careful here, since the size of the data area for the value
978 is set by the length of the enclosing type. So if NEW_ENCL_TYPE is bigger
979 than the old enclosing type, you have to allocate more space for the data.
980 The return value is a pointer to the new version of this value structure. */
983 value_change_enclosing_type (struct value
*val
, struct type
*new_encl_type
)
985 if (TYPE_LENGTH (new_encl_type
) <= TYPE_LENGTH (value_enclosing_type (val
)))
987 val
->enclosing_type
= new_encl_type
;
992 struct value
*new_val
;
995 new_val
= (struct value
*) xrealloc (val
, sizeof (struct value
) + TYPE_LENGTH (new_encl_type
));
997 new_val
->enclosing_type
= new_encl_type
;
999 /* We have to make sure this ends up in the same place in the value
1000 chain as the original copy, so it's clean-up behavior is the same.
1001 If the value has been released, this is a waste of time, but there
1002 is no way to tell that in advance, so... */
1004 if (val
!= all_values
)
1006 for (prev
= all_values
; prev
!= NULL
; prev
= prev
->next
)
1008 if (prev
->next
== val
)
1010 prev
->next
= new_val
;
1020 /* Given a value ARG1 (offset by OFFSET bytes)
1021 of a struct or union type ARG_TYPE,
1022 extract and return the value of one of its (non-static) fields.
1023 FIELDNO says which field. */
1026 value_primitive_field (struct value
*arg1
, int offset
,
1027 int fieldno
, struct type
*arg_type
)
1032 CHECK_TYPEDEF (arg_type
);
1033 type
= TYPE_FIELD_TYPE (arg_type
, fieldno
);
1035 /* Handle packed fields */
1037 if (TYPE_FIELD_BITSIZE (arg_type
, fieldno
))
1039 v
= value_from_longest (type
,
1040 unpack_field_as_long (arg_type
,
1041 value_contents (arg1
)
1044 v
->bitpos
= TYPE_FIELD_BITPOS (arg_type
, fieldno
) % 8;
1045 v
->bitsize
= TYPE_FIELD_BITSIZE (arg_type
, fieldno
);
1046 v
->offset
= value_offset (arg1
) + offset
1047 + TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
1049 else if (fieldno
< TYPE_N_BASECLASSES (arg_type
))
1051 /* This field is actually a base subobject, so preserve the
1052 entire object's contents for later references to virtual
1054 v
= allocate_value (value_enclosing_type (arg1
));
1056 if (value_lazy (arg1
))
1057 set_value_lazy (v
, 1);
1059 memcpy (value_contents_all_raw (v
), value_contents_all_raw (arg1
),
1060 TYPE_LENGTH (value_enclosing_type (arg1
)));
1061 v
->offset
= value_offset (arg1
);
1062 v
->embedded_offset
= (offset
+ value_embedded_offset (arg1
)
1063 + TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8);
1067 /* Plain old data member */
1068 offset
+= TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
1069 v
= allocate_value (type
);
1070 if (value_lazy (arg1
))
1071 set_value_lazy (v
, 1);
1073 memcpy (value_contents_raw (v
),
1074 value_contents_raw (arg1
) + offset
,
1075 TYPE_LENGTH (type
));
1076 v
->offset
= (value_offset (arg1
) + offset
1077 + value_embedded_offset (arg1
));
1079 VALUE_LVAL (v
) = VALUE_LVAL (arg1
);
1080 if (VALUE_LVAL (arg1
) == lval_internalvar
)
1081 VALUE_LVAL (v
) = lval_internalvar_component
;
1082 VALUE_ADDRESS (v
) = VALUE_ADDRESS (arg1
);
1083 VALUE_REGNUM (v
) = VALUE_REGNUM (arg1
);
1084 VALUE_FRAME_ID (v
) = VALUE_FRAME_ID (arg1
);
1085 /* VALUE_OFFSET (v) = VALUE_OFFSET (arg1) + offset
1086 + TYPE_FIELD_BITPOS (arg_type, fieldno) / 8; */
1090 /* Given a value ARG1 of a struct or union type,
1091 extract and return the value of one of its (non-static) fields.
1092 FIELDNO says which field. */
1095 value_field (struct value
*arg1
, int fieldno
)
1097 return value_primitive_field (arg1
, 0, fieldno
, value_type (arg1
));
1100 /* Return a non-virtual function as a value.
1101 F is the list of member functions which contains the desired method.
1102 J is an index into F which provides the desired method.
1104 We only use the symbol for its address, so be happy with either a
1105 full symbol or a minimal symbol.
1109 value_fn_field (struct value
**arg1p
, struct fn_field
*f
, int j
, struct type
*type
,
1113 struct type
*ftype
= TYPE_FN_FIELD_TYPE (f
, j
);
1114 char *physname
= TYPE_FN_FIELD_PHYSNAME (f
, j
);
1116 struct minimal_symbol
*msym
;
1118 sym
= lookup_symbol (physname
, 0, VAR_DOMAIN
, 0, NULL
);
1125 gdb_assert (sym
== NULL
);
1126 msym
= lookup_minimal_symbol (physname
, NULL
, NULL
);
1131 v
= allocate_value (ftype
);
1134 VALUE_ADDRESS (v
) = BLOCK_START (SYMBOL_BLOCK_VALUE (sym
));
1138 VALUE_ADDRESS (v
) = SYMBOL_VALUE_ADDRESS (msym
);
1143 if (type
!= value_type (*arg1p
))
1144 *arg1p
= value_ind (value_cast (lookup_pointer_type (type
),
1145 value_addr (*arg1p
)));
1147 /* Move the `this' pointer according to the offset.
1148 VALUE_OFFSET (*arg1p) += offset;
1156 /* Unpack a field FIELDNO of the specified TYPE, from the anonymous object at
1159 Extracting bits depends on endianness of the machine. Compute the
1160 number of least significant bits to discard. For big endian machines,
1161 we compute the total number of bits in the anonymous object, subtract
1162 off the bit count from the MSB of the object to the MSB of the
1163 bitfield, then the size of the bitfield, which leaves the LSB discard
1164 count. For little endian machines, the discard count is simply the
1165 number of bits from the LSB of the anonymous object to the LSB of the
1168 If the field is signed, we also do sign extension. */
1171 unpack_field_as_long (struct type
*type
, const char *valaddr
, int fieldno
)
1175 int bitpos
= TYPE_FIELD_BITPOS (type
, fieldno
);
1176 int bitsize
= TYPE_FIELD_BITSIZE (type
, fieldno
);
1178 struct type
*field_type
;
1180 val
= extract_unsigned_integer (valaddr
+ bitpos
/ 8, sizeof (val
));
1181 field_type
= TYPE_FIELD_TYPE (type
, fieldno
);
1182 CHECK_TYPEDEF (field_type
);
1184 /* Extract bits. See comment above. */
1186 if (BITS_BIG_ENDIAN
)
1187 lsbcount
= (sizeof val
* 8 - bitpos
% 8 - bitsize
);
1189 lsbcount
= (bitpos
% 8);
1192 /* If the field does not entirely fill a LONGEST, then zero the sign bits.
1193 If the field is signed, and is negative, then sign extend. */
1195 if ((bitsize
> 0) && (bitsize
< 8 * (int) sizeof (val
)))
1197 valmask
= (((ULONGEST
) 1) << bitsize
) - 1;
1199 if (!TYPE_UNSIGNED (field_type
))
1201 if (val
& (valmask
^ (valmask
>> 1)))
1210 /* Modify the value of a bitfield. ADDR points to a block of memory in
1211 target byte order; the bitfield starts in the byte pointed to. FIELDVAL
1212 is the desired value of the field, in host byte order. BITPOS and BITSIZE
1213 indicate which bits (in target bit order) comprise the bitfield.
1214 Requires 0 < BITSIZE <= lbits, 0 <= BITPOS+BITSIZE <= lbits, and
1215 0 <= BITPOS, where lbits is the size of a LONGEST in bits. */
1218 modify_field (char *addr
, LONGEST fieldval
, int bitpos
, int bitsize
)
1221 ULONGEST mask
= (ULONGEST
) -1 >> (8 * sizeof (ULONGEST
) - bitsize
);
1223 /* If a negative fieldval fits in the field in question, chop
1224 off the sign extension bits. */
1225 if ((~fieldval
& ~(mask
>> 1)) == 0)
1228 /* Warn if value is too big to fit in the field in question. */
1229 if (0 != (fieldval
& ~mask
))
1231 /* FIXME: would like to include fieldval in the message, but
1232 we don't have a sprintf_longest. */
1233 warning ("Value does not fit in %d bits.", bitsize
);
1235 /* Truncate it, otherwise adjoining fields may be corrupted. */
1239 oword
= extract_unsigned_integer (addr
, sizeof oword
);
1241 /* Shifting for bit field depends on endianness of the target machine. */
1242 if (BITS_BIG_ENDIAN
)
1243 bitpos
= sizeof (oword
) * 8 - bitpos
- bitsize
;
1245 oword
&= ~(mask
<< bitpos
);
1246 oword
|= fieldval
<< bitpos
;
1248 store_unsigned_integer (addr
, sizeof oword
, oword
);
1251 /* Convert C numbers into newly allocated values */
1254 value_from_longest (struct type
*type
, LONGEST num
)
1256 struct value
*val
= allocate_value (type
);
1257 enum type_code code
;
1260 code
= TYPE_CODE (type
);
1261 len
= TYPE_LENGTH (type
);
1265 case TYPE_CODE_TYPEDEF
:
1266 type
= check_typedef (type
);
1269 case TYPE_CODE_CHAR
:
1270 case TYPE_CODE_ENUM
:
1271 case TYPE_CODE_BOOL
:
1272 case TYPE_CODE_RANGE
:
1273 store_signed_integer (value_contents_raw (val
), len
, num
);
1278 store_typed_address (value_contents_raw (val
), type
, (CORE_ADDR
) num
);
1282 error ("Unexpected type (%d) encountered for integer constant.", code
);
1288 /* Create a value representing a pointer of type TYPE to the address
1291 value_from_pointer (struct type
*type
, CORE_ADDR addr
)
1293 struct value
*val
= allocate_value (type
);
1294 store_typed_address (value_contents_raw (val
), type
, addr
);
1299 /* Create a value for a string constant to be stored locally
1300 (not in the inferior's memory space, but in GDB memory).
1301 This is analogous to value_from_longest, which also does not
1302 use inferior memory. String shall NOT contain embedded nulls. */
1305 value_from_string (char *ptr
)
1308 int len
= strlen (ptr
);
1309 int lowbound
= current_language
->string_lower_bound
;
1310 struct type
*string_char_type
;
1311 struct type
*rangetype
;
1312 struct type
*stringtype
;
1314 rangetype
= create_range_type ((struct type
*) NULL
,
1316 lowbound
, len
+ lowbound
- 1);
1317 string_char_type
= language_string_char_type (current_language
,
1319 stringtype
= create_array_type ((struct type
*) NULL
,
1322 val
= allocate_value (stringtype
);
1323 memcpy (value_contents_raw (val
), ptr
, len
);
1328 value_from_double (struct type
*type
, DOUBLEST num
)
1330 struct value
*val
= allocate_value (type
);
1331 struct type
*base_type
= check_typedef (type
);
1332 enum type_code code
= TYPE_CODE (base_type
);
1333 int len
= TYPE_LENGTH (base_type
);
1335 if (code
== TYPE_CODE_FLT
)
1337 store_typed_floating (value_contents_raw (val
), base_type
, num
);
1340 error ("Unexpected type encountered for floating constant.");
1346 coerce_ref (struct value
*arg
)
1348 struct type
*value_type_arg_tmp
= check_typedef (value_type (arg
));
1349 if (TYPE_CODE (value_type_arg_tmp
) == TYPE_CODE_REF
)
1350 arg
= value_at_lazy (TYPE_TARGET_TYPE (value_type_arg_tmp
),
1351 unpack_pointer (value_type (arg
),
1352 value_contents (arg
)));
1357 coerce_array (struct value
*arg
)
1359 arg
= coerce_ref (arg
);
1360 if (current_language
->c_style_arrays
1361 && TYPE_CODE (value_type (arg
)) == TYPE_CODE_ARRAY
)
1362 arg
= value_coerce_array (arg
);
1363 if (TYPE_CODE (value_type (arg
)) == TYPE_CODE_FUNC
)
1364 arg
= value_coerce_function (arg
);
1369 coerce_number (struct value
*arg
)
1371 arg
= coerce_array (arg
);
1372 arg
= coerce_enum (arg
);
1377 coerce_enum (struct value
*arg
)
1379 if (TYPE_CODE (check_typedef (value_type (arg
))) == TYPE_CODE_ENUM
)
1380 arg
= value_cast (builtin_type_unsigned_int
, arg
);
1385 /* Should we use DEPRECATED_EXTRACT_STRUCT_VALUE_ADDRESS instead of
1386 EXTRACT_RETURN_VALUE? GCC_P is true if compiled with gcc and TYPE
1387 is the type (which is known to be struct, union or array).
1389 On most machines, the struct convention is used unless we are
1390 using gcc and the type is of a special size. */
1391 /* As of about 31 Mar 93, GCC was changed to be compatible with the
1392 native compiler. GCC 2.3.3 was the last release that did it the
1393 old way. Since gcc2_compiled was not changed, we have no
1394 way to correctly win in all cases, so we just do the right thing
1395 for gcc1 and for gcc2 after this change. Thus it loses for gcc
1396 2.0-2.3.3. This is somewhat unfortunate, but changing gcc2_compiled
1397 would cause more chaos than dealing with some struct returns being
1399 /* NOTE: cagney/2004-06-13: Deleted check for "gcc_p". GCC 1.x is
1403 generic_use_struct_convention (int gcc_p
, struct type
*value_type
)
1405 return !(TYPE_LENGTH (value_type
) == 1
1406 || TYPE_LENGTH (value_type
) == 2
1407 || TYPE_LENGTH (value_type
) == 4
1408 || TYPE_LENGTH (value_type
) == 8);
1411 /* Return true if the function returning the specified type is using
1412 the convention of returning structures in memory (passing in the
1413 address as a hidden first parameter). GCC_P is nonzero if compiled
1417 using_struct_return (struct type
*value_type
, int gcc_p
)
1419 enum type_code code
= TYPE_CODE (value_type
);
1421 if (code
== TYPE_CODE_ERROR
)
1422 error ("Function return type unknown.");
1424 if (code
== TYPE_CODE_VOID
)
1425 /* A void return value is never in memory. See also corresponding
1426 code in "print_return_value". */
1429 /* Probe the architecture for the return-value convention. */
1430 return (gdbarch_return_value (current_gdbarch
, value_type
,
1432 != RETURN_VALUE_REGISTER_CONVENTION
);
1436 _initialize_values (void)
1438 add_cmd ("convenience", no_class
, show_convenience
,
1439 "Debugger convenience (\"$foo\") variables.\n\
1440 These variables are created when you assign them values;\n\
1441 thus, \"print $foo=1\" gives \"$foo\" the value 1. Values may be any type.\n\n\
1442 A few convenience variables are given values automatically:\n\
1443 \"$_\"holds the last address examined with \"x\" or \"info lines\",\n\
1444 \"$__\" holds the contents of the last address examined with \"x\".",
1447 add_cmd ("values", no_class
, show_values
,
1448 "Elements of value history around item number IDX (or last ten).",