1 /* Low level packing and unpacking of values for GDB, the GNU Debugger.
2 Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995,
3 1996, 1997, 1998, 1999, 2000
4 Free Software Foundation, Inc.
6 This file is part of GDB.
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or
11 (at your option) any later version.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with this program; if not, write to the Free Software
20 Foundation, Inc., 59 Temple Place - Suite 330,
21 Boston, MA 02111-1307, USA. */
24 #include "gdb_string.h"
37 /* Prototypes for exported functions. */
39 void _initialize_values (void);
41 /* Prototypes for local functions. */
43 static value_ptr
value_headof (value_ptr
, struct type
*, struct type
*);
45 static void show_values (char *, int);
47 static void show_convenience (char *, int);
50 /* The value-history records all the values printed
51 by print commands during this session. Each chunk
52 records 60 consecutive values. The first chunk on
53 the chain records the most recent values.
54 The total number of values is in value_history_count. */
56 #define VALUE_HISTORY_CHUNK 60
58 struct value_history_chunk
60 struct value_history_chunk
*next
;
61 value_ptr values
[VALUE_HISTORY_CHUNK
];
64 /* Chain of chunks now in use. */
66 static struct value_history_chunk
*value_history_chain
;
68 static int value_history_count
; /* Abs number of last entry stored */
70 /* List of all value objects currently allocated
71 (except for those released by calls to release_value)
72 This is so they can be freed after each command. */
74 static value_ptr all_values
;
76 /* Allocate a value that has the correct length for type TYPE. */
79 allocate_value (struct type
*type
)
81 register value_ptr val
;
82 struct type
*atype
= check_typedef (type
);
84 val
= (struct value
*) xmalloc (sizeof (struct value
) + TYPE_LENGTH (atype
));
85 VALUE_NEXT (val
) = all_values
;
87 VALUE_TYPE (val
) = type
;
88 VALUE_ENCLOSING_TYPE (val
) = type
;
89 VALUE_LVAL (val
) = not_lval
;
90 VALUE_ADDRESS (val
) = 0;
91 VALUE_FRAME (val
) = 0;
92 VALUE_OFFSET (val
) = 0;
93 VALUE_BITPOS (val
) = 0;
94 VALUE_BITSIZE (val
) = 0;
95 VALUE_REGNO (val
) = -1;
97 VALUE_OPTIMIZED_OUT (val
) = 0;
98 VALUE_BFD_SECTION (val
) = NULL
;
99 VALUE_EMBEDDED_OFFSET (val
) = 0;
100 VALUE_POINTED_TO_OFFSET (val
) = 0;
105 /* Allocate a value that has the correct length
106 for COUNT repetitions type TYPE. */
109 allocate_repeat_value (struct type
*type
, int count
)
111 int low_bound
= current_language
->string_lower_bound
; /* ??? */
112 /* FIXME-type-allocation: need a way to free this type when we are
114 struct type
*range_type
115 = create_range_type ((struct type
*) NULL
, builtin_type_int
,
116 low_bound
, count
+ low_bound
- 1);
117 /* FIXME-type-allocation: need a way to free this type when we are
119 return allocate_value (create_array_type ((struct type
*) NULL
,
123 /* Return a mark in the value chain. All values allocated after the
124 mark is obtained (except for those released) are subject to being freed
125 if a subsequent value_free_to_mark is passed the mark. */
132 /* Free all values allocated since MARK was obtained by value_mark
133 (except for those released). */
135 value_free_to_mark (value_ptr mark
)
139 for (val
= all_values
; val
&& val
!= mark
; val
= next
)
141 next
= VALUE_NEXT (val
);
147 /* Free all the values that have been allocated (except for those released).
148 Called after each command, successful or not. */
151 free_all_values (void)
153 register value_ptr val
, next
;
155 for (val
= all_values
; val
; val
= next
)
157 next
= VALUE_NEXT (val
);
164 /* Remove VAL from the chain all_values
165 so it will not be freed automatically. */
168 release_value (register value_ptr val
)
170 register value_ptr v
;
172 if (all_values
== val
)
174 all_values
= val
->next
;
178 for (v
= all_values
; v
; v
= v
->next
)
188 /* Release all values up to mark */
190 value_release_to_mark (value_ptr mark
)
194 for (val
= next
= all_values
; next
; next
= VALUE_NEXT (next
))
195 if (VALUE_NEXT (next
) == mark
)
197 all_values
= VALUE_NEXT (next
);
198 VALUE_NEXT (next
) = 0;
205 /* Return a copy of the value ARG.
206 It contains the same contents, for same memory address,
207 but it's a different block of storage. */
210 value_copy (value_ptr arg
)
212 register struct type
*encl_type
= VALUE_ENCLOSING_TYPE (arg
);
213 register value_ptr val
= allocate_value (encl_type
);
214 VALUE_TYPE (val
) = VALUE_TYPE (arg
);
215 VALUE_LVAL (val
) = VALUE_LVAL (arg
);
216 VALUE_ADDRESS (val
) = VALUE_ADDRESS (arg
);
217 VALUE_OFFSET (val
) = VALUE_OFFSET (arg
);
218 VALUE_BITPOS (val
) = VALUE_BITPOS (arg
);
219 VALUE_BITSIZE (val
) = VALUE_BITSIZE (arg
);
220 VALUE_FRAME (val
) = VALUE_FRAME (arg
);
221 VALUE_REGNO (val
) = VALUE_REGNO (arg
);
222 VALUE_LAZY (val
) = VALUE_LAZY (arg
);
223 VALUE_OPTIMIZED_OUT (val
) = VALUE_OPTIMIZED_OUT (arg
);
224 VALUE_EMBEDDED_OFFSET (val
) = VALUE_EMBEDDED_OFFSET (arg
);
225 VALUE_POINTED_TO_OFFSET (val
) = VALUE_POINTED_TO_OFFSET (arg
);
226 VALUE_BFD_SECTION (val
) = VALUE_BFD_SECTION (arg
);
227 val
->modifiable
= arg
->modifiable
;
228 if (!VALUE_LAZY (val
))
230 memcpy (VALUE_CONTENTS_ALL_RAW (val
), VALUE_CONTENTS_ALL_RAW (arg
),
231 TYPE_LENGTH (VALUE_ENCLOSING_TYPE (arg
)));
237 /* Access to the value history. */
239 /* Record a new value in the value history.
240 Returns the absolute history index of the entry.
241 Result of -1 indicates the value was not saved; otherwise it is the
242 value history index of this new item. */
245 record_latest_value (value_ptr val
)
249 /* We don't want this value to have anything to do with the inferior anymore.
250 In particular, "set $1 = 50" should not affect the variable from which
251 the value was taken, and fast watchpoints should be able to assume that
252 a value on the value history never changes. */
253 if (VALUE_LAZY (val
))
254 value_fetch_lazy (val
);
255 /* We preserve VALUE_LVAL so that the user can find out where it was fetched
256 from. This is a bit dubious, because then *&$1 does not just return $1
257 but the current contents of that location. c'est la vie... */
261 /* Here we treat value_history_count as origin-zero
262 and applying to the value being stored now. */
264 i
= value_history_count
% VALUE_HISTORY_CHUNK
;
267 register struct value_history_chunk
*new
268 = (struct value_history_chunk
*)
269 xmalloc (sizeof (struct value_history_chunk
));
270 memset (new->values
, 0, sizeof new->values
);
271 new->next
= value_history_chain
;
272 value_history_chain
= new;
275 value_history_chain
->values
[i
] = val
;
277 /* Now we regard value_history_count as origin-one
278 and applying to the value just stored. */
280 return ++value_history_count
;
283 /* Return a copy of the value in the history with sequence number NUM. */
286 access_value_history (int num
)
288 register struct value_history_chunk
*chunk
;
290 register int absnum
= num
;
293 absnum
+= value_history_count
;
298 error ("The history is empty.");
300 error ("There is only one value in the history.");
302 error ("History does not go back to $$%d.", -num
);
304 if (absnum
> value_history_count
)
305 error ("History has not yet reached $%d.", absnum
);
309 /* Now absnum is always absolute and origin zero. */
311 chunk
= value_history_chain
;
312 for (i
= (value_history_count
- 1) / VALUE_HISTORY_CHUNK
- absnum
/ VALUE_HISTORY_CHUNK
;
316 return value_copy (chunk
->values
[absnum
% VALUE_HISTORY_CHUNK
]);
319 /* Clear the value history entirely.
320 Must be done when new symbol tables are loaded,
321 because the type pointers become invalid. */
324 clear_value_history (void)
326 register struct value_history_chunk
*next
;
328 register value_ptr val
;
330 while (value_history_chain
)
332 for (i
= 0; i
< VALUE_HISTORY_CHUNK
; i
++)
333 if ((val
= value_history_chain
->values
[i
]) != NULL
)
335 next
= value_history_chain
->next
;
336 xfree (value_history_chain
);
337 value_history_chain
= next
;
339 value_history_count
= 0;
343 show_values (char *num_exp
, int from_tty
)
346 register value_ptr val
;
351 /* "info history +" should print from the stored position.
352 "info history <exp>" should print around value number <exp>. */
353 if (num_exp
[0] != '+' || num_exp
[1] != '\0')
354 num
= parse_and_eval_long (num_exp
) - 5;
358 /* "info history" means print the last 10 values. */
359 num
= value_history_count
- 9;
365 for (i
= num
; i
< num
+ 10 && i
<= value_history_count
; i
++)
367 val
= access_value_history (i
);
368 printf_filtered ("$%d = ", i
);
369 value_print (val
, gdb_stdout
, 0, Val_pretty_default
);
370 printf_filtered ("\n");
373 /* The next "info history +" should start after what we just printed. */
376 /* Hitting just return after this command should do the same thing as
377 "info history +". If num_exp is null, this is unnecessary, since
378 "info history +" is not useful after "info history". */
379 if (from_tty
&& num_exp
)
386 /* Internal variables. These are variables within the debugger
387 that hold values assigned by debugger commands.
388 The user refers to them with a '$' prefix
389 that does not appear in the variable names stored internally. */
391 static struct internalvar
*internalvars
;
393 /* Look up an internal variable with name NAME. NAME should not
394 normally include a dollar sign.
396 If the specified internal variable does not exist,
397 one is created, with a void value. */
400 lookup_internalvar (char *name
)
402 register struct internalvar
*var
;
404 for (var
= internalvars
; var
; var
= var
->next
)
405 if (STREQ (var
->name
, name
))
408 var
= (struct internalvar
*) xmalloc (sizeof (struct internalvar
));
409 var
->name
= concat (name
, NULL
);
410 var
->value
= allocate_value (builtin_type_void
);
411 release_value (var
->value
);
412 var
->next
= internalvars
;
418 value_of_internalvar (struct internalvar
*var
)
420 register value_ptr val
;
422 #ifdef IS_TRAPPED_INTERNALVAR
423 if (IS_TRAPPED_INTERNALVAR (var
->name
))
424 return VALUE_OF_TRAPPED_INTERNALVAR (var
);
427 val
= value_copy (var
->value
);
428 if (VALUE_LAZY (val
))
429 value_fetch_lazy (val
);
430 VALUE_LVAL (val
) = lval_internalvar
;
431 VALUE_INTERNALVAR (val
) = var
;
436 set_internalvar_component (struct internalvar
*var
, int offset
, int bitpos
,
437 int bitsize
, value_ptr newval
)
439 register char *addr
= VALUE_CONTENTS (var
->value
) + offset
;
441 #ifdef IS_TRAPPED_INTERNALVAR
442 if (IS_TRAPPED_INTERNALVAR (var
->name
))
443 SET_TRAPPED_INTERNALVAR (var
, newval
, bitpos
, bitsize
, offset
);
447 modify_field (addr
, value_as_long (newval
),
450 memcpy (addr
, VALUE_CONTENTS (newval
), TYPE_LENGTH (VALUE_TYPE (newval
)));
454 set_internalvar (struct internalvar
*var
, value_ptr val
)
458 #ifdef IS_TRAPPED_INTERNALVAR
459 if (IS_TRAPPED_INTERNALVAR (var
->name
))
460 SET_TRAPPED_INTERNALVAR (var
, val
, 0, 0, 0);
463 newval
= value_copy (val
);
464 newval
->modifiable
= 1;
466 /* Force the value to be fetched from the target now, to avoid problems
467 later when this internalvar is referenced and the target is gone or
469 if (VALUE_LAZY (newval
))
470 value_fetch_lazy (newval
);
472 /* Begin code which must not call error(). If var->value points to
473 something free'd, an error() obviously leaves a dangling pointer.
474 But we also get a danling pointer if var->value points to
475 something in the value chain (i.e., before release_value is
476 called), because after the error free_all_values will get called before
480 release_value (newval
);
481 /* End code which must not call error(). */
485 internalvar_name (struct internalvar
*var
)
490 /* Free all internalvars. Done when new symtabs are loaded,
491 because that makes the values invalid. */
494 clear_internalvars (void)
496 register struct internalvar
*var
;
501 internalvars
= var
->next
;
509 show_convenience (char *ignore
, int from_tty
)
511 register struct internalvar
*var
;
514 for (var
= internalvars
; var
; var
= var
->next
)
516 #ifdef IS_TRAPPED_INTERNALVAR
517 if (IS_TRAPPED_INTERNALVAR (var
->name
))
524 printf_filtered ("$%s = ", var
->name
);
525 value_print (var
->value
, gdb_stdout
, 0, Val_pretty_default
);
526 printf_filtered ("\n");
529 printf_unfiltered ("No debugger convenience variables now defined.\n\
530 Convenience variables have names starting with \"$\";\n\
531 use \"set\" as in \"set $foo = 5\" to define them.\n");
534 /* Extract a value as a C number (either long or double).
535 Knows how to convert fixed values to double, or
536 floating values to long.
537 Does not deallocate the value. */
540 value_as_long (register value_ptr val
)
542 /* This coerces arrays and functions, which is necessary (e.g.
543 in disassemble_command). It also dereferences references, which
544 I suspect is the most logical thing to do. */
546 return unpack_long (VALUE_TYPE (val
), VALUE_CONTENTS (val
));
550 value_as_double (register value_ptr val
)
555 foo
= unpack_double (VALUE_TYPE (val
), VALUE_CONTENTS (val
), &inv
);
557 error ("Invalid floating value found in program.");
560 /* Extract a value as a C pointer. Does not deallocate the value.
561 Note that val's type may not actually be a pointer; value_as_long
562 handles all the cases. */
564 value_as_address (value_ptr val
)
566 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
567 whether we want this to be true eventually. */
569 /* ADDR_BITS_REMOVE is wrong if we are being called for a
570 non-address (e.g. argument to "signal", "info break", etc.), or
571 for pointers to char, in which the low bits *are* significant. */
572 return ADDR_BITS_REMOVE (value_as_long (val
));
575 /* There are several targets (IA-64, PowerPC, and others) which
576 don't represent pointers to functions as simply the address of
577 the function's entry point. For example, on the IA-64, a
578 function pointer points to a two-word descriptor, generated by
579 the linker, which contains the function's entry point, and the
580 value the IA-64 "global pointer" register should have --- to
581 support position-independent code. The linker generates
582 descriptors only for those functions whose addresses are taken.
584 On such targets, it's difficult for GDB to convert an arbitrary
585 function address into a function pointer; it has to either find
586 an existing descriptor for that function, or call malloc and
587 build its own. On some targets, it is impossible for GDB to
588 build a descriptor at all: the descriptor must contain a jump
589 instruction; data memory cannot be executed; and code memory
592 Upon entry to this function, if VAL is a value of type `function'
593 (that is, TYPE_CODE (VALUE_TYPE (val)) == TYPE_CODE_FUNC), then
594 VALUE_ADDRESS (val) is the address of the function. This is what
595 you'll get if you evaluate an expression like `main'. The call
596 to COERCE_ARRAY below actually does all the usual unary
597 conversions, which includes converting values of type `function'
598 to `pointer to function'. This is the challenging conversion
599 discussed above. Then, `unpack_long' will convert that pointer
600 back into an address.
602 So, suppose the user types `disassemble foo' on an architecture
603 with a strange function pointer representation, on which GDB
604 cannot build its own descriptors, and suppose further that `foo'
605 has no linker-built descriptor. The address->pointer conversion
606 will signal an error and prevent the command from running, even
607 though the next step would have been to convert the pointer
608 directly back into the same address.
610 The following shortcut avoids this whole mess. If VAL is a
611 function, just return its address directly. */
612 if (TYPE_CODE (VALUE_TYPE (val
)) == TYPE_CODE_FUNC
613 || TYPE_CODE (VALUE_TYPE (val
)) == TYPE_CODE_METHOD
)
614 return VALUE_ADDRESS (val
);
618 /* Some architectures (e.g. Harvard), map instruction and data
619 addresses onto a single large unified address space. For
620 instance: An architecture may consider a large integer in the
621 range 0x10000000 .. 0x1000ffff to already represent a data
622 addresses (hence not need a pointer to address conversion) while
623 a small integer would still need to be converted integer to
624 pointer to address. Just assume such architectures handle all
625 integer conversions in a single function. */
629 I think INTEGER_TO_ADDRESS is a good idea as proposed --- but we
630 must admonish GDB hackers to make sure its behavior matches the
631 compiler's, whenever possible.
633 In general, I think GDB should evaluate expressions the same way
634 the compiler does. When the user copies an expression out of
635 their source code and hands it to a `print' command, they should
636 get the same value the compiler would have computed. Any
637 deviation from this rule can cause major confusion and annoyance,
638 and needs to be justified carefully. In other words, GDB doesn't
639 really have the freedom to do these conversions in clever and
642 AndrewC pointed out that users aren't complaining about how GDB
643 casts integers to pointers; they are complaining that they can't
644 take an address from a disassembly listing and give it to `x/i'.
645 This is certainly important.
647 Adding an architecture method like INTEGER_TO_ADDRESS certainly
648 makes it possible for GDB to "get it right" in all circumstances
649 --- the target has complete control over how things get done, so
650 people can Do The Right Thing for their target without breaking
651 anyone else. The standard doesn't specify how integers get
652 converted to pointers; usually, the ABI doesn't either, but
653 ABI-specific code is a more reasonable place to handle it. */
655 if (TYPE_CODE (VALUE_TYPE (val
)) != TYPE_CODE_PTR
656 && TYPE_CODE (VALUE_TYPE (val
)) != TYPE_CODE_REF
657 && INTEGER_TO_ADDRESS_P ())
658 return INTEGER_TO_ADDRESS (VALUE_TYPE (val
), VALUE_CONTENTS (val
));
660 return unpack_long (VALUE_TYPE (val
), VALUE_CONTENTS (val
));
664 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
665 as a long, or as a double, assuming the raw data is described
666 by type TYPE. Knows how to convert different sizes of values
667 and can convert between fixed and floating point. We don't assume
668 any alignment for the raw data. Return value is in host byte order.
670 If you want functions and arrays to be coerced to pointers, and
671 references to be dereferenced, call value_as_long() instead.
673 C++: It is assumed that the front-end has taken care of
674 all matters concerning pointers to members. A pointer
675 to member which reaches here is considered to be equivalent
676 to an INT (or some size). After all, it is only an offset. */
679 unpack_long (struct type
*type
, char *valaddr
)
681 register enum type_code code
= TYPE_CODE (type
);
682 register int len
= TYPE_LENGTH (type
);
683 register int nosign
= TYPE_UNSIGNED (type
);
685 if (current_language
->la_language
== language_scm
686 && is_scmvalue_type (type
))
687 return scm_unpack (type
, valaddr
, TYPE_CODE_INT
);
691 case TYPE_CODE_TYPEDEF
:
692 return unpack_long (check_typedef (type
), valaddr
);
697 case TYPE_CODE_RANGE
:
699 return extract_unsigned_integer (valaddr
, len
);
701 return extract_signed_integer (valaddr
, len
);
704 return extract_typed_floating (valaddr
, type
);
708 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
709 whether we want this to be true eventually. */
710 return extract_typed_address (valaddr
, type
);
712 case TYPE_CODE_MEMBER
:
713 error ("not implemented: member types in unpack_long");
716 error ("Value can't be converted to integer.");
718 return 0; /* Placate lint. */
721 /* Return a double value from the specified type and address.
722 INVP points to an int which is set to 0 for valid value,
723 1 for invalid value (bad float format). In either case,
724 the returned double is OK to use. Argument is in target
725 format, result is in host format. */
728 unpack_double (struct type
*type
, char *valaddr
, int *invp
)
734 *invp
= 0; /* Assume valid. */
735 CHECK_TYPEDEF (type
);
736 code
= TYPE_CODE (type
);
737 len
= TYPE_LENGTH (type
);
738 nosign
= TYPE_UNSIGNED (type
);
739 if (code
== TYPE_CODE_FLT
)
742 if (INVALID_FLOAT (valaddr
, len
))
745 return 1.234567891011121314;
748 return extract_typed_floating (valaddr
, type
);
752 /* Unsigned -- be sure we compensate for signed LONGEST. */
753 return (ULONGEST
) unpack_long (type
, valaddr
);
757 /* Signed -- we are OK with unpack_long. */
758 return unpack_long (type
, valaddr
);
762 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
763 as a CORE_ADDR, assuming the raw data is described by type TYPE.
764 We don't assume any alignment for the raw data. Return value is in
767 If you want functions and arrays to be coerced to pointers, and
768 references to be dereferenced, call value_as_address() instead.
770 C++: It is assumed that the front-end has taken care of
771 all matters concerning pointers to members. A pointer
772 to member which reaches here is considered to be equivalent
773 to an INT (or some size). After all, it is only an offset. */
776 unpack_pointer (struct type
*type
, char *valaddr
)
778 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
779 whether we want this to be true eventually. */
780 return unpack_long (type
, valaddr
);
784 /* Get the value of the FIELDN'th field (which must be static) of TYPE. */
787 value_static_field (struct type
*type
, int fieldno
)
791 if (TYPE_FIELD_STATIC_HAS_ADDR (type
, fieldno
))
793 addr
= TYPE_FIELD_STATIC_PHYSADDR (type
, fieldno
);
798 char *phys_name
= TYPE_FIELD_STATIC_PHYSNAME (type
, fieldno
);
799 struct symbol
*sym
= lookup_symbol (phys_name
, 0, VAR_NAMESPACE
, 0, NULL
);
802 /* With some compilers, e.g. HP aCC, static data members are reported
803 as non-debuggable symbols */
804 struct minimal_symbol
*msym
= lookup_minimal_symbol (phys_name
, NULL
, NULL
);
809 addr
= SYMBOL_VALUE_ADDRESS (msym
);
810 sect
= SYMBOL_BFD_SECTION (msym
);
815 /* Anything static that isn't a constant, has an address */
816 if (SYMBOL_CLASS (sym
) != LOC_CONST
)
818 addr
= SYMBOL_VALUE_ADDRESS (sym
);
819 sect
= SYMBOL_BFD_SECTION (sym
);
821 /* However, static const's do not, the value is already known. */
824 return value_from_longest (TYPE_FIELD_TYPE (type
, fieldno
), SYMBOL_VALUE (sym
));
827 SET_FIELD_PHYSADDR (TYPE_FIELD (type
, fieldno
), addr
);
829 return value_at (TYPE_FIELD_TYPE (type
, fieldno
), addr
, sect
);
832 /* Change the enclosing type of a value object VAL to NEW_ENCL_TYPE.
833 You have to be careful here, since the size of the data area for the value
834 is set by the length of the enclosing type. So if NEW_ENCL_TYPE is bigger
835 than the old enclosing type, you have to allocate more space for the data.
836 The return value is a pointer to the new version of this value structure. */
839 value_change_enclosing_type (value_ptr val
, struct type
*new_encl_type
)
841 if (TYPE_LENGTH (new_encl_type
) <= TYPE_LENGTH (VALUE_ENCLOSING_TYPE (val
)))
843 VALUE_ENCLOSING_TYPE (val
) = new_encl_type
;
849 register value_ptr prev
;
851 new_val
= (value_ptr
) xrealloc (val
, sizeof (struct value
) + TYPE_LENGTH (new_encl_type
));
853 /* We have to make sure this ends up in the same place in the value
854 chain as the original copy, so it's clean-up behavior is the same.
855 If the value has been released, this is a waste of time, but there
856 is no way to tell that in advance, so... */
858 if (val
!= all_values
)
860 for (prev
= all_values
; prev
!= NULL
; prev
= prev
->next
)
862 if (prev
->next
== val
)
864 prev
->next
= new_val
;
874 /* Given a value ARG1 (offset by OFFSET bytes)
875 of a struct or union type ARG_TYPE,
876 extract and return the value of one of its (non-static) fields.
877 FIELDNO says which field. */
880 value_primitive_field (register value_ptr arg1
, int offset
,
881 register int fieldno
, register struct type
*arg_type
)
883 register value_ptr v
;
884 register struct type
*type
;
886 CHECK_TYPEDEF (arg_type
);
887 type
= TYPE_FIELD_TYPE (arg_type
, fieldno
);
889 /* Handle packed fields */
891 if (TYPE_FIELD_BITSIZE (arg_type
, fieldno
))
893 v
= value_from_longest (type
,
894 unpack_field_as_long (arg_type
,
895 VALUE_CONTENTS (arg1
)
898 VALUE_BITPOS (v
) = TYPE_FIELD_BITPOS (arg_type
, fieldno
) % 8;
899 VALUE_BITSIZE (v
) = TYPE_FIELD_BITSIZE (arg_type
, fieldno
);
900 VALUE_OFFSET (v
) = VALUE_OFFSET (arg1
) + offset
901 + TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
903 else if (fieldno
< TYPE_N_BASECLASSES (arg_type
))
905 /* This field is actually a base subobject, so preserve the
906 entire object's contents for later references to virtual
908 v
= allocate_value (VALUE_ENCLOSING_TYPE (arg1
));
909 VALUE_TYPE (v
) = type
;
910 if (VALUE_LAZY (arg1
))
913 memcpy (VALUE_CONTENTS_ALL_RAW (v
), VALUE_CONTENTS_ALL_RAW (arg1
),
914 TYPE_LENGTH (VALUE_ENCLOSING_TYPE (arg1
)));
915 VALUE_OFFSET (v
) = VALUE_OFFSET (arg1
);
916 VALUE_EMBEDDED_OFFSET (v
)
918 VALUE_EMBEDDED_OFFSET (arg1
) +
919 TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
923 /* Plain old data member */
924 offset
+= TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
925 v
= allocate_value (type
);
926 if (VALUE_LAZY (arg1
))
929 memcpy (VALUE_CONTENTS_RAW (v
),
930 VALUE_CONTENTS_RAW (arg1
) + offset
,
932 VALUE_OFFSET (v
) = VALUE_OFFSET (arg1
) + offset
933 + VALUE_EMBEDDED_OFFSET (arg1
);
935 VALUE_LVAL (v
) = VALUE_LVAL (arg1
);
936 if (VALUE_LVAL (arg1
) == lval_internalvar
)
937 VALUE_LVAL (v
) = lval_internalvar_component
;
938 VALUE_ADDRESS (v
) = VALUE_ADDRESS (arg1
);
939 VALUE_REGNO (v
) = VALUE_REGNO (arg1
);
940 /* VALUE_OFFSET (v) = VALUE_OFFSET (arg1) + offset
941 + TYPE_FIELD_BITPOS (arg_type, fieldno) / 8; */
945 /* Given a value ARG1 of a struct or union type,
946 extract and return the value of one of its (non-static) fields.
947 FIELDNO says which field. */
950 value_field (register value_ptr arg1
, register int fieldno
)
952 return value_primitive_field (arg1
, 0, fieldno
, VALUE_TYPE (arg1
));
955 /* Return a non-virtual function as a value.
956 F is the list of member functions which contains the desired method.
957 J is an index into F which provides the desired method. */
960 value_fn_field (value_ptr
*arg1p
, struct fn_field
*f
, int j
, struct type
*type
,
963 register value_ptr v
;
964 register struct type
*ftype
= TYPE_FN_FIELD_TYPE (f
, j
);
967 sym
= lookup_symbol (TYPE_FN_FIELD_PHYSNAME (f
, j
),
968 0, VAR_NAMESPACE
, 0, NULL
);
972 error ("Internal error: could not find physical method named %s",
973 TYPE_FN_FIELD_PHYSNAME (f, j));
976 v
= allocate_value (ftype
);
977 VALUE_ADDRESS (v
) = BLOCK_START (SYMBOL_BLOCK_VALUE (sym
));
978 VALUE_TYPE (v
) = ftype
;
982 if (type
!= VALUE_TYPE (*arg1p
))
983 *arg1p
= value_ind (value_cast (lookup_pointer_type (type
),
984 value_addr (*arg1p
)));
986 /* Move the `this' pointer according to the offset.
987 VALUE_OFFSET (*arg1p) += offset;
994 /* ARG is a pointer to an object we know to be at least
995 a DTYPE. BTYPE is the most derived basetype that has
996 already been searched (and need not be searched again).
997 After looking at the vtables between BTYPE and DTYPE,
998 return the most derived type we find. The caller must
999 be satisfied when the return value == DTYPE.
1001 FIXME-tiemann: should work with dossier entries as well.
1002 NOTICE - djb: I see no good reason at all to keep this function now that
1003 we have RTTI support. It's used in literally one place, and it's
1004 hard to keep this function up to date when it's purpose is served
1005 by value_rtti_type efficiently.
1006 Consider it gone for 5.1. */
1009 value_headof (value_ptr in_arg
, struct type
*btype
, struct type
*dtype
)
1011 /* First collect the vtables we must look at for this object. */
1012 value_ptr arg
, vtbl
;
1014 char *demangled_name
;
1015 struct minimal_symbol
*msymbol
;
1017 btype
= TYPE_VPTR_BASETYPE (dtype
);
1018 CHECK_TYPEDEF (btype
);
1021 arg
= value_cast (lookup_pointer_type (btype
), arg
);
1022 if (TYPE_CODE (VALUE_TYPE (arg
)) == TYPE_CODE_REF
)
1025 * Copy the value, but change the type from (T&) to (T*).
1026 * We keep the same location information, which is efficient,
1027 * and allows &(&X) to get the location containing the reference.
1029 arg
= value_copy (arg
);
1030 VALUE_TYPE (arg
) = lookup_pointer_type (TYPE_TARGET_TYPE (VALUE_TYPE (arg
)));
1032 if (VALUE_ADDRESS(value_field (value_ind(arg
), TYPE_VPTR_FIELDNO (btype
)))==0)
1035 vtbl
= value_ind (value_field (value_ind (arg
), TYPE_VPTR_FIELDNO (btype
)));
1036 /* Turn vtable into typeinfo function */
1037 VALUE_OFFSET(vtbl
)+=4;
1039 msymbol
= lookup_minimal_symbol_by_pc ( value_as_address(value_ind(vtbl
)) );
1041 || (demangled_name
= SYMBOL_NAME (msymbol
)) == NULL
)
1043 /* If we expected to find a vtable, but did not, let the user
1044 know that we aren't happy, but don't throw an error.
1045 FIXME: there has to be a better way to do this. */
1046 struct type
*error_type
= (struct type
*) xmalloc (sizeof (struct type
));
1047 memcpy (error_type
, VALUE_TYPE (in_arg
), sizeof (struct type
));
1048 TYPE_NAME (error_type
) = savestring ("suspicious *", sizeof ("suspicious *"));
1049 VALUE_TYPE (in_arg
) = error_type
;
1052 demangled_name
= cplus_demangle(demangled_name
,DMGL_ANSI
);
1053 *(strchr (demangled_name
, ' ')) = '\0';
1055 sym
= lookup_symbol (demangled_name
, 0, VAR_NAMESPACE
, 0, 0);
1057 error ("could not find type declaration for `%s'", demangled_name
);
1060 VALUE_TYPE (arg
) = lookup_pointer_type (SYMBOL_TYPE (sym
));
1064 /* ARG is a pointer object of type TYPE. If TYPE has virtual
1065 function tables, probe ARG's tables (including the vtables
1066 of its baseclasses) to figure out the most derived type that ARG
1067 could actually be a pointer to. */
1070 value_from_vtable_info (value_ptr arg
, struct type
*type
)
1072 /* Take care of preliminaries. */
1073 if (TYPE_VPTR_FIELDNO (type
) < 0)
1074 fill_in_vptr_fieldno (type
);
1075 if (TYPE_VPTR_FIELDNO (type
) < 0)
1078 return value_headof (arg
, 0, type
);
1081 /* Return true if the INDEXth field of TYPE is a virtual baseclass
1082 pointer which is for the base class whose type is BASECLASS. */
1085 vb_match (struct type
*type
, int index
, struct type
*basetype
)
1087 struct type
*fieldtype
;
1088 char *name
= TYPE_FIELD_NAME (type
, index
);
1089 char *field_class_name
= NULL
;
1093 /* gcc 2.4 uses _vb$. */
1094 if (name
[1] == 'v' && name
[2] == 'b' && is_cplus_marker (name
[3]))
1095 field_class_name
= name
+ 4;
1096 /* gcc 2.5 will use __vb_. */
1097 if (name
[1] == '_' && name
[2] == 'v' && name
[3] == 'b' && name
[4] == '_')
1098 field_class_name
= name
+ 5;
1100 if (field_class_name
== NULL
)
1101 /* This field is not a virtual base class pointer. */
1104 /* It's a virtual baseclass pointer, now we just need to find out whether
1105 it is for this baseclass. */
1106 fieldtype
= TYPE_FIELD_TYPE (type
, index
);
1107 if (fieldtype
== NULL
1108 || TYPE_CODE (fieldtype
) != TYPE_CODE_PTR
)
1109 /* "Can't happen". */
1112 /* What we check for is that either the types are equal (needed for
1113 nameless types) or have the same name. This is ugly, and a more
1114 elegant solution should be devised (which would probably just push
1115 the ugliness into symbol reading unless we change the stabs format). */
1116 if (TYPE_TARGET_TYPE (fieldtype
) == basetype
)
1119 if (TYPE_NAME (basetype
) != NULL
1120 && TYPE_NAME (TYPE_TARGET_TYPE (fieldtype
)) != NULL
1121 && STREQ (TYPE_NAME (basetype
),
1122 TYPE_NAME (TYPE_TARGET_TYPE (fieldtype
))))
1127 /* Compute the offset of the baseclass which is
1128 the INDEXth baseclass of class TYPE,
1129 for value at VALADDR (in host) at ADDRESS (in target).
1130 The result is the offset of the baseclass value relative
1131 to (the address of)(ARG) + OFFSET.
1133 -1 is returned on error. */
1136 baseclass_offset (struct type
*type
, int index
, char *valaddr
,
1139 struct type
*basetype
= TYPE_BASECLASS (type
, index
);
1141 if (BASETYPE_VIA_VIRTUAL (type
, index
))
1143 /* Must hunt for the pointer to this virtual baseclass. */
1144 register int i
, len
= TYPE_NFIELDS (type
);
1145 register int n_baseclasses
= TYPE_N_BASECLASSES (type
);
1147 /* First look for the virtual baseclass pointer
1149 for (i
= n_baseclasses
; i
< len
; i
++)
1151 if (vb_match (type
, i
, basetype
))
1154 = unpack_pointer (TYPE_FIELD_TYPE (type
, i
),
1155 valaddr
+ (TYPE_FIELD_BITPOS (type
, i
) / 8));
1157 return addr
- (LONGEST
) address
;
1160 /* Not in the fields, so try looking through the baseclasses. */
1161 for (i
= index
+ 1; i
< n_baseclasses
; i
++)
1164 baseclass_offset (type
, i
, valaddr
, address
);
1172 /* Baseclass is easily computed. */
1173 return TYPE_BASECLASS_BITPOS (type
, index
) / 8;
1176 /* Unpack a field FIELDNO of the specified TYPE, from the anonymous object at
1179 Extracting bits depends on endianness of the machine. Compute the
1180 number of least significant bits to discard. For big endian machines,
1181 we compute the total number of bits in the anonymous object, subtract
1182 off the bit count from the MSB of the object to the MSB of the
1183 bitfield, then the size of the bitfield, which leaves the LSB discard
1184 count. For little endian machines, the discard count is simply the
1185 number of bits from the LSB of the anonymous object to the LSB of the
1188 If the field is signed, we also do sign extension. */
1191 unpack_field_as_long (struct type
*type
, char *valaddr
, int fieldno
)
1195 int bitpos
= TYPE_FIELD_BITPOS (type
, fieldno
);
1196 int bitsize
= TYPE_FIELD_BITSIZE (type
, fieldno
);
1198 struct type
*field_type
;
1200 val
= extract_unsigned_integer (valaddr
+ bitpos
/ 8, sizeof (val
));
1201 field_type
= TYPE_FIELD_TYPE (type
, fieldno
);
1202 CHECK_TYPEDEF (field_type
);
1204 /* Extract bits. See comment above. */
1206 if (BITS_BIG_ENDIAN
)
1207 lsbcount
= (sizeof val
* 8 - bitpos
% 8 - bitsize
);
1209 lsbcount
= (bitpos
% 8);
1212 /* If the field does not entirely fill a LONGEST, then zero the sign bits.
1213 If the field is signed, and is negative, then sign extend. */
1215 if ((bitsize
> 0) && (bitsize
< 8 * (int) sizeof (val
)))
1217 valmask
= (((ULONGEST
) 1) << bitsize
) - 1;
1219 if (!TYPE_UNSIGNED (field_type
))
1221 if (val
& (valmask
^ (valmask
>> 1)))
1230 /* Modify the value of a bitfield. ADDR points to a block of memory in
1231 target byte order; the bitfield starts in the byte pointed to. FIELDVAL
1232 is the desired value of the field, in host byte order. BITPOS and BITSIZE
1233 indicate which bits (in target bit order) comprise the bitfield. */
1236 modify_field (char *addr
, LONGEST fieldval
, int bitpos
, int bitsize
)
1240 /* If a negative fieldval fits in the field in question, chop
1241 off the sign extension bits. */
1242 if (bitsize
< (8 * (int) sizeof (fieldval
))
1243 && (~fieldval
& ~((1 << (bitsize
- 1)) - 1)) == 0)
1244 fieldval
= fieldval
& ((1 << bitsize
) - 1);
1246 /* Warn if value is too big to fit in the field in question. */
1247 if (bitsize
< (8 * (int) sizeof (fieldval
))
1248 && 0 != (fieldval
& ~((1 << bitsize
) - 1)))
1250 /* FIXME: would like to include fieldval in the message, but
1251 we don't have a sprintf_longest. */
1252 warning ("Value does not fit in %d bits.", bitsize
);
1254 /* Truncate it, otherwise adjoining fields may be corrupted. */
1255 fieldval
= fieldval
& ((1 << bitsize
) - 1);
1258 oword
= extract_signed_integer (addr
, sizeof oword
);
1260 /* Shifting for bit field depends on endianness of the target machine. */
1261 if (BITS_BIG_ENDIAN
)
1262 bitpos
= sizeof (oword
) * 8 - bitpos
- bitsize
;
1264 /* Mask out old value, while avoiding shifts >= size of oword */
1265 if (bitsize
< 8 * (int) sizeof (oword
))
1266 oword
&= ~(((((ULONGEST
) 1) << bitsize
) - 1) << bitpos
);
1268 oword
&= ~((~(ULONGEST
) 0) << bitpos
);
1269 oword
|= fieldval
<< bitpos
;
1271 store_signed_integer (addr
, sizeof oword
, oword
);
1274 /* Convert C numbers into newly allocated values */
1277 value_from_longest (struct type
*type
, register LONGEST num
)
1279 register value_ptr val
= allocate_value (type
);
1280 register enum type_code code
;
1283 code
= TYPE_CODE (type
);
1284 len
= TYPE_LENGTH (type
);
1288 case TYPE_CODE_TYPEDEF
:
1289 type
= check_typedef (type
);
1292 case TYPE_CODE_CHAR
:
1293 case TYPE_CODE_ENUM
:
1294 case TYPE_CODE_BOOL
:
1295 case TYPE_CODE_RANGE
:
1296 store_signed_integer (VALUE_CONTENTS_RAW (val
), len
, num
);
1301 store_typed_address (VALUE_CONTENTS_RAW (val
), type
, (CORE_ADDR
) num
);
1305 error ("Unexpected type (%d) encountered for integer constant.", code
);
1311 /* Create a value representing a pointer of type TYPE to the address
1314 value_from_pointer (struct type
*type
, CORE_ADDR addr
)
1316 value_ptr val
= allocate_value (type
);
1317 store_typed_address (VALUE_CONTENTS_RAW (val
), type
, addr
);
1322 /* Create a value for a string constant to be stored locally
1323 (not in the inferior's memory space, but in GDB memory).
1324 This is analogous to value_from_longest, which also does not
1325 use inferior memory. String shall NOT contain embedded nulls. */
1328 value_from_string (char *ptr
)
1331 int len
= strlen (ptr
);
1332 int lowbound
= current_language
->string_lower_bound
;
1333 struct type
*rangetype
=
1334 create_range_type ((struct type
*) NULL
,
1336 lowbound
, len
+ lowbound
- 1);
1337 struct type
*stringtype
=
1338 create_array_type ((struct type
*) NULL
,
1339 *current_language
->string_char_type
,
1342 val
= allocate_value (stringtype
);
1343 memcpy (VALUE_CONTENTS_RAW (val
), ptr
, len
);
1348 value_from_double (struct type
*type
, DOUBLEST num
)
1350 register value_ptr val
= allocate_value (type
);
1351 struct type
*base_type
= check_typedef (type
);
1352 register enum type_code code
= TYPE_CODE (base_type
);
1353 register int len
= TYPE_LENGTH (base_type
);
1355 if (code
== TYPE_CODE_FLT
)
1357 store_typed_floating (VALUE_CONTENTS_RAW (val
), base_type
, num
);
1360 error ("Unexpected type encountered for floating constant.");
1365 /* Deal with the value that is "about to be returned". */
1367 /* Return the value that a function returning now
1368 would be returning to its caller, assuming its type is VALTYPE.
1369 RETBUF is where we look for what ought to be the contents
1370 of the registers (in raw form). This is because it is often
1371 desirable to restore old values to those registers
1372 after saving the contents of interest, and then call
1373 this function using the saved values.
1374 struct_return is non-zero when the function in question is
1375 using the structure return conventions on the machine in question;
1376 0 when it is using the value returning conventions (this often
1377 means returning pointer to where structure is vs. returning value). */
1381 value_being_returned (struct type
*valtype
, char *retbuf
, int struct_return
)
1383 register value_ptr val
;
1386 /* If this is not defined, just use EXTRACT_RETURN_VALUE instead. */
1387 if (EXTRACT_STRUCT_VALUE_ADDRESS_P ())
1390 addr
= EXTRACT_STRUCT_VALUE_ADDRESS (retbuf
);
1392 error ("Function return value unknown.");
1393 return value_at (valtype
, addr
, NULL
);
1396 val
= allocate_value (valtype
);
1397 CHECK_TYPEDEF (valtype
);
1398 EXTRACT_RETURN_VALUE (valtype
, retbuf
, VALUE_CONTENTS_RAW (val
));
1403 /* Should we use EXTRACT_STRUCT_VALUE_ADDRESS instead of
1404 EXTRACT_RETURN_VALUE? GCC_P is true if compiled with gcc
1405 and TYPE is the type (which is known to be struct, union or array).
1407 On most machines, the struct convention is used unless we are
1408 using gcc and the type is of a special size. */
1409 /* As of about 31 Mar 93, GCC was changed to be compatible with the
1410 native compiler. GCC 2.3.3 was the last release that did it the
1411 old way. Since gcc2_compiled was not changed, we have no
1412 way to correctly win in all cases, so we just do the right thing
1413 for gcc1 and for gcc2 after this change. Thus it loses for gcc
1414 2.0-2.3.3. This is somewhat unfortunate, but changing gcc2_compiled
1415 would cause more chaos than dealing with some struct returns being
1419 generic_use_struct_convention (int gcc_p
, struct type
*value_type
)
1421 return !((gcc_p
== 1)
1422 && (TYPE_LENGTH (value_type
) == 1
1423 || TYPE_LENGTH (value_type
) == 2
1424 || TYPE_LENGTH (value_type
) == 4
1425 || TYPE_LENGTH (value_type
) == 8));
1428 /* Return true if the function specified is using the structure returning
1429 convention on this machine to return arguments, or 0 if it is using
1430 the value returning convention. FUNCTION is the value representing
1431 the function, FUNCADDR is the address of the function, and VALUE_TYPE
1432 is the type returned by the function. GCC_P is nonzero if compiled
1437 using_struct_return (value_ptr function
, CORE_ADDR funcaddr
,
1438 struct type
*value_type
, int gcc_p
)
1440 register enum type_code code
= TYPE_CODE (value_type
);
1442 if (code
== TYPE_CODE_ERROR
)
1443 error ("Function return type unknown.");
1445 if (code
== TYPE_CODE_STRUCT
1446 || code
== TYPE_CODE_UNION
1447 || code
== TYPE_CODE_ARRAY
1448 || RETURN_VALUE_ON_STACK (value_type
))
1449 return USE_STRUCT_CONVENTION (gcc_p
, value_type
);
1454 /* Store VAL so it will be returned if a function returns now.
1455 Does not verify that VAL's type matches what the current
1456 function wants to return. */
1459 set_return_value (value_ptr val
)
1461 struct type
*type
= check_typedef (VALUE_TYPE (val
));
1462 register enum type_code code
= TYPE_CODE (type
);
1464 if (code
== TYPE_CODE_ERROR
)
1465 error ("Function return type unknown.");
1467 if (code
== TYPE_CODE_STRUCT
1468 || code
== TYPE_CODE_UNION
) /* FIXME, implement struct return. */
1469 error ("GDB does not support specifying a struct or union return value.");
1471 STORE_RETURN_VALUE (type
, VALUE_CONTENTS (val
));
1475 _initialize_values (void)
1477 add_cmd ("convenience", no_class
, show_convenience
,
1478 "Debugger convenience (\"$foo\") variables.\n\
1479 These variables are created when you assign them values;\n\
1480 thus, \"print $foo=1\" gives \"$foo\" the value 1. Values may be any type.\n\n\
1481 A few convenience variables are given values automatically:\n\
1482 \"$_\"holds the last address examined with \"x\" or \"info lines\",\n\
1483 \"$__\" holds the contents of the last address examined with \"x\".",
1486 add_cmd ("values", no_class
, show_values
,
1487 "Elements of value history around item number IDX (or last ten).",