1 /* Low level packing and unpacking of values for GDB, the GNU Debugger.
2 Copyright 1986, 1987, 1989, 1991 Free Software Foundation, Inc.
4 This file is part of GDB.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
32 /* Local function prototypes. */
34 static value_ptr value_headof
PARAMS ((value_ptr
, struct type
*,
37 static void show_values
PARAMS ((char *, int));
39 static void show_convenience
PARAMS ((char *, int));
41 /* The value-history records all the values printed
42 by print commands during this session. Each chunk
43 records 60 consecutive values. The first chunk on
44 the chain records the most recent values.
45 The total number of values is in value_history_count. */
47 #define VALUE_HISTORY_CHUNK 60
49 struct value_history_chunk
51 struct value_history_chunk
*next
;
52 value_ptr values
[VALUE_HISTORY_CHUNK
];
55 /* Chain of chunks now in use. */
57 static struct value_history_chunk
*value_history_chain
;
59 static int value_history_count
; /* Abs number of last entry stored */
61 /* List of all value objects currently allocated
62 (except for those released by calls to release_value)
63 This is so they can be freed after each command. */
65 static value_ptr all_values
;
67 /* Allocate a value that has the correct length for type TYPE. */
73 register value_ptr val
;
75 check_stub_type (type
);
77 val
= (struct value
*) xmalloc (sizeof (struct value
) + TYPE_LENGTH (type
));
78 VALUE_NEXT (val
) = all_values
;
80 VALUE_TYPE (val
) = type
;
81 VALUE_LVAL (val
) = not_lval
;
82 VALUE_ADDRESS (val
) = 0;
83 VALUE_FRAME (val
) = 0;
84 VALUE_OFFSET (val
) = 0;
85 VALUE_BITPOS (val
) = 0;
86 VALUE_BITSIZE (val
) = 0;
87 VALUE_REPEATED (val
) = 0;
88 VALUE_REPETITIONS (val
) = 0;
89 VALUE_REGNO (val
) = -1;
91 VALUE_OPTIMIZED_OUT (val
) = 0;
96 /* Allocate a value that has the correct length
97 for COUNT repetitions type TYPE. */
100 allocate_repeat_value (type
, count
)
104 register value_ptr val
;
107 (value_ptr
) xmalloc (sizeof (struct value
) + TYPE_LENGTH (type
) * count
);
108 VALUE_NEXT (val
) = all_values
;
110 VALUE_TYPE (val
) = type
;
111 VALUE_LVAL (val
) = not_lval
;
112 VALUE_ADDRESS (val
) = 0;
113 VALUE_FRAME (val
) = 0;
114 VALUE_OFFSET (val
) = 0;
115 VALUE_BITPOS (val
) = 0;
116 VALUE_BITSIZE (val
) = 0;
117 VALUE_REPEATED (val
) = 1;
118 VALUE_REPETITIONS (val
) = count
;
119 VALUE_REGNO (val
) = -1;
120 VALUE_LAZY (val
) = 0;
121 VALUE_OPTIMIZED_OUT (val
) = 0;
125 /* Return a mark in the value chain. All values allocated after the
126 mark is obtained (except for those released) are subject to being freed
127 if a subsequent value_free_to_mark is passed the mark. */
134 /* Free all values allocated since MARK was obtained by value_mark
135 (except for those released). */
137 value_free_to_mark (mark
)
142 for (val
= all_values
; val
&& val
!= mark
; val
= next
)
144 next
= VALUE_NEXT (val
);
150 /* Free all the values that have been allocated (except for those released).
151 Called after each command, successful or not. */
156 register value_ptr val
, next
;
158 for (val
= all_values
; val
; val
= next
)
160 next
= VALUE_NEXT (val
);
167 /* Remove VAL from the chain all_values
168 so it will not be freed automatically. */
172 register value_ptr val
;
174 register value_ptr v
;
176 if (all_values
== val
)
178 all_values
= val
->next
;
182 for (v
= all_values
; v
; v
= v
->next
)
192 /* Return a copy of the value ARG.
193 It contains the same contents, for same memory address,
194 but it's a different block of storage. */
200 register value_ptr val
;
201 register struct type
*type
= VALUE_TYPE (arg
);
202 if (VALUE_REPEATED (arg
))
203 val
= allocate_repeat_value (type
, VALUE_REPETITIONS (arg
));
205 val
= allocate_value (type
);
206 VALUE_LVAL (val
) = VALUE_LVAL (arg
);
207 VALUE_ADDRESS (val
) = VALUE_ADDRESS (arg
);
208 VALUE_OFFSET (val
) = VALUE_OFFSET (arg
);
209 VALUE_BITPOS (val
) = VALUE_BITPOS (arg
);
210 VALUE_BITSIZE (val
) = VALUE_BITSIZE (arg
);
211 VALUE_REGNO (val
) = VALUE_REGNO (arg
);
212 VALUE_LAZY (val
) = VALUE_LAZY (arg
);
213 val
->modifiable
= arg
->modifiable
;
214 if (!VALUE_LAZY (val
))
216 memcpy (VALUE_CONTENTS_RAW (val
), VALUE_CONTENTS_RAW (arg
),
217 TYPE_LENGTH (VALUE_TYPE (arg
))
218 * (VALUE_REPEATED (arg
) ? VALUE_REPETITIONS (arg
) : 1));
223 /* Access to the value history. */
225 /* Record a new value in the value history.
226 Returns the absolute history index of the entry.
227 Result of -1 indicates the value was not saved; otherwise it is the
228 value history index of this new item. */
231 record_latest_value (val
)
236 /* Check error now if about to store an invalid float. We return -1
237 to the caller, but allow them to continue, e.g. to print it as "Nan". */
238 if (TYPE_CODE (VALUE_TYPE (val
)) == TYPE_CODE_FLT
)
240 unpack_double (VALUE_TYPE (val
), VALUE_CONTENTS (val
), &i
);
241 if (i
) return -1; /* Indicate value not saved in history */
244 /* Here we treat value_history_count as origin-zero
245 and applying to the value being stored now. */
247 i
= value_history_count
% VALUE_HISTORY_CHUNK
;
250 register struct value_history_chunk
*new
251 = (struct value_history_chunk
*)
252 xmalloc (sizeof (struct value_history_chunk
));
253 memset (new->values
, 0, sizeof new->values
);
254 new->next
= value_history_chain
;
255 value_history_chain
= new;
258 value_history_chain
->values
[i
] = val
;
260 /* We don't want this value to have anything to do with the inferior anymore.
261 In particular, "set $1 = 50" should not affect the variable from which
262 the value was taken, and fast watchpoints should be able to assume that
263 a value on the value history never changes. */
264 if (VALUE_LAZY (val
))
265 value_fetch_lazy (val
);
266 /* We preserve VALUE_LVAL so that the user can find out where it was fetched
267 from. This is a bit dubious, because then *&$1 does not just return $1
268 but the current contents of that location. c'est la vie... */
272 /* Now we regard value_history_count as origin-one
273 and applying to the value just stored. */
275 return ++value_history_count
;
278 /* Return a copy of the value in the history with sequence number NUM. */
281 access_value_history (num
)
284 register struct value_history_chunk
*chunk
;
286 register int absnum
= num
;
289 absnum
+= value_history_count
;
294 error ("The history is empty.");
296 error ("There is only one value in the history.");
298 error ("History does not go back to $$%d.", -num
);
300 if (absnum
> value_history_count
)
301 error ("History has not yet reached $%d.", absnum
);
305 /* Now absnum is always absolute and origin zero. */
307 chunk
= value_history_chain
;
308 for (i
= (value_history_count
- 1) / VALUE_HISTORY_CHUNK
- absnum
/ VALUE_HISTORY_CHUNK
;
312 return value_copy (chunk
->values
[absnum
% VALUE_HISTORY_CHUNK
]);
315 /* Clear the value history entirely.
316 Must be done when new symbol tables are loaded,
317 because the type pointers become invalid. */
320 clear_value_history ()
322 register struct value_history_chunk
*next
;
324 register value_ptr val
;
326 while (value_history_chain
)
328 for (i
= 0; i
< VALUE_HISTORY_CHUNK
; i
++)
329 if ((val
= value_history_chain
->values
[i
]) != NULL
)
331 next
= value_history_chain
->next
;
332 free ((PTR
)value_history_chain
);
333 value_history_chain
= next
;
335 value_history_count
= 0;
339 show_values (num_exp
, from_tty
)
344 register value_ptr val
;
349 /* "info history +" should print from the stored position.
350 "info history <exp>" should print around value number <exp>. */
351 if (num_exp
[0] != '+' || num_exp
[1] != '\0')
352 num
= parse_and_eval_address (num_exp
) - 5;
356 /* "info history" means print the last 10 values. */
357 num
= value_history_count
- 9;
363 for (i
= num
; i
< num
+ 10 && i
<= value_history_count
; i
++)
365 val
= access_value_history (i
);
366 printf_filtered ("$%d = ", i
);
367 value_print (val
, gdb_stdout
, 0, Val_pretty_default
);
368 printf_filtered ("\n");
371 /* The next "info history +" should start after what we just printed. */
374 /* Hitting just return after this command should do the same thing as
375 "info history +". If num_exp is null, this is unnecessary, since
376 "info history +" is not useful after "info history". */
377 if (from_tty
&& num_exp
)
384 /* Internal variables. These are variables within the debugger
385 that hold values assigned by debugger commands.
386 The user refers to them with a '$' prefix
387 that does not appear in the variable names stored internally. */
389 static struct internalvar
*internalvars
;
391 /* Look up an internal variable with name NAME. NAME should not
392 normally include a dollar sign.
394 If the specified internal variable does not exist,
395 one is created, with a void value. */
398 lookup_internalvar (name
)
401 register struct internalvar
*var
;
403 for (var
= internalvars
; var
; var
= var
->next
)
404 if (STREQ (var
->name
, name
))
407 var
= (struct internalvar
*) xmalloc (sizeof (struct internalvar
));
408 var
->name
= concat (name
, NULL
);
409 var
->value
= allocate_value (builtin_type_void
);
410 release_value (var
->value
);
411 var
->next
= internalvars
;
417 value_of_internalvar (var
)
418 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 (var
, offset
, bitpos
, bitsize
, newval
)
437 struct internalvar
*var
;
438 int offset
, bitpos
, bitsize
;
441 register char *addr
= VALUE_CONTENTS (var
->value
) + offset
;
443 #ifdef IS_TRAPPED_INTERNALVAR
444 if (IS_TRAPPED_INTERNALVAR (var
->name
))
445 SET_TRAPPED_INTERNALVAR (var
, newval
, bitpos
, bitsize
, offset
);
449 modify_field (addr
, value_as_long (newval
),
452 memcpy (addr
, VALUE_CONTENTS (newval
), TYPE_LENGTH (VALUE_TYPE (newval
)));
456 set_internalvar (var
, val
)
457 struct internalvar
*var
;
462 #ifdef IS_TRAPPED_INTERNALVAR
463 if (IS_TRAPPED_INTERNALVAR (var
->name
))
464 SET_TRAPPED_INTERNALVAR (var
, val
, 0, 0, 0);
467 newval
= value_copy (val
);
469 /* Force the value to be fetched from the target now, to avoid problems
470 later when this internalvar is referenced and the target is gone or
472 if (VALUE_LAZY (newval
))
473 value_fetch_lazy (newval
);
475 /* Begin code which must not call error(). If var->value points to
476 something free'd, an error() obviously leaves a dangling pointer.
477 But we also get a danling pointer if var->value points to
478 something in the value chain (i.e., before release_value is
479 called), because after the error free_all_values will get called before
481 free ((PTR
)var
->value
);
483 release_value (newval
);
484 /* End code which must not call error(). */
488 internalvar_name (var
)
489 struct internalvar
*var
;
494 /* Free all internalvars. Done when new symtabs are loaded,
495 because that makes the values invalid. */
498 clear_internalvars ()
500 register struct internalvar
*var
;
505 internalvars
= var
->next
;
506 free ((PTR
)var
->name
);
507 free ((PTR
)var
->value
);
513 show_convenience (ignore
, from_tty
)
517 register struct internalvar
*var
;
520 for (var
= internalvars
; var
; var
= var
->next
)
522 #ifdef IS_TRAPPED_INTERNALVAR
523 if (IS_TRAPPED_INTERNALVAR (var
->name
))
530 printf_filtered ("$%s = ", var
->name
);
531 value_print (var
->value
, gdb_stdout
, 0, Val_pretty_default
);
532 printf_filtered ("\n");
535 printf_unfiltered ("No debugger convenience variables now defined.\n\
536 Convenience variables have names starting with \"$\";\n\
537 use \"set\" as in \"set $foo = 5\" to define them.\n");
540 /* Extract a value as a C number (either long or double).
541 Knows how to convert fixed values to double, or
542 floating values to long.
543 Does not deallocate the value. */
547 register value_ptr val
;
549 /* This coerces arrays and functions, which is necessary (e.g.
550 in disassemble_command). It also dereferences references, which
551 I suspect is the most logical thing to do. */
552 if (TYPE_CODE (VALUE_TYPE (val
)) != TYPE_CODE_ENUM
)
554 return unpack_long (VALUE_TYPE (val
), VALUE_CONTENTS (val
));
558 value_as_double (val
)
559 register value_ptr val
;
564 foo
= unpack_double (VALUE_TYPE (val
), VALUE_CONTENTS (val
), &inv
);
566 error ("Invalid floating value found in program.");
569 /* Extract a value as a C pointer.
570 Does not deallocate the value. */
572 value_as_pointer (val
)
575 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
576 whether we want this to be true eventually. */
578 /* ADDR_BITS_REMOVE is wrong if we are being called for a
579 non-address (e.g. argument to "signal", "info break", etc.), or
580 for pointers to char, in which the low bits *are* significant. */
581 return ADDR_BITS_REMOVE(value_as_long (val
));
583 return value_as_long (val
);
587 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
588 as a long, or as a double, assuming the raw data is described
589 by type TYPE. Knows how to convert different sizes of values
590 and can convert between fixed and floating point. We don't assume
591 any alignment for the raw data. Return value is in host byte order.
593 If you want functions and arrays to be coerced to pointers, and
594 references to be dereferenced, call value_as_long() instead.
596 C++: It is assumed that the front-end has taken care of
597 all matters concerning pointers to members. A pointer
598 to member which reaches here is considered to be equivalent
599 to an INT (or some size). After all, it is only an offset. */
601 /* FIXME: This should be rewritten as a switch statement for speed and
602 ease of comprehension. */
605 unpack_long (type
, valaddr
)
609 register enum type_code code
= TYPE_CODE (type
);
610 register int len
= TYPE_LENGTH (type
);
611 register int nosign
= TYPE_UNSIGNED (type
);
619 case TYPE_CODE_RANGE
:
621 return extract_unsigned_integer (valaddr
, len
);
623 return extract_signed_integer (valaddr
, len
);
626 return extract_floating (valaddr
, len
);
630 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
631 whether we want this to be true eventually. */
632 return extract_address (valaddr
, len
);
634 case TYPE_CODE_MEMBER
:
635 error ("not implemented: member types in unpack_long");
638 error ("Value can't be converted to integer.");
640 return 0; /* Placate lint. */
643 /* Return a double value from the specified type and address.
644 INVP points to an int which is set to 0 for valid value,
645 1 for invalid value (bad float format). In either case,
646 the returned double is OK to use. Argument is in target
647 format, result is in host format. */
650 unpack_double (type
, valaddr
, invp
)
655 register enum type_code code
= TYPE_CODE (type
);
656 register int len
= TYPE_LENGTH (type
);
657 register int nosign
= TYPE_UNSIGNED (type
);
659 *invp
= 0; /* Assume valid. */
660 if (code
== TYPE_CODE_FLT
)
662 if (INVALID_FLOAT (valaddr
, len
))
665 return 1.234567891011121314;
667 return extract_floating (valaddr
, len
);
671 /* Unsigned -- be sure we compensate for signed LONGEST. */
672 return (unsigned LONGEST
) unpack_long (type
, valaddr
);
676 /* Signed -- we are OK with unpack_long. */
677 return unpack_long (type
, valaddr
);
681 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
682 as a CORE_ADDR, assuming the raw data is described by type TYPE.
683 We don't assume any alignment for the raw data. Return value is in
686 If you want functions and arrays to be coerced to pointers, and
687 references to be dereferenced, call value_as_pointer() instead.
689 C++: It is assumed that the front-end has taken care of
690 all matters concerning pointers to members. A pointer
691 to member which reaches here is considered to be equivalent
692 to an INT (or some size). After all, it is only an offset. */
695 unpack_pointer (type
, valaddr
)
699 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
700 whether we want this to be true eventually. */
701 return unpack_long (type
, valaddr
);
704 /* Given a value ARG1 (offset by OFFSET bytes)
705 of a struct or union type ARG_TYPE,
706 extract and return the value of one of its fields.
707 FIELDNO says which field.
709 For C++, must also be able to return values from static fields */
712 value_primitive_field (arg1
, offset
, fieldno
, arg_type
)
713 register value_ptr arg1
;
715 register int fieldno
;
716 register struct type
*arg_type
;
718 register value_ptr v
;
719 register struct type
*type
;
721 check_stub_type (arg_type
);
722 type
= TYPE_FIELD_TYPE (arg_type
, fieldno
);
724 /* Handle packed fields */
726 offset
+= TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
727 if (TYPE_FIELD_BITSIZE (arg_type
, fieldno
))
729 v
= value_from_longest (type
,
730 unpack_field_as_long (arg_type
,
731 VALUE_CONTENTS (arg1
),
733 VALUE_BITPOS (v
) = TYPE_FIELD_BITPOS (arg_type
, fieldno
) % 8;
734 VALUE_BITSIZE (v
) = TYPE_FIELD_BITSIZE (arg_type
, fieldno
);
738 v
= allocate_value (type
);
739 if (VALUE_LAZY (arg1
))
742 memcpy (VALUE_CONTENTS_RAW (v
), VALUE_CONTENTS_RAW (arg1
) + offset
,
745 VALUE_LVAL (v
) = VALUE_LVAL (arg1
);
746 if (VALUE_LVAL (arg1
) == lval_internalvar
)
747 VALUE_LVAL (v
) = lval_internalvar_component
;
748 VALUE_ADDRESS (v
) = VALUE_ADDRESS (arg1
);
749 VALUE_OFFSET (v
) = offset
+ VALUE_OFFSET (arg1
);
753 /* Given a value ARG1 of a struct or union type,
754 extract and return the value of one of its fields.
755 FIELDNO says which field.
757 For C++, must also be able to return values from static fields */
760 value_field (arg1
, fieldno
)
761 register value_ptr arg1
;
762 register int fieldno
;
764 return value_primitive_field (arg1
, 0, fieldno
, VALUE_TYPE (arg1
));
767 /* Return a non-virtual function as a value.
768 F is the list of member functions which contains the desired method.
769 J is an index into F which provides the desired method. */
772 value_fn_field (arg1p
, f
, j
, type
, offset
)
779 register value_ptr v
;
780 register struct type
*ftype
= TYPE_FN_FIELD_TYPE (f
, j
);
783 sym
= lookup_symbol (TYPE_FN_FIELD_PHYSNAME (f
, j
),
784 0, VAR_NAMESPACE
, 0, NULL
);
788 error ("Internal error: could not find physical method named %s",
789 TYPE_FN_FIELD_PHYSNAME (f, j));
792 v
= allocate_value (ftype
);
793 VALUE_ADDRESS (v
) = BLOCK_START (SYMBOL_BLOCK_VALUE (sym
));
794 VALUE_TYPE (v
) = ftype
;
798 if (type
!= VALUE_TYPE (*arg1p
))
799 *arg1p
= value_ind (value_cast (lookup_pointer_type (type
),
800 value_addr (*arg1p
)));
802 /* Move the `this' pointer according to the offset.
803 VALUE_OFFSET (*arg1p) += offset;
810 /* Return a virtual function as a value.
811 ARG1 is the object which provides the virtual function
812 table pointer. *ARG1P is side-effected in calling this function.
813 F is the list of member functions which contains the desired virtual
815 J is an index into F which provides the desired virtual function.
817 TYPE is the type in which F is located. */
819 value_virtual_fn_field (arg1p
, f
, j
, type
, offset
)
826 value_ptr arg1
= *arg1p
;
827 /* First, get the virtual function table pointer. That comes
828 with a strange type, so cast it to type `pointer to long' (which
829 should serve just fine as a function type). Then, index into
830 the table, and convert final value to appropriate function type. */
831 value_ptr entry
, vfn
, vtbl
;
832 value_ptr vi
= value_from_longest (builtin_type_int
,
833 (LONGEST
) TYPE_FN_FIELD_VOFFSET (f
, j
));
834 struct type
*fcontext
= TYPE_FN_FIELD_FCONTEXT (f
, j
);
835 struct type
*context
;
836 if (fcontext
== NULL
)
837 /* We don't have an fcontext (e.g. the program was compiled with
838 g++ version 1). Try to get the vtbl from the TYPE_VPTR_BASETYPE.
839 This won't work right for multiple inheritance, but at least we
840 should do as well as GDB 3.x did. */
841 fcontext
= TYPE_VPTR_BASETYPE (type
);
842 context
= lookup_pointer_type (fcontext
);
843 /* Now context is a pointer to the basetype containing the vtbl. */
844 if (TYPE_TARGET_TYPE (context
) != VALUE_TYPE (arg1
))
845 arg1
= value_ind (value_cast (context
, value_addr (arg1
)));
847 context
= VALUE_TYPE (arg1
);
848 /* Now context is the basetype containing the vtbl. */
850 /* This type may have been defined before its virtual function table
851 was. If so, fill in the virtual function table entry for the
853 if (TYPE_VPTR_FIELDNO (context
) < 0)
854 fill_in_vptr_fieldno (context
);
856 /* The virtual function table is now an array of structures
857 which have the form { int16 offset, delta; void *pfn; }. */
858 vtbl
= value_ind (value_primitive_field (arg1
, 0,
859 TYPE_VPTR_FIELDNO (context
),
860 TYPE_VPTR_BASETYPE (context
)));
862 /* Index into the virtual function table. This is hard-coded because
863 looking up a field is not cheap, and it may be important to save
864 time, e.g. if the user has set a conditional breakpoint calling
865 a virtual function. */
866 entry
= value_subscript (vtbl
, vi
);
868 /* Move the `this' pointer according to the virtual function table. */
869 VALUE_OFFSET (arg1
) += value_as_long (value_field (entry
, 0))/* + offset*/;
871 if (! VALUE_LAZY (arg1
))
873 VALUE_LAZY (arg1
) = 1;
874 value_fetch_lazy (arg1
);
877 vfn
= value_field (entry
, 2);
878 /* Reinstantiate the function pointer with the correct type. */
879 VALUE_TYPE (vfn
) = lookup_pointer_type (TYPE_FN_FIELD_TYPE (f
, j
));
885 /* ARG is a pointer to an object we know to be at least
886 a DTYPE. BTYPE is the most derived basetype that has
887 already been searched (and need not be searched again).
888 After looking at the vtables between BTYPE and DTYPE,
889 return the most derived type we find. The caller must
890 be satisfied when the return value == DTYPE.
892 FIXME-tiemann: should work with dossier entries as well. */
895 value_headof (in_arg
, btype
, dtype
)
897 struct type
*btype
, *dtype
;
899 /* First collect the vtables we must look at for this object. */
900 /* FIXME-tiemann: right now, just look at top-most vtable. */
901 value_ptr arg
, vtbl
, entry
, best_entry
= 0;
903 int offset
, best_offset
= 0;
905 CORE_ADDR pc_for_sym
;
906 char *demangled_name
;
907 struct minimal_symbol
*msymbol
;
909 btype
= TYPE_VPTR_BASETYPE (dtype
);
910 check_stub_type (btype
);
913 arg
= value_cast (lookup_pointer_type (btype
), arg
);
914 vtbl
= value_ind (value_field (value_ind (arg
), TYPE_VPTR_FIELDNO (btype
)));
916 /* Check that VTBL looks like it points to a virtual function table. */
917 msymbol
= lookup_minimal_symbol_by_pc (VALUE_ADDRESS (vtbl
));
919 || !VTBL_PREFIX_P (demangled_name
= SYMBOL_NAME (msymbol
)))
921 /* If we expected to find a vtable, but did not, let the user
922 know that we aren't happy, but don't throw an error.
923 FIXME: there has to be a better way to do this. */
924 struct type
*error_type
= (struct type
*)xmalloc (sizeof (struct type
));
925 memcpy (error_type
, VALUE_TYPE (in_arg
), sizeof (struct type
));
926 TYPE_NAME (error_type
) = savestring ("suspicious *", sizeof ("suspicious *"));
927 VALUE_TYPE (in_arg
) = error_type
;
931 /* Now search through the virtual function table. */
932 entry
= value_ind (vtbl
);
933 nelems
= longest_to_int (value_as_long (value_field (entry
, 2)));
934 for (i
= 1; i
<= nelems
; i
++)
936 entry
= value_subscript (vtbl
, value_from_longest (builtin_type_int
,
938 offset
= longest_to_int (value_as_long (value_field (entry
, 0)));
939 /* If we use '<=' we can handle single inheritance
940 * where all offsets are zero - just use the first entry found. */
941 if (offset
<= best_offset
)
943 best_offset
= offset
;
947 /* Move the pointer according to BEST_ENTRY's offset, and figure
948 out what type we should return as the new pointer. */
951 /* An alternative method (which should no longer be necessary).
952 * But we leave it in for future use, when we will hopefully
953 * have optimizes the vtable to use thunks instead of offsets. */
954 /* Use the name of vtable itself to extract a base type. */
955 demangled_name
+= 4; /* Skip _vt$ prefix. */
959 pc_for_sym
= value_as_pointer (value_field (best_entry
, 2));
960 sym
= find_pc_function (pc_for_sym
);
961 demangled_name
= cplus_demangle (SYMBOL_NAME (sym
), DMGL_ANSI
);
962 *(strchr (demangled_name
, ':')) = '\0';
964 sym
= lookup_symbol (demangled_name
, 0, VAR_NAMESPACE
, 0, 0);
966 error ("could not find type declaration for `%s'", demangled_name
);
969 free (demangled_name
);
970 arg
= value_add (value_cast (builtin_type_int
, arg
),
971 value_field (best_entry
, 0));
974 VALUE_TYPE (arg
) = lookup_pointer_type (SYMBOL_TYPE (sym
));
978 /* ARG is a pointer object of type TYPE. If TYPE has virtual
979 function tables, probe ARG's tables (including the vtables
980 of its baseclasses) to figure out the most derived type that ARG
981 could actually be a pointer to. */
984 value_from_vtable_info (arg
, type
)
988 /* Take care of preliminaries. */
989 if (TYPE_VPTR_FIELDNO (type
) < 0)
990 fill_in_vptr_fieldno (type
);
991 if (TYPE_VPTR_FIELDNO (type
) < 0 || VALUE_REPEATED (arg
))
994 return value_headof (arg
, 0, type
);
997 /* Return true if the INDEXth field of TYPE is a virtual baseclass
998 pointer which is for the base class whose type is BASECLASS. */
1001 vb_match (type
, index
, basetype
)
1004 struct type
*basetype
;
1006 struct type
*fieldtype
;
1007 char *name
= TYPE_FIELD_NAME (type
, index
);
1008 char *field_class_name
= NULL
;
1012 /* gcc 2.4 uses _vb$. */
1013 if (name
[1] == 'v' && name
[2] == 'b' && name
[3] == CPLUS_MARKER
)
1014 field_class_name
= name
+ 4;
1015 /* gcc 2.5 will use __vb_. */
1016 if (name
[1] == '_' && name
[2] == 'v' && name
[3] == 'b' && name
[4] == '_')
1017 field_class_name
= name
+ 5;
1019 if (field_class_name
== NULL
)
1020 /* This field is not a virtual base class pointer. */
1023 /* It's a virtual baseclass pointer, now we just need to find out whether
1024 it is for this baseclass. */
1025 fieldtype
= TYPE_FIELD_TYPE (type
, index
);
1026 if (fieldtype
== NULL
1027 || TYPE_CODE (fieldtype
) != TYPE_CODE_PTR
)
1028 /* "Can't happen". */
1031 /* What we check for is that either the types are equal (needed for
1032 nameless types) or have the same name. This is ugly, and a more
1033 elegant solution should be devised (which would probably just push
1034 the ugliness into symbol reading unless we change the stabs format). */
1035 if (TYPE_TARGET_TYPE (fieldtype
) == basetype
)
1038 if (TYPE_NAME (basetype
) != NULL
1039 && TYPE_NAME (TYPE_TARGET_TYPE (fieldtype
)) != NULL
1040 && STREQ (TYPE_NAME (basetype
),
1041 TYPE_NAME (TYPE_TARGET_TYPE (fieldtype
))))
1046 /* Compute the offset of the baseclass which is
1047 the INDEXth baseclass of class TYPE, for a value ARG,
1048 wih extra offset of OFFSET.
1049 The result is the offste of the baseclass value relative
1050 to (the address of)(ARG) + OFFSET.
1052 -1 is returned on error. */
1055 baseclass_offset (type
, index
, arg
, offset
)
1061 struct type
*basetype
= TYPE_BASECLASS (type
, index
);
1063 if (BASETYPE_VIA_VIRTUAL (type
, index
))
1065 /* Must hunt for the pointer to this virtual baseclass. */
1066 register int i
, len
= TYPE_NFIELDS (type
);
1067 register int n_baseclasses
= TYPE_N_BASECLASSES (type
);
1069 /* First look for the virtual baseclass pointer
1071 for (i
= n_baseclasses
; i
< len
; i
++)
1073 if (vb_match (type
, i
, basetype
))
1076 = unpack_pointer (TYPE_FIELD_TYPE (type
, i
),
1077 VALUE_CONTENTS (arg
) + VALUE_OFFSET (arg
)
1079 + (TYPE_FIELD_BITPOS (type
, i
) / 8));
1081 if (VALUE_LVAL (arg
) != lval_memory
)
1085 (LONGEST
) (VALUE_ADDRESS (arg
) + VALUE_OFFSET (arg
) + offset
);
1088 /* Not in the fields, so try looking through the baseclasses. */
1089 for (i
= index
+1; i
< n_baseclasses
; i
++)
1092 baseclass_offset (type
, i
, arg
, offset
);
1100 /* Baseclass is easily computed. */
1101 return TYPE_BASECLASS_BITPOS (type
, index
) / 8;
1104 /* Compute the address of the baseclass which is
1105 the INDEXth baseclass of class TYPE. The TYPE base
1106 of the object is at VALADDR.
1108 If ERRP is non-NULL, set *ERRP to be the errno code of any error,
1109 or 0 if no error. In that case the return value is not the address
1110 of the baseclasss, but the address which could not be read
1113 /* FIXME Fix remaining uses of baseclass_addr to use baseclass_offset */
1116 baseclass_addr (type
, index
, valaddr
, valuep
, errp
)
1123 struct type
*basetype
= TYPE_BASECLASS (type
, index
);
1128 if (BASETYPE_VIA_VIRTUAL (type
, index
))
1130 /* Must hunt for the pointer to this virtual baseclass. */
1131 register int i
, len
= TYPE_NFIELDS (type
);
1132 register int n_baseclasses
= TYPE_N_BASECLASSES (type
);
1134 /* First look for the virtual baseclass pointer
1136 for (i
= n_baseclasses
; i
< len
; i
++)
1138 if (vb_match (type
, i
, basetype
))
1140 value_ptr val
= allocate_value (basetype
);
1145 = unpack_pointer (TYPE_FIELD_TYPE (type
, i
),
1146 valaddr
+ (TYPE_FIELD_BITPOS (type
, i
) / 8));
1148 status
= target_read_memory (addr
,
1149 VALUE_CONTENTS_RAW (val
),
1150 TYPE_LENGTH (basetype
));
1151 VALUE_LVAL (val
) = lval_memory
;
1152 VALUE_ADDRESS (val
) = addr
;
1158 release_value (val
);
1162 return (char *)addr
;
1168 return (char *) VALUE_CONTENTS (val
);
1172 /* Not in the fields, so try looking through the baseclasses. */
1173 for (i
= index
+1; i
< n_baseclasses
; i
++)
1177 baddr
= baseclass_addr (type
, i
, valaddr
, valuep
, errp
);
1187 /* Baseclass is easily computed. */
1190 return valaddr
+ TYPE_BASECLASS_BITPOS (type
, index
) / 8;
1193 /* Unpack a field FIELDNO of the specified TYPE, from the anonymous object at
1196 Extracting bits depends on endianness of the machine. Compute the
1197 number of least significant bits to discard. For big endian machines,
1198 we compute the total number of bits in the anonymous object, subtract
1199 off the bit count from the MSB of the object to the MSB of the
1200 bitfield, then the size of the bitfield, which leaves the LSB discard
1201 count. For little endian machines, the discard count is simply the
1202 number of bits from the LSB of the anonymous object to the LSB of the
1205 If the field is signed, we also do sign extension. */
1208 unpack_field_as_long (type
, valaddr
, fieldno
)
1213 unsigned LONGEST val
;
1214 unsigned LONGEST valmask
;
1215 int bitpos
= TYPE_FIELD_BITPOS (type
, fieldno
);
1216 int bitsize
= TYPE_FIELD_BITSIZE (type
, fieldno
);
1219 val
= extract_unsigned_integer (valaddr
+ bitpos
/ 8, sizeof (val
));
1221 /* Extract bits. See comment above. */
1224 lsbcount
= (sizeof val
* 8 - bitpos
% 8 - bitsize
);
1226 lsbcount
= (bitpos
% 8);
1230 /* If the field does not entirely fill a LONGEST, then zero the sign bits.
1231 If the field is signed, and is negative, then sign extend. */
1233 if ((bitsize
> 0) && (bitsize
< 8 * sizeof (val
)))
1235 valmask
= (((unsigned LONGEST
) 1) << bitsize
) - 1;
1237 if (!TYPE_UNSIGNED (TYPE_FIELD_TYPE (type
, fieldno
)))
1239 if (val
& (valmask
^ (valmask
>> 1)))
1248 /* Modify the value of a bitfield. ADDR points to a block of memory in
1249 target byte order; the bitfield starts in the byte pointed to. FIELDVAL
1250 is the desired value of the field, in host byte order. BITPOS and BITSIZE
1251 indicate which bits (in target bit order) comprise the bitfield. */
1254 modify_field (addr
, fieldval
, bitpos
, bitsize
)
1257 int bitpos
, bitsize
;
1261 /* Reject values too big to fit in the field in question,
1262 otherwise adjoining fields may be corrupted. */
1263 if (bitsize
< (8 * sizeof (fieldval
))
1264 && 0 != (fieldval
& ~((1<<bitsize
)-1)))
1266 /* FIXME: would like to include fieldval in the message, but
1267 we don't have a sprintf_longest. */
1268 error ("Value does not fit in %d bits.", bitsize
);
1271 oword
= extract_signed_integer (addr
, sizeof oword
);
1273 /* Shifting for bit field depends on endianness of the target machine. */
1275 bitpos
= sizeof (oword
) * 8 - bitpos
- bitsize
;
1278 /* Mask out old value, while avoiding shifts >= size of oword */
1279 if (bitsize
< 8 * sizeof (oword
))
1280 oword
&= ~(((((unsigned LONGEST
)1) << bitsize
) - 1) << bitpos
);
1282 oword
&= ~((~(unsigned LONGEST
)0) << bitpos
);
1283 oword
|= fieldval
<< bitpos
;
1285 store_signed_integer (addr
, sizeof oword
, oword
);
1288 /* Convert C numbers into newly allocated values */
1291 value_from_longest (type
, num
)
1293 register LONGEST num
;
1295 register value_ptr val
= allocate_value (type
);
1296 register enum type_code code
= TYPE_CODE (type
);
1297 register int len
= TYPE_LENGTH (type
);
1302 case TYPE_CODE_CHAR
:
1303 case TYPE_CODE_ENUM
:
1304 case TYPE_CODE_BOOL
:
1305 case TYPE_CODE_RANGE
:
1306 store_signed_integer (VALUE_CONTENTS_RAW (val
), len
, num
);
1311 /* This assumes that all pointers of a given length
1312 have the same form. */
1313 store_address (VALUE_CONTENTS_RAW (val
), len
, (CORE_ADDR
) num
);
1317 error ("Unexpected type encountered for integer constant.");
1323 value_from_double (type
, num
)
1327 register value_ptr val
= allocate_value (type
);
1328 register enum type_code code
= TYPE_CODE (type
);
1329 register int len
= TYPE_LENGTH (type
);
1331 if (code
== TYPE_CODE_FLT
)
1333 store_floating (VALUE_CONTENTS_RAW (val
), len
, num
);
1336 error ("Unexpected type encountered for floating constant.");
1341 /* Deal with the value that is "about to be returned". */
1343 /* Return the value that a function returning now
1344 would be returning to its caller, assuming its type is VALTYPE.
1345 RETBUF is where we look for what ought to be the contents
1346 of the registers (in raw form). This is because it is often
1347 desirable to restore old values to those registers
1348 after saving the contents of interest, and then call
1349 this function using the saved values.
1350 struct_return is non-zero when the function in question is
1351 using the structure return conventions on the machine in question;
1352 0 when it is using the value returning conventions (this often
1353 means returning pointer to where structure is vs. returning value). */
1356 value_being_returned (valtype
, retbuf
, struct_return
)
1357 register struct type
*valtype
;
1358 char retbuf
[REGISTER_BYTES
];
1362 register value_ptr val
;
1365 #if defined (EXTRACT_STRUCT_VALUE_ADDRESS)
1366 /* If this is not defined, just use EXTRACT_RETURN_VALUE instead. */
1367 if (struct_return
) {
1368 addr
= EXTRACT_STRUCT_VALUE_ADDRESS (retbuf
);
1370 error ("Function return value unknown");
1371 return value_at (valtype
, addr
);
1375 val
= allocate_value (valtype
);
1376 EXTRACT_RETURN_VALUE (valtype
, retbuf
, VALUE_CONTENTS_RAW (val
));
1381 /* Should we use EXTRACT_STRUCT_VALUE_ADDRESS instead of
1382 EXTRACT_RETURN_VALUE? GCC_P is true if compiled with gcc
1383 and TYPE is the type (which is known to be struct, union or array).
1385 On most machines, the struct convention is used unless we are
1386 using gcc and the type is of a special size. */
1387 /* As of about 31 Mar 93, GCC was changed to be compatible with the
1388 native compiler. GCC 2.3.3 was the last release that did it the
1389 old way. Since gcc2_compiled was not changed, we have no
1390 way to correctly win in all cases, so we just do the right thing
1391 for gcc1 and for gcc2 after this change. Thus it loses for gcc
1392 2.0-2.3.3. This is somewhat unfortunate, but changing gcc2_compiled
1393 would cause more chaos than dealing with some struct returns being
1395 #if !defined (USE_STRUCT_CONVENTION)
1396 #define USE_STRUCT_CONVENTION(gcc_p, type)\
1397 (!((gcc_p == 1) && (TYPE_LENGTH (value_type) == 1 \
1398 || TYPE_LENGTH (value_type) == 2 \
1399 || TYPE_LENGTH (value_type) == 4 \
1400 || TYPE_LENGTH (value_type) == 8 \
1405 /* Return true if the function specified is using the structure returning
1406 convention on this machine to return arguments, or 0 if it is using
1407 the value returning convention. FUNCTION is the value representing
1408 the function, FUNCADDR is the address of the function, and VALUE_TYPE
1409 is the type returned by the function. GCC_P is nonzero if compiled
1413 using_struct_return (function
, funcaddr
, value_type
, gcc_p
)
1416 struct type
*value_type
;
1420 register enum type_code code
= TYPE_CODE (value_type
);
1422 if (code
== TYPE_CODE_ERROR
)
1423 error ("Function return type unknown.");
1425 if (code
== TYPE_CODE_STRUCT
||
1426 code
== TYPE_CODE_UNION
||
1427 code
== TYPE_CODE_ARRAY
)
1428 return USE_STRUCT_CONVENTION (gcc_p
, value_type
);
1433 /* Store VAL so it will be returned if a function returns now.
1434 Does not verify that VAL's type matches what the current
1435 function wants to return. */
1438 set_return_value (val
)
1441 register enum type_code code
= TYPE_CODE (VALUE_TYPE (val
));
1445 if (code
== TYPE_CODE_ERROR
)
1446 error ("Function return type unknown.");
1448 if ( code
== TYPE_CODE_STRUCT
1449 || code
== TYPE_CODE_UNION
) /* FIXME, implement struct return. */
1450 error ("GDB does not support specifying a struct or union return value.");
1452 /* FIXME, this is bogus. We don't know what the return conventions
1453 are, or how values should be promoted.... */
1454 if (code
== TYPE_CODE_FLT
)
1456 dbuf
= value_as_double (val
);
1458 STORE_RETURN_VALUE (VALUE_TYPE (val
), (char *)&dbuf
);
1462 lbuf
= value_as_long (val
);
1463 STORE_RETURN_VALUE (VALUE_TYPE (val
), (char *)&lbuf
);
1468 _initialize_values ()
1470 add_cmd ("convenience", no_class
, show_convenience
,
1471 "Debugger convenience (\"$foo\") variables.\n\
1472 These variables are created when you assign them values;\n\
1473 thus, \"print $foo=1\" gives \"$foo\" the value 1. Values may be any type.\n\n\
1474 A few convenience variables are given values automatically:\n\
1475 \"$_\"holds the last address examined with \"x\" or \"info lines\",\n\
1476 \"$__\" holds the contents of the last address examined with \"x\".",
1479 add_cmd ("values", no_class
, show_values
,
1480 "Elements of value history around item number IDX (or last ten).",