1 /* Low level packing and unpacking of values for GDB, the GNU Debugger.
2 Copyright 1986, 1987, 1989, 1991, 1993, 1994, 1995
3 Free Software Foundation, Inc.
5 This file is part of GDB.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, write to the Free Software
19 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
22 #include "gdb_string.h"
34 /* Local function prototypes. */
36 static value_ptr value_headof
PARAMS ((value_ptr
, struct type
*,
39 static void show_values
PARAMS ((char *, int));
41 static void show_convenience
PARAMS ((char *, int));
43 /* The value-history records all the values printed
44 by print commands during this session. Each chunk
45 records 60 consecutive values. The first chunk on
46 the chain records the most recent values.
47 The total number of values is in value_history_count. */
49 #define VALUE_HISTORY_CHUNK 60
51 struct value_history_chunk
53 struct value_history_chunk
*next
;
54 value_ptr values
[VALUE_HISTORY_CHUNK
];
57 /* Chain of chunks now in use. */
59 static struct value_history_chunk
*value_history_chain
;
61 static int value_history_count
; /* Abs number of last entry stored */
63 /* List of all value objects currently allocated
64 (except for those released by calls to release_value)
65 This is so they can be freed after each command. */
67 static value_ptr all_values
;
69 /* Allocate a value that has the correct length for type TYPE. */
75 register value_ptr val
;
76 struct type
*atype
= check_typedef (type
);
78 val
= (struct value
*) xmalloc (sizeof (struct value
) + TYPE_LENGTH (atype
));
79 VALUE_NEXT (val
) = all_values
;
81 VALUE_TYPE (val
) = type
;
82 VALUE_LVAL (val
) = not_lval
;
83 VALUE_ADDRESS (val
) = 0;
84 VALUE_FRAME (val
) = 0;
85 VALUE_OFFSET (val
) = 0;
86 VALUE_BITPOS (val
) = 0;
87 VALUE_BITSIZE (val
) = 0;
88 VALUE_REGNO (val
) = -1;
90 VALUE_OPTIMIZED_OUT (val
) = 0;
95 /* Allocate a value that has the correct length
96 for COUNT repetitions type TYPE. */
99 allocate_repeat_value (type
, count
)
103 struct type
*element_type
= type
;
104 int low_bound
= current_language
->string_lower_bound
; /* ??? */
105 /* FIXME-type-allocation: need a way to free this type when we are
107 struct type
*range_type
108 = create_range_type ((struct type
*) NULL
, builtin_type_int
,
109 low_bound
, count
+ low_bound
- 1);
110 /* FIXME-type-allocation: need a way to free this type when we are
112 return allocate_value (create_array_type ((struct type
*) NULL
,
116 /* Return a mark in the value chain. All values allocated after the
117 mark is obtained (except for those released) are subject to being freed
118 if a subsequent value_free_to_mark is passed the mark. */
125 /* Free all values allocated since MARK was obtained by value_mark
126 (except for those released). */
128 value_free_to_mark (mark
)
133 for (val
= all_values
; val
&& val
!= mark
; val
= next
)
135 next
= VALUE_NEXT (val
);
141 /* Free all the values that have been allocated (except for those released).
142 Called after each command, successful or not. */
147 register value_ptr val
, next
;
149 for (val
= all_values
; val
; val
= next
)
151 next
= VALUE_NEXT (val
);
158 /* Remove VAL from the chain all_values
159 so it will not be freed automatically. */
163 register value_ptr val
;
165 register value_ptr v
;
167 if (all_values
== val
)
169 all_values
= val
->next
;
173 for (v
= all_values
; v
; v
= v
->next
)
183 /* Release all values up to mark */
185 value_release_to_mark (mark
)
190 for (val
= next
= all_values
; next
; next
= VALUE_NEXT (next
))
191 if (VALUE_NEXT (next
) == mark
)
193 all_values
= VALUE_NEXT (next
);
194 VALUE_NEXT (next
) = 0;
201 /* Return a copy of the value ARG.
202 It contains the same contents, for same memory address,
203 but it's a different block of storage. */
209 register struct type
*type
= VALUE_TYPE (arg
);
210 register value_ptr val
= allocate_value (type
);
211 VALUE_LVAL (val
) = VALUE_LVAL (arg
);
212 VALUE_ADDRESS (val
) = VALUE_ADDRESS (arg
);
213 VALUE_OFFSET (val
) = VALUE_OFFSET (arg
);
214 VALUE_BITPOS (val
) = VALUE_BITPOS (arg
);
215 VALUE_BITSIZE (val
) = VALUE_BITSIZE (arg
);
216 VALUE_FRAME (val
) = VALUE_FRAME (arg
);
217 VALUE_REGNO (val
) = VALUE_REGNO (arg
);
218 VALUE_LAZY (val
) = VALUE_LAZY (arg
);
219 VALUE_OPTIMIZED_OUT (val
) = VALUE_OPTIMIZED_OUT (arg
);
220 val
->modifiable
= arg
->modifiable
;
221 if (!VALUE_LAZY (val
))
223 memcpy (VALUE_CONTENTS_RAW (val
), VALUE_CONTENTS_RAW (arg
),
224 TYPE_LENGTH (VALUE_TYPE (arg
)));
229 /* Access to the value history. */
231 /* Record a new value in the value history.
232 Returns the absolute history index of the entry.
233 Result of -1 indicates the value was not saved; otherwise it is the
234 value history index of this new item. */
237 record_latest_value (val
)
242 /* Check error now if about to store an invalid float. We return -1
243 to the caller, but allow them to continue, e.g. to print it as "Nan". */
244 if (TYPE_CODE (VALUE_TYPE (val
)) == TYPE_CODE_FLT
)
246 unpack_double (VALUE_TYPE (val
), VALUE_CONTENTS (val
), &i
);
247 if (i
) return -1; /* Indicate value not saved in history */
250 /* We don't want this value to have anything to do with the inferior anymore.
251 In particular, "set $1 = 50" should not affect the variable from which
252 the value was taken, and fast watchpoints should be able to assume that
253 a value on the value history never changes. */
254 if (VALUE_LAZY (val
))
255 value_fetch_lazy (val
);
256 /* We preserve VALUE_LVAL so that the user can find out where it was fetched
257 from. This is a bit dubious, because then *&$1 does not just return $1
258 but the current contents of that location. c'est la vie... */
262 /* Here we treat value_history_count as origin-zero
263 and applying to the value being stored now. */
265 i
= value_history_count
% VALUE_HISTORY_CHUNK
;
268 register struct value_history_chunk
*new
269 = (struct value_history_chunk
*)
270 xmalloc (sizeof (struct value_history_chunk
));
271 memset (new->values
, 0, sizeof new->values
);
272 new->next
= value_history_chain
;
273 value_history_chain
= new;
276 value_history_chain
->values
[i
] = val
;
278 /* Now we regard value_history_count as origin-one
279 and applying to the value just stored. */
281 return ++value_history_count
;
284 /* Return a copy of the value in the history with sequence number NUM. */
287 access_value_history (num
)
290 register struct value_history_chunk
*chunk
;
292 register int absnum
= num
;
295 absnum
+= value_history_count
;
300 error ("The history is empty.");
302 error ("There is only one value in the history.");
304 error ("History does not go back to $$%d.", -num
);
306 if (absnum
> value_history_count
)
307 error ("History has not yet reached $%d.", absnum
);
311 /* Now absnum is always absolute and origin zero. */
313 chunk
= value_history_chain
;
314 for (i
= (value_history_count
- 1) / VALUE_HISTORY_CHUNK
- absnum
/ VALUE_HISTORY_CHUNK
;
318 return value_copy (chunk
->values
[absnum
% VALUE_HISTORY_CHUNK
]);
321 /* Clear the value history entirely.
322 Must be done when new symbol tables are loaded,
323 because the type pointers become invalid. */
326 clear_value_history ()
328 register struct value_history_chunk
*next
;
330 register value_ptr val
;
332 while (value_history_chain
)
334 for (i
= 0; i
< VALUE_HISTORY_CHUNK
; i
++)
335 if ((val
= value_history_chain
->values
[i
]) != NULL
)
337 next
= value_history_chain
->next
;
338 free ((PTR
)value_history_chain
);
339 value_history_chain
= next
;
341 value_history_count
= 0;
345 show_values (num_exp
, from_tty
)
350 register value_ptr val
;
355 /* "info history +" should print from the stored position.
356 "info history <exp>" should print around value number <exp>. */
357 if (num_exp
[0] != '+' || num_exp
[1] != '\0')
358 num
= parse_and_eval_address (num_exp
) - 5;
362 /* "info history" means print the last 10 values. */
363 num
= value_history_count
- 9;
369 for (i
= num
; i
< num
+ 10 && i
<= value_history_count
; i
++)
371 val
= access_value_history (i
);
372 printf_filtered ("$%d = ", i
);
373 value_print (val
, gdb_stdout
, 0, Val_pretty_default
);
374 printf_filtered ("\n");
377 /* The next "info history +" should start after what we just printed. */
380 /* Hitting just return after this command should do the same thing as
381 "info history +". If num_exp is null, this is unnecessary, since
382 "info history +" is not useful after "info history". */
383 if (from_tty
&& num_exp
)
390 /* Internal variables. These are variables within the debugger
391 that hold values assigned by debugger commands.
392 The user refers to them with a '$' prefix
393 that does not appear in the variable names stored internally. */
395 static struct internalvar
*internalvars
;
397 /* Look up an internal variable with name NAME. NAME should not
398 normally include a dollar sign.
400 If the specified internal variable does not exist,
401 one is created, with a void value. */
404 lookup_internalvar (name
)
407 register struct internalvar
*var
;
409 for (var
= internalvars
; var
; var
= var
->next
)
410 if (STREQ (var
->name
, name
))
413 var
= (struct internalvar
*) xmalloc (sizeof (struct internalvar
));
414 var
->name
= concat (name
, NULL
);
415 var
->value
= allocate_value (builtin_type_void
);
416 release_value (var
->value
);
417 var
->next
= internalvars
;
423 value_of_internalvar (var
)
424 struct internalvar
*var
;
426 register value_ptr val
;
428 #ifdef IS_TRAPPED_INTERNALVAR
429 if (IS_TRAPPED_INTERNALVAR (var
->name
))
430 return VALUE_OF_TRAPPED_INTERNALVAR (var
);
433 val
= value_copy (var
->value
);
434 if (VALUE_LAZY (val
))
435 value_fetch_lazy (val
);
436 VALUE_LVAL (val
) = lval_internalvar
;
437 VALUE_INTERNALVAR (val
) = var
;
442 set_internalvar_component (var
, offset
, bitpos
, bitsize
, newval
)
443 struct internalvar
*var
;
444 int offset
, bitpos
, bitsize
;
447 register char *addr
= VALUE_CONTENTS (var
->value
) + offset
;
449 #ifdef IS_TRAPPED_INTERNALVAR
450 if (IS_TRAPPED_INTERNALVAR (var
->name
))
451 SET_TRAPPED_INTERNALVAR (var
, newval
, bitpos
, bitsize
, offset
);
455 modify_field (addr
, value_as_long (newval
),
458 memcpy (addr
, VALUE_CONTENTS (newval
), TYPE_LENGTH (VALUE_TYPE (newval
)));
462 set_internalvar (var
, val
)
463 struct internalvar
*var
;
468 #ifdef IS_TRAPPED_INTERNALVAR
469 if (IS_TRAPPED_INTERNALVAR (var
->name
))
470 SET_TRAPPED_INTERNALVAR (var
, val
, 0, 0, 0);
473 newval
= value_copy (val
);
474 newval
->modifiable
= 1;
476 /* Force the value to be fetched from the target now, to avoid problems
477 later when this internalvar is referenced and the target is gone or
479 if (VALUE_LAZY (newval
))
480 value_fetch_lazy (newval
);
482 /* Begin code which must not call error(). If var->value points to
483 something free'd, an error() obviously leaves a dangling pointer.
484 But we also get a danling pointer if var->value points to
485 something in the value chain (i.e., before release_value is
486 called), because after the error free_all_values will get called before
488 free ((PTR
)var
->value
);
490 release_value (newval
);
491 /* End code which must not call error(). */
495 internalvar_name (var
)
496 struct internalvar
*var
;
501 /* Free all internalvars. Done when new symtabs are loaded,
502 because that makes the values invalid. */
505 clear_internalvars ()
507 register struct internalvar
*var
;
512 internalvars
= var
->next
;
513 free ((PTR
)var
->name
);
514 free ((PTR
)var
->value
);
520 show_convenience (ignore
, from_tty
)
524 register struct internalvar
*var
;
527 for (var
= internalvars
; var
; var
= var
->next
)
529 #ifdef IS_TRAPPED_INTERNALVAR
530 if (IS_TRAPPED_INTERNALVAR (var
->name
))
537 printf_filtered ("$%s = ", var
->name
);
538 value_print (var
->value
, gdb_stdout
, 0, Val_pretty_default
);
539 printf_filtered ("\n");
542 printf_unfiltered ("No debugger convenience variables now defined.\n\
543 Convenience variables have names starting with \"$\";\n\
544 use \"set\" as in \"set $foo = 5\" to define them.\n");
547 /* Extract a value as a C number (either long or double).
548 Knows how to convert fixed values to double, or
549 floating values to long.
550 Does not deallocate the value. */
554 register value_ptr val
;
556 /* This coerces arrays and functions, which is necessary (e.g.
557 in disassemble_command). It also dereferences references, which
558 I suspect is the most logical thing to do. */
559 if (TYPE_CODE (VALUE_TYPE (val
)) != TYPE_CODE_ENUM
)
561 return unpack_long (VALUE_TYPE (val
), VALUE_CONTENTS (val
));
565 value_as_double (val
)
566 register value_ptr val
;
571 foo
= unpack_double (VALUE_TYPE (val
), VALUE_CONTENTS (val
), &inv
);
573 error ("Invalid floating value found in program.");
576 /* Extract a value as a C pointer.
577 Does not deallocate the value. */
579 value_as_pointer (val
)
582 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
583 whether we want this to be true eventually. */
585 /* ADDR_BITS_REMOVE is wrong if we are being called for a
586 non-address (e.g. argument to "signal", "info break", etc.), or
587 for pointers to char, in which the low bits *are* significant. */
588 return ADDR_BITS_REMOVE(value_as_long (val
));
590 return value_as_long (val
);
594 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
595 as a long, or as a double, assuming the raw data is described
596 by type TYPE. Knows how to convert different sizes of values
597 and can convert between fixed and floating point. We don't assume
598 any alignment for the raw data. Return value is in host byte order.
600 If you want functions and arrays to be coerced to pointers, and
601 references to be dereferenced, call value_as_long() instead.
603 C++: It is assumed that the front-end has taken care of
604 all matters concerning pointers to members. A pointer
605 to member which reaches here is considered to be equivalent
606 to an INT (or some size). After all, it is only an offset. */
609 unpack_long (type
, valaddr
)
613 register enum type_code code
= TYPE_CODE (type
);
614 register int len
= TYPE_LENGTH (type
);
615 register int nosign
= TYPE_UNSIGNED (type
);
617 if (current_language
->la_language
== language_scm
618 && is_scmvalue_type (type
))
619 return scm_unpack (type
, valaddr
, TYPE_CODE_INT
);
623 case TYPE_CODE_TYPEDEF
:
624 return unpack_long (check_typedef (type
), valaddr
);
629 case TYPE_CODE_RANGE
:
631 return extract_unsigned_integer (valaddr
, len
);
633 return extract_signed_integer (valaddr
, len
);
636 return extract_floating (valaddr
, len
);
640 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
641 whether we want this to be true eventually. */
642 return extract_address (valaddr
, len
);
644 case TYPE_CODE_MEMBER
:
645 error ("not implemented: member types in unpack_long");
648 error ("Value can't be converted to integer.");
650 return 0; /* Placate lint. */
653 /* Return a double value from the specified type and address.
654 INVP points to an int which is set to 0 for valid value,
655 1 for invalid value (bad float format). In either case,
656 the returned double is OK to use. Argument is in target
657 format, result is in host format. */
660 unpack_double (type
, valaddr
, invp
)
665 register enum type_code code
= TYPE_CODE (type
);
666 register int len
= TYPE_LENGTH (type
);
667 register int nosign
= TYPE_UNSIGNED (type
);
669 *invp
= 0; /* Assume valid. */
670 CHECK_TYPEDEF (type
);
671 if (code
== TYPE_CODE_FLT
)
674 if (INVALID_FLOAT (valaddr
, len
))
677 return 1.234567891011121314;
680 return extract_floating (valaddr
, len
);
684 /* Unsigned -- be sure we compensate for signed LONGEST. */
685 return (unsigned LONGEST
) unpack_long (type
, valaddr
);
689 /* Signed -- we are OK with unpack_long. */
690 return unpack_long (type
, valaddr
);
694 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
695 as a CORE_ADDR, assuming the raw data is described by type TYPE.
696 We don't assume any alignment for the raw data. Return value is in
699 If you want functions and arrays to be coerced to pointers, and
700 references to be dereferenced, call value_as_pointer() instead.
702 C++: It is assumed that the front-end has taken care of
703 all matters concerning pointers to members. A pointer
704 to member which reaches here is considered to be equivalent
705 to an INT (or some size). After all, it is only an offset. */
708 unpack_pointer (type
, valaddr
)
712 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
713 whether we want this to be true eventually. */
714 return unpack_long (type
, valaddr
);
717 /* Given a value ARG1 (offset by OFFSET bytes)
718 of a struct or union type ARG_TYPE,
719 extract and return the value of one of its fields.
720 FIELDNO says which field.
722 For C++, must also be able to return values from static fields */
725 value_primitive_field (arg1
, offset
, fieldno
, arg_type
)
726 register value_ptr arg1
;
728 register int fieldno
;
729 register struct type
*arg_type
;
731 register value_ptr v
;
732 register struct type
*type
;
734 CHECK_TYPEDEF (arg_type
);
735 type
= TYPE_FIELD_TYPE (arg_type
, fieldno
);
737 /* Handle packed fields */
739 offset
+= TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
740 if (TYPE_FIELD_BITSIZE (arg_type
, fieldno
))
742 v
= value_from_longest (type
,
743 unpack_field_as_long (arg_type
,
744 VALUE_CONTENTS (arg1
),
746 VALUE_BITPOS (v
) = TYPE_FIELD_BITPOS (arg_type
, fieldno
) % 8;
747 VALUE_BITSIZE (v
) = TYPE_FIELD_BITSIZE (arg_type
, fieldno
);
751 v
= allocate_value (type
);
752 if (VALUE_LAZY (arg1
))
755 memcpy (VALUE_CONTENTS_RAW (v
), VALUE_CONTENTS_RAW (arg1
) + offset
,
758 VALUE_LVAL (v
) = VALUE_LVAL (arg1
);
759 if (VALUE_LVAL (arg1
) == lval_internalvar
)
760 VALUE_LVAL (v
) = lval_internalvar_component
;
761 VALUE_ADDRESS (v
) = VALUE_ADDRESS (arg1
);
762 VALUE_OFFSET (v
) = offset
+ VALUE_OFFSET (arg1
);
766 /* Given a value ARG1 of a struct or union type,
767 extract and return the value of one of its fields.
768 FIELDNO says which field.
770 For C++, must also be able to return values from static fields */
773 value_field (arg1
, fieldno
)
774 register value_ptr arg1
;
775 register int fieldno
;
777 return value_primitive_field (arg1
, 0, fieldno
, VALUE_TYPE (arg1
));
780 /* Return a non-virtual function as a value.
781 F is the list of member functions which contains the desired method.
782 J is an index into F which provides the desired method. */
785 value_fn_field (arg1p
, f
, j
, type
, offset
)
792 register value_ptr v
;
793 register struct type
*ftype
= TYPE_FN_FIELD_TYPE (f
, j
);
796 sym
= lookup_symbol (TYPE_FN_FIELD_PHYSNAME (f
, j
),
797 0, VAR_NAMESPACE
, 0, NULL
);
801 error ("Internal error: could not find physical method named %s",
802 TYPE_FN_FIELD_PHYSNAME (f, j));
805 v
= allocate_value (ftype
);
806 VALUE_ADDRESS (v
) = BLOCK_START (SYMBOL_BLOCK_VALUE (sym
));
807 VALUE_TYPE (v
) = ftype
;
811 if (type
!= VALUE_TYPE (*arg1p
))
812 *arg1p
= value_ind (value_cast (lookup_pointer_type (type
),
813 value_addr (*arg1p
)));
815 /* Move the `this' pointer according to the offset.
816 VALUE_OFFSET (*arg1p) += offset;
823 /* Return a virtual function as a value.
824 ARG1 is the object which provides the virtual function
825 table pointer. *ARG1P is side-effected in calling this function.
826 F is the list of member functions which contains the desired virtual
828 J is an index into F which provides the desired virtual function.
830 TYPE is the type in which F is located. */
832 value_virtual_fn_field (arg1p
, f
, j
, type
, offset
)
839 value_ptr arg1
= *arg1p
;
840 struct type
*type1
= check_typedef (VALUE_TYPE (arg1
));
841 struct type
*entry_type
;
842 /* First, get the virtual function table pointer. That comes
843 with a strange type, so cast it to type `pointer to long' (which
844 should serve just fine as a function type). Then, index into
845 the table, and convert final value to appropriate function type. */
846 value_ptr entry
, vfn
, vtbl
;
847 value_ptr vi
= value_from_longest (builtin_type_int
,
848 (LONGEST
) TYPE_FN_FIELD_VOFFSET (f
, j
));
849 struct type
*fcontext
= TYPE_FN_FIELD_FCONTEXT (f
, j
);
850 struct type
*context
;
851 if (fcontext
== NULL
)
852 /* We don't have an fcontext (e.g. the program was compiled with
853 g++ version 1). Try to get the vtbl from the TYPE_VPTR_BASETYPE.
854 This won't work right for multiple inheritance, but at least we
855 should do as well as GDB 3.x did. */
856 fcontext
= TYPE_VPTR_BASETYPE (type
);
857 context
= lookup_pointer_type (fcontext
);
858 /* Now context is a pointer to the basetype containing the vtbl. */
859 if (TYPE_TARGET_TYPE (context
) != type1
)
861 arg1
= value_ind (value_cast (context
, value_addr (arg1
)));
862 type1
= check_typedef (VALUE_TYPE (arg1
));
866 /* Now context is the basetype containing the vtbl. */
868 /* This type may have been defined before its virtual function table
869 was. If so, fill in the virtual function table entry for the
871 if (TYPE_VPTR_FIELDNO (context
) < 0)
872 fill_in_vptr_fieldno (context
);
874 /* The virtual function table is now an array of structures
875 which have the form { int16 offset, delta; void *pfn; }. */
876 vtbl
= value_ind (value_primitive_field (arg1
, 0,
877 TYPE_VPTR_FIELDNO (context
),
878 TYPE_VPTR_BASETYPE (context
)));
880 /* Index into the virtual function table. This is hard-coded because
881 looking up a field is not cheap, and it may be important to save
882 time, e.g. if the user has set a conditional breakpoint calling
883 a virtual function. */
884 entry
= value_subscript (vtbl
, vi
);
885 entry_type
= check_typedef (VALUE_TYPE (entry
));
887 if (TYPE_CODE (entry_type
) == TYPE_CODE_STRUCT
)
889 /* Move the `this' pointer according to the virtual function table. */
890 VALUE_OFFSET (arg1
) += value_as_long (value_field (entry
, 0));
892 if (! VALUE_LAZY (arg1
))
894 VALUE_LAZY (arg1
) = 1;
895 value_fetch_lazy (arg1
);
898 vfn
= value_field (entry
, 2);
900 else if (TYPE_CODE (entry_type
) == TYPE_CODE_PTR
)
903 error ("I'm confused: virtual function table has bad type");
904 /* Reinstantiate the function pointer with the correct type. */
905 VALUE_TYPE (vfn
) = lookup_pointer_type (TYPE_FN_FIELD_TYPE (f
, j
));
911 /* ARG is a pointer to an object we know to be at least
912 a DTYPE. BTYPE is the most derived basetype that has
913 already been searched (and need not be searched again).
914 After looking at the vtables between BTYPE and DTYPE,
915 return the most derived type we find. The caller must
916 be satisfied when the return value == DTYPE.
918 FIXME-tiemann: should work with dossier entries as well. */
921 value_headof (in_arg
, btype
, dtype
)
923 struct type
*btype
, *dtype
;
925 /* First collect the vtables we must look at for this object. */
926 /* FIXME-tiemann: right now, just look at top-most vtable. */
927 value_ptr arg
, vtbl
, entry
, best_entry
= 0;
929 int offset
, best_offset
= 0;
931 CORE_ADDR pc_for_sym
;
932 char *demangled_name
;
933 struct minimal_symbol
*msymbol
;
935 btype
= TYPE_VPTR_BASETYPE (dtype
);
936 CHECK_TYPEDEF (btype
);
939 arg
= value_cast (lookup_pointer_type (btype
), arg
);
940 vtbl
= value_ind (value_field (value_ind (arg
), TYPE_VPTR_FIELDNO (btype
)));
942 /* Check that VTBL looks like it points to a virtual function table. */
943 msymbol
= lookup_minimal_symbol_by_pc (VALUE_ADDRESS (vtbl
));
945 || (demangled_name
= SYMBOL_NAME (msymbol
)) == NULL
946 || !VTBL_PREFIX_P (demangled_name
))
948 /* If we expected to find a vtable, but did not, let the user
949 know that we aren't happy, but don't throw an error.
950 FIXME: there has to be a better way to do this. */
951 struct type
*error_type
= (struct type
*)xmalloc (sizeof (struct type
));
952 memcpy (error_type
, VALUE_TYPE (in_arg
), sizeof (struct type
));
953 TYPE_NAME (error_type
) = savestring ("suspicious *", sizeof ("suspicious *"));
954 VALUE_TYPE (in_arg
) = error_type
;
958 /* Now search through the virtual function table. */
959 entry
= value_ind (vtbl
);
960 nelems
= longest_to_int (value_as_long (value_field (entry
, 2)));
961 for (i
= 1; i
<= nelems
; i
++)
963 entry
= value_subscript (vtbl
, value_from_longest (builtin_type_int
,
965 /* This won't work if we're using thunks. */
966 if (TYPE_CODE (check_typedef (VALUE_TYPE (entry
))) != TYPE_CODE_STRUCT
)
968 offset
= longest_to_int (value_as_long (value_field (entry
, 0)));
969 /* If we use '<=' we can handle single inheritance
970 * where all offsets are zero - just use the first entry found. */
971 if (offset
<= best_offset
)
973 best_offset
= offset
;
977 /* Move the pointer according to BEST_ENTRY's offset, and figure
978 out what type we should return as the new pointer. */
981 /* An alternative method (which should no longer be necessary).
982 * But we leave it in for future use, when we will hopefully
983 * have optimizes the vtable to use thunks instead of offsets. */
984 /* Use the name of vtable itself to extract a base type. */
985 demangled_name
+= 4; /* Skip _vt$ prefix. */
989 pc_for_sym
= value_as_pointer (value_field (best_entry
, 2));
990 sym
= find_pc_function (pc_for_sym
);
991 demangled_name
= cplus_demangle (SYMBOL_NAME (sym
), DMGL_ANSI
);
992 *(strchr (demangled_name
, ':')) = '\0';
994 sym
= lookup_symbol (demangled_name
, 0, VAR_NAMESPACE
, 0, 0);
996 error ("could not find type declaration for `%s'", demangled_name
);
999 free (demangled_name
);
1000 arg
= value_add (value_cast (builtin_type_int
, arg
),
1001 value_field (best_entry
, 0));
1004 VALUE_TYPE (arg
) = lookup_pointer_type (SYMBOL_TYPE (sym
));
1008 /* ARG is a pointer object of type TYPE. If TYPE has virtual
1009 function tables, probe ARG's tables (including the vtables
1010 of its baseclasses) to figure out the most derived type that ARG
1011 could actually be a pointer to. */
1014 value_from_vtable_info (arg
, type
)
1018 /* Take care of preliminaries. */
1019 if (TYPE_VPTR_FIELDNO (type
) < 0)
1020 fill_in_vptr_fieldno (type
);
1021 if (TYPE_VPTR_FIELDNO (type
) < 0)
1024 return value_headof (arg
, 0, type
);
1027 /* Return true if the INDEXth field of TYPE is a virtual baseclass
1028 pointer which is for the base class whose type is BASECLASS. */
1031 vb_match (type
, index
, basetype
)
1034 struct type
*basetype
;
1036 struct type
*fieldtype
;
1037 char *name
= TYPE_FIELD_NAME (type
, index
);
1038 char *field_class_name
= NULL
;
1042 /* gcc 2.4 uses _vb$. */
1043 if (name
[1] == 'v' && name
[2] == 'b' && name
[3] == CPLUS_MARKER
)
1044 field_class_name
= name
+ 4;
1045 /* gcc 2.5 will use __vb_. */
1046 if (name
[1] == '_' && name
[2] == 'v' && name
[3] == 'b' && name
[4] == '_')
1047 field_class_name
= name
+ 5;
1049 if (field_class_name
== NULL
)
1050 /* This field is not a virtual base class pointer. */
1053 /* It's a virtual baseclass pointer, now we just need to find out whether
1054 it is for this baseclass. */
1055 fieldtype
= TYPE_FIELD_TYPE (type
, index
);
1056 if (fieldtype
== NULL
1057 || TYPE_CODE (fieldtype
) != TYPE_CODE_PTR
)
1058 /* "Can't happen". */
1061 /* What we check for is that either the types are equal (needed for
1062 nameless types) or have the same name. This is ugly, and a more
1063 elegant solution should be devised (which would probably just push
1064 the ugliness into symbol reading unless we change the stabs format). */
1065 if (TYPE_TARGET_TYPE (fieldtype
) == basetype
)
1068 if (TYPE_NAME (basetype
) != NULL
1069 && TYPE_NAME (TYPE_TARGET_TYPE (fieldtype
)) != NULL
1070 && STREQ (TYPE_NAME (basetype
),
1071 TYPE_NAME (TYPE_TARGET_TYPE (fieldtype
))))
1076 /* Compute the offset of the baseclass which is
1077 the INDEXth baseclass of class TYPE,
1078 for value at VALADDR (in host) at ADDRESS (in target).
1079 The result is the offset of the baseclass value relative
1080 to (the address of)(ARG) + OFFSET.
1082 -1 is returned on error. */
1085 baseclass_offset (type
, index
, valaddr
, address
)
1091 struct type
*basetype
= TYPE_BASECLASS (type
, index
);
1093 if (BASETYPE_VIA_VIRTUAL (type
, index
))
1095 /* Must hunt for the pointer to this virtual baseclass. */
1096 register int i
, len
= TYPE_NFIELDS (type
);
1097 register int n_baseclasses
= TYPE_N_BASECLASSES (type
);
1099 /* First look for the virtual baseclass pointer
1101 for (i
= n_baseclasses
; i
< len
; i
++)
1103 if (vb_match (type
, i
, basetype
))
1106 = unpack_pointer (TYPE_FIELD_TYPE (type
, i
),
1107 valaddr
+ (TYPE_FIELD_BITPOS (type
, i
) / 8));
1109 return addr
- (LONGEST
) address
;
1112 /* Not in the fields, so try looking through the baseclasses. */
1113 for (i
= index
+1; i
< n_baseclasses
; i
++)
1116 baseclass_offset (type
, i
, valaddr
, address
);
1124 /* Baseclass is easily computed. */
1125 return TYPE_BASECLASS_BITPOS (type
, index
) / 8;
1128 /* Unpack a field FIELDNO of the specified TYPE, from the anonymous object at
1131 Extracting bits depends on endianness of the machine. Compute the
1132 number of least significant bits to discard. For big endian machines,
1133 we compute the total number of bits in the anonymous object, subtract
1134 off the bit count from the MSB of the object to the MSB of the
1135 bitfield, then the size of the bitfield, which leaves the LSB discard
1136 count. For little endian machines, the discard count is simply the
1137 number of bits from the LSB of the anonymous object to the LSB of the
1140 If the field is signed, we also do sign extension. */
1143 unpack_field_as_long (type
, valaddr
, fieldno
)
1148 unsigned LONGEST val
;
1149 unsigned LONGEST valmask
;
1150 int bitpos
= TYPE_FIELD_BITPOS (type
, fieldno
);
1151 int bitsize
= TYPE_FIELD_BITSIZE (type
, fieldno
);
1154 val
= extract_unsigned_integer (valaddr
+ bitpos
/ 8, sizeof (val
));
1156 /* Extract bits. See comment above. */
1158 if (BITS_BIG_ENDIAN
)
1159 lsbcount
= (sizeof val
* 8 - bitpos
% 8 - bitsize
);
1161 lsbcount
= (bitpos
% 8);
1164 /* If the field does not entirely fill a LONGEST, then zero the sign bits.
1165 If the field is signed, and is negative, then sign extend. */
1167 if ((bitsize
> 0) && (bitsize
< 8 * sizeof (val
)))
1169 valmask
= (((unsigned LONGEST
) 1) << bitsize
) - 1;
1171 if (!TYPE_UNSIGNED (TYPE_FIELD_TYPE (type
, fieldno
)))
1173 if (val
& (valmask
^ (valmask
>> 1)))
1182 /* Modify the value of a bitfield. ADDR points to a block of memory in
1183 target byte order; the bitfield starts in the byte pointed to. FIELDVAL
1184 is the desired value of the field, in host byte order. BITPOS and BITSIZE
1185 indicate which bits (in target bit order) comprise the bitfield. */
1188 modify_field (addr
, fieldval
, bitpos
, bitsize
)
1191 int bitpos
, bitsize
;
1195 /* If a negative fieldval fits in the field in question, chop
1196 off the sign extension bits. */
1197 if (bitsize
< (8 * sizeof (fieldval
))
1198 && (~fieldval
& ~((1 << (bitsize
- 1)) - 1)) == 0)
1199 fieldval
= fieldval
& ((1 << bitsize
) - 1);
1201 /* Warn if value is too big to fit in the field in question. */
1202 if (bitsize
< (8 * sizeof (fieldval
))
1203 && 0 != (fieldval
& ~((1<<bitsize
)-1)))
1205 /* FIXME: would like to include fieldval in the message, but
1206 we don't have a sprintf_longest. */
1207 warning ("Value does not fit in %d bits.", bitsize
);
1209 /* Truncate it, otherwise adjoining fields may be corrupted. */
1210 fieldval
= fieldval
& ((1 << bitsize
) - 1);
1213 oword
= extract_signed_integer (addr
, sizeof oword
);
1215 /* Shifting for bit field depends on endianness of the target machine. */
1216 if (BITS_BIG_ENDIAN
)
1217 bitpos
= sizeof (oword
) * 8 - bitpos
- bitsize
;
1219 /* Mask out old value, while avoiding shifts >= size of oword */
1220 if (bitsize
< 8 * sizeof (oword
))
1221 oword
&= ~(((((unsigned LONGEST
)1) << bitsize
) - 1) << bitpos
);
1223 oword
&= ~((~(unsigned LONGEST
)0) << bitpos
);
1224 oword
|= fieldval
<< bitpos
;
1226 store_signed_integer (addr
, sizeof oword
, oword
);
1229 /* Convert C numbers into newly allocated values */
1232 value_from_longest (type
, num
)
1234 register LONGEST num
;
1236 register value_ptr val
= allocate_value (type
);
1237 register enum type_code code
;
1240 code
= TYPE_CODE (type
);
1241 len
= TYPE_LENGTH (type
);
1245 case TYPE_CODE_TYPEDEF
:
1246 type
= check_typedef (type
);
1249 case TYPE_CODE_CHAR
:
1250 case TYPE_CODE_ENUM
:
1251 case TYPE_CODE_BOOL
:
1252 case TYPE_CODE_RANGE
:
1253 store_signed_integer (VALUE_CONTENTS_RAW (val
), len
, num
);
1258 /* This assumes that all pointers of a given length
1259 have the same form. */
1260 store_address (VALUE_CONTENTS_RAW (val
), len
, (CORE_ADDR
) num
);
1264 error ("Unexpected type encountered for integer constant.");
1270 value_from_double (type
, num
)
1274 register value_ptr val
= allocate_value (type
);
1275 struct type
*base_type
= check_typedef (type
);
1276 register enum type_code code
= TYPE_CODE (base_type
);
1277 register int len
= TYPE_LENGTH (base_type
);
1279 if (code
== TYPE_CODE_FLT
)
1281 store_floating (VALUE_CONTENTS_RAW (val
), len
, num
);
1284 error ("Unexpected type encountered for floating constant.");
1289 /* Deal with the value that is "about to be returned". */
1291 /* Return the value that a function returning now
1292 would be returning to its caller, assuming its type is VALTYPE.
1293 RETBUF is where we look for what ought to be the contents
1294 of the registers (in raw form). This is because it is often
1295 desirable to restore old values to those registers
1296 after saving the contents of interest, and then call
1297 this function using the saved values.
1298 struct_return is non-zero when the function in question is
1299 using the structure return conventions on the machine in question;
1300 0 when it is using the value returning conventions (this often
1301 means returning pointer to where structure is vs. returning value). */
1304 value_being_returned (valtype
, retbuf
, struct_return
)
1305 register struct type
*valtype
;
1306 char retbuf
[REGISTER_BYTES
];
1310 register value_ptr val
;
1313 #if defined (EXTRACT_STRUCT_VALUE_ADDRESS)
1314 /* If this is not defined, just use EXTRACT_RETURN_VALUE instead. */
1315 if (struct_return
) {
1316 addr
= EXTRACT_STRUCT_VALUE_ADDRESS (retbuf
);
1318 error ("Function return value unknown");
1319 return value_at (valtype
, addr
);
1323 val
= allocate_value (valtype
);
1324 CHECK_TYPEDEF (valtype
);
1325 EXTRACT_RETURN_VALUE (valtype
, retbuf
, VALUE_CONTENTS_RAW (val
));
1330 /* Should we use EXTRACT_STRUCT_VALUE_ADDRESS instead of
1331 EXTRACT_RETURN_VALUE? GCC_P is true if compiled with gcc
1332 and TYPE is the type (which is known to be struct, union or array).
1334 On most machines, the struct convention is used unless we are
1335 using gcc and the type is of a special size. */
1336 /* As of about 31 Mar 93, GCC was changed to be compatible with the
1337 native compiler. GCC 2.3.3 was the last release that did it the
1338 old way. Since gcc2_compiled was not changed, we have no
1339 way to correctly win in all cases, so we just do the right thing
1340 for gcc1 and for gcc2 after this change. Thus it loses for gcc
1341 2.0-2.3.3. This is somewhat unfortunate, but changing gcc2_compiled
1342 would cause more chaos than dealing with some struct returns being
1344 #if !defined (USE_STRUCT_CONVENTION)
1345 #define USE_STRUCT_CONVENTION(gcc_p, type)\
1346 (!((gcc_p == 1) && (TYPE_LENGTH (value_type) == 1 \
1347 || TYPE_LENGTH (value_type) == 2 \
1348 || TYPE_LENGTH (value_type) == 4 \
1349 || TYPE_LENGTH (value_type) == 8 \
1354 /* Return true if the function specified is using the structure returning
1355 convention on this machine to return arguments, or 0 if it is using
1356 the value returning convention. FUNCTION is the value representing
1357 the function, FUNCADDR is the address of the function, and VALUE_TYPE
1358 is the type returned by the function. GCC_P is nonzero if compiled
1362 using_struct_return (function
, funcaddr
, value_type
, gcc_p
)
1365 struct type
*value_type
;
1369 register enum type_code code
= TYPE_CODE (value_type
);
1371 if (code
== TYPE_CODE_ERROR
)
1372 error ("Function return type unknown.");
1374 if (code
== TYPE_CODE_STRUCT
||
1375 code
== TYPE_CODE_UNION
||
1376 code
== TYPE_CODE_ARRAY
)
1377 return USE_STRUCT_CONVENTION (gcc_p
, value_type
);
1382 /* Store VAL so it will be returned if a function returns now.
1383 Does not verify that VAL's type matches what the current
1384 function wants to return. */
1387 set_return_value (val
)
1390 struct type
*type
= check_typedef (VALUE_TYPE (val
));
1391 register enum type_code code
= TYPE_CODE (type
);
1393 if (code
== TYPE_CODE_ERROR
)
1394 error ("Function return type unknown.");
1396 if ( code
== TYPE_CODE_STRUCT
1397 || code
== TYPE_CODE_UNION
) /* FIXME, implement struct return. */
1398 error ("GDB does not support specifying a struct or union return value.");
1400 STORE_RETURN_VALUE (type
, VALUE_CONTENTS (val
));
1404 _initialize_values ()
1406 add_cmd ("convenience", no_class
, show_convenience
,
1407 "Debugger convenience (\"$foo\") variables.\n\
1408 These variables are created when you assign them values;\n\
1409 thus, \"print $foo=1\" gives \"$foo\" the value 1. Values may be any type.\n\n\
1410 A few convenience variables are given values automatically:\n\
1411 \"$_\"holds the last address examined with \"x\" or \"info lines\",\n\
1412 \"$__\" holds the contents of the last address examined with \"x\".",
1415 add_cmd ("values", no_class
, show_values
,
1416 "Elements of value history around item number IDX (or last ten).",