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);
620 return extract_unsigned_integer (valaddr, len);
622 return extract_signed_integer (valaddr, len);
625 return extract_floating (valaddr, len);
629 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
630 whether we want this to be true eventually. */
631 return extract_address (valaddr, len);
633 case TYPE_CODE_MEMBER:
634 error ("not implemented: member types in unpack_long");
637 error ("Value can't be converted to integer.");
639 return 0; /* Placate lint. */
642 /* Return a double value from the specified type and address.
643 INVP points to an int which is set to 0 for valid value,
644 1 for invalid value (bad float format). In either case,
645 the returned double is OK to use. Argument is in target
646 format, result is in host format. */
649 unpack_double (type, valaddr, invp)
654 register enum type_code code = TYPE_CODE (type);
655 register int len = TYPE_LENGTH (type);
656 register int nosign = TYPE_UNSIGNED (type);
658 *invp = 0; /* Assume valid. */
659 if (code == TYPE_CODE_FLT)
661 if (INVALID_FLOAT (valaddr, len))
664 return 1.234567891011121314;
666 return extract_floating (valaddr, len);
670 /* Unsigned -- be sure we compensate for signed LONGEST. */
671 return (unsigned LONGEST) unpack_long (type, valaddr);
675 /* Signed -- we are OK with unpack_long. */
676 return unpack_long (type, valaddr);
680 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
681 as a CORE_ADDR, assuming the raw data is described by type TYPE.
682 We don't assume any alignment for the raw data. Return value is in
685 If you want functions and arrays to be coerced to pointers, and
686 references to be dereferenced, call value_as_pointer() instead.
688 C++: It is assumed that the front-end has taken care of
689 all matters concerning pointers to members. A pointer
690 to member which reaches here is considered to be equivalent
691 to an INT (or some size). After all, it is only an offset. */
694 unpack_pointer (type, valaddr)
698 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
699 whether we want this to be true eventually. */
700 return unpack_long (type, valaddr);
703 /* Given a value ARG1 (offset by OFFSET bytes)
704 of a struct or union type ARG_TYPE,
705 extract and return the value of one of its fields.
706 FIELDNO says which field.
708 For C++, must also be able to return values from static fields */
711 value_primitive_field (arg1, offset, fieldno, arg_type)
712 register value_ptr arg1;
714 register int fieldno;
715 register struct type *arg_type;
717 register value_ptr v;
718 register struct type *type;
720 check_stub_type (arg_type);
721 type = TYPE_FIELD_TYPE (arg_type, fieldno);
723 /* Handle packed fields */
725 offset += TYPE_FIELD_BITPOS (arg_type, fieldno) / 8;
726 if (TYPE_FIELD_BITSIZE (arg_type, fieldno))
728 v = value_from_longest (type,
729 unpack_field_as_long (arg_type,
730 VALUE_CONTENTS (arg1),
732 VALUE_BITPOS (v) = TYPE_FIELD_BITPOS (arg_type, fieldno) % 8;
733 VALUE_BITSIZE (v) = TYPE_FIELD_BITSIZE (arg_type, fieldno);
737 v = allocate_value (type);
738 if (VALUE_LAZY (arg1))
741 memcpy (VALUE_CONTENTS_RAW (v), VALUE_CONTENTS_RAW (arg1) + offset,
744 VALUE_LVAL (v) = VALUE_LVAL (arg1);
745 if (VALUE_LVAL (arg1) == lval_internalvar)
746 VALUE_LVAL (v) = lval_internalvar_component;
747 VALUE_ADDRESS (v) = VALUE_ADDRESS (arg1);
748 VALUE_OFFSET (v) = offset + VALUE_OFFSET (arg1);
752 /* Given a value ARG1 of a struct or union type,
753 extract and return the value of one of its fields.
754 FIELDNO says which field.
756 For C++, must also be able to return values from static fields */
759 value_field (arg1, fieldno)
760 register value_ptr arg1;
761 register int fieldno;
763 return value_primitive_field (arg1, 0, fieldno, VALUE_TYPE (arg1));
766 /* Return a non-virtual function as a value.
767 F is the list of member functions which contains the desired method.
768 J is an index into F which provides the desired method. */
771 value_fn_field (arg1p, f, j, type, offset)
778 register value_ptr v;
779 register struct type *ftype = TYPE_FN_FIELD_TYPE (f, j);
782 sym = lookup_symbol (TYPE_FN_FIELD_PHYSNAME (f, j),
783 0, VAR_NAMESPACE, 0, NULL);
787 error ("Internal error: could not find physical method named %s",
788 TYPE_FN_FIELD_PHYSNAME (f, j));
791 v = allocate_value (ftype);
792 VALUE_ADDRESS (v) = BLOCK_START (SYMBOL_BLOCK_VALUE (sym));
793 VALUE_TYPE (v) = ftype;
797 if (type != VALUE_TYPE (*arg1p))
798 *arg1p = value_ind (value_cast (lookup_pointer_type (type),
799 value_addr (*arg1p)));
801 /* Move the `this' pointer according to the offset.
802 VALUE_OFFSET (*arg1p) += offset;
809 /* Return a virtual function as a value.
810 ARG1 is the object which provides the virtual function
811 table pointer. *ARG1P is side-effected in calling this function.
812 F is the list of member functions which contains the desired virtual
814 J is an index into F which provides the desired virtual function.
816 TYPE is the type in which F is located. */
818 value_virtual_fn_field (arg1p, f, j, type, offset)
825 value_ptr arg1 = *arg1p;
826 /* First, get the virtual function table pointer. That comes
827 with a strange type, so cast it to type `pointer to long' (which
828 should serve just fine as a function type). Then, index into
829 the table, and convert final value to appropriate function type. */
830 value_ptr entry, vfn, vtbl;
831 value_ptr vi = value_from_longest (builtin_type_int,
832 (LONGEST) TYPE_FN_FIELD_VOFFSET (f, j));
833 struct type *fcontext = TYPE_FN_FIELD_FCONTEXT (f, j);
834 struct type *context;
835 if (fcontext == NULL)
836 /* We don't have an fcontext (e.g. the program was compiled with
837 g++ version 1). Try to get the vtbl from the TYPE_VPTR_BASETYPE.
838 This won't work right for multiple inheritance, but at least we
839 should do as well as GDB 3.x did. */
840 fcontext = TYPE_VPTR_BASETYPE (type);
841 context = lookup_pointer_type (fcontext);
842 /* Now context is a pointer to the basetype containing the vtbl. */
843 if (TYPE_TARGET_TYPE (context) != VALUE_TYPE (arg1))
844 arg1 = value_ind (value_cast (context, value_addr (arg1)));
846 context = VALUE_TYPE (arg1);
847 /* Now context is the basetype containing the vtbl. */
849 /* This type may have been defined before its virtual function table
850 was. If so, fill in the virtual function table entry for the
852 if (TYPE_VPTR_FIELDNO (context) < 0)
853 fill_in_vptr_fieldno (context);
855 /* The virtual function table is now an array of structures
856 which have the form { int16 offset, delta; void *pfn; }. */
857 vtbl = value_ind (value_primitive_field (arg1, 0,
858 TYPE_VPTR_FIELDNO (context),
859 TYPE_VPTR_BASETYPE (context)));
861 /* Index into the virtual function table. This is hard-coded because
862 looking up a field is not cheap, and it may be important to save
863 time, e.g. if the user has set a conditional breakpoint calling
864 a virtual function. */
865 entry = value_subscript (vtbl, vi);
867 /* Move the `this' pointer according to the virtual function table. */
868 VALUE_OFFSET (arg1) += value_as_long (value_field (entry, 0))/* + offset*/;
870 if (! VALUE_LAZY (arg1))
872 VALUE_LAZY (arg1) = 1;
873 value_fetch_lazy (arg1);
876 vfn = value_field (entry, 2);
877 /* Reinstantiate the function pointer with the correct type. */
878 VALUE_TYPE (vfn) = lookup_pointer_type (TYPE_FN_FIELD_TYPE (f, j));
884 /* ARG is a pointer to an object we know to be at least
885 a DTYPE. BTYPE is the most derived basetype that has
886 already been searched (and need not be searched again).
887 After looking at the vtables between BTYPE and DTYPE,
888 return the most derived type we find. The caller must
889 be satisfied when the return value == DTYPE.
891 FIXME-tiemann: should work with dossier entries as well. */
894 value_headof (in_arg, btype, dtype)
896 struct type *btype, *dtype;
898 /* First collect the vtables we must look at for this object. */
899 /* FIXME-tiemann: right now, just look at top-most vtable. */
900 value_ptr arg, vtbl, entry, best_entry = 0;
902 int offset, best_offset = 0;
904 CORE_ADDR pc_for_sym;
905 char *demangled_name;
906 struct minimal_symbol *msymbol;
908 btype = TYPE_VPTR_BASETYPE (dtype);
909 check_stub_type (btype);
912 arg = value_cast (lookup_pointer_type (btype), arg);
913 vtbl = value_ind (value_field (value_ind (arg), TYPE_VPTR_FIELDNO (btype)));
915 /* Check that VTBL looks like it points to a virtual function table. */
916 msymbol = lookup_minimal_symbol_by_pc (VALUE_ADDRESS (vtbl));
918 || !VTBL_PREFIX_P (demangled_name = SYMBOL_NAME (msymbol)))
920 /* If we expected to find a vtable, but did not, let the user
921 know that we aren't happy, but don't throw an error.
922 FIXME: there has to be a better way to do this. */
923 struct type *error_type = (struct type *)xmalloc (sizeof (struct type));
924 memcpy (error_type, VALUE_TYPE (in_arg), sizeof (struct type));
925 TYPE_NAME (error_type) = savestring ("suspicious *", sizeof ("suspicious *"));
926 VALUE_TYPE (in_arg) = error_type;
930 /* Now search through the virtual function table. */
931 entry = value_ind (vtbl);
932 nelems = longest_to_int (value_as_long (value_field (entry, 2)));
933 for (i = 1; i <= nelems; i++)
935 entry = value_subscript (vtbl, value_from_longest (builtin_type_int,
937 offset = longest_to_int (value_as_long (value_field (entry, 0)));
938 /* If we use '<=' we can handle single inheritance
939 * where all offsets are zero - just use the first entry found. */
940 if (offset <= best_offset)
942 best_offset = offset;
946 /* Move the pointer according to BEST_ENTRY's offset, and figure
947 out what type we should return as the new pointer. */
950 /* An alternative method (which should no longer be necessary).
951 * But we leave it in for future use, when we will hopefully
952 * have optimizes the vtable to use thunks instead of offsets. */
953 /* Use the name of vtable itself to extract a base type. */
954 demangled_name += 4; /* Skip _vt$ prefix. */
958 pc_for_sym = value_as_pointer (value_field (best_entry, 2));
959 sym = find_pc_function (pc_for_sym);
960 demangled_name = cplus_demangle (SYMBOL_NAME (sym), DMGL_ANSI);
961 *(strchr (demangled_name, ':')) = '\0';
963 sym = lookup_symbol (demangled_name, 0, VAR_NAMESPACE, 0, 0);
965 error ("could not find type declaration for `%s'", demangled_name);
968 free (demangled_name);
969 arg = value_add (value_cast (builtin_type_int, arg),
970 value_field (best_entry, 0));
973 VALUE_TYPE (arg) = lookup_pointer_type (SYMBOL_TYPE (sym));
977 /* ARG is a pointer object of type TYPE. If TYPE has virtual
978 function tables, probe ARG's tables (including the vtables
979 of its baseclasses) to figure out the most derived type that ARG
980 could actually be a pointer to. */
983 value_from_vtable_info (arg, type)
987 /* Take care of preliminaries. */
988 if (TYPE_VPTR_FIELDNO (type) < 0)
989 fill_in_vptr_fieldno (type);
990 if (TYPE_VPTR_FIELDNO (type) < 0 || VALUE_REPEATED (arg))
993 return value_headof (arg, 0, type);
996 /* Return true if the INDEXth field of TYPE is a virtual baseclass
997 pointer which is for the base class whose type is BASECLASS. */
1000 vb_match (type, index, basetype)
1003 struct type *basetype;
1005 struct type *fieldtype;
1006 char *name = TYPE_FIELD_NAME (type, index);
1007 char *field_class_name = NULL;
1011 /* gcc 2.4 uses _vb$. */
1012 if (name[1] == 'v' && name[2] == 'b' && name[3] == CPLUS_MARKER)
1013 field_class_name = name + 4;
1014 /* gcc 2.5 will use __vb_. */
1015 if (name[1] == '_' && name[2] == 'v' && name[3] == 'b' && name[4] == '_')
1016 field_class_name = name + 5;
1018 if (field_class_name == NULL)
1019 /* This field is not a virtual base class pointer. */
1022 /* It's a virtual baseclass pointer, now we just need to find out whether
1023 it is for this baseclass. */
1024 fieldtype = TYPE_FIELD_TYPE (type, index);
1025 if (fieldtype == NULL
1026 || TYPE_CODE (fieldtype) != TYPE_CODE_PTR)
1027 /* "Can't happen". */
1030 /* What we check for is that either the types are equal (needed for
1031 nameless types) or have the same name. This is ugly, and a more
1032 elegant solution should be devised (which would probably just push
1033 the ugliness into symbol reading unless we change the stabs format). */
1034 if (TYPE_TARGET_TYPE (fieldtype) == basetype)
1037 if (TYPE_NAME (basetype) != NULL
1038 && TYPE_NAME (TYPE_TARGET_TYPE (fieldtype)) != NULL
1039 && STREQ (TYPE_NAME (basetype),
1040 TYPE_NAME (TYPE_TARGET_TYPE (fieldtype))))
1045 /* Compute the offset of the baseclass which is
1046 the INDEXth baseclass of class TYPE, for a value ARG,
1047 wih extra offset of OFFSET.
1048 The result is the offste of the baseclass value relative
1049 to (the address of)(ARG) + OFFSET.
1051 -1 is returned on error. */
1054 baseclass_offset (type, index, arg, offset)
1060 struct type *basetype = TYPE_BASECLASS (type, index);
1062 if (BASETYPE_VIA_VIRTUAL (type, index))
1064 /* Must hunt for the pointer to this virtual baseclass. */
1065 register int i, len = TYPE_NFIELDS (type);
1066 register int n_baseclasses = TYPE_N_BASECLASSES (type);
1068 /* First look for the virtual baseclass pointer
1070 for (i = n_baseclasses; i < len; i++)
1072 if (vb_match (type, i, basetype))
1075 = unpack_pointer (TYPE_FIELD_TYPE (type, i),
1076 VALUE_CONTENTS (arg) + VALUE_OFFSET (arg)
1078 + (TYPE_FIELD_BITPOS (type, i) / 8));
1080 if (VALUE_LVAL (arg) != lval_memory)
1084 (LONGEST) (VALUE_ADDRESS (arg) + VALUE_OFFSET (arg) + offset);
1087 /* Not in the fields, so try looking through the baseclasses. */
1088 for (i = index+1; i < n_baseclasses; i++)
1091 baseclass_offset (type, i, arg, offset);
1099 /* Baseclass is easily computed. */
1100 return TYPE_BASECLASS_BITPOS (type, index) / 8;
1103 /* Compute the address of the baseclass which is
1104 the INDEXth baseclass of class TYPE. The TYPE base
1105 of the object is at VALADDR.
1107 If ERRP is non-NULL, set *ERRP to be the errno code of any error,
1108 or 0 if no error. In that case the return value is not the address
1109 of the baseclasss, but the address which could not be read
1112 /* FIXME Fix remaining uses of baseclass_addr to use baseclass_offset */
1115 baseclass_addr (type, index, valaddr, valuep, errp)
1122 struct type *basetype = TYPE_BASECLASS (type, index);
1127 if (BASETYPE_VIA_VIRTUAL (type, index))
1129 /* Must hunt for the pointer to this virtual baseclass. */
1130 register int i, len = TYPE_NFIELDS (type);
1131 register int n_baseclasses = TYPE_N_BASECLASSES (type);
1133 /* First look for the virtual baseclass pointer
1135 for (i = n_baseclasses; i < len; i++)
1137 if (vb_match (type, i, basetype))
1139 value_ptr val = allocate_value (basetype);
1144 = unpack_pointer (TYPE_FIELD_TYPE (type, i),
1145 valaddr + (TYPE_FIELD_BITPOS (type, i) / 8));
1147 status = target_read_memory (addr,
1148 VALUE_CONTENTS_RAW (val),
1149 TYPE_LENGTH (basetype));
1150 VALUE_LVAL (val) = lval_memory;
1151 VALUE_ADDRESS (val) = addr;
1157 release_value (val);
1161 return (char *)addr;
1167 return (char *) VALUE_CONTENTS (val);
1171 /* Not in the fields, so try looking through the baseclasses. */
1172 for (i = index+1; i < n_baseclasses; i++)
1176 baddr = baseclass_addr (type, i, valaddr, valuep, errp);
1186 /* Baseclass is easily computed. */
1189 return valaddr + TYPE_BASECLASS_BITPOS (type, index) / 8;
1192 /* Unpack a field FIELDNO of the specified TYPE, from the anonymous object at
1195 Extracting bits depends on endianness of the machine. Compute the
1196 number of least significant bits to discard. For big endian machines,
1197 we compute the total number of bits in the anonymous object, subtract
1198 off the bit count from the MSB of the object to the MSB of the
1199 bitfield, then the size of the bitfield, which leaves the LSB discard
1200 count. For little endian machines, the discard count is simply the
1201 number of bits from the LSB of the anonymous object to the LSB of the
1204 If the field is signed, we also do sign extension. */
1207 unpack_field_as_long (type, valaddr, fieldno)
1212 unsigned LONGEST val;
1213 unsigned LONGEST valmask;
1214 int bitpos = TYPE_FIELD_BITPOS (type, fieldno);
1215 int bitsize = TYPE_FIELD_BITSIZE (type, fieldno);
1218 val = extract_unsigned_integer (valaddr + bitpos / 8, sizeof (val));
1220 /* Extract bits. See comment above. */
1223 lsbcount = (sizeof val * 8 - bitpos % 8 - bitsize);
1225 lsbcount = (bitpos % 8);
1229 /* If the field does not entirely fill a LONGEST, then zero the sign bits.
1230 If the field is signed, and is negative, then sign extend. */
1232 if ((bitsize > 0) && (bitsize < 8 * sizeof (val)))
1234 valmask = (((unsigned LONGEST) 1) << bitsize) - 1;
1236 if (!TYPE_UNSIGNED (TYPE_FIELD_TYPE (type, fieldno)))
1238 if (val & (valmask ^ (valmask >> 1)))
1247 /* Modify the value of a bitfield. ADDR points to a block of memory in
1248 target byte order; the bitfield starts in the byte pointed to. FIELDVAL
1249 is the desired value of the field, in host byte order. BITPOS and BITSIZE
1250 indicate which bits (in target bit order) comprise the bitfield. */
1253 modify_field (addr, fieldval, bitpos, bitsize)
1256 int bitpos, bitsize;
1260 /* Reject values too big to fit in the field in question,
1261 otherwise adjoining fields may be corrupted. */
1262 if (bitsize < (8 * sizeof (fieldval))
1263 && 0 != (fieldval & ~((1<<bitsize)-1)))
1265 /* FIXME: would like to include fieldval in the message, but
1266 we don't have a sprintf_longest. */
1267 error ("Value does not fit in %d bits.", bitsize);
1270 oword = extract_signed_integer (addr, sizeof oword);
1272 /* Shifting for bit field depends on endianness of the target machine. */
1274 bitpos = sizeof (oword) * 8 - bitpos - bitsize;
1277 /* Mask out old value, while avoiding shifts >= size of oword */
1278 if (bitsize < 8 * sizeof (oword))
1279 oword &= ~(((((unsigned LONGEST)1) << bitsize) - 1) << bitpos);
1281 oword &= ~((~(unsigned LONGEST)0) << bitpos);
1282 oword |= fieldval << bitpos;
1284 store_signed_integer (addr, sizeof oword, oword);
1287 /* Convert C numbers into newly allocated values */
1290 value_from_longest (type, num)
1292 register LONGEST num;
1294 register value_ptr val = allocate_value (type);
1295 register enum type_code code = TYPE_CODE (type);
1296 register int len = TYPE_LENGTH (type);
1301 case TYPE_CODE_CHAR:
1302 case TYPE_CODE_ENUM:
1303 case TYPE_CODE_BOOL:
1304 store_signed_integer (VALUE_CONTENTS_RAW (val), len, num);
1309 /* This assumes that all pointers of a given length
1310 have the same form. */
1311 store_address (VALUE_CONTENTS_RAW (val), len, (CORE_ADDR) num);
1315 error ("Unexpected type encountered for integer constant.");
1321 value_from_double (type, num)
1325 register value_ptr val = allocate_value (type);
1326 register enum type_code code = TYPE_CODE (type);
1327 register int len = TYPE_LENGTH (type);
1329 if (code == TYPE_CODE_FLT)
1331 store_floating (VALUE_CONTENTS_RAW (val), len, num);
1334 error ("Unexpected type encountered for floating constant.");
1339 /* Deal with the value that is "about to be returned". */
1341 /* Return the value that a function returning now
1342 would be returning to its caller, assuming its type is VALTYPE.
1343 RETBUF is where we look for what ought to be the contents
1344 of the registers (in raw form). This is because it is often
1345 desirable to restore old values to those registers
1346 after saving the contents of interest, and then call
1347 this function using the saved values.
1348 struct_return is non-zero when the function in question is
1349 using the structure return conventions on the machine in question;
1350 0 when it is using the value returning conventions (this often
1351 means returning pointer to where structure is vs. returning value). */
1354 value_being_returned (valtype, retbuf, struct_return)
1355 register struct type *valtype;
1356 char retbuf[REGISTER_BYTES];
1360 register value_ptr val;
1363 #if defined (EXTRACT_STRUCT_VALUE_ADDRESS)
1364 /* If this is not defined, just use EXTRACT_RETURN_VALUE instead. */
1365 if (struct_return) {
1366 addr = EXTRACT_STRUCT_VALUE_ADDRESS (retbuf);
1368 error ("Function return value unknown");
1369 return value_at (valtype, addr);
1373 val = allocate_value (valtype);
1374 EXTRACT_RETURN_VALUE (valtype, retbuf, VALUE_CONTENTS_RAW (val));
1379 /* Should we use EXTRACT_STRUCT_VALUE_ADDRESS instead of
1380 EXTRACT_RETURN_VALUE? GCC_P is true if compiled with gcc
1381 and TYPE is the type (which is known to be struct, union or array).
1383 On most machines, the struct convention is used unless we are
1384 using gcc and the type is of a special size. */
1385 /* As of about 31 Mar 93, GCC was changed to be compatible with the
1386 native compiler. GCC 2.3.3 was the last release that did it the
1387 old way. Since gcc2_compiled was not changed, we have no
1388 way to correctly win in all cases, so we just do the right thing
1389 for gcc1 and for gcc2 after this change. Thus it loses for gcc
1390 2.0-2.3.3. This is somewhat unfortunate, but changing gcc2_compiled
1391 would cause more chaos than dealing with some struct returns being
1393 #if !defined (USE_STRUCT_CONVENTION)
1394 #define USE_STRUCT_CONVENTION(gcc_p, type)\
1395 (!((gcc_p == 1) && (TYPE_LENGTH (value_type) == 1 \
1396 || TYPE_LENGTH (value_type) == 2 \
1397 || TYPE_LENGTH (value_type) == 4 \
1398 || TYPE_LENGTH (value_type) == 8 \
1403 /* Return true if the function specified is using the structure returning
1404 convention on this machine to return arguments, or 0 if it is using
1405 the value returning convention. FUNCTION is the value representing
1406 the function, FUNCADDR is the address of the function, and VALUE_TYPE
1407 is the type returned by the function. GCC_P is nonzero if compiled
1411 using_struct_return (function, funcaddr, value_type, gcc_p)
1414 struct type *value_type;
1418 register enum type_code code = TYPE_CODE (value_type);
1420 if (code == TYPE_CODE_ERROR)
1421 error ("Function return type unknown.");
1423 if (code == TYPE_CODE_STRUCT ||
1424 code == TYPE_CODE_UNION ||
1425 code == TYPE_CODE_ARRAY)
1426 return USE_STRUCT_CONVENTION (gcc_p, value_type);
1431 /* Store VAL so it will be returned if a function returns now.
1432 Does not verify that VAL's type matches what the current
1433 function wants to return. */
1436 set_return_value (val)
1439 register enum type_code code = TYPE_CODE (VALUE_TYPE (val));
1443 if (code == TYPE_CODE_ERROR)
1444 error ("Function return type unknown.");
1446 if ( code == TYPE_CODE_STRUCT
1447 || code == TYPE_CODE_UNION) /* FIXME, implement struct return. */
1448 error ("GDB does not support specifying a struct or union return value.");
1450 /* FIXME, this is bogus. We don't know what the return conventions
1451 are, or how values should be promoted.... */
1452 if (code == TYPE_CODE_FLT)
1454 dbuf = value_as_double (val);
1456 STORE_RETURN_VALUE (VALUE_TYPE (val), (char *)&dbuf);
1460 lbuf = value_as_long (val);
1461 STORE_RETURN_VALUE (VALUE_TYPE (val), (char *)&lbuf);
1466 _initialize_values ()
1468 add_cmd ("convenience", no_class, show_convenience,
1469 "Debugger convenience (\"$foo\") variables.\n\
1470 These variables are created when you assign them values;\n\
1471 thus, \"print $foo=1\" gives \"$foo\" the value 1. Values may be any type.\n\n\
1472 A few convenience variables are given values automatically:\n\
1473 \"$_\"holds the last address examined with \"x\" or \"info lines\",\n\
1474 \"$__\" holds the contents of the last address examined with \"x\".",
1477 add_cmd ("values", no_class, show_values,
1478 "Elements of value history around item number IDX (or last ten).",