1 /* Support for printing C++ values for GDB, the GNU debugger.
3 Copyright (C) 1986-2015 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 3 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, see <http://www.gnu.org/licenses/>. */
21 #include "gdb_obstack.h"
24 #include "expression.h"
34 #include "cp-support.h"
36 #include "extension.h"
37 #include "typeprint.h"
39 /* Controls printing of vtbl's. */
41 show_vtblprint (struct ui_file *file, int from_tty,
42 struct cmd_list_element *c, const char *value)
44 fprintf_filtered (file, _("\
45 Printing of C++ virtual function tables is %s.\n"),
49 /* Controls looking up an object's derived type using what we find in
52 show_objectprint (struct ui_file *file, int from_tty,
53 struct cmd_list_element *c,
56 fprintf_filtered (file, _("\
57 Printing of object's derived type based on vtable info is %s.\n"),
62 show_static_field_print (struct ui_file *file, int from_tty,
63 struct cmd_list_element *c,
66 fprintf_filtered (file,
67 _("Printing of C++ static members is %s.\n"),
72 static struct obstack dont_print_vb_obstack;
73 static struct obstack dont_print_statmem_obstack;
74 static struct obstack dont_print_stat_array_obstack;
76 extern void _initialize_cp_valprint (void);
78 static void cp_print_static_field (struct type *, struct value *,
79 struct ui_file *, int,
80 const struct value_print_options *);
82 static void cp_print_value (struct type *, struct type *,
83 const gdb_byte *, int,
84 CORE_ADDR, struct ui_file *,
85 int, const struct value *,
86 const struct value_print_options *,
90 /* GCC versions after 2.4.5 use this. */
91 EXPORTED_CONST char vtbl_ptr_name[] = "__vtbl_ptr_type";
93 /* Return truth value for assertion that TYPE is of the type
94 "pointer to virtual function". */
97 cp_is_vtbl_ptr_type (struct type *type)
99 const char *type_name = type_name_no_tag (type);
101 return (type_name != NULL && !strcmp (type_name, vtbl_ptr_name));
104 /* Return truth value for the assertion that TYPE is of the type
105 "pointer to virtual function table". */
108 cp_is_vtbl_member (struct type *type)
110 /* With older versions of g++, the vtbl field pointed to an array of
111 structures. Nowadays it points directly to the structure. */
112 if (TYPE_CODE (type) == TYPE_CODE_PTR)
114 type = TYPE_TARGET_TYPE (type);
115 if (TYPE_CODE (type) == TYPE_CODE_ARRAY)
117 type = TYPE_TARGET_TYPE (type);
118 if (TYPE_CODE (type) == TYPE_CODE_STRUCT /* if not using thunks */
119 || TYPE_CODE (type) == TYPE_CODE_PTR) /* if using thunks */
121 /* Virtual functions tables are full of pointers
122 to virtual functions. */
123 return cp_is_vtbl_ptr_type (type);
126 else if (TYPE_CODE (type) == TYPE_CODE_STRUCT) /* if not using thunks */
128 return cp_is_vtbl_ptr_type (type);
130 else if (TYPE_CODE (type) == TYPE_CODE_PTR) /* if using thunks */
132 /* The type name of the thunk pointer is NULL when using
133 dwarf2. We could test for a pointer to a function, but
134 there is no type info for the virtual table either, so it
136 return cp_is_vtbl_ptr_type (type);
142 /* Mutually recursive subroutines of cp_print_value and c_val_print to
143 print out a structure's fields: cp_print_value_fields and
146 TYPE, VALADDR, ADDRESS, STREAM, RECURSE, and OPTIONS have the same
147 meanings as in cp_print_value and c_val_print.
149 2nd argument REAL_TYPE is used to carry over the type of the
150 derived class across the recursion to base classes.
152 DONT_PRINT is an array of baseclass types that we should not print,
153 or zero if called from top level. */
156 cp_print_value_fields (struct type *type, struct type *real_type,
157 const gdb_byte *valaddr, int offset,
158 CORE_ADDR address, struct ui_file *stream,
159 int recurse, const struct value *val,
160 const struct value_print_options *options,
161 struct type **dont_print_vb,
162 int dont_print_statmem)
164 int i, len, n_baseclasses;
166 static int last_set_recurse = -1;
168 CHECK_TYPEDEF (type);
172 /* Any object can be left on obstacks only during an unexpected
175 if (obstack_object_size (&dont_print_statmem_obstack) > 0)
177 obstack_free (&dont_print_statmem_obstack, NULL);
178 obstack_begin (&dont_print_statmem_obstack,
179 32 * sizeof (CORE_ADDR));
181 if (obstack_object_size (&dont_print_stat_array_obstack) > 0)
183 obstack_free (&dont_print_stat_array_obstack, NULL);
184 obstack_begin (&dont_print_stat_array_obstack,
185 32 * sizeof (struct type *));
189 fprintf_filtered (stream, "{");
190 len = TYPE_NFIELDS (type);
191 n_baseclasses = TYPE_N_BASECLASSES (type);
193 /* First, print out baseclasses such that we don't print
194 duplicates of virtual baseclasses. */
196 if (n_baseclasses > 0)
197 cp_print_value (type, real_type, valaddr,
198 offset, address, stream,
199 recurse + 1, val, options,
202 /* Second, print out data fields */
204 /* If there are no data fields, skip this part */
205 if (len == n_baseclasses || !len)
206 fprintf_filtered (stream, "<No data fields>");
209 size_t statmem_obstack_initial_size = 0;
210 size_t stat_array_obstack_initial_size = 0;
211 struct type *vptr_basetype = NULL;
214 if (dont_print_statmem == 0)
216 statmem_obstack_initial_size =
217 obstack_object_size (&dont_print_statmem_obstack);
219 if (last_set_recurse != recurse)
221 stat_array_obstack_initial_size =
222 obstack_object_size (&dont_print_stat_array_obstack);
224 last_set_recurse = recurse;
228 vptr_fieldno = get_vptr_fieldno (type, &vptr_basetype);
229 for (i = n_baseclasses; i < len; i++)
231 /* If requested, skip printing of static fields. */
232 if (!options->static_field_print
233 && field_is_static (&TYPE_FIELD (type, i)))
237 fprintf_filtered (stream, ", ");
238 else if (n_baseclasses > 0)
240 if (options->prettyformat)
242 fprintf_filtered (stream, "\n");
243 print_spaces_filtered (2 + 2 * recurse, stream);
244 fputs_filtered ("members of ", stream);
245 fputs_filtered (type_name_no_tag (type), stream);
246 fputs_filtered (": ", stream);
251 if (options->prettyformat)
253 fprintf_filtered (stream, "\n");
254 print_spaces_filtered (2 + 2 * recurse, stream);
258 wrap_here (n_spaces (2 + 2 * recurse));
261 annotate_field_begin (TYPE_FIELD_TYPE (type, i));
263 if (field_is_static (&TYPE_FIELD (type, i)))
264 fputs_filtered ("static ", stream);
265 fprintf_symbol_filtered (stream,
266 TYPE_FIELD_NAME (type, i),
267 current_language->la_language,
268 DMGL_PARAMS | DMGL_ANSI);
269 annotate_field_name_end ();
270 /* Do not print leading '=' in case of anonymous
272 if (strcmp (TYPE_FIELD_NAME (type, i), ""))
273 fputs_filtered (" = ", stream);
274 annotate_field_value ();
276 if (!field_is_static (&TYPE_FIELD (type, i))
277 && TYPE_FIELD_PACKED (type, i))
281 /* Bitfields require special handling, especially due to
282 byte order problems. */
283 if (TYPE_FIELD_IGNORE (type, i))
285 fputs_filtered ("<optimized out or zero length>", stream);
287 else if (value_bits_synthetic_pointer (val,
288 TYPE_FIELD_BITPOS (type,
290 TYPE_FIELD_BITSIZE (type,
293 fputs_filtered (_("<synthetic pointer>"), stream);
297 struct value_print_options opts = *options;
301 v = value_field_bitfield (type, i, valaddr, offset, val);
303 common_val_print (v, stream, recurse + 1, &opts,
309 if (TYPE_FIELD_IGNORE (type, i))
311 fputs_filtered ("<optimized out or zero length>",
314 else if (field_is_static (&TYPE_FIELD (type, i)))
316 struct value *v = NULL;
320 v = value_static_field (type, i);
323 CATCH (ex, RETURN_MASK_ERROR)
325 fprintf_filtered (stream,
326 _("<error reading variable: %s>"),
331 cp_print_static_field (TYPE_FIELD_TYPE (type, i),
332 v, stream, recurse + 1,
335 else if (i == vptr_fieldno && type == vptr_basetype)
337 int i_offset = offset + TYPE_FIELD_BITPOS (type, i) / 8;
338 struct type *i_type = TYPE_FIELD_TYPE (type, i);
340 if (valprint_check_validity (stream, i_type, i_offset, val))
344 addr = extract_typed_address (valaddr + i_offset, i_type);
345 print_function_pointer_address (options,
346 get_type_arch (type),
352 struct value_print_options opts = *options;
355 val_print (TYPE_FIELD_TYPE (type, i),
357 offset + TYPE_FIELD_BITPOS (type, i) / 8,
359 stream, recurse + 1, val, &opts,
363 annotate_field_end ();
366 if (dont_print_statmem == 0)
368 size_t obstack_final_size =
369 obstack_object_size (&dont_print_statmem_obstack);
371 if (obstack_final_size > statmem_obstack_initial_size)
373 /* In effect, a pop of the printed-statics stack. */
376 (char *) obstack_next_free (&dont_print_statmem_obstack) -
377 (obstack_final_size - statmem_obstack_initial_size);
379 obstack_free (&dont_print_statmem_obstack,
383 if (last_set_recurse != recurse)
385 size_t obstack_final_size =
386 obstack_object_size (&dont_print_stat_array_obstack);
388 if (obstack_final_size > stat_array_obstack_initial_size)
391 (char *) obstack_next_free (&dont_print_stat_array_obstack)
392 - (obstack_final_size
393 - stat_array_obstack_initial_size);
395 obstack_free (&dont_print_stat_array_obstack,
398 last_set_recurse = -1;
402 if (options->prettyformat)
404 fprintf_filtered (stream, "\n");
405 print_spaces_filtered (2 * recurse, stream);
407 } /* if there are data fields */
409 fprintf_filtered (stream, "}");
412 /* Like cp_print_value_fields, but find the runtime type of the object
413 and pass it as the `real_type' argument to cp_print_value_fields.
414 This function is a hack to work around the fact that
415 common_val_print passes the embedded offset to val_print, but not
416 the enclosing type. */
419 cp_print_value_fields_rtti (struct type *type,
420 const gdb_byte *valaddr, int offset,
422 struct ui_file *stream, int recurse,
423 const struct value *val,
424 const struct value_print_options *options,
425 struct type **dont_print_vb,
426 int dont_print_statmem)
428 struct type *real_type = NULL;
430 /* We require all bits to be valid in order to attempt a
432 if (!value_bits_any_optimized_out (val,
433 TARGET_CHAR_BIT * offset,
434 TARGET_CHAR_BIT * TYPE_LENGTH (type)))
437 int full, top, using_enc;
439 /* Ugh, we have to convert back to a value here. */
440 value = value_from_contents_and_address (type, valaddr + offset,
442 type = value_type (value);
443 /* We don't actually care about most of the result here -- just
444 the type. We already have the correct offset, due to how
445 val_print was initially called. */
446 real_type = value_rtti_type (value, &full, &top, &using_enc);
452 cp_print_value_fields (type, real_type, valaddr, offset,
453 address, stream, recurse, val, options,
454 dont_print_vb, dont_print_statmem);
457 /* Special val_print routine to avoid printing multiple copies of
458 virtual baseclasses. */
461 cp_print_value (struct type *type, struct type *real_type,
462 const gdb_byte *valaddr, int offset,
463 CORE_ADDR address, struct ui_file *stream,
464 int recurse, const struct value *val,
465 const struct value_print_options *options,
466 struct type **dont_print_vb)
468 struct type **last_dont_print
469 = (struct type **) obstack_next_free (&dont_print_vb_obstack);
470 struct obstack tmp_obstack = dont_print_vb_obstack;
471 int i, n_baseclasses = TYPE_N_BASECLASSES (type);
473 struct type *thistype;
475 if (dont_print_vb == 0)
477 /* If we're at top level, carve out a completely fresh chunk of
478 the obstack and use that until this particular invocation
480 /* Bump up the high-water mark. Now alpha is omega. */
481 obstack_finish (&dont_print_vb_obstack);
484 for (i = 0; i < n_baseclasses; i++)
488 struct type *baseclass = check_typedef (TYPE_BASECLASS (type, i));
489 const char *basename = TYPE_NAME (baseclass);
490 const gdb_byte *base_valaddr = NULL;
491 const struct value *base_val = NULL;
493 if (BASETYPE_VIA_VIRTUAL (type, i))
495 struct type **first_dont_print
496 = (struct type **) obstack_base (&dont_print_vb_obstack);
498 int j = (struct type **)
499 obstack_next_free (&dont_print_vb_obstack) - first_dont_print;
502 if (baseclass == first_dont_print[j])
505 obstack_ptr_grow (&dont_print_vb_obstack, baseclass);
509 thistype = real_type;
513 boffset = baseclass_offset (type, i, valaddr, offset, address, val);
515 CATCH (ex, RETURN_MASK_ERROR)
517 if (ex.error == NOT_AVAILABLE_ERROR)
526 if (BASETYPE_VIA_VIRTUAL (type, i))
528 /* The virtual base class pointer might have been
529 clobbered by the user program. Make sure that it
530 still points to a valid memory location. */
532 if ((boffset + offset) < 0
533 || (boffset + offset) >= TYPE_LENGTH (real_type))
536 struct cleanup *back_to;
538 buf = xmalloc (TYPE_LENGTH (baseclass));
539 back_to = make_cleanup (xfree, buf);
541 if (target_read_memory (address + boffset, buf,
542 TYPE_LENGTH (baseclass)) != 0)
544 base_val = value_from_contents_and_address (baseclass,
547 baseclass = value_type (base_val);
550 thistype = baseclass;
551 base_valaddr = value_contents_for_printing_const (base_val);
552 do_cleanups (back_to);
556 base_valaddr = valaddr;
562 base_valaddr = valaddr;
567 /* Now do the printing. */
568 if (options->prettyformat)
570 fprintf_filtered (stream, "\n");
571 print_spaces_filtered (2 * recurse, stream);
573 fputs_filtered ("<", stream);
574 /* Not sure what the best notation is in the case where there is
575 no baseclass name. */
576 fputs_filtered (basename ? basename : "", stream);
577 fputs_filtered ("> = ", stream);
580 val_print_unavailable (stream);
582 val_print_invalid_address (stream);
587 /* Attempt to run an extension language pretty-printer on the
588 baseclass if possible. */
591 = apply_ext_lang_val_pretty_printer (baseclass, base_valaddr,
592 thisoffset + boffset,
593 value_address (base_val),
599 cp_print_value_fields (baseclass, thistype, base_valaddr,
600 thisoffset + boffset,
601 value_address (base_val),
602 stream, recurse, base_val, options,
604 obstack_base (&dont_print_vb_obstack)),
607 fputs_filtered (", ", stream);
613 if (dont_print_vb == 0)
615 /* Free the space used to deal with the printing
616 of this type from top level. */
617 obstack_free (&dont_print_vb_obstack, last_dont_print);
618 /* Reset watermark so that we can continue protecting
619 ourselves from whatever we were protecting ourselves. */
620 dont_print_vb_obstack = tmp_obstack;
624 /* Print value of a static member. To avoid infinite recursion when
625 printing a class that contains a static instance of the class, we
626 keep the addresses of all printed static member classes in an
627 obstack and refuse to print them more than once.
629 VAL contains the value to print, TYPE, STREAM, RECURSE, and OPTIONS
630 have the same meanings as in c_val_print. */
633 cp_print_static_field (struct type *type,
635 struct ui_file *stream,
637 const struct value_print_options *options)
639 struct value_print_options opts;
641 if (value_entirely_optimized_out (val))
643 val_print_optimized_out (val, stream);
647 if (TYPE_CODE (type) == TYPE_CODE_STRUCT)
649 CORE_ADDR *first_dont_print;
654 = (CORE_ADDR *) obstack_base (&dont_print_statmem_obstack);
655 i = obstack_object_size (&dont_print_statmem_obstack)
656 / sizeof (CORE_ADDR);
660 if (value_address (val) == first_dont_print[i])
662 fputs_filtered ("<same as static member of an already"
669 addr = value_address (val);
670 obstack_grow (&dont_print_statmem_obstack, (char *) &addr,
672 CHECK_TYPEDEF (type);
673 cp_print_value_fields (type, value_enclosing_type (val),
674 value_contents_for_printing (val),
675 value_embedded_offset (val), addr,
676 stream, recurse, val,
681 if (TYPE_CODE (type) == TYPE_CODE_ARRAY)
683 struct type **first_dont_print;
685 struct type *target_type = TYPE_TARGET_TYPE (type);
688 = (struct type **) obstack_base (&dont_print_stat_array_obstack);
689 i = obstack_object_size (&dont_print_stat_array_obstack)
690 / sizeof (struct type *);
694 if (target_type == first_dont_print[i])
696 fputs_filtered ("<same as static member of an already"
703 obstack_grow (&dont_print_stat_array_obstack,
704 (char *) &target_type,
705 sizeof (struct type *));
710 val_print (type, value_contents_for_printing (val),
711 value_embedded_offset (val),
713 stream, recurse, val,
714 &opts, current_language);
717 /* Find the field in *SELF, or its non-virtual base classes, with
718 bit offset OFFSET. Set *SELF to the containing type and *FIELDNO
719 to the containing field number. If OFFSET is not exactly at the
720 start of some field, set *SELF to NULL. */
723 cp_find_class_member (struct type **self_p, int *fieldno,
730 *self_p = check_typedef (*self_p);
732 len = TYPE_NFIELDS (self);
734 for (i = TYPE_N_BASECLASSES (self); i < len; i++)
736 LONGEST bitpos = TYPE_FIELD_BITPOS (self, i);
739 if (offset == bitpos)
746 for (i = 0; i < TYPE_N_BASECLASSES (self); i++)
748 LONGEST bitpos = TYPE_FIELD_BITPOS (self, i);
749 LONGEST bitsize = 8 * TYPE_LENGTH (TYPE_FIELD_TYPE (self, i));
751 if (offset >= bitpos && offset < bitpos + bitsize)
753 *self_p = TYPE_FIELD_TYPE (self, i);
754 cp_find_class_member (self_p, fieldno, offset - bitpos);
763 cp_print_class_member (const gdb_byte *valaddr, struct type *type,
764 struct ui_file *stream, char *prefix)
766 enum bfd_endian byte_order = gdbarch_byte_order (get_type_arch (type));
768 /* VAL is a byte offset into the structure type SELF_TYPE.
769 Find the name of the field for that offset and
771 struct type *self_type = TYPE_SELF_TYPE (type);
775 val = extract_signed_integer (valaddr,
779 /* Pointers to data members are usually byte offsets into an object.
780 Because a data member can have offset zero, and a NULL pointer to
781 member must be distinct from any valid non-NULL pointer to
782 member, either the value is biased or the NULL value has a
783 special representation; both are permitted by ISO C++. HP aCC
784 used a bias of 0x20000000; HP cfront used a bias of 1; g++ 3.x
785 and other compilers which use the Itanium ABI use -1 as the NULL
786 value. GDB only supports that last form; to add support for
787 another form, make this into a cp-abi hook. */
791 fprintf_filtered (stream, "NULL");
795 cp_find_class_member (&self_type, &fieldno, val << 3);
797 if (self_type != NULL)
801 fputs_filtered (prefix, stream);
802 name = type_name_no_tag (self_type);
804 fputs_filtered (name, stream);
806 c_type_print_base (self_type, stream, 0, 0, &type_print_raw_options);
807 fprintf_filtered (stream, "::");
808 fputs_filtered (TYPE_FIELD_NAME (self_type, fieldno), stream);
811 fprintf_filtered (stream, "%ld", (long) val);
816 _initialize_cp_valprint (void)
818 add_setshow_boolean_cmd ("static-members", class_support,
819 &user_print_options.static_field_print, _("\
820 Set printing of C++ static members."), _("\
821 Show printing of C++ static members."), NULL,
823 show_static_field_print,
824 &setprintlist, &showprintlist);
826 add_setshow_boolean_cmd ("vtbl", class_support,
827 &user_print_options.vtblprint, _("\
828 Set printing of C++ virtual function tables."), _("\
829 Show printing of C++ virtual function tables."), NULL,
832 &setprintlist, &showprintlist);
834 add_setshow_boolean_cmd ("object", class_support,
835 &user_print_options.objectprint, _("\
836 Set printing of object's derived type based on vtable info."), _("\
837 Show printing of object's derived type based on vtable info."), NULL,
840 &setprintlist, &showprintlist);
842 obstack_begin (&dont_print_stat_array_obstack,
843 32 * sizeof (struct type *));
844 obstack_begin (&dont_print_statmem_obstack,
845 32 * sizeof (CORE_ADDR));
846 obstack_begin (&dont_print_vb_obstack,
847 32 * sizeof (struct type *));