1 /* Support for printing C++ values for GDB, the GNU debugger.
3 Copyright (C) 1986-2016 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 *, LONGEST,
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 extern 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, LONGEST 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 type = 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, LONGEST 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)))
440 /* Ugh, we have to convert back to a value here. */
441 value = value_from_contents_and_address (type, valaddr + offset,
443 type = value_type (value);
444 /* We don't actually care about most of the result here -- just
445 the type. We already have the correct offset, due to how
446 val_print was initially called. */
447 real_type = value_rtti_type (value, &full, &top, &using_enc);
453 cp_print_value_fields (type, real_type, valaddr, offset,
454 address, stream, recurse, val, options,
455 dont_print_vb, dont_print_statmem);
458 /* Special val_print routine to avoid printing multiple copies of
459 virtual baseclasses. */
462 cp_print_value (struct type *type, struct type *real_type,
463 const gdb_byte *valaddr, LONGEST offset,
464 CORE_ADDR address, struct ui_file *stream,
465 int recurse, const struct value *val,
466 const struct value_print_options *options,
467 struct type **dont_print_vb)
469 struct type **last_dont_print
470 = (struct type **) obstack_next_free (&dont_print_vb_obstack);
471 struct obstack tmp_obstack = dont_print_vb_obstack;
472 int i, n_baseclasses = TYPE_N_BASECLASSES (type);
474 struct type *thistype;
476 if (dont_print_vb == 0)
478 /* If we're at top level, carve out a completely fresh chunk of
479 the obstack and use that until this particular invocation
481 /* Bump up the high-water mark. Now alpha is omega. */
482 obstack_finish (&dont_print_vb_obstack);
485 for (i = 0; i < n_baseclasses; i++)
489 struct type *baseclass = check_typedef (TYPE_BASECLASS (type, i));
490 const char *basename = TYPE_NAME (baseclass);
491 const gdb_byte *base_valaddr = NULL;
492 const struct value *base_val = NULL;
494 if (BASETYPE_VIA_VIRTUAL (type, i))
496 struct type **first_dont_print
497 = (struct type **) obstack_base (&dont_print_vb_obstack);
499 int j = (struct type **)
500 obstack_next_free (&dont_print_vb_obstack) - first_dont_print;
503 if (baseclass == first_dont_print[j])
506 obstack_ptr_grow (&dont_print_vb_obstack, baseclass);
510 thistype = real_type;
514 boffset = baseclass_offset (type, i, valaddr, offset, address, val);
516 CATCH (ex, RETURN_MASK_ERROR)
518 if (ex.error == NOT_AVAILABLE_ERROR)
527 if (BASETYPE_VIA_VIRTUAL (type, i))
529 /* The virtual base class pointer might have been
530 clobbered by the user program. Make sure that it
531 still points to a valid memory location. */
533 if ((boffset + offset) < 0
534 || (boffset + offset) >= TYPE_LENGTH (real_type))
537 struct cleanup *back_to;
539 buf = (gdb_byte *) xmalloc (TYPE_LENGTH (baseclass));
540 back_to = make_cleanup (xfree, buf);
542 if (target_read_memory (address + boffset, buf,
543 TYPE_LENGTH (baseclass)) != 0)
545 base_val = value_from_contents_and_address (baseclass,
548 baseclass = value_type (base_val);
551 thistype = baseclass;
552 base_valaddr = value_contents_for_printing_const (base_val);
553 do_cleanups (back_to);
557 base_valaddr = valaddr;
563 base_valaddr = valaddr;
568 /* Now do the printing. */
569 if (options->prettyformat)
571 fprintf_filtered (stream, "\n");
572 print_spaces_filtered (2 * recurse, stream);
574 fputs_filtered ("<", stream);
575 /* Not sure what the best notation is in the case where there is
576 no baseclass name. */
577 fputs_filtered (basename ? basename : "", stream);
578 fputs_filtered ("> = ", stream);
581 val_print_unavailable (stream);
583 val_print_invalid_address (stream);
588 /* Attempt to run an extension language pretty-printer on the
589 baseclass if possible. */
592 = apply_ext_lang_val_pretty_printer (baseclass, base_valaddr,
593 thisoffset + boffset,
594 value_address (base_val),
600 cp_print_value_fields (baseclass, thistype, base_valaddr,
601 thisoffset + boffset,
602 value_address (base_val),
603 stream, recurse, base_val, options,
605 obstack_base (&dont_print_vb_obstack)),
608 fputs_filtered (", ", stream);
614 if (dont_print_vb == 0)
616 /* Free the space used to deal with the printing
617 of this type from top level. */
618 obstack_free (&dont_print_vb_obstack, last_dont_print);
619 /* Reset watermark so that we can continue protecting
620 ourselves from whatever we were protecting ourselves. */
621 dont_print_vb_obstack = tmp_obstack;
625 /* Print value of a static member. To avoid infinite recursion when
626 printing a class that contains a static instance of the class, we
627 keep the addresses of all printed static member classes in an
628 obstack and refuse to print them more than once.
630 VAL contains the value to print, TYPE, STREAM, RECURSE, and OPTIONS
631 have the same meanings as in c_val_print. */
634 cp_print_static_field (struct type *type,
636 struct ui_file *stream,
638 const struct value_print_options *options)
640 struct value_print_options opts;
642 if (value_entirely_optimized_out (val))
644 val_print_optimized_out (val, stream);
648 if (TYPE_CODE (type) == TYPE_CODE_STRUCT)
650 CORE_ADDR *first_dont_print;
655 = (CORE_ADDR *) obstack_base (&dont_print_statmem_obstack);
656 i = obstack_object_size (&dont_print_statmem_obstack)
657 / sizeof (CORE_ADDR);
661 if (value_address (val) == first_dont_print[i])
663 fputs_filtered ("<same as static member of an already"
670 addr = value_address (val);
671 obstack_grow (&dont_print_statmem_obstack, (char *) &addr,
673 type = check_typedef (type);
674 cp_print_value_fields (type, value_enclosing_type (val),
675 value_contents_for_printing (val),
676 value_embedded_offset (val), addr,
677 stream, recurse, val,
682 if (TYPE_CODE (type) == TYPE_CODE_ARRAY)
684 struct type **first_dont_print;
686 struct type *target_type = TYPE_TARGET_TYPE (type);
689 = (struct type **) obstack_base (&dont_print_stat_array_obstack);
690 i = obstack_object_size (&dont_print_stat_array_obstack)
691 / sizeof (struct type *);
695 if (target_type == first_dont_print[i])
697 fputs_filtered ("<same as static member of an already"
704 obstack_grow (&dont_print_stat_array_obstack,
705 (char *) &target_type,
706 sizeof (struct type *));
711 val_print (type, value_contents_for_printing (val),
712 value_embedded_offset (val),
714 stream, recurse, val,
715 &opts, current_language);
718 /* Find the field in *SELF, or its non-virtual base classes, with
719 bit offset OFFSET. Set *SELF to the containing type and *FIELDNO
720 to the containing field number. If OFFSET is not exactly at the
721 start of some field, set *SELF to NULL. */
724 cp_find_class_member (struct type **self_p, int *fieldno,
731 *self_p = check_typedef (*self_p);
733 len = TYPE_NFIELDS (self);
735 for (i = TYPE_N_BASECLASSES (self); i < len; i++)
737 LONGEST bitpos = TYPE_FIELD_BITPOS (self, i);
740 if (offset == bitpos)
747 for (i = 0; i < TYPE_N_BASECLASSES (self); i++)
749 LONGEST bitpos = TYPE_FIELD_BITPOS (self, i);
750 LONGEST bitsize = 8 * TYPE_LENGTH (TYPE_FIELD_TYPE (self, i));
752 if (offset >= bitpos && offset < bitpos + bitsize)
754 *self_p = TYPE_FIELD_TYPE (self, i);
755 cp_find_class_member (self_p, fieldno, offset - bitpos);
764 cp_print_class_member (const gdb_byte *valaddr, struct type *type,
765 struct ui_file *stream, char *prefix)
767 enum bfd_endian byte_order = gdbarch_byte_order (get_type_arch (type));
769 /* VAL is a byte offset into the structure type SELF_TYPE.
770 Find the name of the field for that offset and
772 struct type *self_type = TYPE_SELF_TYPE (type);
776 val = extract_signed_integer (valaddr,
780 /* Pointers to data members are usually byte offsets into an object.
781 Because a data member can have offset zero, and a NULL pointer to
782 member must be distinct from any valid non-NULL pointer to
783 member, either the value is biased or the NULL value has a
784 special representation; both are permitted by ISO C++. HP aCC
785 used a bias of 0x20000000; HP cfront used a bias of 1; g++ 3.x
786 and other compilers which use the Itanium ABI use -1 as the NULL
787 value. GDB only supports that last form; to add support for
788 another form, make this into a cp-abi hook. */
792 fprintf_filtered (stream, "NULL");
796 cp_find_class_member (&self_type, &fieldno, val << 3);
798 if (self_type != NULL)
802 fputs_filtered (prefix, stream);
803 name = type_name_no_tag (self_type);
805 fputs_filtered (name, stream);
807 c_type_print_base (self_type, stream, 0, 0, &type_print_raw_options);
808 fprintf_filtered (stream, "::");
809 fputs_filtered (TYPE_FIELD_NAME (self_type, fieldno), stream);
812 fprintf_filtered (stream, "%ld", (long) val);
817 _initialize_cp_valprint (void)
819 add_setshow_boolean_cmd ("static-members", class_support,
820 &user_print_options.static_field_print, _("\
821 Set printing of C++ static members."), _("\
822 Show printing of C++ static members."), NULL,
824 show_static_field_print,
825 &setprintlist, &showprintlist);
827 add_setshow_boolean_cmd ("vtbl", class_support,
828 &user_print_options.vtblprint, _("\
829 Set printing of C++ virtual function tables."), _("\
830 Show printing of C++ virtual function tables."), NULL,
833 &setprintlist, &showprintlist);
835 add_setshow_boolean_cmd ("object", class_support,
836 &user_print_options.objectprint, _("\
837 Set printing of object's derived type based on vtable info."), _("\
838 Show printing of object's derived type based on vtable info."), NULL,
841 &setprintlist, &showprintlist);
843 obstack_begin (&dont_print_stat_array_obstack,
844 32 * sizeof (struct type *));
845 obstack_begin (&dont_print_statmem_obstack,
846 32 * sizeof (CORE_ADDR));
847 obstack_begin (&dont_print_vb_obstack,
848 32 * sizeof (struct type *));