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 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 *typename = type_name_no_tag (type);
101 return (typename != NULL && !strcmp (typename, 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 volatile struct gdb_exception ex;
317 struct value *v = NULL;
319 TRY_CATCH (ex, RETURN_MASK_ERROR)
321 v = value_static_field (type, i);
325 fprintf_filtered (stream,
326 _("<error reading variable: %s>"),
328 cp_print_static_field (TYPE_FIELD_TYPE (type, i),
329 v, stream, recurse + 1,
332 else if (i == vptr_fieldno && type == vptr_basetype)
334 int i_offset = offset + TYPE_FIELD_BITPOS (type, i) / 8;
335 struct type *i_type = TYPE_FIELD_TYPE (type, i);
337 if (valprint_check_validity (stream, i_type, i_offset, val))
341 addr = extract_typed_address (valaddr + i_offset, i_type);
342 print_function_pointer_address (options,
343 get_type_arch (type),
349 struct value_print_options opts = *options;
352 val_print (TYPE_FIELD_TYPE (type, i),
354 offset + TYPE_FIELD_BITPOS (type, i) / 8,
356 stream, recurse + 1, val, &opts,
360 annotate_field_end ();
363 if (dont_print_statmem == 0)
365 size_t obstack_final_size =
366 obstack_object_size (&dont_print_statmem_obstack);
368 if (obstack_final_size > statmem_obstack_initial_size)
370 /* In effect, a pop of the printed-statics stack. */
373 (char *) obstack_next_free (&dont_print_statmem_obstack) -
374 (obstack_final_size - statmem_obstack_initial_size);
376 obstack_free (&dont_print_statmem_obstack,
380 if (last_set_recurse != recurse)
382 size_t obstack_final_size =
383 obstack_object_size (&dont_print_stat_array_obstack);
385 if (obstack_final_size > stat_array_obstack_initial_size)
388 (char *) obstack_next_free (&dont_print_stat_array_obstack)
389 - (obstack_final_size
390 - stat_array_obstack_initial_size);
392 obstack_free (&dont_print_stat_array_obstack,
395 last_set_recurse = -1;
399 if (options->prettyformat)
401 fprintf_filtered (stream, "\n");
402 print_spaces_filtered (2 * recurse, stream);
404 } /* if there are data fields */
406 fprintf_filtered (stream, "}");
409 /* Like cp_print_value_fields, but find the runtime type of the object
410 and pass it as the `real_type' argument to cp_print_value_fields.
411 This function is a hack to work around the fact that
412 common_val_print passes the embedded offset to val_print, but not
413 the enclosing type. */
416 cp_print_value_fields_rtti (struct type *type,
417 const gdb_byte *valaddr, int offset,
419 struct ui_file *stream, int recurse,
420 const struct value *val,
421 const struct value_print_options *options,
422 struct type **dont_print_vb,
423 int dont_print_statmem)
425 struct type *real_type = NULL;
427 /* We require all bits to be valid in order to attempt a
429 if (!value_bits_any_optimized_out (val,
430 TARGET_CHAR_BIT * offset,
431 TARGET_CHAR_BIT * TYPE_LENGTH (type)))
434 int full, top, using_enc;
436 /* Ugh, we have to convert back to a value here. */
437 value = value_from_contents_and_address (type, valaddr + offset,
439 type = value_type (value);
440 /* We don't actually care about most of the result here -- just
441 the type. We already have the correct offset, due to how
442 val_print was initially called. */
443 real_type = value_rtti_type (value, &full, &top, &using_enc);
449 cp_print_value_fields (type, real_type, valaddr, offset,
450 address, stream, recurse, val, options,
451 dont_print_vb, dont_print_statmem);
454 /* Special val_print routine to avoid printing multiple copies of
455 virtual baseclasses. */
458 cp_print_value (struct type *type, struct type *real_type,
459 const gdb_byte *valaddr, int offset,
460 CORE_ADDR address, struct ui_file *stream,
461 int recurse, const struct value *val,
462 const struct value_print_options *options,
463 struct type **dont_print_vb)
465 struct type **last_dont_print
466 = (struct type **) obstack_next_free (&dont_print_vb_obstack);
467 struct obstack tmp_obstack = dont_print_vb_obstack;
468 int i, n_baseclasses = TYPE_N_BASECLASSES (type);
470 struct type *thistype;
472 if (dont_print_vb == 0)
474 /* If we're at top level, carve out a completely fresh chunk of
475 the obstack and use that until this particular invocation
477 /* Bump up the high-water mark. Now alpha is omega. */
478 obstack_finish (&dont_print_vb_obstack);
481 for (i = 0; i < n_baseclasses; i++)
485 struct type *baseclass = check_typedef (TYPE_BASECLASS (type, i));
486 const char *basename = TYPE_NAME (baseclass);
487 const gdb_byte *base_valaddr = NULL;
488 const struct value *base_val = NULL;
489 volatile struct gdb_exception ex;
491 if (BASETYPE_VIA_VIRTUAL (type, i))
493 struct type **first_dont_print
494 = (struct type **) obstack_base (&dont_print_vb_obstack);
496 int j = (struct type **)
497 obstack_next_free (&dont_print_vb_obstack) - first_dont_print;
500 if (baseclass == first_dont_print[j])
503 obstack_ptr_grow (&dont_print_vb_obstack, baseclass);
507 thistype = real_type;
509 TRY_CATCH (ex, RETURN_MASK_ERROR)
511 boffset = baseclass_offset (type, i, valaddr, offset, address, val);
513 if (ex.reason < 0 && ex.error == NOT_AVAILABLE_ERROR)
515 else if (ex.reason < 0)
521 if (BASETYPE_VIA_VIRTUAL (type, i))
523 /* The virtual base class pointer might have been
524 clobbered by the user program. Make sure that it
525 still points to a valid memory location. */
527 if ((boffset + offset) < 0
528 || (boffset + offset) >= TYPE_LENGTH (real_type))
531 struct cleanup *back_to;
533 buf = xmalloc (TYPE_LENGTH (baseclass));
534 back_to = make_cleanup (xfree, buf);
536 if (target_read_memory (address + boffset, buf,
537 TYPE_LENGTH (baseclass)) != 0)
539 base_val = value_from_contents_and_address (baseclass,
542 baseclass = value_type (base_val);
545 thistype = baseclass;
546 base_valaddr = value_contents_for_printing_const (base_val);
547 do_cleanups (back_to);
551 base_valaddr = valaddr;
557 base_valaddr = valaddr;
562 /* Now do the printing. */
563 if (options->prettyformat)
565 fprintf_filtered (stream, "\n");
566 print_spaces_filtered (2 * recurse, stream);
568 fputs_filtered ("<", stream);
569 /* Not sure what the best notation is in the case where there is
570 no baseclass name. */
571 fputs_filtered (basename ? basename : "", stream);
572 fputs_filtered ("> = ", stream);
575 val_print_unavailable (stream);
577 val_print_invalid_address (stream);
582 /* Attempt to run an extension language pretty-printer on the
583 baseclass if possible. */
586 = apply_ext_lang_val_pretty_printer (baseclass, base_valaddr,
587 thisoffset + boffset,
588 value_address (base_val),
594 cp_print_value_fields (baseclass, thistype, base_valaddr,
595 thisoffset + boffset,
596 value_address (base_val),
597 stream, recurse, base_val, options,
599 obstack_base (&dont_print_vb_obstack)),
602 fputs_filtered (", ", stream);
608 if (dont_print_vb == 0)
610 /* Free the space used to deal with the printing
611 of this type from top level. */
612 obstack_free (&dont_print_vb_obstack, last_dont_print);
613 /* Reset watermark so that we can continue protecting
614 ourselves from whatever we were protecting ourselves. */
615 dont_print_vb_obstack = tmp_obstack;
619 /* Print value of a static member. To avoid infinite recursion when
620 printing a class that contains a static instance of the class, we
621 keep the addresses of all printed static member classes in an
622 obstack and refuse to print them more than once.
624 VAL contains the value to print, TYPE, STREAM, RECURSE, and OPTIONS
625 have the same meanings as in c_val_print. */
628 cp_print_static_field (struct type *type,
630 struct ui_file *stream,
632 const struct value_print_options *options)
634 struct value_print_options opts;
636 if (value_entirely_optimized_out (val))
638 val_print_optimized_out (val, stream);
642 if (TYPE_CODE (type) == TYPE_CODE_STRUCT)
644 CORE_ADDR *first_dont_print;
649 = (CORE_ADDR *) obstack_base (&dont_print_statmem_obstack);
650 i = obstack_object_size (&dont_print_statmem_obstack)
651 / sizeof (CORE_ADDR);
655 if (value_address (val) == first_dont_print[i])
657 fputs_filtered ("<same as static member of an already"
664 addr = value_address (val);
665 obstack_grow (&dont_print_statmem_obstack, (char *) &addr,
667 CHECK_TYPEDEF (type);
668 cp_print_value_fields (type, value_enclosing_type (val),
669 value_contents_for_printing (val),
670 value_embedded_offset (val), addr,
671 stream, recurse, val,
676 if (TYPE_CODE (type) == TYPE_CODE_ARRAY)
678 struct type **first_dont_print;
680 struct type *target_type = TYPE_TARGET_TYPE (type);
683 = (struct type **) obstack_base (&dont_print_stat_array_obstack);
684 i = obstack_object_size (&dont_print_stat_array_obstack)
685 / sizeof (struct type *);
689 if (target_type == first_dont_print[i])
691 fputs_filtered ("<same as static member of an already"
698 obstack_grow (&dont_print_stat_array_obstack,
699 (char *) &target_type,
700 sizeof (struct type *));
705 val_print (type, value_contents_for_printing (val),
706 value_embedded_offset (val),
708 stream, recurse, val,
709 &opts, current_language);
713 /* Find the field in *DOMAIN, or its non-virtual base classes, with
714 bit offset OFFSET. Set *DOMAIN to the containing type and *FIELDNO
715 to the containing field number. If OFFSET is not exactly at the
716 start of some field, set *DOMAIN to NULL. */
719 cp_find_class_member (struct type **domain_p, int *fieldno,
726 *domain_p = check_typedef (*domain_p);
728 len = TYPE_NFIELDS (domain);
730 for (i = TYPE_N_BASECLASSES (domain); i < len; i++)
732 LONGEST bitpos = TYPE_FIELD_BITPOS (domain, i);
735 if (offset == bitpos)
742 for (i = 0; i < TYPE_N_BASECLASSES (domain); i++)
744 LONGEST bitpos = TYPE_FIELD_BITPOS (domain, i);
745 LONGEST bitsize = 8 * TYPE_LENGTH (TYPE_FIELD_TYPE (domain, i));
747 if (offset >= bitpos && offset < bitpos + bitsize)
749 *domain_p = TYPE_FIELD_TYPE (domain, i);
750 cp_find_class_member (domain_p, fieldno, offset - bitpos);
759 cp_print_class_member (const gdb_byte *valaddr, struct type *type,
760 struct ui_file *stream, char *prefix)
762 enum bfd_endian byte_order = gdbarch_byte_order (get_type_arch (type));
764 /* VAL is a byte offset into the structure type DOMAIN.
765 Find the name of the field for that offset and
767 struct type *domain = TYPE_SELF_TYPE (type);
771 val = extract_signed_integer (valaddr,
775 /* Pointers to data members are usually byte offsets into an object.
776 Because a data member can have offset zero, and a NULL pointer to
777 member must be distinct from any valid non-NULL pointer to
778 member, either the value is biased or the NULL value has a
779 special representation; both are permitted by ISO C++. HP aCC
780 used a bias of 0x20000000; HP cfront used a bias of 1; g++ 3.x
781 and other compilers which use the Itanium ABI use -1 as the NULL
782 value. GDB only supports that last form; to add support for
783 another form, make this into a cp-abi hook. */
787 fprintf_filtered (stream, "NULL");
791 cp_find_class_member (&domain, &fieldno, val << 3);
797 fputs_filtered (prefix, stream);
798 name = type_name_no_tag (domain);
800 fputs_filtered (name, stream);
802 c_type_print_base (domain, stream, 0, 0, &type_print_raw_options);
803 fprintf_filtered (stream, "::");
804 fputs_filtered (TYPE_FIELD_NAME (domain, fieldno), stream);
807 fprintf_filtered (stream, "%ld", (long) val);
812 _initialize_cp_valprint (void)
814 add_setshow_boolean_cmd ("static-members", class_support,
815 &user_print_options.static_field_print, _("\
816 Set printing of C++ static members."), _("\
817 Show printing of C++ static members."), NULL,
819 show_static_field_print,
820 &setprintlist, &showprintlist);
822 add_setshow_boolean_cmd ("vtbl", class_support,
823 &user_print_options.vtblprint, _("\
824 Set printing of C++ virtual function tables."), _("\
825 Show printing of C++ virtual function tables."), NULL,
828 &setprintlist, &showprintlist);
830 add_setshow_boolean_cmd ("object", class_support,
831 &user_print_options.objectprint, _("\
832 Set printing of object's derived type based on vtable info."), _("\
833 Show printing of object's derived type based on vtable info."), NULL,
836 &setprintlist, &showprintlist);
838 obstack_begin (&dont_print_stat_array_obstack,
839 32 * sizeof (struct type *));
840 obstack_begin (&dont_print_statmem_obstack,
841 32 * sizeof (CORE_ADDR));
842 obstack_begin (&dont_print_vb_obstack,
843 32 * sizeof (struct type *));