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 *,
84 CORE_ADDR, struct ui_file *,
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,
158 CORE_ADDR address, struct ui_file *stream,
159 int recurse, 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,
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 const gdb_byte *valaddr = value_contents_for_printing (val);
233 /* If requested, skip printing of static fields. */
234 if (!options->static_field_print
235 && field_is_static (&TYPE_FIELD (type, i)))
239 fprintf_filtered (stream, ", ");
240 else if (n_baseclasses > 0)
242 if (options->prettyformat)
244 fprintf_filtered (stream, "\n");
245 print_spaces_filtered (2 + 2 * recurse, stream);
246 fputs_filtered ("members of ", stream);
247 fputs_filtered (type_name_no_tag (type), stream);
248 fputs_filtered (": ", stream);
253 if (options->prettyformat)
255 fprintf_filtered (stream, "\n");
256 print_spaces_filtered (2 + 2 * recurse, stream);
260 wrap_here (n_spaces (2 + 2 * recurse));
263 annotate_field_begin (TYPE_FIELD_TYPE (type, i));
265 if (field_is_static (&TYPE_FIELD (type, i)))
266 fputs_filtered ("static ", stream);
267 fprintf_symbol_filtered (stream,
268 TYPE_FIELD_NAME (type, i),
269 current_language->la_language,
270 DMGL_PARAMS | DMGL_ANSI);
271 annotate_field_name_end ();
272 /* Do not print leading '=' in case of anonymous
274 if (strcmp (TYPE_FIELD_NAME (type, i), ""))
275 fputs_filtered (" = ", stream);
276 annotate_field_value ();
278 if (!field_is_static (&TYPE_FIELD (type, i))
279 && TYPE_FIELD_PACKED (type, i))
283 /* Bitfields require special handling, especially due to
284 byte order problems. */
285 if (TYPE_FIELD_IGNORE (type, i))
287 fputs_filtered ("<optimized out or zero length>", stream);
289 else if (value_bits_synthetic_pointer (val,
290 TYPE_FIELD_BITPOS (type,
292 TYPE_FIELD_BITSIZE (type,
295 fputs_filtered (_("<synthetic pointer>"), stream);
299 struct value_print_options opts = *options;
303 v = value_field_bitfield (type, i, valaddr, offset, val);
305 common_val_print (v, stream, recurse + 1, &opts,
311 if (TYPE_FIELD_IGNORE (type, i))
313 fputs_filtered ("<optimized out or zero length>",
316 else if (field_is_static (&TYPE_FIELD (type, i)))
318 struct value *v = NULL;
322 v = value_static_field (type, i);
325 CATCH (ex, RETURN_MASK_ERROR)
327 fprintf_filtered (stream,
328 _("<error reading variable: %s>"),
333 cp_print_static_field (TYPE_FIELD_TYPE (type, i),
334 v, stream, recurse + 1,
337 else if (i == vptr_fieldno && type == vptr_basetype)
339 int i_offset = offset + TYPE_FIELD_BITPOS (type, i) / 8;
340 struct type *i_type = TYPE_FIELD_TYPE (type, i);
342 if (valprint_check_validity (stream, i_type, i_offset, val))
346 addr = extract_typed_address (valaddr + i_offset, i_type);
347 print_function_pointer_address (options,
348 get_type_arch (type),
354 struct value_print_options opts = *options;
357 val_print (TYPE_FIELD_TYPE (type, i),
358 offset + TYPE_FIELD_BITPOS (type, i) / 8,
360 stream, recurse + 1, val, &opts,
364 annotate_field_end ();
367 if (dont_print_statmem == 0)
369 size_t obstack_final_size =
370 obstack_object_size (&dont_print_statmem_obstack);
372 if (obstack_final_size > statmem_obstack_initial_size)
374 /* In effect, a pop of the printed-statics stack. */
377 (char *) obstack_next_free (&dont_print_statmem_obstack) -
378 (obstack_final_size - statmem_obstack_initial_size);
380 obstack_free (&dont_print_statmem_obstack,
384 if (last_set_recurse != recurse)
386 size_t obstack_final_size =
387 obstack_object_size (&dont_print_stat_array_obstack);
389 if (obstack_final_size > stat_array_obstack_initial_size)
392 (char *) obstack_next_free (&dont_print_stat_array_obstack)
393 - (obstack_final_size
394 - stat_array_obstack_initial_size);
396 obstack_free (&dont_print_stat_array_obstack,
399 last_set_recurse = -1;
403 if (options->prettyformat)
405 fprintf_filtered (stream, "\n");
406 print_spaces_filtered (2 * recurse, stream);
408 } /* if there are data fields */
410 fprintf_filtered (stream, "}");
413 /* Like cp_print_value_fields, but find the runtime type of the object
414 and pass it as the `real_type' argument to cp_print_value_fields.
415 This function is a hack to work around the fact that
416 common_val_print passes the embedded offset to val_print, but not
417 the enclosing type. */
420 cp_print_value_fields_rtti (struct type *type,
421 const gdb_byte *valaddr, LONGEST offset,
423 struct ui_file *stream, int recurse,
425 const struct value_print_options *options,
426 struct type **dont_print_vb,
427 int dont_print_statmem)
429 struct type *real_type = NULL;
431 /* We require all bits to be valid in order to attempt a
433 if (!value_bits_any_optimized_out (val,
434 TARGET_CHAR_BIT * offset,
435 TARGET_CHAR_BIT * TYPE_LENGTH (type)))
441 /* Ugh, we have to convert back to a value here. */
442 value = value_from_contents_and_address (type, valaddr + offset,
444 type = value_type (value);
445 /* We don't actually care about most of the result here -- just
446 the type. We already have the correct offset, due to how
447 val_print was initially called. */
448 real_type = value_rtti_type (value, &full, &top, &using_enc);
454 cp_print_value_fields (type, real_type, offset,
455 address, stream, recurse, val, options,
456 dont_print_vb, dont_print_statmem);
459 /* Special val_print routine to avoid printing multiple copies of
460 virtual baseclasses. */
463 cp_print_value (struct type *type, struct type *real_type,
465 CORE_ADDR address, struct ui_file *stream,
466 int recurse, struct value *val,
467 const struct value_print_options *options,
468 struct type **dont_print_vb)
470 struct type **last_dont_print
471 = (struct type **) obstack_next_free (&dont_print_vb_obstack);
472 struct obstack tmp_obstack = dont_print_vb_obstack;
473 int i, n_baseclasses = TYPE_N_BASECLASSES (type);
475 struct type *thistype;
476 const gdb_byte *valaddr = value_contents_for_printing (val);
478 if (dont_print_vb == 0)
480 /* If we're at top level, carve out a completely fresh chunk of
481 the obstack and use that until this particular invocation
483 /* Bump up the high-water mark. Now alpha is omega. */
484 obstack_finish (&dont_print_vb_obstack);
487 for (i = 0; i < n_baseclasses; i++)
491 struct type *baseclass = check_typedef (TYPE_BASECLASS (type, i));
492 const char *basename = TYPE_NAME (baseclass);
493 const gdb_byte *base_valaddr = NULL;
494 struct value *base_val = NULL;
496 if (BASETYPE_VIA_VIRTUAL (type, i))
498 struct type **first_dont_print
499 = (struct type **) obstack_base (&dont_print_vb_obstack);
501 int j = (struct type **)
502 obstack_next_free (&dont_print_vb_obstack) - first_dont_print;
505 if (baseclass == first_dont_print[j])
508 obstack_ptr_grow (&dont_print_vb_obstack, baseclass);
512 thistype = real_type;
516 boffset = baseclass_offset (type, i, valaddr, offset, address, val);
518 CATCH (ex, RETURN_MASK_ERROR)
520 if (ex.error == NOT_AVAILABLE_ERROR)
529 if (BASETYPE_VIA_VIRTUAL (type, i))
531 /* The virtual base class pointer might have been
532 clobbered by the user program. Make sure that it
533 still points to a valid memory location. */
535 if ((boffset + offset) < 0
536 || (boffset + offset) >= TYPE_LENGTH (real_type))
539 struct cleanup *back_to;
541 buf = (gdb_byte *) xmalloc (TYPE_LENGTH (baseclass));
542 back_to = make_cleanup (xfree, buf);
544 if (target_read_memory (address + boffset, buf,
545 TYPE_LENGTH (baseclass)) != 0)
547 base_val = value_from_contents_and_address (baseclass,
550 baseclass = value_type (base_val);
553 thistype = baseclass;
554 base_valaddr = value_contents_for_printing_const (base_val);
555 do_cleanups (back_to);
559 base_valaddr = valaddr;
565 base_valaddr = valaddr;
570 /* Now do the printing. */
571 if (options->prettyformat)
573 fprintf_filtered (stream, "\n");
574 print_spaces_filtered (2 * recurse, stream);
576 fputs_filtered ("<", stream);
577 /* Not sure what the best notation is in the case where there is
578 no baseclass name. */
579 fputs_filtered (basename ? basename : "", stream);
580 fputs_filtered ("> = ", stream);
583 val_print_unavailable (stream);
585 val_print_invalid_address (stream);
590 /* Attempt to run an extension language pretty-printer on the
591 baseclass if possible. */
594 = apply_ext_lang_val_pretty_printer (baseclass, base_valaddr,
595 thisoffset + boffset,
596 value_address (base_val),
602 cp_print_value_fields (baseclass, thistype,
603 thisoffset + boffset,
604 value_address (base_val),
605 stream, recurse, base_val, options,
607 obstack_base (&dont_print_vb_obstack)),
610 fputs_filtered (", ", stream);
616 if (dont_print_vb == 0)
618 /* Free the space used to deal with the printing
619 of this type from top level. */
620 obstack_free (&dont_print_vb_obstack, last_dont_print);
621 /* Reset watermark so that we can continue protecting
622 ourselves from whatever we were protecting ourselves. */
623 dont_print_vb_obstack = tmp_obstack;
627 /* Print value of a static member. To avoid infinite recursion when
628 printing a class that contains a static instance of the class, we
629 keep the addresses of all printed static member classes in an
630 obstack and refuse to print them more than once.
632 VAL contains the value to print, TYPE, STREAM, RECURSE, and OPTIONS
633 have the same meanings as in c_val_print. */
636 cp_print_static_field (struct type *type,
638 struct ui_file *stream,
640 const struct value_print_options *options)
642 struct value_print_options opts;
644 if (value_entirely_optimized_out (val))
646 val_print_optimized_out (val, stream);
650 if (TYPE_CODE (type) == TYPE_CODE_STRUCT)
652 CORE_ADDR *first_dont_print;
657 = (CORE_ADDR *) obstack_base (&dont_print_statmem_obstack);
658 i = obstack_object_size (&dont_print_statmem_obstack)
659 / sizeof (CORE_ADDR);
663 if (value_address (val) == first_dont_print[i])
665 fputs_filtered ("<same as static member of an already"
672 addr = value_address (val);
673 obstack_grow (&dont_print_statmem_obstack, (char *) &addr,
675 type = check_typedef (type);
676 cp_print_value_fields (type, value_enclosing_type (val),
677 value_embedded_offset (val), addr,
678 stream, recurse, val,
683 if (TYPE_CODE (type) == TYPE_CODE_ARRAY)
685 struct type **first_dont_print;
687 struct type *target_type = TYPE_TARGET_TYPE (type);
690 = (struct type **) obstack_base (&dont_print_stat_array_obstack);
691 i = obstack_object_size (&dont_print_stat_array_obstack)
692 / sizeof (struct type *);
696 if (target_type == first_dont_print[i])
698 fputs_filtered ("<same as static member of an already"
705 obstack_grow (&dont_print_stat_array_obstack,
706 (char *) &target_type,
707 sizeof (struct type *));
713 value_embedded_offset (val),
715 stream, recurse, val,
716 &opts, current_language);
719 /* Find the field in *SELF, or its non-virtual base classes, with
720 bit offset OFFSET. Set *SELF to the containing type and *FIELDNO
721 to the containing field number. If OFFSET is not exactly at the
722 start of some field, set *SELF to NULL. */
725 cp_find_class_member (struct type **self_p, int *fieldno,
732 *self_p = check_typedef (*self_p);
734 len = TYPE_NFIELDS (self);
736 for (i = TYPE_N_BASECLASSES (self); i < len; i++)
738 LONGEST bitpos = TYPE_FIELD_BITPOS (self, i);
741 if (offset == bitpos)
748 for (i = 0; i < TYPE_N_BASECLASSES (self); i++)
750 LONGEST bitpos = TYPE_FIELD_BITPOS (self, i);
751 LONGEST bitsize = 8 * TYPE_LENGTH (TYPE_FIELD_TYPE (self, i));
753 if (offset >= bitpos && offset < bitpos + bitsize)
755 *self_p = TYPE_FIELD_TYPE (self, i);
756 cp_find_class_member (self_p, fieldno, offset - bitpos);
765 cp_print_class_member (const gdb_byte *valaddr, struct type *type,
766 struct ui_file *stream, char *prefix)
768 enum bfd_endian byte_order = gdbarch_byte_order (get_type_arch (type));
770 /* VAL is a byte offset into the structure type SELF_TYPE.
771 Find the name of the field for that offset and
773 struct type *self_type = TYPE_SELF_TYPE (type);
777 val = extract_signed_integer (valaddr,
781 /* Pointers to data members are usually byte offsets into an object.
782 Because a data member can have offset zero, and a NULL pointer to
783 member must be distinct from any valid non-NULL pointer to
784 member, either the value is biased or the NULL value has a
785 special representation; both are permitted by ISO C++. HP aCC
786 used a bias of 0x20000000; HP cfront used a bias of 1; g++ 3.x
787 and other compilers which use the Itanium ABI use -1 as the NULL
788 value. GDB only supports that last form; to add support for
789 another form, make this into a cp-abi hook. */
793 fprintf_filtered (stream, "NULL");
797 cp_find_class_member (&self_type, &fieldno, val << 3);
799 if (self_type != NULL)
803 fputs_filtered (prefix, stream);
804 name = type_name_no_tag (self_type);
806 fputs_filtered (name, stream);
808 c_type_print_base (self_type, stream, 0, 0, &type_print_raw_options);
809 fprintf_filtered (stream, "::");
810 fputs_filtered (TYPE_FIELD_NAME (self_type, fieldno), stream);
813 fprintf_filtered (stream, "%ld", (long) val);
818 _initialize_cp_valprint (void)
820 add_setshow_boolean_cmd ("static-members", class_support,
821 &user_print_options.static_field_print, _("\
822 Set printing of C++ static members."), _("\
823 Show printing of C++ static members."), NULL,
825 show_static_field_print,
826 &setprintlist, &showprintlist);
828 add_setshow_boolean_cmd ("vtbl", class_support,
829 &user_print_options.vtblprint, _("\
830 Set printing of C++ virtual function tables."), _("\
831 Show printing of C++ virtual function tables."), NULL,
834 &setprintlist, &showprintlist);
836 add_setshow_boolean_cmd ("object", class_support,
837 &user_print_options.objectprint, _("\
838 Set printing of object's derived type based on vtable info."), _("\
839 Show printing of object's derived type based on vtable info."), NULL,
842 &setprintlist, &showprintlist);
844 obstack_begin (&dont_print_stat_array_obstack,
845 32 * sizeof (struct type *));
846 obstack_begin (&dont_print_statmem_obstack,
847 32 * sizeof (CORE_ADDR));
848 obstack_begin (&dont_print_vb_obstack,
849 32 * sizeof (struct type *));