1 /* Support for printing C++ values for GDB, the GNU debugger.
3 Copyright (C) 1986-2014 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 "exceptions.h"
38 #include "typeprint.h"
40 /* Controls printing of vtbl's. */
42 show_vtblprint (struct ui_file *file, int from_tty,
43 struct cmd_list_element *c, const char *value)
45 fprintf_filtered (file, _("\
46 Printing of C++ virtual function tables is %s.\n"),
50 /* Controls looking up an object's derived type using what we find in
53 show_objectprint (struct ui_file *file, int from_tty,
54 struct cmd_list_element *c,
57 fprintf_filtered (file, _("\
58 Printing of object's derived type based on vtable info is %s.\n"),
63 show_static_field_print (struct ui_file *file, int from_tty,
64 struct cmd_list_element *c,
67 fprintf_filtered (file,
68 _("Printing of C++ static members is %s.\n"),
73 static struct obstack dont_print_vb_obstack;
74 static struct obstack dont_print_statmem_obstack;
75 static struct obstack dont_print_stat_array_obstack;
77 extern void _initialize_cp_valprint (void);
79 static void cp_print_static_field (struct type *, struct value *,
80 struct ui_file *, int,
81 const struct value_print_options *);
83 static void cp_print_value (struct type *, struct type *,
84 const gdb_byte *, int,
85 CORE_ADDR, struct ui_file *,
86 int, const struct value *,
87 const struct value_print_options *,
91 /* GCC versions after 2.4.5 use this. */
92 const char vtbl_ptr_name[] = "__vtbl_ptr_type";
94 /* Return truth value for assertion that TYPE is of the type
95 "pointer to virtual function". */
98 cp_is_vtbl_ptr_type (struct type *type)
100 const char *typename = type_name_no_tag (type);
102 return (typename != NULL && !strcmp (typename, vtbl_ptr_name));
105 /* Return truth value for the assertion that TYPE is of the type
106 "pointer to virtual function table". */
109 cp_is_vtbl_member (struct type *type)
111 /* With older versions of g++, the vtbl field pointed to an array of
112 structures. Nowadays it points directly to the structure. */
113 if (TYPE_CODE (type) == TYPE_CODE_PTR)
115 type = TYPE_TARGET_TYPE (type);
116 if (TYPE_CODE (type) == TYPE_CODE_ARRAY)
118 type = TYPE_TARGET_TYPE (type);
119 if (TYPE_CODE (type) == TYPE_CODE_STRUCT /* if not using thunks */
120 || TYPE_CODE (type) == TYPE_CODE_PTR) /* if using thunks */
122 /* Virtual functions tables are full of pointers
123 to virtual functions. */
124 return cp_is_vtbl_ptr_type (type);
127 else if (TYPE_CODE (type) == TYPE_CODE_STRUCT) /* if not using thunks */
129 return cp_is_vtbl_ptr_type (type);
131 else if (TYPE_CODE (type) == TYPE_CODE_PTR) /* if using thunks */
133 /* The type name of the thunk pointer is NULL when using
134 dwarf2. We could test for a pointer to a function, but
135 there is no type info for the virtual table either, so it
137 return cp_is_vtbl_ptr_type (type);
143 /* Mutually recursive subroutines of cp_print_value and c_val_print to
144 print out a structure's fields: cp_print_value_fields and
147 TYPE, VALADDR, ADDRESS, STREAM, RECURSE, and OPTIONS have the same
148 meanings as in cp_print_value and c_val_print.
150 2nd argument REAL_TYPE is used to carry over the type of the
151 derived class across the recursion to base classes.
153 DONT_PRINT is an array of baseclass types that we should not print,
154 or zero if called from top level. */
157 cp_print_value_fields (struct type *type, struct type *real_type,
158 const gdb_byte *valaddr, int offset,
159 CORE_ADDR address, struct ui_file *stream,
160 int recurse, const struct value *val,
161 const struct value_print_options *options,
162 struct type **dont_print_vb,
163 int dont_print_statmem)
165 int i, len, n_baseclasses;
167 static int last_set_recurse = -1;
169 CHECK_TYPEDEF (type);
173 /* Any object can be left on obstacks only during an unexpected
176 if (obstack_object_size (&dont_print_statmem_obstack) > 0)
178 obstack_free (&dont_print_statmem_obstack, NULL);
179 obstack_begin (&dont_print_statmem_obstack,
180 32 * sizeof (CORE_ADDR));
182 if (obstack_object_size (&dont_print_stat_array_obstack) > 0)
184 obstack_free (&dont_print_stat_array_obstack, NULL);
185 obstack_begin (&dont_print_stat_array_obstack,
186 32 * sizeof (struct type *));
190 fprintf_filtered (stream, "{");
191 len = TYPE_NFIELDS (type);
192 n_baseclasses = TYPE_N_BASECLASSES (type);
194 /* First, print out baseclasses such that we don't print
195 duplicates of virtual baseclasses. */
197 if (n_baseclasses > 0)
198 cp_print_value (type, real_type, valaddr,
199 offset, address, stream,
200 recurse + 1, val, options,
203 /* Second, print out data fields */
205 /* If there are no data fields, skip this part */
206 if (len == n_baseclasses || !len)
207 fprintf_filtered (stream, "<No data fields>");
210 size_t statmem_obstack_initial_size = 0;
211 size_t stat_array_obstack_initial_size = 0;
212 struct type *vptr_basetype = NULL;
215 if (dont_print_statmem == 0)
217 statmem_obstack_initial_size =
218 obstack_object_size (&dont_print_statmem_obstack);
220 if (last_set_recurse != recurse)
222 stat_array_obstack_initial_size =
223 obstack_object_size (&dont_print_stat_array_obstack);
225 last_set_recurse = recurse;
229 vptr_fieldno = get_vptr_fieldno (type, &vptr_basetype);
230 for (i = n_baseclasses; i < len; i++)
232 /* If requested, skip printing of static fields. */
233 if (!options->static_field_print
234 && field_is_static (&TYPE_FIELD (type, i)))
238 fprintf_filtered (stream, ", ");
239 else if (n_baseclasses > 0)
241 if (options->prettyformat)
243 fprintf_filtered (stream, "\n");
244 print_spaces_filtered (2 + 2 * recurse, stream);
245 fputs_filtered ("members of ", stream);
246 fputs_filtered (type_name_no_tag (type), stream);
247 fputs_filtered (": ", stream);
252 if (options->prettyformat)
254 fprintf_filtered (stream, "\n");
255 print_spaces_filtered (2 + 2 * recurse, stream);
259 wrap_here (n_spaces (2 + 2 * recurse));
262 annotate_field_begin (TYPE_FIELD_TYPE (type, i));
264 if (field_is_static (&TYPE_FIELD (type, i)))
265 fputs_filtered ("static ", stream);
266 fprintf_symbol_filtered (stream,
267 TYPE_FIELD_NAME (type, i),
268 current_language->la_language,
269 DMGL_PARAMS | DMGL_ANSI);
270 annotate_field_name_end ();
271 /* Do not print leading '=' in case of anonymous
273 if (strcmp (TYPE_FIELD_NAME (type, i), ""))
274 fputs_filtered (" = ", stream);
275 annotate_field_value ();
277 if (!field_is_static (&TYPE_FIELD (type, i))
278 && TYPE_FIELD_PACKED (type, i))
282 /* Bitfields require special handling, especially due to
283 byte order problems. */
284 if (TYPE_FIELD_IGNORE (type, i))
286 fputs_filtered ("<optimized out or zero length>", stream);
288 else if (value_bits_synthetic_pointer (val,
289 TYPE_FIELD_BITPOS (type,
291 TYPE_FIELD_BITSIZE (type,
294 fputs_filtered (_("<synthetic pointer>"), stream);
296 else if (!value_bits_valid (val,
297 TYPE_FIELD_BITPOS (type, i),
298 TYPE_FIELD_BITSIZE (type, i)))
300 val_print_optimized_out (val, stream);
304 struct value_print_options opts = *options;
308 v = value_field_bitfield (type, i, valaddr, offset, val);
310 common_val_print (v, stream, recurse + 1, &opts,
316 if (TYPE_FIELD_IGNORE (type, i))
318 fputs_filtered ("<optimized out or zero length>",
321 else if (field_is_static (&TYPE_FIELD (type, i)))
323 volatile struct gdb_exception ex;
324 struct value *v = NULL;
326 TRY_CATCH (ex, RETURN_MASK_ERROR)
328 v = value_static_field (type, i);
332 fprintf_filtered (stream,
333 _("<error reading variable: %s>"),
335 cp_print_static_field (TYPE_FIELD_TYPE (type, i),
336 v, stream, recurse + 1,
339 else if (i == vptr_fieldno && type == vptr_basetype)
341 int i_offset = offset + TYPE_FIELD_BITPOS (type, i) / 8;
342 struct type *i_type = TYPE_FIELD_TYPE (type, i);
344 if (valprint_check_validity (stream, i_type, i_offset, val))
348 addr = extract_typed_address (valaddr + i_offset, i_type);
349 print_function_pointer_address (options,
350 get_type_arch (type),
356 struct value_print_options opts = *options;
359 val_print (TYPE_FIELD_TYPE (type, i),
361 offset + TYPE_FIELD_BITPOS (type, i) / 8,
363 stream, recurse + 1, val, &opts,
367 annotate_field_end ();
370 if (dont_print_statmem == 0)
372 size_t obstack_final_size =
373 obstack_object_size (&dont_print_statmem_obstack);
375 if (obstack_final_size > statmem_obstack_initial_size)
377 /* In effect, a pop of the printed-statics stack. */
380 obstack_next_free (&dont_print_statmem_obstack) -
381 (obstack_final_size - statmem_obstack_initial_size);
383 obstack_free (&dont_print_statmem_obstack,
387 if (last_set_recurse != recurse)
389 size_t obstack_final_size =
390 obstack_object_size (&dont_print_stat_array_obstack);
392 if (obstack_final_size > stat_array_obstack_initial_size)
395 obstack_next_free (&dont_print_stat_array_obstack)
396 - (obstack_final_size
397 - stat_array_obstack_initial_size);
399 obstack_free (&dont_print_stat_array_obstack,
402 last_set_recurse = -1;
406 if (options->prettyformat)
408 fprintf_filtered (stream, "\n");
409 print_spaces_filtered (2 * recurse, stream);
411 } /* if there are data fields */
413 fprintf_filtered (stream, "}");
416 /* Like cp_print_value_fields, but find the runtime type of the object
417 and pass it as the `real_type' argument to cp_print_value_fields.
418 This function is a hack to work around the fact that
419 common_val_print passes the embedded offset to val_print, but not
420 the enclosing type. */
423 cp_print_value_fields_rtti (struct type *type,
424 const gdb_byte *valaddr, int offset,
426 struct ui_file *stream, int recurse,
427 const struct value *val,
428 const struct value_print_options *options,
429 struct type **dont_print_vb,
430 int dont_print_statmem)
432 struct type *real_type = NULL;
434 /* We require all bits to be valid in order to attempt a
436 if (value_bits_valid (val, TARGET_CHAR_BIT * offset,
437 TARGET_CHAR_BIT * TYPE_LENGTH (type)))
440 int full, top, using_enc;
442 /* Ugh, we have to convert back to a value here. */
443 value = value_from_contents_and_address (type, valaddr + offset,
445 type = value_type (value);
446 /* We don't actually care about most of the result here -- just
447 the type. We already have the correct offset, due to how
448 val_print was initially called. */
449 real_type = value_rtti_type (value, &full, &top, &using_enc);
455 cp_print_value_fields (type, real_type, valaddr, offset,
456 address, stream, recurse, val, options,
457 dont_print_vb, dont_print_statmem);
460 /* Special val_print routine to avoid printing multiple copies of
461 virtual baseclasses. */
464 cp_print_value (struct type *type, struct type *real_type,
465 const gdb_byte *valaddr, int offset,
466 CORE_ADDR address, struct ui_file *stream,
467 int recurse, const struct value *val,
468 const struct value_print_options *options,
469 struct type **dont_print_vb)
471 struct type **last_dont_print
472 = (struct type **) obstack_next_free (&dont_print_vb_obstack);
473 struct obstack tmp_obstack = dont_print_vb_obstack;
474 int i, n_baseclasses = TYPE_N_BASECLASSES (type);
476 struct type *thistype;
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 const struct value *base_val = NULL;
495 volatile struct gdb_exception ex;
497 if (BASETYPE_VIA_VIRTUAL (type, i))
499 struct type **first_dont_print
500 = (struct type **) obstack_base (&dont_print_vb_obstack);
502 int j = (struct type **)
503 obstack_next_free (&dont_print_vb_obstack) - first_dont_print;
506 if (baseclass == first_dont_print[j])
509 obstack_ptr_grow (&dont_print_vb_obstack, baseclass);
513 thistype = real_type;
515 TRY_CATCH (ex, RETURN_MASK_ERROR)
517 boffset = baseclass_offset (type, i, valaddr, offset, address, val);
519 if (ex.reason < 0 && ex.error == NOT_AVAILABLE_ERROR)
521 else if (ex.reason < 0)
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 = 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 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);
719 /* Find the field in *DOMAIN, or its non-virtual base classes, with
720 bit offset OFFSET. Set *DOMAIN 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 *DOMAIN to NULL. */
725 cp_find_class_member (struct type **domain_p, int *fieldno,
732 *domain_p = check_typedef (*domain_p);
734 len = TYPE_NFIELDS (domain);
736 for (i = TYPE_N_BASECLASSES (domain); i < len; i++)
738 LONGEST bitpos = TYPE_FIELD_BITPOS (domain, i);
741 if (offset == bitpos)
748 for (i = 0; i < TYPE_N_BASECLASSES (domain); i++)
750 LONGEST bitpos = TYPE_FIELD_BITPOS (domain, i);
751 LONGEST bitsize = 8 * TYPE_LENGTH (TYPE_FIELD_TYPE (domain, i));
753 if (offset >= bitpos && offset < bitpos + bitsize)
755 *domain_p = TYPE_FIELD_TYPE (domain, i);
756 cp_find_class_member (domain_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 DOMAIN.
771 Find the name of the field for that offset and
773 struct type *domain = TYPE_DOMAIN_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 (&domain, &fieldno, val << 3);
803 fputs_filtered (prefix, stream);
804 name = type_name_no_tag (domain);
806 fputs_filtered (name, stream);
808 c_type_print_base (domain, stream, 0, 0, &type_print_raw_options);
809 fprintf_filtered (stream, "::");
810 fputs_filtered (TYPE_FIELD_NAME (domain, 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 *));