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binutils-gdb/gdb/cp-valprint.c

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/* Support for printing C++ values for GDB, the GNU debugger.
Copyright (C) 1986, 1988, 1989, 1991, 1992, 1993, 1994, 1995, 1996, 1997,
2000, 2001, 2002, 2003, 2005, 2006, 2007, 2008, 2009
Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include "defs.h"
#include "gdb_obstack.h"
#include "symtab.h"
#include "gdbtypes.h"
#include "expression.h"
#include "value.h"
#include "command.h"
#include "gdbcmd.h"
#include "demangle.h"
#include "annotate.h"
#include "gdb_string.h"
#include "c-lang.h"
#include "target.h"
#include "cp-abi.h"
#include "valprint.h"
#include "cp-support.h"
#include "language.h"
#include "python/python.h"
/* Controls printing of vtbl's */
static void
show_vtblprint (struct ui_file *file, int from_tty,
struct cmd_list_element *c, const char *value)
{
fprintf_filtered (file, _("\
Printing of C++ virtual function tables is %s.\n"),
value);
}
/* Controls looking up an object's derived type using what we find in
its vtables. */
static void
show_objectprint (struct ui_file *file, int from_tty,
struct cmd_list_element *c,
const char *value)
{
fprintf_filtered (file, _("\
Printing of object's derived type based on vtable info is %s.\n"),
value);
}
static void
show_static_field_print (struct ui_file *file, int from_tty,
struct cmd_list_element *c, const char *value)
{
fprintf_filtered (file, _("Printing of C++ static members is %s.\n"),
value);
}
static struct obstack dont_print_vb_obstack;
static struct obstack dont_print_statmem_obstack;
extern void _initialize_cp_valprint (void);
static void cp_print_static_field (struct type *, struct value *,
struct ui_file *, int,
const struct value_print_options *);
static void cp_print_value (struct type *, struct type *, const gdb_byte *,
int, CORE_ADDR, struct ui_file *, int,
const struct value_print_options *, struct type **);
/* GCC versions after 2.4.5 use this. */
const char vtbl_ptr_name[] = "__vtbl_ptr_type";
/* Return truth value for assertion that TYPE is of the type
"pointer to virtual function". */
int
cp_is_vtbl_ptr_type (struct type *type)
{
char *typename = type_name_no_tag (type);
return (typename != NULL && !strcmp (typename, vtbl_ptr_name));
}
/* Return truth value for the assertion that TYPE is of the type
"pointer to virtual function table". */
int
cp_is_vtbl_member (struct type *type)
{
/* With older versions of g++, the vtbl field pointed to an array
of structures. Nowadays it points directly to the structure. */
if (TYPE_CODE (type) == TYPE_CODE_PTR)
{
type = TYPE_TARGET_TYPE (type);
if (TYPE_CODE (type) == TYPE_CODE_ARRAY)
{
type = TYPE_TARGET_TYPE (type);
if (TYPE_CODE (type) == TYPE_CODE_STRUCT /* if not using thunks */
|| TYPE_CODE (type) == TYPE_CODE_PTR) /* if using thunks */
{
/* Virtual functions tables are full of pointers
to virtual functions. */
return cp_is_vtbl_ptr_type (type);
}
}
else if (TYPE_CODE (type) == TYPE_CODE_STRUCT) /* if not using thunks */
{
return cp_is_vtbl_ptr_type (type);
}
else if (TYPE_CODE (type) == TYPE_CODE_PTR) /* if using thunks */
{
/* The type name of the thunk pointer is NULL when using dwarf2.
We could test for a pointer to a function, but there is
no type info for the virtual table either, so it wont help. */
return cp_is_vtbl_ptr_type (type);
}
}
return 0;
}
/* Mutually recursive subroutines of cp_print_value and c_val_print to
print out a structure's fields: cp_print_value_fields and cp_print_value.
TYPE, VALADDR, ADDRESS, STREAM, RECURSE, and OPTIONS have the
same meanings as in cp_print_value and c_val_print.
2nd argument REAL_TYPE is used to carry over the type of the derived
class across the recursion to base classes.
DONT_PRINT is an array of baseclass types that we
should not print, or zero if called from top level. */
void
cp_print_value_fields (struct type *type, struct type *real_type,
const gdb_byte *valaddr, int offset, CORE_ADDR address,
struct ui_file *stream, int recurse,
const struct value_print_options *options,
struct type **dont_print_vb, int dont_print_statmem)
{
int i, len, n_baseclasses;
char *last_dont_print = obstack_next_free (&dont_print_statmem_obstack);
int fields_seen = 0;
CHECK_TYPEDEF (type);
fprintf_filtered (stream, "{");
len = TYPE_NFIELDS (type);
n_baseclasses = TYPE_N_BASECLASSES (type);
/* First, print out baseclasses such that we don't print
duplicates of virtual baseclasses. */
if (n_baseclasses > 0)
cp_print_value (type, real_type, valaddr, offset, address, stream,
recurse + 1, options, dont_print_vb);
/* Second, print out data fields */
/* If there are no data fields, skip this part */
if (len == n_baseclasses || !len)
fprintf_filtered (stream, "<No data fields>");
else
{
struct obstack tmp_obstack = dont_print_statmem_obstack;
if (dont_print_statmem == 0)
{
/* If we're at top level, carve out a completely fresh
chunk of the obstack and use that until this particular
invocation returns. */
obstack_finish (&dont_print_statmem_obstack);
}
for (i = n_baseclasses; i < len; i++)
{
/* If requested, skip printing of static fields. */
if (!options->static_field_print
&& field_is_static (&TYPE_FIELD (type, i)))
continue;
if (fields_seen)
fprintf_filtered (stream, ", ");
else if (n_baseclasses > 0)
{
if (options->pretty)
{
fprintf_filtered (stream, "\n");
print_spaces_filtered (2 + 2 * recurse, stream);
fputs_filtered ("members of ", stream);
fputs_filtered (type_name_no_tag (type), stream);
fputs_filtered (": ", stream);
}
}
fields_seen = 1;
if (options->pretty)
{
fprintf_filtered (stream, "\n");
print_spaces_filtered (2 + 2 * recurse, stream);
}
else
{
wrap_here (n_spaces (2 + 2 * recurse));
}
if (options->inspect_it)
{
if (TYPE_CODE (TYPE_FIELD_TYPE (type, i)) == TYPE_CODE_PTR)
fputs_filtered ("\"( ptr \"", stream);
else
fputs_filtered ("\"( nodef \"", stream);
if (field_is_static (&TYPE_FIELD (type, i)))
fputs_filtered ("static ", stream);
fprintf_symbol_filtered (stream, TYPE_FIELD_NAME (type, i),
current_language->la_language,
DMGL_PARAMS | DMGL_ANSI);
fputs_filtered ("\" \"", stream);
fprintf_symbol_filtered (stream, TYPE_FIELD_NAME (type, i),
current_language->la_language,
DMGL_PARAMS | DMGL_ANSI);
fputs_filtered ("\") \"", stream);
}
else
{
annotate_field_begin (TYPE_FIELD_TYPE (type, i));
if (field_is_static (&TYPE_FIELD (type, i)))
fputs_filtered ("static ", stream);
fprintf_symbol_filtered (stream, TYPE_FIELD_NAME (type, i),
current_language->la_language,
DMGL_PARAMS | DMGL_ANSI);
annotate_field_name_end ();
/* do not print leading '=' in case of anonymous unions */
if (strcmp (TYPE_FIELD_NAME (type, i), ""))
fputs_filtered (" = ", stream);
annotate_field_value ();
}
if (!field_is_static (&TYPE_FIELD (type, i))
&& TYPE_FIELD_PACKED (type, i))
{
struct value *v;
/* Bitfields require special handling, especially due to byte
order problems. */
if (TYPE_FIELD_IGNORE (type, i))
{
fputs_filtered ("<optimized out or zero length>", stream);
}
else
{
struct value_print_options opts = *options;
opts.deref_ref = 0;
v = value_from_longest
(TYPE_FIELD_TYPE (type, i),
unpack_field_as_long (type, valaddr + offset, i));
common_val_print (v, stream, recurse + 1, &opts,
current_language);
}
}
else
{
if (TYPE_FIELD_IGNORE (type, i))
{
fputs_filtered ("<optimized out or zero length>", stream);
}
else if (field_is_static (&TYPE_FIELD (type, i)))
{
struct value *v = value_static_field (type, i);
if (v == NULL)
fputs_filtered ("<optimized out>", stream);
else
cp_print_static_field (TYPE_FIELD_TYPE (type, i), v,
stream, recurse + 1, options);
}
else
{
struct value_print_options opts = *options;
opts.deref_ref = 0;
val_print (TYPE_FIELD_TYPE (type, i),
valaddr, offset + TYPE_FIELD_BITPOS (type, i) / 8,
address + TYPE_FIELD_BITPOS (type, i) / 8,
stream, recurse + 1, &opts,
current_language);
}
}
annotate_field_end ();
}
if (dont_print_statmem == 0)
{
/* Free the space used to deal with the printing
of the members from top level. */
obstack_free (&dont_print_statmem_obstack, last_dont_print);
dont_print_statmem_obstack = tmp_obstack;
}
if (options->pretty)
{
fprintf_filtered (stream, "\n");
print_spaces_filtered (2 * recurse, stream);
}
} /* if there are data fields */
fprintf_filtered (stream, "}");
}
/* Special val_print routine to avoid printing multiple copies of virtual
baseclasses. */
static void
cp_print_value (struct type *type, struct type *real_type,
const gdb_byte *valaddr, int offset, CORE_ADDR address,
struct ui_file *stream, int recurse,
const struct value_print_options *options,
struct type **dont_print_vb)
{
struct type **last_dont_print
= (struct type **) obstack_next_free (&dont_print_vb_obstack);
struct obstack tmp_obstack = dont_print_vb_obstack;
int i, n_baseclasses = TYPE_N_BASECLASSES (type);
int thisoffset;
struct type *thistype;
if (dont_print_vb == 0)
{
/* If we're at top level, carve out a completely fresh
chunk of the obstack and use that until this particular
invocation returns. */
/* Bump up the high-water mark. Now alpha is omega. */
obstack_finish (&dont_print_vb_obstack);
}
for (i = 0; i < n_baseclasses; i++)
{
int boffset;
int skip;
struct type *baseclass = check_typedef (TYPE_BASECLASS (type, i));
char *basename = TYPE_NAME (baseclass);
const gdb_byte *base_valaddr;
if (BASETYPE_VIA_VIRTUAL (type, i))
{
struct type **first_dont_print
= (struct type **) obstack_base (&dont_print_vb_obstack);
int j = (struct type **) obstack_next_free (&dont_print_vb_obstack)
- first_dont_print;
while (--j >= 0)
if (baseclass == first_dont_print[j])
goto flush_it;
obstack_ptr_grow (&dont_print_vb_obstack, baseclass);
}
thisoffset = offset;
thistype = real_type;
boffset = baseclass_offset (type, i, valaddr + offset, address);
skip = ((boffset == -1) || (boffset + offset) < 0) ? 1 : -1;
if (BASETYPE_VIA_VIRTUAL (type, i))
{
/* The virtual base class pointer might have been
clobbered by the user program. Make sure that it
still points to a valid memory location. */
if (boffset != -1
&& ((boffset + offset) < 0
|| (boffset + offset) >= TYPE_LENGTH (type)))
{
/* FIXME (alloca): unsafe if baseclass is really really large. */
gdb_byte *buf = alloca (TYPE_LENGTH (baseclass));
base_valaddr = buf;
if (target_read_memory (address + boffset, buf,
TYPE_LENGTH (baseclass)) != 0)
skip = 1;
address = address + boffset;
thisoffset = 0;
boffset = 0;
thistype = baseclass;
}
else
base_valaddr = valaddr;
}
else
base_valaddr = valaddr;
/* now do the printing */
if (options->pretty)
{
fprintf_filtered (stream, "\n");
print_spaces_filtered (2 * recurse, stream);
}
fputs_filtered ("<", stream);
/* Not sure what the best notation is in the case where there is no
baseclass name. */
fputs_filtered (basename ? basename : "", stream);
fputs_filtered ("> = ", stream);
if (skip >= 1)
fprintf_filtered (stream, "<invalid address>");
else
{
int result = 0;
/* Attempt to run the Python pretty-printers on the
baseclass if possible. */
if (!options->raw)
result = apply_val_pretty_printer (baseclass, base_valaddr,
thisoffset + boffset,
address + boffset,
stream, recurse,
options,
current_language);
if (!result)
cp_print_value_fields (baseclass, thistype, base_valaddr,
thisoffset + boffset, address + boffset,
stream, recurse, options,
((struct type **)
obstack_base (&dont_print_vb_obstack)),
0);
}
fputs_filtered (", ", stream);
flush_it:
;
}
if (dont_print_vb == 0)
{
/* Free the space used to deal with the printing
of this type from top level. */
obstack_free (&dont_print_vb_obstack, last_dont_print);
/* Reset watermark so that we can continue protecting
ourselves from whatever we were protecting ourselves. */
dont_print_vb_obstack = tmp_obstack;
}
}
/* Print value of a static member.
To avoid infinite recursion when printing a class that contains
a static instance of the class, we keep the addresses of all printed
static member classes in an obstack and refuse to print them more
than once.
VAL contains the value to print, TYPE, STREAM, RECURSE, and OPTIONS
have the same meanings as in c_val_print. */
static void
cp_print_static_field (struct type *type,
struct value *val,
struct ui_file *stream,
int recurse,
const struct value_print_options *options)
{
struct value_print_options opts;
if (TYPE_CODE (type) == TYPE_CODE_STRUCT)
{
CORE_ADDR *first_dont_print;
CORE_ADDR addr;
int i;
first_dont_print
= (CORE_ADDR *) obstack_base (&dont_print_statmem_obstack);
i = (CORE_ADDR *) obstack_next_free (&dont_print_statmem_obstack)
- first_dont_print;
while (--i >= 0)
{
if (value_address (val) == first_dont_print[i])
{
fputs_filtered ("<same as static member of an already"
" seen type>",
stream);
return;
}
}
addr = value_address (val);
obstack_grow (&dont_print_statmem_obstack, (char *) &addr,
sizeof (CORE_ADDR));
CHECK_TYPEDEF (type);
cp_print_value_fields (type, type, value_contents_all (val),
value_embedded_offset (val), addr,
stream, recurse, options, NULL, 1);
return;
}
opts = *options;
opts.deref_ref = 0;
val_print (type, value_contents_all (val),
value_embedded_offset (val), value_address (val),
stream, recurse, &opts, current_language);
}
/* Find the field in *DOMAIN, or its non-virtual base classes, with bit offset
OFFSET. Set *DOMAIN to the containing type and *FIELDNO to the containing
field number. If OFFSET is not exactly at the start of some field, set
*DOMAIN to NULL. */
static void
cp_find_class_member (struct type **domain_p, int *fieldno,
LONGEST offset)
{
struct type *domain;
unsigned int i;
unsigned len;
*domain_p = check_typedef (*domain_p);
domain = *domain_p;
len = TYPE_NFIELDS (domain);
for (i = TYPE_N_BASECLASSES (domain); i < len; i++)
{
LONGEST bitpos = TYPE_FIELD_BITPOS (domain, i);
QUIT;
if (offset == bitpos)
{
*fieldno = i;
return;
}
}
for (i = 0; i < TYPE_N_BASECLASSES (domain); i++)
{
LONGEST bitpos = TYPE_FIELD_BITPOS (domain, i);
LONGEST bitsize = 8 * TYPE_LENGTH (TYPE_FIELD_TYPE (domain, i));
if (offset >= bitpos && offset < bitpos + bitsize)
{
*domain_p = TYPE_FIELD_TYPE (domain, i);
cp_find_class_member (domain_p, fieldno, offset - bitpos);
return;
}
}
*domain_p = NULL;
}
void
cp_print_class_member (const gdb_byte *valaddr, struct type *type,
struct ui_file *stream, char *prefix)
{
/* VAL is a byte offset into the structure type DOMAIN.
Find the name of the field for that offset and
print it. */
struct type *domain = TYPE_DOMAIN_TYPE (type);
LONGEST val = extract_signed_integer (valaddr, TYPE_LENGTH (type));
unsigned int fieldno;
/* Pointers to data members are usually byte offsets into an object.
Because a data member can have offset zero, and a NULL pointer to
member must be distinct from any valid non-NULL pointer to
member, either the value is biased or the NULL value has a
special representation; both are permitted by ISO C++. HP aCC
used a bias of 0x20000000; HP cfront used a bias of 1; g++ 3.x
and other compilers which use the Itanium ABI use -1 as the NULL
value. GDB only supports that last form; to add support for
another form, make this into a cp-abi hook. */
if (val == -1)
{
fprintf_filtered (stream, "NULL");
return;
}
cp_find_class_member (&domain, &fieldno, val << 3);
if (domain != NULL)
{
char *name;
fputs_filtered (prefix, stream);
name = type_name_no_tag (domain);
if (name)
fputs_filtered (name, stream);
else
c_type_print_base (domain, stream, 0, 0);
fprintf_filtered (stream, "::");
fputs_filtered (TYPE_FIELD_NAME (domain, fieldno), stream);
}
else
fprintf_filtered (stream, "%ld", (long) val);
}
void
_initialize_cp_valprint (void)
{
add_setshow_boolean_cmd ("static-members", class_support,
&user_print_options.static_field_print, _("\
Set printing of C++ static members."), _("\
Show printing of C++ static members."), NULL,
NULL,
show_static_field_print,
&setprintlist, &showprintlist);
add_setshow_boolean_cmd ("vtbl", class_support,
&user_print_options.vtblprint, _("\
Set printing of C++ virtual function tables."), _("\
Show printing of C++ virtual function tables."), NULL,
NULL,
show_vtblprint,
&setprintlist, &showprintlist);
add_setshow_boolean_cmd ("object", class_support,
&user_print_options.objectprint, _("\
Set printing of object's derived type based on vtable info."), _("\
Show printing of object's derived type based on vtable info."), NULL,
NULL,
show_objectprint,
&setprintlist, &showprintlist);
obstack_begin (&dont_print_vb_obstack, 32 * sizeof (struct type *));
obstack_specify_allocation (&dont_print_statmem_obstack,
32 * sizeof (CORE_ADDR), sizeof (CORE_ADDR),
xmalloc, xfree);
}
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