447 lines
16 KiB
C
447 lines
16 KiB
C
/* Abstraction of GNU v3 abi.
|
|
Contributed by Jim Blandy <jimb@redhat.com>
|
|
|
|
Copyright 2001, 2002, 2003, 2005 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 2 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, write to the Free Software
|
|
Foundation, Inc., 59 Temple Place - Suite 330,
|
|
Boston, MA 02111-1307, USA. */
|
|
|
|
#include "defs.h"
|
|
#include "value.h"
|
|
#include "cp-abi.h"
|
|
#include "cp-support.h"
|
|
#include "demangle.h"
|
|
#include "gdb_assert.h"
|
|
#include "gdb_string.h"
|
|
|
|
static struct cp_abi_ops gnu_v3_abi_ops;
|
|
|
|
static int
|
|
gnuv3_is_vtable_name (const char *name)
|
|
{
|
|
return strncmp (name, "_ZTV", 4) == 0;
|
|
}
|
|
|
|
static int
|
|
gnuv3_is_operator_name (const char *name)
|
|
{
|
|
return strncmp (name, "operator", 8) == 0;
|
|
}
|
|
|
|
|
|
/* To help us find the components of a vtable, we build ourselves a
|
|
GDB type object representing the vtable structure. Following the
|
|
V3 ABI, it goes something like this:
|
|
|
|
struct gdb_gnu_v3_abi_vtable {
|
|
|
|
/ * An array of virtual call and virtual base offsets. The real
|
|
length of this array depends on the class hierarchy; we use
|
|
negative subscripts to access the elements. Yucky, but
|
|
better than the alternatives. * /
|
|
ptrdiff_t vcall_and_vbase_offsets[0];
|
|
|
|
/ * The offset from a virtual pointer referring to this table
|
|
to the top of the complete object. * /
|
|
ptrdiff_t offset_to_top;
|
|
|
|
/ * The type_info pointer for this class. This is really a
|
|
std::type_info *, but GDB doesn't really look at the
|
|
type_info object itself, so we don't bother to get the type
|
|
exactly right. * /
|
|
void *type_info;
|
|
|
|
/ * Virtual table pointers in objects point here. * /
|
|
|
|
/ * Virtual function pointers. Like the vcall/vbase array, the
|
|
real length of this table depends on the class hierarchy. * /
|
|
void (*virtual_functions[0]) ();
|
|
|
|
};
|
|
|
|
The catch, of course, is that the exact layout of this table
|
|
depends on the ABI --- word size, endianness, alignment, etc. So
|
|
the GDB type object is actually a per-architecture kind of thing.
|
|
|
|
vtable_type_gdbarch_data is a gdbarch per-architecture data pointer
|
|
which refers to the struct type * for this structure, laid out
|
|
appropriately for the architecture. */
|
|
static struct gdbarch_data *vtable_type_gdbarch_data;
|
|
|
|
|
|
/* Human-readable names for the numbers of the fields above. */
|
|
enum {
|
|
vtable_field_vcall_and_vbase_offsets,
|
|
vtable_field_offset_to_top,
|
|
vtable_field_type_info,
|
|
vtable_field_virtual_functions
|
|
};
|
|
|
|
|
|
/* Return a GDB type representing `struct gdb_gnu_v3_abi_vtable',
|
|
described above, laid out appropriately for ARCH.
|
|
|
|
We use this function as the gdbarch per-architecture data
|
|
initialization function. We assume that the gdbarch framework
|
|
calls the per-architecture data initialization functions after it
|
|
sets current_gdbarch to the new architecture. */
|
|
static void *
|
|
build_gdb_vtable_type (struct gdbarch *arch)
|
|
{
|
|
struct type *t;
|
|
struct field *field_list, *field;
|
|
int offset;
|
|
|
|
struct type *void_ptr_type
|
|
= lookup_pointer_type (builtin_type_void);
|
|
struct type *ptr_to_void_fn_type
|
|
= lookup_pointer_type (lookup_function_type (builtin_type_void));
|
|
|
|
/* ARCH can't give us the true ptrdiff_t type, so we guess. */
|
|
struct type *ptrdiff_type
|
|
= init_type (TYPE_CODE_INT, TARGET_PTR_BIT / TARGET_CHAR_BIT, 0,
|
|
"ptrdiff_t", 0);
|
|
|
|
/* We assume no padding is necessary, since GDB doesn't know
|
|
anything about alignment at the moment. If this assumption bites
|
|
us, we should add a gdbarch method which, given a type, returns
|
|
the alignment that type requires, and then use that here. */
|
|
|
|
/* Build the field list. */
|
|
field_list = xmalloc (sizeof (struct field [4]));
|
|
memset (field_list, 0, sizeof (struct field [4]));
|
|
field = &field_list[0];
|
|
offset = 0;
|
|
|
|
/* ptrdiff_t vcall_and_vbase_offsets[0]; */
|
|
FIELD_NAME (*field) = "vcall_and_vbase_offsets";
|
|
FIELD_TYPE (*field)
|
|
= create_array_type (0, ptrdiff_type,
|
|
create_range_type (0, builtin_type_int, 0, -1));
|
|
FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT;
|
|
offset += TYPE_LENGTH (FIELD_TYPE (*field));
|
|
field++;
|
|
|
|
/* ptrdiff_t offset_to_top; */
|
|
FIELD_NAME (*field) = "offset_to_top";
|
|
FIELD_TYPE (*field) = ptrdiff_type;
|
|
FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT;
|
|
offset += TYPE_LENGTH (FIELD_TYPE (*field));
|
|
field++;
|
|
|
|
/* void *type_info; */
|
|
FIELD_NAME (*field) = "type_info";
|
|
FIELD_TYPE (*field) = void_ptr_type;
|
|
FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT;
|
|
offset += TYPE_LENGTH (FIELD_TYPE (*field));
|
|
field++;
|
|
|
|
/* void (*virtual_functions[0]) (); */
|
|
FIELD_NAME (*field) = "virtual_functions";
|
|
FIELD_TYPE (*field)
|
|
= create_array_type (0, ptr_to_void_fn_type,
|
|
create_range_type (0, builtin_type_int, 0, -1));
|
|
FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT;
|
|
offset += TYPE_LENGTH (FIELD_TYPE (*field));
|
|
field++;
|
|
|
|
/* We assumed in the allocation above that there were four fields. */
|
|
gdb_assert (field == (field_list + 4));
|
|
|
|
t = init_type (TYPE_CODE_STRUCT, offset, 0, 0, 0);
|
|
TYPE_NFIELDS (t) = field - field_list;
|
|
TYPE_FIELDS (t) = field_list;
|
|
TYPE_TAG_NAME (t) = "gdb_gnu_v3_abi_vtable";
|
|
|
|
return t;
|
|
}
|
|
|
|
|
|
/* Return the offset from the start of the imaginary `struct
|
|
gdb_gnu_v3_abi_vtable' object to the vtable's "address point"
|
|
(i.e., where objects' virtual table pointers point). */
|
|
static int
|
|
vtable_address_point_offset (void)
|
|
{
|
|
struct type *vtable_type = gdbarch_data (current_gdbarch,
|
|
vtable_type_gdbarch_data);
|
|
|
|
return (TYPE_FIELD_BITPOS (vtable_type, vtable_field_virtual_functions)
|
|
/ TARGET_CHAR_BIT);
|
|
}
|
|
|
|
|
|
static struct type *
|
|
gnuv3_rtti_type (struct value *value,
|
|
int *full_p, int *top_p, int *using_enc_p)
|
|
{
|
|
struct type *vtable_type = gdbarch_data (current_gdbarch,
|
|
vtable_type_gdbarch_data);
|
|
struct type *values_type = check_typedef (value_type (value));
|
|
CORE_ADDR vtable_address;
|
|
struct value *vtable;
|
|
struct minimal_symbol *vtable_symbol;
|
|
const char *vtable_symbol_name;
|
|
const char *class_name;
|
|
struct type *run_time_type;
|
|
struct type *base_type;
|
|
LONGEST offset_to_top;
|
|
|
|
/* We only have RTTI for class objects. */
|
|
if (TYPE_CODE (values_type) != TYPE_CODE_CLASS)
|
|
return NULL;
|
|
|
|
/* If we can't find the virtual table pointer for values_type, we
|
|
can't find the RTTI. */
|
|
fill_in_vptr_fieldno (values_type);
|
|
if (TYPE_VPTR_FIELDNO (values_type) == -1)
|
|
return NULL;
|
|
|
|
if (using_enc_p)
|
|
*using_enc_p = 0;
|
|
|
|
/* Fetch VALUE's virtual table pointer, and tweak it to point at
|
|
an instance of our imaginary gdb_gnu_v3_abi_vtable structure. */
|
|
base_type = check_typedef (TYPE_VPTR_BASETYPE (values_type));
|
|
if (values_type != base_type)
|
|
{
|
|
value = value_cast (base_type, value);
|
|
if (using_enc_p)
|
|
*using_enc_p = 1;
|
|
}
|
|
vtable_address
|
|
= value_as_address (value_field (value, TYPE_VPTR_FIELDNO (values_type)));
|
|
vtable = value_at_lazy (vtable_type,
|
|
vtable_address - vtable_address_point_offset ());
|
|
|
|
/* Find the linker symbol for this vtable. */
|
|
vtable_symbol
|
|
= lookup_minimal_symbol_by_pc (VALUE_ADDRESS (vtable)
|
|
+ value_offset (vtable)
|
|
+ value_embedded_offset (vtable));
|
|
if (! vtable_symbol)
|
|
return NULL;
|
|
|
|
/* The symbol's demangled name should be something like "vtable for
|
|
CLASS", where CLASS is the name of the run-time type of VALUE.
|
|
If we didn't like this approach, we could instead look in the
|
|
type_info object itself to get the class name. But this way
|
|
should work just as well, and doesn't read target memory. */
|
|
vtable_symbol_name = SYMBOL_DEMANGLED_NAME (vtable_symbol);
|
|
if (vtable_symbol_name == NULL
|
|
|| strncmp (vtable_symbol_name, "vtable for ", 11))
|
|
{
|
|
warning (_("can't find linker symbol for virtual table for `%s' value"),
|
|
TYPE_NAME (values_type));
|
|
if (vtable_symbol_name)
|
|
warning (_(" found `%s' instead"), vtable_symbol_name);
|
|
return NULL;
|
|
}
|
|
class_name = vtable_symbol_name + 11;
|
|
|
|
/* Try to look up the class name as a type name. */
|
|
/* FIXME: chastain/2003-11-26: block=NULL is bogus. See pr gdb/1465. */
|
|
run_time_type = cp_lookup_rtti_type (class_name, NULL);
|
|
if (run_time_type == NULL)
|
|
return NULL;
|
|
|
|
/* Get the offset from VALUE to the top of the complete object.
|
|
NOTE: this is the reverse of the meaning of *TOP_P. */
|
|
offset_to_top
|
|
= value_as_long (value_field (vtable, vtable_field_offset_to_top));
|
|
|
|
if (full_p)
|
|
*full_p = (- offset_to_top == value_embedded_offset (value)
|
|
&& (TYPE_LENGTH (value_enclosing_type (value))
|
|
>= TYPE_LENGTH (run_time_type)));
|
|
if (top_p)
|
|
*top_p = - offset_to_top;
|
|
|
|
return run_time_type;
|
|
}
|
|
|
|
|
|
static struct value *
|
|
gnuv3_virtual_fn_field (struct value **value_p,
|
|
struct fn_field *f, int j,
|
|
struct type *type, int offset)
|
|
{
|
|
struct type *vtable_type = gdbarch_data (current_gdbarch,
|
|
vtable_type_gdbarch_data);
|
|
struct value *value = *value_p;
|
|
struct type *values_type = check_typedef (value_type (value));
|
|
struct type *vfn_base;
|
|
CORE_ADDR vtable_address;
|
|
struct value *vtable;
|
|
struct value *vfn;
|
|
|
|
/* Some simple sanity checks. */
|
|
if (TYPE_CODE (values_type) != TYPE_CODE_CLASS)
|
|
error (_("Only classes can have virtual functions."));
|
|
|
|
/* Find the base class that defines this virtual function. */
|
|
vfn_base = TYPE_FN_FIELD_FCONTEXT (f, j);
|
|
if (! vfn_base)
|
|
/* In programs compiled with G++ version 1, the debug info doesn't
|
|
say which base class defined the virtual function. We'll guess
|
|
it's the same base class that has our vtable; this is wrong for
|
|
multiple inheritance, but it's better than nothing. */
|
|
vfn_base = TYPE_VPTR_BASETYPE (type);
|
|
|
|
/* This type may have been defined before its virtual function table
|
|
was. If so, fill in the virtual function table entry for the
|
|
type now. */
|
|
if (TYPE_VPTR_FIELDNO (vfn_base) < 0)
|
|
fill_in_vptr_fieldno (vfn_base);
|
|
if (TYPE_VPTR_FIELDNO (vfn_base) < 0)
|
|
error (_("Could not find virtual table pointer for class \"%s\"."),
|
|
TYPE_TAG_NAME (vfn_base) ? TYPE_TAG_NAME (vfn_base) : "<unknown>");
|
|
|
|
/* Now that we know which base class is defining our virtual
|
|
function, cast our value to that baseclass. This takes care of
|
|
any necessary `this' adjustments. */
|
|
if (vfn_base != values_type)
|
|
value = value_cast (vfn_base, value);
|
|
|
|
/* Now value is an object of the appropriate base type. Fetch its
|
|
virtual table. */
|
|
/* It might be possible to do this cast at the same time as the above.
|
|
Does multiple inheritance affect this?
|
|
Can this even trigger, or is TYPE_VPTR_BASETYPE idempotent?
|
|
*/
|
|
if (TYPE_VPTR_BASETYPE (vfn_base) != vfn_base)
|
|
value = value_cast (TYPE_VPTR_BASETYPE (vfn_base), value);
|
|
vtable_address
|
|
= value_as_address (value_field (value, TYPE_VPTR_FIELDNO (vfn_base)));
|
|
|
|
vtable = value_at_lazy (vtable_type,
|
|
vtable_address - vtable_address_point_offset ());
|
|
|
|
/* Fetch the appropriate function pointer from the vtable. */
|
|
vfn = value_subscript (value_field (vtable, vtable_field_virtual_functions),
|
|
value_from_longest (builtin_type_int,
|
|
TYPE_FN_FIELD_VOFFSET (f, j)));
|
|
|
|
/* Cast the function pointer to the appropriate type. */
|
|
vfn = value_cast (lookup_pointer_type (TYPE_FN_FIELD_TYPE (f, j)),
|
|
vfn);
|
|
|
|
/* Is (type)value always numerically the same as (vfn_base)value?
|
|
If so we can spare this cast and use one of the ones above. */
|
|
*value_p = value_addr (value_cast (type, *value_p));
|
|
|
|
return vfn;
|
|
}
|
|
|
|
/* Compute the offset of the baseclass which is
|
|
the INDEXth baseclass of class TYPE,
|
|
for value at VALADDR (in host) at ADDRESS (in target).
|
|
The result is the offset of the baseclass value relative
|
|
to (the address of)(ARG) + OFFSET.
|
|
|
|
-1 is returned on error. */
|
|
static int
|
|
gnuv3_baseclass_offset (struct type *type, int index, const bfd_byte *valaddr,
|
|
CORE_ADDR address)
|
|
{
|
|
struct type *vtable_type = gdbarch_data (current_gdbarch,
|
|
vtable_type_gdbarch_data);
|
|
struct value *vtable;
|
|
struct type *vbasetype;
|
|
struct value *offset_val, *vbase_array;
|
|
CORE_ADDR vtable_address;
|
|
long int cur_base_offset, base_offset;
|
|
|
|
/* If it isn't a virtual base, this is easy. The offset is in the
|
|
type definition. */
|
|
if (!BASETYPE_VIA_VIRTUAL (type, index))
|
|
return TYPE_BASECLASS_BITPOS (type, index) / 8;
|
|
|
|
/* To access a virtual base, we need to use the vbase offset stored in
|
|
our vtable. Recent GCC versions provide this information. If it isn't
|
|
available, we could get what we needed from RTTI, or from drawing the
|
|
complete inheritance graph based on the debug info. Neither is
|
|
worthwhile. */
|
|
cur_base_offset = TYPE_BASECLASS_BITPOS (type, index) / 8;
|
|
if (cur_base_offset >= - vtable_address_point_offset ())
|
|
error (_("Expected a negative vbase offset (old compiler?)"));
|
|
|
|
cur_base_offset = cur_base_offset + vtable_address_point_offset ();
|
|
if ((- cur_base_offset) % TYPE_LENGTH (builtin_type_void_data_ptr) != 0)
|
|
error (_("Misaligned vbase offset."));
|
|
cur_base_offset = cur_base_offset
|
|
/ ((int) TYPE_LENGTH (builtin_type_void_data_ptr));
|
|
|
|
/* We're now looking for the cur_base_offset'th entry (negative index)
|
|
in the vcall_and_vbase_offsets array. We used to cast the object to
|
|
its TYPE_VPTR_BASETYPE, and reference the vtable as TYPE_VPTR_FIELDNO;
|
|
however, that cast can not be done without calling baseclass_offset again
|
|
if the TYPE_VPTR_BASETYPE is a virtual base class, as described in the
|
|
v3 C++ ABI Section 2.4.I.2.b. Fortunately the ABI guarantees that the
|
|
vtable pointer will be located at the beginning of the object, so we can
|
|
bypass the casting. Verify that the TYPE_VPTR_FIELDNO is in fact at the
|
|
start of whichever baseclass it resides in, as a sanity measure - iff
|
|
we have debugging information for that baseclass. */
|
|
|
|
vbasetype = TYPE_VPTR_BASETYPE (type);
|
|
if (TYPE_VPTR_FIELDNO (vbasetype) < 0)
|
|
fill_in_vptr_fieldno (vbasetype);
|
|
|
|
if (TYPE_VPTR_FIELDNO (vbasetype) >= 0
|
|
&& TYPE_FIELD_BITPOS (vbasetype, TYPE_VPTR_FIELDNO (vbasetype)) != 0)
|
|
error (_("Illegal vptr offset in class %s"),
|
|
TYPE_NAME (vbasetype) ? TYPE_NAME (vbasetype) : "<unknown>");
|
|
|
|
vtable_address = value_as_address (value_at_lazy (builtin_type_void_data_ptr,
|
|
address));
|
|
vtable = value_at_lazy (vtable_type,
|
|
vtable_address - vtable_address_point_offset ());
|
|
offset_val = value_from_longest(builtin_type_int, cur_base_offset);
|
|
vbase_array = value_field (vtable, vtable_field_vcall_and_vbase_offsets);
|
|
base_offset = value_as_long (value_subscript (vbase_array, offset_val));
|
|
return base_offset;
|
|
}
|
|
|
|
static void
|
|
init_gnuv3_ops (void)
|
|
{
|
|
vtable_type_gdbarch_data = gdbarch_data_register_post_init (build_gdb_vtable_type);
|
|
|
|
gnu_v3_abi_ops.shortname = "gnu-v3";
|
|
gnu_v3_abi_ops.longname = "GNU G++ Version 3 ABI";
|
|
gnu_v3_abi_ops.doc = "G++ Version 3 ABI";
|
|
gnu_v3_abi_ops.is_destructor_name =
|
|
(enum dtor_kinds (*) (const char *))is_gnu_v3_mangled_dtor;
|
|
gnu_v3_abi_ops.is_constructor_name =
|
|
(enum ctor_kinds (*) (const char *))is_gnu_v3_mangled_ctor;
|
|
gnu_v3_abi_ops.is_vtable_name = gnuv3_is_vtable_name;
|
|
gnu_v3_abi_ops.is_operator_name = gnuv3_is_operator_name;
|
|
gnu_v3_abi_ops.rtti_type = gnuv3_rtti_type;
|
|
gnu_v3_abi_ops.virtual_fn_field = gnuv3_virtual_fn_field;
|
|
gnu_v3_abi_ops.baseclass_offset = gnuv3_baseclass_offset;
|
|
}
|
|
|
|
extern initialize_file_ftype _initialize_gnu_v3_abi; /* -Wmissing-prototypes */
|
|
|
|
void
|
|
_initialize_gnu_v3_abi (void)
|
|
{
|
|
init_gnuv3_ops ();
|
|
|
|
register_cp_abi (&gnu_v3_abi_ops);
|
|
}
|