static struct value *
gnuv3_get_vtable (struct gdbarch *gdbarch,
struct type *container_type, CORE_ADDR container_addr)
{
struct type *vtable_type = gdbarch_data (gdbarch,
vtable_type_gdbarch_data);
struct type *vtable_pointer_type;
struct value *vtable_pointer;
CORE_ADDR vtable_address;
/* If this type does not have a virtual table, don't read the first
field. */
if (!gnuv3_dynamic_class (check_typedef (container_type)))
return NULL;
/* We do not consult the debug information to find the virtual table.
The ABI specifies that it is always at offset zero in any class,
and debug information may not represent it.
We avoid using value_contents on principle, because the object might
be large. */
/* Find the type "pointer to virtual table". */
vtable_pointer_type = lookup_pointer_type (vtable_type);
/* Load it from the start of the class. */
vtable_pointer = value_at (vtable_pointer_type, container_addr);
vtable_address = value_as_address (vtable_pointer);
/* Correct it to point at the start of the virtual table, rather
than the address point. */
return value_at_lazy (vtable_type,
vtable_address
- vtable_address_point_offset (gdbarch));
}
static struct value *
gnuv3_get_vtable (struct gdbarch *gdbarch, struct value *container)
{
struct type *vtable_type = gdbarch_data (gdbarch, vtable_type_gdbarch_data);
struct type *vtable_pointer_type;
struct value *vtable_pointer;
CORE_ADDR vtable_pointer_address, vtable_address;
/* We do not consult the debug information to find the virtual table.
The ABI specifies that it is always at offset zero in any class,
and debug information may not represent it. We won't issue an
error if there's a class with virtual functions but no virtual table
pointer, but something's already gone seriously wrong if that
happens.
We avoid using value_contents on principle, because the object might
be large. */
/* Find the type "pointer to virtual table". */
vtable_pointer_type = lookup_pointer_type (vtable_type);
/* Load it from the start of the class. */
vtable_pointer_address = value_as_address (value_addr (container));
vtable_pointer = value_at (vtable_pointer_type, vtable_pointer_address);
vtable_address = value_as_address (vtable_pointer);
/* Correct it to point at the start of the virtual table, rather
than the address point. */
return value_at_lazy (vtable_type,
vtable_address - vtable_address_point_offset (gdbarch));
}
static int
gnuv3_baseclass_offset (struct type *type, int index,
const bfd_byte *valaddr, int embedded_offset,
CORE_ADDR address, const struct value *val)
{
struct gdbarch *gdbarch;
struct type *ptr_type;
struct value *vtable;
struct value *vbase_array;
long int cur_base_offset, base_offset;
/* Determine architecture. */
gdbarch = get_type_arch (type);
ptr_type = builtin_type (gdbarch)->builtin_data_ptr;
/* If it isn't a virtual base, this is easy. The offset is in the
type definition. Likewise for Java, which doesn't really have
virtual inheritance in the C++ sense. */
if (!BASETYPE_VIA_VIRTUAL (type, index) || TYPE_CPLUS_REALLY_JAVA (type))
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 (gdbarch))
error (_("Expected a negative vbase offset (old compiler?)"));
cur_base_offset = cur_base_offset + vtable_address_point_offset (gdbarch);
if ((- cur_base_offset) % TYPE_LENGTH (ptr_type) != 0)
error (_("Misaligned vbase offset."));
cur_base_offset = cur_base_offset / ((int) TYPE_LENGTH (ptr_type));
vtable = gnuv3_get_vtable (gdbarch, type, address + embedded_offset);
gdb_assert (vtable != NULL);
vbase_array = value_field (vtable, vtable_field_vcall_and_vbase_offsets);
base_offset = value_as_long (value_subscript (vbase_array, cur_base_offset));
return base_offset;
}
/* 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 gdbarch *gdbarch;
struct type *vtable_type;
struct type *ptr_type;
struct value *vtable;
struct type *vbasetype;
struct value *offset_val, *vbase_array;
CORE_ADDR vtable_address;
long int cur_base_offset, base_offset;
int vbasetype_vptr_fieldno;
/* Determine architecture. */
gdbarch = get_class_arch (type);
vtable_type = gdbarch_data (gdbarch, vtable_type_gdbarch_data);
ptr_type = builtin_type (gdbarch)->builtin_data_ptr;
/* 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 (gdbarch))
error (_("Expected a negative vbase offset (old compiler?)"));
cur_base_offset = cur_base_offset + vtable_address_point_offset (gdbarch);
if ((- cur_base_offset) % TYPE_LENGTH (ptr_type) != 0)
error (_("Misaligned vbase offset."));
cur_base_offset = cur_base_offset / ((int) TYPE_LENGTH (ptr_type));
/* 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 = check_typedef (TYPE_VPTR_BASETYPE (type));
vbasetype_vptr_fieldno = get_vptr_fieldno (vbasetype, NULL);
if (vbasetype_vptr_fieldno >= 0
&& TYPE_FIELD_BITPOS (vbasetype, vbasetype_vptr_fieldno) != 0)
error (_("Illegal vptr offset in class %s"),
TYPE_NAME (vbasetype) ? TYPE_NAME (vbasetype) : "<unknown>");
vtable_address = value_as_address (value_at_lazy (ptr_type, address));
vtable
= value_at_lazy (vtable_type,
vtable_address - vtable_address_point_offset (gdbarch));
offset_val = value_from_longest (builtin_type_int32, 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 struct type *
gnuv3_rtti_type (struct value *value,
int *full_p, int *top_p, int *using_enc_p)
{
struct gdbarch *gdbarch;
struct type *vtable_type;
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;
struct type *values_type_vptr_basetype;
int values_type_vptr_fieldno;
/* We only have RTTI for class objects. */
if (TYPE_CODE (values_type) != TYPE_CODE_CLASS)
return NULL;
/* This routine may be called for Java types that do not have
a proper objfile. Just return NULL for those. */
if (!TYPE_OBJFILE (values_type)
|| !TYPE_OBJFILE (values_type)->obfd)
return NULL;
/* Determine architecture. */
gdbarch = get_class_arch (values_type);
vtable_type = gdbarch_data (gdbarch, vtable_type_gdbarch_data);
/* If we can't find the virtual table pointer for values_type, we
can't find the RTTI. */
values_type_vptr_fieldno = get_vptr_fieldno (values_type,
&values_type_vptr_basetype);
if (values_type_vptr_fieldno == -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 (values_type_vptr_basetype);
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, values_type_vptr_fieldno));
vtable
= value_at_lazy (vtable_type,
vtable_address - vtable_address_point_offset (gdbarch));
/* Find the linker symbol for this vtable. */
vtable_symbol
= lookup_minimal_symbol_by_pc (value_address (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;
}
