static struct type *
gnuv2_value_rtti_type (struct value *v, int *full, int *top, int *using_enc)
{
struct type *known_type;
struct type *rtti_type;
CORE_ADDR vtbl;
struct minimal_symbol *minsym;
char *demangled_name;
struct type *btype;
if (full)
*full = 0;
if (top)
*top = -1;
if (using_enc)
*using_enc = 0;
/* Get declared type */
known_type = value_type (v);
CHECK_TYPEDEF (known_type);
/* RTTI works only or class objects */
if (TYPE_CODE (known_type) != TYPE_CODE_CLASS)
return NULL;
/* Plan on this changing in the future as i get around to setting
the vtables properly for G++ compiled stuff. Also, I'll be using
the type info functions, which are always right. Deal with it
until then.
JCI - This pretty much useless. This gets the "true" type
correctly when there is single inheritance - but in all such
cases that I could find gdb already knows that. In cases
where this points INTO the object (like non-virtual diamond
graphs) the demangled name is something like OUTER::INNER
and this is not a symbol gdb can resolve, so we fail & return
NULL anyway. Seems like this really isn't going to work till
we actually call the RTTI function & parse it.
*/
/* If the type has no vptr fieldno, try to get it filled in */
if (TYPE_VPTR_FIELDNO(known_type) < 0)
fill_in_vptr_fieldno(known_type);
/* If we still can't find one, give up */
if (TYPE_VPTR_FIELDNO(known_type) < 0)
return NULL;
/* Make sure our basetype and known type match, otherwise, cast
so we can get at the vtable properly.
*/
btype = TYPE_VPTR_BASETYPE (known_type);
CHECK_TYPEDEF (btype);
if (btype != known_type )
{
v = value_cast (btype, v);
if (using_enc)
*using_enc=1;
}
/*
We can't use value_ind here, because it would want to use RTTI, and
we'd waste a bunch of time figuring out we already know the type.
Besides, we don't care about the type, just the actual pointer
*/
if (VALUE_ADDRESS (value_field (v, TYPE_VPTR_FIELDNO (known_type))) == 0)
return NULL;
vtbl=value_as_address(value_field(v,TYPE_VPTR_FIELDNO(known_type)));
/* Try to find a symbol that is the vtable */
minsym=lookup_minimal_symbol_by_pc(vtbl);
if (minsym==NULL
|| (demangled_name=DEPRECATED_SYMBOL_NAME (minsym))==NULL
|| !is_vtable_name (demangled_name))
return NULL;
/* If we just skip the prefix, we get screwed by namespaces */
demangled_name=cplus_demangle(demangled_name,DMGL_PARAMS|DMGL_ANSI);
*(strchr(demangled_name,' '))=0;
/* Lookup the type for the name */
/* FIXME: chastain/2003-11-26: block=NULL is bogus. See pr gdb/1465. */
rtti_type = cp_lookup_rtti_type (demangled_name, NULL);
if (rtti_type == NULL)
return NULL;
if (TYPE_N_BASECLASSES(rtti_type) > 1 && full && (*full) != 1)
{
if (top)
*top=TYPE_BASECLASS_BITPOS(rtti_type,TYPE_VPTR_FIELDNO(rtti_type))/8;
if (top && ((*top) >0))
{
if (TYPE_LENGTH(rtti_type) > TYPE_LENGTH(known_type))
{
if (full)
*full=0;
}
else
{
if (full)
*full=1;
}
}
}
else
{
if (full)
*full=1;
}
return rtti_type;
}
/* Return a virtual function as a value.
ARG1 is the object which provides the virtual function
table pointer. *ARG1P is side-effected in calling this function.
F is the list of member functions which contains the desired virtual
function.
J is an index into F which provides the desired virtual function.
TYPE is the type in which F is located. */
static struct value *
gnuv2_virtual_fn_field (struct value **arg1p, struct fn_field * f, int j,
struct type * type, int offset)
{
struct value *arg1 = *arg1p;
struct type *type1 = check_typedef (value_type (arg1));
struct type *entry_type;
/* First, get the virtual function table pointer. That comes
with a strange type, so cast it to type `pointer to long' (which
should serve just fine as a function type). Then, index into
the table, and convert final value to appropriate function type. */
struct value *entry;
struct value *vfn;
struct value *vtbl;
struct value *vi = value_from_longest (builtin_type_int,
(LONGEST) TYPE_FN_FIELD_VOFFSET (f, j));
struct type *fcontext = TYPE_FN_FIELD_FCONTEXT (f, j);
struct type *context;
if (fcontext == NULL)
/* We don't have an fcontext (e.g. the program was compiled with
g++ version 1). Try to get the vtbl from the TYPE_VPTR_BASETYPE.
This won't work right for multiple inheritance, but at least we
should do as well as GDB 3.x did. */
fcontext = TYPE_VPTR_BASETYPE (type);
context = lookup_pointer_type (fcontext);
/* Now context is a pointer to the basetype containing the vtbl. */
if (TYPE_TARGET_TYPE (context) != type1)
{
struct value *tmp = value_cast (context, value_addr (arg1));
arg1 = value_ind (tmp);
type1 = check_typedef (value_type (arg1));
}
context = type1;
/* Now context is the basetype containing the vtbl. */
/* 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 (context) < 0)
fill_in_vptr_fieldno (context);
/* The virtual function table is now an array of structures
which have the form { int16 offset, delta; void *pfn; }. */
vtbl = value_primitive_field (arg1, 0, TYPE_VPTR_FIELDNO (context),
TYPE_VPTR_BASETYPE (context));
/* With older versions of g++, the vtbl field pointed to an array
of structures. Nowadays it points directly to the structure. */
if (TYPE_CODE (value_type (vtbl)) == TYPE_CODE_PTR
&& TYPE_CODE (TYPE_TARGET_TYPE (value_type (vtbl))) == TYPE_CODE_ARRAY)
{
/* Handle the case where the vtbl field points to an
array of structures. */
vtbl = value_ind (vtbl);
/* Index into the virtual function table. This is hard-coded because
looking up a field is not cheap, and it may be important to save
time, e.g. if the user has set a conditional breakpoint calling
a virtual function. */
entry = value_subscript (vtbl, vi);
}
else
{
/* Handle the case where the vtbl field points directly to a structure. */
vtbl = value_add (vtbl, vi);
entry = value_ind (vtbl);
}
entry_type = check_typedef (value_type (entry));
if (TYPE_CODE (entry_type) == TYPE_CODE_STRUCT)
{
/* Move the `this' pointer according to the virtual function table. */
set_value_offset (arg1, value_offset (arg1) + value_as_long (value_field (entry, 0)));
if (!value_lazy (arg1))
{
set_value_lazy (arg1, 1);
value_fetch_lazy (arg1);
}
vfn = value_field (entry, 2);
}
else if (TYPE_CODE (entry_type) == TYPE_CODE_PTR)
vfn = entry;
else
error (_("I'm confused: virtual function table has bad type"));
/* Reinstantiate the function pointer with the correct type. */
deprecated_set_value_type (vfn, lookup_pointer_type (TYPE_FN_FIELD_TYPE (f, j)));
*arg1p = arg1;
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 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;
}
