--- /dev/null
+/* Abstraction of GNU v3 abi.
+ Contributed by Jim Blandy <jimb@redhat.com>
+ Copyright 2001 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 "demangle.h"
+
+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. */
+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. */
+ if (field != field_list + 4)
+ abort ();
+
+ 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 ()
+{
+ struct type *vtable_type = gdbarch_data (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 (vtable_type_gdbarch_data);
+ struct type *value_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 symbol *class_symbol;
+ struct type *run_time_type;
+ LONGEST offset_to_top;
+
+ /* We only have RTTI for class objects. */
+ if (TYPE_CODE (value_type) != TYPE_CODE_CLASS)
+ return NULL;
+
+ /* If we can't find the virtual table pointer for value_type, we
+ can't find the RTTI. */
+ fill_in_vptr_fieldno (value_type);
+ if (TYPE_VPTR_FIELDNO (value_type) == -1)
+ return NULL;
+
+ /* Fetch VALUE's virtual table pointer, and tweak it to point at
+ an instance of our imaginary gdb_gnu_v3_abi_vtable structure. */
+ vtable_address
+ = value_as_pointer (value_field (value, TYPE_VPTR_FIELDNO (value_type)));
+ vtable = value_at_lazy (vtable_type,
+ vtable_address - vtable_address_point_offset (),
+ VALUE_BFD_SECTION (value));
+
+ /* 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 (strncmp (vtable_symbol_name, "vtable for ", 11))
+ error ("can't find linker symbol for virtual table for `%s' value",
+ TYPE_NAME (value_type));
+ class_name = vtable_symbol_name + 11;
+
+ /* Try to look up the class name as a type name. */
+ class_symbol = lookup_symbol (class_name, 0, STRUCT_NAMESPACE, 0, 0);
+ if (! class_symbol)
+ error ("can't find class named `%s', as given by C++ RTTI", class_name);
+
+ /* Make sure the type symbol is sane. (An earlier version of this
+ code would find constructor functions, who have the same name as
+ the class.) */
+ if (SYMBOL_CLASS (class_symbol) != LOC_TYPEDEF
+ || TYPE_CODE (SYMBOL_TYPE (class_symbol)) != TYPE_CODE_CLASS)
+ error ("C++ RTTI gives a class name of `%s', but that isn't a type name",
+ class_name);
+
+ /* This is the object's run-time type! */
+ run_time_type = SYMBOL_TYPE (class_symbol);
+
+ /* 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;
+ if (using_enc_p)
+ *using_enc_p = 0;
+
+ 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 (vtable_type_gdbarch_data);
+ struct value *value = *value_p;
+ struct type *value_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 (value_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);
+
+ /* 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 != value_type)
+ /* It would be nicer to simply cast the value to the appropriate
+ base class (and I think that is supposed to be legal), but
+ value_cast only does the right magic when casting pointers. */
+ value = value_ind (value_cast (vfn_base, value_addr (value)));
+
+ /* Now value is an object of the appropriate base type. Fetch its
+ virtual table. */
+ vtable_address
+ = value_as_pointer (value_field (value, TYPE_VPTR_FIELDNO (vfn_base)));
+ vtable = value_at_lazy (vtable_type,
+ vtable_address - vtable_address_point_offset (),
+ VALUE_BFD_SECTION (value));
+
+ /* 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);
+
+ return vfn;
+}
+
+
+static void
+init_gnuv3_ops (void)
+{
+ vtable_type_gdbarch_data = register_gdbarch_data (build_gdb_vtable_type, 0);
+
+ 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 = is_gnu_v3_mangled_dtor;
+ gnu_v3_abi_ops.is_constructor_name = 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;
+}
+
+
+void
+_initialize_gnu_v3_abi (void)
+{
+ init_gnuv3_ops ();
+
+ register_cp_abi (gnu_v3_abi_ops);
+}
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