Add support for the GNU V3 C++ ABI.

(Includes changes by Dan Berlin.)

* gnu-v3-abi.c: New file.
* minsyms.c: #include "value.h" and "cp-abi.h".
(install_minimal_symbols): Check the minimal symbol table for
symbols that look mangled in the V3 style, and select the V3 ABI
if we find any.
* Makefile.in (SFILES): Add gnu-v3-abi.c.
(COMMON_OBS): Add gnu-v3-abi.o.
(gnu-v3-abi.o): Add new rule.
(minsyms.o): Depend on $(cp_abi_h) and $(value_h).

1 files changed, 355 insertions, 0 deletions

diff --git a/gdb/gnu-v3-abi.c b/gdb/gnu-v3-abi.c
new file mode 100644
index 0000000..1bd4ce6
--- /dev/null
+++ b/gdb/gnu-v3-abi.c
@@ -0,0 +1,355 @@
+/* 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);
+}