gdb/gnu-v2-abi.c

   1 /* Abstraction of GNU v2 abi.
   2    Contributed by Daniel Berlin <dberlin@redhat.com>
   3    Copyright 2001 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or
   8    modify
   9    it under the terms of the GNU General Public License as published
  10    by
  11    the Free Software Foundation; either version 2 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 59 Temple Place - Suite 330,
  22    Boston, MA 02111-1307, USA.  */
  23
  24 #include "defs.h"
  25 #include "gdb_string.h"
  26 #include "symtab.h"
  27 #include "gdbtypes.h"
  28 #include "value.h"
  29 #include "demangle.h"
  30 #include "cp-abi.h"
  31
  32 #include <ctype.h>
  33
  34 struct cp_abi_ops gnu_v2_abi_ops;
  35
  36 static int vb_match (struct type *, int, struct type *);
  37
  38 static enum dtor_kinds
  39 gnuv2_is_destructor_name (const char *name)
  40 {
  41   if ((name[0] == '_' && is_cplus_marker (name[1]) && name[2] == '_')
  42       || strncmp (name, "__dt__", 6) == 0)
  43     return complete_object_dtor;
  44   else
  45     return 0;
  46 }
  47
  48 static enum ctor_kinds
  49 gnuv2_is_constructor_name (const char *name)
  50 {
  51   if ((name[0] == '_' && name[1] == '_'
  52        && (isdigit (name[2]) || strchr ("Qt", name[2])))
  53       || strncmp (name, "__ct__", 6) == 0)
  54     return complete_object_ctor;
  55   else
  56     return 0;
  57 }
  58
  59 static int
  60 gnuv2_is_vtable_name (const char *name)
  61 {
  62   return (((name)[0] == '_'
  63            && (((name)[1] == 'V' && (name)[2] == 'T')
  64                || ((name)[1] == 'v' && (name)[2] == 't'))
  65            && is_cplus_marker ((name)[3])) ||
  66           ((name)[0] == '_' && (name)[1] == '_'
  67            && (name)[2] == 'v' && (name)[3] == 't' && (name)[4] == '_'));
  68 }
  69
  70 static int
  71 gnuv2_is_operator_name (const char *name)
  72 {
  73   return strncmp (name, "operator", 8) == 0;
  74 }
  75
  76 \f
  77 /* Return a virtual function as a value.
  78    ARG1 is the object which provides the virtual function
  79    table pointer.  *ARG1P is side-effected in calling this function.
  80    F is the list of member functions which contains the desired virtual
  81    function.
  82    J is an index into F which provides the desired virtual function.
  83
  84    TYPE is the type in which F is located.  */
  85 static struct value *
  86 gnuv2_virtual_fn_field (struct value **arg1p, struct fn_field * f, int j,
  87                         struct type * type, int offset)
  88 {
  89   struct value *arg1 = *arg1p;
  90   struct type *type1 = check_typedef (VALUE_TYPE (arg1));
  91
  92
  93   struct type *entry_type;
  94   /* First, get the virtual function table pointer.  That comes
  95      with a strange type, so cast it to type `pointer to long' (which
  96      should serve just fine as a function type).  Then, index into
  97      the table, and convert final value to appropriate function type.  */
  98   struct value *entry;
  99   struct value *vfn;
 100   struct value *vtbl;
 101   struct value *vi = value_from_longest (builtin_type_int,
 102                                      (LONGEST) TYPE_FN_FIELD_VOFFSET (f, j));
 103   struct type *fcontext = TYPE_FN_FIELD_FCONTEXT (f, j);
 104   struct type *context;
 105   if (fcontext == NULL)
 106     /* We don't have an fcontext (e.g. the program was compiled with
 107        g++ version 1).  Try to get the vtbl from the TYPE_VPTR_BASETYPE.
 108        This won't work right for multiple inheritance, but at least we
 109        should do as well as GDB 3.x did.  */
 110     fcontext = TYPE_VPTR_BASETYPE (type);
 111   context = lookup_pointer_type (fcontext);
 112   /* Now context is a pointer to the basetype containing the vtbl.  */
 113   if (TYPE_TARGET_TYPE (context) != type1)
 114     {
 115       struct value *tmp = value_cast (context, value_addr (arg1));
 116       arg1 = value_ind (tmp);
 117       type1 = check_typedef (VALUE_TYPE (arg1));
 118     }
 119
 120   context = type1;
 121   /* Now context is the basetype containing the vtbl.  */
 122
 123   /* This type may have been defined before its virtual function table
 124      was.  If so, fill in the virtual function table entry for the
 125      type now.  */
 126   if (TYPE_VPTR_FIELDNO (context) < 0)
 127     fill_in_vptr_fieldno (context);
 128
 129   /* The virtual function table is now an array of structures
 130      which have the form { int16 offset, delta; void *pfn; }.  */
 131   vtbl = value_primitive_field (arg1, 0, TYPE_VPTR_FIELDNO (context),
 132                                 TYPE_VPTR_BASETYPE (context));
 133
 134   /* With older versions of g++, the vtbl field pointed to an array
 135      of structures.  Nowadays it points directly to the structure. */
 136   if (TYPE_CODE (VALUE_TYPE (vtbl)) == TYPE_CODE_PTR
 137       && TYPE_CODE (TYPE_TARGET_TYPE (VALUE_TYPE (vtbl))) == TYPE_CODE_ARRAY)
 138     {
 139       /* Handle the case where the vtbl field points to an
 140          array of structures. */
 141       vtbl = value_ind (vtbl);
 142
 143       /* Index into the virtual function table.  This is hard-coded because
 144          looking up a field is not cheap, and it may be important to save
 145          time, e.g. if the user has set a conditional breakpoint calling
 146          a virtual function.  */
 147       entry = value_subscript (vtbl, vi);
 148     }
 149   else
 150     {
 151       /* Handle the case where the vtbl field points directly to a structure. */
 152       vtbl = value_add (vtbl, vi);
 153       entry = value_ind (vtbl);
 154     }
 155
 156   entry_type = check_typedef (VALUE_TYPE (entry));
 157
 158   if (TYPE_CODE (entry_type) == TYPE_CODE_STRUCT)
 159     {
 160       /* Move the `this' pointer according to the virtual function table. */
 161       VALUE_OFFSET (arg1) += value_as_long (value_field (entry, 0));
 162
 163       if (!VALUE_LAZY (arg1))
 164         {
 165           VALUE_LAZY (arg1) = 1;
 166           value_fetch_lazy (arg1);
 167         }
 168
 169       vfn = value_field (entry, 2);
 170     }
 171   else if (TYPE_CODE (entry_type) == TYPE_CODE_PTR)
 172     vfn = entry;
 173   else
 174     error ("I'm confused:  virtual function table has bad type");
 175   /* Reinstantiate the function pointer with the correct type.  */
 176   VALUE_TYPE (vfn) = lookup_pointer_type (TYPE_FN_FIELD_TYPE (f, j));
 177
 178   *arg1p = arg1;
 179   return vfn;
 180 }
 181
 182
 183 struct type *
 184 gnuv2_value_rtti_type (struct value *v, int *full, int *top, int *using_enc)
 185 {
 186   struct type *known_type;
 187   struct type *rtti_type;
 188   CORE_ADDR coreptr;
 189   struct value *vp;
 190   int using_enclosing = 0;
 191   long top_offset = 0;
 192   char rtti_type_name[256];
 193   CORE_ADDR vtbl;
 194   struct minimal_symbol *minsym;
 195   struct symbol *sym;
 196   char *demangled_name;
 197   struct type *btype;
 198
 199   if (full)
 200     *full = 0;
 201   if (top)
 202     *top = -1;
 203   if (using_enc)
 204     *using_enc = 0;
 205
 206   /* Get declared type */
 207   known_type = VALUE_TYPE (v);
 208   CHECK_TYPEDEF (known_type);
 209   /* RTTI works only or class objects */
 210   if (TYPE_CODE (known_type) != TYPE_CODE_CLASS)
 211     return NULL;
 212
 213   /* Plan on this changing in the future as i get around to setting
 214      the vtables properly for G++ compiled stuff.  Also, I'll be using
 215      the type info functions, which are always right.  Deal with it
 216      until then.  */
 217
 218   /* If the type has no vptr fieldno, try to get it filled in */
 219   if (TYPE_VPTR_FIELDNO(known_type) < 0)
 220     fill_in_vptr_fieldno(known_type);
 221
 222   /* If we still can't find one, give up */
 223   if (TYPE_VPTR_FIELDNO(known_type) < 0)
 224     return NULL;
 225
 226   /* Make sure our basetype and known type match, otherwise, cast
 227      so we can get at the vtable properly.
 228   */
 229   btype = TYPE_VPTR_BASETYPE (known_type);
 230   CHECK_TYPEDEF (btype);
 231   if (btype != known_type )
 232     {
 233       v = value_cast (btype, v);
 234       if (using_enc)
 235         *using_enc=1;
 236     }
 237   /*
 238     We can't use value_ind here, because it would want to use RTTI, and
 239     we'd waste a bunch of time figuring out we already know the type.
 240     Besides, we don't care about the type, just the actual pointer
 241   */
 242   if (VALUE_ADDRESS (value_field (v, TYPE_VPTR_FIELDNO (known_type))) == 0)
 243     return NULL;
 244
 245   /*
 246     If we are enclosed by something that isn't us, adjust the
 247     address properly and set using_enclosing.
 248   */
 249   if (VALUE_ENCLOSING_TYPE(v) != VALUE_TYPE(v))
 250     {
 251       struct value *tempval;
 252       int bitpos = TYPE_BASECLASS_BITPOS (known_type,
 253                                           TYPE_VPTR_FIELDNO (known_type));
 254       tempval=value_field (v, TYPE_VPTR_FIELDNO(known_type));
 255       VALUE_ADDRESS(tempval) += bitpos / 8;
 256       vtbl=value_as_address (tempval);
 257       using_enclosing=1;
 258     }
 259   else
 260     {
 261       vtbl=value_as_address(value_field(v,TYPE_VPTR_FIELDNO(known_type)));
 262       using_enclosing=0;
 263     }
 264
 265   /* Try to find a symbol that is the vtable */
 266   minsym=lookup_minimal_symbol_by_pc(vtbl);
 267   if (minsym==NULL
 268       || (demangled_name=SYMBOL_NAME(minsym))==NULL
 269       || !is_vtable_name (demangled_name))
 270     return NULL;
 271
 272   /* If we just skip the prefix, we get screwed by namespaces */
 273   demangled_name=cplus_demangle(demangled_name,DMGL_PARAMS|DMGL_ANSI);
 274   *(strchr(demangled_name,' '))=0;
 275
 276   /* Lookup the type for the name */
 277   rtti_type=lookup_typename(demangled_name, (struct block *)0,1);
 278
 279   if (rtti_type==NULL)
 280     return NULL;
 281
 282   if (TYPE_N_BASECLASSES(rtti_type) > 1 &&  full && (*full) != 1)
 283     {
 284       if (top)
 285         *top=TYPE_BASECLASS_BITPOS(rtti_type,TYPE_VPTR_FIELDNO(rtti_type))/8;
 286       if (top && ((*top) >0))
 287         {
 288           if (TYPE_LENGTH(rtti_type) > TYPE_LENGTH(known_type))
 289             {
 290               if (full)
 291                 *full=0;
 292             }
 293           else
 294             {
 295               if (full)
 296                 *full=1;
 297             }
 298         }
 299     }
 300   else
 301     {
 302       if (full)
 303         *full=1;
 304     }
 305   if (using_enc)
 306     *using_enc=using_enclosing;
 307
 308   return rtti_type;
 309 }
 310
 311
 312 static void
 313 init_gnuv2_ops (void)
 314 {
 315   gnu_v2_abi_ops.shortname = "gnu-v2";
 316   gnu_v2_abi_ops.longname = "GNU G++ Version 2 ABI";
 317   gnu_v2_abi_ops.doc = "G++ Version 2 ABI";
 318   gnu_v2_abi_ops.is_destructor_name = gnuv2_is_destructor_name;
 319   gnu_v2_abi_ops.is_constructor_name = gnuv2_is_constructor_name;
 320   gnu_v2_abi_ops.is_vtable_name = gnuv2_is_vtable_name;
 321   gnu_v2_abi_ops.is_operator_name = gnuv2_is_operator_name;
 322   gnu_v2_abi_ops.virtual_fn_field = gnuv2_virtual_fn_field;
 323   gnu_v2_abi_ops.rtti_type = gnuv2_value_rtti_type;
 324 }
 325
 326 void
 327 _initialize_gnu_v2_abi (void)
 328 {
 329   init_gnuv2_ops ();
 330   register_cp_abi (gnu_v2_abi_ops);
 331   switch_to_cp_abi ("gnu-v2");
 332 }