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 value_ptr
  86 gnuv2_virtual_fn_field (value_ptr * arg1p, struct fn_field * f, int j,
  87                         struct type * type, int offset)
  88 {
  89   value_ptr 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   value_ptr entry, vfn, vtbl;
  99   value_ptr vi = value_from_longest (builtin_type_int,
 100                                      (LONGEST) TYPE_FN_FIELD_VOFFSET (f, j));
 101   struct type *fcontext = TYPE_FN_FIELD_FCONTEXT (f, j);
 102   struct type *context;
 103   if (fcontext == NULL)
 104     /* We don't have an fcontext (e.g. the program was compiled with
 105        g++ version 1).  Try to get the vtbl from the TYPE_VPTR_BASETYPE.
 106        This won't work right for multiple inheritance, but at least we
 107        should do as well as GDB 3.x did.  */
 108     fcontext = TYPE_VPTR_BASETYPE (type);
 109   context = lookup_pointer_type (fcontext);
 110   /* Now context is a pointer to the basetype containing the vtbl.  */
 111   if (TYPE_TARGET_TYPE (context) != type1)
 112     {
 113       value_ptr tmp = value_cast (context, value_addr (arg1));
 114       arg1 = value_ind (tmp);
 115       type1 = check_typedef (VALUE_TYPE (arg1));
 116     }
 117
 118   context = type1;
 119   /* Now context is the basetype containing the vtbl.  */
 120
 121   /* This type may have been defined before its virtual function table
 122      was.  If so, fill in the virtual function table entry for the
 123      type now.  */
 124   if (TYPE_VPTR_FIELDNO (context) < 0)
 125     fill_in_vptr_fieldno (context);
 126
 127   /* The virtual function table is now an array of structures
 128      which have the form { int16 offset, delta; void *pfn; }.  */
 129   vtbl = value_primitive_field (arg1, 0, TYPE_VPTR_FIELDNO (context),
 130                                 TYPE_VPTR_BASETYPE (context));
 131
 132   /* With older versions of g++, the vtbl field pointed to an array
 133      of structures.  Nowadays it points directly to the structure. */
 134   if (TYPE_CODE (VALUE_TYPE (vtbl)) == TYPE_CODE_PTR
 135       && TYPE_CODE (TYPE_TARGET_TYPE (VALUE_TYPE (vtbl))) == TYPE_CODE_ARRAY)
 136     {
 137       /* Handle the case where the vtbl field points to an
 138          array of structures. */
 139       vtbl = value_ind (vtbl);
 140
 141       /* Index into the virtual function table.  This is hard-coded because
 142          looking up a field is not cheap, and it may be important to save
 143          time, e.g. if the user has set a conditional breakpoint calling
 144          a virtual function.  */
 145       entry = value_subscript (vtbl, vi);
 146     }
 147   else
 148     {
 149       /* Handle the case where the vtbl field points directly to a structure. */
 150       vtbl = value_add (vtbl, vi);
 151       entry = value_ind (vtbl);
 152     }
 153
 154   entry_type = check_typedef (VALUE_TYPE (entry));
 155
 156   if (TYPE_CODE (entry_type) == TYPE_CODE_STRUCT)
 157     {
 158       /* Move the `this' pointer according to the virtual function table. */
 159       VALUE_OFFSET (arg1) += value_as_long (value_field (entry, 0));
 160
 161       if (!VALUE_LAZY (arg1))
 162         {
 163           VALUE_LAZY (arg1) = 1;
 164           value_fetch_lazy (arg1);
 165         }
 166
 167       vfn = value_field (entry, 2);
 168     }
 169   else if (TYPE_CODE (entry_type) == TYPE_CODE_PTR)
 170     vfn = entry;
 171   else
 172     error ("I'm confused:  virtual function table has bad type");
 173   /* Reinstantiate the function pointer with the correct type.  */
 174   VALUE_TYPE (vfn) = lookup_pointer_type (TYPE_FN_FIELD_TYPE (f, j));
 175
 176   *arg1p = arg1;
 177   return vfn;
 178 }
 179
 180
 181 struct type *
 182 gnuv2_value_rtti_type (value_ptr v, int *full, int *top, int *using_enc)
 183 {
 184   struct type *known_type;
 185   struct type *rtti_type;
 186   CORE_ADDR coreptr;
 187   value_ptr vp;
 188   int using_enclosing = 0;
 189   long top_offset = 0;
 190   char rtti_type_name[256];
 191   CORE_ADDR vtbl;
 192   struct minimal_symbol *minsym;
 193   struct symbol *sym;
 194   char *demangled_name;
 195   struct type *btype;
 196
 197   if (full)
 198     *full = 0;
 199   if (top)
 200     *top = -1;
 201   if (using_enc)
 202     *using_enc = 0;
 203
 204   /* Get declared type */
 205   known_type = VALUE_TYPE (v);
 206   CHECK_TYPEDEF (known_type);
 207   /* RTTI works only or class objects */
 208   if (TYPE_CODE (known_type) != TYPE_CODE_CLASS)
 209     return NULL;
 210
 211   /* Plan on this changing in the future as i get around to setting
 212      the vtables properly for G++ compiled stuff.  Also, I'll be using
 213      the type info functions, which are always right.  Deal with it
 214      until then.  */
 215
 216   /* If the type has no vptr fieldno, try to get it filled in */
 217   if (TYPE_VPTR_FIELDNO(known_type) < 0)
 218     fill_in_vptr_fieldno(known_type);
 219
 220   /* If we still can't find one, give up */
 221   if (TYPE_VPTR_FIELDNO(known_type) < 0)
 222     return NULL;
 223
 224   /* Make sure our basetype and known type match, otherwise, cast
 225      so we can get at the vtable properly.
 226   */
 227   btype = TYPE_VPTR_BASETYPE (known_type);
 228   CHECK_TYPEDEF (btype);
 229   if (btype != known_type )
 230     {
 231       v = value_cast (btype, v);
 232       if (using_enc)
 233         *using_enc=1;
 234     }
 235   /*
 236     We can't use value_ind here, because it would want to use RTTI, and
 237     we'd waste a bunch of time figuring out we already know the type.
 238     Besides, we don't care about the type, just the actual pointer
 239   */
 240   if (VALUE_ADDRESS (value_field (v, TYPE_VPTR_FIELDNO (known_type))) == 0)
 241     return NULL;
 242
 243   /*
 244     If we are enclosed by something that isn't us, adjust the
 245     address properly and set using_enclosing.
 246   */
 247   if (VALUE_ENCLOSING_TYPE(v) != VALUE_TYPE(v))
 248     {
 249       value_ptr tempval;
 250       int bitpos = TYPE_BASECLASS_BITPOS (known_type,
 251                                           TYPE_VPTR_FIELDNO (known_type));
 252       tempval=value_field (v, TYPE_VPTR_FIELDNO(known_type));
 253       VALUE_ADDRESS(tempval) += bitpos / 8;
 254       vtbl=value_as_address (tempval);
 255       using_enclosing=1;
 256     }
 257   else
 258     {
 259       vtbl=value_as_address(value_field(v,TYPE_VPTR_FIELDNO(known_type)));
 260       using_enclosing=0;
 261     }
 262
 263   /* Try to find a symbol that is the vtable */
 264   minsym=lookup_minimal_symbol_by_pc(vtbl);
 265   if (minsym==NULL
 266       || (demangled_name=SYMBOL_NAME(minsym))==NULL
 267       || !is_vtable_name (demangled_name))
 268     return NULL;
 269
 270   /* If we just skip the prefix, we get screwed by namespaces */
 271   demangled_name=cplus_demangle(demangled_name,DMGL_PARAMS|DMGL_ANSI);
 272   *(strchr(demangled_name,' '))=0;
 273
 274   /* Lookup the type for the name */
 275   rtti_type=lookup_typename(demangled_name, (struct block *)0,1);
 276
 277   if (rtti_type==NULL)
 278     return NULL;
 279
 280   if (TYPE_N_BASECLASSES(rtti_type) > 1 &&  full && (*full) != 1)
 281     {
 282       if (top)
 283         *top=TYPE_BASECLASS_BITPOS(rtti_type,TYPE_VPTR_FIELDNO(rtti_type))/8;
 284       if (top && ((*top) >0))
 285         {
 286           if (TYPE_LENGTH(rtti_type) > TYPE_LENGTH(known_type))
 287             {
 288               if (full)
 289                 *full=0;
 290             }
 291           else
 292             {
 293               if (full)
 294                 *full=1;
 295             }
 296         }
 297     }
 298   else
 299     {
 300       if (full)
 301         *full=1;
 302     }
 303   if (using_enc)
 304     *using_enc=using_enclosing;
 305
 306   return rtti_type;
 307 }
 308
 309
 310 static void
 311 init_gnuv2_ops (void)
 312 {
 313   gnu_v2_abi_ops.shortname = "gnu-v2";
 314   gnu_v2_abi_ops.longname = "GNU G++ Version 2 ABI";
 315   gnu_v2_abi_ops.doc = "G++ Version 2 ABI";
 316   gnu_v2_abi_ops.is_destructor_name = gnuv2_is_destructor_name;
 317   gnu_v2_abi_ops.is_constructor_name = gnuv2_is_constructor_name;
 318   gnu_v2_abi_ops.is_vtable_name = gnuv2_is_vtable_name;
 319   gnu_v2_abi_ops.is_operator_name = gnuv2_is_operator_name;
 320   gnu_v2_abi_ops.virtual_fn_field = gnuv2_virtual_fn_field;
 321   gnu_v2_abi_ops.rtti_type = gnuv2_value_rtti_type;
 322 }
 323
 324 void
 325 _initialize_gnu_v2_abi (void)
 326 {
 327   init_gnuv2_ops ();
 328   register_cp_abi (gnu_v2_abi_ops);
 329   switch_to_cp_abi ("gnu-v2");
 330 }