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       VALUE_POINTED_TO_OFFSET (tmp) = 0;
 115       arg1 = value_ind (tmp);
 116       type1 = check_typedef (VALUE_TYPE (arg1));
 117     }
 118
 119   context = type1;
 120   /* Now context is the basetype containing the vtbl.  */
 121
 122   /* This type may have been defined before its virtual function table
 123      was.  If so, fill in the virtual function table entry for the
 124      type now.  */
 125   if (TYPE_VPTR_FIELDNO (context) < 0)
 126     fill_in_vptr_fieldno (context);
 127
 128   /* The virtual function table is now an array of structures
 129      which have the form { int16 offset, delta; void *pfn; }.  */
 130   vtbl = value_primitive_field (arg1, 0, TYPE_VPTR_FIELDNO (context),
 131                                 TYPE_VPTR_BASETYPE (context));
 132
 133   /* With older versions of g++, the vtbl field pointed to an array
 134      of structures.  Nowadays it points directly to the structure. */
 135   if (TYPE_CODE (VALUE_TYPE (vtbl)) == TYPE_CODE_PTR
 136       && TYPE_CODE (TYPE_TARGET_TYPE (VALUE_TYPE (vtbl))) == TYPE_CODE_ARRAY)
 137     {
 138       /* Handle the case where the vtbl field points to an
 139          array of structures. */
 140       vtbl = value_ind (vtbl);
 141
 142       /* Index into the virtual function table.  This is hard-coded because
 143          looking up a field is not cheap, and it may be important to save
 144          time, e.g. if the user has set a conditional breakpoint calling
 145          a virtual function.  */
 146       entry = value_subscript (vtbl, vi);
 147     }
 148   else
 149     {
 150       /* Handle the case where the vtbl field points directly to a structure. */
 151       vtbl = value_add (vtbl, vi);
 152       entry = value_ind (vtbl);
 153     }
 154
 155   entry_type = check_typedef (VALUE_TYPE (entry));
 156
 157   if (TYPE_CODE (entry_type) == TYPE_CODE_STRUCT)
 158     {
 159       /* Move the `this' pointer according to the virtual function table. */
 160       VALUE_OFFSET (arg1) += value_as_long (value_field (entry, 0));
 161
 162       if (!VALUE_LAZY (arg1))
 163         {
 164           VALUE_LAZY (arg1) = 1;
 165           value_fetch_lazy (arg1);
 166         }
 167
 168       vfn = value_field (entry, 2);
 169     }
 170   else if (TYPE_CODE (entry_type) == TYPE_CODE_PTR)
 171     vfn = entry;
 172   else
 173     error ("I'm confused:  virtual function table has bad type");
 174   /* Reinstantiate the function pointer with the correct type.  */
 175   VALUE_TYPE (vfn) = lookup_pointer_type (TYPE_FN_FIELD_TYPE (f, j));
 176
 177   *arg1p = arg1;
 178   return vfn;
 179 }
 180
 181
 182 struct type *
 183 gnuv2_value_rtti_type (value_ptr v, int *full, int *top, int *using_enc)
 184 {
 185   struct type *known_type;
 186   struct type *rtti_type;
 187   CORE_ADDR coreptr;
 188   value_ptr vp;
 189   int using_enclosing = 0;
 190   long top_offset = 0;
 191   char rtti_type_name[256];
 192   CORE_ADDR vtbl;
 193   struct minimal_symbol *minsym;
 194   struct symbol *sym;
 195   char *demangled_name;
 196   struct type *btype;
 197
 198   if (full)
 199     *full = 0;
 200   if (top)
 201     *top = -1;
 202   if (using_enc)
 203     *using_enc = 0;
 204
 205   /* Get declared type */
 206   known_type = VALUE_TYPE (v);
 207   CHECK_TYPEDEF (known_type);
 208   /* RTTI works only or class objects */
 209   if (TYPE_CODE (known_type) != TYPE_CODE_CLASS)
 210     return NULL;
 211
 212   /* Plan on this changing in the future as i get around to setting
 213      the vtables properly for G++ compiled stuff.  Also, I'll be using
 214      the type info functions, which are always right.  Deal with it
 215      until then.  */
 216
 217   /* If the type has no vptr fieldno, try to get it filled in */
 218   if (TYPE_VPTR_FIELDNO(known_type) < 0)
 219     fill_in_vptr_fieldno(known_type);
 220
 221   /* If we still can't find one, give up */
 222   if (TYPE_VPTR_FIELDNO(known_type) < 0)
 223     return NULL;
 224
 225   /* Make sure our basetype and known type match, otherwise, cast
 226      so we can get at the vtable properly.
 227   */
 228   btype = TYPE_VPTR_BASETYPE (known_type);
 229   CHECK_TYPEDEF (btype);
 230   if (btype != known_type )
 231     {
 232       v = value_cast (btype, v);
 233       if (using_enc)
 234         *using_enc=1;
 235     }
 236   /*
 237     We can't use value_ind here, because it would want to use RTTI, and
 238     we'd waste a bunch of time figuring out we already know the type.
 239     Besides, we don't care about the type, just the actual pointer
 240   */
 241   if (VALUE_ADDRESS (value_field (v, TYPE_VPTR_FIELDNO (known_type))) == 0)
 242     return NULL;
 243
 244   /*
 245     If we are enclosed by something that isn't us, adjust the
 246     address properly and set using_enclosing.
 247   */
 248   if (VALUE_ENCLOSING_TYPE(v) != VALUE_TYPE(v))
 249     {
 250       value_ptr tempval;
 251       int bitpos = TYPE_BASECLASS_BITPOS (known_type,
 252                                           TYPE_VPTR_FIELDNO (known_type));
 253       tempval=value_field (v, TYPE_VPTR_FIELDNO(known_type));
 254       VALUE_ADDRESS(tempval) += bitpos / 8;
 255       vtbl=value_as_pointer (tempval);
 256       using_enclosing=1;
 257     }
 258   else
 259     {
 260       vtbl=value_as_pointer(value_field(v,TYPE_VPTR_FIELDNO(known_type)));
 261       using_enclosing=0;
 262     }
 263
 264   /* Try to find a symbol that is the vtable */
 265   minsym=lookup_minimal_symbol_by_pc(vtbl);
 266   if (minsym==NULL
 267       || (demangled_name=SYMBOL_NAME(minsym))==NULL
 268       || !is_vtable_name (demangled_name))
 269     return NULL;
 270
 271   /* If we just skip the prefix, we get screwed by namespaces */
 272   demangled_name=cplus_demangle(demangled_name,DMGL_PARAMS|DMGL_ANSI);
 273   *(strchr(demangled_name,' '))=0;
 274
 275   /* Lookup the type for the name */
 276   rtti_type=lookup_typename(demangled_name, (struct block *)0,1);
 277
 278   if (rtti_type==NULL)
 279     return NULL;
 280
 281   if (TYPE_N_BASECLASSES(rtti_type) > 1 &&  full && (*full) != 1)
 282     {
 283       if (top)
 284         *top=TYPE_BASECLASS_BITPOS(rtti_type,TYPE_VPTR_FIELDNO(rtti_type))/8;
 285       if (top && ((*top) >0))
 286         {
 287           if (TYPE_LENGTH(rtti_type) > TYPE_LENGTH(known_type))
 288             {
 289               if (full)
 290                 *full=0;
 291             }
 292           else
 293             {
 294               if (full)
 295                 *full=1;
 296             }
 297         }
 298     }
 299   else
 300     {
 301       if (full)
 302         *full=1;
 303     }
 304   if (using_enc)
 305     *using_enc=using_enclosing;
 306
 307   return rtti_type;
 308 }
 309
 310
 311 static void
 312 init_gnuv2_ops (void)
 313 {
 314   gnu_v2_abi_ops.shortname = "gnu-v2";
 315   gnu_v2_abi_ops.longname = "GNU G++ Version 2 ABI";
 316   gnu_v2_abi_ops.doc = "G++ Version 2 ABI";
 317   gnu_v2_abi_ops.is_destructor_name = gnuv2_is_destructor_name;
 318   gnu_v2_abi_ops.is_constructor_name = gnuv2_is_constructor_name;
 319   gnu_v2_abi_ops.is_vtable_name = gnuv2_is_vtable_name;
 320   gnu_v2_abi_ops.is_operator_name = gnuv2_is_operator_name;
 321   gnu_v2_abi_ops.virtual_fn_field = gnuv2_virtual_fn_field;
 322   gnu_v2_abi_ops.rtti_type = gnuv2_value_rtti_type;
 323 }
 324
 325 void
 326 _initialize_gnu_v2_abi (void)
 327 {
 328   init_gnuv2_ops ();
 329   register_cp_abi (gnu_v2_abi_ops);
 330   switch_to_cp_abi ("gnu-v2");
 331 }