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/* Abstraction of GNU v2 abi.

   Copyright (C) 2001, 2002, 2003, 2005, 2007, 2008, 2009, 2010

   Free Software Foundation, Inc.

   Contributed by Daniel Berlin <dberlin@redhat.com>

   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 3 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, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"

#include "gdb_string.h"

#include "symtab.h"

#include "gdbtypes.h"

#include "value.h"

#include "demangle.h"

#include "cp-abi.h"

#include "cp-support.h"

#include <ctype.h>

struct cp_abi_ops gnu_v2_abi_ops;

static int vb_match (struct type *, int, struct type *);

static enum dtor_kinds

gnuv2_is_destructor_name (const char *name)

{

  if ((name[0] == '_' && is_cplus_marker (name[1]) && name[2] == '_')

      || strncmp (name, "__dt__", 6) == 0)

    return complete_object_dtor;

  else

    return 0;

}

static enum ctor_kinds

gnuv2_is_constructor_name (const char *name)

{

  if ((name[0] == '_' && name[1] == '_'

       && (isdigit (name[2]) || strchr ("Qt", name[2])))

      || strncmp (name, "__ct__", 6) == 0)

    return complete_object_ctor;

  else

    return 0;

}

static int

gnuv2_is_vtable_name (const char *name)

{

  return (((name)[0] == '_'

           && (((name)[1] == 'V' && (name)[2] == 'T')

               || ((name)[1] == 'v' && (name)[2] == 't'))

           && is_cplus_marker ((name)[3])) ||

          ((name)[0] == '_' && (name)[1] == '_'

           && (name)[2] == 'v' && (name)[3] == 't' && (name)[4] == '_'));

}

static int

gnuv2_is_operator_name (const char *name)

{

  return strncmp (name, "operator", 8) == 0;

}

/* Return a virtual function as a value.

   ARG1 is the object which provides the virtual function

   table pointer.  *ARG1P is side-effected in calling this function.

   F is the list of member functions which contains the desired virtual

   function.

   J is an index into F which provides the desired virtual function.

   TYPE is the type in which F is located.  */

static struct value *

gnuv2_virtual_fn_field (struct value **arg1p, struct fn_field * f, int j,

                        struct type * type, int offset)

{

  struct value *arg1 = *arg1p;

  struct type *type1 = check_typedef (value_type (arg1));

  struct type *entry_type;

  /* First, get the virtual function table pointer.  That comes

     with a strange type, so cast it to type `pointer to long' (which

     should serve just fine as a function type).  Then, index into

     the table, and convert final value to appropriate function type.  */

  struct value *entry;

  struct value *vfn;

  struct value *vtbl;

  LONGEST vi = (LONGEST) TYPE_FN_FIELD_VOFFSET (f, j);

  struct type *fcontext = TYPE_FN_FIELD_FCONTEXT (f, j);

  struct type *context;

  struct type *context_vptr_basetype;

  int context_vptr_fieldno;

  if (fcontext == NULL)

    /* We don't have an fcontext (e.g. the program was compiled with

       g++ version 1).  Try to get the vtbl from the TYPE_VPTR_BASETYPE.

       This won't work right for multiple inheritance, but at least we

       should do as well as GDB 3.x did.  */

    fcontext = TYPE_VPTR_BASETYPE (type);

  context = lookup_pointer_type (fcontext);

  /* Now context is a pointer to the basetype containing the vtbl.  */

  if (TYPE_TARGET_TYPE (context) != type1)

    {

      struct value *tmp = value_cast (context, value_addr (arg1));

      arg1 = value_ind (tmp);

      type1 = check_typedef (value_type (arg1));

    }

  context = type1;

  /* Now context is the basetype containing the vtbl.  */

  /* 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.  */

  context_vptr_fieldno = get_vptr_fieldno (context, &context_vptr_basetype);

  /* FIXME: What to do if vptr_fieldno is still -1?  */

  /* The virtual function table is now an array of structures

     which have the form { int16 offset, delta; void *pfn; }.  */

  vtbl = value_primitive_field (arg1, 0, context_vptr_fieldno,

                                context_vptr_basetype);

  /* With older versions of g++, the vtbl field pointed to an array

     of structures.  Nowadays it points directly to the structure. */

  if (TYPE_CODE (value_type (vtbl)) == TYPE_CODE_PTR

      && TYPE_CODE (TYPE_TARGET_TYPE (value_type (vtbl))) == TYPE_CODE_ARRAY)

    {

      /* Handle the case where the vtbl field points to an

         array of structures. */

      vtbl = value_ind (vtbl);

      /* Index into the virtual function table.  This is hard-coded because

         looking up a field is not cheap, and it may be important to save

         time, e.g. if the user has set a conditional breakpoint calling

         a virtual function.  */

      entry = value_subscript (vtbl, vi);

    }

  else

    {

      /* Handle the case where the vtbl field points directly to a structure. */

      vtbl = value_ptradd (vtbl, vi);

      entry = value_ind (vtbl);

    }

  entry_type = check_typedef (value_type (entry));

  if (TYPE_CODE (entry_type) == TYPE_CODE_STRUCT)

    {

      /* Move the `this' pointer according to the virtual function table. */

      set_value_offset (arg1, value_offset (arg1) + value_as_long (value_field (entry, 0)));

      if (!value_lazy (arg1))

        {

          set_value_lazy (arg1, 1);

          value_fetch_lazy (arg1);

        }

      vfn = value_field (entry, 2);

    }

  else if (TYPE_CODE (entry_type) == TYPE_CODE_PTR)

    vfn = entry;

  else

    error (_("I'm confused:  virtual function table has bad type"));

  /* Reinstantiate the function pointer with the correct type.  */

  deprecated_set_value_type (vfn, lookup_pointer_type (TYPE_FN_FIELD_TYPE (f, j)));

  *arg1p = arg1;

  return vfn;

}

static struct type *

gnuv2_value_rtti_type (struct value *v, int *full, int *top, int *using_enc)

{

  struct type *known_type;

  struct type *rtti_type;

  CORE_ADDR vtbl;

  struct minimal_symbol *minsym;

  char *demangled_name, *p;

  struct type *btype;

  struct type *known_type_vptr_basetype;

  int known_type_vptr_fieldno;

  if (full)

    *full = 0;

  if (top)

    *top = -1;

  if (using_enc)

    *using_enc = 0;

  /* Get declared type */

  known_type = value_type (v);

  CHECK_TYPEDEF (known_type);

  /* RTTI works only or class objects */

  if (TYPE_CODE (known_type) != TYPE_CODE_CLASS)

    return NULL;

  /* Plan on this changing in the future as i get around to setting

     the vtables properly for G++ compiled stuff.  Also, I'll be using

     the type info functions, which are always right.  Deal with it

     until then.  */

  /* Try to get the vptr basetype, fieldno.  */

  known_type_vptr_fieldno = get_vptr_fieldno (known_type,

                                              &known_type_vptr_basetype);

  /* If we can't find it, give up.  */

  if (known_type_vptr_fieldno < 0)

    return NULL;

  /* Make sure our basetype and known type match, otherwise, cast

     so we can get at the vtable properly.

  */

  btype = known_type_vptr_basetype;

  CHECK_TYPEDEF (btype);

  if (btype != known_type )

    {

      v = value_cast (btype, v);

      if (using_enc)

        *using_enc=1;

    }

  /*

    We can't use value_ind here, because it would want to use RTTI, and

    we'd waste a bunch of time figuring out we already know the type.

    Besides, we don't care about the type, just the actual pointer

  */

  if (value_address (value_field (v, known_type_vptr_fieldno)) == 0)

    return NULL;

  vtbl = value_as_address (value_field (v, known_type_vptr_fieldno));

  /* Try to find a symbol that is the vtable */

  minsym=lookup_minimal_symbol_by_pc(vtbl);

  if (minsym==NULL

      || (demangled_name=SYMBOL_LINKAGE_NAME (minsym))==NULL

      || !is_vtable_name (demangled_name))

    return NULL;

  /* If we just skip the prefix, we get screwed by namespaces */

  demangled_name=cplus_demangle(demangled_name,DMGL_PARAMS|DMGL_ANSI);

  p = strchr (demangled_name, ' ');

  if (p)

    *p = '\0';

  /* Lookup the type for the name */

  /* FIXME: chastain/2003-11-26: block=NULL is bogus.  See pr gdb/1465. */

  rtti_type = cp_lookup_rtti_type (demangled_name, NULL);

  if (rtti_type == NULL)

    return NULL;

  if (TYPE_N_BASECLASSES(rtti_type) > 1 &&  full && (*full) != 1)

    {

      if (top)

        *top=TYPE_BASECLASS_BITPOS(rtti_type,TYPE_VPTR_FIELDNO(rtti_type))/8;

      if (top && ((*top) >0))

        {

          if (TYPE_LENGTH(rtti_type) > TYPE_LENGTH(known_type))

            {

              if (full)

                *full=0;

            }

          else

            {

              if (full)

                *full=1;

            }

        }

    }

  else

    {

      if (full)

        *full=1;

    }

  return rtti_type;

}

/* Return true if the INDEXth field of TYPE is a virtual baseclass

   pointer which is for the base class whose type is BASECLASS.  */

static int

vb_match (struct type *type, int index, struct type *basetype)

{

  struct type *fieldtype;

  char *name = TYPE_FIELD_NAME (type, index);

  char *field_class_name = NULL;

  if (*name != '_')

    return 0;

  /* gcc 2.4 uses _vb$.  */

  if (name[1] == 'v' && name[2] == 'b' && is_cplus_marker (name[3]))

    field_class_name = name + 4;

  /* gcc 2.5 will use __vb_.  */

  if (name[1] == '_' && name[2] == 'v' && name[3] == 'b' && name[4] == '_')

    field_class_name = name + 5;

  if (field_class_name == NULL)

    /* This field is not a virtual base class pointer.  */

    return 0;

  /* It's a virtual baseclass pointer, now we just need to find out whether

     it is for this baseclass.  */

  fieldtype = TYPE_FIELD_TYPE (type, index);

  if (fieldtype == NULL

      || TYPE_CODE (fieldtype) != TYPE_CODE_PTR)

    /* "Can't happen".  */

    return 0;

  /* What we check for is that either the types are equal (needed for

     nameless types) or have the same name.  This is ugly, and a more

     elegant solution should be devised (which would probably just push

     the ugliness into symbol reading unless we change the stabs format).  */

  if (TYPE_TARGET_TYPE (fieldtype) == basetype)

    return 1;

  if (TYPE_NAME (basetype) != NULL

      && TYPE_NAME (TYPE_TARGET_TYPE (fieldtype)) != NULL

      && strcmp (TYPE_NAME (basetype),

                 TYPE_NAME (TYPE_TARGET_TYPE (fieldtype))) == 0)

    return 1;

  return 0;

}

/* Compute the offset of the baseclass which is

   the INDEXth baseclass of class TYPE,

   for value at VALADDR (in host) at ADDRESS (in target).

   The result is the offset of the baseclass value relative

   to (the address of)(ARG) + OFFSET.

   -1 is returned on error. */

static int

gnuv2_baseclass_offset (struct type *type, int index,

                        const bfd_byte *valaddr, CORE_ADDR address)

{

  struct type *basetype = TYPE_BASECLASS (type, index);

  if (BASETYPE_VIA_VIRTUAL (type, index))

    {

      /* Must hunt for the pointer to this virtual baseclass.  */

      int i, len = TYPE_NFIELDS (type);

      int n_baseclasses = TYPE_N_BASECLASSES (type);

      /* First look for the virtual baseclass pointer

         in the fields.  */

      for (i = n_baseclasses; i < len; i++)

        {

          if (vb_match (type, i, basetype))

            {

              CORE_ADDR addr

                = unpack_pointer (TYPE_FIELD_TYPE (type, i),

                                  valaddr + (TYPE_FIELD_BITPOS (type, i) / 8));

              return addr - (LONGEST) address;

            }

        }

      /* Not in the fields, so try looking through the baseclasses.  */

      for (i = index + 1; i < n_baseclasses; i++)

        {

          int boffset =

            baseclass_offset (type, i, valaddr, address);

          if (boffset)

            return boffset;

        }

      /* Not found.  */

      return -1;

    }

  /* Baseclass is easily computed.  */

  return TYPE_BASECLASS_BITPOS (type, index) / 8;

}

static void

init_gnuv2_ops (void)

{

  gnu_v2_abi_ops.shortname = "gnu-v2";

  gnu_v2_abi_ops.longname = "GNU G++ Version 2 ABI";

  gnu_v2_abi_ops.doc = "G++ Version 2 ABI";

  gnu_v2_abi_ops.is_destructor_name = gnuv2_is_destructor_name;

  gnu_v2_abi_ops.is_constructor_name = gnuv2_is_constructor_name;

  gnu_v2_abi_ops.is_vtable_name = gnuv2_is_vtable_name;

  gnu_v2_abi_ops.is_operator_name = gnuv2_is_operator_name;

  gnu_v2_abi_ops.virtual_fn_field = gnuv2_virtual_fn_field;

  gnu_v2_abi_ops.rtti_type = gnuv2_value_rtti_type;

  gnu_v2_abi_ops.baseclass_offset = gnuv2_baseclass_offset;

}

extern initialize_file_ftype _initialize_gnu_v2_abi; /* -Wmissing-prototypes */

void

_initialize_gnu_v2_abi (void)

{

  init_gnuv2_ops ();

  register_cp_abi (&gnu_v2_abi_ops);

  set_cp_abi_as_auto_default (gnu_v2_abi_ops.shortname);

}