class.c

gcc-2.95.3 Linux下最常用的C编译器

      /* We better not run out of stuff to make it unique.  */
      my_friendly_assert (path != NULL_TREE, 368);

      basetype = TYPE_MAIN_VARIANT (BINFO_TYPE (path));

      if (for_type == basetype)
	{
	  /* If we run out of basetypes in the path, we have already
	     found created a vtable with that name before, we now
	     resort to tacking on _%d to distinguish them.  */
	  int j = 2;
	  i = TYPE_ASSEMBLER_NAME_LENGTH (basetype) + 1 + i + 1 + 3;
	  buf1 = (char *) alloca (i);
	  do {
	    sprintf (buf1, "%s%c%s%c%d",
		     TYPE_ASSEMBLER_NAME_STRING (basetype), joiner,
		     buf2, joiner, j);
	    buf = (char *) alloca (strlen (VTABLE_NAME_FORMAT)
				   + strlen (buf1) + 1);
	    sprintf (buf, VTABLE_NAME_FORMAT, buf1);
	    name = get_identifier (buf);

	    /* If this name doesn't clash, then we can use it,
	       otherwise we add something different to the name until
	       it is unique.  */
	  } while (++j <= 999 && IDENTIFIER_GLOBAL_VALUE (name));

	  /* Hey, they really like MI don't they?  Increase the 3
             above to 6, and the 999 to 999999.  :-)  */
	  my_friendly_assert (j <= 999, 369);

	  break;
	}

      i = TYPE_ASSEMBLER_NAME_LENGTH (basetype) + 1 + i;
      new_buf2 = (char *) alloca (i);
      sprintf (new_buf2, "%s%c%s",
	       TYPE_ASSEMBLER_NAME_STRING (basetype), joiner, buf2);
      buf2 = new_buf2;
    }

  new_decl = build_lang_decl (VAR_DECL, name, TREE_TYPE (orig_decl));
  /* Remember which class this vtable is really for.  */
  DECL_CONTEXT (new_decl) = for_type;

  DECL_ARTIFICIAL (new_decl) = 1;
  TREE_STATIC (new_decl) = 1;
  BINFO_VTABLE (binfo) = pushdecl_top_level (new_decl);
  DECL_VIRTUAL_P (new_decl) = 1;
#ifndef WRITABLE_VTABLES
  /* Make them READONLY by default. (mrs) */
  TREE_READONLY (new_decl) = 1;
#endif
  DECL_ALIGN (new_decl) = DECL_ALIGN (orig_decl);

  /* Make fresh virtual list, so we can smash it later.  */
  BINFO_VIRTUALS (binfo) = copy_list (BINFO_VIRTUALS (binfo));

  if (TREE_VIA_VIRTUAL (binfo))
    {
      tree binfo1 = binfo_member (BINFO_TYPE (binfo), 
				  CLASSTYPE_VBASECLASSES (for_type));

      /* XXX - This should never happen, if it does, the caller should
	 ensure that the binfo is from for_type's binfos, not from any
	 base type's.  We can remove all this code after a while.  */
      if (binfo1 != binfo)
	warning ("internal inconsistency: binfo offset error for rtti");

      offset = BINFO_OFFSET (binfo1);
    }
  else
    offset = BINFO_OFFSET (binfo);

  set_rtti_entry (BINFO_VIRTUALS (binfo),
		  ssize_binop (MINUS_EXPR, integer_zero_node, offset),
		  for_type);

#ifdef GATHER_STATISTICS
  n_vtables += 1;
  n_vtable_elems += list_length (BINFO_VIRTUALS (binfo));
#endif

  /* Set TREE_PUBLIC and TREE_EXTERN as appropriate.  */
  import_export_vtable (new_decl, for_type, 0);

  if (TREE_VIA_VIRTUAL (binfo))
    my_friendly_assert (binfo == binfo_member (BINFO_TYPE (binfo),
				   CLASSTYPE_VBASECLASSES (current_class_type)),
			170);
  SET_BINFO_NEW_VTABLE_MARKED (binfo);
}

/* Return a new vtable for use in initialization of the BASE subobject
   of COMPLETE_TYPE. The vtable there goes into the vfield of the
   VBASEBASE virtual subobject.  */

static tree
prepare_ctor_vtable (complete_type, base, vbasebase)
     tree complete_type, base, vbasebase;
{
  tree orig_decl = BINFO_VTABLE (vbasebase);
  tree name = get_vlist_vtable_id (base, vbasebase);
  tree new_decl;

  new_decl = build_lang_decl (VAR_DECL, name, TREE_TYPE (orig_decl));
  /* Remember which class this vtable is really for.  */
  DECL_CONTEXT (new_decl) = complete_type;

  DECL_ARTIFICIAL (new_decl) = 1;
  TREE_STATIC (new_decl) = 1;
  new_decl = pushdecl_top_level (new_decl);
  DECL_VIRTUAL_P (new_decl) = 1;
#ifndef WRITABLE_VTABLES
  /* Make them READONLY by default. (mrs) */
  TREE_READONLY (new_decl) = 1;
#endif
  DECL_ALIGN (new_decl) = DECL_ALIGN (orig_decl);

#ifdef GATHER_STATISTICS
  n_vtables += 1;
  n_vtable_elems += list_length (BINFO_VIRTUALS (binfo));
#endif

  /* Set TREE_PUBLIC and TREE_EXTERN as appropriate.  */
  import_export_vtable (new_decl, complete_type, 0);

  return new_decl;
}

#if 0
/* Access the virtual function table entry that logically
   contains BASE_FNDECL.  VIRTUALS is the virtual function table's
   initializer.  We can run off the end, when dealing with virtual
   destructors in MI situations, return NULL_TREE in that case.  */

static tree
get_vtable_entry (virtuals, base_fndecl)
     tree virtuals, base_fndecl;
{
  unsigned HOST_WIDE_INT n = (HOST_BITS_PER_WIDE_INT >= BITS_PER_WORD
	   ? (TREE_INT_CST_LOW (DECL_VINDEX (base_fndecl))
	      & (((unsigned HOST_WIDE_INT)1<<(BITS_PER_WORD-1))-1))
	   : TREE_INT_CST_LOW (DECL_VINDEX (base_fndecl)));

#ifdef GATHER_STATISTICS
  n_vtable_searches += n;
#endif

  while (n > 0 && virtuals)
    {
      --n;
      virtuals = TREE_CHAIN (virtuals);
    }
  return virtuals;
}
#endif

/* Put new entry ENTRY into virtual function table initializer
   VIRTUALS.

   Also update DECL_VINDEX (FNDECL).  */

static void
modify_vtable_entry (old_entry_in_list, new_entry, fndecl)
     tree old_entry_in_list, new_entry, fndecl;
{
  tree base_fndecl = TREE_OPERAND (FNADDR_FROM_VTABLE_ENTRY (TREE_VALUE (old_entry_in_list)), 0);

#ifdef NOTQUITE
  cp_warning ("replaced %D with %D", DECL_ASSEMBLER_NAME (base_fndecl),
	      DECL_ASSEMBLER_NAME (fndecl));
#endif
  TREE_VALUE (old_entry_in_list) = new_entry;

  /* Now assign virtual dispatch information, if unset.  */
  /* We can dispatch this, through any overridden base function.  */
  if (TREE_CODE (DECL_VINDEX (fndecl)) != INTEGER_CST)
    {
      DECL_VINDEX (fndecl) = DECL_VINDEX (base_fndecl);
      DECL_CONTEXT (fndecl) = DECL_CONTEXT (base_fndecl);
    }
}

/* Access the virtual function table entry N.  VIRTUALS is the virtual
   function table's initializer.  */

static tree
get_vtable_entry_n (virtuals, n)
     tree virtuals;
     unsigned HOST_WIDE_INT n;
{
  while (n > 0)
    {
      --n;
      virtuals = TREE_CHAIN (virtuals);
    }
  return virtuals;
}

/* Add a virtual function to all the appropriate vtables for the class
   T.  DECL_VINDEX(X) should be error_mark_node, if we want to
   allocate a new slot in our table.  If it is error_mark_node, we
   know that no other function from another vtable is overridden by X.
   HAS_VIRTUAL keeps track of how many virtuals there are in our main
   vtable for the type, and we build upon the PENDING_VIRTUALS list
   and return it.  */

static void
add_virtual_function (pv, phv, has_virtual, fndecl, t)
     tree *pv, *phv;
     int *has_virtual;
     tree fndecl;
     tree t; /* Structure type.  */
{
  tree pending_virtuals = *pv;
  tree pending_hard_virtuals = *phv;

  /* FUNCTION_TYPEs and OFFSET_TYPEs no longer freely
     convert to void *.  Make such a conversion here.  */
  tree vfn = build1 (ADDR_EXPR, vfunc_ptr_type_node, fndecl);
  TREE_CONSTANT (vfn) = 1;

#ifndef DUMB_USER
  if (current_class_type == 0)
    cp_warning ("internal problem, current_class_type is zero when adding `%D', please report",
		fndecl);
  if (current_class_type && t != current_class_type)
    cp_warning ("internal problem, current_class_type differs when adding `%D', please report",
		fndecl);
#endif

  /* If the virtual function is a redefinition of a prior one,
     figure out in which base class the new definition goes,
     and if necessary, make a fresh virtual function table
     to hold that entry.  */
  if (DECL_VINDEX (fndecl) == error_mark_node)
    {
      tree entry;

      /* We remember that this was the base sub-object for rtti.  */
      CLASSTYPE_RTTI (t) = t;

      /* If we are using thunks, use two slots at the front, one
	 for the offset pointer, one for the tdesc pointer.
         For ARM-style vtables, use the same slot for both.  */
      if (*has_virtual == 0 && ! CLASSTYPE_COM_INTERFACE (t))
	{
	  if (flag_vtable_thunks)
	    *has_virtual = 2;
	  else
	    *has_virtual = 1;
	}

      /* Build a new INT_CST for this DECL_VINDEX.  */
      {
	static tree index_table[256];
	tree idx;
	/* We skip a slot for the offset/tdesc entry.  */
	int i = (*has_virtual)++;

	if (i >= 256 || index_table[i] == 0)
	  {
	    idx = build_int_2 (i, 0);
	    if (i < 256)
	      index_table[i] = idx;
	  }
	else
	  idx = index_table[i];

	/* Now assign virtual dispatch information.  */
	DECL_VINDEX (fndecl) = idx;
	DECL_CONTEXT (fndecl) = t;
      }
      entry = build_vtable_entry (integer_zero_node, vfn);
      pending_virtuals = tree_cons (DECL_VINDEX (fndecl), entry, pending_virtuals);
    }
  /* Might already be INTEGER_CST if declared twice in class.  We will
     give error later or we've already given it.  */
  else if (TREE_CODE (DECL_VINDEX (fndecl)) != INTEGER_CST)
    {
      /* Need an entry in some other virtual function table.
         Deal with this after we have laid out our virtual base classes.  */
      pending_hard_virtuals = temp_tree_cons (fndecl, vfn, pending_hard_virtuals);
    }
  *pv = pending_virtuals;
  *phv = pending_hard_virtuals;
}

/* Obstack on which to build the vector of class methods.  */
struct obstack class_obstack;
extern struct obstack *current_obstack;

/* These are method vectors that were too small for the number of
   methods in some class, and so were abandoned.  */
static tree free_method_vecs;

/* Returns a method vector with enough room for N methods.  N should
   be a power of two.  */

static tree
make_method_vec (n)
     int n;
{
  tree new_vec;
  tree* t;
  
  for (t = &free_method_vecs; *t; t = &(TREE_CHAIN (*t)))
    /* Note that we don't use >= n here because we don't want to
       allocate a very large vector where it isn't needed.  */
    if (TREE_VEC_LENGTH (*t) == n)
      {
	new_vec = *t;
	*t = TREE_CHAIN (new_vec);
	TREE_CHAIN (new_vec) = NULL_TREE;
	bzero ((PTR) &TREE_VEC_ELT (new_vec, 0), n * sizeof (tree));
	return new_vec;
      }

  new_vec = make_tree_vec (n);
  return new_vec;
}

/* Free the method vector VEC.  */

static void
free_method_vec (vec)
     tree vec;
{
  TREE_CHAIN (vec) = free_method_vecs;
  free_method_vecs = vec;
}

/* Add method METHOD to class TYPE.

   If non-NULL, FIELDS is the entry in the METHOD_VEC vector entry of
   the class type where the method should be added.  */

void
add_method (type, fields, method)
     tree type, *fields, method;
{
  push_obstacks_nochange ();
  end_temporary_allocation ();

  /* Setting the DECL_CONTEXT and DECL_CLASS_CONTEXT here is probably
     redundant.  */
  DECL_CONTEXT (method) = type;
  DECL_CLASS_CONTEXT (method) = type;
  
  if (fields && *fields)
    *fields = build_overload (method, *fields);
  else 
    {
      int len;
      int slot;
      tree method_vec;

      if (!CLASSTYPE_METHOD_VEC (type))
	/* Make a new method vector.  We start with 8 entries.  We must
	   allocate at least two (for constructors and destructors), and
	   we're going to end up with an assignment operator at some
	   point as well.  

	   We could use a TREE_LIST for now, and convert it to a
	   TREE_VEC in finish_struct, but we would probably waste more
	   memory making the links in the list than we would by
	   over-allocating the size of the vector here.  Furthermore,
	   we would complicate all the code that expects this to be a
	   vector.  We keep a free list of vectors that we outgrew so
	   that we don't really waste any memory.  */
	CLASSTYPE_METHOD_VEC (type) = make_method_vec (8);

      method_vec = CLASSTYPE_METHOD_VEC (type);
      len = TREE_VEC_LENGTH (method_vec);

      if (DECL_NAME (method) == constructor_name (type))
	/* A new constructor or destructor.  Constructors go in 
	   slot 0; destructors go in slot 1.  */
	slot = DESTRUCTOR_NAME_P (DECL_ASSEMBLER_NAME (method)) ? 1 : 0;
      else
	{
	  /* See if we already have an entry with this name.  */
	  for (slot = 2; slot < len; ++slot)
	    if (!TREE_VEC_ELT (method_vec, slot)
		|| (DECL_NAME (OVL_CURRENT (TREE_VEC_ELT (method_vec, 
							  slot))) 
		    == DECL_NAME (method)))
	      break;
		
	  if (slot == len)
	    {
	      /* We need a bigger method vector.  */
	      tree new_vec = make_method_vec (2 * len);
	      bcopy ((PTR) &TREE_VEC_ELT (method_vec, 0),
		     (PTR) &TREE_VEC_ELT (new_vec, 0),
		     len * sizeof (tree));
	      free_method_vec (method_vec);
	      len = 2 * len;
	      method_vec = CLASSTYPE_METHOD_VEC (type) = new_vec;
	    }

	  if (DECL_CONV_FN_P (method) && !TREE_VEC_ELT (method_vec, slot))
	    {
	      /* Type conversion operators have to come before
		 ordinary methods; add_conversions depends on this to
		 speed up looking for conversion operators.  So, if
		 necessary, we slide some of the vector elements up.
		 In theory, this makes this algorithm O(N^2) but we
		 don't expect many conversion operators.  */
	      for (slot = 2; slot < len; ++slot)
		{
		  tree fn = TREE_VEC_ELT (method_vec, slot);
  
		  if (!fn)
		    /* There are no more entries in the vector, so we
		       can insert the new conversion operator here.  */
		    break;