search.c

GCC编译器源代码

  if (flag_memoize_lookups)
    {
      len = type_stack->len;
      while (len--)
	CLASSTYPE_MTABLE_ENTRY (tem[len*2])
	  = (char *)MEMOIZED_CHAIN (CLASSTYPE_MTABLE_ENTRY (tem[len*2]));
    }
  if (! use_old)
    type_stack = pop_type_level (type_stack);
  else
    type_stack = (struct type_level *)type_stack->base.prev;
}

/* Get a virtual binfo that is found inside BINFO's hierarchy that is
   the same type as the type given in PARENT.  To be optimal, we want
   the first one that is found by going through the least number of
   virtual bases.  */

static tree
get_vbase_1 (parent, binfo, depth)
     tree parent, binfo;
     unsigned int *depth;
{
  tree binfos;
  int i, n_baselinks;
  tree rval = NULL_TREE;

  if (BINFO_TYPE (binfo) == parent && TREE_VIA_VIRTUAL (binfo))
    {
      *depth = 0;
      return binfo;
    }

  *depth = *depth - 1;

  binfos = BINFO_BASETYPES (binfo);
  n_baselinks = binfos ? TREE_VEC_LENGTH (binfos) : 0;

  /* Process base types.  */
  for (i = 0; i < n_baselinks; i++)
    {
      tree base_binfo = TREE_VEC_ELT (binfos, i);
      tree nrval;

      if (*depth == 0)
	break;

      nrval = get_vbase_1 (parent, base_binfo, depth);
      if (nrval)
	rval = nrval;
    }
  *depth = *depth+1;
  return rval;
}

tree
get_vbase (parent, binfo)
     tree parent;
     tree binfo;
{
  unsigned int d = (unsigned int)-1;
  return get_vbase_1 (parent, binfo, &d);
}

/* Convert EXPR to a virtual base class of type TYPE.  We know that
   EXPR is a non-null POINTER_TYPE to RECORD_TYPE.  We also know that
   the type of what expr points to has a virtual base of type TYPE.  */

static tree
convert_pointer_to_vbase (type, expr)
     tree type;
     tree expr;
{
  tree vb = get_vbase (type, TYPE_BINFO (TREE_TYPE (TREE_TYPE (expr))));
  return convert_pointer_to_real (vb, expr);
}

/* Check whether the type given in BINFO is derived from PARENT.  If
   it isn't, return 0.  If it is, but the derivation is MI-ambiguous
   AND protect != 0, emit an error message and return error_mark_node.

   Otherwise, if TYPE is derived from PARENT, return the actual base
   information, unless a one of the protection violations below
   occurs, in which case emit an error message and return error_mark_node.

   If PROTECT is 1, then check if access to a public field of PARENT
   would be private.  Also check for ambiguity.  */

tree
get_binfo (parent, binfo, protect)
     register tree parent, binfo;
     int protect;
{
  tree type;
  int dist;
  tree rval = NULL_TREE;
  
  if (TREE_CODE (parent) == TREE_VEC)
    parent = BINFO_TYPE (parent);
  else if (! IS_AGGR_TYPE_CODE (TREE_CODE (parent)))
    my_friendly_abort (89);

  if (TREE_CODE (binfo) == TREE_VEC)
    type = BINFO_TYPE (binfo);
  else if (IS_AGGR_TYPE_CODE (TREE_CODE (binfo)))
    type = binfo;
  else
    my_friendly_abort (90);
  
  dist = get_base_distance (parent, binfo, protect, &rval);

  if (dist == -3)
    {
      cp_error ("fields of `%T' are inaccessible in `%T' due to private inheritance",
		parent, type);
      return error_mark_node;
    }
  else if (dist == -2 && protect)
    {
      cp_error ("type `%T' is ambiguous base class for type `%T'", parent,
		type);
      return error_mark_node;
    }

  return rval;
}

/* This is the newer depth first get_base_distance routine.  */

static int
get_base_distance_recursive (binfo, depth, is_private, rval,
			     rval_private_ptr, new_binfo_ptr, parent, path_ptr,
			     protect, via_virtual_ptr, via_virtual,
			     current_scope_in_chain)
     tree binfo;
     int depth, is_private, rval;
     int *rval_private_ptr;
     tree *new_binfo_ptr, parent, *path_ptr;
     int protect, *via_virtual_ptr, via_virtual;
     int current_scope_in_chain;
{
  tree binfos;
  int i, n_baselinks;

  if (protect
      && !current_scope_in_chain
      && is_friend (BINFO_TYPE (binfo), current_scope ()))
    current_scope_in_chain = 1;

  if (BINFO_TYPE (binfo) == parent || binfo == parent)
    {
      if (rval == -1)
	{
	  rval = depth;
	  *rval_private_ptr = is_private;
	  *new_binfo_ptr = binfo;
	  *via_virtual_ptr = via_virtual;
	}
      else
	{
	  int same_object = (tree_int_cst_equal (BINFO_OFFSET (*new_binfo_ptr),
						 BINFO_OFFSET (binfo))
			     && *via_virtual_ptr && via_virtual);
			     
	  if (*via_virtual_ptr && via_virtual==0)
	    {
	      *rval_private_ptr = is_private;
	      *new_binfo_ptr = binfo;
	      *via_virtual_ptr = via_virtual;
	    }
	  else if (same_object)
	    {
	      if (*rval_private_ptr && ! is_private)
		{
		  *rval_private_ptr = is_private;
		  *new_binfo_ptr = binfo;
		  *via_virtual_ptr = via_virtual;
		}
	      return rval;
	    }

	  rval = -2;
	}
      return rval;
    }

  binfos = BINFO_BASETYPES (binfo);
  n_baselinks = binfos ? TREE_VEC_LENGTH (binfos) : 0;
  depth += 1;

  /* Process base types.  */
  for (i = 0; i < n_baselinks; i++)
    {
      tree base_binfo = TREE_VEC_ELT (binfos, i);

      /* Find any specific instance of a virtual base, when searching with
	 a binfo...  */
      if (BINFO_MARKED (base_binfo) == 0 || TREE_CODE (parent) == TREE_VEC)
	{
	  int via_private
	    = (protect
	       && (is_private
		   || (!TREE_VIA_PUBLIC (base_binfo)
		       && !(TREE_VIA_PROTECTED (base_binfo)
			    && current_scope_in_chain)
		       && !is_friend (BINFO_TYPE (binfo), current_scope ()))));
	  int this_virtual = via_virtual || TREE_VIA_VIRTUAL (base_binfo);
	  int was;

	  /* When searching for a non-virtual, we cannot mark
	     virtually found binfos.  */
	  if (! this_virtual)
	    SET_BINFO_MARKED (base_binfo);

#define WATCH_VALUES(rval, via_private) (rval == -1 ? 3 : via_private)

	  was = WATCH_VALUES (rval, *via_virtual_ptr);
	  rval = get_base_distance_recursive (base_binfo, depth, via_private,
					      rval, rval_private_ptr,
					      new_binfo_ptr, parent, path_ptr,
					      protect, via_virtual_ptr,
					      this_virtual,
					      current_scope_in_chain);
	  /* watch for updates; only update if path is good.  */
	  if (path_ptr && WATCH_VALUES (rval, *via_virtual_ptr) != was)
	    BINFO_INHERITANCE_CHAIN (base_binfo) = binfo;
	  if (rval == -2 && *via_virtual_ptr == 0)
	    return rval;

#undef WATCH_VALUES

	}
    }

  return rval;
}

/* Return the number of levels between type PARENT and the type given
   in BINFO, following the leftmost path to PARENT not found along a
   virtual path, if there are no real PARENTs (all come from virtual
   base classes), then follow the leftmost path to PARENT.

   Return -1 if TYPE is not derived from PARENT.
   Return -2 if PARENT is an ambiguous base class of TYPE, and PROTECT is
    non-negative.
   Return -3 if PARENT is private to TYPE, and PROTECT is non-zero.

   If PATH_PTR is non-NULL, then also build the list of types
   from PARENT to TYPE, with TREE_VIA_VIRTUAL and TREE_VIA_PUBLIC
   set.

   PARENT can also be a binfo, in which case that exact parent is found
   and no other.  convert_pointer_to_real uses this functionality.

   If BINFO is a binfo, its BINFO_INHERITANCE_CHAIN will be left alone.  */

int
get_base_distance (parent, binfo, protect, path_ptr)
     register tree parent, binfo;
     int protect;
     tree *path_ptr;
{
  int rval;
  int rval_private = 0;
  tree type;
  tree new_binfo = NULL_TREE;
  int via_virtual;
  int watch_access = protect;

  /* Should we be completing types here?  */
  if (TREE_CODE (parent) != TREE_VEC)
    parent = complete_type (TYPE_MAIN_VARIANT (parent));
  else
    complete_type (TREE_TYPE (parent));

  if (TREE_CODE (binfo) == TREE_VEC)
    type = BINFO_TYPE (binfo);
  else if (IS_AGGR_TYPE_CODE (TREE_CODE (binfo)))
    {
      type = complete_type (binfo);
      binfo = TYPE_BINFO (type);

      if (path_ptr)
	BINFO_INHERITANCE_CHAIN (binfo) = NULL_TREE;
    }
  else
    my_friendly_abort (92);

  if (parent == type || parent == binfo)
    {
      /* If the distance is 0, then we don't really need
	 a path pointer, but we shouldn't let garbage go back.  */
      if (path_ptr)
	*path_ptr = binfo;
      return 0;
    }

  if (path_ptr)
    watch_access = 1;

  rval = get_base_distance_recursive (binfo, 0, 0, -1,
				      &rval_private, &new_binfo, parent,
				      path_ptr, watch_access, &via_virtual, 0,
				      0);

  dfs_walk (binfo, dfs_unmark, markedp);

  /* Access restrictions don't count if we found an ambiguous basetype.  */
  if (rval == -2 && protect >= 0)
    rval_private = 0;

  if (rval && protect && rval_private)
    return -3;

  /* find real virtual base classes.  */
  if (rval == -1 && TREE_CODE (parent) == TREE_VEC
      && parent == binfo_member (BINFO_TYPE (parent),
				 CLASSTYPE_VBASECLASSES (type)))
    {
      BINFO_INHERITANCE_CHAIN (parent) = binfo;
      new_binfo = parent;
      rval = 1;
    }

  if (path_ptr)
    *path_ptr = new_binfo;
  return rval;
}

/* Search for a member with name NAME in a multiple inheritance lattice
   specified by TYPE.  If it does not exist, return NULL_TREE.
   If the member is ambiguously referenced, return `error_mark_node'.
   Otherwise, return the FIELD_DECL.  */

/* Do a 1-level search for NAME as a member of TYPE.  The caller must
   figure out whether it can access this field.  (Since it is only one
   level, this is reasonable.)  */

static tree
lookup_field_1 (type, name)
     tree type, name;
{
  register tree field = TYPE_FIELDS (type);

#ifdef GATHER_STATISTICS
  n_calls_lookup_field_1++;
#endif /* GATHER_STATISTICS */
  while (field)
    {
#ifdef GATHER_STATISTICS
      n_fields_searched++;
#endif /* GATHER_STATISTICS */
      if (DECL_NAME (field) == NULL_TREE
	  && TREE_CODE (TREE_TYPE (field)) == UNION_TYPE)
	{
	  tree temp = lookup_field_1 (TREE_TYPE (field), name);
	  if (temp)
	    return temp;
	}
      if (DECL_NAME (field) == name)
	{
	  if ((TREE_CODE(field) == VAR_DECL || TREE_CODE(field) == CONST_DECL)
	      && DECL_ASSEMBLER_NAME (field) != NULL)
	    GNU_xref_ref(current_function_decl,
			 IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (field)));
	  return field;
	}
      field = TREE_CHAIN (field);
    }
  /* Not found.  */
  if (name == _vptr_name)
    {
      /* Give the user what s/he thinks s/he wants.  */
      if (TYPE_VIRTUAL_P (type))
	return CLASSTYPE_VFIELD (type);
    }
  return NULL_TREE;
}

/* There are a number of cases we need to be aware of here:
			 current_class_type	current_function_decl
     global			NULL			NULL
     fn-local			NULL			SET
     class-local		SET			NULL
     class->fn			SET			SET
     fn->class			SET			SET

   Those last two make life interesting.  If we're in a function which is
   itself inside a class, we need decls to go into the fn's decls (our
   second case below).  But if we're in a class and the class itself is
   inside a function, we need decls to go into the decls for the class.  To
   achieve this last goal, we must see if, when both current_class_ptr and
   current_function_decl are set, the class was declared inside that
   function.  If so, we know to put the decls into the class's scope.  */

tree
current_scope ()
{
  if (current_function_decl == NULL_TREE)
    return current_class_type;
  if (current_class_type == NULL_TREE)
    return current_function_decl;
  if (DECL_CLASS_CONTEXT (current_function_decl) == current_class_type)
    return current_function_decl;

  return current_class_type;
}

/* Compute the access of FIELD.  This is done by computing
   the access available to each type in BASETYPES (which comes
   as a list of [via_public/basetype] in reverse order, namely base
   class before derived class).  The first one which defines a
   access defines the access for the field.  Otherwise, the
   access of the field is that which occurs normally.

   Uses global variables CURRENT_CLASS_TYPE and
   CURRENT_FUNCTION_DECL to use friend relationships
   if necessary.

   This will be static when lookup_fnfield comes into this file.

   access_public_node means that the field can be accessed by the current lexical
   scope.

   access_protected_node means that the field cannot be accessed by the current
   lexical scope because it is protected.

   access_private_node means that the field cannot be accessed by the current
   lexical scope because it is private.  */

#if 0
#define PUBLIC_RETURN return (DECL_PUBLIC (field) = 1), access_public_node
#define PROTECTED_RETURN return (DECL_PROTECTED (field) = 1), access_protected_node
#define PRIVATE_RETURN return (DECL_PRIVATE (field) = 1), access_private_node
#else
#define PUBLIC_RETURN return access_public_node
#define PROTECTED_RETURN return access_protected_node
#define PRIVATE_RETURN return access_private_node
#endif

#if 0
/* Disabled with DECL_PUBLIC &c.  */
static tree previous_scope = NULL_TREE;
#endif

tree
compute_access (basetype_path, field)
     tree basetype_path, field;
{
  tree access;
  tree types;
  tree context;