objc-act.c

gcc的组件

      /* Everything matches up!  */
      return t;
    }

  /* Ok, we could not re-use any of the pre-existing variants.  Create
     a new one.  */
  t = build_variant_type_copy (type);
  TYPE_VOLATILE (t) = 1;
  
  return t;
}

/* Mark DECL as being 'volatile' for purposes of Darwin
   _setjmp()/_longjmp() exception handling.  Called from
   objc_mark_locals_volatile().  */
void
objc_volatilize_decl (tree decl)
{
  /* Do not mess with variables that are 'static' or (already)
     'volatile'.  */
  if (!TREE_THIS_VOLATILE (decl) && !TREE_STATIC (decl)
      && (TREE_CODE (decl) == VAR_DECL
	  || TREE_CODE (decl) == PARM_DECL))
    {
      tree t = TREE_TYPE (decl);
      struct volatilized_type key;
      void **loc;

      t = objc_build_volatilized_type (t);
      key.type = t;
      loc = htab_find_slot (volatilized_htab, &key, INSERT);

      if (!*loc)
	{
	  *loc = ggc_alloc (sizeof (key));
	  ((struct volatilized_type *) *loc)->type = t;
	}

      TREE_TYPE (decl) = t;
      TREE_THIS_VOLATILE (decl) = 1;
      TREE_SIDE_EFFECTS (decl) = 1;
      DECL_REGISTER (decl) = 0;
#ifndef OBJCPLUS
      C_DECL_REGISTER (decl) = 0;
#endif
    }
}

/* Check if protocol PROTO is adopted (directly or indirectly) by class CLS
   (including its categoreis and superclasses) or by object type TYP.
   Issue a warning if PROTO is not adopted anywhere and WARN is set.  */

static bool
objc_lookup_protocol (tree proto, tree cls, tree typ, bool warn)
{
  bool class_type = (cls != NULL_TREE);

  while (cls)
    {
      tree c;

      /* Check protocols adopted by the class and its categories.  */
      for (c = cls; c; c = CLASS_CATEGORY_LIST (c))
	{
	  if (lookup_protocol_in_reflist (CLASS_PROTOCOL_LIST (c), proto))
	    return true;
	}

      /* Repeat for superclasses.  */
      cls = lookup_interface (CLASS_SUPER_NAME (cls));
    }

  /* Check for any protocols attached directly to the object type.  */
  if (TYPE_HAS_OBJC_INFO (typ))
    {
      if (lookup_protocol_in_reflist (TYPE_OBJC_PROTOCOL_LIST (typ), proto))
	return true;
    }

  if (warn)
    {
      strcpy (errbuf, class_type ? "class \'" : "type \'");
      gen_type_name_0 (class_type ? typ : TYPE_POINTER_TO (typ));
      strcat (errbuf, "\' does not ");
      /* NB: Types 'id' and 'Class' cannot reasonably be described as
	 "implementing" a given protocol, since they do not have an
	 implementation.  */
      strcat (errbuf, class_type ? "implement" : "conform to");
      strcat (errbuf, " the \'");
      strcat (errbuf, IDENTIFIER_POINTER (PROTOCOL_NAME (proto)));
      strcat (errbuf, "\' protocol");
      warning (0, errbuf);
    }

  return false;
}

/* Check if class RCLS and instance struct type RTYP conform to at least the
   same protocols that LCLS and LTYP conform to.  */

static bool
objc_compare_protocols (tree lcls, tree ltyp, tree rcls, tree rtyp, bool warn)
{
  tree p;
  bool have_lproto = false;

  while (lcls)
    {
      /* NB: We do _not_ look at categories defined for LCLS; these may or
	 may not get loaded in, and therefore it is unreasonable to require
	 that RCLS/RTYP must implement any of their protocols.  */
      for (p = CLASS_PROTOCOL_LIST (lcls); p; p = TREE_CHAIN (p))
	{
	  have_lproto = true;

	  if (!objc_lookup_protocol (TREE_VALUE (p), rcls, rtyp, warn))
	    return warn;
	}

      /* Repeat for superclasses.  */
      lcls = lookup_interface (CLASS_SUPER_NAME (lcls));
    }

  /* Check for any protocols attached directly to the object type.  */
  if (TYPE_HAS_OBJC_INFO (ltyp))
    {
      for (p = TYPE_OBJC_PROTOCOL_LIST (ltyp); p; p = TREE_CHAIN (p))
	{
	  have_lproto = true;

	  if (!objc_lookup_protocol (TREE_VALUE (p), rcls, rtyp, warn))
	    return warn;
	}
    }

  /* NB: If LTYP and LCLS have no protocols to search for, return 'true'
     vacuously, _unless_ RTYP is a protocol-qualified 'id'.  We can get
     away with simply checking for 'id' or 'Class' (!RCLS), since this
     routine will not get called in other cases.  */
  return have_lproto || (rcls != NULL_TREE);
}

/* Determine if it is permissible to assign (if ARGNO is greater than -3)
   an instance of RTYP to an instance of LTYP or to compare the two
   (if ARGNO is equal to -3), per ObjC type system rules.  Before
   returning 'true', this routine may issue warnings related to, e.g.,
   protocol conformance.  When returning 'false', the routine must
   produce absolutely no warnings; the C or C++ front-end will do so
   instead, if needed.  If either LTYP or RTYP is not an Objective-C type,
   the routine must return 'false'.

   The ARGNO parameter is encoded as follows:
     >= 1	Parameter number (CALLEE contains function being called);
     0		Return value;
     -1		Assignment;
     -2		Initialization;
     -3		Comparison (LTYP and RTYP may match in either direction).  */

bool
objc_compare_types (tree ltyp, tree rtyp, int argno, tree callee)
{
  tree lcls, rcls, lproto, rproto;
  bool pointers_compatible;

  /* We must be dealing with pointer types */
  if (!POINTER_TYPE_P (ltyp) || !POINTER_TYPE_P (rtyp))
    return false;

  do
    {
      ltyp = TREE_TYPE (ltyp);  /* Remove indirections.  */
      rtyp = TREE_TYPE (rtyp);
    }
  while (POINTER_TYPE_P (ltyp) && POINTER_TYPE_P (rtyp));

  /* Past this point, we are only interested in ObjC class instances,
     or 'id' or 'Class'.  */
  if (TREE_CODE (ltyp) != RECORD_TYPE || TREE_CODE (rtyp) != RECORD_TYPE)
    return false;

  if (!objc_is_object_id (ltyp) && !objc_is_class_id (ltyp)
      && !TYPE_HAS_OBJC_INFO (ltyp))
    return false;

  if (!objc_is_object_id (rtyp) && !objc_is_class_id (rtyp)
      && !TYPE_HAS_OBJC_INFO (rtyp))
    return false;

  /* Past this point, we are committed to returning 'true' to the caller.
     However, we can still warn about type and/or protocol mismatches.  */

  if (TYPE_HAS_OBJC_INFO (ltyp))
    {
      lcls = TYPE_OBJC_INTERFACE (ltyp);
      lproto = TYPE_OBJC_PROTOCOL_LIST (ltyp);
    }
  else
    lcls = lproto = NULL_TREE;

  if (TYPE_HAS_OBJC_INFO (rtyp))
    {
      rcls = TYPE_OBJC_INTERFACE (rtyp);
      rproto = TYPE_OBJC_PROTOCOL_LIST (rtyp);
    }
  else
    rcls = rproto = NULL_TREE;

  /* If we could not find an @interface declaration, we must have
     only seen a @class declaration; for purposes of type comparison,
     treat it as a stand-alone (root) class.  */

  if (lcls && TREE_CODE (lcls) == IDENTIFIER_NODE)
    lcls = NULL_TREE;

  if (rcls && TREE_CODE (rcls) == IDENTIFIER_NODE)
    rcls = NULL_TREE;

  /* If either type is an unqualified 'id', we're done.  */
  if ((!lproto && objc_is_object_id (ltyp))
      || (!rproto && objc_is_object_id (rtyp)))
    return true;

  pointers_compatible = (TYPE_MAIN_VARIANT (ltyp) == TYPE_MAIN_VARIANT (rtyp));

  /* If the underlying types are the same, and at most one of them has
     a protocol list, we do not need to issue any diagnostics.  */
  if (pointers_compatible && (!lproto || !rproto))
    return true;

  /* If exactly one of the types is 'Class', issue a diagnostic; any
     exceptions of this rule have already been handled.  */
  if (objc_is_class_id (ltyp) ^ objc_is_class_id (rtyp))
    pointers_compatible = false;
  /* Otherwise, check for inheritance relations.  */
  else
    {
      if (!pointers_compatible)
	pointers_compatible
	  = (objc_is_object_id (ltyp) || objc_is_object_id (rtyp));

      if (!pointers_compatible)
	pointers_compatible = DERIVED_FROM_P (ltyp, rtyp);

      if (!pointers_compatible && argno == -3)
	pointers_compatible = DERIVED_FROM_P (rtyp, ltyp);
    }

  /* If the pointers match modulo protocols, check for protocol conformance
     mismatches.  */
  if (pointers_compatible)
    {
      pointers_compatible = objc_compare_protocols (lcls, ltyp, rcls, rtyp,
						    argno != -3);

      if (!pointers_compatible && argno == -3)
	pointers_compatible = objc_compare_protocols (rcls, rtyp, lcls, ltyp,
						      argno != -3);
    }

  if (!pointers_compatible)
    {
      /* NB: For the time being, we shall make our warnings look like their
	 C counterparts.  In the future, we may wish to make them more
	 ObjC-specific.  */
      switch (argno)
	{
	case -3:
	  warning (0, "comparison of distinct Objective-C types lacks a cast");
	  break;

	case -2:
	  warning (0, "initialization from distinct Objective-C type");
	  break;

	case -1:
	  warning (0, "assignment from distinct Objective-C type");
	  break;

	case 0:
	  warning (0, "distinct Objective-C type in return");
	  break;

	default:
	  warning (0, "passing argument %d of %qE from distinct "
		   "Objective-C type", argno, callee);
	  break;
	}
    }

  return true;
}

/* Check if LTYP and RTYP have the same type qualifiers.  If either type
   lives in the volatilized hash table, ignore the 'volatile' bit when
   making the comparison.  */

bool
objc_type_quals_match (tree ltyp, tree rtyp)
{
  int lquals = TYPE_QUALS (ltyp), rquals = TYPE_QUALS (rtyp);
  struct volatilized_type key;

  key.type = ltyp;

  if (htab_find_slot (volatilized_htab, &key, NO_INSERT))
    lquals &= ~TYPE_QUAL_VOLATILE;

  key.type = rtyp;

  if (htab_find_slot (volatilized_htab, &key, NO_INSERT))
    rquals &= ~TYPE_QUAL_VOLATILE;

  return (lquals == rquals);
}

#ifndef OBJCPLUS
/* Determine if CHILD is derived from PARENT.  The routine assumes that
   both parameters are RECORD_TYPEs, and is non-reflexive.  */

static bool
objc_derived_from_p (tree parent, tree child)
{
  parent = TYPE_MAIN_VARIANT (parent);

  for (child = TYPE_MAIN_VARIANT (child);
       TYPE_BINFO (child) && BINFO_N_BASE_BINFOS (TYPE_BINFO (child));)
    {
      child = TYPE_MAIN_VARIANT (BINFO_TYPE (BINFO_BASE_BINFO
					     (TYPE_BINFO (child),
					      0)));

      if (child == parent)
	return true;
    }

  return false;
}
#endif

static tree
objc_build_component_ref (tree datum, tree component)
{
  /* If COMPONENT is NULL, the caller is referring to the anonymous
     base class field.  */
  if (!component)
    {
      tree base = TYPE_FIELDS (TREE_TYPE (datum));

      return build3 (COMPONENT_REF, TREE_TYPE (base), datum, base, NULL_TREE);
    }

  /* The 'build_component_ref' routine has been removed from the C++
     front-end, but 'finish_class_member_access_expr' seems to be
     a worthy substitute.  */
#ifdef OBJCPLUS
  return finish_class_member_access_expr (datum, component, false);
#else
  return build_component_ref (datum, component);
#endif
}

/* Recursively copy inheritance information rooted at BINFO.  To do this,
   we emulate the song and dance performed by cp/tree.c:copy_binfo().  */

static tree
objc_copy_binfo (tree binfo)
{
  tree btype = BINFO_TYPE (binfo);
  tree binfo2 = make_tree_binfo (BINFO_N_BASE_BINFOS (binfo));
  tree base_binfo;
  int ix;

  BINFO_TYPE (binfo2) = btype;
  BINFO_OFFSET (binfo2) = BINFO_OFFSET (binfo);
  BINFO_BASE_ACCESSES (binfo2) = BINFO_BASE_ACCESSES (binfo);

  /* Recursively copy base binfos of BINFO.  */
  for (ix = 0; BINFO_BASE_ITERATE (binfo, ix, base_binfo); ix++)
    {
      tree base_binfo2 = objc_copy_binfo (base_binfo);

      BINFO_INHERITANCE_CHAIN (base_binfo2) = binfo2;
      BINFO_BASE_APPEND (binfo2, base_binfo2);
    }

  return binfo2;
}

/* Record superclass information provided in BASETYPE for ObjC class REF.
   This is loosely based on cp/decl.c:xref_basetypes().  */

static void
objc_xref_basetypes (tree ref, tree basetype)
{
  tree binfo = make_tree_binfo (basetype ? 1 : 0);

  TYPE_BINFO (ref) = binfo;
  BINFO_OFFSET (binfo) = size_zero_node;
  BINFO_TYPE (binfo) = ref;

  if (basetype)
    {
      tree base_binfo = objc_copy_binfo (TYPE_BINFO (basetype));

      BINFO_INHERITANCE_CHAIN (base_binfo) = binfo;
      BINFO_BASE_ACCESSES (binfo) = VEC_alloc (tree, gc, 1);
      BINFO_BASE_APPEND (binfo, base_binfo);
      BINFO_BASE_ACCESS_APPEND (binfo, access_public_node);
    }
}

static hashval_t
volatilized_hash (const void *ptr)
{
  tree typ = ((struct volatilized_type *)ptr)->type;

  return htab_hash_pointer(typ);
}

static int
volatilized_eq (const void *ptr1, const void *ptr2)
{
  tree typ1 = ((struct volatilized_type *)ptr1)->type;
  tree typ2 = ((struct volatilized_type *)ptr2)->type;

  return typ1 == typ2;
}

/* Called from finish_decl.  */

void
objc_check_decl (tree decl)
{
  tree type = TREE_TYPE (decl);

  if (TREE_CODE (type) != RECORD_TYPE)
    return;
  if (OBJC_TYPE_NAME (type) && (type = objc_is_class_name (OBJC_TYPE_NAME (type))))
    error ("statically allocated instance of Objective-C class %qs",
	   IDENTIFIER_POINTER (type));
}

/* Construct a PROTOCOLS-qualified variant of INTERFACE, where INTERFACE may
   either name an Objective-C class, or refer to the special 'id' or 'Class'
   types.  If INTERFACE is not a valid ObjC type, just return it unchanged.  */

tree
objc_get_protocol_qualified_type (tree interface, tree protocols)
{
  /* If INTERFACE is not provided, default to 'id'.  */
  tree type = (interface ? objc_is_id (interface) : objc_object_type);
  bool is_ptr = (type != NULL_TREE);