objc-act.c

gcc的组件

  if (!is_ptr)
    {
      type = objc_is_class_name (interface);

      if (type)
	type = xref_tag (RECORD_TYPE, type);
      else
        return interface;
    }

  if (protocols)
    {
      type = build_variant_type_copy (type);

      /* For pointers (i.e., 'id' or 'Class'), attach the protocol(s)
	 to the pointee.  */
      if (is_ptr)
	{
	  TREE_TYPE (type) = build_variant_type_copy (TREE_TYPE (type));
	  TYPE_POINTER_TO (TREE_TYPE (type)) = type;
	  type = TREE_TYPE (type);
	}

      /* Look up protocols and install in lang specific list.  */
      DUP_TYPE_OBJC_INFO (type, TYPE_MAIN_VARIANT (type));
      TYPE_OBJC_PROTOCOL_LIST (type) = lookup_and_install_protocols (protocols);

      /* For RECORD_TYPEs, point to the @interface; for 'id' and 'Class',
	 return the pointer to the new pointee variant.  */
      if (is_ptr)
	type = TYPE_POINTER_TO (type);
      else
	TYPE_OBJC_INTERFACE (type)
	  = TYPE_OBJC_INTERFACE (TYPE_MAIN_VARIANT (type));
    }

  return type;
}

/* Check for circular dependencies in protocols.  The arguments are
   PROTO, the protocol to check, and LIST, a list of protocol it
   conforms to.  */

static void
check_protocol_recursively (tree proto, tree list)
{
  tree p;

  for (p = list; p; p = TREE_CHAIN (p))
    {
      tree pp = TREE_VALUE (p);

      if (TREE_CODE (pp) == IDENTIFIER_NODE)
	pp = lookup_protocol (pp);

      if (pp == proto)
	fatal_error ("protocol %qs has circular dependency",
		     IDENTIFIER_POINTER (PROTOCOL_NAME (pp)));
      if (pp)
	check_protocol_recursively (proto, PROTOCOL_LIST (pp));
    }
}

/* Look up PROTOCOLS, and return a list of those that are found.
   If none are found, return NULL.  */

static tree
lookup_and_install_protocols (tree protocols)
{
  tree proto;
  tree return_value = NULL_TREE;

  for (proto = protocols; proto; proto = TREE_CHAIN (proto))
    {
      tree ident = TREE_VALUE (proto);
      tree p = lookup_protocol (ident);

      if (!p)
	error ("cannot find protocol declaration for %qs",
	       IDENTIFIER_POINTER (ident));
      else
	return_value = chainon (return_value,
				build_tree_list (NULL_TREE, p));
    }

  return return_value;
}

/* Create a declaration for field NAME of a given TYPE.  */

static tree
create_field_decl (tree type, const char *name)
{
  return build_decl (FIELD_DECL, get_identifier (name), type);
}

/* Create a global, static declaration for variable NAME of a given TYPE.  The
   finish_var_decl() routine will need to be called on it afterwards.  */

static tree
start_var_decl (tree type, const char *name)
{
  tree var = build_decl (VAR_DECL, get_identifier (name), type);

  TREE_STATIC (var) = 1;
  DECL_INITIAL (var) = error_mark_node;  /* A real initializer is coming... */
  DECL_IGNORED_P (var) = 1;
  DECL_ARTIFICIAL (var) = 1;
  DECL_CONTEXT (var) = NULL_TREE;
#ifdef OBJCPLUS
  DECL_THIS_STATIC (var) = 1; /* squash redeclaration errors */
#endif

  return var;
}

/* Finish off the variable declaration created by start_var_decl().  */

static void
finish_var_decl (tree var, tree initializer)
{
  finish_decl (var, initializer, NULL_TREE);
  /* Ensure that the variable actually gets output.  */
  mark_decl_referenced (var);
  /* Mark the decl to avoid "defined but not used" warning.  */
  TREE_USED (var) = 1;
}

/* Find the decl for the constant string class reference.  This is only
   used for the NeXT runtime.  */

static tree
setup_string_decl (void)
{
  char *name;
  size_t length;

  /* %s in format will provide room for terminating null */
  length = strlen (STRING_OBJECT_GLOBAL_FORMAT)
	   + strlen (constant_string_class_name);
  name = xmalloc (length);
  sprintf (name, STRING_OBJECT_GLOBAL_FORMAT,
	   constant_string_class_name);
  constant_string_global_id = get_identifier (name);
  string_class_decl = lookup_name (constant_string_global_id);

  return string_class_decl;
}

/* Purpose: "play" parser, creating/installing representations
   of the declarations that are required by Objective-C.

   Model:

	type_spec--------->sc_spec
	(tree_list)        (tree_list)
	    |                  |
	    |                  |
	identifier_node    identifier_node  */

static void
synth_module_prologue (void)
{
  tree type;
  enum debug_info_type save_write_symbols = write_symbols;
  const struct gcc_debug_hooks *const save_hooks = debug_hooks;

  /* Suppress outputting debug symbols, because
     dbxout_init hasn'r been called yet.  */
  write_symbols = NO_DEBUG;
  debug_hooks = &do_nothing_debug_hooks;

#ifdef OBJCPLUS
  push_lang_context (lang_name_c); /* extern "C" */
#endif

  /* The following are also defined in <objc/objc.h> and friends.  */

  objc_object_id = get_identifier (TAG_OBJECT);
  objc_class_id = get_identifier (TAG_CLASS);

  objc_object_reference = xref_tag (RECORD_TYPE, objc_object_id);
  objc_class_reference = xref_tag (RECORD_TYPE, objc_class_id);
  
  objc_object_type = build_pointer_type (objc_object_reference);
  objc_class_type = build_pointer_type (objc_class_reference);

  objc_object_name = get_identifier (OBJECT_TYPEDEF_NAME);
  objc_class_name = get_identifier (CLASS_TYPEDEF_NAME);

  /* Declare the 'id' and 'Class' typedefs.  */

  type = lang_hooks.decls.pushdecl (build_decl (TYPE_DECL,
						objc_object_name,
						objc_object_type));
  DECL_IN_SYSTEM_HEADER (type) = 1;
  type = lang_hooks.decls.pushdecl (build_decl (TYPE_DECL,
						objc_class_name,
						objc_class_type));
  DECL_IN_SYSTEM_HEADER (type) = 1;

  /* Forward-declare '@interface Protocol'.  */

  type = get_identifier (PROTOCOL_OBJECT_CLASS_NAME);
  objc_declare_class (tree_cons (NULL_TREE, type, NULL_TREE));
  objc_protocol_type = build_pointer_type (xref_tag (RECORD_TYPE,
                                type));

  /* Declare type of selector-objects that represent an operation name.  */

  if (flag_next_runtime)
    /* `struct objc_selector *' */
    objc_selector_type
      = build_pointer_type (xref_tag (RECORD_TYPE,
				      get_identifier (TAG_SELECTOR)));
  else
    /* `const struct objc_selector *' */
    objc_selector_type
      = build_pointer_type
	(build_qualified_type (xref_tag (RECORD_TYPE,
					 get_identifier (TAG_SELECTOR)),
			       TYPE_QUAL_CONST));

  /* Declare receiver type used for dispatching messages to 'super'.  */

  /* `struct objc_super *' */
  objc_super_type = build_pointer_type (xref_tag (RECORD_TYPE,
						  get_identifier (TAG_SUPER)));

  /* Declare pointers to method and ivar lists.  */
  objc_method_list_ptr = build_pointer_type
			 (xref_tag (RECORD_TYPE,
				    get_identifier (UTAG_METHOD_LIST)));
  objc_method_proto_list_ptr
    = build_pointer_type (xref_tag (RECORD_TYPE,
				    get_identifier (UTAG_METHOD_PROTOTYPE_LIST)));
  objc_ivar_list_ptr = build_pointer_type
		       (xref_tag (RECORD_TYPE,
				  get_identifier (UTAG_IVAR_LIST)));

  /* TREE_NOTHROW is cleared for the message-sending functions,
     because the function that gets called can throw in Obj-C++, or
     could itself call something that can throw even in Obj-C.  */

  if (flag_next_runtime)
    {
      /* NB: In order to call one of the ..._stret (struct-returning)
      functions, the function *MUST* first be cast to a signature that
      corresponds to the actual ObjC method being invoked.  This is
      what is done by the build_objc_method_call() routine below.  */

      /* id objc_msgSend (id, SEL, ...); */
      /* id objc_msgSendNonNil (id, SEL, ...); */
      /* id objc_msgSend_stret (id, SEL, ...); */
      /* id objc_msgSendNonNil_stret (id, SEL, ...); */
      type
	= build_function_type (objc_object_type,
			       tree_cons (NULL_TREE, objc_object_type,
					  tree_cons (NULL_TREE, objc_selector_type,
						     NULL_TREE)));
      umsg_decl = builtin_function (TAG_MSGSEND,
				    type, 0, NOT_BUILT_IN,
				    NULL, NULL_TREE);
      umsg_nonnil_decl = builtin_function (TAG_MSGSEND_NONNIL,
					   type, 0, NOT_BUILT_IN,
					   NULL, NULL_TREE);
      umsg_stret_decl = builtin_function (TAG_MSGSEND_STRET,
					  type, 0, NOT_BUILT_IN,
					  NULL, NULL_TREE);
      umsg_nonnil_stret_decl = builtin_function (TAG_MSGSEND_NONNIL_STRET,
						 type, 0, NOT_BUILT_IN,
						 NULL, NULL_TREE);

      /* These can throw, because the function that gets called can throw
	 in Obj-C++, or could itself call something that can throw even
	 in Obj-C.  */
      TREE_NOTHROW (umsg_decl) = 0;
      TREE_NOTHROW (umsg_nonnil_decl) = 0;
      TREE_NOTHROW (umsg_stret_decl) = 0;
      TREE_NOTHROW (umsg_nonnil_stret_decl) = 0;

      /* id objc_msgSend_Fast (id, SEL, ...)
	   __attribute__ ((hard_coded_address (OFFS_MSGSEND_FAST))); */
#ifdef OFFS_MSGSEND_FAST
      umsg_fast_decl = builtin_function (TAG_MSGSEND_FAST,
					 type, 0, NOT_BUILT_IN,
					 NULL, NULL_TREE);
      TREE_NOTHROW (umsg_fast_decl) = 0;
      DECL_ATTRIBUTES (umsg_fast_decl) 
	= tree_cons (get_identifier ("hard_coded_address"), 
		     build_int_cst (NULL_TREE, OFFS_MSGSEND_FAST),
		     NULL_TREE);
#else
      /* No direct dispatch availible.  */
      umsg_fast_decl = umsg_decl;
#endif

      /* id objc_msgSendSuper (struct objc_super *, SEL, ...); */
      /* id objc_msgSendSuper_stret (struct objc_super *, SEL, ...); */
      type
	= build_function_type (objc_object_type,
			       tree_cons (NULL_TREE, objc_super_type,
					  tree_cons (NULL_TREE, objc_selector_type,
						     NULL_TREE)));
      umsg_super_decl = builtin_function (TAG_MSGSENDSUPER,
					  type, 0, NOT_BUILT_IN,
					  NULL, NULL_TREE);
      umsg_super_stret_decl = builtin_function (TAG_MSGSENDSUPER_STRET,
						type, 0, NOT_BUILT_IN, 0,
						NULL_TREE);
      TREE_NOTHROW (umsg_super_decl) = 0;
      TREE_NOTHROW (umsg_super_stret_decl) = 0;
    }
  else
    {
      /* GNU runtime messenger entry points.  */

      /* typedef id (*IMP)(id, SEL, ...); */
      tree IMP_type
	= build_pointer_type
	  (build_function_type (objc_object_type,      
				tree_cons (NULL_TREE, objc_object_type,      
					   tree_cons (NULL_TREE, objc_selector_type,      
						      NULL_TREE))));      

      /* IMP objc_msg_lookup (id, SEL); */
      type
        = build_function_type (IMP_type,
			       tree_cons (NULL_TREE, objc_object_type,
					  tree_cons (NULL_TREE, objc_selector_type,
						     OBJC_VOID_AT_END)));
      umsg_decl = builtin_function (TAG_MSGSEND,
				    type, 0, NOT_BUILT_IN,
				    NULL, NULL_TREE);
      TREE_NOTHROW (umsg_decl) = 0;

      /* IMP objc_msg_lookup_super (struct objc_super *, SEL); */
      type
        = build_function_type (IMP_type,
			       tree_cons (NULL_TREE, objc_super_type,
					  tree_cons (NULL_TREE, objc_selector_type,
						     OBJC_VOID_AT_END)));
      umsg_super_decl = builtin_function (TAG_MSGSENDSUPER,
					  type, 0, NOT_BUILT_IN,
					  NULL, NULL_TREE);
      TREE_NOTHROW (umsg_super_decl) = 0;

      /* The following GNU runtime entry point is called to initialize
	 each module:

	 __objc_exec_class (void *); */
      type
	= build_function_type (void_type_node,
			       tree_cons (NULL_TREE, ptr_type_node,
					  OBJC_VOID_AT_END));
      execclass_decl = builtin_function (TAG_EXECCLASS,
					 type, 0, NOT_BUILT_IN,
					 NULL, NULL_TREE);
    }

  /* id objc_getClass (const char *); */

  type = build_function_type (objc_object_type,
				   tree_cons (NULL_TREE,
					      const_string_type_node,
					      OBJC_VOID_AT_END));

  objc_get_class_decl
    = builtin_function (TAG_GETCLASS, type, 0, NOT_BUILT_IN,
			NULL, NULL_TREE);

  /* id objc_getMetaClass (const char *); */

  objc_get_meta_class_decl
    = builtin_function (TAG_GETMETACLASS, type, 0, NOT_BUILT_IN, NULL, NULL_TREE);

  build_class_template ();
  build_super_template ();
  build_protocol_template ();
  build_category_template ();
  build_objc_exception_stuff ();

  if (flag_next_runtime)
    build_next_objc_exception_stuff ();

  /* static SEL _OBJC_SELECTOR_TABLE[]; */

  if (! flag_next_runtime)
    build_selector_table_decl ();

  /* Forward declare constant_string_id and constant_string_type.  */
  if (!constant_string_class_name)
    constant_string_class_name = default_constant_string_class_name;

  constant_string_id = get_identifier (constant_string_class_name);
  objc_declare_class (tree_cons (NULL_TREE, constant_string_id, NULL_TREE));

  /* Pre-build the following entities - for speed/convenience.  */
  self_id = get_identifier ("self");
  ucmd_id = get_identifier ("_cmd");

#ifdef OBJCPLUS
  pop_lang_context ();
#endif

  write_symbols = save_write_symbols;
  debug_hooks = save_hooks;
}

/* Ensure that the ivar list for NSConstantString/NXConstantString
   (or whatever was specified via `-fconstant-string-class')
   contains fields at least as large as the following three, so that
   the runtime can stomp on them with confidence:

   struct STRING_OBJECT_CLASS_NAME
   {
     Object isa;
     char *cString;
     unsigned int length;
   }; */

static int
check_string_class_template (void)
{
  tree field_decl = objc_get_class_ivars (constant_string_id);

#define AT_LEAST_AS_LARGE_AS(F, T) \
  (F && TREE_CODE (F) == FIELD_DECL \
     && (TREE_INT_CST_LOW (TYPE_SIZE (TREE_TYPE (F))) \
	 >= TREE_INT_CST_LOW (TYPE_SIZE (T))))

  if (!AT_LEAST_AS_LARGE_AS (field_decl, ptr_type_node))
    return 0;

  field_decl = TREE_CHAIN (field_decl);
  if (!AT_LEAST_AS_LARGE_AS (field_decl, ptr_type_node))
    return 0;

  field_decl = TREE_CHAIN (field_decl);
  return AT_LEAST_AS_LARGE_AS (field_decl, unsigned_type_node);

#undef AT_LEAST_AS_LARGE_AS
}

/* Avoid calling `check_string_class_template ()' more than once.  */
static GTY(()) int string_layout_checked;

/* Construct an internal string layout to be used as a template for
   creating NSConstantString/NXConstantString instances.  */

static tree
objc_build_internal_const_str_type (void)
{