objc-act.c

gcc的组件

  tree type = (*lang_hooks.types.make_type) (RECORD_TYPE);
  tree fields = build_decl (FIELD_DECL, NULL_TREE, ptr_type_node);
  tree field = build_decl (FIELD_DECL, NULL_TREE, ptr_type_node);

  TREE_CHAIN (field) = fields; fields = field;
  field = build_decl (FIELD_DECL, NULL_TREE, unsigned_type_node);
  TREE_CHAIN (field) = fields; fields = field;
  /* NB: The finish_builtin_struct() routine expects FIELD_DECLs in
     reverse order!  */
  finish_builtin_struct (type, "__builtin_ObjCString",
			 fields, NULL_TREE);

  return type;
}

/* Custom build_string which sets TREE_TYPE!  */

static tree
my_build_string (int len, const char *str)
{
  return fix_string_type (build_string (len, str));
}

/* Build a string with contents STR and length LEN and convert it to a
   pointer.  */

static tree
my_build_string_pointer (int len, const char *str)
{
  tree string = my_build_string (len, str);
  tree ptrtype = build_pointer_type (TREE_TYPE (TREE_TYPE (string)));
  return build1 (ADDR_EXPR, ptrtype, string);
}

static hashval_t
string_hash (const void *ptr)
{
  tree str = ((struct string_descriptor *)ptr)->literal;
  const unsigned char *p = (const unsigned char *) TREE_STRING_POINTER (str);
  int i, len = TREE_STRING_LENGTH (str);
  hashval_t h = len;

  for (i = 0; i < len; i++)
    h = ((h * 613) + p[i]);

  return h;
}

static int
string_eq (const void *ptr1, const void *ptr2)
{
  tree str1 = ((struct string_descriptor *)ptr1)->literal;
  tree str2 = ((struct string_descriptor *)ptr2)->literal;
  int len1 = TREE_STRING_LENGTH (str1);

  return (len1 == TREE_STRING_LENGTH (str2)
	  && !memcmp (TREE_STRING_POINTER (str1), TREE_STRING_POINTER (str2),
		      len1));
}

/* Given a chain of STRING_CST's, build a static instance of
   NXConstantString which points at the concatenation of those
   strings.  We place the string object in the __string_objects
   section of the __OBJC segment.  The Objective-C runtime will
   initialize the isa pointers of the string objects to point at the
   NXConstantString class object.  */

tree
objc_build_string_object (tree string)
{
  tree initlist, constructor, constant_string_class;
  int length;
  tree fields, addr;
  struct string_descriptor *desc, key;
  void **loc;

  /* Prep the string argument.  */
  string = fix_string_type (string);
  TREE_SET_CODE (string, STRING_CST);
  length = TREE_STRING_LENGTH (string) - 1;

  /* Check whether the string class being used actually exists and has the
     correct ivar layout.  */
  if (!string_layout_checked)
    {
      string_layout_checked = -1;
      constant_string_class = lookup_interface (constant_string_id);
      internal_const_str_type = objc_build_internal_const_str_type ();

      if (!constant_string_class
	  || !(constant_string_type
	       = CLASS_STATIC_TEMPLATE (constant_string_class)))
	error ("cannot find interface declaration for %qs",
	       IDENTIFIER_POINTER (constant_string_id));
      /* The NSConstantString/NXConstantString ivar layout is now known.  */
      else if (!check_string_class_template ())
	error ("interface %qs does not have valid constant string layout",
	       IDENTIFIER_POINTER (constant_string_id));
      /* For the NeXT runtime, we can generate a literal reference
	 to the string class, don't need to run a constructor.  */
      else if (flag_next_runtime && !setup_string_decl ())
	error ("cannot find reference tag for class %qs",
	       IDENTIFIER_POINTER (constant_string_id));
      else
	{
	  string_layout_checked = 1;  /* Success!  */
	  add_class_reference (constant_string_id);
	}
    }

  if (string_layout_checked == -1)
    return error_mark_node;

  /* Perhaps we already constructed a constant string just like this one? */
  key.literal = string;
  loc = htab_find_slot (string_htab, &key, INSERT);
  desc = *loc;

  if (!desc)
    {
      tree var;
      *loc = desc = ggc_alloc (sizeof (*desc));
      desc->literal = string;

      /* GNU:    (NXConstantString *) & ((__builtin_ObjCString) { NULL, string, length })  */
      /* NeXT:   (NSConstantString *) & ((__builtin_ObjCString) { isa, string, length })   */
      fields = TYPE_FIELDS (internal_const_str_type);
      initlist
	= build_tree_list (fields,
			   flag_next_runtime
			   ? build_unary_op (ADDR_EXPR, string_class_decl, 0)
			   : build_int_cst (NULL_TREE, 0));
      fields = TREE_CHAIN (fields);
      initlist = tree_cons (fields, build_unary_op (ADDR_EXPR, string, 1),
			    initlist);
      fields = TREE_CHAIN (fields);
      initlist = tree_cons (fields, build_int_cst (NULL_TREE, length),
 			    initlist);
      constructor = objc_build_constructor (internal_const_str_type,
					    nreverse (initlist));
      TREE_INVARIANT (constructor) = true;

      if (!flag_next_runtime)
	constructor
	  = objc_add_static_instance (constructor, constant_string_type);
      else
        {
	  var = build_decl (CONST_DECL, NULL, TREE_TYPE (constructor));
	  DECL_INITIAL (var) = constructor;
	  TREE_STATIC (var) = 1;
	  pushdecl_top_level (var);
	  constructor = var;
	}
      desc->constructor = constructor;
    }

  addr = convert (build_pointer_type (constant_string_type),
		  build_unary_op (ADDR_EXPR, desc->constructor, 1));

  return addr;
}

/* Declare a static instance of CLASS_DECL initialized by CONSTRUCTOR.  */

static GTY(()) int num_static_inst;

static tree
objc_add_static_instance (tree constructor, tree class_decl)
{
  tree *chain, decl;
  char buf[256];

  /* Find the list of static instances for the CLASS_DECL.  Create one if
     not found.  */
  for (chain = &objc_static_instances;
       *chain && TREE_VALUE (*chain) != class_decl;
       chain = &TREE_CHAIN (*chain));
  if (!*chain)
    {
      *chain = tree_cons (NULL_TREE, class_decl, NULL_TREE);
      add_objc_string (OBJC_TYPE_NAME (class_decl), class_names);
    }

  sprintf (buf, "_OBJC_INSTANCE_%d", num_static_inst++);
  decl = build_decl (VAR_DECL, get_identifier (buf), class_decl);
  DECL_COMMON (decl) = 1;
  TREE_STATIC (decl) = 1;
  DECL_ARTIFICIAL (decl) = 1;
  DECL_INITIAL (decl) = constructor;

  /* We may be writing something else just now.
     Postpone till end of input.  */
  DECL_DEFER_OUTPUT (decl) = 1;
  pushdecl_top_level (decl);
  rest_of_decl_compilation (decl, 1, 0);

  /* Add the DECL to the head of this CLASS' list.  */
  TREE_PURPOSE (*chain) = tree_cons (NULL_TREE, decl, TREE_PURPOSE (*chain));

  return decl;
}

/* Build a static constant CONSTRUCTOR
   with type TYPE and elements ELTS.  */

static tree
objc_build_constructor (tree type, tree elts)
{
  tree constructor = build_constructor_from_list (type, elts);

  TREE_CONSTANT (constructor) = 1;
  TREE_STATIC (constructor) = 1;
  TREE_READONLY (constructor) = 1;

#ifdef OBJCPLUS
  /* Adjust for impedance mismatch.  We should figure out how to build
     CONSTRUCTORs that consistently please both the C and C++ gods.  */
  if (!TREE_PURPOSE (elts))
    TREE_TYPE (constructor) = NULL_TREE;
  TREE_HAS_CONSTRUCTOR (constructor) = 1;
#endif

  return constructor;
}

/* Take care of defining and initializing _OBJC_SYMBOLS.  */

/* Predefine the following data type:

   struct _objc_symtab
   {
     long sel_ref_cnt;
     SEL *refs;
     short cls_def_cnt;
     short cat_def_cnt;
     void *defs[cls_def_cnt + cat_def_cnt];
   }; */

static void
build_objc_symtab_template (void)
{
  tree field_decl, field_decl_chain;

  objc_symtab_template
    = start_struct (RECORD_TYPE, get_identifier (UTAG_SYMTAB));

  /* long sel_ref_cnt; */
  field_decl = create_field_decl (long_integer_type_node, "sel_ref_cnt");
  field_decl_chain = field_decl;

  /* SEL *refs; */
  field_decl = create_field_decl (build_pointer_type (objc_selector_type),
				  "refs");
  chainon (field_decl_chain, field_decl);

  /* short cls_def_cnt; */
  field_decl = create_field_decl (short_integer_type_node, "cls_def_cnt");
  chainon (field_decl_chain, field_decl);

  /* short cat_def_cnt; */
  field_decl = create_field_decl (short_integer_type_node,
				  "cat_def_cnt");
  chainon (field_decl_chain, field_decl);

  if (imp_count || cat_count || !flag_next_runtime)
    {
      /* void *defs[imp_count + cat_count (+ 1)]; */
      /* NB: The index is one less than the size of the array.  */
      int index = imp_count + cat_count
		+ (flag_next_runtime? -1: 0);
      field_decl = create_field_decl
		   (build_array_type
		    (ptr_type_node,
		     build_index_type (build_int_cst (NULL_TREE, index))),
		    "defs");
      chainon (field_decl_chain, field_decl);
    }

  finish_struct (objc_symtab_template, field_decl_chain, NULL_TREE);
}

/* Create the initial value for the `defs' field of _objc_symtab.
   This is a CONSTRUCTOR.  */

static tree
init_def_list (tree type)
{
  tree expr, initlist = NULL_TREE;
  struct imp_entry *impent;

  if (imp_count)
    for (impent = imp_list; impent; impent = impent->next)
      {
	if (TREE_CODE (impent->imp_context) == CLASS_IMPLEMENTATION_TYPE)
	  {
	    expr = build_unary_op (ADDR_EXPR, impent->class_decl, 0);
	    initlist = tree_cons (NULL_TREE, expr, initlist);
	  }
      }

  if (cat_count)
    for (impent = imp_list; impent; impent = impent->next)
      {
	if (TREE_CODE (impent->imp_context) == CATEGORY_IMPLEMENTATION_TYPE)
	  {
	    expr = build_unary_op (ADDR_EXPR, impent->class_decl, 0);
	    initlist = tree_cons (NULL_TREE, expr, initlist);
	  }
      }

  if (!flag_next_runtime)
    {
      /* statics = { ..., _OBJC_STATIC_INSTANCES, ... }  */
      tree expr;

      if (static_instances_decl)
	expr = build_unary_op (ADDR_EXPR, static_instances_decl, 0);
      else
	expr = build_int_cst (NULL_TREE, 0);

      initlist = tree_cons (NULL_TREE, expr, initlist);
    }

  return objc_build_constructor (type, nreverse (initlist));
}

/* Construct the initial value for all of _objc_symtab.  */

static tree
init_objc_symtab (tree type)
{
  tree initlist;

  /* sel_ref_cnt = { ..., 5, ... } */

  initlist = build_tree_list (NULL_TREE,
			      build_int_cst (long_integer_type_node, 0));

  /* refs = { ..., _OBJC_SELECTOR_TABLE, ... } */

  if (flag_next_runtime || ! sel_ref_chain)
    initlist = tree_cons (NULL_TREE, build_int_cst (NULL_TREE, 0), initlist);
  else
    initlist
      = tree_cons (NULL_TREE,
		   convert (build_pointer_type (objc_selector_type),
			    build_unary_op (ADDR_EXPR,
					    UOBJC_SELECTOR_TABLE_decl, 1)),
		   initlist);

  /* cls_def_cnt = { ..., 5, ... } */

  initlist = tree_cons (NULL_TREE, build_int_cst (NULL_TREE, imp_count), initlist);

  /* cat_def_cnt = { ..., 5, ... } */

  initlist = tree_cons (NULL_TREE, build_int_cst (NULL_TREE, cat_count), initlist);

  /* cls_def = { ..., { &Foo, &Bar, ...}, ... } */

  if (imp_count || cat_count || !flag_next_runtime)
    {

      tree field = TYPE_FIELDS (type);
      field = TREE_CHAIN (TREE_CHAIN (TREE_CHAIN (TREE_CHAIN (field))));

      initlist = tree_cons (NULL_TREE, init_def_list (TREE_TYPE (field)),
			    initlist);
    }

  return objc_build_constructor (type, nreverse (initlist));
}

/* Generate forward declarations for metadata such as
  'OBJC_CLASS_...'.  */

static tree
build_metadata_decl (const char *name, tree type)
{
  tree decl;

  /* struct TYPE NAME_<name>; */
  decl = start_var_decl (type, synth_id_with_class_suffix
			       (name,
				objc_implementation_context));

  return decl;
}

/* Push forward-declarations of all the categories so that
   init_def_list can use them in a CONSTRUCTOR.  */

static void
forward_declare_categories (void)
{
  struct imp_entry *impent;
  tree sav = objc_implementation_context;

  for (impent = imp_list; impent; impent = impent->next)
    {
      if (TREE_CODE (impent->imp_context) == CATEGORY_IMPLEMENTATION_TYPE)
	{
	  /* Set an invisible arg to synth_id_with_class_suffix.  */
	  objc_implementation_context = impent->imp_context;
	  /* extern struct objc_category _OBJC_CATEGORY_<name>; */
	  impent->class_decl = build_metadata_decl ("_OBJC_CATEGORY",
						    objc_category_template);
	}
    }
  objc_implementation_context = sav;
}

/* Create the declaration of _OBJC_SYMBOLS, with type `struct _objc_symtab'
   and initialized appropriately.  */

static void
generate_objc_symtab_decl (void)
{
  /* forward declare categories */
  if (cat_count)
    forward_declare_categories ();

  build_objc_symtab_template ();
  UOBJC_SYMBOLS_decl = start_var_decl (objc_symtab_template, "_OBJC_SYMBOLS");
  finish_var_decl (UOBJC_SYMBOLS_decl,
		   init_objc_symtab (TREE_TYPE (UOBJC_SYMBOLS_decl)));
}

static tree
init_module_descriptor (tree type)
{
  tree initlist, expr;

  /* version = { 1, ... } */

  expr = build_int_cst (long_integer_type_node, OBJC_VERSION);
  initlist = build_tree_list (NULL_TREE, expr);

  /* size = { ..., sizeof (struct _objc_module), ... } */

  expr = convert (long_integer_type_node,
		  size_in_bytes (objc_module_template));
  initlist = tree_cons (NULL_TREE, expr, initlist);

  /* name = { ..., "foo.m", ... } */

  expr = add_objc_string (get_identifier (input_filename), class_names);
  initlist = tree_cons (NULL_TREE, expr, initlist);

  /* symtab = { ..., _OBJC_SYMBOLS, ... } */

  if (UOBJC_SYMBOLS_decl)
    expr = build_unary_op (ADDR_EXPR, UOBJC_SYMBOLS_dec