C++ TREE_NOTHROW函数代码示例

static tree
do_end_catch (tree type)
{
  tree fn, cleanup;

  fn = get_identifier ("__cxa_end_catch");
  if (!get_global_value_if_present (fn, &fn))
    {
      /* Declare void __cxa_end_catch ().  */
      fn = push_void_library_fn (fn, void_list_node);
      /* This can throw if the destructor for the exception throws.  */
      TREE_NOTHROW (fn) = 0;

      /* Create its transactional-memory equivalent.  */
      if (flag_tm)
	{
	  tree fn2 = get_identifier ("_ITM_cxa_end_catch");
	  if (!get_global_value_if_present (fn2, &fn2))
	    {
	      fn2 = push_void_library_fn (fn2, void_list_node);
	      TREE_NOTHROW (fn2) = 0;
	    }
	  apply_tm_attr (fn2, get_identifier ("transaction_pure"));
	  record_tm_replacement (fn, fn2);
	}
    }

  cleanup = cp_build_function_call_vec (fn, NULL, tf_warning_or_error);
  TREE_NOTHROW (cleanup) = dtor_nothrow (type);

  return cleanup;
}

static inline void
unpack_ts_base_value_fields (struct bitpack_d *bp, tree expr)
{
  /* Note that the code for EXPR has already been unpacked to create EXPR in
     streamer_alloc_tree.  */
  if (!TYPE_P (expr))
    {
      TREE_SIDE_EFFECTS (expr) = (unsigned) bp_unpack_value (bp, 1);
      TREE_CONSTANT (expr) = (unsigned) bp_unpack_value (bp, 1);
      TREE_READONLY (expr) = (unsigned) bp_unpack_value (bp, 1);

      /* TREE_PUBLIC is used on types to indicate that the type
	 has a TYPE_CACHED_VALUES vector.  This is not streamed out,
	 so we skip it here.  */
      TREE_PUBLIC (expr) = (unsigned) bp_unpack_value (bp, 1);
    }
  else
    bp_unpack_value (bp, 4);
  TREE_ADDRESSABLE (expr) = (unsigned) bp_unpack_value (bp, 1);
  TREE_THIS_VOLATILE (expr) = (unsigned) bp_unpack_value (bp, 1);
  if (DECL_P (expr))
    DECL_UNSIGNED (expr) = (unsigned) bp_unpack_value (bp, 1);
  else if (TYPE_P (expr))
    TYPE_UNSIGNED (expr) = (unsigned) bp_unpack_value (bp, 1);
  else
    bp_unpack_value (bp, 1);
  TREE_ASM_WRITTEN (expr) = (unsigned) bp_unpack_value (bp, 1);
  if (TYPE_P (expr))
    TYPE_ARTIFICIAL (expr) = (unsigned) bp_unpack_value (bp, 1);
  else
    TREE_NO_WARNING (expr) = (unsigned) bp_unpack_value (bp, 1);
  TREE_NOTHROW (expr) = (unsigned) bp_unpack_value (bp, 1);
  TREE_STATIC (expr) = (unsigned) bp_unpack_value (bp, 1);
  if (TREE_CODE (expr) != TREE_BINFO)
    TREE_PRIVATE (expr) = (unsigned) bp_unpack_value (bp, 1);
  else
    bp_unpack_value (bp, 1);
  TREE_PROTECTED (expr) = (unsigned) bp_unpack_value (bp, 1);
  TREE_DEPRECATED (expr) = (unsigned) bp_unpack_value (bp, 1);
  if (TYPE_P (expr))
    {
      if (AGGREGATE_TYPE_P (expr))
	TYPE_REVERSE_STORAGE_ORDER (expr) = (unsigned) bp_unpack_value (bp, 1);
      else
	TYPE_SATURATING (expr) = (unsigned) bp_unpack_value (bp, 1);
      TYPE_ADDR_SPACE (expr) = (unsigned) bp_unpack_value (bp, 8);
    }
  else if (TREE_CODE (expr) == BIT_FIELD_REF || TREE_CODE (expr) == MEM_REF)
    {
      REF_REVERSE_STORAGE_ORDER (expr) = (unsigned) bp_unpack_value (bp, 1);
      bp_unpack_value (bp, 8);
    }
  else if (TREE_CODE (expr) == SSA_NAME)
    {
      SSA_NAME_IS_DEFAULT_DEF (expr) = (unsigned) bp_unpack_value (bp, 1);
      bp_unpack_value (bp, 8);
    }
  else
    bp_unpack_value (bp, 9);
}

void
init_exception_processing (void)
{
  tree tmp;

  /* void std::terminate (); */
  push_namespace (std_identifier);
  tmp = build_function_type (void_type_node, void_list_node);
  terminate_node = build_cp_library_fn_ptr ("terminate", tmp);
  TREE_THIS_VOLATILE (terminate_node) = 1;
  TREE_NOTHROW (terminate_node) = 1;
  pop_namespace ();

  /* void __cxa_call_unexpected(void *); */
  tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
  tmp = build_function_type (void_type_node, tmp);
  call_unexpected_node
    = push_throw_library_fn (get_identifier ("__cxa_call_unexpected"), tmp);

  eh_personality_libfunc = init_one_libfunc (USING_SJLJ_EXCEPTIONS
					     ? "__gxx_personality_sj0"
					     : "__gxx_personality_v0");

  lang_eh_runtime_type = build_eh_type_type;
  lang_protect_cleanup_actions = &cp_protect_cleanup_actions;
}

static tree
do_end_catch (tree type)
{
  tree fn, cleanup;

  fn = get_identifier ("__cxa_end_catch");
  if (!get_global_value_if_present (fn, &fn))
    {
      /* Declare void __cxa_end_catch ().  */
      fn = push_void_library_fn (fn, void_list_node);
      /* This can throw if the destructor for the exception throws.  */
      TREE_NOTHROW (fn) = 0;
    }

  cleanup = build_function_call (fn, NULL_TREE);
  TREE_NOTHROW (cleanup) = dtor_nothrow (type);

  return cleanup;
}

static void
maybe_noexcept_warning (tree fn)
{
  if (TREE_NOTHROW (fn))
    {
      warning (OPT_Wnoexcept, "noexcept-expression evaluates to %<false%> "
	       "because of a call to %qD", fn);
      warning (OPT_Wnoexcept, "but %q+D does not throw; perhaps "
	       "it should be declared %<noexcept%>", fn);
    }
}

static int
dtor_nothrow (tree type)
{
  if (type == NULL_TREE)
    return 0;

  if (! TYPE_HAS_DESTRUCTOR (type))
    return 1;

  return TREE_NOTHROW (CLASSTYPE_DESTRUCTORS (type));
}

static tree
handle_nothrow_attribute (tree *node, tree ARG_UNUSED (name),
			  tree ARG_UNUSED (args), int ARG_UNUSED (flags),
			  bool * ARG_UNUSED (no_add_attrs))
{
  if (TREE_CODE (*node) == FUNCTION_DECL)
    TREE_NOTHROW (*node) = 1;
  else
    gcc_unreachable ();

  return NULL_TREE;
}

static int
dtor_nothrow (tree type)
{
  if (type == NULL_TREE)
    return 0;

  if (!CLASS_TYPE_P (type))
    return 1;

  if (CLASSTYPE_LAZY_DESTRUCTOR (type))
    lazily_declare_fn (sfk_destructor, type);

  return TREE_NOTHROW (CLASSTYPE_DESTRUCTORS (type));
}

static int
dtor_nothrow (tree type)
{
  if (type == NULL_TREE || type == error_mark_node)
    return 0;

  if (TYPE_HAS_TRIVIAL_DESTRUCTOR (type))
    return 1;

  if (CLASSTYPE_LAZY_DESTRUCTOR (type))
    lazily_declare_fn (sfk_destructor, type);

  return TREE_NOTHROW (CLASSTYPE_DESTRUCTOR (type));
}

static void
pack_ts_base_value_fields (struct bitpack_d *bp, tree expr)
{
  bp_pack_value (bp, TREE_CODE (expr), 16);
  if (!TYPE_P (expr))
    {
      bp_pack_value (bp, TREE_SIDE_EFFECTS (expr), 1);
      bp_pack_value (bp, TREE_CONSTANT (expr), 1);
      bp_pack_value (bp, TREE_READONLY (expr), 1);

      /* TREE_PUBLIC is used on types to indicate that the type
	 has a TYPE_CACHED_VALUES vector.  This is not streamed out,
	 so we skip it here.  */
      bp_pack_value (bp, TREE_PUBLIC (expr), 1);
    }
  else
    bp_pack_value (bp, 0, 4);
  bp_pack_value (bp, TREE_ADDRESSABLE (expr), 1);
  bp_pack_value (bp, TREE_THIS_VOLATILE (expr), 1);
  if (DECL_P (expr))
    bp_pack_value (bp, DECL_UNSIGNED (expr), 1);
  else if (TYPE_P (expr))
    bp_pack_value (bp, TYPE_UNSIGNED (expr), 1);
  else
    bp_pack_value (bp, 0, 1);
  /* We write debug info two times, do not confuse the second one.
     The only relevant TREE_ASM_WRITTEN use is on SSA names.  */
  bp_pack_value (bp, (TREE_CODE (expr) != SSA_NAME
		      ? 0 : TREE_ASM_WRITTEN (expr)), 1);
  if (TYPE_P (expr))
    bp_pack_value (bp, TYPE_ARTIFICIAL (expr), 1);
  else
    bp_pack_value (bp, TREE_NO_WARNING (expr), 1);
  bp_pack_value (bp, TREE_NOTHROW (expr), 1);
  bp_pack_value (bp, TREE_STATIC (expr), 1);
  if (TREE_CODE (expr) != TREE_BINFO)
    bp_pack_value (bp, TREE_PRIVATE (expr), 1);
  bp_pack_value (bp, TREE_PROTECTED (expr), 1);
  bp_pack_value (bp, TREE_DEPRECATED (expr), 1);
  if (TYPE_P (expr))
    {
      bp_pack_value (bp, TYPE_SATURATING (expr), 1);
      bp_pack_value (bp, TYPE_ADDR_SPACE (expr), 8);
    }
  else if (TREE_CODE (expr) == SSA_NAME)
    bp_pack_value (bp, SSA_NAME_IS_DEFAULT_DEF (expr), 1);
  else
    bp_pack_value (bp, 0, 1);
}

static tree
do_end_catch (tree type)
{
  tree fn, cleanup;

  /* APPLE LOCAL begin radar 2848255 */
  if (c_dialect_objc () && objc2_valid_objc_catch_type (type))
    fn = get_identifier ("objc_end_catch");
  else
    fn = get_identifier ("__cxa_end_catch");
  /* APPLE LOCAL end radar 2848255 */
  if (!get_global_value_if_present (fn, &fn))
    {
      /* Declare void __cxa_end_catch ().  */
      fn = push_void_library_fn (fn, void_list_node);
      /* This can throw if the destructor for the exception throws.  */
      TREE_NOTHROW (fn) = 0;
    }

  cleanup = build_function_call (fn, NULL_TREE);
  TREE_NOTHROW (cleanup) = dtor_nothrow (type);

  return cleanup;
}

static tree
do_end_catch (tree type)
{
  if (!end_catch_fn)
    /* Declare void __cxa_end_catch ().
       This can throw if the destructor for the exception throws.  */
    end_catch_fn
      = declare_library_fn ("__cxa_end_catch", void_type_node,
			    NULL_TREE, 0, ECF_TM_PURE);

  tree cleanup = cp_build_function_call_vec (end_catch_fn,
					     NULL, tf_warning_or_error);
  TREE_NOTHROW (cleanup) = dtor_nothrow (type);

  return cleanup;
}

static tree
declare_cilk_for_builtin (const char *name, tree type,
			  enum built_in_function code)
{
  tree cb, ft, fn;

  cb = build_function_type_list (void_type_node,
				 ptr_type_node, type, type,
				 NULL_TREE);
  cb = build_pointer_type (cb);
  ft = build_function_type_list (void_type_node,
				 cb, ptr_type_node, type,
				 integer_type_node, NULL_TREE);
  fn = install_builtin (name, ft, code, false);
  TREE_NOTHROW (fn) = 0;

  return fn;
}

void
init_exception_processing (void)
{
  tree tmp;

  /* void std::terminate (); */
  push_namespace (std_identifier);
  tmp = build_function_type_list (void_type_node, NULL_TREE);
  terminate_node = build_cp_library_fn_ptr ("terminate", tmp);
  TREE_THIS_VOLATILE (terminate_node) = 1;
  TREE_NOTHROW (terminate_node) = 1;
  pop_namespace ();

  /* void __cxa_call_unexpected(void *); */
  tmp = build_function_type_list (void_type_node, ptr_type_node, NULL_TREE);
  call_unexpected_node
    = push_throw_library_fn (get_identifier ("__cxa_call_unexpected"), tmp);
}

static tree
check_noexcept_r (tree *tp, int * /*walk_subtrees*/, void * /*data*/)
{
  tree t = *tp;
  enum tree_code code = TREE_CODE (t);
  if ((code == CALL_EXPR && CALL_EXPR_FN (t))
      || code == AGGR_INIT_EXPR)
    {
      /* We can only use the exception specification of the called function
	 for determining the value of a noexcept expression; we can't use
	 TREE_NOTHROW, as it might have a different value in another
	 translation unit, creating ODR problems.

         We could use TREE_NOTHROW (t) for !TREE_PUBLIC fns, though... */
      tree fn = (code == AGGR_INIT_EXPR
		 ? AGGR_INIT_EXPR_FN (t) : CALL_EXPR_FN (t));
      tree type = TREE_TYPE (fn);
      gcc_assert (POINTER_TYPE_P (type));
      type = TREE_TYPE (type);

      STRIP_NOPS (fn);
      if (TREE_CODE (fn) == ADDR_EXPR)
	fn = TREE_OPERAND (fn, 0);
      if (TREE_CODE (fn) == FUNCTION_DECL)
	{
	  /* We do use TREE_NOTHROW for ABI internals like __dynamic_cast,
	     and for C library functions known not to throw.  */
	  if (DECL_EXTERN_C_P (fn)
	      && (DECL_ARTIFICIAL (fn)
		  || nothrow_libfn_p (fn)))
	    return TREE_NOTHROW (fn) ? NULL_TREE : fn;
	  /* A call to a constexpr function is noexcept if the call
	     is a constant expression.  */
	  if (DECL_DECLARED_CONSTEXPR_P (fn)
	      && is_sub_constant_expr (t))
	    return NULL_TREE;
	}
      if (!TYPE_NOTHROW_P (type))
	return fn;
    }

  return NULL_TREE;
}