1 /* Handle exceptional things in C++.
2 Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
3 2000, 2001 Free Software Foundation, Inc.
4 Contributed by Michael Tiemann <tiemann@cygnus.com>
5 Rewritten by Mike Stump <mrs@cygnus.com>, based upon an
6 initial re-implementation courtesy Tad Hunt.
8 This file is part of GNU CC.
10 GNU CC is free software; you can redistribute it and/or modify
11 it under the terms of the GNU General Public License as published by
12 the Free Software Foundation; either version 2, or (at your option)
15 GNU CC is distributed in the hope that it will be useful,
16 but WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 GNU General Public License for more details.
20 You should have received a copy of the GNU General Public License
21 along with GNU CC; see the file COPYING. If not, write to
22 the Free Software Foundation, 59 Temple Place - Suite 330,
23 Boston, MA 02111-1307, USA. */
39 static void push_eh_cleanup PARAMS ((tree));
40 static tree prepare_eh_type PARAMS ((tree));
41 static tree build_eh_type_type PARAMS ((tree));
42 static tree do_begin_catch PARAMS ((void));
43 static int dtor_nothrow PARAMS ((tree));
44 static tree do_end_catch PARAMS ((tree));
45 static void push_eh_cleanup PARAMS ((tree));
46 static bool decl_is_java_type PARAMS ((tree decl, int err));
47 static void initialize_handler_parm PARAMS ((tree, tree));
48 static tree do_allocate_exception PARAMS ((tree));
49 static int complete_ptr_ref_or_void_ptr_p PARAMS ((tree, tree));
50 static bool is_admissible_throw_operand PARAMS ((tree));
51 static int can_convert_eh PARAMS ((tree, tree));
52 static void check_handlers_1 PARAMS ((tree, tree));
53 static tree cp_protect_cleanup_actions PARAMS ((void));
58 /* Sets up all the global eh stuff that needs to be initialized at the
59 start of compilation. */
62 init_exception_processing ()
66 /* void std::terminate (); */
67 push_namespace (std_identifier);
68 tmp = build_function_type (void_type_node, void_list_node);
69 terminate_node = build_cp_library_fn_ptr ("terminate", tmp);
70 TREE_THIS_VOLATILE (terminate_node) = 1;
71 TREE_NOTHROW (terminate_node) = 1;
74 /* void __cxa_call_unexpected(void *); */
75 tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
76 tmp = build_function_type (void_type_node, tmp);
78 = push_throw_library_fn (get_identifier ("__cxa_call_unexpected"), tmp);
80 eh_personality_libfunc = init_one_libfunc (USING_SJLJ_EXCEPTIONS
81 ? "__gxx_personality_sj0"
82 : "__gxx_personality_v0");
84 lang_eh_runtime_type = build_eh_type_type;
85 lang_protect_cleanup_actions = &cp_protect_cleanup_actions;
88 /* Returns an expression to be executed if an unhandled exception is
89 propagated out of a cleanup region. */
92 cp_protect_cleanup_actions ()
96 When the destruction of an object during stack unwinding exits
97 using an exception ... void terminate(); is called. */
98 return build_call (terminate_node, NULL_TREE);
102 prepare_eh_type (type)
105 if (type == NULL_TREE)
107 if (type == error_mark_node)
108 return error_mark_node;
110 /* peel back references, so they match. */
111 if (TREE_CODE (type) == REFERENCE_TYPE)
112 type = TREE_TYPE (type);
114 /* Peel off cv qualifiers. */
115 type = TYPE_MAIN_VARIANT (type);
120 /* Build the address of a typeinfo decl for use in the runtime
121 matching field of the exception model. */
124 build_eh_type_type (type)
129 if (type == NULL_TREE || type == error_mark_node)
132 if (decl_is_java_type (type, 0))
133 exp = build_java_class_ref (TREE_TYPE (type));
135 exp = get_tinfo_decl (type);
138 exp = build1 (ADDR_EXPR, ptr_type_node, exp);
146 return build (EXC_PTR_EXPR, ptr_type_node);
149 /* Build up a call to __cxa_begin_catch, to tell the runtime that the
150 exception has been handled. */
157 fn = get_identifier ("__cxa_begin_catch");
158 if (IDENTIFIER_GLOBAL_VALUE (fn))
159 fn = IDENTIFIER_GLOBAL_VALUE (fn);
162 /* Declare void* __cxa_begin_catch (void *). */
163 tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
164 fn = push_library_fn (fn, build_function_type (ptr_type_node, tmp));
167 return build_function_call (fn, tree_cons (NULL_TREE, build_exc_ptr (),
171 /* Returns nonzero if cleaning up an exception of type TYPE (which can be
172 NULL_TREE for a ... handler) will not throw an exception. */
180 if (type == NULL_TREE)
183 if (! TYPE_HAS_DESTRUCTOR (type))
186 fn = lookup_member (type, dtor_identifier, 0, 0);
187 fn = TREE_VALUE (fn);
188 return TREE_NOTHROW (fn);
191 /* Build up a call to __cxa_end_catch, to destroy the exception object
192 for the current catch block if no others are currently using it. */
200 fn = get_identifier ("__cxa_end_catch");
201 if (IDENTIFIER_GLOBAL_VALUE (fn))
202 fn = IDENTIFIER_GLOBAL_VALUE (fn);
205 /* Declare void __cxa_end_catch (). */
206 fn = push_void_library_fn (fn, void_list_node);
207 /* This can throw if the destructor for the exception throws. */
208 TREE_NOTHROW (fn) = 0;
211 cleanup = build_function_call (fn, NULL_TREE);
212 TREE_NOTHROW (cleanup) = dtor_nothrow (type);
217 /* This routine creates the cleanup for the current exception. */
220 push_eh_cleanup (type)
223 finish_decl_cleanup (NULL_TREE, do_end_catch (type));
226 /* Return nonzero value if DECL is a Java type suitable for catch or
230 decl_is_java_type (decl, err)
234 bool r = (TREE_CODE (decl) == POINTER_TYPE
235 && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
236 && TYPE_FOR_JAVA (TREE_TYPE (decl)));
240 if (TREE_CODE (decl) == REFERENCE_TYPE
241 && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
242 && TYPE_FOR_JAVA (TREE_TYPE (decl)))
244 /* Can't throw a reference. */
245 error ("type `%T' is disallowed in Java `throw' or `catch'",
252 = IDENTIFIER_GLOBAL_VALUE (get_identifier ("jthrowable"));
254 if (jthrow_node == NULL_TREE)
256 ("call to Java `catch' or `throw' with `jthrowable' undefined");
258 jthrow_node = TREE_TYPE (TREE_TYPE (jthrow_node));
260 if (! DERIVED_FROM_P (jthrow_node, TREE_TYPE (decl)))
262 /* Thrown object must be a Throwable. */
263 error ("type `%T' is not derived from `java::lang::Throwable'",
272 /* Select the personality routine to be used for exception handling,
273 or issue an error if we need two different ones in the same
275 ??? At present eh_personality_libfunc is set to
276 __gxx_personality_(sj|v)0 in init_exception_processing - should it
277 be done here instead? */
279 choose_personality_routine (lang)
295 if (lang != lang_cplusplus)
300 if (lang != lang_java)
305 ; /* proceed to language selection */
316 eh_personality_libfunc = init_one_libfunc (USING_SJLJ_EXCEPTIONS
317 ? "__gcj_personality_sj0"
318 : "__gcj_personality_v0");
327 error ("mixing C++ and Java catches in a single translation unit");
331 /* Initialize the catch parameter DECL. */
334 initialize_handler_parm (decl, exp)
341 /* Make sure we mark the catch param as used, otherwise we'll get a
342 warning about an unused ((anonymous)). */
343 TREE_USED (decl) = 1;
345 /* Figure out the type that the initializer is. Pointers are returned
346 adjusted by value from __cxa_begin_catch. Others are returned by
348 init_type = TREE_TYPE (decl);
349 if (! TYPE_PTR_P (init_type)
350 && TREE_CODE (init_type) != REFERENCE_TYPE)
351 init_type = build_reference_type (init_type);
353 choose_personality_routine (decl_is_java_type (init_type, 0)
354 ? lang_java : lang_cplusplus);
356 /* Since pointers are passed by value, initialize a reference to
357 pointer catch parm with the address of the temporary. */
358 if (TREE_CODE (init_type) == REFERENCE_TYPE
359 && TYPE_PTR_P (TREE_TYPE (init_type)))
360 exp = build_unary_op (ADDR_EXPR, exp, 1);
362 exp = ocp_convert (init_type, exp, CONV_IMPLICIT|CONV_FORCE_TEMP, 0);
364 init = convert_from_reference (exp);
366 /* If the constructor for the catch parm exits via an exception, we
367 must call terminate. See eh23.C. */
368 if (TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl)))
370 /* Generate the copy constructor call directly so we can wrap it.
371 See also expand_default_init. */
372 init = ocp_convert (TREE_TYPE (decl), init,
373 CONV_IMPLICIT|CONV_FORCE_TEMP, 0);
374 init = build1 (MUST_NOT_THROW_EXPR, TREE_TYPE (init), init);
377 /* Let `cp_finish_decl' know that this initializer is ok. */
378 DECL_INITIAL (decl) = error_mark_node;
379 decl = pushdecl (decl);
382 cp_finish_decl (decl, init, NULL_TREE,
383 LOOKUP_ONLYCONVERTING|DIRECT_BIND);
386 /* Call this to start a catch block. DECL is the catch parameter. */
389 expand_start_catch_block (decl)
392 tree exp = NULL_TREE;
399 /* Make sure this declaration is reasonable. */
400 if (decl && !complete_ptr_ref_or_void_ptr_p (TREE_TYPE (decl), NULL_TREE))
404 type = prepare_eh_type (TREE_TYPE (decl));
413 if (decl_is_java_type (type, 1))
415 /* Java only passes object via pointer and doesn't require
416 adjusting. The java object is immediately before the
417 generic exception header. */
418 init = build_exc_ptr ();
419 init = build1 (NOP_EXPR, build_pointer_type (type), init);
420 init = build (MINUS_EXPR, TREE_TYPE (init), init,
421 TYPE_SIZE_UNIT (TREE_TYPE (init)));
422 init = build_indirect_ref (init, NULL);
427 /* C++ requires that we call __cxa_begin_catch to get the
428 pointer to the actual object. */
429 init = do_begin_catch ();
432 exp = create_temporary_var (ptr_type_node);
433 DECL_REGISTER (exp) = 1;
434 cp_finish_decl (exp, init, NULL_TREE, LOOKUP_ONLYCONVERTING);
435 finish_expr_stmt (build_modify_expr (exp, INIT_EXPR, init));
438 finish_expr_stmt (do_begin_catch ());
440 /* C++ requires that we call __cxa_end_catch at the end of
441 processing the exception. */
443 push_eh_cleanup (type);
446 initialize_handler_parm (decl, exp);
452 /* Call this to end a catch block. Its responsible for emitting the
453 code to handle jumping back to the correct place, and for emitting
454 the label to jump to if this catch block didn't match. */
457 expand_end_catch_block ()
462 /* The exception being handled is rethrown if control reaches the end of
463 a handler of the function-try-block of a constructor or destructor. */
464 if (in_function_try_handler
465 && (DECL_CONSTRUCTOR_P (current_function_decl)
466 || DECL_DESTRUCTOR_P (current_function_decl)))
467 finish_expr_stmt (build_throw (NULL_TREE));
471 begin_eh_spec_block ()
473 tree r = build_stmt (EH_SPEC_BLOCK, NULL_TREE, NULL_TREE);
479 finish_eh_spec_block (raw_raises, eh_spec_block)
485 RECHAIN_STMTS (eh_spec_block, EH_SPEC_STMTS (eh_spec_block));
487 /* Strip cv quals, etc, from the specification types. */
488 for (raises = NULL_TREE;
489 raw_raises && TREE_VALUE (raw_raises);
490 raw_raises = TREE_CHAIN (raw_raises))
491 raises = tree_cons (NULL_TREE, prepare_eh_type (TREE_VALUE (raw_raises)),
494 EH_SPEC_RAISES (eh_spec_block) = raises;
497 /* Return a pointer to a buffer for an exception object of type TYPE. */
500 do_allocate_exception (type)
505 fn = get_identifier ("__cxa_allocate_exception");
506 if (IDENTIFIER_GLOBAL_VALUE (fn))
507 fn = IDENTIFIER_GLOBAL_VALUE (fn);
510 /* Declare void *__cxa_allocate_exception(size_t). */
511 tree tmp = tree_cons (NULL_TREE, c_size_type_node, void_list_node);
512 fn = push_library_fn (fn, build_function_type (ptr_type_node, tmp));
515 return build_function_call (fn, tree_cons (NULL_TREE, size_in_bytes (type),
520 /* Call __cxa_free_exception from a cleanup. This is never invoked
524 do_free_exception (ptr)
529 fn = get_identifier ("__cxa_free_exception");
530 if (IDENTIFIER_GLOBAL_VALUE (fn))
531 fn = IDENTIFIER_GLOBAL_VALUE (fn);
534 /* Declare void __cxa_free_exception (void *). */
535 fn = push_void_library_fn (fn, tree_cons (NULL_TREE, ptr_type_node,
539 return build_function_call (fn, tree_cons (NULL_TREE, ptr, NULL_TREE));
543 /* Build a throw expression. */
551 if (exp == error_mark_node)
554 if (processing_template_decl)
555 return build_min (THROW_EXPR, void_type_node, exp);
557 if (exp == null_node)
558 warning ("throwing NULL, which has integral, not pointer type");
560 if (exp != NULL_TREE)
562 if (!is_admissible_throw_operand (exp))
563 return error_mark_node;
567 return error_mark_node;
569 if (exp && decl_is_java_type (TREE_TYPE (exp), 1))
571 tree fn = get_identifier ("_Jv_Throw");
572 if (IDENTIFIER_GLOBAL_VALUE (fn))
573 fn = IDENTIFIER_GLOBAL_VALUE (fn);
576 /* Declare void _Jv_Throw (void *). */
577 tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
578 tmp = build_function_type (ptr_type_node, tmp);
579 fn = push_throw_library_fn (fn, tmp);
582 exp = build_function_call (fn, tree_cons (NULL_TREE, exp, NULL_TREE));
593 fn = get_identifier ("__cxa_throw");
594 if (IDENTIFIER_GLOBAL_VALUE (fn))
595 fn = IDENTIFIER_GLOBAL_VALUE (fn);
598 /* The CLEANUP_TYPE is the internal type of a destructor. */
599 if (cleanup_type == NULL_TREE)
601 tmp = void_list_node;
602 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
603 tmp = build_function_type (void_type_node, tmp);
604 cleanup_type = build_pointer_type (tmp);
607 /* Declare void __cxa_throw (void*, void*, void (*)(void*)). */
608 /* ??? Second argument is supposed to be "std::type_info*". */
609 tmp = void_list_node;
610 tmp = tree_cons (NULL_TREE, cleanup_type, tmp);
611 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
612 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
613 tmp = build_function_type (void_type_node, tmp);
614 fn = push_throw_library_fn (fn, tmp);
617 begin_init_stmts (&stmt_expr, &compound_stmt);
619 /* throw expression */
620 /* First, decay it. */
621 exp = decay_conversion (exp);
623 /* OK, this is kind of wacky. The standard says that we call
624 terminate when the exception handling mechanism, after
625 completing evaluation of the expression to be thrown but
626 before the exception is caught (_except.throw_), calls a
627 user function that exits via an uncaught exception.
629 So we have to protect the actual initialization of the
630 exception object with terminate(), but evaluate the
631 expression first. Since there could be temps in the
632 expression, we need to handle that, too. We also expand
633 the call to __cxa_allocate_exception first (which doesn't
634 matter, since it can't throw). */
636 my_friendly_assert (stmts_are_full_exprs_p () == 1, 19990926);
638 /* Store the throw expression into a temp. This can be less
639 efficient than storing it into the allocated space directly, but
640 if we allocated the space first we would have to deal with
641 cleaning it up if evaluating this expression throws. */
642 if (TREE_SIDE_EFFECTS (exp))
644 tmp = create_temporary_var (TREE_TYPE (exp));
645 DECL_INITIAL (tmp) = exp;
646 cp_finish_decl (tmp, exp, NULL_TREE, LOOKUP_ONLYCONVERTING);
650 /* Allocate the space for the exception. */
651 ptr = create_temporary_var (ptr_type_node);
652 DECL_REGISTER (ptr) = 1;
653 cp_finish_decl (ptr, NULL_TREE, NULL_TREE, LOOKUP_ONLYCONVERTING);
654 tmp = do_allocate_exception (TREE_TYPE (exp));
655 tmp = build_modify_expr (ptr, INIT_EXPR, tmp);
656 finish_expr_stmt (tmp);
658 object = build1 (NOP_EXPR, build_pointer_type (TREE_TYPE (exp)), ptr);
659 object = build_indirect_ref (object, NULL);
661 exp = build_modify_expr (object, INIT_EXPR, exp);
662 if (exp == error_mark_node)
663 error (" in thrown expression");
665 exp = build1 (MUST_NOT_THROW_EXPR, TREE_TYPE (exp), exp);
666 finish_expr_stmt (exp);
668 throw_type = build_eh_type_type (prepare_eh_type (TREE_TYPE (object)));
670 if (TYPE_HAS_DESTRUCTOR (TREE_TYPE (object)))
672 cleanup = lookup_fnfields (TYPE_BINFO (TREE_TYPE (object)),
673 complete_dtor_identifier, 0);
674 cleanup = TREE_VALUE (cleanup);
676 mark_addressable (cleanup);
677 /* Pretend it's a normal function. */
678 cleanup = build1 (ADDR_EXPR, cleanup_type, cleanup);
682 cleanup = build_int_2 (0, 0);
683 TREE_TYPE (cleanup) = cleanup_type;
686 tmp = tree_cons (NULL_TREE, cleanup, NULL_TREE);
687 tmp = tree_cons (NULL_TREE, throw_type, tmp);
688 tmp = tree_cons (NULL_TREE, ptr, tmp);
689 tmp = build_function_call (fn, tmp);
691 /* ??? Indicate that this function call throws throw_type. */
693 finish_expr_stmt (tmp);
695 exp = finish_init_stmts (stmt_expr, compound_stmt);
699 /* Rethrow current exception. */
701 tree fn = get_identifier ("__cxa_rethrow");
702 if (IDENTIFIER_GLOBAL_VALUE (fn))
703 fn = IDENTIFIER_GLOBAL_VALUE (fn);
706 /* Declare void __cxa_rethrow (void). */
707 fn = push_throw_library_fn
708 (fn, build_function_type (void_type_node, void_list_node));
711 exp = build_function_call (fn, NULL_TREE);
714 exp = build1 (THROW_EXPR, void_type_node, exp);
719 /* Make sure TYPE is complete, pointer to complete, reference to
720 complete, or pointer to cv void. Issue diagnostic on failure.
721 Return the zero on failure and non-zero on success. FROM can be
722 the expr or decl from whence TYPE came, if available. */
725 complete_ptr_ref_or_void_ptr_p (type, from)
731 /* Check complete. */
732 type = complete_type_or_else (type, from);
736 /* Or a pointer or ref to one, or cv void *. */
737 is_ptr = TREE_CODE (type) == POINTER_TYPE;
738 if (is_ptr || TREE_CODE (type) == REFERENCE_TYPE)
740 tree core = TREE_TYPE (type);
742 if (is_ptr && VOID_TYPE_P (core))
744 else if (!complete_type_or_else (core, from))
750 /* Return truth-value if EXPRESSION is admissible in throw-expression,
751 i.e. if it is not of incomplete type or a pointer/reference to such
752 a type or of an abstract class type. */
755 is_admissible_throw_operand (expr)
758 tree type = TREE_TYPE (expr);
760 /* 15.1/4 [...] The type of the throw-expression shall not be an
761 incomplete type, or a pointer or a reference to an incomplete
762 type, other than void*, const void*, volatile void*, or
763 const volatile void*. Except for these restriction and the
764 restrictions on type matching mentioned in 15.3, the operand
765 of throw is treated exactly as a function argument in a call
766 (5.2.2) or the operand of a return statement. */
767 if (!complete_ptr_ref_or_void_ptr_p (type, expr))
770 /* 10.4/3 An abstract class shall not be used as a parameter type,
771 as a function return type or as type of an explicit
773 else if (CLASS_TYPE_P (type) && CLASSTYPE_PURE_VIRTUALS (type))
775 error ("expression '%E' of abstract class type '%T' cannot be used in throw-expression", expr, type);
782 /* Returns nonzero if FN is a declaration of a standard C library
783 function which is known not to throw.
785 [lib.res.on.exception.handling]: None of the functions from the
786 Standard C library shall report an error by throwing an
787 exception, unless it calls a program-supplied function that
788 throws an exception. */
799 && DECL_EXTERNAL (fn)
800 && DECL_NAMESPACE_SCOPE_P (fn)
801 && DECL_EXTERN_C_P (fn))
804 /* Can't be a C library function. */
807 id = DECL_ASSEMBLER_NAME (fn);
808 return !!libc_name_p (IDENTIFIER_POINTER (id), IDENTIFIER_LENGTH (id));
811 /* Returns nonzero if an exception of type FROM will be caught by a
812 handler for type TO, as per [except.handle]. */
815 can_convert_eh (to, from)
818 if (TREE_CODE (to) == REFERENCE_TYPE)
820 if (TREE_CODE (from) == REFERENCE_TYPE)
821 from = TREE_TYPE (from);
823 if (TREE_CODE (to) == POINTER_TYPE && TREE_CODE (from) == POINTER_TYPE)
826 from = TREE_TYPE (from);
828 if (! at_least_as_qualified_p (to, from))
831 if (TREE_CODE (to) == VOID_TYPE)
834 /* else fall through */
837 if (CLASS_TYPE_P (to) && CLASS_TYPE_P (from)
838 && PUBLICLY_UNIQUELY_DERIVED_P (to, from))
844 /* Check whether any of HANDLERS are shadowed by another handler accepting
845 TYPE. Note that the shadowing may not be complete; even if an exception
846 of type B would be caught by a handler for A, there could be a derived
847 class C for which A is an ambiguous base but B is not, so the handler
848 for B would catch an exception of type C. */
851 check_handlers_1 (master, handlers)
855 tree type = TREE_TYPE (master);
858 for (handler = handlers; handler; handler = TREE_CHAIN (handler))
859 if (TREE_TYPE (handler)
860 && can_convert_eh (type, TREE_TYPE (handler)))
862 lineno = STMT_LINENO (handler);
863 warning ("exception of type `%T' will be caught",
864 TREE_TYPE (handler));
865 lineno = STMT_LINENO (master);
866 warning (" by earlier handler for `%T'", type);
871 /* Given a chain of HANDLERs, make sure that they're OK. */
874 check_handlers (handlers)
878 int save_line = lineno;
879 for (handler = handlers; handler; handler = TREE_CHAIN (handler))
881 if (TREE_CHAIN (handler) == NULL_TREE)
882 /* No more handlers; nothing to shadow. */;
883 else if (TREE_TYPE (handler) == NULL_TREE)
885 lineno = STMT_LINENO (handler);
887 ("`...' handler must be the last handler for its try block");
890 check_handlers_1 (handler, TREE_CHAIN (handler));