1 /* Handle exceptional things in C++.
2 Copyright (C) 1989-2015 Free Software Foundation, Inc.
3 Contributed by Michael Tiemann <tiemann@cygnus.com>
4 Rewritten by Mike Stump <mrs@cygnus.com>, based upon an
5 initial re-implementation courtesy Tad Hunt.
7 This file is part of GCC.
9 GCC is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 3, or (at your option)
14 GCC is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with GCC; see the file COPYING3. If not see
21 <http://www.gnu.org/licenses/>. */
26 #include "coretypes.h"
31 #include "stringpool.h"
32 #include "trans-mem.h"
36 #include "tree-inline.h"
37 #include "tree-iterator.h"
40 static void push_eh_cleanup (tree
);
41 static tree
prepare_eh_type (tree
);
42 static tree
do_begin_catch (void);
43 static int dtor_nothrow (tree
);
44 static tree
do_end_catch (tree
);
45 static bool decl_is_java_type (tree decl
, int err
);
46 static void initialize_handler_parm (tree
, tree
);
47 static tree
do_allocate_exception (tree
);
48 static tree
wrap_cleanups_r (tree
*, int *, void *);
49 static int complete_ptr_ref_or_void_ptr_p (tree
, tree
);
50 static bool is_admissible_throw_operand_or_catch_parameter (tree
, bool);
51 static int can_convert_eh (tree
, tree
);
53 /* Sets up all the global eh stuff that needs to be initialized at the
54 start of compilation. */
57 init_exception_processing (void)
61 /* void std::terminate (); */
62 push_namespace (std_identifier
);
63 tmp
= build_function_type_list (void_type_node
, NULL_TREE
);
64 terminate_node
= build_cp_library_fn_ptr ("terminate", tmp
,
65 ECF_NOTHROW
| ECF_NORETURN
);
66 TREE_THIS_VOLATILE (terminate_node
) = 1;
67 TREE_NOTHROW (terminate_node
) = 1;
70 /* void __cxa_call_unexpected(void *); */
71 tmp
= build_function_type_list (void_type_node
, ptr_type_node
, NULL_TREE
);
73 = push_throw_library_fn (get_identifier ("__cxa_call_unexpected"), tmp
);
76 /* Returns an expression to be executed if an unhandled exception is
77 propagated out of a cleanup region. */
80 cp_protect_cleanup_actions (void)
84 When the destruction of an object during stack unwinding exits
85 using an exception ... void terminate(); is called. */
86 return terminate_node
;
90 prepare_eh_type (tree type
)
92 if (type
== NULL_TREE
)
94 if (type
== error_mark_node
)
95 return error_mark_node
;
97 /* peel back references, so they match. */
98 type
= non_reference (type
);
100 /* Peel off cv qualifiers. */
101 type
= TYPE_MAIN_VARIANT (type
);
103 /* Functions and arrays decay to pointers. */
104 type
= type_decays_to (type
);
109 /* Return the type info for TYPE as used by EH machinery. */
111 eh_type_info (tree type
)
115 if (type
== NULL_TREE
|| type
== error_mark_node
)
118 if (decl_is_java_type (type
, 0))
119 exp
= build_java_class_ref (TREE_TYPE (type
));
121 exp
= get_tinfo_decl (type
);
126 /* Build the address of a typeinfo decl for use in the runtime
127 matching field of the exception model. */
130 build_eh_type_type (tree type
)
132 tree exp
= eh_type_info (type
);
139 return convert (ptr_type_node
, build_address (exp
));
145 return build_call_n (builtin_decl_explicit (BUILT_IN_EH_POINTER
),
146 1, integer_zero_node
);
149 /* Declare a function NAME, returning RETURN_TYPE, taking a single
150 parameter PARM_TYPE, with an empty exception specification.
152 Note that the C++ ABI document does not have a throw-specifier on
153 the routines declared below via this function. The declarations
154 are consistent with the actual implementations in libsupc++. */
157 declare_library_fn (tree name
, tree return_type
, tree parm_type
, int ecf_flags
)
159 return push_library_fn (name
, build_function_type_list (return_type
,
166 /* Build up a call to __cxa_get_exception_ptr so that we can build a
167 copy constructor for the thrown object. */
170 do_get_exception_ptr (void)
174 fn
= get_identifier ("__cxa_get_exception_ptr");
175 if (!get_global_value_if_present (fn
, &fn
))
177 /* Declare void* __cxa_get_exception_ptr (void *) throw(). */
178 fn
= declare_library_fn (fn
, ptr_type_node
, ptr_type_node
,
179 ECF_NOTHROW
| ECF_PURE
| ECF_LEAF
| ECF_TM_PURE
);
182 return cp_build_function_call_nary (fn
, tf_warning_or_error
,
183 build_exc_ptr (), NULL_TREE
);
186 /* Build up a call to __cxa_begin_catch, to tell the runtime that the
187 exception has been handled. */
190 do_begin_catch (void)
194 fn
= get_identifier ("__cxa_begin_catch");
195 if (!get_global_value_if_present (fn
, &fn
))
197 /* Declare void* __cxa_begin_catch (void *) throw(). */
198 fn
= declare_library_fn (fn
, ptr_type_node
, ptr_type_node
, ECF_NOTHROW
);
200 /* Create its transactional-memory equivalent. */
203 tree fn2
= get_identifier ("_ITM_cxa_begin_catch");
204 if (!get_global_value_if_present (fn2
, &fn2
))
205 fn2
= declare_library_fn (fn2
, ptr_type_node
,
206 ptr_type_node
, ECF_NOTHROW
| ECF_TM_PURE
);
207 record_tm_replacement (fn
, fn2
);
211 return cp_build_function_call_nary (fn
, tf_warning_or_error
,
212 build_exc_ptr (), NULL_TREE
);
215 /* Returns nonzero if cleaning up an exception of type TYPE (which can be
216 NULL_TREE for a ... handler) will not throw an exception. */
219 dtor_nothrow (tree type
)
221 if (type
== NULL_TREE
|| type
== error_mark_node
)
224 if (TYPE_HAS_TRIVIAL_DESTRUCTOR (type
))
227 if (CLASSTYPE_LAZY_DESTRUCTOR (type
))
228 lazily_declare_fn (sfk_destructor
, type
);
230 return TREE_NOTHROW (CLASSTYPE_DESTRUCTORS (type
));
233 /* Build up a call to __cxa_end_catch, to destroy the exception object
234 for the current catch block if no others are currently using it. */
237 do_end_catch (tree type
)
241 fn
= get_identifier ("__cxa_end_catch");
242 if (!get_global_value_if_present (fn
, &fn
))
244 /* Declare void __cxa_end_catch ().
245 This can throw if the destructor for the exception throws. */
246 fn
= push_void_library_fn (fn
, void_list_node
, 0);
248 /* Create its transactional-memory equivalent. */
251 tree fn2
= get_identifier ("_ITM_cxa_end_catch");
252 if (!get_global_value_if_present (fn2
, &fn2
))
253 fn2
= push_void_library_fn (fn2
, void_list_node
, ECF_TM_PURE
);
254 record_tm_replacement (fn
, fn2
);
258 cleanup
= cp_build_function_call_vec (fn
, NULL
, tf_warning_or_error
);
259 TREE_NOTHROW (cleanup
) = dtor_nothrow (type
);
264 /* This routine creates the cleanup for the current exception. */
267 push_eh_cleanup (tree type
)
269 finish_decl_cleanup (NULL_TREE
, do_end_catch (type
));
272 /* Return nonzero value if DECL is a Java type suitable for catch or
276 decl_is_java_type (tree decl
, int err
)
278 bool r
= (TYPE_PTR_P (decl
)
279 && TREE_CODE (TREE_TYPE (decl
)) == RECORD_TYPE
280 && TYPE_FOR_JAVA (TREE_TYPE (decl
)));
284 if (TREE_CODE (decl
) == REFERENCE_TYPE
285 && TREE_CODE (TREE_TYPE (decl
)) == RECORD_TYPE
286 && TYPE_FOR_JAVA (TREE_TYPE (decl
)))
288 /* Can't throw a reference. */
289 error ("type %qT is disallowed in Java %<throw%> or %<catch%>",
296 = IDENTIFIER_GLOBAL_VALUE (get_identifier ("jthrowable"));
298 if (jthrow_node
== NULL_TREE
)
301 "call to Java %<catch%> or %<throw%> with %<jthrowable%> undefined");
303 jthrow_node
= TREE_TYPE (TREE_TYPE (jthrow_node
));
305 if (! DERIVED_FROM_P (jthrow_node
, TREE_TYPE (decl
)))
307 /* Thrown object must be a Throwable. */
308 error ("type %qT is not derived from %<java::lang::Throwable%>",
317 /* Select the personality routine to be used for exception handling,
318 or issue an error if we need two different ones in the same
320 ??? At present DECL_FUNCTION_PERSONALITY is set via
321 LANG_HOOKS_EH_PERSONALITY. Should it be done here instead? */
323 choose_personality_routine (enum languages lang
)
338 if (lang
!= lang_cplusplus
)
343 if (lang
!= lang_java
)
348 ; /* Proceed to language selection. */
359 terminate_node
= builtin_decl_explicit (BUILT_IN_ABORT
);
360 pragma_java_exceptions
= true;
369 error ("mixing C++ and Java catches in a single translation unit");
373 /* Wrap EXPR in a MUST_NOT_THROW_EXPR expressing that EXPR must
374 not throw any exceptions if COND is true. A condition of
375 NULL_TREE is treated as 'true'. */
378 build_must_not_throw_expr (tree body
, tree cond
)
380 tree type
= body
? TREE_TYPE (body
) : void_type_node
;
382 if (!flag_exceptions
)
385 if (cond
&& !value_dependent_expression_p (cond
))
387 cond
= cxx_constant_value (cond
);
388 if (integer_zerop (cond
))
390 else if (integer_onep (cond
))
394 return build2 (MUST_NOT_THROW_EXPR
, type
, body
, cond
);
398 /* Initialize the catch parameter DECL. */
401 initialize_handler_parm (tree decl
, tree exp
)
406 /* Make sure we mark the catch param as used, otherwise we'll get a
407 warning about an unused ((anonymous)). */
408 TREE_USED (decl
) = 1;
409 DECL_READ_P (decl
) = 1;
411 /* Figure out the type that the initializer is. Pointers are returned
412 adjusted by value from __cxa_begin_catch. Others are returned by
414 init_type
= TREE_TYPE (decl
);
415 if (!POINTER_TYPE_P (init_type
))
416 init_type
= build_reference_type (init_type
);
418 choose_personality_routine (decl_is_java_type (init_type
, 0)
419 ? lang_java
: lang_cplusplus
);
421 /* Since pointers are passed by value, initialize a reference to
422 pointer catch parm with the address of the temporary. */
423 if (TREE_CODE (init_type
) == REFERENCE_TYPE
424 && TYPE_PTR_P (TREE_TYPE (init_type
)))
425 exp
= cp_build_addr_expr (exp
, tf_warning_or_error
);
427 exp
= ocp_convert (init_type
, exp
, CONV_IMPLICIT
|CONV_FORCE_TEMP
, 0,
428 tf_warning_or_error
);
430 init
= convert_from_reference (exp
);
432 /* If the constructor for the catch parm exits via an exception, we
433 must call terminate. See eh23.C. */
434 if (TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl
)))
436 /* Generate the copy constructor call directly so we can wrap it.
437 See also expand_default_init. */
438 init
= ocp_convert (TREE_TYPE (decl
), init
,
439 CONV_IMPLICIT
|CONV_FORCE_TEMP
, 0,
440 tf_warning_or_error
);
441 /* Force cleanups now to avoid nesting problems with the
442 MUST_NOT_THROW_EXPR. */
443 init
= fold_build_cleanup_point_expr (TREE_TYPE (init
), init
);
444 init
= build_must_not_throw_expr (init
, NULL_TREE
);
447 decl
= pushdecl (decl
);
449 start_decl_1 (decl
, true);
450 cp_finish_decl (decl
, init
, /*init_const_expr_p=*/false, NULL_TREE
,
451 LOOKUP_ONLYCONVERTING
|DIRECT_BIND
);
455 /* Routine to see if exception handling is turned on.
456 DO_WARN is nonzero if we want to inform the user that exception
457 handling is turned off.
459 This is used to ensure that -fexceptions has been specified if the
460 compiler tries to use any exception-specific functions. */
465 if (! flag_exceptions
)
467 static int warned
= 0;
470 error ("exception handling disabled, use -fexceptions to enable");
478 /* Call this to start a catch block. DECL is the catch parameter. */
481 expand_start_catch_block (tree decl
)
491 if (!is_admissible_throw_operand_or_catch_parameter (decl
, false))
492 decl
= error_mark_node
;
494 type
= prepare_eh_type (TREE_TYPE (decl
));
495 mark_used (eh_type_info (type
));
500 if (decl
&& decl_is_java_type (type
, 1))
502 /* Java only passes object via pointer and doesn't require
503 adjusting. The java object is immediately before the
504 generic exception header. */
505 exp
= build_exc_ptr ();
506 exp
= build1 (NOP_EXPR
, build_pointer_type (type
), exp
);
507 exp
= fold_build_pointer_plus (exp
,
508 fold_build1_loc (input_location
,
509 NEGATE_EXPR
, sizetype
,
510 TYPE_SIZE_UNIT (TREE_TYPE (exp
))));
511 exp
= cp_build_indirect_ref (exp
, RO_NULL
, tf_warning_or_error
);
512 initialize_handler_parm (decl
, exp
);
516 /* Call __cxa_end_catch at the end of processing the exception. */
517 push_eh_cleanup (type
);
519 init
= do_begin_catch ();
521 /* If there's no decl at all, then all we need to do is make sure
522 to tell the runtime that we've begun handling the exception. */
523 if (decl
== NULL
|| decl
== error_mark_node
|| init
== error_mark_node
)
524 finish_expr_stmt (init
);
526 /* If the C++ object needs constructing, we need to do that before
527 calling __cxa_begin_catch, so that std::uncaught_exception gets
528 the right value during the copy constructor. */
529 else if (flag_use_cxa_get_exception_ptr
530 && TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl
)))
532 exp
= do_get_exception_ptr ();
533 initialize_handler_parm (decl
, exp
);
534 finish_expr_stmt (init
);
537 /* Otherwise the type uses a bitwise copy, and we don't have to worry
538 about the value of std::uncaught_exception and therefore can do the
539 copy with the return value of __cxa_end_catch instead. */
542 tree init_type
= type
;
544 /* Pointers are passed by values, everything else by reference. */
545 if (!TYPE_PTR_P (type
))
546 init_type
= build_pointer_type (type
);
547 if (init_type
!= TREE_TYPE (init
))
548 init
= build1 (NOP_EXPR
, init_type
, init
);
549 exp
= create_temporary_var (init_type
);
550 DECL_REGISTER (exp
) = 1;
551 cp_finish_decl (exp
, init
, /*init_const_expr=*/false,
552 NULL_TREE
, LOOKUP_ONLYCONVERTING
);
553 initialize_handler_parm (decl
, exp
);
560 /* Call this to end a catch block. Its responsible for emitting the
561 code to handle jumping back to the correct place, and for emitting
562 the label to jump to if this catch block didn't match. */
565 expand_end_catch_block (void)
570 /* The exception being handled is rethrown if control reaches the end of
571 a handler of the function-try-block of a constructor or destructor. */
572 if (in_function_try_handler
573 && (DECL_CONSTRUCTOR_P (current_function_decl
)
574 || DECL_DESTRUCTOR_P (current_function_decl
)))
576 tree rethrow
= build_throw (NULL_TREE
);
577 TREE_NO_WARNING (rethrow
) = true;
578 finish_expr_stmt (rethrow
);
583 begin_eh_spec_block (void)
586 location_t spec_location
= DECL_SOURCE_LOCATION (current_function_decl
);
588 /* A noexcept specification (or throw() with -fnothrow-opt) is a
589 MUST_NOT_THROW_EXPR. */
590 if (TYPE_NOEXCEPT_P (TREE_TYPE (current_function_decl
)))
592 r
= build_stmt (spec_location
, MUST_NOT_THROW_EXPR
,
593 NULL_TREE
, NULL_TREE
);
594 TREE_SIDE_EFFECTS (r
) = 1;
597 r
= build_stmt (spec_location
, EH_SPEC_BLOCK
, NULL_TREE
, NULL_TREE
);
599 TREE_OPERAND (r
, 0) = push_stmt_list ();
604 finish_eh_spec_block (tree raw_raises
, tree eh_spec_block
)
608 TREE_OPERAND (eh_spec_block
, 0)
609 = pop_stmt_list (TREE_OPERAND (eh_spec_block
, 0));
611 if (TREE_CODE (eh_spec_block
) == MUST_NOT_THROW_EXPR
)
614 /* Strip cv quals, etc, from the specification types. */
615 for (raises
= NULL_TREE
;
616 raw_raises
&& TREE_VALUE (raw_raises
);
617 raw_raises
= TREE_CHAIN (raw_raises
))
619 tree type
= prepare_eh_type (TREE_VALUE (raw_raises
));
620 tree tinfo
= eh_type_info (type
);
623 raises
= tree_cons (NULL_TREE
, type
, raises
);
626 EH_SPEC_RAISES (eh_spec_block
) = raises
;
629 /* Return a pointer to a buffer for an exception object of type TYPE. */
632 do_allocate_exception (tree type
)
636 fn
= get_identifier ("__cxa_allocate_exception");
637 if (!get_global_value_if_present (fn
, &fn
))
639 /* Declare void *__cxa_allocate_exception(size_t) throw(). */
640 fn
= declare_library_fn (fn
, ptr_type_node
, size_type_node
,
641 ECF_NOTHROW
| ECF_MALLOC
);
645 tree fn2
= get_identifier ("_ITM_cxa_allocate_exception");
646 if (!get_global_value_if_present (fn2
, &fn2
))
647 fn2
= declare_library_fn (fn2
, ptr_type_node
,
649 ECF_NOTHROW
| ECF_MALLOC
| ECF_TM_PURE
);
650 record_tm_replacement (fn
, fn2
);
654 return cp_build_function_call_nary (fn
, tf_warning_or_error
,
655 size_in_bytes (type
), NULL_TREE
);
658 /* Call __cxa_free_exception from a cleanup. This is never invoked
659 directly, but see the comment for stabilize_throw_expr. */
662 do_free_exception (tree ptr
)
666 fn
= get_identifier ("__cxa_free_exception");
667 if (!get_global_value_if_present (fn
, &fn
))
669 /* Declare void __cxa_free_exception (void *) throw(). */
670 fn
= declare_library_fn (fn
, void_type_node
, ptr_type_node
,
671 ECF_NOTHROW
| ECF_LEAF
);
674 return cp_build_function_call_nary (fn
, tf_warning_or_error
, ptr
, NULL_TREE
);
677 /* Wrap all cleanups for TARGET_EXPRs in MUST_NOT_THROW_EXPR.
678 Called from build_throw via walk_tree_without_duplicates. */
681 wrap_cleanups_r (tree
*tp
, int *walk_subtrees
, void * /*data*/)
686 /* Don't walk into types. */
692 if (TREE_CODE (exp
) != TARGET_EXPR
)
695 cleanup
= TARGET_EXPR_CLEANUP (exp
);
698 cleanup
= build2 (MUST_NOT_THROW_EXPR
, void_type_node
, cleanup
,
700 TARGET_EXPR_CLEANUP (exp
) = cleanup
;
703 /* Keep iterating. */
707 /* Build a throw expression. */
710 build_throw (tree exp
)
714 if (exp
== error_mark_node
)
717 if (processing_template_decl
)
720 current_function_returns_abnormally
= 1;
721 exp
= build_min (THROW_EXPR
, void_type_node
, exp
);
722 SET_EXPR_LOCATION (exp
, input_location
);
726 if (exp
== null_node
)
727 warning (0, "throwing NULL, which has integral, not pointer type");
729 if (exp
!= NULL_TREE
)
731 if (!is_admissible_throw_operand_or_catch_parameter (exp
, true))
732 return error_mark_node
;
736 return error_mark_node
;
738 if (exp
&& decl_is_java_type (TREE_TYPE (exp
), 1))
740 tree fn
= get_identifier ("_Jv_Throw");
741 if (!get_global_value_if_present (fn
, &fn
))
743 /* Declare void _Jv_Throw (void *). */
745 tmp
= build_function_type_list (ptr_type_node
,
746 ptr_type_node
, NULL_TREE
);
747 fn
= push_throw_library_fn (fn
, tmp
);
749 else if (really_overloaded_fn (fn
))
751 error ("%qD should never be overloaded", fn
);
752 return error_mark_node
;
754 fn
= OVL_CURRENT (fn
);
755 exp
= cp_build_function_call_nary (fn
, tf_warning_or_error
,
767 /* The CLEANUP_TYPE is the internal type of a destructor. */
770 tmp
= build_function_type_list (void_type_node
,
771 ptr_type_node
, NULL_TREE
);
772 cleanup_type
= build_pointer_type (tmp
);
775 fn
= get_identifier ("__cxa_throw");
776 if (!get_global_value_if_present (fn
, &fn
))
778 /* Declare void __cxa_throw (void*, void*, void (*)(void*)). */
779 /* ??? Second argument is supposed to be "std::type_info*". */
780 tmp
= build_function_type_list (void_type_node
,
781 ptr_type_node
, ptr_type_node
,
782 cleanup_type
, NULL_TREE
);
783 fn
= push_throw_library_fn (fn
, tmp
);
787 tree fn2
= get_identifier ("_ITM_cxa_throw");
788 if (!get_global_value_if_present (fn2
, &fn2
))
789 fn2
= push_throw_library_fn (fn2
, tmp
);
790 apply_tm_attr (fn2
, get_identifier ("transaction_pure"));
791 record_tm_replacement (fn
, fn2
);
797 A throw-expression initializes a temporary object, the type
798 of which is determined by removing any top-level
799 cv-qualifiers from the static type of the operand of throw
800 and adjusting the type from "array of T" or "function return
801 T" to "pointer to T" or "pointer to function returning T"
803 temp_type
= is_bitfield_expr_with_lowered_type (exp
);
805 temp_type
= cv_unqualified (type_decays_to (TREE_TYPE (exp
)));
807 /* OK, this is kind of wacky. The standard says that we call
808 terminate when the exception handling mechanism, after
809 completing evaluation of the expression to be thrown but
810 before the exception is caught (_except.throw_), calls a
811 user function that exits via an uncaught exception.
813 So we have to protect the actual initialization of the
814 exception object with terminate(), but evaluate the
815 expression first. Since there could be temps in the
816 expression, we need to handle that, too. We also expand
817 the call to __cxa_allocate_exception first (which doesn't
818 matter, since it can't throw). */
820 /* Allocate the space for the exception. */
821 allocate_expr
= do_allocate_exception (temp_type
);
822 allocate_expr
= get_target_expr (allocate_expr
);
823 ptr
= TARGET_EXPR_SLOT (allocate_expr
);
824 TARGET_EXPR_CLEANUP (allocate_expr
) = do_free_exception (ptr
);
825 CLEANUP_EH_ONLY (allocate_expr
) = 1;
827 object
= build_nop (build_pointer_type (temp_type
), ptr
);
828 object
= cp_build_indirect_ref (object
, RO_NULL
, tf_warning_or_error
);
830 /* And initialize the exception object. */
831 if (CLASS_TYPE_P (temp_type
))
833 int flags
= LOOKUP_NORMAL
| LOOKUP_ONLYCONVERTING
;
834 vec
<tree
, va_gc
> *exp_vec
;
836 /* Under C++0x [12.8/16 class.copy], a thrown lvalue is sometimes
837 treated as an rvalue for the purposes of overload resolution
838 to favor move constructors over copy constructors. */
839 if (/* Must be a local, automatic variable. */
841 && DECL_CONTEXT (exp
) == current_function_decl
842 && ! TREE_STATIC (exp
)
843 /* The variable must not have the `volatile' qualifier. */
844 && !(cp_type_quals (TREE_TYPE (exp
)) & TYPE_QUAL_VOLATILE
))
845 flags
= flags
| LOOKUP_PREFER_RVALUE
;
847 /* Call the copy constructor. */
848 exp_vec
= make_tree_vector_single (exp
);
849 exp
= (build_special_member_call
850 (object
, complete_ctor_identifier
, &exp_vec
,
851 TREE_TYPE (object
), flags
, tf_warning_or_error
));
852 release_tree_vector (exp_vec
);
853 if (exp
== error_mark_node
)
855 error (" in thrown expression");
856 return error_mark_node
;
861 tmp
= decay_conversion (exp
, tf_warning_or_error
);
862 if (tmp
== error_mark_node
)
863 return error_mark_node
;
864 exp
= build2 (INIT_EXPR
, temp_type
, object
, tmp
);
867 /* Mark any cleanups from the initialization as MUST_NOT_THROW, since
868 they are run after the exception object is initialized. */
869 cp_walk_tree_without_duplicates (&exp
, wrap_cleanups_r
, 0);
871 /* Prepend the allocation. */
872 exp
= build2 (COMPOUND_EXPR
, TREE_TYPE (exp
), allocate_expr
, exp
);
874 /* Force all the cleanups to be evaluated here so that we don't have
875 to do them during unwinding. */
876 exp
= build1 (CLEANUP_POINT_EXPR
, void_type_node
, exp
);
878 throw_type
= build_eh_type_type (prepare_eh_type (TREE_TYPE (object
)));
881 if (type_build_dtor_call (TREE_TYPE (object
)))
883 tree fn
= lookup_fnfields (TYPE_BINFO (TREE_TYPE (object
)),
884 complete_dtor_identifier
, 0);
885 fn
= BASELINK_FUNCTIONS (fn
);
887 if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (object
)))
889 cxx_mark_addressable (fn
);
890 /* Pretend it's a normal function. */
891 cleanup
= build1 (ADDR_EXPR
, cleanup_type
, fn
);
894 if (cleanup
== NULL_TREE
)
895 cleanup
= build_int_cst (cleanup_type
, 0);
897 /* ??? Indicate that this function call throws throw_type. */
898 tmp
= cp_build_function_call_nary (fn
, tf_warning_or_error
,
899 ptr
, throw_type
, cleanup
, NULL_TREE
);
901 /* Tack on the initialization stuff. */
902 exp
= build2 (COMPOUND_EXPR
, TREE_TYPE (tmp
), exp
, tmp
);
906 /* Rethrow current exception. */
908 tree fn
= get_identifier ("__cxa_rethrow");
909 if (!get_global_value_if_present (fn
, &fn
))
911 /* Declare void __cxa_rethrow (void). */
912 fn
= push_throw_library_fn
913 (fn
, build_function_type_list (void_type_node
, NULL_TREE
));
917 apply_tm_attr (fn
, get_identifier ("transaction_pure"));
919 /* ??? Indicate that this function call allows exceptions of the type
920 of the enclosing catch block (if known). */
921 exp
= cp_build_function_call_vec (fn
, NULL
, tf_warning_or_error
);
924 exp
= build1 (THROW_EXPR
, void_type_node
, exp
);
925 SET_EXPR_LOCATION (exp
, input_location
);
930 /* Make sure TYPE is complete, pointer to complete, reference to
931 complete, or pointer to cv void. Issue diagnostic on failure.
932 Return the zero on failure and nonzero on success. FROM can be
933 the expr or decl from whence TYPE came, if available. */
936 complete_ptr_ref_or_void_ptr_p (tree type
, tree from
)
940 /* Check complete. */
941 type
= complete_type_or_else (type
, from
);
945 /* Or a pointer or ref to one, or cv void *. */
946 is_ptr
= TYPE_PTR_P (type
);
947 if (is_ptr
|| TREE_CODE (type
) == REFERENCE_TYPE
)
949 tree core
= TREE_TYPE (type
);
951 if (is_ptr
&& VOID_TYPE_P (core
))
953 else if (!complete_type_or_else (core
, from
))
959 /* If IS_THROW is true return truth-value if T is an expression admissible
960 in throw-expression, i.e. if it is not of incomplete type or a pointer/
961 reference to such a type or of an abstract class type.
962 If IS_THROW is false, likewise for a catch parameter, same requirements
963 for its type plus rvalue reference type is also not admissible. */
966 is_admissible_throw_operand_or_catch_parameter (tree t
, bool is_throw
)
968 tree expr
= is_throw
? t
: NULL_TREE
;
969 tree type
= TREE_TYPE (t
);
971 /* C++11 [except.handle] The exception-declaration shall not denote
972 an incomplete type, an abstract class type, or an rvalue reference
975 /* 15.1/4 [...] The type of the throw-expression shall not be an
976 incomplete type, or a pointer or a reference to an incomplete
977 type, other than void*, const void*, volatile void*, or
978 const volatile void*. Except for these restriction and the
979 restrictions on type matching mentioned in 15.3, the operand
980 of throw is treated exactly as a function argument in a call
981 (5.2.2) or the operand of a return statement. */
982 if (!complete_ptr_ref_or_void_ptr_p (type
, expr
))
985 /* 10.4/3 An abstract class shall not be used as a parameter type,
986 as a function return type or as type of an explicit
988 else if (abstract_virtuals_error (is_throw
? ACU_THROW
: ACU_CATCH
, type
))
991 && TREE_CODE (type
) == REFERENCE_TYPE
992 && TYPE_REF_IS_RVALUE (type
))
994 error ("cannot declare catch parameter to be of rvalue "
995 "reference type %qT", type
);
998 else if (variably_modified_type_p (type
, NULL_TREE
))
1001 error ("cannot throw expression of type %qT because it involves "
1002 "types of variable size", type
);
1004 error ("cannot catch type %qT because it involves types of "
1005 "variable size", type
);
1012 /* Returns nonzero if FN is a declaration of a standard C library
1013 function which is known not to throw.
1015 [lib.res.on.exception.handling]: None of the functions from the
1016 Standard C library shall report an error by throwing an
1017 exception, unless it calls a program-supplied function that
1018 throws an exception. */
1023 nothrow_libfn_p (const_tree fn
)
1027 if (TREE_PUBLIC (fn
)
1028 && DECL_EXTERNAL (fn
)
1029 && DECL_NAMESPACE_SCOPE_P (fn
)
1030 && DECL_EXTERN_C_P (fn
))
1033 /* Can't be a C library function. */
1036 /* Being a C library function, DECL_ASSEMBLER_NAME == DECL_NAME
1037 unless the system headers are playing rename tricks, and if
1038 they are, we don't want to be confused by them. */
1039 id
= DECL_NAME (fn
);
1040 return !!libc_name_p (IDENTIFIER_POINTER (id
), IDENTIFIER_LENGTH (id
));
1043 /* Returns nonzero if an exception of type FROM will be caught by a
1044 handler for type TO, as per [except.handle]. */
1047 can_convert_eh (tree to
, tree from
)
1049 to
= non_reference (to
);
1050 from
= non_reference (from
);
1052 if (TYPE_PTR_P (to
) && TYPE_PTR_P (from
))
1054 to
= TREE_TYPE (to
);
1055 from
= TREE_TYPE (from
);
1057 if (! at_least_as_qualified_p (to
, from
))
1060 if (VOID_TYPE_P (to
))
1063 /* Else fall through. */
1066 if (CLASS_TYPE_P (to
) && CLASS_TYPE_P (from
)
1067 && publicly_uniquely_derived_p (to
, from
))
1073 /* Check whether any of the handlers in I are shadowed by another handler
1074 accepting TYPE. Note that the shadowing may not be complete; even if
1075 an exception of type B would be caught by a handler for A, there could
1076 be a derived class C for which A is an ambiguous base but B is not, so
1077 the handler for B would catch an exception of type C. */
1080 check_handlers_1 (tree master
, tree_stmt_iterator i
)
1082 tree type
= TREE_TYPE (master
);
1084 for (; !tsi_end_p (i
); tsi_next (&i
))
1086 tree handler
= tsi_stmt (i
);
1087 if (TREE_TYPE (handler
) && can_convert_eh (type
, TREE_TYPE (handler
)))
1089 warning_at (EXPR_LOCATION (handler
), 0,
1090 "exception of type %qT will be caught",
1091 TREE_TYPE (handler
));
1092 warning_at (EXPR_LOCATION (master
), 0,
1093 " by earlier handler for %qT", type
);
1099 /* Given a STATEMENT_LIST of HANDLERs, make sure that they're OK. */
1102 check_handlers (tree handlers
)
1104 tree_stmt_iterator i
;
1106 /* If we don't have a STATEMENT_LIST, then we've just got one
1107 handler, and thus nothing to warn about. */
1108 if (TREE_CODE (handlers
) != STATEMENT_LIST
)
1111 i
= tsi_start (handlers
);
1115 tree handler
= tsi_stmt (i
);
1118 /* No more handlers; nothing to shadow. */
1121 if (TREE_TYPE (handler
) == NULL_TREE
)
1122 permerror (EXPR_LOCATION (handler
), "%<...%>"
1123 " handler must be the last handler for its try block");
1125 check_handlers_1 (handler
, i
);
1129 /* walk_tree helper for finish_noexcept_expr. Returns non-null if the
1130 expression *TP causes the noexcept operator to evaluate to false.
1132 5.3.7 [expr.noexcept]: The result of the noexcept operator is false if
1133 in a potentially-evaluated context the expression would contain
1134 * a potentially evaluated call to a function, member function,
1135 function pointer, or member function pointer that does not have a
1136 non-throwing exception-specification (15.4),
1137 * a potentially evaluated throw-expression (15.1),
1138 * a potentially evaluated dynamic_cast expression dynamic_cast<T>(v),
1139 where T is a reference type, that requires a run-time check (5.2.7), or
1140 * a potentially evaluated typeid expression (5.2.8) applied to a glvalue
1141 expression whose type is a polymorphic class type (10.3). */
1144 check_noexcept_r (tree
*tp
, int * /*walk_subtrees*/, void * /*data*/)
1147 enum tree_code code
= TREE_CODE (t
);
1148 if ((code
== CALL_EXPR
&& CALL_EXPR_FN (t
))
1149 || code
== AGGR_INIT_EXPR
)
1151 /* We can only use the exception specification of the called function
1152 for determining the value of a noexcept expression; we can't use
1153 TREE_NOTHROW, as it might have a different value in another
1154 translation unit, creating ODR problems.
1156 We could use TREE_NOTHROW (t) for !TREE_PUBLIC fns, though... */
1157 tree fn
= (code
== AGGR_INIT_EXPR
1158 ? AGGR_INIT_EXPR_FN (t
) : CALL_EXPR_FN (t
));
1159 tree type
= TREE_TYPE (TREE_TYPE (fn
));
1162 if (TREE_CODE (fn
) == ADDR_EXPR
)
1163 fn
= TREE_OPERAND (fn
, 0);
1164 if (TREE_CODE (fn
) == FUNCTION_DECL
)
1166 /* We do use TREE_NOTHROW for ABI internals like __dynamic_cast,
1167 and for C library functions known not to throw. */
1168 if (DECL_EXTERN_C_P (fn
)
1169 && (DECL_ARTIFICIAL (fn
)
1170 || nothrow_libfn_p (fn
)))
1171 return TREE_NOTHROW (fn
) ? NULL_TREE
: fn
;
1172 /* A call to a constexpr function is noexcept if the call
1173 is a constant expression. */
1174 if (DECL_DECLARED_CONSTEXPR_P (fn
)
1175 && is_sub_constant_expr (t
))
1178 if (!TYPE_NOTHROW_P (type
))
1185 /* If a function that causes a noexcept-expression to be false isn't
1186 defined yet, remember it and check it for TREE_NOTHROW again at EOF. */
1188 typedef struct GTY(()) pending_noexcept
{
1192 static GTY(()) vec
<pending_noexcept
, va_gc
> *pending_noexcept_checks
;
1194 /* FN is a FUNCTION_DECL that caused a noexcept-expr to be false. Warn if
1198 maybe_noexcept_warning (tree fn
)
1200 if (TREE_NOTHROW (fn
))
1202 warning (OPT_Wnoexcept
, "noexcept-expression evaluates to %<false%> "
1203 "because of a call to %qD", fn
);
1204 warning (OPT_Wnoexcept
, "but %q+D does not throw; perhaps "
1205 "it should be declared %<noexcept%>", fn
);
1209 /* Check any functions that weren't defined earlier when they caused a
1210 noexcept expression to evaluate to false. */
1213 perform_deferred_noexcept_checks (void)
1216 pending_noexcept
*p
;
1217 location_t saved_loc
= input_location
;
1218 FOR_EACH_VEC_SAFE_ELT (pending_noexcept_checks
, i
, p
)
1220 input_location
= p
->loc
;
1221 maybe_noexcept_warning (p
->fn
);
1223 input_location
= saved_loc
;
1226 /* Evaluate noexcept ( EXPR ). */
1229 finish_noexcept_expr (tree expr
, tsubst_flags_t complain
)
1231 if (expr
== error_mark_node
)
1232 return error_mark_node
;
1234 if (processing_template_decl
)
1235 return build_min (NOEXCEPT_EXPR
, boolean_type_node
, expr
);
1237 return (expr_noexcept_p (expr
, complain
)
1238 ? boolean_true_node
: boolean_false_node
);
1241 /* Returns whether EXPR is noexcept, possibly warning if allowed by
1245 expr_noexcept_p (tree expr
, tsubst_flags_t complain
)
1249 if (expr
== error_mark_node
)
1252 fn
= cp_walk_tree_without_duplicates (&expr
, check_noexcept_r
, 0);
1255 if ((complain
& tf_warning
) && warn_noexcept
1256 && TREE_CODE (fn
) == FUNCTION_DECL
)
1258 if (!DECL_INITIAL (fn
))
1260 /* Not defined yet; check again at EOF. */
1261 pending_noexcept p
= {fn
, input_location
};
1262 vec_safe_push (pending_noexcept_checks
, p
);
1265 maybe_noexcept_warning (fn
);
1273 /* Return true iff SPEC is throw() or noexcept(true). */
1276 nothrow_spec_p (const_tree spec
)
1278 gcc_assert (!DEFERRED_NOEXCEPT_SPEC_P (spec
));
1279 if (spec
== NULL_TREE
1280 || TREE_VALUE (spec
) != NULL_TREE
1281 || spec
== noexcept_false_spec
)
1283 if (TREE_PURPOSE (spec
) == NULL_TREE
1284 || spec
== noexcept_true_spec
)
1286 gcc_assert (processing_template_decl
1287 || TREE_PURPOSE (spec
) == error_mark_node
);
1291 /* For FUNCTION_TYPE or METHOD_TYPE, true if NODE is noexcept. This is the
1292 case for things declared noexcept(true) and, with -fnothrow-opt, for
1293 throw() functions. */
1296 type_noexcept_p (const_tree type
)
1298 tree spec
= TYPE_RAISES_EXCEPTIONS (type
);
1299 gcc_assert (!DEFERRED_NOEXCEPT_SPEC_P (spec
));
1300 if (flag_nothrow_opt
)
1301 return nothrow_spec_p (spec
);
1303 return spec
== noexcept_true_spec
;
1306 /* For FUNCTION_TYPE or METHOD_TYPE, true if NODE can throw any type,
1307 i.e. no exception-specification or noexcept(false). */
1310 type_throw_all_p (const_tree type
)
1312 tree spec
= TYPE_RAISES_EXCEPTIONS (type
);
1313 gcc_assert (!DEFERRED_NOEXCEPT_SPEC_P (spec
));
1314 return spec
== NULL_TREE
|| spec
== noexcept_false_spec
;
1317 /* Create a representation of the noexcept-specification with
1318 constant-expression of EXPR. COMPLAIN is as for tsubst. */
1321 build_noexcept_spec (tree expr
, int complain
)
1323 /* This isn't part of the signature, so don't bother trying to evaluate
1324 it until instantiation. */
1325 if (!processing_template_decl
&& TREE_CODE (expr
) != DEFERRED_NOEXCEPT
)
1327 expr
= perform_implicit_conversion_flags (boolean_type_node
, expr
,
1330 expr
= cxx_constant_value (expr
);
1332 if (TREE_CODE (expr
) == INTEGER_CST
)
1334 if (operand_equal_p (expr
, boolean_true_node
, 0))
1335 return noexcept_true_spec
;
1338 gcc_checking_assert (operand_equal_p (expr
, boolean_false_node
, 0));
1339 return noexcept_false_spec
;
1342 else if (expr
== error_mark_node
)
1343 return error_mark_node
;
1346 gcc_assert (processing_template_decl
1347 || TREE_CODE (expr
) == DEFERRED_NOEXCEPT
);
1348 return build_tree_list (expr
, NULL_TREE
);
1352 /* Returns a noexcept-specifier to be evaluated later, for an
1353 implicitly-declared or explicitly defaulted special member function. */
1356 unevaluated_noexcept_spec (void)
1359 if (spec
== NULL_TREE
)
1360 spec
= build_noexcept_spec (make_node (DEFERRED_NOEXCEPT
), tf_none
);
1364 /* Returns a TRY_CATCH_EXPR that will put TRY_LIST and CATCH_LIST in the
1365 TRY and CATCH locations. CATCH_LIST must be a STATEMENT_LIST */
1368 create_try_catch_expr (tree try_expr
, tree catch_list
)
1370 location_t loc
= EXPR_LOCATION (try_expr
);
1372 append_to_statement_list (do_begin_catch (), &catch_list
);
1373 append_to_statement_list (build_throw (NULL_TREE
), &catch_list
);
1374 tree catch_tf_expr
= build_stmt (loc
, TRY_FINALLY_EXPR
, catch_list
,
1375 do_end_catch (NULL_TREE
));
1376 catch_list
= build2 (CATCH_EXPR
, void_type_node
, NULL_TREE
,
1378 tree try_catch_expr
= build_stmt (loc
, TRY_CATCH_EXPR
, try_expr
, catch_list
);
1379 return try_catch_expr
;
1382 #include "gt-cp-except.h"