1 /* The implementation of exception handling primitives for Objective-C.
2 Copyright (C) 2004, 2005, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it
7 under the terms of the GNU General Public License as published by the
8 Free Software Foundation; either version 3, or (at your option) any
11 GCC is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
14 License for more details.
16 Under Section 7 of GPL version 3, you are granted additional
17 permissions described in the GCC Runtime Library Exception, version
18 3.1, as published by the Free Software Foundation.
20 You should have received a copy of the GNU General Public License and
21 a copy of the GCC Runtime Library Exception along with this program;
22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 <http://www.gnu.org/licenses/>. */
27 #include "objc/objc-api.h"
28 #include "objc/objc-exception.h"
30 #include "unwind-pe.h"
32 /* This hook allows libraries to sepecify special actions when an
33 exception is thrown without a handler in place. This is deprecated
34 in favour of objc_set_uncaught_exception_handler ().
36 void (*_objc_unexpected_exception
) (id exception
); /* !T:SAFE */
39 /* 'is_kind_of_exception_matcher' is our default exception matcher -
40 it determines if the object 'exception' is of class 'catch_class',
44 is_kind_of_exception_matcher (Class catch_class
, id exception
)
46 /* NULL catch_class is catch-all (eg, @catch (id object)). */
47 if (catch_class
== Nil
)
50 /* If exception is nil (eg, @throw nil;), then it can only be catched
51 * by a catch-all (eg, @catch (id object)).
57 for (c
= exception
->class_pointer
; c
!= Nil
;
58 c
= class_get_super_class (c
))
65 /* The exception matcher currently in use. */
66 static objc_exception_matcher
67 __objc_exception_matcher
= is_kind_of_exception_matcher
;
69 objc_exception_matcher
70 objc_set_exception_matcher (objc_exception_matcher new_matcher
)
72 objc_exception_matcher old_matcher
= __objc_exception_matcher
;
73 __objc_exception_matcher
= new_matcher
;
77 /* The uncaught exception handler currently in use. */
78 static objc_uncaught_exception_handler
79 __objc_uncaught_exception_handler
= NULL
;
81 objc_uncaught_exception_handler
82 objc_set_uncaught_exception_handler (objc_uncaught_exception_handler
85 objc_uncaught_exception_handler old_handler
86 = __objc_uncaught_exception_handler
;
87 __objc_uncaught_exception_handler
= new_handler
;
93 #ifdef __ARM_EABI_UNWINDER__
95 const _Unwind_Exception_Class __objc_exception_class
96 = {'G', 'N', 'U', 'C', 'O', 'B', 'J', 'C'};
100 /* This is the exception class we report -- "GNUCOBJC". */
101 static const _Unwind_Exception_Class __objc_exception_class
102 = ((((((((_Unwind_Exception_Class
) 'G'
103 << 8 | (_Unwind_Exception_Class
) 'N')
104 << 8 | (_Unwind_Exception_Class
) 'U')
105 << 8 | (_Unwind_Exception_Class
) 'C')
106 << 8 | (_Unwind_Exception_Class
) 'O')
107 << 8 | (_Unwind_Exception_Class
) 'B')
108 << 8 | (_Unwind_Exception_Class
) 'J')
109 << 8 | (_Unwind_Exception_Class
) 'C');
113 /* This is the object that is passed around by the Objective C runtime
114 to represent the exception in flight. */
118 /* This bit is needed in order to interact with the unwind runtime. */
119 struct _Unwind_Exception base
;
121 /* The actual object we want to throw. Note: must come immediately after
125 #ifdef __ARM_EABI_UNWINDER__
126 /* Note: we use the barrier cache defined in the unwind control block for
129 /* Cache some internal unwind data between phase 1 and phase 2. */
130 _Unwind_Ptr landingPad
;
131 int handlerSwitchValue
;
137 struct lsda_header_info
141 _Unwind_Ptr ttype_base
;
142 const unsigned char *TType
;
143 const unsigned char *action_table
;
144 unsigned char ttype_encoding
;
145 unsigned char call_site_encoding
;
148 static const unsigned char *
149 parse_lsda_header (struct _Unwind_Context
*context
, const unsigned char *p
,
150 struct lsda_header_info
*info
)
153 unsigned char lpstart_encoding
;
155 info
->Start
= (context
? _Unwind_GetRegionStart (context
) : 0);
157 /* Find @LPStart, the base to which landing pad offsets are relative. */
158 lpstart_encoding
= *p
++;
159 if (lpstart_encoding
!= DW_EH_PE_omit
)
160 p
= read_encoded_value (context
, lpstart_encoding
, p
, &info
->LPStart
);
162 info
->LPStart
= info
->Start
;
164 /* Find @TType, the base of the handler and exception spec type data. */
165 info
->ttype_encoding
= *p
++;
166 if (info
->ttype_encoding
!= DW_EH_PE_omit
)
168 p
= read_uleb128 (p
, &tmp
);
169 info
->TType
= p
+ tmp
;
174 /* The encoding and length of the call-site table; the action table
175 immediately follows. */
176 info
->call_site_encoding
= *p
++;
177 p
= read_uleb128 (p
, &tmp
);
178 info
->action_table
= p
+ tmp
;
183 #ifdef __ARM_EABI_UNWINDER__
186 get_ttype_entry (struct lsda_header_info
*info
, _uleb128_t i
)
190 ptr
= (_Unwind_Ptr
) (info
->TType
- (i
* 4));
191 ptr
= _Unwind_decode_target2 (ptr
);
194 return objc_get_class ((const char *) ptr
);
202 get_ttype_entry (struct lsda_header_info
*info
, _Unwind_Word i
)
206 i
*= size_of_encoded_value (info
->ttype_encoding
);
207 read_encoded_value_with_base (info
->ttype_encoding
, info
->ttype_base
,
208 info
->TType
- i
, &ptr
);
210 /* NULL ptr means catch-all. */
212 return objc_get_class ((const char *) ptr
);
219 /* Using a different personality function name causes link failures
220 when trying to mix code using different exception handling models. */
221 #ifdef SJLJ_EXCEPTIONS
222 #define PERSONALITY_FUNCTION __gnu_objc_personality_sj0
223 #define __builtin_eh_return_data_regno(x) x
225 #define PERSONALITY_FUNCTION __gnu_objc_personality_v0
228 #ifdef __ARM_EABI_UNWINDER__
230 #define CONTINUE_UNWINDING \
233 if (__gnu_unwind_frame(ue_header, context) != _URC_OK) \
234 return _URC_FAILURE; \
235 return _URC_CONTINUE_UNWIND; \
240 PERSONALITY_FUNCTION (_Unwind_State state
,
241 struct _Unwind_Exception
*ue_header
,
242 struct _Unwind_Context
*context
)
245 #define CONTINUE_UNWINDING return _URC_CONTINUE_UNWIND
248 PERSONALITY_FUNCTION (int version
,
249 _Unwind_Action actions
,
250 _Unwind_Exception_Class exception_class
,
251 struct _Unwind_Exception
*ue_header
,
252 struct _Unwind_Context
*context
)
255 struct ObjcException
*xh
= (struct ObjcException
*) ue_header
;
257 struct lsda_header_info info
;
258 const unsigned char *language_specific_data
;
259 const unsigned char *action_record
;
260 const unsigned char *p
;
261 _Unwind_Ptr landing_pad
, ip
;
262 int handler_switch_value
;
263 int saw_cleanup
= 0, saw_handler
, foreign_exception
;
265 int ip_before_insn
= 0;
267 #ifdef __ARM_EABI_UNWINDER__
268 _Unwind_Action actions
;
270 switch (state
& _US_ACTION_MASK
)
272 case _US_VIRTUAL_UNWIND_FRAME
:
273 actions
= _UA_SEARCH_PHASE
;
276 case _US_UNWIND_FRAME_STARTING
:
277 actions
= _UA_CLEANUP_PHASE
;
278 if (!(state
& _US_FORCE_UNWIND
)
279 && ue_header
->barrier_cache
.sp
== _Unwind_GetGR (context
, 13))
280 actions
|= _UA_HANDLER_FRAME
;
283 case _US_UNWIND_FRAME_RESUME
:
290 actions
|= state
& _US_FORCE_UNWIND
;
292 /* TODO: Foreign exceptions need some attention (e.g. rethrowing doesn't
294 foreign_exception
= 0;
296 /* The dwarf unwinder assumes the context structure holds things like the
297 function and LSDA pointers. The ARM implementation caches these in
298 the exception header (UCB). To avoid rewriting everything we make the
299 virtual IP register point at the UCB. */
300 ip
= (_Unwind_Ptr
) ue_header
;
301 _Unwind_SetGR (context
, 12, ip
);
303 #else /* !__ARM_EABI_UNWINDER. */
304 /* Interface version check. */
306 return _URC_FATAL_PHASE1_ERROR
;
308 foreign_exception
= (exception_class
!= __objc_exception_class
);
311 /* Shortcut for phase 2 found handler for domestic exception. */
312 if (actions
== (_UA_CLEANUP_PHASE
| _UA_HANDLER_FRAME
)
313 && !foreign_exception
)
315 #ifdef __ARM_EABI_UNWINDER__
316 handler_switch_value
= (int) ue_header
->barrier_cache
.bitpattern
[1];
317 landing_pad
= (_Unwind_Ptr
) ue_header
->barrier_cache
.bitpattern
[3];
319 handler_switch_value
= xh
->handlerSwitchValue
;
320 landing_pad
= xh
->landingPad
;
322 goto install_context
;
325 language_specific_data
= (const unsigned char *)
326 _Unwind_GetLanguageSpecificData (context
);
328 /* If no LSDA, then there are no handlers or cleanups. */
329 if (! language_specific_data
)
332 /* Parse the LSDA header. */
333 p
= parse_lsda_header (context
, language_specific_data
, &info
);
334 info
.ttype_base
= base_of_encoded_value (info
.ttype_encoding
, context
);
335 #ifdef HAVE_GETIPINFO
336 ip
= _Unwind_GetIPInfo (context
, &ip_before_insn
);
338 ip
= _Unwind_GetIP (context
);
344 handler_switch_value
= 0;
346 #ifdef SJLJ_EXCEPTIONS
347 /* The given "IP" is an index into the call-site table, with two
348 exceptions -- -1 means no-action, and 0 means terminate. But
349 since we're using uleb128 values, we've not got random access
352 return _URC_CONTINUE_UNWIND
;
355 _uleb128_t cs_lp
, cs_action
;
358 p
= read_uleb128 (p
, &cs_lp
);
359 p
= read_uleb128 (p
, &cs_action
);
363 /* Can never have null landing pad for sjlj -- that would have
364 been indicated by a -1 call site index. */
365 landing_pad
= cs_lp
+ 1;
367 action_record
= info
.action_table
+ cs_action
- 1;
368 goto found_something
;
371 /* Search the call-site table for the action associated with this IP. */
372 while (p
< info
.action_table
)
374 _Unwind_Ptr cs_start
, cs_len
, cs_lp
;
375 _uleb128_t cs_action
;
377 /* Note that all call-site encodings are "absolute" displacements. */
378 p
= read_encoded_value (0, info
.call_site_encoding
, p
, &cs_start
);
379 p
= read_encoded_value (0, info
.call_site_encoding
, p
, &cs_len
);
380 p
= read_encoded_value (0, info
.call_site_encoding
, p
, &cs_lp
);
381 p
= read_uleb128 (p
, &cs_action
);
383 /* The table is sorted, so if we've passed the ip, stop. */
384 if (ip
< info
.Start
+ cs_start
)
385 p
= info
.action_table
;
386 else if (ip
< info
.Start
+ cs_start
+ cs_len
)
389 landing_pad
= info
.LPStart
+ cs_lp
;
391 action_record
= info
.action_table
+ cs_action
- 1;
392 goto found_something
;
395 #endif /* SJLJ_EXCEPTIONS */
397 /* If ip is not present in the table, C++ would call terminate. */
398 /* ??? As with Java, it's perhaps better to tweek the LSDA to
399 that no-action is mapped to no-entry. */
406 if (landing_pad
== 0)
408 /* If ip is present, and has a null landing pad, there are
409 no cleanups or handlers to be run. */
411 else if (action_record
== 0)
413 /* If ip is present, has a non-null landing pad, and a null
414 action table offset, then there are only cleanups present.
415 Cleanups use a zero switch value, as set above. */
420 /* Otherwise we have a catch handler. */
421 _sleb128_t ar_filter
, ar_disp
;
426 p
= read_sleb128 (p
, &ar_filter
);
427 read_sleb128 (p
, &ar_disp
);
431 /* Zero filter values are cleanups. */
435 /* During forced unwinding, we only run cleanups. With a
436 foreign exception class, we have no class info to match. */
437 else if ((actions
& _UA_FORCE_UNWIND
) || foreign_exception
)
440 else if (ar_filter
> 0)
442 /* Positive filter values are handlers. */
444 Class catch_type
= get_ttype_entry (&info
, ar_filter
);
446 if ((*__objc_exception_matcher
) (catch_type
, xh
->value
))
448 handler_switch_value
= ar_filter
;
455 /* Negative filter values are exception specifications,
456 which Objective-C does not use. */
462 action_record
= p
+ ar_disp
;
466 if (! saw_handler
&& ! saw_cleanup
)
469 if (actions
& _UA_SEARCH_PHASE
)
474 /* For domestic exceptions, we cache data from phase 1 for phase 2. */
475 if (!foreign_exception
)
477 #ifdef __ARM_EABI_UNWINDER__
478 ue_header
->barrier_cache
.sp
= _Unwind_GetGR (context
, 13);
479 ue_header
->barrier_cache
.bitpattern
[1] = (_uw
) handler_switch_value
;
480 ue_header
->barrier_cache
.bitpattern
[3] = (_uw
) landing_pad
;
482 xh
->handlerSwitchValue
= handler_switch_value
;
483 xh
->landingPad
= landing_pad
;
486 return _URC_HANDLER_FOUND
;
490 if (saw_cleanup
== 0)
492 return_object
= xh
->value
;
493 if (!(actions
& _UA_SEARCH_PHASE
))
494 _Unwind_DeleteException(&xh
->base
);
497 _Unwind_SetGR (context
, __builtin_eh_return_data_regno (0),
498 __builtin_extend_pointer (saw_cleanup
? xh
: return_object
));
499 _Unwind_SetGR (context
, __builtin_eh_return_data_regno (1),
500 handler_switch_value
);
501 _Unwind_SetIP (context
, landing_pad
);
502 return _URC_INSTALL_CONTEXT
;
506 __objc_exception_cleanup (_Unwind_Reason_Code code
__attribute__((unused
)),
507 struct _Unwind_Exception
*exc
)
513 objc_exception_throw (id exception
)
515 struct ObjcException
*header
= calloc (1, sizeof (*header
));
517 memcpy (&header
->base
.exception_class
, &__objc_exception_class
,
518 sizeof (__objc_exception_class
));
519 header
->base
.exception_cleanup
= __objc_exception_cleanup
;
520 header
->value
= exception
;
522 #ifdef SJLJ_EXCEPTIONS
523 _Unwind_SjLj_RaiseException (&header
->base
);
525 _Unwind_RaiseException (&header
->base
);
528 /* No exception handler was installed. Call the uncaught exception
529 handler if any is defined.
531 if (__objc_uncaught_exception_handler
!= 0)
533 (*__objc_uncaught_exception_handler
) (exception
);
536 /* As a last resort support the old, deprecated way of setting an
537 uncaught exception handler.
539 if (_objc_unexpected_exception
!= 0)
541 (*_objc_unexpected_exception
) (exception
);