2 * Copyright 2010-2011 PathScale, Inc. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are met:
7 * 1. Redistributions of source code must retain the above copyright notice,
8 * this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright notice,
11 * this list of conditions and the following disclaimer in the documentation
12 * and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS
15 * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
16 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
17 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
18 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
19 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
20 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
21 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
22 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
23 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
24 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36 #define _MTHREADIFY_PTHREADS 1
37 #include <minix/mthread.h>
38 #endif /* !defined(__minix) */
45 #pragma weak pthread_key_create
46 #pragma weak pthread_setspecific
47 #pragma weak pthread_getspecific
48 #pragma weak pthread_once
49 #ifdef LIBCXXRT_WEAK_LOCKS
50 #pragma weak pthread_mutex_lock
51 #define pthread_mutex_lock(mtx) do {\
52 if (pthread_mutex_lock) pthread_mutex_lock(mtx);\
54 #pragma weak pthread_mutex_unlock
55 #define pthread_mutex_unlock(mtx) do {\
56 if (pthread_mutex_unlock) pthread_mutex_unlock(mtx);\
58 #pragma weak pthread_cond_signal
59 #define pthread_cond_signal(cv) do {\
60 if (pthread_cond_signal) pthread_cond_signal(cv);\
62 #pragma weak pthread_cond_wait
63 #define pthread_cond_wait(cv, mtx) do {\
64 if (pthread_cond_wait) pthread_cond_wait(cv, mtx);\
68 using namespace ABI_NAMESPACE
;
71 * Saves the result of the landing pad that we have found. For ARM, this is
72 * stored in the generic unwind structure, while on other platforms it is
73 * stored in the C++ exception.
75 static void saveLandingPad(struct _Unwind_Context
*context
,
76 struct _Unwind_Exception
*ucb
,
77 struct __cxa_exception
*ex
,
79 dw_eh_ptr_t landingPad
)
82 // On ARM, we store the saved exception in the generic part of the structure
83 ucb
->barrier_cache
.sp
= _Unwind_GetGR(context
, 13);
84 ucb
->barrier_cache
.bitpattern
[1] = (uint32_t)selector
;
85 ucb
->barrier_cache
.bitpattern
[3] = (uint32_t)landingPad
;
87 // Cache the results for the phase 2 unwind, if we found a handler
88 // and this is not a foreign exception.
91 ex
->handlerSwitchValue
= selector
;
92 ex
->catchTemp
= landingPad
;
97 * Loads the saved landing pad. Returns 1 on success, 0 on failure.
99 static int loadLandingPad(struct _Unwind_Context
*context
,
100 struct _Unwind_Exception
*ucb
,
101 struct __cxa_exception
*ex
,
102 unsigned long *selector
,
103 dw_eh_ptr_t
*landingPad
)
106 *selector
= ucb
->barrier_cache
.bitpattern
[1];
107 *landingPad
= (dw_eh_ptr_t
)ucb
->barrier_cache
.bitpattern
[3];
112 *selector
= ex
->handlerSwitchValue
;
113 *landingPad
= (dw_eh_ptr_t
)ex
->catchTemp
;
120 static inline _Unwind_Reason_Code
continueUnwinding(struct _Unwind_Exception
*ex
,
121 struct _Unwind_Context
*context
)
124 if (__gnu_unwind_frame(ex
, context
) != _URC_OK
) { return _URC_FAILURE
; }
126 return _URC_CONTINUE_UNWIND
;
130 extern "C" void __cxa_free_exception(void *thrown_exception
);
131 extern "C" void __cxa_free_dependent_exception(void *thrown_exception
);
132 extern "C" void* __dynamic_cast(const void *sub
,
133 const __class_type_info
*src
,
134 const __class_type_info
*dst
,
135 ptrdiff_t src2dst_offset
);
138 * The type of a handler that has been found.
145 * A cleanup - the exception will propagate through this frame, but code
146 * must be run when this happens.
150 * A catch statement. The exception will not propagate past this frame
151 * (without an explicit rethrow).
157 * Per-thread info required by the runtime. We store a single structure
158 * pointer in thread-local storage, because this tends to be a scarce resource
159 * and it's impolite to steal all of it and not leave any for the rest of the
162 * Instances of this structure are allocated lazily - at most one per thread -
163 * and are destroyed on thread termination.
165 struct __cxa_thread_info
167 /** The termination handler for this thread. */
168 terminate_handler terminateHandler
;
169 /** The unexpected exception handler for this thread. */
170 unexpected_handler unexpectedHandler
;
172 * The number of emergency buffers held by this thread. This is 0 in
173 * normal operation - the emergency buffers are only used when malloc()
174 * fails to return memory for allocating an exception. Threads are not
175 * permitted to hold more than 4 emergency buffers (as per recommendation
176 * in ABI spec [3.3.1]).
178 int emergencyBuffersHeld
;
180 * The exception currently running in a cleanup.
182 _Unwind_Exception
*currentCleanup
;
184 * Our state with respect to foreign exceptions. Usually none, set to
185 * caught if we have just caught an exception and rethrown if we are
193 } foreign_exception_state
;
195 * The public part of this structure, accessible from outside of this
198 __cxa_eh_globals globals
;
201 * Dependent exception. This
203 struct __cxa_dependent_exception
206 void *primaryException
;
208 std::type_info
*exceptionType
;
209 void (*exceptionDestructor
) (void *);
210 unexpected_handler unexpectedHandler
;
211 terminate_handler terminateHandler
;
212 __cxa_exception
*nextException
;
215 _Unwind_Exception
*nextCleanup
;
218 int handlerSwitchValue
;
219 const char *actionRecord
;
220 const char *languageSpecificData
;
224 void *primaryException
;
226 _Unwind_Exception unwindHeader
;
236 virtual ~exception() throw();
237 virtual const char* what() const throw();
243 * Class of exceptions to distinguish between this and other exception types.
245 * The first four characters are the vendor ID. Currently, we use GNUC,
246 * because we aim for ABI-compatibility with the GNU implementation, and
247 * various checks may test for equality of the class, which is incorrect.
249 static const uint64_t exception_class
=
250 EXCEPTION_CLASS('G', 'N', 'U', 'C', 'C', '+', '+', '\0');
252 * Class used for dependent exceptions.
254 static const uint64_t dependent_exception_class
=
255 EXCEPTION_CLASS('G', 'N', 'U', 'C', 'C', '+', '+', '\x01');
257 * The low four bytes of the exception class, indicating that we conform to the
258 * Itanium C++ ABI. This is currently unused, but should be used in the future
259 * if we change our exception class, to allow this library and libsupc++ to be
260 * linked to the same executable and both to interoperate.
262 static const uint32_t abi_exception_class
=
263 GENERIC_EXCEPTION_CLASS('C', '+', '+', '\0');
265 static bool isCXXException(uint64_t cls
)
267 return (cls
== exception_class
) || (cls
== dependent_exception_class
);
270 static bool isDependentException(uint64_t cls
)
272 return cls
== dependent_exception_class
;
275 static __cxa_exception
*exceptionFromPointer(void *ex
)
277 return (__cxa_exception
*)((char*)ex
-
278 offsetof(struct __cxa_exception
, unwindHeader
));
280 static __cxa_exception
*realExceptionFromException(__cxa_exception
*ex
)
282 if (!isDependentException(ex
->unwindHeader
.exception_class
)) { return ex
; }
283 return ((__cxa_exception
*)(((__cxa_dependent_exception
*)ex
)->primaryException
))-1;
289 // Forward declaration of standard library terminate() function used to
291 void terminate(void);
294 using namespace ABI_NAMESPACE
;
298 /** The global termination handler. */
299 static terminate_handler terminateHandler
= abort
;
300 /** The global unexpected exception handler. */
301 static unexpected_handler unexpectedHandler
= std::terminate
;
303 /** Key used for thread-local data. */
304 static pthread_key_t eh_key
;
308 * Cleanup function, allowing foreign exception handlers to correctly destroy
309 * this exception if they catch it.
311 static void exception_cleanup(_Unwind_Reason_Code reason
,
312 struct _Unwind_Exception
*ex
)
314 __cxa_free_exception((void*)ex
);
316 static void dependent_exception_cleanup(_Unwind_Reason_Code reason
,
317 struct _Unwind_Exception
*ex
)
320 __cxa_free_dependent_exception((void*)ex
);
324 * Recursively walk a list of exceptions and delete them all in post-order.
326 static void free_exception_list(__cxa_exception
*ex
)
328 if (0 != ex
->nextException
)
330 free_exception_list(ex
->nextException
);
332 // __cxa_free_exception() expects to be passed the thrown object, which
333 // immediately follows the exception, not the exception itself
334 __cxa_free_exception(ex
+1);
338 * Cleanup function called when a thread exists to make certain that all of the
339 * per-thread data is deleted.
341 static void thread_cleanup(void* thread_info
)
343 __cxa_thread_info
*info
= (__cxa_thread_info
*)thread_info
;
344 if (info
->globals
.caughtExceptions
)
346 // If this is a foreign exception, ask it to clean itself up.
347 if (info
->foreign_exception_state
!= __cxa_thread_info::none
)
349 _Unwind_Exception
*e
= (_Unwind_Exception
*)info
->globals
.caughtExceptions
;
350 e
->exception_cleanup(_URC_FOREIGN_EXCEPTION_CAUGHT
, e
);
354 free_exception_list(info
->globals
.caughtExceptions
);
362 * Once control used to protect the key creation.
364 static pthread_once_t once_control
= PTHREAD_ONCE_INIT
;
367 * We may not be linked against a full pthread implementation. If we're not,
368 * then we need to fake the thread-local storage by storing 'thread-local'
369 * things in a global.
373 * Thread-local storage for a single-threaded program.
375 static __cxa_thread_info singleThreadInfo
;
379 static void init_key(void)
381 if ((0 == pthread_key_create
) ||
382 (0 == pthread_setspecific
) ||
383 (0 == pthread_getspecific
))
388 pthread_key_create(&eh_key
, thread_cleanup
);
389 pthread_setspecific(eh_key
, (void*)0x42);
390 fakeTLS
= (pthread_getspecific(eh_key
) != (void*)0x42);
391 pthread_setspecific(eh_key
, 0);
395 * Returns the thread info structure, creating it if it is not already created.
397 static __cxa_thread_info
*thread_info()
399 if ((0 == pthread_once
) || pthread_once(&once_control
, init_key
))
403 if (fakeTLS
) { return &singleThreadInfo
; }
404 __cxa_thread_info
*info
= (__cxa_thread_info
*)pthread_getspecific(eh_key
);
407 info
= (__cxa_thread_info
*)calloc(1, sizeof(__cxa_thread_info
));
408 pthread_setspecific(eh_key
, info
);
413 * Fast version of thread_info(). May fail if thread_info() is not called on
414 * this thread at least once already.
416 static __cxa_thread_info
*thread_info_fast()
418 if (fakeTLS
) { return &singleThreadInfo
; }
419 return (__cxa_thread_info
*)pthread_getspecific(eh_key
);
422 * ABI function returning the __cxa_eh_globals structure.
424 extern "C" __cxa_eh_globals
*ABI_NAMESPACE::__cxa_get_globals(void)
426 return &(thread_info()->globals
);
429 * Version of __cxa_get_globals() assuming that __cxa_get_globals() has already
430 * been called at least once by this thread.
432 extern "C" __cxa_eh_globals
*ABI_NAMESPACE::__cxa_get_globals_fast(void)
434 return &(thread_info_fast()->globals
);
438 * An emergency allocation reserved for when malloc fails. This is treated as
439 * 16 buffers of 1KB each.
441 static char emergency_buffer
[16384];
443 * Flag indicating whether each buffer is allocated.
445 static bool buffer_allocated
[16];
447 * Lock used to protect emergency allocation.
449 static pthread_mutex_t emergency_malloc_lock
= PTHREAD_MUTEX_INITIALIZER
;
451 * Condition variable used to wait when two threads are both trying to use the
452 * emergency malloc() buffer at once.
454 static pthread_cond_t emergency_malloc_wait
= PTHREAD_COND_INITIALIZER
;
457 * Allocates size bytes from the emergency allocation mechanism, if possible.
458 * This function will fail if size is over 1KB or if this thread already has 4
459 * emergency buffers. If all emergency buffers are allocated, it will sleep
460 * until one becomes available.
462 static char *emergency_malloc(size_t size
)
464 if (size
> 1024) { return 0; }
466 __cxa_thread_info
*info
= thread_info();
467 // Only 4 emergency buffers allowed per thread!
468 if (info
->emergencyBuffersHeld
> 3) { return 0; }
470 pthread_mutex_lock(&emergency_malloc_lock
);
474 // While we were sleeping on the lock, another thread might have free'd
475 // enough memory for us to use, so try the allocation again - no point
476 // using the emergency buffer if there is some real memory that we can
478 void *m
= calloc(1, size
);
481 pthread_mutex_unlock(&emergency_malloc_lock
);
484 for (int i
=0 ; i
<16 ; i
++)
486 if (!buffer_allocated
[i
])
489 buffer_allocated
[i
] = true;
493 // If there still isn't a buffer available, then sleep on the condition
494 // variable. This will be signalled when another thread releases one
495 // of the emergency buffers.
498 pthread_cond_wait(&emergency_malloc_wait
, &emergency_malloc_lock
);
501 pthread_mutex_unlock(&emergency_malloc_lock
);
502 info
->emergencyBuffersHeld
++;
503 return emergency_buffer
+ (1024 * buffer
);
507 * Frees a buffer returned by emergency_malloc().
509 * Note: Neither this nor emergency_malloc() is particularly efficient. This
510 * should not matter, because neither will be called in normal operation - they
511 * are only used when the program runs out of memory, which should not happen
514 static void emergency_malloc_free(char *ptr
)
517 // Find the buffer corresponding to this pointer.
518 for (int i
=0 ; i
<16 ; i
++)
520 if (ptr
== (void*)(emergency_buffer
+ (1024 * i
)))
527 "Trying to free something that is not an emergency buffer!");
528 // emergency_malloc() is expected to return 0-initialized data. We don't
529 // zero the buffer when allocating it, because the static buffers will
530 // begin life containing 0 values.
531 memset((void*)ptr
, 0, 1024);
532 // Signal the condition variable to wake up any threads that are blocking
533 // waiting for some space in the emergency buffer
534 pthread_mutex_lock(&emergency_malloc_lock
);
535 // In theory, we don't need to do this with the lock held. In practice,
536 // our array of bools will probably be updated using 32-bit or 64-bit
537 // memory operations, so this update may clobber adjacent values.
538 buffer_allocated
[buffer
] = false;
539 pthread_cond_signal(&emergency_malloc_wait
);
540 pthread_mutex_unlock(&emergency_malloc_lock
);
543 static char *alloc_or_die(size_t size
)
545 char *buffer
= (char*)calloc(1, size
);
547 // If calloc() doesn't want to give us any memory, try using an emergency
551 buffer
= emergency_malloc(size
);
552 // This is only reached if the allocation is greater than 1KB, and
553 // anyone throwing objects that big really should know better.
556 fprintf(stderr
, "Out of memory attempting to allocate exception\n");
562 static void free_exception(char *e
)
564 // If this allocation is within the address range of the emergency buffer,
565 // don't call free() because it was not allocated with malloc()
566 if ((e
> emergency_buffer
) &&
567 (e
< (emergency_buffer
+ sizeof(emergency_buffer
))))
569 emergency_malloc_free(e
);
578 * Allocates an exception structure. Returns a pointer to the space that can
579 * be used to store an object of thrown_size bytes. This function will use an
580 * emergency buffer if malloc() fails, and may block if there are no such
583 extern "C" void *__cxa_allocate_exception(size_t thrown_size
)
585 size_t size
= thrown_size
+ sizeof(__cxa_exception
);
586 char *buffer
= alloc_or_die(size
);
587 return buffer
+sizeof(__cxa_exception
);
590 extern "C" void *__cxa_allocate_dependent_exception(void)
592 size_t size
= sizeof(__cxa_dependent_exception
);
593 char *buffer
= alloc_or_die(size
);
594 return buffer
+sizeof(__cxa_dependent_exception
);
598 * __cxa_free_exception() is called when an exception was thrown in between
599 * calling __cxa_allocate_exception() and actually throwing the exception.
600 * This happens when the object's copy constructor throws an exception.
602 * In this implementation, it is also called by __cxa_end_catch() and during
605 extern "C" void __cxa_free_exception(void *thrown_exception
)
607 __cxa_exception
*ex
= ((__cxa_exception
*)thrown_exception
) - 1;
608 // Free the object that was thrown, calling its destructor
609 if (0 != ex
->exceptionDestructor
)
613 ex
->exceptionDestructor(thrown_exception
);
617 // FIXME: Check that this is really what the spec says to do.
622 free_exception((char*)ex
);
625 static void releaseException(__cxa_exception
*exception
)
627 if (isDependentException(exception
->unwindHeader
.exception_class
))
629 __cxa_free_dependent_exception(exception
+1);
632 if (__sync_sub_and_fetch(&exception
->referenceCount
, 1) == 0)
634 // __cxa_free_exception() expects to be passed the thrown object,
635 // which immediately follows the exception, not the exception
637 __cxa_free_exception(exception
+1);
641 void __cxa_free_dependent_exception(void *thrown_exception
)
643 __cxa_dependent_exception
*ex
= ((__cxa_dependent_exception
*)thrown_exception
) - 1;
644 assert(isDependentException(ex
->unwindHeader
.exception_class
));
645 if (ex
->primaryException
)
647 releaseException(realExceptionFromException((__cxa_exception
*)ex
));
649 free_exception((char*)ex
);
653 * Callback function used with _Unwind_Backtrace().
655 * Prints a stack trace. Used only for debugging help.
657 * Note: As of FreeBSD 8.1, dladd() still doesn't work properly, so this only
658 * correctly prints function names from public, relocatable, symbols.
660 static _Unwind_Reason_Code
trace(struct _Unwind_Context
*context
, void *c
)
664 dladdr((void*)(uintptr_t)__cxa_current_exception_type
, &myinfo
);
665 void *ip
= (void*)_Unwind_GetIP(context
);
667 if (dladdr(ip
, &info
) != 0)
669 if (mylookup
== 0 || strcmp(info
.dli_fname
, myinfo
.dli_fname
) != 0)
671 printf("%p:%s() in %s\n", ip
, info
.dli_sname
, info
.dli_fname
);
674 return _URC_CONTINUE_UNWIND
;
678 * Report a failure that occurred when attempting to throw an exception.
680 * If the failure happened by falling off the end of the stack without finding
681 * a handler, prints a back trace before aborting.
683 static void report_failure(_Unwind_Reason_Code err
, __cxa_exception
*thrown_exception
)
688 case _URC_FATAL_PHASE1_ERROR
:
689 fprintf(stderr
, "Fatal error during phase 1 unwinding\n");
692 case _URC_FATAL_PHASE2_ERROR
:
693 fprintf(stderr
, "Fatal error during phase 2 unwinding\n");
696 case _URC_END_OF_STACK
:
697 fprintf(stderr
, "Terminating due to uncaught exception %p",
698 (void*)thrown_exception
);
699 thrown_exception
= realExceptionFromException(thrown_exception
);
700 static const __class_type_info
*e_ti
=
701 static_cast<const __class_type_info
*>(&typeid(std::exception
));
702 const __class_type_info
*throw_ti
=
703 dynamic_cast<const __class_type_info
*>(thrown_exception
->exceptionType
);
707 (std::exception
*)e_ti
->cast_to((void*)(thrown_exception
+1),
711 fprintf(stderr
, " '%s'", e
->what());
715 size_t bufferSize
= 128;
716 char *demangled
= (char*)malloc(bufferSize
);
717 const char *mangled
= thrown_exception
->exceptionType
->name();
719 demangled
= __cxa_demangle(mangled
, demangled
, &bufferSize
, &status
);
720 fprintf(stderr
, " of type %s\n",
721 status
== 0 ? (const char*)demangled
: mangled
);
722 if (status
== 0) { free(demangled
); }
723 // Print a back trace if no handler is found.
724 // TODO: Make this optional
725 _Unwind_Backtrace(trace
, 0);
731 static void throw_exception(__cxa_exception
*ex
)
733 __cxa_thread_info
*info
= thread_info();
734 ex
->unexpectedHandler
= info
->unexpectedHandler
;
735 if (0 == ex
->unexpectedHandler
)
737 ex
->unexpectedHandler
= unexpectedHandler
;
739 ex
->terminateHandler
= info
->terminateHandler
;
740 if (0 == ex
->terminateHandler
)
742 ex
->terminateHandler
= terminateHandler
;
744 info
->globals
.uncaughtExceptions
++;
746 _Unwind_Reason_Code err
= _Unwind_RaiseException(&ex
->unwindHeader
);
747 // The _Unwind_RaiseException() function should not return, it should
748 // unwind the stack past this function. If it does return, then something
750 report_failure(err
, ex
);
755 * ABI function for throwing an exception. Takes the object to be thrown (the
756 * pointer returned by __cxa_allocate_exception()), the type info for the
757 * pointee, and the destructor (if there is one) as arguments.
759 extern "C" void __cxa_throw(void *thrown_exception
,
760 std::type_info
*tinfo
,
763 __cxa_exception
*ex
= ((__cxa_exception
*)thrown_exception
) - 1;
765 ex
->referenceCount
= 1;
766 ex
->exceptionType
= tinfo
;
768 ex
->exceptionDestructor
= dest
;
770 ex
->unwindHeader
.exception_class
= exception_class
;
771 ex
->unwindHeader
.exception_cleanup
= exception_cleanup
;
776 extern "C" void __cxa_rethrow_primary_exception(void* thrown_exception
)
778 if (NULL
== thrown_exception
) { return; }
780 __cxa_exception
*original
= exceptionFromPointer(thrown_exception
);
781 __cxa_dependent_exception
*ex
= ((__cxa_dependent_exception
*)__cxa_allocate_dependent_exception())-1;
783 ex
->primaryException
= thrown_exception
;
784 __cxa_increment_exception_refcount(thrown_exception
);
786 ex
->exceptionType
= original
->exceptionType
;
787 ex
->unwindHeader
.exception_class
= dependent_exception_class
;
788 ex
->unwindHeader
.exception_cleanup
= dependent_exception_cleanup
;
790 throw_exception((__cxa_exception
*)ex
);
793 extern "C" void *__cxa_current_primary_exception(void)
795 __cxa_eh_globals
* globals
= __cxa_get_globals();
796 __cxa_exception
*ex
= globals
->caughtExceptions
;
798 if (0 == ex
) { return NULL
; }
799 ex
= realExceptionFromException(ex
);
800 __sync_fetch_and_add(&ex
->referenceCount
, 1);
804 extern "C" void __cxa_increment_exception_refcount(void* thrown_exception
)
806 if (NULL
== thrown_exception
) { return; }
807 __cxa_exception
*ex
= ((__cxa_exception
*)thrown_exception
) - 1;
808 if (isDependentException(ex
->unwindHeader
.exception_class
)) { return; }
809 __sync_fetch_and_add(&ex
->referenceCount
, 1);
811 extern "C" void __cxa_decrement_exception_refcount(void* thrown_exception
)
813 if (NULL
== thrown_exception
) { return; }
814 __cxa_exception
*ex
= ((__cxa_exception
*)thrown_exception
) - 1;
815 releaseException(ex
);
819 * ABI function. Rethrows the current exception. Does not remove the
820 * exception from the stack or decrement its handler count - the compiler is
821 * expected to set the landing pad for this function to the end of the catch
822 * block, and then call _Unwind_Resume() to continue unwinding once
823 * __cxa_end_catch() has been called and any cleanup code has been run.
825 extern "C" void __cxa_rethrow()
827 __cxa_thread_info
*ti
= thread_info();
828 __cxa_eh_globals
*globals
= &ti
->globals
;
829 // Note: We don't remove this from the caught list here, because
830 // __cxa_end_catch will be called when we unwind out of the try block. We
831 // could probably make this faster by providing an alternative rethrow
832 // function and ensuring that all cleanup code is run before calling it, so
833 // we can skip the top stack frame when unwinding.
834 __cxa_exception
*ex
= globals
->caughtExceptions
;
839 "Attempting to rethrow an exception that doesn't exist!\n");
843 if (ti
->foreign_exception_state
!= __cxa_thread_info::none
)
845 ti
->foreign_exception_state
= __cxa_thread_info::rethrown
;
846 _Unwind_Exception
*e
= (_Unwind_Exception
*)ex
;
847 _Unwind_Reason_Code err
= _Unwind_Resume_or_Rethrow(e
);
848 report_failure(err
, ex
);
852 assert(ex
->handlerCount
> 0 && "Rethrowing uncaught exception!");
854 // ex->handlerCount will be decremented in __cxa_end_catch in enclosing
857 // Make handler count negative. This will tell __cxa_end_catch that
858 // exception was rethrown and exception object should not be destroyed
859 // when handler count become zero
860 ex
->handlerCount
= -ex
->handlerCount
;
862 // Continue unwinding the stack with this exception. This should unwind to
863 // the place in the caller where __cxa_end_catch() is called. The caller
864 // will then run cleanup code and bounce the exception back with
866 _Unwind_Reason_Code err
= _Unwind_Resume_or_Rethrow(&ex
->unwindHeader
);
867 report_failure(err
, ex
);
871 * Returns the type_info object corresponding to the filter.
873 static std::type_info
*get_type_info_entry(_Unwind_Context
*context
,
877 // Get the address of the record in the table.
878 dw_eh_ptr_t record
= lsda
->type_table
-
879 dwarf_size_of_fixed_size_field(lsda
->type_table_encoding
)*filter
;
881 dw_eh_ptr_t start
= record
;
882 // Read the value, but it's probably an indirect reference...
883 int64_t offset
= read_value(lsda
->type_table_encoding
, &record
);
885 // (If the entry is 0, don't try to dereference it. That would be bad.)
886 if (offset
== 0) { return 0; }
888 // ...so we need to resolve it
889 return (std::type_info
*)resolve_indirect_value(context
,
890 lsda
->type_table_encoding
, offset
, start
);
896 * Checks the type signature found in a handler against the type of the thrown
897 * object. If ex is 0 then it is assumed to be a foreign exception and only
900 static bool check_type_signature(__cxa_exception
*ex
,
901 const std::type_info
*type
,
904 void *exception_ptr
= (void*)(ex
+1);
905 const std::type_info
*ex_type
= ex
? ex
->exceptionType
: 0;
907 bool is_ptr
= ex
? ex_type
->__is_pointer_p() : false;
910 exception_ptr
= *(void**)exception_ptr
;
912 // Always match a catchall, even with a foreign exception
914 // Note: A 0 here is a catchall, not a cleanup, so we return true to
915 // indicate that we found a catch.
920 adjustedPtr
= exception_ptr
;
925 if (0 == ex
) { return false; }
927 // If the types are the same, no casting is needed.
928 if (*type
== *ex_type
)
930 adjustedPtr
= exception_ptr
;
935 if (type
->__do_catch(ex_type
, &exception_ptr
, 1))
937 adjustedPtr
= exception_ptr
;
944 * Checks whether the exception matches the type specifiers in this action
945 * record. If the exception only matches cleanups, then this returns false.
946 * If it matches a catch (including a catchall) then it returns true.
948 * The selector argument is used to return the selector that is passed in the
949 * second exception register when installing the context.
951 static handler_type
check_action_record(_Unwind_Context
*context
,
953 dw_eh_ptr_t action_record
,
955 unsigned long *selector
,
958 if (!action_record
) { return handler_cleanup
; }
959 handler_type found
= handler_none
;
960 while (action_record
)
962 int filter
= read_sleb128(&action_record
);
963 dw_eh_ptr_t action_record_offset_base
= action_record
;
964 int displacement
= read_sleb128(&action_record
);
965 action_record
= displacement
?
966 action_record_offset_base
+ displacement
: 0;
967 // We only check handler types for C++ exceptions - foreign exceptions
968 // are only allowed for cleanups and catchalls.
971 std::type_info
*handler_type
= get_type_info_entry(context
, lsda
, filter
);
972 if (check_type_signature(ex
, handler_type
, adjustedPtr
))
975 return handler_catch
;
978 else if (filter
< 0 && 0 != ex
)
980 bool matched
= false;
984 std::type_info
*handler_type
= get_type_info_entry(context
, lsda
, filter
--);
987 if (check_type_signature(ex
, handler_type
, adjustedPtr
))
992 handler_type
= get_type_info_entry(context
, lsda
, filter
--);
995 unsigned char *type_index
= ((unsigned char*)lsda
->type_table
- filter
- 1);
998 std::type_info
*handler_type
= get_type_info_entry(context
, lsda
, *(type_index
++));
999 // If the exception spec matches a permitted throw type for
1000 // this function, don't report a handler - we are allowed to
1001 // propagate this exception out.
1002 if (check_type_signature(ex
, handler_type
, adjustedPtr
))
1009 if (matched
) { continue; }
1010 // If we don't find an allowed exception spec, we need to install
1011 // the context for this action. The landing pad will then call the
1012 // unexpected exception function. Treat this as a catch
1013 return handler_catch
;
1015 else if (filter
== 0)
1018 found
= handler_cleanup
;
1024 static void pushCleanupException(_Unwind_Exception
*exceptionObject
,
1025 __cxa_exception
*ex
)
1028 __cxa_thread_info
*info
= thread_info_fast();
1032 if (ex
->cleanupCount
> 1)
1034 assert(exceptionObject
== info
->currentCleanup
);
1037 ex
->nextCleanup
= info
->currentCleanup
;
1039 info
->currentCleanup
= exceptionObject
;
1044 * The exception personality function. This is referenced in the unwinding
1045 * DWARF metadata and is called by the unwind library for each C++ stack frame
1046 * containing catch or cleanup code.
1049 BEGIN_PERSONALITY_FUNCTION(__gxx_personality_v0
)
1050 // This personality function is for version 1 of the ABI. If you use it
1051 // with a future version of the ABI, it won't know what to do, so it
1052 // reports a fatal error and give up before it breaks anything.
1055 return _URC_FATAL_PHASE1_ERROR
;
1057 __cxa_exception
*ex
= 0;
1058 __cxa_exception
*realEx
= 0;
1060 // If this exception is throw by something else then we can't make any
1061 // assumptions about its layout beyond the fields declared in
1062 // _Unwind_Exception.
1063 bool foreignException
= !isCXXException(exceptionClass
);
1065 // If this isn't a foreign exception, then we have a C++ exception structure
1066 if (!foreignException
)
1068 ex
= exceptionFromPointer(exceptionObject
);
1069 realEx
= realExceptionFromException(ex
);
1072 unsigned char *lsda_addr
=
1073 (unsigned char*)_Unwind_GetLanguageSpecificData(context
);
1075 // No LSDA implies no landing pads - try the next frame
1076 if (0 == lsda_addr
) { return continueUnwinding(exceptionObject
, context
); }
1078 // These two variables define how the exception will be handled.
1079 dwarf_eh_action action
= {0};
1080 unsigned long selector
= 0;
1082 // During the search phase, we do a complete lookup. If we return
1083 // _URC_HANDLER_FOUND, then the phase 2 unwind will call this function with
1084 // a _UA_HANDLER_FRAME action, telling us to install the handler frame. If
1085 // we return _URC_CONTINUE_UNWIND, we may be called again later with a
1086 // _UA_CLEANUP_PHASE action for this frame.
1088 // The point of the two-stage unwind allows us to entirely avoid any stack
1089 // unwinding if there is no handler. If there are just cleanups found,
1090 // then we can just panic call an abort function.
1092 // Matching a handler is much more expensive than matching a cleanup,
1093 // because we don't need to bother doing type comparisons (or looking at
1094 // the type table at all) for a cleanup. This means that there is no need
1095 // to cache the result of finding a cleanup, because it's (quite) quick to
1096 // look it up again from the action table.
1097 if (actions
& _UA_SEARCH_PHASE
)
1099 struct dwarf_eh_lsda lsda
= parse_lsda(context
, lsda_addr
);
1101 if (!dwarf_eh_find_callsite(context
, &lsda
, &action
))
1103 // EH range not found. This happens if exception is thrown and not
1104 // caught inside a cleanup (destructor). We should call
1105 // terminate() in this case. The catchTemp (landing pad) field of
1106 // exception object will contain null when personality function is
1107 // called with _UA_HANDLER_FRAME action for phase 2 unwinding.
1108 return _URC_HANDLER_FOUND
;
1111 handler_type found_handler
= check_action_record(context
, &lsda
,
1112 action
.action_record
, realEx
, &selector
, ex
->adjustedPtr
);
1113 // If there's no action record, we've only found a cleanup, so keep
1114 // searching for something real
1115 if (found_handler
== handler_catch
)
1117 // Cache the results for the phase 2 unwind, if we found a handler
1118 // and this is not a foreign exception.
1121 saveLandingPad(context
, exceptionObject
, ex
, selector
, action
.landing_pad
);
1122 ex
->languageSpecificData
= (const char*)lsda_addr
;
1123 ex
->actionRecord
= (const char*)action
.action_record
;
1124 // ex->adjustedPtr is set when finding the action record.
1126 return _URC_HANDLER_FOUND
;
1128 return continueUnwinding(exceptionObject
, context
);
1132 // If this is a foreign exception, we didn't have anywhere to cache the
1133 // lookup stuff, so we need to do it again. If this is either a forced
1134 // unwind, a foreign exception, or a cleanup, then we just install the
1135 // context for a cleanup.
1136 if (!(actions
& _UA_HANDLER_FRAME
))
1139 struct dwarf_eh_lsda lsda
= parse_lsda(context
, lsda_addr
);
1140 dwarf_eh_find_callsite(context
, &lsda
, &action
);
1141 if (0 == action
.landing_pad
) { return continueUnwinding(exceptionObject
, context
); }
1142 handler_type found_handler
= check_action_record(context
, &lsda
,
1143 action
.action_record
, realEx
, &selector
, ex
->adjustedPtr
);
1144 // Ignore handlers this time.
1145 if (found_handler
!= handler_cleanup
) { return continueUnwinding(exceptionObject
, context
); }
1146 pushCleanupException(exceptionObject
, ex
);
1148 else if (foreignException
)
1150 struct dwarf_eh_lsda lsda
= parse_lsda(context
, lsda_addr
);
1151 dwarf_eh_find_callsite(context
, &lsda
, &action
);
1152 check_action_record(context
, &lsda
, action
.action_record
, realEx
,
1153 &selector
, ex
->adjustedPtr
);
1155 else if (ex
->catchTemp
== 0)
1157 // Uncaught exception in cleanup, calling terminate
1162 // Restore the saved info if we saved some last time.
1163 loadLandingPad(context
, exceptionObject
, ex
, &selector
, &action
.landing_pad
);
1165 ex
->handlerSwitchValue
= 0;
1169 _Unwind_SetIP(context
, (unsigned long)action
.landing_pad
);
1170 _Unwind_SetGR(context
, __builtin_eh_return_data_regno(0),
1171 (unsigned long)exceptionObject
);
1172 _Unwind_SetGR(context
, __builtin_eh_return_data_regno(1), selector
);
1174 return _URC_INSTALL_CONTEXT
;
1178 * ABI function called when entering a catch statement. The argument is the
1179 * pointer passed out of the personality function. This is always the start of
1180 * the _Unwind_Exception object. The return value for this function is the
1181 * pointer to the caught exception, which is either the adjusted pointer (for
1182 * C++ exceptions) of the unadjusted pointer (for foreign exceptions).
1184 #if __GNUC__ > 3 && __GNUC_MINOR__ > 2
1185 extern "C" void *__cxa_begin_catch(void *e
) throw()
1187 extern "C" void *__cxa_begin_catch(void *e
)
1190 // We can't call the fast version here, because if the first exception that
1191 // we see is a foreign exception then we won't have called it yet.
1192 __cxa_thread_info
*ti
= thread_info();
1193 __cxa_eh_globals
*globals
= &ti
->globals
;
1194 globals
->uncaughtExceptions
--;
1195 _Unwind_Exception
*exceptionObject
= (_Unwind_Exception
*)e
;
1197 if (isCXXException(exceptionObject
->exception_class
))
1199 __cxa_exception
*ex
= exceptionFromPointer(exceptionObject
);
1201 if (ex
->handlerCount
== 0)
1203 // Add this to the front of the list of exceptions being handled
1204 // and increment its handler count so that it won't be deleted
1206 ex
->nextException
= globals
->caughtExceptions
;
1207 globals
->caughtExceptions
= ex
;
1210 if (ex
->handlerCount
< 0)
1212 // Rethrown exception is catched before end of catch block.
1213 // Clear the rethrow flag (make value positive) - we are allowed
1214 // to delete this exception at the end of the catch block, as long
1215 // as it isn't thrown again later.
1227 // __cxa_begin_catch() <- we are here
1230 ex
->handlerCount
= -ex
->handlerCount
+ 1;
1236 ti
->foreign_exception_state
= __cxa_thread_info::none
;
1238 return ex
->adjustedPtr
;
1242 // If this is a foreign exception, then we need to be able to
1243 // store it. We can't chain foreign exceptions, so we give up
1244 // if there are already some outstanding ones.
1245 if (globals
->caughtExceptions
!= 0)
1249 globals
->caughtExceptions
= (__cxa_exception
*)exceptionObject
;
1250 ti
->foreign_exception_state
= __cxa_thread_info::caught
;
1252 // exceptionObject is the pointer to the _Unwind_Exception within the
1253 // __cxa_exception. The throw object is after this
1254 return ((char*)exceptionObject
+ sizeof(_Unwind_Exception
));
1260 * ABI function called when exiting a catch block. This will free the current
1261 * exception if it is no longer referenced in other catch blocks.
1263 extern "C" void __cxa_end_catch()
1265 // We can call the fast version here because the slow version is called in
1266 // __cxa_throw(), which must have been called before we end a catch block
1267 __cxa_thread_info
*ti
= thread_info_fast();
1268 __cxa_eh_globals
*globals
= &ti
->globals
;
1269 __cxa_exception
*ex
= globals
->caughtExceptions
;
1271 assert(0 != ex
&& "Ending catch when no exception is on the stack!");
1273 if (ti
->foreign_exception_state
!= __cxa_thread_info::none
)
1275 globals
->caughtExceptions
= 0;
1276 if (ti
->foreign_exception_state
!= __cxa_thread_info::rethrown
)
1278 _Unwind_Exception
*e
= (_Unwind_Exception
*)ti
->globals
.caughtExceptions
;
1279 e
->exception_cleanup(_URC_FOREIGN_EXCEPTION_CAUGHT
, e
);
1281 ti
->foreign_exception_state
= __cxa_thread_info::none
;
1285 bool deleteException
= true;
1287 if (ex
->handlerCount
< 0)
1289 // exception was rethrown. Exception should not be deleted even if
1290 // handlerCount become zero.
1300 // __cxa_end_catch(); <- we are here
1306 deleteException
= false;
1313 if (ex
->handlerCount
== 0)
1315 globals
->caughtExceptions
= ex
->nextException
;
1316 if (deleteException
)
1318 releaseException(ex
);
1324 * ABI function. Returns the type of the current exception.
1326 extern "C" std::type_info
*__cxa_current_exception_type()
1328 __cxa_eh_globals
*globals
= __cxa_get_globals();
1329 __cxa_exception
*ex
= globals
->caughtExceptions
;
1330 return ex
? ex
->exceptionType
: 0;
1334 * ABI function, called when an exception specification is violated.
1336 * This function does not return.
1338 extern "C" void __cxa_call_unexpected(void*exception
)
1340 _Unwind_Exception
*exceptionObject
= (_Unwind_Exception
*)exception
;
1341 if (exceptionObject
->exception_class
== exception_class
)
1343 __cxa_exception
*ex
= exceptionFromPointer(exceptionObject
);
1344 if (ex
->unexpectedHandler
)
1346 ex
->unexpectedHandler();
1347 // Should not be reached.
1352 // Should not be reached.
1357 * ABI function, returns the adjusted pointer to the exception object.
1359 extern "C" void *__cxa_get_exception_ptr(void *exceptionObject
)
1361 return exceptionFromPointer(exceptionObject
)->adjustedPtr
;
1365 * As an extension, we provide the ability for the unexpected and terminate
1366 * handlers to be thread-local. We default to the standards-compliant
1367 * behaviour where they are global.
1369 static bool thread_local_handlers
= false;
1375 * Sets whether unexpected and terminate handlers should be thread-local.
1377 void set_use_thread_local_handlers(bool flag
) throw()
1379 thread_local_handlers
= flag
;
1382 * Sets a thread-local unexpected handler.
1384 unexpected_handler
set_unexpected(unexpected_handler f
) throw()
1386 static __cxa_thread_info
*info
= thread_info();
1387 unexpected_handler old
= info
->unexpectedHandler
;
1388 info
->unexpectedHandler
= f
;
1392 * Sets a thread-local terminate handler.
1394 terminate_handler
set_terminate(terminate_handler f
) throw()
1396 static __cxa_thread_info
*info
= thread_info();
1397 terminate_handler old
= info
->terminateHandler
;
1398 info
->terminateHandler
= f
;
1406 * Sets the function that will be called when an exception specification is
1409 unexpected_handler
set_unexpected(unexpected_handler f
) throw()
1411 if (thread_local_handlers
) { return pathscale::set_unexpected(f
); }
1413 return ATOMIC_SWAP(&unexpectedHandler
, f
);
1416 * Sets the function that is called to terminate the program.
1418 terminate_handler
set_terminate(terminate_handler f
) throw()
1420 if (thread_local_handlers
) { return pathscale::set_terminate(f
); }
1422 return ATOMIC_SWAP(&terminateHandler
, f
);
1425 * Terminates the program, calling a custom terminate implementation if
1430 static __cxa_thread_info
*info
= thread_info();
1431 if (0 != info
&& 0 != info
->terminateHandler
)
1433 info
->terminateHandler();
1434 // Should not be reached - a terminate handler is not expected to
1441 * Called when an unexpected exception is encountered (i.e. an exception
1442 * violates an exception specification). This calls abort() unless a
1443 * custom handler has been set..
1447 static __cxa_thread_info
*info
= thread_info();
1448 if (0 != info
&& 0 != info
->unexpectedHandler
)
1450 info
->unexpectedHandler();
1451 // Should not be reached - a terminate handler is not expected to
1455 unexpectedHandler();
1458 * Returns whether there are any exceptions currently being thrown that
1459 * have not been caught. This can occur inside a nested catch statement.
1461 bool uncaught_exception() throw()
1463 __cxa_thread_info
*info
= thread_info();
1464 return info
->globals
.uncaughtExceptions
!= 0;
1467 * Returns the current unexpected handler.
1469 unexpected_handler
get_unexpected() throw()
1471 __cxa_thread_info
*info
= thread_info();
1472 if (info
->unexpectedHandler
)
1474 return info
->unexpectedHandler
;
1476 return ATOMIC_LOAD(&unexpectedHandler
);
1479 * Returns the current terminate handler.
1481 terminate_handler
get_terminate() throw()
1483 __cxa_thread_info
*info
= thread_info();
1484 if (info
->terminateHandler
)
1486 return info
->terminateHandler
;
1488 return ATOMIC_LOAD(&terminateHandler
);
1492 extern "C" _Unwind_Exception
*__cxa_get_cleanup(void)
1494 __cxa_thread_info
*info
= thread_info_fast();
1495 _Unwind_Exception
*exceptionObject
= info
->currentCleanup
;
1496 if (isCXXException(exceptionObject
->exception_class
))
1498 __cxa_exception
*ex
= exceptionFromPointer(exceptionObject
);
1500 if (ex
->cleanupCount
== 0)
1502 info
->currentCleanup
= ex
->nextCleanup
;
1503 ex
->nextCleanup
= 0;
1508 info
->currentCleanup
= 0;
1510 return exceptionObject
;
1514 ".pushsection .text.__cxa_end_cleanup \n"
1515 ".global __cxa_end_cleanup \n"
1516 ".type __cxa_end_cleanup, \"function\" \n"
1517 "__cxa_end_cleanup: \n"
1518 " push {r1, r2, r3, r4} \n"
1519 " bl __cxa_get_cleanup \n"
1520 " push {r1, r2, r3, r4} \n"
1521 " b _Unwind_Resume \n"