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.
38 #pragma weak pthread_key_create
39 #pragma weak pthread_setspecific
40 #pragma weak pthread_getspecific
41 #pragma weak pthread_once
42 #ifdef LIBCXXRT_WEAK_LOCKS
43 #pragma weak pthread_mutex_lock
44 #define pthread_mutex_lock(mtx) do {\
45 if (pthread_mutex_lock) pthread_mutex_lock(mtx);\
47 #pragma weak pthread_mutex_unlock
48 #define pthread_mutex_unlock(mtx) do {\
49 if (pthread_mutex_unlock) pthread_mutex_unlock(mtx);\
51 #pragma weak pthread_cond_signal
52 #define pthread_cond_signal(cv) do {\
53 if (pthread_cond_signal) pthread_cond_signal(cv);\
55 #pragma weak pthread_cond_wait
56 #define pthread_cond_wait(cv, mtx) do {\
57 if (pthread_cond_wait) pthread_cond_wait(cv, mtx);\
61 using namespace ABI_NAMESPACE;
64 * Saves the result of the landing pad that we have found. For ARM, this is
65 * stored in the generic unwind structure, while on other platforms it is
66 * stored in the C++ exception.
68 static void saveLandingPad(struct _Unwind_Context *context,
69 struct _Unwind_Exception *ucb,
70 struct __cxa_exception *ex,
72 dw_eh_ptr_t landingPad)
74 #if defined(__arm__) && !defined(__ARM_DWARF_EH__)
75 // On ARM, we store the saved exception in the generic part of the structure
76 ucb->barrier_cache.sp = _Unwind_GetGR(context, 13);
77 ucb->barrier_cache.bitpattern[1] = static_cast<uint32_t>(selector);
78 ucb->barrier_cache.bitpattern[3] = reinterpret_cast<uint32_t>(landingPad);
80 // Cache the results for the phase 2 unwind, if we found a handler
81 // and this is not a foreign exception.
84 ex->handlerSwitchValue = selector;
85 ex->catchTemp = landingPad;
90 * Loads the saved landing pad. Returns 1 on success, 0 on failure.
92 static int loadLandingPad(struct _Unwind_Context *context,
93 struct _Unwind_Exception *ucb,
94 struct __cxa_exception *ex,
95 unsigned long *selector,
96 dw_eh_ptr_t *landingPad)
98 #if defined(__arm__) && !defined(__ARM_DWARF_EH__)
99 *selector = ucb->barrier_cache.bitpattern[1];
100 *landingPad = reinterpret_cast<dw_eh_ptr_t>(ucb->barrier_cache.bitpattern[3]);
105 *selector = ex->handlerSwitchValue;
106 *landingPad = reinterpret_cast<dw_eh_ptr_t>(ex->catchTemp);
113 static inline _Unwind_Reason_Code continueUnwinding(struct _Unwind_Exception *ex,
114 struct _Unwind_Context *context)
116 #if defined(__arm__) && !defined(__ARM_DWARF_EH__)
117 if (__gnu_unwind_frame(ex, context) != _URC_OK) { return _URC_FAILURE; }
119 return _URC_CONTINUE_UNWIND;
123 extern "C" void __cxa_free_exception(void *thrown_exception);
124 extern "C" void __cxa_free_dependent_exception(void *thrown_exception);
125 extern "C" void* __dynamic_cast(const void *sub,
126 const __class_type_info *src,
127 const __class_type_info *dst,
128 ptrdiff_t src2dst_offset);
131 * The type of a handler that has been found.
138 * A cleanup - the exception will propagate through this frame, but code
139 * must be run when this happens.
143 * A catch statement. The exception will not propagate past this frame
144 * (without an explicit rethrow).
150 * Per-thread info required by the runtime. We store a single structure
151 * pointer in thread-local storage, because this tends to be a scarce resource
152 * and it's impolite to steal all of it and not leave any for the rest of the
155 * Instances of this structure are allocated lazily - at most one per thread -
156 * and are destroyed on thread termination.
158 struct __cxa_thread_info
160 /** The termination handler for this thread. */
161 terminate_handler terminateHandler;
162 /** The unexpected exception handler for this thread. */
163 unexpected_handler unexpectedHandler;
165 * The number of emergency buffers held by this thread. This is 0 in
166 * normal operation - the emergency buffers are only used when malloc()
167 * fails to return memory for allocating an exception. Threads are not
168 * permitted to hold more than 4 emergency buffers (as per recommendation
169 * in ABI spec [3.3.1]).
171 int emergencyBuffersHeld;
173 * The exception currently running in a cleanup.
175 _Unwind_Exception *currentCleanup;
177 * Our state with respect to foreign exceptions. Usually none, set to
178 * caught if we have just caught an exception and rethrown if we are
186 } foreign_exception_state;
188 * The public part of this structure, accessible from outside of this
191 __cxa_eh_globals globals;
194 * Dependent exception. This
196 struct __cxa_dependent_exception
199 void *primaryException;
201 std::type_info *exceptionType;
202 void (*exceptionDestructor) (void *);
203 unexpected_handler unexpectedHandler;
204 terminate_handler terminateHandler;
205 __cxa_exception *nextException;
207 #if defined(__arm__) && !defined(__ARM_DWARF_EH__)
208 _Unwind_Exception *nextCleanup;
211 int handlerSwitchValue;
212 const char *actionRecord;
213 const char *languageSpecificData;
217 void *primaryException;
219 _Unwind_Exception unwindHeader;
229 virtual ~exception() throw();
230 virtual const char* what() const throw();
236 * Class of exceptions to distinguish between this and other exception types.
238 * The first four characters are the vendor ID. Currently, we use GNUC,
239 * because we aim for ABI-compatibility with the GNU implementation, and
240 * various checks may test for equality of the class, which is incorrect.
242 static const uint64_t exception_class =
243 EXCEPTION_CLASS('G', 'N', 'U', 'C', 'C', '+', '+', '\0');
245 * Class used for dependent exceptions.
247 static const uint64_t dependent_exception_class =
248 EXCEPTION_CLASS('G', 'N', 'U', 'C', 'C', '+', '+', '\x01');
250 * The low four bytes of the exception class, indicating that we conform to the
251 * Itanium C++ ABI. This is currently unused, but should be used in the future
252 * if we change our exception class, to allow this library and libsupc++ to be
253 * linked to the same executable and both to interoperate.
255 static const uint32_t abi_exception_class =
256 GENERIC_EXCEPTION_CLASS('C', '+', '+', '\0');
258 static bool isCXXException(uint64_t cls)
260 return (cls == exception_class) || (cls == dependent_exception_class);
263 static bool isDependentException(uint64_t cls)
265 return cls == dependent_exception_class;
268 static __cxa_exception *exceptionFromPointer(void *ex)
270 return reinterpret_cast<__cxa_exception*>(static_cast<char*>(ex) -
271 offsetof(struct __cxa_exception, unwindHeader));
273 static __cxa_exception *realExceptionFromException(__cxa_exception *ex)
275 if (!isDependentException(ex->unwindHeader.exception_class)) { return ex; }
276 return reinterpret_cast<__cxa_exception*>((reinterpret_cast<__cxa_dependent_exception*>(ex))->primaryException)-1;
282 // Forward declaration of standard library terminate() function used to
284 void terminate(void);
287 using namespace ABI_NAMESPACE;
291 /** The global termination handler. */
292 static terminate_handler terminateHandler = abort;
293 /** The global unexpected exception handler. */
294 static unexpected_handler unexpectedHandler = std::terminate;
296 /** Key used for thread-local data. */
297 static pthread_key_t eh_key;
301 * Cleanup function, allowing foreign exception handlers to correctly destroy
302 * this exception if they catch it.
304 static void exception_cleanup(_Unwind_Reason_Code reason,
305 struct _Unwind_Exception *ex)
308 // [__cxa_exception [_Unwind_Exception]] [exception object]
310 // __cxa_free_exception expects a pointer to the exception object
311 __cxa_free_exception(static_cast<void*>(ex + 1));
313 static void dependent_exception_cleanup(_Unwind_Reason_Code reason,
314 struct _Unwind_Exception *ex)
317 __cxa_free_dependent_exception(static_cast<void*>(ex + 1));
321 * Recursively walk a list of exceptions and delete them all in post-order.
323 static void free_exception_list(__cxa_exception *ex)
325 if (0 != ex->nextException)
327 free_exception_list(ex->nextException);
329 // __cxa_free_exception() expects to be passed the thrown object, which
330 // immediately follows the exception, not the exception itself
331 __cxa_free_exception(ex+1);
335 * Cleanup function called when a thread exists to make certain that all of the
336 * per-thread data is deleted.
338 static void thread_cleanup(void* thread_info)
340 __cxa_thread_info *info = static_cast<__cxa_thread_info*>(thread_info);
341 if (info->globals.caughtExceptions)
343 // If this is a foreign exception, ask it to clean itself up.
344 if (info->foreign_exception_state != __cxa_thread_info::none)
346 _Unwind_Exception *e = reinterpret_cast<_Unwind_Exception*>(info->globals.caughtExceptions);
347 if (e->exception_cleanup)
348 e->exception_cleanup(_URC_FOREIGN_EXCEPTION_CAUGHT, e);
352 free_exception_list(info->globals.caughtExceptions);
360 * Once control used to protect the key creation.
362 static pthread_once_t once_control = PTHREAD_ONCE_INIT;
365 * We may not be linked against a full pthread implementation. If we're not,
366 * then we need to fake the thread-local storage by storing 'thread-local'
367 * things in a global.
371 * Thread-local storage for a single-threaded program.
373 static __cxa_thread_info singleThreadInfo;
377 static void init_key(void)
379 if ((0 == pthread_key_create) ||
380 (0 == pthread_setspecific) ||
381 (0 == pthread_getspecific))
386 pthread_key_create(&eh_key, thread_cleanup);
387 pthread_setspecific(eh_key, reinterpret_cast<void *>(0x42));
388 fakeTLS = (pthread_getspecific(eh_key) != reinterpret_cast<void *>(0x42));
389 pthread_setspecific(eh_key, 0);
393 * Returns the thread info structure, creating it if it is not already created.
395 static __cxa_thread_info *thread_info()
397 if ((0 == pthread_once) || pthread_once(&once_control, init_key))
401 if (fakeTLS) { return &singleThreadInfo; }
402 __cxa_thread_info *info = static_cast<__cxa_thread_info*>(pthread_getspecific(eh_key));
405 info = static_cast<__cxa_thread_info*>(calloc(1, sizeof(__cxa_thread_info)));
406 pthread_setspecific(eh_key, info);
411 * Fast version of thread_info(). May fail if thread_info() is not called on
412 * this thread at least once already.
414 static __cxa_thread_info *thread_info_fast()
416 if (fakeTLS) { return &singleThreadInfo; }
417 return static_cast<__cxa_thread_info*>(pthread_getspecific(eh_key));
420 * ABI function returning the __cxa_eh_globals structure.
422 extern "C" __cxa_eh_globals *ABI_NAMESPACE::__cxa_get_globals(void)
424 return &(thread_info()->globals);
427 * Version of __cxa_get_globals() assuming that __cxa_get_globals() has already
428 * been called at least once by this thread.
430 extern "C" __cxa_eh_globals *ABI_NAMESPACE::__cxa_get_globals_fast(void)
432 return &(thread_info_fast()->globals);
436 * An emergency allocation reserved for when malloc fails. This is treated as
437 * 16 buffers of 1KB each.
439 static char emergency_buffer[16384];
441 * Flag indicating whether each buffer is allocated.
443 static bool buffer_allocated[16];
445 * Lock used to protect emergency allocation.
447 static pthread_mutex_t emergency_malloc_lock = PTHREAD_MUTEX_INITIALIZER;
449 * Condition variable used to wait when two threads are both trying to use the
450 * emergency malloc() buffer at once.
452 static pthread_cond_t emergency_malloc_wait = PTHREAD_COND_INITIALIZER;
455 * Allocates size bytes from the emergency allocation mechanism, if possible.
456 * This function will fail if size is over 1KB or if this thread already has 4
457 * emergency buffers. If all emergency buffers are allocated, it will sleep
458 * until one becomes available.
460 static char *emergency_malloc(size_t size)
462 if (size > 1024) { return 0; }
464 __cxa_thread_info *info = thread_info();
465 // Only 4 emergency buffers allowed per thread!
466 if (info->emergencyBuffersHeld > 3) { return 0; }
468 pthread_mutex_lock(&emergency_malloc_lock);
472 // While we were sleeping on the lock, another thread might have free'd
473 // enough memory for us to use, so try the allocation again - no point
474 // using the emergency buffer if there is some real memory that we can
476 void *m = calloc(1, size);
479 pthread_mutex_unlock(&emergency_malloc_lock);
480 return static_cast<char*>(m);
482 for (int i=0 ; i<16 ; i++)
484 if (!buffer_allocated[i])
487 buffer_allocated[i] = true;
491 // If there still isn't a buffer available, then sleep on the condition
492 // variable. This will be signalled when another thread releases one
493 // of the emergency buffers.
496 pthread_cond_wait(&emergency_malloc_wait, &emergency_malloc_lock);
499 pthread_mutex_unlock(&emergency_malloc_lock);
500 info->emergencyBuffersHeld++;
501 return emergency_buffer + (1024 * buffer);
505 * Frees a buffer returned by emergency_malloc().
507 * Note: Neither this nor emergency_malloc() is particularly efficient. This
508 * should not matter, because neither will be called in normal operation - they
509 * are only used when the program runs out of memory, which should not happen
512 static void emergency_malloc_free(char *ptr)
515 // Find the buffer corresponding to this pointer.
516 for (int i=0 ; i<16 ; i++)
518 if (ptr == static_cast<void*>(emergency_buffer + (1024 * i)))
524 assert(buffer >= 0 &&
525 "Trying to free something that is not an emergency buffer!");
526 // emergency_malloc() is expected to return 0-initialized data. We don't
527 // zero the buffer when allocating it, because the static buffers will
528 // begin life containing 0 values.
529 memset(ptr, 0, 1024);
530 // Signal the condition variable to wake up any threads that are blocking
531 // waiting for some space in the emergency buffer
532 pthread_mutex_lock(&emergency_malloc_lock);
533 // In theory, we don't need to do this with the lock held. In practice,
534 // our array of bools will probably be updated using 32-bit or 64-bit
535 // memory operations, so this update may clobber adjacent values.
536 buffer_allocated[buffer] = false;
537 pthread_cond_signal(&emergency_malloc_wait);
538 pthread_mutex_unlock(&emergency_malloc_lock);
541 static char *alloc_or_die(size_t size)
543 char *buffer = static_cast<char*>(calloc(1, size));
545 // If calloc() doesn't want to give us any memory, try using an emergency
549 buffer = emergency_malloc(size);
550 // This is only reached if the allocation is greater than 1KB, and
551 // anyone throwing objects that big really should know better.
554 fprintf(stderr, "Out of memory attempting to allocate exception\n");
560 static void free_exception(char *e)
562 // If this allocation is within the address range of the emergency buffer,
563 // don't call free() because it was not allocated with malloc()
564 if ((e >= emergency_buffer) &&
565 (e < (emergency_buffer + sizeof(emergency_buffer))))
567 emergency_malloc_free(e);
576 * Allocates an exception structure. Returns a pointer to the space that can
577 * be used to store an object of thrown_size bytes. This function will use an
578 * emergency buffer if malloc() fails, and may block if there are no such
581 extern "C" void *__cxa_allocate_exception(size_t thrown_size)
583 size_t size = thrown_size + sizeof(__cxa_exception);
584 char *buffer = alloc_or_die(size);
585 return buffer+sizeof(__cxa_exception);
588 extern "C" void *__cxa_allocate_dependent_exception(void)
590 size_t size = sizeof(__cxa_dependent_exception);
591 char *buffer = alloc_or_die(size);
592 return buffer+sizeof(__cxa_dependent_exception);
596 * __cxa_free_exception() is called when an exception was thrown in between
597 * calling __cxa_allocate_exception() and actually throwing the exception.
598 * This happens when the object's copy constructor throws an exception.
600 * In this implementation, it is also called by __cxa_end_catch() and during
603 extern "C" void __cxa_free_exception(void *thrown_exception)
605 __cxa_exception *ex = reinterpret_cast<__cxa_exception*>(thrown_exception) - 1;
606 // Free the object that was thrown, calling its destructor
607 if (0 != ex->exceptionDestructor)
611 ex->exceptionDestructor(thrown_exception);
615 // FIXME: Check that this is really what the spec says to do.
620 free_exception(reinterpret_cast<char*>(ex));
623 static void releaseException(__cxa_exception *exception)
625 if (isDependentException(exception->unwindHeader.exception_class))
627 __cxa_free_dependent_exception(exception+1);
630 if (__sync_sub_and_fetch(&exception->referenceCount, 1) == 0)
632 // __cxa_free_exception() expects to be passed the thrown object,
633 // which immediately follows the exception, not the exception
635 __cxa_free_exception(exception+1);
639 void __cxa_free_dependent_exception(void *thrown_exception)
641 __cxa_dependent_exception *ex = reinterpret_cast<__cxa_dependent_exception*>(thrown_exception) - 1;
642 assert(isDependentException(ex->unwindHeader.exception_class));
643 if (ex->primaryException)
645 releaseException(realExceptionFromException(reinterpret_cast<__cxa_exception*>(ex)));
647 free_exception(reinterpret_cast<char*>(ex));
651 * Callback function used with _Unwind_Backtrace().
653 * Prints a stack trace. Used only for debugging help.
655 * Note: As of FreeBSD 8.1, dladd() still doesn't work properly, so this only
656 * correctly prints function names from public, relocatable, symbols.
658 static _Unwind_Reason_Code trace(struct _Unwind_Context *context, void *c)
662 dladdr(reinterpret_cast<void *>(__cxa_current_exception_type), &myinfo);
663 void *ip = reinterpret_cast<void*>(_Unwind_GetIP(context));
665 if (dladdr(ip, &info) != 0)
667 if (mylookup == 0 || strcmp(info.dli_fname, myinfo.dli_fname) != 0)
669 printf("%p:%s() in %s\n", ip, info.dli_sname, info.dli_fname);
672 return _URC_CONTINUE_UNWIND;
676 * Report a failure that occurred when attempting to throw an exception.
678 * If the failure happened by falling off the end of the stack without finding
679 * a handler, prints a back trace before aborting.
681 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 4)
682 extern "C" void *__cxa_begin_catch(void *e) throw();
684 extern "C" void *__cxa_begin_catch(void *e);
686 static void report_failure(_Unwind_Reason_Code err, __cxa_exception *thrown_exception)
691 case _URC_FATAL_PHASE1_ERROR:
692 fprintf(stderr, "Fatal error during phase 1 unwinding\n");
694 #if !defined(__arm__) || defined(__ARM_DWARF_EH__)
695 case _URC_FATAL_PHASE2_ERROR:
696 fprintf(stderr, "Fatal error during phase 2 unwinding\n");
699 case _URC_END_OF_STACK:
700 __cxa_begin_catch (&(thrown_exception->unwindHeader));
702 fprintf(stderr, "Terminating due to uncaught exception %p",
703 static_cast<void*>(thrown_exception));
704 thrown_exception = realExceptionFromException(thrown_exception);
705 static const __class_type_info *e_ti =
706 static_cast<const __class_type_info*>(&typeid(std::exception));
707 const __class_type_info *throw_ti =
708 dynamic_cast<const __class_type_info*>(thrown_exception->exceptionType);
712 static_cast<std::exception*>(e_ti->cast_to(static_cast<void*>(thrown_exception+1),
716 fprintf(stderr, " '%s'", e->what());
720 size_t bufferSize = 128;
721 char *demangled = static_cast<char*>(malloc(bufferSize));
722 const char *mangled = thrown_exception->exceptionType->name();
724 demangled = __cxa_demangle(mangled, demangled, &bufferSize, &status);
725 fprintf(stderr, " of type %s\n",
726 status == 0 ? demangled : mangled);
727 if (status == 0) { free(demangled); }
728 // Print a back trace if no handler is found.
729 // TODO: Make this optional
731 _Unwind_Backtrace(trace, 0);
734 // Just abort. No need to call std::terminate for the second time
741 static void throw_exception(__cxa_exception *ex)
743 __cxa_thread_info *info = thread_info();
744 ex->unexpectedHandler = info->unexpectedHandler;
745 if (0 == ex->unexpectedHandler)
747 ex->unexpectedHandler = unexpectedHandler;
749 ex->terminateHandler = info->terminateHandler;
750 if (0 == ex->terminateHandler)
752 ex->terminateHandler = terminateHandler;
754 info->globals.uncaughtExceptions++;
756 _Unwind_Reason_Code err = _Unwind_RaiseException(&ex->unwindHeader);
757 // The _Unwind_RaiseException() function should not return, it should
758 // unwind the stack past this function. If it does return, then something
760 report_failure(err, ex);
765 * ABI function for throwing an exception. Takes the object to be thrown (the
766 * pointer returned by __cxa_allocate_exception()), the type info for the
767 * pointee, and the destructor (if there is one) as arguments.
769 extern "C" void __cxa_throw(void *thrown_exception,
770 std::type_info *tinfo,
773 __cxa_exception *ex = reinterpret_cast<__cxa_exception*>(thrown_exception) - 1;
775 ex->referenceCount = 1;
776 ex->exceptionType = tinfo;
778 ex->exceptionDestructor = dest;
780 ex->unwindHeader.exception_class = exception_class;
781 ex->unwindHeader.exception_cleanup = exception_cleanup;
786 extern "C" void __cxa_rethrow_primary_exception(void* thrown_exception)
788 if (NULL == thrown_exception) { return; }
790 __cxa_exception *original = exceptionFromPointer(thrown_exception);
791 __cxa_dependent_exception *ex = reinterpret_cast<__cxa_dependent_exception*>(__cxa_allocate_dependent_exception())-1;
793 ex->primaryException = thrown_exception;
794 __cxa_increment_exception_refcount(thrown_exception);
796 ex->exceptionType = original->exceptionType;
797 ex->unwindHeader.exception_class = dependent_exception_class;
798 ex->unwindHeader.exception_cleanup = dependent_exception_cleanup;
800 throw_exception(reinterpret_cast<__cxa_exception*>(ex));
803 extern "C" void *__cxa_current_primary_exception(void)
805 __cxa_eh_globals* globals = __cxa_get_globals();
806 __cxa_exception *ex = globals->caughtExceptions;
808 if (0 == ex) { return NULL; }
809 ex = realExceptionFromException(ex);
810 __sync_fetch_and_add(&ex->referenceCount, 1);
814 extern "C" void __cxa_increment_exception_refcount(void* thrown_exception)
816 if (NULL == thrown_exception) { return; }
817 __cxa_exception *ex = static_cast<__cxa_exception*>(thrown_exception) - 1;
818 if (isDependentException(ex->unwindHeader.exception_class)) { return; }
819 __sync_fetch_and_add(&ex->referenceCount, 1);
821 extern "C" void __cxa_decrement_exception_refcount(void* thrown_exception)
823 if (NULL == thrown_exception) { return; }
824 __cxa_exception *ex = static_cast<__cxa_exception*>(thrown_exception) - 1;
825 releaseException(ex);
829 * ABI function. Rethrows the current exception. Does not remove the
830 * exception from the stack or decrement its handler count - the compiler is
831 * expected to set the landing pad for this function to the end of the catch
832 * block, and then call _Unwind_Resume() to continue unwinding once
833 * __cxa_end_catch() has been called and any cleanup code has been run.
835 extern "C" void __cxa_rethrow()
837 __cxa_thread_info *ti = thread_info();
838 __cxa_eh_globals *globals = &ti->globals;
839 // Note: We don't remove this from the caught list here, because
840 // __cxa_end_catch will be called when we unwind out of the try block. We
841 // could probably make this faster by providing an alternative rethrow
842 // function and ensuring that all cleanup code is run before calling it, so
843 // we can skip the top stack frame when unwinding.
844 __cxa_exception *ex = globals->caughtExceptions;
849 "Attempting to rethrow an exception that doesn't exist!\n");
853 if (ti->foreign_exception_state != __cxa_thread_info::none)
855 ti->foreign_exception_state = __cxa_thread_info::rethrown;
856 _Unwind_Exception *e = reinterpret_cast<_Unwind_Exception*>(ex);
857 _Unwind_Reason_Code err = _Unwind_Resume_or_Rethrow(e);
858 report_failure(err, ex);
862 assert(ex->handlerCount > 0 && "Rethrowing uncaught exception!");
864 // ex->handlerCount will be decremented in __cxa_end_catch in enclosing
867 // Make handler count negative. This will tell __cxa_end_catch that
868 // exception was rethrown and exception object should not be destroyed
869 // when handler count become zero
870 ex->handlerCount = -ex->handlerCount;
872 // Continue unwinding the stack with this exception. This should unwind to
873 // the place in the caller where __cxa_end_catch() is called. The caller
874 // will then run cleanup code and bounce the exception back with
876 _Unwind_Reason_Code err = _Unwind_Resume_or_Rethrow(&ex->unwindHeader);
877 report_failure(err, ex);
881 * Returns the type_info object corresponding to the filter.
883 static std::type_info *get_type_info_entry(_Unwind_Context *context,
887 // Get the address of the record in the table.
888 dw_eh_ptr_t record = lsda->type_table -
889 dwarf_size_of_fixed_size_field(lsda->type_table_encoding)*filter;
891 dw_eh_ptr_t start = record;
892 // Read the value, but it's probably an indirect reference...
893 int64_t offset = read_value(lsda->type_table_encoding, &record);
895 // (If the entry is 0, don't try to dereference it. That would be bad.)
896 if (offset == 0) { return 0; }
898 // ...so we need to resolve it
899 return reinterpret_cast<std::type_info*>(resolve_indirect_value(context,
900 lsda->type_table_encoding, offset, start));
906 * Checks the type signature found in a handler against the type of the thrown
907 * object. If ex is 0 then it is assumed to be a foreign exception and only
910 static bool check_type_signature(__cxa_exception *ex,
911 const std::type_info *type,
914 void *exception_ptr = static_cast<void*>(ex+1);
915 const std::type_info *ex_type = ex ? ex->exceptionType : 0;
917 bool is_ptr = ex ? ex_type->__is_pointer_p() : false;
920 exception_ptr = *static_cast<void**>(exception_ptr);
922 // Always match a catchall, even with a foreign exception
924 // Note: A 0 here is a catchall, not a cleanup, so we return true to
925 // indicate that we found a catch.
930 adjustedPtr = exception_ptr;
935 if (0 == ex) { return false; }
937 // If the types are the same, no casting is needed.
938 if (*type == *ex_type)
940 adjustedPtr = exception_ptr;
945 if (type->__do_catch(ex_type, &exception_ptr, 1))
947 adjustedPtr = exception_ptr;
954 * Checks whether the exception matches the type specifiers in this action
955 * record. If the exception only matches cleanups, then this returns false.
956 * If it matches a catch (including a catchall) then it returns true.
958 * The selector argument is used to return the selector that is passed in the
959 * second exception register when installing the context.
961 static handler_type check_action_record(_Unwind_Context *context,
963 dw_eh_ptr_t action_record,
965 unsigned long *selector,
968 if (!action_record) { return handler_cleanup; }
969 handler_type found = handler_none;
970 while (action_record)
972 int filter = read_sleb128(&action_record);
973 dw_eh_ptr_t action_record_offset_base = action_record;
974 int displacement = read_sleb128(&action_record);
975 action_record = displacement ?
976 action_record_offset_base + displacement : 0;
977 // We only check handler types for C++ exceptions - foreign exceptions
978 // are only allowed for cleanups and catchalls.
981 std::type_info *handler_type = get_type_info_entry(context, lsda, filter);
982 if (check_type_signature(ex, handler_type, adjustedPtr))
985 return handler_catch;
988 else if (filter < 0 && 0 != ex)
990 bool matched = false;
992 #if defined(__arm__) && !defined(__ARM_DWARF_EH__)
994 std::type_info *handler_type = get_type_info_entry(context, lsda, filter--);
997 if (check_type_signature(ex, handler_type, adjustedPtr))
1002 handler_type = get_type_info_entry(context, lsda, filter--);
1005 unsigned char *type_index = reinterpret_cast<unsigned char*>(lsda->type_table) - filter - 1;
1008 std::type_info *handler_type = get_type_info_entry(context, lsda, *(type_index++));
1009 // If the exception spec matches a permitted throw type for
1010 // this function, don't report a handler - we are allowed to
1011 // propagate this exception out.
1012 if (check_type_signature(ex, handler_type, adjustedPtr))
1019 if (matched) { continue; }
1020 // If we don't find an allowed exception spec, we need to install
1021 // the context for this action. The landing pad will then call the
1022 // unexpected exception function. Treat this as a catch
1023 return handler_catch;
1025 else if (filter == 0)
1028 found = handler_cleanup;
1034 static void pushCleanupException(_Unwind_Exception *exceptionObject,
1035 __cxa_exception *ex)
1037 #if defined(__arm__) && !defined(__ARM_DWARF_EH__)
1038 __cxa_thread_info *info = thread_info_fast();
1042 if (ex->cleanupCount > 1)
1044 assert(exceptionObject == info->currentCleanup);
1047 ex->nextCleanup = info->currentCleanup;
1049 info->currentCleanup = exceptionObject;
1054 * The exception personality function. This is referenced in the unwinding
1055 * DWARF metadata and is called by the unwind library for each C++ stack frame
1056 * containing catch or cleanup code.
1059 BEGIN_PERSONALITY_FUNCTION(__gxx_personality_v0)
1060 // This personality function is for version 1 of the ABI. If you use it
1061 // with a future version of the ABI, it won't know what to do, so it
1062 // reports a fatal error and give up before it breaks anything.
1065 return _URC_FATAL_PHASE1_ERROR;
1067 __cxa_exception *ex = 0;
1068 __cxa_exception *realEx = 0;
1070 // If this exception is throw by something else then we can't make any
1071 // assumptions about its layout beyond the fields declared in
1072 // _Unwind_Exception.
1073 bool foreignException = !isCXXException(exceptionClass);
1075 // If this isn't a foreign exception, then we have a C++ exception structure
1076 if (!foreignException)
1078 ex = exceptionFromPointer(exceptionObject);
1079 realEx = realExceptionFromException(ex);
1082 #if defined(__arm__) && !defined(__ARM_DWARF_EH__)
1083 unsigned char *lsda_addr =
1084 static_cast<unsigned char*>(_Unwind_GetLanguageSpecificData(context));
1086 unsigned char *lsda_addr =
1087 reinterpret_cast<unsigned char*>(static_cast<uintptr_t>(_Unwind_GetLanguageSpecificData(context)));
1090 // No LSDA implies no landing pads - try the next frame
1091 if (0 == lsda_addr) { return continueUnwinding(exceptionObject, context); }
1093 // These two variables define how the exception will be handled.
1094 dwarf_eh_action action = {0};
1095 unsigned long selector = 0;
1097 // During the search phase, we do a complete lookup. If we return
1098 // _URC_HANDLER_FOUND, then the phase 2 unwind will call this function with
1099 // a _UA_HANDLER_FRAME action, telling us to install the handler frame. If
1100 // we return _URC_CONTINUE_UNWIND, we may be called again later with a
1101 // _UA_CLEANUP_PHASE action for this frame.
1103 // The point of the two-stage unwind allows us to entirely avoid any stack
1104 // unwinding if there is no handler. If there are just cleanups found,
1105 // then we can just panic call an abort function.
1107 // Matching a handler is much more expensive than matching a cleanup,
1108 // because we don't need to bother doing type comparisons (or looking at
1109 // the type table at all) for a cleanup. This means that there is no need
1110 // to cache the result of finding a cleanup, because it's (quite) quick to
1111 // look it up again from the action table.
1112 if (actions & _UA_SEARCH_PHASE)
1114 struct dwarf_eh_lsda lsda = parse_lsda(context, lsda_addr);
1116 if (!dwarf_eh_find_callsite(context, &lsda, &action))
1118 // EH range not found. This happens if exception is thrown and not
1119 // caught inside a cleanup (destructor). We should call
1120 // terminate() in this case. The catchTemp (landing pad) field of
1121 // exception object will contain null when personality function is
1122 // called with _UA_HANDLER_FRAME action for phase 2 unwinding.
1123 return _URC_HANDLER_FOUND;
1126 handler_type found_handler = check_action_record(context, &lsda,
1127 action.action_record, realEx, &selector, ex->adjustedPtr);
1128 // If there's no action record, we've only found a cleanup, so keep
1129 // searching for something real
1130 if (found_handler == handler_catch)
1132 // Cache the results for the phase 2 unwind, if we found a handler
1133 // and this is not a foreign exception.
1136 saveLandingPad(context, exceptionObject, ex, selector, action.landing_pad);
1137 ex->languageSpecificData = reinterpret_cast<const char*>(lsda_addr);
1138 ex->actionRecord = reinterpret_cast<const char*>(action.action_record);
1139 // ex->adjustedPtr is set when finding the action record.
1141 return _URC_HANDLER_FOUND;
1143 return continueUnwinding(exceptionObject, context);
1147 // If this is a foreign exception, we didn't have anywhere to cache the
1148 // lookup stuff, so we need to do it again. If this is either a forced
1149 // unwind, a foreign exception, or a cleanup, then we just install the
1150 // context for a cleanup.
1151 if (!(actions & _UA_HANDLER_FRAME))
1154 struct dwarf_eh_lsda lsda = parse_lsda(context, lsda_addr);
1155 dwarf_eh_find_callsite(context, &lsda, &action);
1156 if (0 == action.landing_pad) { return continueUnwinding(exceptionObject, context); }
1157 handler_type found_handler = check_action_record(context, &lsda,
1158 action.action_record, realEx, &selector, ex->adjustedPtr);
1159 // Ignore handlers this time.
1160 if (found_handler != handler_cleanup) { return continueUnwinding(exceptionObject, context); }
1161 pushCleanupException(exceptionObject, ex);
1163 else if (foreignException)
1165 struct dwarf_eh_lsda lsda = parse_lsda(context, lsda_addr);
1166 dwarf_eh_find_callsite(context, &lsda, &action);
1167 check_action_record(context, &lsda, action.action_record, realEx,
1168 &selector, ex->adjustedPtr);
1170 else if (ex->catchTemp == 0)
1172 // Uncaught exception in cleanup, calling terminate
1177 // Restore the saved info if we saved some last time.
1178 loadLandingPad(context, exceptionObject, ex, &selector, &action.landing_pad);
1180 ex->handlerSwitchValue = 0;
1184 _Unwind_SetIP(context, reinterpret_cast<unsigned long>(action.landing_pad));
1185 _Unwind_SetGR(context, __builtin_eh_return_data_regno(0),
1186 reinterpret_cast<unsigned long>(exceptionObject));
1187 _Unwind_SetGR(context, __builtin_eh_return_data_regno(1), selector);
1189 return _URC_INSTALL_CONTEXT;
1193 * ABI function called when entering a catch statement. The argument is the
1194 * pointer passed out of the personality function. This is always the start of
1195 * the _Unwind_Exception object. The return value for this function is the
1196 * pointer to the caught exception, which is either the adjusted pointer (for
1197 * C++ exceptions) of the unadjusted pointer (for foreign exceptions).
1199 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 4)
1200 extern "C" void *__cxa_begin_catch(void *e) throw()
1202 extern "C" void *__cxa_begin_catch(void *e)
1205 // We can't call the fast version here, because if the first exception that
1206 // we see is a foreign exception then we won't have called it yet.
1207 __cxa_thread_info *ti = thread_info();
1208 __cxa_eh_globals *globals = &ti->globals;
1209 globals->uncaughtExceptions--;
1210 _Unwind_Exception *exceptionObject = static_cast<_Unwind_Exception*>(e);
1212 if (isCXXException(exceptionObject->exception_class))
1214 __cxa_exception *ex = exceptionFromPointer(exceptionObject);
1216 if (ex->handlerCount == 0)
1218 // Add this to the front of the list of exceptions being handled
1219 // and increment its handler count so that it won't be deleted
1221 ex->nextException = globals->caughtExceptions;
1222 globals->caughtExceptions = ex;
1225 if (ex->handlerCount < 0)
1227 // Rethrown exception is catched before end of catch block.
1228 // Clear the rethrow flag (make value positive) - we are allowed
1229 // to delete this exception at the end of the catch block, as long
1230 // as it isn't thrown again later.
1242 // __cxa_begin_catch() <- we are here
1245 ex->handlerCount = -ex->handlerCount + 1;
1251 ti->foreign_exception_state = __cxa_thread_info::none;
1253 return ex->adjustedPtr;
1257 // If this is a foreign exception, then we need to be able to
1258 // store it. We can't chain foreign exceptions, so we give up
1259 // if there are already some outstanding ones.
1260 if (globals->caughtExceptions != 0)
1264 globals->caughtExceptions = reinterpret_cast<__cxa_exception*>(exceptionObject);
1265 ti->foreign_exception_state = __cxa_thread_info::caught;
1267 // exceptionObject is the pointer to the _Unwind_Exception within the
1268 // __cxa_exception. The throw object is after this
1269 return (reinterpret_cast<char*>(exceptionObject) + sizeof(_Unwind_Exception));
1275 * ABI function called when exiting a catch block. This will free the current
1276 * exception if it is no longer referenced in other catch blocks.
1278 extern "C" void __cxa_end_catch()
1280 // We can call the fast version here because the slow version is called in
1281 // __cxa_throw(), which must have been called before we end a catch block
1282 __cxa_thread_info *ti = thread_info_fast();
1283 __cxa_eh_globals *globals = &ti->globals;
1284 __cxa_exception *ex = globals->caughtExceptions;
1286 assert(0 != ex && "Ending catch when no exception is on the stack!");
1288 if (ti->foreign_exception_state != __cxa_thread_info::none)
1290 if (ti->foreign_exception_state != __cxa_thread_info::rethrown)
1292 _Unwind_Exception *e = reinterpret_cast<_Unwind_Exception*>(ti->globals.caughtExceptions);
1293 if (e->exception_cleanup)
1294 e->exception_cleanup(_URC_FOREIGN_EXCEPTION_CAUGHT, e);
1296 globals->caughtExceptions = 0;
1297 ti->foreign_exception_state = __cxa_thread_info::none;
1301 bool deleteException = true;
1303 if (ex->handlerCount < 0)
1305 // exception was rethrown. Exception should not be deleted even if
1306 // handlerCount become zero.
1316 // __cxa_end_catch(); <- we are here
1322 deleteException = false;
1329 if (ex->handlerCount == 0)
1331 globals->caughtExceptions = ex->nextException;
1332 if (deleteException)
1334 releaseException(ex);
1340 * ABI function. Returns the type of the current exception.
1342 extern "C" std::type_info *__cxa_current_exception_type()
1344 __cxa_eh_globals *globals = __cxa_get_globals();
1345 __cxa_exception *ex = globals->caughtExceptions;
1346 return ex ? ex->exceptionType : 0;
1350 * ABI function, called when an exception specification is violated.
1352 * This function does not return.
1354 extern "C" void __cxa_call_unexpected(void*exception)
1356 _Unwind_Exception *exceptionObject = static_cast<_Unwind_Exception*>(exception);
1357 if (exceptionObject->exception_class == exception_class)
1359 __cxa_exception *ex = exceptionFromPointer(exceptionObject);
1360 if (ex->unexpectedHandler)
1362 ex->unexpectedHandler();
1363 // Should not be reached.
1368 // Should not be reached.
1373 * ABI function, returns the adjusted pointer to the exception object.
1375 extern "C" void *__cxa_get_exception_ptr(void *exceptionObject)
1377 return exceptionFromPointer(exceptionObject)->adjustedPtr;
1381 * As an extension, we provide the ability for the unexpected and terminate
1382 * handlers to be thread-local. We default to the standards-compliant
1383 * behaviour where they are global.
1385 static bool thread_local_handlers = false;
1391 * Sets whether unexpected and terminate handlers should be thread-local.
1393 void set_use_thread_local_handlers(bool flag) throw()
1395 thread_local_handlers = flag;
1398 * Sets a thread-local unexpected handler.
1400 unexpected_handler set_unexpected(unexpected_handler f) throw()
1402 static __cxa_thread_info *info = thread_info();
1403 unexpected_handler old = info->unexpectedHandler;
1404 info->unexpectedHandler = f;
1408 * Sets a thread-local terminate handler.
1410 terminate_handler set_terminate(terminate_handler f) throw()
1412 static __cxa_thread_info *info = thread_info();
1413 terminate_handler old = info->terminateHandler;
1414 info->terminateHandler = f;
1422 * Sets the function that will be called when an exception specification is
1425 unexpected_handler set_unexpected(unexpected_handler f) throw()
1427 if (thread_local_handlers) { return pathscale::set_unexpected(f); }
1429 return ATOMIC_SWAP(&unexpectedHandler, f);
1432 * Sets the function that is called to terminate the program.
1434 terminate_handler set_terminate(terminate_handler f) throw()
1436 if (thread_local_handlers) { return pathscale::set_terminate(f); }
1438 return ATOMIC_SWAP(&terminateHandler, f);
1441 * Terminates the program, calling a custom terminate implementation if
1446 static __cxa_thread_info *info = thread_info();
1447 if (0 != info && 0 != info->terminateHandler)
1449 info->terminateHandler();
1450 // Should not be reached - a terminate handler is not expected to
1457 * Called when an unexpected exception is encountered (i.e. an exception
1458 * violates an exception specification). This calls abort() unless a
1459 * custom handler has been set..
1463 static __cxa_thread_info *info = thread_info();
1464 if (0 != info && 0 != info->unexpectedHandler)
1466 info->unexpectedHandler();
1467 // Should not be reached - a terminate handler is not expected to
1471 unexpectedHandler();
1474 * Returns whether there are any exceptions currently being thrown that
1475 * have not been caught. This can occur inside a nested catch statement.
1477 bool uncaught_exception() throw()
1479 __cxa_thread_info *info = thread_info();
1480 return info->globals.uncaughtExceptions != 0;
1483 * Returns the number of exceptions currently being thrown that have not
1484 * been caught. This can occur inside a nested catch statement.
1486 int uncaught_exceptions() throw()
1488 __cxa_thread_info *info = thread_info();
1489 return info->globals.uncaughtExceptions;
1492 * Returns the current unexpected handler.
1494 unexpected_handler get_unexpected() throw()
1496 __cxa_thread_info *info = thread_info();
1497 if (info->unexpectedHandler)
1499 return info->unexpectedHandler;
1501 return ATOMIC_LOAD(&unexpectedHandler);
1504 * Returns the current terminate handler.
1506 terminate_handler get_terminate() throw()
1508 __cxa_thread_info *info = thread_info();
1509 if (info->terminateHandler)
1511 return info->terminateHandler;
1513 return ATOMIC_LOAD(&terminateHandler);
1516 #if defined(__arm__) && !defined(__ARM_DWARF_EH__)
1517 extern "C" _Unwind_Exception *__cxa_get_cleanup(void)
1519 __cxa_thread_info *info = thread_info_fast();
1520 _Unwind_Exception *exceptionObject = info->currentCleanup;
1521 if (isCXXException(exceptionObject->exception_class))
1523 __cxa_exception *ex = exceptionFromPointer(exceptionObject);
1525 if (ex->cleanupCount == 0)
1527 info->currentCleanup = ex->nextCleanup;
1528 ex->nextCleanup = 0;
1533 info->currentCleanup = 0;
1535 return exceptionObject;
1539 ".pushsection .text.__cxa_end_cleanup \n"
1540 ".global __cxa_end_cleanup \n"
1541 ".type __cxa_end_cleanup, \"function\" \n"
1542 "__cxa_end_cleanup: \n"
1543 " push {r1, r2, r3, r4} \n"
1544 " bl __cxa_get_cleanup \n"
1545 " push {r1, r2, r3, r4} \n"
1546 " b _Unwind_Resume \n"