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);
577 * There's an ABI bug in __cxa_exception: unwindHeader requires 16-byte
578 * alignment but it was broken by the addition of the referenceCount.
579 * The unwindHeader is at offset 0x58 in __cxa_exception. In order to keep
580 * compatibility with consumers of the broken __cxa_exception, explicitly add
581 * padding on allocation (and account for it on free).
583 static const int exception_alignment_padding = 8;
585 static const int exception_alignment_padding = 0;
589 * Allocates an exception structure. Returns a pointer to the space that can
590 * be used to store an object of thrown_size bytes. This function will use an
591 * emergency buffer if malloc() fails, and may block if there are no such
594 extern "C" void *__cxa_allocate_exception(size_t thrown_size)
596 size_t size = exception_alignment_padding + sizeof(__cxa_exception) +
598 char *buffer = alloc_or_die(size);
599 return buffer + exception_alignment_padding + sizeof(__cxa_exception);
602 extern "C" void *__cxa_allocate_dependent_exception(void)
604 size_t size = exception_alignment_padding +
605 sizeof(__cxa_dependent_exception);
606 char *buffer = alloc_or_die(size);
607 return buffer + exception_alignment_padding +
608 sizeof(__cxa_dependent_exception);
612 * __cxa_free_exception() is called when an exception was thrown in between
613 * calling __cxa_allocate_exception() and actually throwing the exception.
614 * This happens when the object's copy constructor throws an exception.
616 * In this implementation, it is also called by __cxa_end_catch() and during
619 extern "C" void __cxa_free_exception(void *thrown_exception)
621 __cxa_exception *ex = reinterpret_cast<__cxa_exception*>(thrown_exception) - 1;
622 // Free the object that was thrown, calling its destructor
623 if (0 != ex->exceptionDestructor)
627 ex->exceptionDestructor(thrown_exception);
631 // FIXME: Check that this is really what the spec says to do.
636 free_exception(reinterpret_cast<char*>(ex) -
637 exception_alignment_padding);
640 static void releaseException(__cxa_exception *exception)
642 if (isDependentException(exception->unwindHeader.exception_class))
644 __cxa_free_dependent_exception(exception+1);
647 if (__sync_sub_and_fetch(&exception->referenceCount, 1) == 0)
649 // __cxa_free_exception() expects to be passed the thrown object,
650 // which immediately follows the exception, not the exception
652 __cxa_free_exception(exception+1);
656 void __cxa_free_dependent_exception(void *thrown_exception)
658 __cxa_dependent_exception *ex = reinterpret_cast<__cxa_dependent_exception*>(thrown_exception) - 1;
659 assert(isDependentException(ex->unwindHeader.exception_class));
660 if (ex->primaryException)
662 releaseException(realExceptionFromException(reinterpret_cast<__cxa_exception*>(ex)));
664 free_exception(reinterpret_cast<char*>(ex) -
665 exception_alignment_padding);
669 * Callback function used with _Unwind_Backtrace().
671 * Prints a stack trace. Used only for debugging help.
673 * Note: As of FreeBSD 8.1, dladd() still doesn't work properly, so this only
674 * correctly prints function names from public, relocatable, symbols.
676 static _Unwind_Reason_Code trace(struct _Unwind_Context *context, void *c)
680 dladdr(reinterpret_cast<void *>(__cxa_current_exception_type), &myinfo);
681 void *ip = reinterpret_cast<void*>(_Unwind_GetIP(context));
683 if (dladdr(ip, &info) != 0)
685 if (mylookup == 0 || strcmp(info.dli_fname, myinfo.dli_fname) != 0)
687 printf("%p:%s() in %s\n", ip, info.dli_sname, info.dli_fname);
690 return _URC_CONTINUE_UNWIND;
694 * Report a failure that occurred when attempting to throw an exception.
696 * If the failure happened by falling off the end of the stack without finding
697 * a handler, prints a back trace before aborting.
699 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 4)
700 extern "C" void *__cxa_begin_catch(void *e) throw();
702 extern "C" void *__cxa_begin_catch(void *e);
704 static void report_failure(_Unwind_Reason_Code err, __cxa_exception *thrown_exception)
709 case _URC_FATAL_PHASE1_ERROR:
710 fprintf(stderr, "Fatal error during phase 1 unwinding\n");
712 #if !defined(__arm__) || defined(__ARM_DWARF_EH__)
713 case _URC_FATAL_PHASE2_ERROR:
714 fprintf(stderr, "Fatal error during phase 2 unwinding\n");
717 case _URC_END_OF_STACK:
718 __cxa_begin_catch (&(thrown_exception->unwindHeader));
720 fprintf(stderr, "Terminating due to uncaught exception %p",
721 static_cast<void*>(thrown_exception));
722 thrown_exception = realExceptionFromException(thrown_exception);
723 static const __class_type_info *e_ti =
724 static_cast<const __class_type_info*>(&typeid(std::exception));
725 const __class_type_info *throw_ti =
726 dynamic_cast<const __class_type_info*>(thrown_exception->exceptionType);
730 static_cast<std::exception*>(e_ti->cast_to(static_cast<void*>(thrown_exception+1),
734 fprintf(stderr, " '%s'", e->what());
738 size_t bufferSize = 128;
739 char *demangled = static_cast<char*>(malloc(bufferSize));
740 const char *mangled = thrown_exception->exceptionType->name();
742 demangled = __cxa_demangle(mangled, demangled, &bufferSize, &status);
743 fprintf(stderr, " of type %s\n",
744 status == 0 ? demangled : mangled);
745 if (status == 0) { free(demangled); }
746 // Print a back trace if no handler is found.
747 // TODO: Make this optional
749 _Unwind_Backtrace(trace, 0);
752 // Just abort. No need to call std::terminate for the second time
759 static void throw_exception(__cxa_exception *ex)
761 __cxa_thread_info *info = thread_info();
762 ex->unexpectedHandler = info->unexpectedHandler;
763 if (0 == ex->unexpectedHandler)
765 ex->unexpectedHandler = unexpectedHandler;
767 ex->terminateHandler = info->terminateHandler;
768 if (0 == ex->terminateHandler)
770 ex->terminateHandler = terminateHandler;
772 info->globals.uncaughtExceptions++;
774 _Unwind_Reason_Code err = _Unwind_RaiseException(&ex->unwindHeader);
775 // The _Unwind_RaiseException() function should not return, it should
776 // unwind the stack past this function. If it does return, then something
778 report_failure(err, ex);
783 * ABI function for throwing an exception. Takes the object to be thrown (the
784 * pointer returned by __cxa_allocate_exception()), the type info for the
785 * pointee, and the destructor (if there is one) as arguments.
787 extern "C" void __cxa_throw(void *thrown_exception,
788 std::type_info *tinfo,
791 __cxa_exception *ex = reinterpret_cast<__cxa_exception*>(thrown_exception) - 1;
793 ex->referenceCount = 1;
794 ex->exceptionType = tinfo;
796 ex->exceptionDestructor = dest;
798 ex->unwindHeader.exception_class = exception_class;
799 ex->unwindHeader.exception_cleanup = exception_cleanup;
804 extern "C" void __cxa_rethrow_primary_exception(void* thrown_exception)
806 if (NULL == thrown_exception) { return; }
808 __cxa_exception *original = exceptionFromPointer(thrown_exception);
809 __cxa_dependent_exception *ex = reinterpret_cast<__cxa_dependent_exception*>(__cxa_allocate_dependent_exception())-1;
811 ex->primaryException = thrown_exception;
812 __cxa_increment_exception_refcount(thrown_exception);
814 ex->exceptionType = original->exceptionType;
815 ex->unwindHeader.exception_class = dependent_exception_class;
816 ex->unwindHeader.exception_cleanup = dependent_exception_cleanup;
818 throw_exception(reinterpret_cast<__cxa_exception*>(ex));
821 extern "C" void *__cxa_current_primary_exception(void)
823 __cxa_eh_globals* globals = __cxa_get_globals();
824 __cxa_exception *ex = globals->caughtExceptions;
826 if (0 == ex) { return NULL; }
827 ex = realExceptionFromException(ex);
828 __sync_fetch_and_add(&ex->referenceCount, 1);
832 extern "C" void __cxa_increment_exception_refcount(void* thrown_exception)
834 if (NULL == thrown_exception) { return; }
835 __cxa_exception *ex = static_cast<__cxa_exception*>(thrown_exception) - 1;
836 if (isDependentException(ex->unwindHeader.exception_class)) { return; }
837 __sync_fetch_and_add(&ex->referenceCount, 1);
839 extern "C" void __cxa_decrement_exception_refcount(void* thrown_exception)
841 if (NULL == thrown_exception) { return; }
842 __cxa_exception *ex = static_cast<__cxa_exception*>(thrown_exception) - 1;
843 releaseException(ex);
847 * ABI function. Rethrows the current exception. Does not remove the
848 * exception from the stack or decrement its handler count - the compiler is
849 * expected to set the landing pad for this function to the end of the catch
850 * block, and then call _Unwind_Resume() to continue unwinding once
851 * __cxa_end_catch() has been called and any cleanup code has been run.
853 extern "C" void __cxa_rethrow()
855 __cxa_thread_info *ti = thread_info();
856 __cxa_eh_globals *globals = &ti->globals;
857 // Note: We don't remove this from the caught list here, because
858 // __cxa_end_catch will be called when we unwind out of the try block. We
859 // could probably make this faster by providing an alternative rethrow
860 // function and ensuring that all cleanup code is run before calling it, so
861 // we can skip the top stack frame when unwinding.
862 __cxa_exception *ex = globals->caughtExceptions;
867 "Attempting to rethrow an exception that doesn't exist!\n");
871 if (ti->foreign_exception_state != __cxa_thread_info::none)
873 ti->foreign_exception_state = __cxa_thread_info::rethrown;
874 _Unwind_Exception *e = reinterpret_cast<_Unwind_Exception*>(ex);
875 _Unwind_Reason_Code err = _Unwind_Resume_or_Rethrow(e);
876 report_failure(err, ex);
880 assert(ex->handlerCount > 0 && "Rethrowing uncaught exception!");
882 // `globals->uncaughtExceptions` was decremented by `__cxa_begin_catch`.
883 // It's normally incremented by `throw_exception`, but this path invokes
884 // `_Unwind_Resume_or_Rethrow` directly to rethrow the exception.
885 // This path is only reachable if we're rethrowing a C++ exception -
886 // foreign exceptions don't adjust any of this state.
887 globals->uncaughtExceptions++;
889 // ex->handlerCount will be decremented in __cxa_end_catch in enclosing
892 // Make handler count negative. This will tell __cxa_end_catch that
893 // exception was rethrown and exception object should not be destroyed
894 // when handler count become zero
895 ex->handlerCount = -ex->handlerCount;
897 // Continue unwinding the stack with this exception. This should unwind to
898 // the place in the caller where __cxa_end_catch() is called. The caller
899 // will then run cleanup code and bounce the exception back with
901 _Unwind_Reason_Code err = _Unwind_Resume_or_Rethrow(&ex->unwindHeader);
902 report_failure(err, ex);
906 * Returns the type_info object corresponding to the filter.
908 static std::type_info *get_type_info_entry(_Unwind_Context *context,
912 // Get the address of the record in the table.
913 dw_eh_ptr_t record = lsda->type_table -
914 dwarf_size_of_fixed_size_field(lsda->type_table_encoding)*filter;
916 dw_eh_ptr_t start = record;
917 // Read the value, but it's probably an indirect reference...
918 int64_t offset = read_value(lsda->type_table_encoding, &record);
920 // (If the entry is 0, don't try to dereference it. That would be bad.)
921 if (offset == 0) { return 0; }
923 // ...so we need to resolve it
924 return reinterpret_cast<std::type_info*>(resolve_indirect_value(context,
925 lsda->type_table_encoding, offset, start));
931 * Checks the type signature found in a handler against the type of the thrown
932 * object. If ex is 0 then it is assumed to be a foreign exception and only
935 static bool check_type_signature(__cxa_exception *ex,
936 const std::type_info *type,
939 void *exception_ptr = static_cast<void*>(ex+1);
940 const std::type_info *ex_type = ex ? ex->exceptionType : 0;
942 bool is_ptr = ex ? ex_type->__is_pointer_p() : false;
945 exception_ptr = *static_cast<void**>(exception_ptr);
947 // Always match a catchall, even with a foreign exception
949 // Note: A 0 here is a catchall, not a cleanup, so we return true to
950 // indicate that we found a catch.
955 adjustedPtr = exception_ptr;
960 if (0 == ex) { return false; }
962 // If the types are the same, no casting is needed.
963 if (*type == *ex_type)
965 adjustedPtr = exception_ptr;
970 if (type->__do_catch(ex_type, &exception_ptr, 1))
972 adjustedPtr = exception_ptr;
979 * Checks whether the exception matches the type specifiers in this action
980 * record. If the exception only matches cleanups, then this returns false.
981 * If it matches a catch (including a catchall) then it returns true.
983 * The selector argument is used to return the selector that is passed in the
984 * second exception register when installing the context.
986 static handler_type check_action_record(_Unwind_Context *context,
988 dw_eh_ptr_t action_record,
990 unsigned long *selector,
993 if (!action_record) { return handler_cleanup; }
994 handler_type found = handler_none;
995 while (action_record)
997 int filter = read_sleb128(&action_record);
998 dw_eh_ptr_t action_record_offset_base = action_record;
999 int displacement = read_sleb128(&action_record);
1000 action_record = displacement ?
1001 action_record_offset_base + displacement : 0;
1002 // We only check handler types for C++ exceptions - foreign exceptions
1003 // are only allowed for cleanups and catchalls.
1006 std::type_info *handler_type = get_type_info_entry(context, lsda, filter);
1007 if (check_type_signature(ex, handler_type, adjustedPtr))
1010 return handler_catch;
1013 else if (filter < 0 && 0 != ex)
1015 bool matched = false;
1017 #if defined(__arm__) && !defined(__ARM_DWARF_EH__)
1019 std::type_info *handler_type = get_type_info_entry(context, lsda, filter--);
1020 while (handler_type)
1022 if (check_type_signature(ex, handler_type, adjustedPtr))
1027 handler_type = get_type_info_entry(context, lsda, filter--);
1030 unsigned char *type_index = reinterpret_cast<unsigned char*>(lsda->type_table) - filter - 1;
1033 std::type_info *handler_type = get_type_info_entry(context, lsda, *(type_index++));
1034 // If the exception spec matches a permitted throw type for
1035 // this function, don't report a handler - we are allowed to
1036 // propagate this exception out.
1037 if (check_type_signature(ex, handler_type, adjustedPtr))
1044 if (matched) { continue; }
1045 // If we don't find an allowed exception spec, we need to install
1046 // the context for this action. The landing pad will then call the
1047 // unexpected exception function. Treat this as a catch
1048 return handler_catch;
1050 else if (filter == 0)
1053 found = handler_cleanup;
1059 static void pushCleanupException(_Unwind_Exception *exceptionObject,
1060 __cxa_exception *ex)
1062 #if defined(__arm__) && !defined(__ARM_DWARF_EH__)
1063 __cxa_thread_info *info = thread_info_fast();
1067 if (ex->cleanupCount > 1)
1069 assert(exceptionObject == info->currentCleanup);
1072 ex->nextCleanup = info->currentCleanup;
1074 info->currentCleanup = exceptionObject;
1079 * The exception personality function. This is referenced in the unwinding
1080 * DWARF metadata and is called by the unwind library for each C++ stack frame
1081 * containing catch or cleanup code.
1084 BEGIN_PERSONALITY_FUNCTION(__gxx_personality_v0)
1085 // This personality function is for version 1 of the ABI. If you use it
1086 // with a future version of the ABI, it won't know what to do, so it
1087 // reports a fatal error and give up before it breaks anything.
1090 return _URC_FATAL_PHASE1_ERROR;
1092 __cxa_exception *ex = 0;
1093 __cxa_exception *realEx = 0;
1095 // If this exception is throw by something else then we can't make any
1096 // assumptions about its layout beyond the fields declared in
1097 // _Unwind_Exception.
1098 bool foreignException = !isCXXException(exceptionClass);
1100 // If this isn't a foreign exception, then we have a C++ exception structure
1101 if (!foreignException)
1103 ex = exceptionFromPointer(exceptionObject);
1104 realEx = realExceptionFromException(ex);
1107 #if defined(__arm__) && !defined(__ARM_DWARF_EH__)
1108 unsigned char *lsda_addr =
1109 static_cast<unsigned char*>(_Unwind_GetLanguageSpecificData(context));
1111 unsigned char *lsda_addr =
1112 reinterpret_cast<unsigned char*>(static_cast<uintptr_t>(_Unwind_GetLanguageSpecificData(context)));
1115 // No LSDA implies no landing pads - try the next frame
1116 if (0 == lsda_addr) { return continueUnwinding(exceptionObject, context); }
1118 // These two variables define how the exception will be handled.
1119 dwarf_eh_action action = {0};
1120 unsigned long selector = 0;
1122 // During the search phase, we do a complete lookup. If we return
1123 // _URC_HANDLER_FOUND, then the phase 2 unwind will call this function with
1124 // a _UA_HANDLER_FRAME action, telling us to install the handler frame. If
1125 // we return _URC_CONTINUE_UNWIND, we may be called again later with a
1126 // _UA_CLEANUP_PHASE action for this frame.
1128 // The point of the two-stage unwind allows us to entirely avoid any stack
1129 // unwinding if there is no handler. If there are just cleanups found,
1130 // then we can just panic call an abort function.
1132 // Matching a handler is much more expensive than matching a cleanup,
1133 // because we don't need to bother doing type comparisons (or looking at
1134 // the type table at all) for a cleanup. This means that there is no need
1135 // to cache the result of finding a cleanup, because it's (quite) quick to
1136 // look it up again from the action table.
1137 if (actions & _UA_SEARCH_PHASE)
1139 struct dwarf_eh_lsda lsda = parse_lsda(context, lsda_addr);
1141 if (!dwarf_eh_find_callsite(context, &lsda, &action))
1143 // EH range not found. This happens if exception is thrown and not
1144 // caught inside a cleanup (destructor). We should call
1145 // terminate() in this case. The catchTemp (landing pad) field of
1146 // exception object will contain null when personality function is
1147 // called with _UA_HANDLER_FRAME action for phase 2 unwinding.
1148 return _URC_HANDLER_FOUND;
1151 handler_type found_handler = check_action_record(context, &lsda,
1152 action.action_record, realEx, &selector, ex->adjustedPtr);
1153 // If there's no action record, we've only found a cleanup, so keep
1154 // searching for something real
1155 if (found_handler == handler_catch)
1157 // Cache the results for the phase 2 unwind, if we found a handler
1158 // and this is not a foreign exception.
1161 saveLandingPad(context, exceptionObject, ex, selector, action.landing_pad);
1162 ex->languageSpecificData = reinterpret_cast<const char*>(lsda_addr);
1163 ex->actionRecord = reinterpret_cast<const char*>(action.action_record);
1164 // ex->adjustedPtr is set when finding the action record.
1166 return _URC_HANDLER_FOUND;
1168 return continueUnwinding(exceptionObject, context);
1172 // If this is a foreign exception, we didn't have anywhere to cache the
1173 // lookup stuff, so we need to do it again. If this is either a forced
1174 // unwind, a foreign exception, or a cleanup, then we just install the
1175 // context for a cleanup.
1176 if (!(actions & _UA_HANDLER_FRAME))
1179 struct dwarf_eh_lsda lsda = parse_lsda(context, lsda_addr);
1180 dwarf_eh_find_callsite(context, &lsda, &action);
1181 if (0 == action.landing_pad) { return continueUnwinding(exceptionObject, context); }
1182 handler_type found_handler = check_action_record(context, &lsda,
1183 action.action_record, realEx, &selector, ex->adjustedPtr);
1184 // Ignore handlers this time.
1185 if (found_handler != handler_cleanup) { return continueUnwinding(exceptionObject, context); }
1186 pushCleanupException(exceptionObject, ex);
1188 else if (foreignException)
1190 struct dwarf_eh_lsda lsda = parse_lsda(context, lsda_addr);
1191 dwarf_eh_find_callsite(context, &lsda, &action);
1192 check_action_record(context, &lsda, action.action_record, realEx,
1193 &selector, ex->adjustedPtr);
1195 else if (ex->catchTemp == 0)
1197 // Uncaught exception in cleanup, calling terminate
1202 // Restore the saved info if we saved some last time.
1203 loadLandingPad(context, exceptionObject, ex, &selector, &action.landing_pad);
1205 ex->handlerSwitchValue = 0;
1209 _Unwind_SetIP(context, reinterpret_cast<unsigned long>(action.landing_pad));
1210 _Unwind_SetGR(context, __builtin_eh_return_data_regno(0),
1211 reinterpret_cast<unsigned long>(exceptionObject));
1212 _Unwind_SetGR(context, __builtin_eh_return_data_regno(1), selector);
1214 return _URC_INSTALL_CONTEXT;
1218 * ABI function called when entering a catch statement. The argument is the
1219 * pointer passed out of the personality function. This is always the start of
1220 * the _Unwind_Exception object. The return value for this function is the
1221 * pointer to the caught exception, which is either the adjusted pointer (for
1222 * C++ exceptions) of the unadjusted pointer (for foreign exceptions).
1224 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 4)
1225 extern "C" void *__cxa_begin_catch(void *e) throw()
1227 extern "C" void *__cxa_begin_catch(void *e)
1230 // We can't call the fast version here, because if the first exception that
1231 // we see is a foreign exception then we won't have called it yet.
1232 __cxa_thread_info *ti = thread_info();
1233 __cxa_eh_globals *globals = &ti->globals;
1234 _Unwind_Exception *exceptionObject = static_cast<_Unwind_Exception*>(e);
1236 if (isCXXException(exceptionObject->exception_class))
1238 // Only exceptions thrown with a C++ exception throwing function will
1239 // increment this, so don't decrement it here.
1240 globals->uncaughtExceptions--;
1241 __cxa_exception *ex = exceptionFromPointer(exceptionObject);
1243 if (ex->handlerCount == 0)
1245 // Add this to the front of the list of exceptions being handled
1246 // and increment its handler count so that it won't be deleted
1248 ex->nextException = globals->caughtExceptions;
1249 globals->caughtExceptions = ex;
1252 if (ex->handlerCount < 0)
1254 // Rethrown exception is catched before end of catch block.
1255 // Clear the rethrow flag (make value positive) - we are allowed
1256 // to delete this exception at the end of the catch block, as long
1257 // as it isn't thrown again later.
1269 // __cxa_begin_catch() <- we are here
1272 ex->handlerCount = -ex->handlerCount + 1;
1278 ti->foreign_exception_state = __cxa_thread_info::none;
1280 return ex->adjustedPtr;
1284 // If this is a foreign exception, then we need to be able to
1285 // store it. We can't chain foreign exceptions, so we give up
1286 // if there are already some outstanding ones.
1287 if (globals->caughtExceptions != 0)
1291 globals->caughtExceptions = reinterpret_cast<__cxa_exception*>(exceptionObject);
1292 ti->foreign_exception_state = __cxa_thread_info::caught;
1294 // exceptionObject is the pointer to the _Unwind_Exception within the
1295 // __cxa_exception. The throw object is after this
1296 return (reinterpret_cast<char*>(exceptionObject) + sizeof(_Unwind_Exception));
1302 * ABI function called when exiting a catch block. This will free the current
1303 * exception if it is no longer referenced in other catch blocks.
1305 extern "C" void __cxa_end_catch()
1307 // We can call the fast version here because the slow version is called in
1308 // __cxa_throw(), which must have been called before we end a catch block
1309 __cxa_thread_info *ti = thread_info_fast();
1310 __cxa_eh_globals *globals = &ti->globals;
1311 __cxa_exception *ex = globals->caughtExceptions;
1313 assert(0 != ex && "Ending catch when no exception is on the stack!");
1315 if (ti->foreign_exception_state != __cxa_thread_info::none)
1317 if (ti->foreign_exception_state != __cxa_thread_info::rethrown)
1319 _Unwind_Exception *e = reinterpret_cast<_Unwind_Exception*>(ti->globals.caughtExceptions);
1320 if (e->exception_cleanup)
1321 e->exception_cleanup(_URC_FOREIGN_EXCEPTION_CAUGHT, e);
1323 globals->caughtExceptions = 0;
1324 ti->foreign_exception_state = __cxa_thread_info::none;
1328 bool deleteException = true;
1330 if (ex->handlerCount < 0)
1332 // exception was rethrown. Exception should not be deleted even if
1333 // handlerCount become zero.
1343 // __cxa_end_catch(); <- we are here
1349 deleteException = false;
1356 if (ex->handlerCount == 0)
1358 globals->caughtExceptions = ex->nextException;
1359 if (deleteException)
1361 releaseException(ex);
1367 * ABI function. Returns the type of the current exception.
1369 extern "C" std::type_info *__cxa_current_exception_type()
1371 __cxa_eh_globals *globals = __cxa_get_globals();
1372 __cxa_exception *ex = globals->caughtExceptions;
1373 return ex ? ex->exceptionType : 0;
1377 * Cleanup, ensures that `__cxa_end_catch` is called to balance an explicit
1378 * `__cxa_begin_catch` call.
1380 static void end_catch(char *)
1385 * ABI function, called when an exception specification is violated.
1387 * This function does not return.
1389 extern "C" void __cxa_call_unexpected(void*exception)
1391 _Unwind_Exception *exceptionObject = static_cast<_Unwind_Exception*>(exception);
1392 // Wrap the call to the unexpected handler in calls to `__cxa_begin_catch`
1393 // and `__cxa_end_catch` so that we correctly update exception counts if
1394 // the unexpected handler throws an exception.
1395 __cxa_begin_catch(exceptionObject);
1396 __attribute__((cleanup(end_catch)))
1398 if (exceptionObject->exception_class == exception_class)
1400 __cxa_exception *ex = exceptionFromPointer(exceptionObject);
1401 if (ex->unexpectedHandler)
1403 ex->unexpectedHandler();
1404 // Should not be reached.
1409 // Should not be reached.
1414 * ABI function, returns the adjusted pointer to the exception object.
1416 extern "C" void *__cxa_get_exception_ptr(void *exceptionObject)
1418 return exceptionFromPointer(exceptionObject)->adjustedPtr;
1422 * As an extension, we provide the ability for the unexpected and terminate
1423 * handlers to be thread-local. We default to the standards-compliant
1424 * behaviour where they are global.
1426 static bool thread_local_handlers = false;
1432 * Sets whether unexpected and terminate handlers should be thread-local.
1434 void set_use_thread_local_handlers(bool flag) throw()
1436 thread_local_handlers = flag;
1439 * Sets a thread-local unexpected handler.
1441 unexpected_handler set_unexpected(unexpected_handler f) throw()
1443 static __cxa_thread_info *info = thread_info();
1444 unexpected_handler old = info->unexpectedHandler;
1445 info->unexpectedHandler = f;
1449 * Sets a thread-local terminate handler.
1451 terminate_handler set_terminate(terminate_handler f) throw()
1453 static __cxa_thread_info *info = thread_info();
1454 terminate_handler old = info->terminateHandler;
1455 info->terminateHandler = f;
1463 * Sets the function that will be called when an exception specification is
1466 unexpected_handler set_unexpected(unexpected_handler f) throw()
1468 if (thread_local_handlers) { return pathscale::set_unexpected(f); }
1470 return ATOMIC_SWAP(&unexpectedHandler, f);
1473 * Sets the function that is called to terminate the program.
1475 terminate_handler set_terminate(terminate_handler f) throw()
1477 if (thread_local_handlers) { return pathscale::set_terminate(f); }
1479 return ATOMIC_SWAP(&terminateHandler, f);
1482 * Terminates the program, calling a custom terminate implementation if
1487 static __cxa_thread_info *info = thread_info();
1488 if (0 != info && 0 != info->terminateHandler)
1490 info->terminateHandler();
1491 // Should not be reached - a terminate handler is not expected to
1498 * Called when an unexpected exception is encountered (i.e. an exception
1499 * violates an exception specification). This calls abort() unless a
1500 * custom handler has been set..
1504 static __cxa_thread_info *info = thread_info();
1505 if (0 != info && 0 != info->unexpectedHandler)
1507 info->unexpectedHandler();
1508 // Should not be reached - a terminate handler is not expected to
1512 unexpectedHandler();
1515 * Returns whether there are any exceptions currently being thrown that
1516 * have not been caught. This can occur inside a nested catch statement.
1518 bool uncaught_exception() throw()
1520 __cxa_thread_info *info = thread_info();
1521 return info->globals.uncaughtExceptions != 0;
1524 * Returns the number of exceptions currently being thrown that have not
1525 * been caught. This can occur inside a nested catch statement.
1527 int uncaught_exceptions() throw()
1529 __cxa_thread_info *info = thread_info();
1530 return info->globals.uncaughtExceptions;
1533 * Returns the current unexpected handler.
1535 unexpected_handler get_unexpected() throw()
1537 __cxa_thread_info *info = thread_info();
1538 if (info->unexpectedHandler)
1540 return info->unexpectedHandler;
1542 return ATOMIC_LOAD(&unexpectedHandler);
1545 * Returns the current terminate handler.
1547 terminate_handler get_terminate() throw()
1549 __cxa_thread_info *info = thread_info();
1550 if (info->terminateHandler)
1552 return info->terminateHandler;
1554 return ATOMIC_LOAD(&terminateHandler);
1557 #if defined(__arm__) && !defined(__ARM_DWARF_EH__)
1558 extern "C" _Unwind_Exception *__cxa_get_cleanup(void)
1560 __cxa_thread_info *info = thread_info_fast();
1561 _Unwind_Exception *exceptionObject = info->currentCleanup;
1562 if (isCXXException(exceptionObject->exception_class))
1564 __cxa_exception *ex = exceptionFromPointer(exceptionObject);
1566 if (ex->cleanupCount == 0)
1568 info->currentCleanup = ex->nextCleanup;
1569 ex->nextCleanup = 0;
1574 info->currentCleanup = 0;
1576 return exceptionObject;
1580 ".pushsection .text.__cxa_end_cleanup \n"
1581 ".global __cxa_end_cleanup \n"
1582 ".type __cxa_end_cleanup, \"function\" \n"
1583 "__cxa_end_cleanup: \n"
1584 " push {r1, r2, r3, r4} \n"
1585 " bl __cxa_get_cleanup \n"
1586 " push {r1, r2, r3, r4} \n"
1587 " b _Unwind_Resume \n"