Layout

Author: qmfrederik

objcxx_eh.cc

@@ -519,32 +519,16 @@ static void eh_cleanup(void *exception)
 	objc_release(*(id*)exception);
 }
 
-namespace __cxxabiv1
+static void eh_cleanup_noop(void *exception)
 {
-    struct __cxa_exception
-    {
-		// Manage the exception object itself.
-		std::type_info *exceptionType;
-		void (*exceptionDestructor)(void *);
-		terminate_handler unexpectedHandler;
-		terminate_handler terminateHandler;
-		__cxa_exception *nextException;
-		int handlerCount;
-		int handlerSwitchValue;
-		const unsigned char *actionRecord;
-		const unsigned char *languageSpecificData;
-		void *catchTemp;
-		void *adjustedPtr;
-		_Unwind_Exception unwindHeader;
-    };
+}
 
+namespace __cxxabiv1
+{
 	struct __cxa_refcounted_exception
-    {
-        // Manage this header.
-        int referenceCount;
-        // __cxa_exception must be last, and no padding can be after it.
-        __cxa_exception exc;
-    };
+	{
+		int referenceCount;
+	};
 }
 
 extern "C" __cxa_refcounted_exception* __cxa_init_primary_exception(void *obj, std::type_info *tinfo, void (*dest) (void *));
@@ -553,32 +537,55 @@ extern "C"
 OBJC_PUBLIC
 void objc_exception_throw(id object)
 {
-    id *exc = (id *)__cxa_allocate_exception(sizeof(id));
-    *exc = object;
-    objc_retain(object);
-    DEBUG_LOG("objc_exception_throw: Throwing 0x%x\n", *exc);
+	// Don't bother with a mutex here.  It doesn't matter if two threads set
+	// these values at the same time.
+	if (!done_setup)
+	{
+		DEBUG_LOG("objc_exception_throw: Doing initial setup\n");
+		MagicValueHolder *magicExc = (MagicValueHolder *)__cxa_allocate_exception(sizeof(MagicValueHolder));
+		MagicValueHolder x;
+		*magicExc = x;
+
+		__cxa_refcounted_exception *header =
+			__cxa_init_primary_exception(magicExc, & __objc_id_type_info, NULL);
+
+		type_info_offset = find_forwards(header, & __objc_id_type_info);
+		exception_struct_size = find_forwards(header, MagicValueHolder::magic);
+		__cxa_free_exception(magicExc);
+		
+		DEBUG_LOG("objc_exception_throw: type_info_offset: 0x%x\n", unsigned(type_info_offset));
+		DEBUG_LOG("objc_exception_throw: exception_struct_size: 0x%x\n", unsigned(exception_struct_size));
+
+		done_setup = true;
+	}
+
+	id *exc = (id *)__cxa_allocate_exception(sizeof(id));
+	*exc = object;
+	objc_retain(object);
+	DEBUG_LOG("objc_exception_throw: Throwing 0x%x\n", *exc);
 
 #ifndef __GLIBCXX__
-	// At the moment, only libstdc++ exposes __cxa_init_primary_exception
+	// At the moment, only libstdc++ exposes __cxa_init_primary_exception.
 	__cxa_throw(exc, & __objc_id_type_info, eh_cleanup);
 #else
-    __cxa_eh_globals *globals = __cxa_get_globals ();
-    globals->uncaughtExceptions += 1;
-    __cxa_refcounted_exception *header =
-        __cxa_init_primary_exception(exc, & __objc_id_type_info, eh_cleanup);
-    header->referenceCount = 1;
-
-    _Unwind_Reason_Code err = _Unwind_RaiseException (&header->exc.unwindHeader);
-
-    DEBUG_LOG("objc_exception_throw: _Unwind_RaiseException returned 0x%x for exception 0x%x\n", err, *exc);
-
-    if (_URC_END_OF_STACK == err && 0 != _objc_unexpected_exception)
-    {
-        DEBUG_LOG("Invoking _objc_unexpected_exception\n");
-        _objc_unexpected_exception(object);
-    }
-    DEBUG_LOG("Throw returned %d\n",(int) err);
-    abort();
+	__cxa_eh_globals *globals = __cxa_get_globals ();
+	globals->uncaughtExceptions += 1;
+	__cxa_refcounted_exception *header =
+		__cxa_init_primary_exception(exc, & __objc_id_type_info, eh_cleanup);
+	header->referenceCount = 1;
+
+	_Unwind_Exception *unwindHeader = pointer_add<_Unwind_Exception>(header, exception_struct_size - sizeof(_Unwind_Exception));
+	_Unwind_Reason_Code err = _Unwind_RaiseException (unwindHeader);
+
+	DEBUG_LOG("objc_exception_throw: _Unwind_RaiseException returned 0x%x for exception 0x%x\n", err, *exc);
+
+	if (_URC_END_OF_STACK == err && 0 != _objc_unexpected_exception)
+	{
+		DEBUG_LOG("Invoking _objc_unexpected_exception\n");
+		_objc_unexpected_exception(object);
+	}
+	DEBUG_LOG("Throw returned %d\n",(int) err);
+	abort();
 #endif
 }