Remove explicit defintion of __cxa_exception

Author: qmfrederik

objcxx_eh.cc

@@ -519,31 +519,15 @@ 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;
     };
 }
 
@@ -553,13 +537,35 @@ extern "C"
 OBJC_PUBLIC
 void objc_exception_throw(id object)
 {
+	// 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 ();
@@ -568,7 +574,8 @@ void objc_exception_throw(id object)
         __cxa_init_primary_exception(exc, & __objc_id_type_info, eh_cleanup);
     header->referenceCount = 1;
 
-    _Unwind_Reason_Code err = _Unwind_RaiseException (&header->exc.unwindHeader);
+	_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);