Index: Jenkinsfile
===================================================================
--- Jenkinsfile	(revision d5631b3ed1950913233bb5192a0e073e7b47bc77)
+++ Jenkinsfile	(revision 8da7421f9652c1f5cd8904ca4911b9e44b1329cd)
@@ -127,5 +127,7 @@
 			}
 
-			sh "${SrcDir}/configure CXX=${Settings.Compiler.CXX} CC=${Settings.Compiler.CC} ${Settings.Architecture.flags} AR=gcc-ar RANLIB=gcc-ranlib ${targets} --quiet --prefix=${BuildDir}"
+			ast = Settings.NewAST ? "--enable-new-ast" : "--disable-new-ast"
+
+			sh "${SrcDir}/configure CXX=${Settings.Compiler.CXX} CC=${Settings.Compiler.CC} ${Settings.Architecture.flags} AR=gcc-ar RANLIB=gcc-ranlib ${targets} ${ast} --quiet --prefix=${BuildDir}"
 
 			// Configure libcfa
@@ -359,4 +361,5 @@
 	public final CC_Desc Compiler
 	public final Arch_Desc Architecture
+	public final Boolean NewAST
 	public final Boolean RunAllTests
 	public final Boolean RunBenchmark
@@ -410,4 +413,5 @@
 
 		this.IsSandbox          = (branch == "jenkins-sandbox")
+		this.NewAST             = param.NewAST
 		this.RunAllTests        = param.RunAllTests
 		this.RunBenchmark       = param.RunBenchmark
@@ -470,8 +474,13 @@
 				],												\
 				[$class: 'BooleanParameterDefinition',  						\
+					description: 'If true, build compiler using new AST', 		\
+					name: 'NewAST', 									\
+					defaultValue: false,  								\
+				], 												\
+				[$class: 'BooleanParameterDefinition',  						\
 					description: 'If false, only the quick test suite is ran', 		\
 					name: 'RunAllTests', 								\
 					defaultValue: false,  								\
-				], 												\
+				],
 				[$class: 'BooleanParameterDefinition',  						\
 					description: 'If true, jenkins also runs benchmarks', 		\
Index: libcfa/src/concurrency/kernel.cfa
===================================================================
--- libcfa/src/concurrency/kernel.cfa	(revision d5631b3ed1950913233bb5192a0e073e7b47bc77)
+++ libcfa/src/concurrency/kernel.cfa	(revision 8da7421f9652c1f5cd8904ca4911b9e44b1329cd)
@@ -252,4 +252,5 @@
 		/* paranoid */ verify( kernelTLS.this_thread == thrd_dst );
 		/* paranoid */ verify( thrd_dst->context.SP );
+		/* paranoid */ verify( thrd_dst->state != Halted );
 		/* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) < ((uintptr_t)__get_stack(thrd_dst->curr_cor)->base ) || thrd_dst->curr_cor == proc_cor, "ERROR : Destination $thread %p has been corrupted.\n StackPointer too small.\n", thrd_dst ); // add escape condition if we are setting up the processor
 		/* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) > ((uintptr_t)__get_stack(thrd_dst->curr_cor)->limit) || thrd_dst->curr_cor == proc_cor, "ERROR : Destination $thread %p has been corrupted.\n StackPointer too large.\n", thrd_dst ); // add escape condition if we are setting up the processor
@@ -287,7 +288,6 @@
 		if(unlikely(thrd_dst->state == Halted)) {
 			// The thread has halted, it should never be scheduled/run again
-			// We may need to wake someone up here since
-			unpark( this->destroyer );
-			this->destroyer = 0p;
+			// finish the thread
+			__thread_finish( thrd_dst );
 			break RUNNING;
 		}
@@ -448,9 +448,28 @@
 }
 
-// KERNEL ONLY
-void __leave_thread() {
-	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
-	returnToKernel();
-	abort();
+extern "C" {
+	// Leave the thread monitor
+	// last routine called by a thread.
+	// Should never return
+	void __cfactx_thrd_leave() {
+		$thread * thrd = TL_GET( this_thread );
+		$monitor * this = &thrd->self_mon;
+
+		// Lock the monitor now
+		lock( this->lock __cfaabi_dbg_ctx2 );
+
+		disable_interrupts();
+
+		thrd->state = Halted;
+
+		if( thrd != this->owner || this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
+
+		// Leave the thread
+		/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
+		returnToKernel();
+		abort();
+
+		// Control flow should never reach here!
+	}
 }
 
Index: libcfa/src/concurrency/kernel.hfa
===================================================================
--- libcfa/src/concurrency/kernel.hfa	(revision d5631b3ed1950913233bb5192a0e073e7b47bc77)
+++ libcfa/src/concurrency/kernel.hfa	(revision 8da7421f9652c1f5cd8904ca4911b9e44b1329cd)
@@ -79,8 +79,4 @@
 	// Handle to pthreads
 	pthread_t kernel_thread;
-
-	// RunThread data
-	// Action to do after a thread is ran
-	$thread * destroyer;
 
 	// Preemption data
Index: libcfa/src/concurrency/kernel/startup.cfa
===================================================================
--- libcfa/src/concurrency/kernel/startup.cfa	(revision d5631b3ed1950913233bb5192a0e073e7b47bc77)
+++ libcfa/src/concurrency/kernel/startup.cfa	(revision 8da7421f9652c1f5cd8904ca4911b9e44b1329cd)
@@ -474,5 +474,4 @@
 	this.cltr = &_cltr;
 	full_proc = true;
-	destroyer = 0p;
 	do_terminate = false;
 	preemption_alarm = 0p;
Index: libcfa/src/concurrency/kernel_private.hfa
===================================================================
--- libcfa/src/concurrency/kernel_private.hfa	(revision d5631b3ed1950913233bb5192a0e073e7b47bc77)
+++ libcfa/src/concurrency/kernel_private.hfa	(revision 8da7421f9652c1f5cd8904ca4911b9e44b1329cd)
@@ -39,6 +39,6 @@
 ;
 
-//Block current thread and release/wake-up the following resources
-void __leave_thread() __attribute__((noreturn));
+//release/wake-up the following resources
+void __thread_finish( $thread * thrd );
 
 //-----------------------------------------------------------------------------
Index: libcfa/src/concurrency/monitor.cfa
===================================================================
--- libcfa/src/concurrency/monitor.cfa	(revision d5631b3ed1950913233bb5192a0e073e7b47bc77)
+++ libcfa/src/concurrency/monitor.cfa	(revision 8da7421f9652c1f5cd8904ca4911b9e44b1329cd)
@@ -281,47 +281,29 @@
 }
 
-extern "C" {
-	// Leave the thread monitor
-	// last routine called by a thread.
-	// Should never return
-	void __cfactx_thrd_leave() {
-		$thread * thrd = TL_GET( this_thread );
-		$monitor * this = &thrd->self_mon;
-
-		// Lock the monitor now
-		lock( this->lock __cfaabi_dbg_ctx2 );
-
-		disable_interrupts();
-
-		thrd->state = Halted;
-
-		/* paranoid */ verifyf( thrd == this->owner, "Expected owner to be %p, got %p (r: %i, m: %p)", thrd, this->owner, this->recursion, this );
-
-		// Leaving a recursion level, decrement the counter
-		this->recursion -= 1;
-
-		// If we haven't left the last level of recursion
-		// it must mean there is an error
-		if( this->recursion != 0) { abort( "Thread internal monitor has unbalanced recursion" ); }
-
-		// Fetch the next thread, can be null
-		$thread * new_owner = next_thread( this );
-
-		// Release the monitor lock
-		unlock( this->lock );
-
-		// Unpark the next owner if needed
-		/* paranoid */ verifyf( !new_owner || new_owner == this->owner, "Expected owner to be %p, got %p (m: %p)", new_owner, this->owner, this );
-		/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
-		/* paranoid */ verify( ! kernelTLS.this_processor->destroyer );
-		/* paranoid */ verify( thrd->state == Halted );
-
-		kernelTLS.this_processor->destroyer = new_owner;
-
-		// Leave the thread
-		__leave_thread();
-
-		// Control flow should never reach here!
-	}
+void __thread_finish( $thread * thrd ) {
+	$monitor * this = &thrd->self_mon;
+
+	// Lock the monitor now
+	/* paranoid */ verify( this->lock.lock );
+	/* paranoid */ verifyf( thrd == this->owner, "Expected owner to be %p, got %p (r: %i, m: %p)", thrd, this->owner, this->recursion, this );
+	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
+	/* paranoid */ verify( thrd->state == Halted );
+	/* paranoid */ verify( this->recursion == 1 );
+
+	// Leaving a recursion level, decrement the counter
+	this->recursion -= 1;
+	this->owner = 0p;
+
+	// Fetch the next thread, can be null
+	$thread * new_owner = next_thread( this );
+
+	// Release the monitor lock
+	unlock( this->lock );
+
+	// Unpark the next owner if needed
+	/* paranoid */ verifyf( !new_owner || new_owner == this->owner, "Expected owner to be %p, got %p (m: %p)", new_owner, this->owner, this );
+	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
+	/* paranoid */ verify( thrd->state == Halted );
+	unpark( new_owner );
 }