--- old/src/hotspot/share/adlc/formssel.cpp	2020-01-17 17:08:27.098136155 +0100
+++ new/src/hotspot/share/adlc/formssel.cpp	2020-01-17 17:08:26.998136161 +0100
@@ -778,6 +778,10 @@
        !strcmp(_matrule->_rChild->_opType,"LoadBarrierSlowReg") ||
        !strcmp(_matrule->_rChild->_opType,"LoadBarrierWeakSlowReg") ||
 #endif
+#if INCLUDE_SHENANDOAHGC
+       !strcmp(_matrule->_rChild->_opType,"ShenandoahCompareAndExchangeP") ||
+       !strcmp(_matrule->_rChild->_opType,"ShenandoahCompareAndExchangeN") ||
+#endif
        !strcmp(_matrule->_rChild->_opType,"CompareAndExchangeP") ||
        !strcmp(_matrule->_rChild->_opType,"CompareAndExchangeN")))  return true;
   else if ( is_ideal_load() == Form::idealP )                return true;
@@ -3502,6 +3506,9 @@
     "CompareAndSwapB", "CompareAndSwapS", "CompareAndSwapI", "CompareAndSwapL", "CompareAndSwapP", "CompareAndSwapN",
     "WeakCompareAndSwapB", "WeakCompareAndSwapS", "WeakCompareAndSwapI", "WeakCompareAndSwapL", "WeakCompareAndSwapP", "WeakCompareAndSwapN",
     "CompareAndExchangeB", "CompareAndExchangeS", "CompareAndExchangeI", "CompareAndExchangeL", "CompareAndExchangeP", "CompareAndExchangeN",
+#if INCLUDE_SHENANDOAHGC
+    "ShenandoahCompareAndSwapN", "ShenandoahCompareAndSwapP", "ShenandoahWeakCompareAndSwapP", "ShenandoahWeakCompareAndSwapN", "ShenandoahCompareAndExchangeP", "ShenandoahCompareAndExchangeN",
+#endif
     "StoreCM",
     "ClearArray",
     "GetAndSetB", "GetAndSetS", "GetAndAddI", "GetAndSetI", "GetAndSetP",