--- old/src/hotspot/share/compiler/compilerDirectives.hpp	2018-06-08 19:45:20.300121982 +0200
+++ new/src/hotspot/share/compiler/compilerDirectives.hpp	2018-06-08 19:45:20.030110267 +0200
@@ -66,7 +66,8 @@
     cflags(VectorizeDebug,          uintx, 0, VectorizeDebug) \
     cflags(CloneMapDebug,           bool, false, CloneMapDebug) \
     cflags(IGVPrintLevel,           intx, PrintIdealGraphLevel, IGVPrintLevel) \
-    cflags(MaxNodeLimit,            intx, MaxNodeLimit, MaxNodeLimit)
+    cflags(MaxNodeLimit,            intx, MaxNodeLimit, MaxNodeLimit) \
+ZGC_ONLY(cflags(ZOptimizeLoadBarriers, bool, ZOptimizeLoadBarriers, ZOptimizeLoadBarriers))
 #else
   #define compilerdirectives_c2_flags(cflags)
 #endif