--- old/src/hotspot/share/gc/shared/gc_globals.hpp	2020-01-17 17:08:34.673135738 +0100
+++ new/src/hotspot/share/gc/shared/gc_globals.hpp	2020-01-17 17:08:34.570135744 +0100
@@ -41,6 +41,9 @@
 #if INCLUDE_SERIALGC
 #include "gc/serial/serial_globals.hpp"
 #endif
+#if INCLUDE_SHENANDOAHGC
+#include "gc/shenandoah/shenandoah_globals.hpp"
+#endif
 #if INCLUDE_ZGC
 #include "gc/z/z_globals.hpp"
 #endif
@@ -140,6 +143,22 @@
     constraint,                                                             \
     writeable))                                                             \
                                                                             \
+  SHENANDOAHGC_ONLY(GC_SHENANDOAH_FLAGS(                                    \
+    develop,                                                                \
+    develop_pd,                                                             \
+    product,                                                                \
+    product_pd,                                                             \
+    diagnostic,                                                             \
+    diagnostic_pd,                                                          \
+    experimental,                                                           \
+    notproduct,                                                             \
+    manageable,                                                             \
+    product_rw,                                                             \
+    lp64_product,                                                           \
+    range,                                                                  \
+    constraint,                                                             \
+    writeable))                                                             \
+                                                                            \
   ZGC_ONLY(GC_Z_FLAGS(                                                      \
     develop,                                                                \
     develop_pd,                                                             \
@@ -179,6 +198,9 @@
   experimental(bool, UseZGC, false,                                         \
           "Use the Z garbage collector")                                    \
                                                                             \
+  experimental(bool, UseShenandoahGC, false,                                \
+          "Use the Shenandoah garbage collector")                           \
+                                                                            \
   product(uint, ParallelGCThreads, 0,                                       \
           "Number of parallel threads parallel gc will use")                \
           constraint(ParallelGCThreadsConstraintFunc,AfterErgo)             \