--- old/src/share/vm/runtime/arguments.cpp	2015-10-14 13:54:33.356426707 +0200
+++ new/src/share/vm/runtime/arguments.cpp	2015-10-14 13:54:33.221429972 +0200
@@ -51,6 +51,7 @@
 #include "utilities/macros.hpp"
 #include "utilities/stringUtils.hpp"
 #if INCLUDE_ALL_GCS
+#include "gc/shenandoah/shenandoahHeap.hpp"
 #include "gc/cms/compactibleFreeListSpace.hpp"
 #include "gc/g1/g1CollectedHeap.inline.hpp"
 #include "gc/parallel/parallelScavengeHeap.hpp"
@@ -1471,6 +1472,11 @@
   // the only value that can override MaxHeapSize if we are
   // to use UseCompressedOops is InitialHeapSize.
   size_t max_heap_size = MAX2(MaxHeapSize, InitialHeapSize);
+  if (UseShenandoahGC && FLAG_IS_DEFAULT(UseCompressedOops)) {
+    warning("Compressed Oops not supported with ShenandoahGC");
+    FLAG_SET_ERGO(bool, UseCompressedOops, false);
+    FLAG_SET_ERGO(bool, UseCompressedClassPointers, false);
+  }
 
   if (max_heap_size <= max_heap_for_compressed_oops()) {
 #if !defined(COMPILER1) || defined(TIERED)
@@ -1529,6 +1535,10 @@
     heap_alignment = ParallelScavengeHeap::conservative_max_heap_alignment();
   } else if (UseG1GC) {
     heap_alignment = G1CollectedHeap::conservative_max_heap_alignment();
+  } else if (UseShenandoahGC) {
+    // TODO: This sucks. Can't we have a clean interface to call the GC's collector
+    // policy for this?
+    heap_alignment = ShenandoahHeap::conservative_max_heap_alignment();
   }
 #endif // INCLUDE_ALL_GCS
   _conservative_max_heap_alignment = MAX4(heap_alignment,
@@ -1687,6 +1697,21 @@
   }
 }
 
+void Arguments::set_shenandoah_gc_flags() {
+  FLAG_SET_DEFAULT(UseDynamicNumberOfGCThreads, true);
+  FLAG_SET_DEFAULT(ParallelGCThreads,
+                   Abstract_VM_Version::parallel_worker_threads());
+
+  if (FLAG_IS_DEFAULT(ConcGCThreads)) {
+    uint conc_threads = MAX2((uint) 1, ParallelGCThreads);
+    FLAG_SET_DEFAULT(ConcGCThreads, conc_threads);
+  }
+
+  if (FLAG_IS_DEFAULT(ParallelRefProcEnabled)) {
+    FLAG_SET_DEFAULT(ParallelRefProcEnabled, true);
+  }
+}
+
 #if !INCLUDE_ALL_GCS
 #ifdef ASSERT
 static bool verify_serial_gc_flags() {
@@ -1706,6 +1731,8 @@
     set_cms_and_parnew_gc_flags();
   } else if (UseG1GC) {
     set_g1_gc_flags();
+  } else if (UseShenandoahGC) {
+    set_shenandoah_gc_flags();
   }
   check_deprecated_gc_flags();
   if (AssumeMP && !UseSerialGC) {