diff -r 4ebc2e2fb97c -r 71c04702a3d5 src/hotspot/share/gc/g1/g1RootClosures.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/g1/g1RootClosures.cpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,129 @@
+/*
+ * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "gc/g1/g1OopClosures.inline.hpp"
+#include "gc/g1/g1RootClosures.hpp"
+#include "gc/g1/g1SharedClosures.hpp"
+
+// Closures used for standard G1 evacuation.
+class G1EvacuationClosures : public G1EvacuationRootClosures {
+  G1SharedClosures<G1MarkNone> _closures;
+
+public:
+  G1EvacuationClosures(G1CollectedHeap* g1h,
+                       G1ParScanThreadState* pss,
+                       bool gcs_are_young) :
+      _closures(g1h, pss, gcs_are_young, /* must_claim_cld */ false) {}
+
+  OopClosure* weak_oops()   { return &_closures._buffered_oops; }
+  OopClosure* strong_oops() { return &_closures._buffered_oops; }
+
+  CLDClosure* weak_clds()             { return &_closures._clds; }
+  CLDClosure* strong_clds()           { return &_closures._clds; }
+  CLDClosure* second_pass_weak_clds() { return NULL; }
+
+  CodeBlobClosure* strong_codeblobs()      { return &_closures._codeblobs; }
+  CodeBlobClosure* weak_codeblobs()        { return &_closures._codeblobs; }
+
+  void flush()                 { _closures._buffered_oops.done(); }
+  double closure_app_seconds() { return _closures._buffered_oops.closure_app_seconds(); }
+
+  OopClosure* raw_strong_oops() { return &_closures._oops; }
+
+  bool trace_metadata()         { return false; }
+};
+
+// Closures used during initial mark.
+// The treatment of "weak" roots is selectable through the template parameter,
+// this is usually used to control unloading of classes and interned strings.
+template <G1Mark MarkWeak>
+class G1InitialMarkClosures : public G1EvacuationRootClosures {
+  G1SharedClosures<G1MarkFromRoot> _strong;
+  G1SharedClosures<MarkWeak>       _weak;
+
+  // Filter method to help with returning the appropriate closures
+  // depending on the class template parameter.
+  template <G1Mark Mark, typename T>
+  T* null_if(T* t) {
+    if (Mark == MarkWeak) {
+      return NULL;
+    }
+    return t;
+  }
+
+public:
+  G1InitialMarkClosures(G1CollectedHeap* g1h,
+                        G1ParScanThreadState* pss) :
+      _strong(g1h, pss, /* process_only_dirty_klasses */ false, /* must_claim_cld */ true),
+      _weak(g1h, pss,   /* process_only_dirty_klasses */ false, /* must_claim_cld */ true) {}
+
+  OopClosure* weak_oops()   { return &_weak._buffered_oops; }
+  OopClosure* strong_oops() { return &_strong._buffered_oops; }
+
+  // If MarkWeak is G1MarkPromotedFromRoot then the weak CLDs must be processed in a second pass.
+  CLDClosure* weak_clds()             { return null_if<G1MarkPromotedFromRoot>(&_weak._clds); }
+  CLDClosure* strong_clds()           { return &_strong._clds; }
+
+  // If MarkWeak is G1MarkFromRoot then all CLDs are processed by the weak and strong variants
+  // return a NULL closure for the following specialized versions in that case.
+  CLDClosure* second_pass_weak_clds() { return null_if<G1MarkFromRoot>(&_weak._clds); }
+
+  CodeBlobClosure* strong_codeblobs()      { return &_strong._codeblobs; }
+  CodeBlobClosure* weak_codeblobs()        { return &_weak._codeblobs; }
+
+  void flush() {
+    _strong._buffered_oops.done();
+    _weak._buffered_oops.done();
+  }
+
+  double closure_app_seconds() {
+    return _strong._buffered_oops.closure_app_seconds() +
+           _weak._buffered_oops.closure_app_seconds();
+  }
+
+  OopClosure* raw_strong_oops() { return &_strong._oops; }
+
+  // If we are not marking all weak roots then we are tracing
+  // which metadata is alive.
+  bool trace_metadata()         { return MarkWeak == G1MarkPromotedFromRoot; }
+};
+
+G1EvacuationRootClosures* G1EvacuationRootClosures::create_root_closures(G1ParScanThreadState* pss, G1CollectedHeap* g1h) {
+  G1EvacuationRootClosures* res = create_root_closures_ext(pss, g1h);
+  if (res != NULL) {
+    return res;
+  }
+
+  if (g1h->collector_state()->during_initial_mark_pause()) {
+    if (ClassUnloadingWithConcurrentMark) {
+      res = new G1InitialMarkClosures<G1MarkPromotedFromRoot>(g1h, pss);
+    } else {
+      res = new G1InitialMarkClosures<G1MarkFromRoot>(g1h, pss);
+    }
+  } else {
+    res = new G1EvacuationClosures(g1h, pss, g1h->collector_state()->gcs_are_young());
+  }
+  return res;
+}