--- old/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp	2020-04-03 22:13:07.543243900 +0200
+++ new/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp	2020-04-03 22:13:07.438244598 +0200
@@ -183,26 +183,32 @@
 class ShenandoahSATBAndRemarkCodeRootsThreadsClosure : public ThreadClosure {
 private:
   ShenandoahSATBBufferClosure* _satb_cl;
+  OopClosure*            const _cl;
   MarkingCodeBlobClosure*      _code_cl;
   uintx _claim_token;
 
 public:
-  ShenandoahSATBAndRemarkCodeRootsThreadsClosure(ShenandoahSATBBufferClosure* satb_cl, MarkingCodeBlobClosure* code_cl) :
-    _satb_cl(satb_cl), _code_cl(code_cl),
+  ShenandoahSATBAndRemarkCodeRootsThreadsClosure(ShenandoahSATBBufferClosure* satb_cl, OopClosure* cl, MarkingCodeBlobClosure* code_cl) :
+    _satb_cl(satb_cl), _cl(cl), _code_cl(code_cl),
     _claim_token(Threads::thread_claim_token()) {}
 
   void do_thread(Thread* thread) {
     if (thread->claim_threads_do(true, _claim_token)) {
       ShenandoahThreadLocalData::satb_mark_queue(thread).apply_closure_and_empty(_satb_cl);
-      if (_code_cl != NULL && thread->is_Java_thread()) {
-        // In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking
-        // however the liveness of oops reachable from nmethods have very complex lifecycles:
-        // * Alive if on the stack of an executing method
-        // * Weakly reachable otherwise
-        // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be
-        // live by the SATB invariant but other oops recorded in nmethods may behave differently.
-        JavaThread* jt = (JavaThread*)thread;
-        jt->nmethods_do(_code_cl);
+      if (thread->is_Java_thread()) {
+        if (_cl != NULL) {
+          ResourceMark rm;
+          thread->oops_do(_cl, _code_cl);
+        } else  if (_code_cl != NULL) {
+          // In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking
+          // however the liveness of oops reachable from nmethods have very complex lifecycles:
+          // * Alive if on the stack of an executing method
+          // * Weakly reachable otherwise
+          // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be
+          // live by the SATB invariant but other oops recorded in nmethods may behave differently.
+          JavaThread* jt = (JavaThread*)thread;
+          jt->nmethods_do(_code_cl);
+        }
       }
     }
   }
@@ -242,21 +248,20 @@
       ShenandoahSATBBufferClosure cl(q);
       SATBMarkQueueSet& satb_mq_set = ShenandoahBarrierSet::satb_mark_queue_set();
       while (satb_mq_set.apply_closure_to_completed_buffer(&cl));
-
-      if (heap->unload_classes() && !ShenandoahConcurrentRoots::can_do_concurrent_class_unloading()) {
-        if (heap->has_forwarded_objects()) {
-          ShenandoahMarkResolveRefsClosure resolve_mark_cl(q, rp);
-          MarkingCodeBlobClosure blobsCl(&resolve_mark_cl, !CodeBlobToOopClosure::FixRelocations);
-          ShenandoahSATBAndRemarkCodeRootsThreadsClosure tc(&cl, &blobsCl);
-          Threads::threads_do(&tc);
-        } else {
-          ShenandoahMarkRefsClosure mark_cl(q, rp);
-          MarkingCodeBlobClosure blobsCl(&mark_cl, !CodeBlobToOopClosure::FixRelocations);
-          ShenandoahSATBAndRemarkCodeRootsThreadsClosure tc(&cl, &blobsCl);
-          Threads::threads_do(&tc);
-        }
+      bool do_nmethods = heap->unload_classes() && !ShenandoahConcurrentRoots::can_do_concurrent_class_unloading();
+      if (heap->has_forwarded_objects()) {
+        ShenandoahMarkResolveRefsClosure resolve_mark_cl(q, rp);
+        MarkingCodeBlobClosure blobsCl(&resolve_mark_cl, !CodeBlobToOopClosure::FixRelocations);
+        ShenandoahSATBAndRemarkCodeRootsThreadsClosure tc(&cl,
+                                                          ShenandoahStoreValEnqueueBarrier ? &resolve_mark_cl : NULL,
+                                                          do_nmethods ? &blobsCl : NULL);
+        Threads::threads_do(&tc);
       } else {
-        ShenandoahSATBAndRemarkCodeRootsThreadsClosure tc(&cl, NULL);
+        ShenandoahMarkRefsClosure mark_cl(q, rp);
+        MarkingCodeBlobClosure blobsCl(&mark_cl, !CodeBlobToOopClosure::FixRelocations);
+        ShenandoahSATBAndRemarkCodeRootsThreadsClosure tc(&cl,
+                                                          ShenandoahStoreValEnqueueBarrier ? &mark_cl : NULL,
+                                                          do_nmethods ? &blobsCl : NULL);
         Threads::threads_do(&tc);
       }
     }