8373116: Genshen: arraycopy_work should be always done for arrays in old gen during young concurrent marking

8372498: [genshen] gc/TestAllocHumongousFragment.java#generational causes intermittent SIGSEGV crashes

Reviewed-by: shade, wkemper
Backport-of: c9ab330

Author: Xiaolong Peng

src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.hpp

@@ -128,8 +128,8 @@ class ShenandoahBarrierSet: public BarrierSet {
   void write_ref_array(HeapWord* start, size_t count);
 
 private:
-  template <class T>
-  inline void arraycopy_marking(T* dst, size_t count);
+  template <bool IS_GENERATIONAL, class T>
+  void arraycopy_marking(T* dst, size_t count);
   template <class T>
   inline void arraycopy_evacuation(T* src, size_t count);
   template <class T>

src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.inline.hpp

@@ -429,7 +429,11 @@ void ShenandoahBarrierSet::arraycopy_barrier(T* src, T* dst, size_t count) {
     // If marking old or young, we must evaluate the SATB barrier. This will be the only
     // action if we are not marking old. If we are marking old, we must still evaluate the
     // load reference barrier for a young collection.
-    arraycopy_marking(dst, count);
+    if (_heap->mode()->is_generational()) {
+      arraycopy_marking<true>(dst, count);
+    } else {
+      arraycopy_marking<false>(dst, count);
+    }
   }
 
   if ((gc_state & ShenandoahHeap::EVACUATION) != 0) {
@@ -441,11 +445,12 @@ void ShenandoahBarrierSet::arraycopy_barrier(T* src, T* dst, size_t count) {
   }
 }
 
-template <class T>
+template <bool IS_GENERATIONAL, class T>
 void ShenandoahBarrierSet::arraycopy_marking(T* dst, size_t count) {
   assert(_heap->is_concurrent_mark_in_progress(), "only during marking");
   if (ShenandoahSATBBarrier) {
-    if (!_heap->marking_context()->allocated_after_mark_start(reinterpret_cast<HeapWord*>(dst))) {
+    if (!_heap->marking_context()->allocated_after_mark_start(reinterpret_cast<HeapWord*>(dst)) ||
+        (IS_GENERATIONAL && _heap->heap_region_containing(dst)->is_old() && _heap->is_concurrent_young_mark_in_progress())) {
       arraycopy_work<T, false, false, true>(dst, count);
     }
   }