src/share/vm/gc/g1/g1SATBCardTableModRefBS.cpp

*** 252,256 ****
--- 252,305 ----
          }
        }
      }
    }
  }
+ 
+ void G1SATBCardTableModRefBS::write_ref_nmethod_post(oop* dst, nmethod* nm) {
+   oop obj = oopDesc::load_heap_oop(dst);
+   if (obj != NULL) {
+     G1CollectedHeap* g1h = G1CollectedHeap::heap();
+     HeapRegion* hr = g1h->heap_region_containing(obj);
+     hr->add_strong_code_root(nm);
+   }
+ }
+ 
+ class G1EnsureLastRefToRegion : public OopClosure {
+   G1CollectedHeap* _g1h;
+   HeapRegion* _hr;
+   oop* _dst;
+ 
+   bool _value;
+ public:
+   G1EnsureLastRefToRegion(G1CollectedHeap* g1h, HeapRegion* hr, oop* dst) :
+     _g1h(g1h), _hr(hr), _dst(dst), _value(true) {}
+ 
+   void do_oop(oop* p) {
+     if (_value && p != _dst) {
+       oop obj = oopDesc::load_heap_oop(p);
+       if (obj != NULL) {
+         HeapRegion* hr = _g1h->heap_region_containing(obj);
+         if (hr == _hr) {
+           // Another reference to the same region.
+           _value = false;
+         }
+       }
+     }
+   }
+   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
+   bool value() const        { return _value;  }
+ };
+ 
+ void G1SATBCardTableModRefBS::write_ref_nmethod_pre(oop* dst, nmethod* nm) {
+   oop obj = oopDesc::load_heap_oop(dst);
+   if (obj != NULL) {
+     G1CollectedHeap* g1h = G1CollectedHeap::heap();
+     HeapRegion* hr = g1h->heap_region_containing(obj);
+     G1EnsureLastRefToRegion ensure_last_ref(g1h, hr, dst);
+     nm->oops_do(&ensure_last_ref);
+     if (ensure_last_ref.value()) {
+       // Last reference to this region, remove the nmethod from the rset.
+       hr->remove_strong_code_root(nm);
+     }
+   }
+ }