src/share/vm/opto/graphKit.cpp

rev 5127 : 8023597: Optimize G1 barriers code for unsafe load_store
Summary: Avoid loading old values in G1 pre-barriers for inlined unsafe load_store nodes.

*** 3549,3558 ****
--- 3549,3560 ----
      assert(pre_val == NULL, "loaded already?");
      assert(val_type != NULL, "need a type");
    } else {
      // In this case both val_type and alias_idx are unused.
      assert(pre_val != NULL, "must be loaded already");
+     // Nothing to be done if pre_val is null.
+     if (pre_val->bottom_type() == TypePtr::NULL_PTR) return;
      assert(pre_val->bottom_type()->basic_type() == T_OBJECT, "or we shouldn't be here");
    }
    assert(bt == T_OBJECT, "or we shouldn't be here");
  
    IdealKit ideal(this, true);