src/hotspot/share/memory/universe.hpp

*** 193,202 ****
--- 193,205 ----
    static struct NarrowPtrStruct _narrow_oop;
    // For UseCompressedClassPointers.
    static struct NarrowPtrStruct _narrow_klass;
    static address _narrow_ptrs_base;
  
+   // value type using klass alignment encoded as oop metadata
+   static int     _oop_metadata_valuetype_mask;
+ 
    // array of dummy objects used with +FullGCAlot
    debug_only(static objArrayOop _fullgc_alot_dummy_array;)
    // index of next entry to clear
    debug_only(static int         _fullgc_alot_dummy_next;)
  
*** 434,445 ****
--- 437,453 ----
    }
  
    static void     set_narrow_klass_shift(int shift)       {
      assert(shift == 0 || shift == LogKlassAlignmentInBytes, "invalid shift for klass ptrs");
      _narrow_klass._shift   = shift;
+     if (shift == LogKlassAlignmentInBytes) {
+       _oop_metadata_valuetype_mask = 1;
+     }
    }
  
+   static int oop_metadata_valuetype_mask() { return _oop_metadata_valuetype_mask; }
+ 
    // Reserve Java heap and determine CompressedOops mode
    static ReservedSpace reserve_heap(size_t heap_size, size_t alignment);
  
    // Historic gc information
    static size_t get_heap_capacity_at_last_gc()         { return _heap_capacity_at_last_gc; }