src/hotspot/share/oops/instanceKlass.cpp

rev 47404 : [mq]: load_ptr_acquire
rev 47406 : [mq]: assembler_cmpxchg

*** 1107,1126 ****
  
  
  void InstanceKlass::mask_for(const methodHandle& method, int bci,
    InterpreterOopMap* entry_for) {
    // Lazily create the _oop_map_cache at first request
!   // Lock-free access requires load_ptr_acquire.
!   OopMapCache* oop_map_cache =
!       static_cast<OopMapCache*>(OrderAccess::load_ptr_acquire(&_oop_map_cache));
    if (oop_map_cache == NULL) {
      MutexLocker x(OopMapCacheAlloc_lock);
      // Check if _oop_map_cache was allocated while we were waiting for this lock
      if ((oop_map_cache = _oop_map_cache) == NULL) {
        oop_map_cache = new OopMapCache();
        // Ensure _oop_map_cache is stable, since it is examined without a lock
!       OrderAccess::release_store_ptr(&_oop_map_cache, oop_map_cache);
      }
    }
    // _oop_map_cache is constant after init; lookup below does its own locking.
    oop_map_cache->lookup(method, bci, entry_for);
  }
--- 1107,1125 ----
  
  
  void InstanceKlass::mask_for(const methodHandle& method, int bci,
    InterpreterOopMap* entry_for) {
    // Lazily create the _oop_map_cache at first request
!   // Lock-free access requires load_acquire.
!   OopMapCache* oop_map_cache = OrderAccess::load_acquire(&_oop_map_cache);
    if (oop_map_cache == NULL) {
      MutexLocker x(OopMapCacheAlloc_lock);
      // Check if _oop_map_cache was allocated while we were waiting for this lock
      if ((oop_map_cache = _oop_map_cache) == NULL) {
        oop_map_cache = new OopMapCache();
        // Ensure _oop_map_cache is stable, since it is examined without a lock
!       OrderAccess::release_store(&_oop_map_cache, oop_map_cache);
      }
    }
    // _oop_map_cache is constant after init; lookup below does its own locking.
    oop_map_cache->lookup(method, bci, entry_for);
  }
*** 1670,1680 ****
    // We use a double-check locking idiom here because this cache is
    // performance sensitive. In the normal system, this cache only
    // transitions from NULL to non-NULL which is safe because we use
    // release_set_methods_jmethod_ids() to advertise the new cache.
    // A partially constructed cache should never be seen by a racing
!   // thread. We also use release_store_ptr() to save a new jmethodID
    // in the cache so a partially constructed jmethodID should never be
    // seen either. Cache reads of existing jmethodIDs proceed without a
    // lock, but cache writes of a new jmethodID requires uniqueness and
    // creation of the cache itself requires no leaks so a lock is
    // generally acquired in those two cases.
--- 1669,1679 ----
    // We use a double-check locking idiom here because this cache is
    // performance sensitive. In the normal system, this cache only
    // transitions from NULL to non-NULL which is safe because we use
    // release_set_methods_jmethod_ids() to advertise the new cache.
    // A partially constructed cache should never be seen by a racing
!   // thread. We also use release_store() to save a new jmethodID
    // in the cache so a partially constructed jmethodID should never be
    // seen either. Cache reads of existing jmethodIDs proceed without a
    // lock, but cache writes of a new jmethodID requires uniqueness and
    // creation of the cache itself requires no leaks so a lock is
    // generally acquired in those two cases.
*** 1829,1839 ****
      id = new_id;
  
      // The jmethodID cache can be read while unlocked so we have to
      // make sure the new jmethodID is complete before installing it
      // in the cache.
!     OrderAccess::release_store_ptr(&jmeths[idnum+1], id);
    } else {
      *to_dealloc_id_p = new_id; // save new id for later delete
    }
    return id;
  }
--- 1828,1838 ----
      id = new_id;
  
      // The jmethodID cache can be read while unlocked so we have to
      // make sure the new jmethodID is complete before installing it
      // in the cache.
!     OrderAccess::release_store(&jmeths[idnum+1], id);
    } else {
      *to_dealloc_id_p = new_id; // save new id for later delete
    }
    return id;
  }