1107   // Dirty read, then double-check under a lock.

  1107   // Lazily create the _oop_map_cache at first request

  1108   if (_oop_map_cache == NULL) {

  1108   // Lock-free access requires load_ptr_acquire.

  1109     // Otherwise, allocate a new one.

  1109   OopMapCache* oop_map_cache =

  1110       static_cast<OopMapCache*>(OrderAccess::load_ptr_acquire(&_oop_map_cache));

  1111   if (oop_map_cache == NULL) {

  1111     // First time use. Allocate a cache in C heap

  1113     // Check if _oop_map_cache was allocated while we were waiting for this lock

  1112     if (_oop_map_cache == NULL) {

  1114     if ((oop_map_cache = _oop_map_cache) == NULL) {

  1113       // Release stores from OopMapCache constructor before assignment

  1115       oop_map_cache = new OopMapCache();

  1114       // to _oop_map_cache. C++ compilers on ppc do not emit the

  1116       // Ensure _oop_map_cache is stable, since it is examined without a lock

  1115       // required memory barrier only because of the volatile

  1117       OrderAccess::release_store_ptr(&_oop_map_cache, oop_map_cache);

  1116       // qualifier of _oop_map_cache.

  1118     }

  1117       OrderAccess::release_store_ptr(&_oop_map_cache, new OopMapCache());

  1119   }

  1118     }

  1120   // _oop_map_cache is constant after init; lookup below does its own locking.

  1119   }

  1121   oop_map_cache->lookup(method, bci, entry_for);

  1120   // _oop_map_cache is constant after init; lookup below does is own locking.

  1121   _oop_map_cache->lookup(method, bci, entry_for);