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8154750: Add missing OrderAccess operations to ClassLoaderData lock-free data structures

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Reviewed-by: kbarrett, coleenp, acorn
This commit is contained in:
David Holmes 2016-06-02 23:37:09 -04:00
parent e8db159098
commit c301fb7188
3 changed files with 96 additions and 76 deletions
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24
hotspot/src/share/vm/oops/instanceKlass.cpp
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@ -1104,21 +1104,21 @@ void InstanceKlass::call_class_initializer_impl(instanceKlassHandle this_k, TRAP
void InstanceKlass::mask_for(const methodHandle& method, int bci,
InterpreterOopMap* entry_for) {
// Dirty read, then double-check under a lock.
if (_oop_map_cache == NULL) {
// Otherwise, allocate a new one.
// 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);
// First time use. Allocate a cache in C heap
if (_oop_map_cache == NULL) {
// Release stores from OopMapCache constructor before assignment
// to _oop_map_cache. C++ compilers on ppc do not emit the
// required memory barrier only because of the volatile
// qualifier of _oop_map_cache.
OrderAccess::release_store_ptr(&_oop_map_cache, new OopMapCache());
// 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 is own locking.
_oop_map_cache->lookup(method, bci, entry_for);
// _oop_map_cache is constant after init; lookup below does its own locking.
oop_map_cache->lookup(method, bci, entry_for);
}