150 !_heap->marking_context()->is_marked_strong(obj)) {
151 return nullptr;
152 }
153
154 // Allow runtime to see unreachable objects that are visited during concurrent class-unloading.
155 if ((decorators & AS_NO_KEEPALIVE) != 0 &&
156 _heap->is_concurrent_weak_root_in_progress() &&
157 !_heap->marking_context()->is_marked(obj)) {
158 return obj;
159 }
160
161 oop fwd = load_reference_barrier(obj);
162 if (load_addr != nullptr && fwd != obj) {
163 // Since we are here and we know the load address, update the reference.
164 ShenandoahHeap::atomic_update_oop(fwd, load_addr, obj);
165 }
166
167 return fwd;
168 }
169
170 inline void ShenandoahBarrierSet::enqueue(oop obj) {
171 assert(obj != nullptr, "checked by caller");
172 assert(_satb_mark_queue_set.is_active(), "only get here when SATB active");
173
174 // Filter marked objects before hitting the SATB queues. The same predicate would
175 // be used by SATBMQ::filter to eliminate already marked objects downstream, but
176 // filtering here helps to avoid wasteful SATB queueing work to begin with.
177 if (!_heap->requires_marking(obj)) return;
178
179 SATBMarkQueue& queue = ShenandoahThreadLocalData::satb_mark_queue(Thread::current());
180 _satb_mark_queue_set.enqueue_known_active(queue, obj);
181 }
182
183 template <DecoratorSet decorators, typename T>
184 inline void ShenandoahBarrierSet::satb_barrier(T *field) {
185 // Uninitialized and no-keepalive stores do not need barrier.
186 if (HasDecorator<decorators, IS_DEST_UNINITIALIZED>::value ||
187 HasDecorator<decorators, AS_NO_KEEPALIVE>::value) {
188 return;
189 }
190
191 // Stores to weak/phantom require no barrier. The original references would
192 // have been enqueued in the SATB buffer by the load barrier if they were needed.
193 if (HasDecorator<decorators, ON_WEAK_OOP_REF>::value ||
194 HasDecorator<decorators, ON_PHANTOM_OOP_REF>::value) {
195 return;
196 }
197
417
418 // Unsafe.getAndSet comes here with ON_UNKNOWN_OOP_REF set.
419 // These are normally strong refs, but one can use Unsafe on Reference.referent.
420 // We cannot deal with that case. If application does Unsafe operations on
421 // Reference.referent field, this likely breaks weak reference semantics already.
422 // We upgrade the access to strong in (sometimes futile) attempt to maintain heap
423 // integrity, and assert in debug builds for better diagnostics.
424 DecoratorSet resolved_decorators = AccessBarrierSupport::resolve_possibly_unknown_oop_ref_strength<decorators>(base, offset);
425 assert((resolved_decorators & ON_STRONG_OOP_REF) != 0, "Application error: XCHG on weak location");
426 resolved_decorators = (resolved_decorators & ~ON_DECORATOR_MASK) | ON_STRONG_OOP_REF;
427
428 auto addr = AccessInternal::oop_field_addr<decorators>(base, offset);
429 oop result = bs->oop_xchg(resolved_decorators, addr, new_value);
430 if (ShenandoahCardBarrier) {
431 bs->write_ref_field_post<decorators>(addr);
432 }
433 return result;
434 }
435
436 // Clone barrier support
437 template <DecoratorSet decorators, typename BarrierSetT>
438 void ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::clone_in_heap(oop src, oop dst, size_t size) {
439 if (ShenandoahCloneBarrier) {
440 ShenandoahBarrierSet::barrier_set()->clone_barrier_runtime(src);
441 }
442 Raw::clone(src, dst, size);
443 }
444
445 template <DecoratorSet decorators, typename BarrierSetT>
446 template <typename T>
447 OopCopyResult ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_arraycopy_in_heap(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
448 arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
449 size_t length) {
450 T* src = arrayOopDesc::obj_offset_to_raw(src_obj, src_offset_in_bytes, src_raw);
451 T* dst = arrayOopDesc::obj_offset_to_raw(dst_obj, dst_offset_in_bytes, dst_raw);
452
453 ShenandoahBarrierSet* bs = ShenandoahBarrierSet::barrier_set();
454 bs->arraycopy_barrier(src, dst, length);
455 OopCopyResult result = Raw::oop_arraycopy_in_heap(src_obj, src_offset_in_bytes, src_raw, dst_obj, dst_offset_in_bytes, dst_raw, length);
456 if (ShenandoahCardBarrier) {
457 bs->write_ref_array((HeapWord*) dst, length);
458 }
459 return result;
460 }
461
462 template <class T, bool HAS_FWD, bool EVAC, bool ENQUEUE>
|
150 !_heap->marking_context()->is_marked_strong(obj)) {
151 return nullptr;
152 }
153
154 // Allow runtime to see unreachable objects that are visited during concurrent class-unloading.
155 if ((decorators & AS_NO_KEEPALIVE) != 0 &&
156 _heap->is_concurrent_weak_root_in_progress() &&
157 !_heap->marking_context()->is_marked(obj)) {
158 return obj;
159 }
160
161 oop fwd = load_reference_barrier(obj);
162 if (load_addr != nullptr && fwd != obj) {
163 // Since we are here and we know the load address, update the reference.
164 ShenandoahHeap::atomic_update_oop(fwd, load_addr, obj);
165 }
166
167 return fwd;
168 }
169
170 inline void ShenandoahBarrierSet::enqueue(oop obj, bool filter) {
171 assert(obj != nullptr, "checked by caller");
172 shenandoah_assert_correct(nullptr, obj);
173 assert(_satb_mark_queue_set.is_active(), "only get here when SATB active");
174
175 // Filter marked objects before hitting the SATB queues. The same predicate would
176 // be used by SATBMQ::filter to eliminate already marked objects downstream, but
177 // filtering here helps to avoid wasteful SATB queueing work to begin with.
178 if (filter && !_heap->requires_marking(obj)) return;
179
180 SATBMarkQueue& queue = ShenandoahThreadLocalData::satb_mark_queue(Thread::current());
181 _satb_mark_queue_set.enqueue_known_active(queue, obj);
182 }
183
184 template <DecoratorSet decorators, typename T>
185 inline void ShenandoahBarrierSet::satb_barrier(T *field) {
186 // Uninitialized and no-keepalive stores do not need barrier.
187 if (HasDecorator<decorators, IS_DEST_UNINITIALIZED>::value ||
188 HasDecorator<decorators, AS_NO_KEEPALIVE>::value) {
189 return;
190 }
191
192 // Stores to weak/phantom require no barrier. The original references would
193 // have been enqueued in the SATB buffer by the load barrier if they were needed.
194 if (HasDecorator<decorators, ON_WEAK_OOP_REF>::value ||
195 HasDecorator<decorators, ON_PHANTOM_OOP_REF>::value) {
196 return;
197 }
198
418
419 // Unsafe.getAndSet comes here with ON_UNKNOWN_OOP_REF set.
420 // These are normally strong refs, but one can use Unsafe on Reference.referent.
421 // We cannot deal with that case. If application does Unsafe operations on
422 // Reference.referent field, this likely breaks weak reference semantics already.
423 // We upgrade the access to strong in (sometimes futile) attempt to maintain heap
424 // integrity, and assert in debug builds for better diagnostics.
425 DecoratorSet resolved_decorators = AccessBarrierSupport::resolve_possibly_unknown_oop_ref_strength<decorators>(base, offset);
426 assert((resolved_decorators & ON_STRONG_OOP_REF) != 0, "Application error: XCHG on weak location");
427 resolved_decorators = (resolved_decorators & ~ON_DECORATOR_MASK) | ON_STRONG_OOP_REF;
428
429 auto addr = AccessInternal::oop_field_addr<decorators>(base, offset);
430 oop result = bs->oop_xchg(resolved_decorators, addr, new_value);
431 if (ShenandoahCardBarrier) {
432 bs->write_ref_field_post<decorators>(addr);
433 }
434 return result;
435 }
436
437 // Clone barrier support
438 template <bool EVAC>
439 class ShenandoahUpdateEvacForCloneOopClosure : public BasicOopIterateClosure {
440 private:
441 ShenandoahHeap* const _heap;
442 const ShenandoahCollectionSet* const _cset;
443 Thread* const _thread;
444
445 template <class T>
446 inline void do_oop_work(T* p) {
447 T o = RawAccess<>::oop_load(p);
448 if (!CompressedOops::is_null(o)) {
449 oop obj = CompressedOops::decode_not_null(o);
450 if (_cset->is_in(obj)) {
451 oop fwd = ShenandoahForwarding::get_forwardee(obj);
452 if (EVAC && obj == fwd) {
453 fwd = _heap->evacuate_object(obj, _thread);
454 }
455 shenandoah_assert_forwarded_except(p, obj, _heap->cancelled_gc());
456 ShenandoahHeap::atomic_update_oop(fwd, p, o);
457 obj = fwd;
458 }
459 }
460 }
461
462 public:
463 ShenandoahUpdateEvacForCloneOopClosure() :
464 _heap(ShenandoahHeap::heap()),
465 _cset(_heap->collection_set()),
466 _thread(Thread::current()) {}
467
468 virtual void do_oop(oop* p) { do_oop_work(p); }
469 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
470 };
471
472 void ShenandoahBarrierSet::clone_evacuation(oop obj) {
473 assert(_heap->is_evacuation_in_progress(), "only during evacuation");
474 if (need_bulk_update(cast_from_oop<HeapWord*>(obj))) {
475 ShenandoahUpdateEvacForCloneOopClosure<true> cl;
476 obj->oop_iterate(&cl);
477 }
478 }
479
480 void ShenandoahBarrierSet::clone_update(oop obj) {
481 assert(_heap->is_update_refs_in_progress(), "only during update-refs");
482 if (need_bulk_update(cast_from_oop<HeapWord*>(obj))) {
483 ShenandoahUpdateEvacForCloneOopClosure<false> cl;
484 obj->oop_iterate(&cl);
485 }
486 }
487
488 template <DecoratorSet decorators, typename BarrierSetT>
489 void ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::clone_in_heap(oop src, oop dst, size_t size) {
490 // Hot code path, called from compiler/runtime. Make sure fast path is fast.
491
492 // Fix up src before doing the copy, if needed.
493 const char gc_state = ShenandoahThreadLocalData::gc_state(Thread::current());
494 if (gc_state != 0 && ShenandoahCloneBarrier) {
495 ShenandoahBarrierSet* bs = ShenandoahBarrierSet::barrier_set();
496 if ((gc_state & ShenandoahHeap::EVACUATION) != 0) {
497 bs->clone_evacuation(src);
498 } else if ((gc_state & ShenandoahHeap::UPDATE_REFS) != 0) {
499 bs->clone_update(src);
500 }
501 }
502
503 Raw::clone(src, dst, size);
504
505 // Current allocator never allocates in old, so clone destination is guaranteed to be in young.
506 // Otherwise we need card barriers.
507 shenandoah_assert_in_young_if(nullptr, dst, ShenandoahCardBarrier);
508 }
509
510 template <DecoratorSet decorators, typename BarrierSetT>
511 template <typename T>
512 OopCopyResult ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_arraycopy_in_heap(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
513 arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
514 size_t length) {
515 T* src = arrayOopDesc::obj_offset_to_raw(src_obj, src_offset_in_bytes, src_raw);
516 T* dst = arrayOopDesc::obj_offset_to_raw(dst_obj, dst_offset_in_bytes, dst_raw);
517
518 ShenandoahBarrierSet* bs = ShenandoahBarrierSet::barrier_set();
519 bs->arraycopy_barrier(src, dst, length);
520 OopCopyResult result = Raw::oop_arraycopy_in_heap(src_obj, src_offset_in_bytes, src_raw, dst_obj, dst_offset_in_bytes, dst_raw, length);
521 if (ShenandoahCardBarrier) {
522 bs->write_ref_array((HeapWord*) dst, length);
523 }
524 return result;
525 }
526
527 template <class T, bool HAS_FWD, bool EVAC, bool ENQUEUE>
|