1 /*
2 * Copyright (c) 2015, 2022, Red Hat, Inc. All rights reserved.
3 * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHBARRIERSET_INLINE_HPP
27 #define SHARE_GC_SHENANDOAH_SHENANDOAHBARRIERSET_INLINE_HPP
28
29 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
30
31 #include "gc/shared/accessBarrierSupport.inline.hpp"
32 #include "gc/shared/cardTable.hpp"
33 #include "gc/shenandoah/mode/shenandoahMode.hpp"
34 #include "gc/shenandoah/shenandoahAsserts.hpp"
35 #include "gc/shenandoah/shenandoahCardTable.hpp"
36 #include "gc/shenandoah/shenandoahCollectionSet.inline.hpp"
37 #include "gc/shenandoah/shenandoahForwarding.inline.hpp"
38 #include "gc/shenandoah/shenandoahGeneration.hpp"
39 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
40 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
41 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
42 #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
43 #include "memory/iterator.inline.hpp"
44 #include "oops/oop.inline.hpp"
45
46 template <DecoratorSet decorators, class T>
47 inline oop ShenandoahBarrierSet::load_reference_barrier_mutator(oop obj, T* load_addr) {
48 assert(ShenandoahLoadRefBarrier, "Should be enabled");
49
50 constexpr bool on_weak = HasDecorator<decorators, ON_WEAK_OOP_REF>::value;
51 constexpr bool on_phantom = HasDecorator<decorators, ON_PHANTOM_OOP_REF>::value;
52
53 // Handle nulls. Strong loads filtered nulls with cset checks.
54 // Weak/phantom loads need to check for nulls here.
55 if (on_weak || on_phantom) {
56 if (obj == nullptr) {
57 return nullptr;
58 }
59 } else {
60 assert(obj != nullptr, "Should have been filtered before");
61 }
62
63 // Prevent resurrection of unreachable phantom (i.e. weak-native) references.
64 if (on_phantom &&
65 _heap->is_concurrent_weak_root_in_progress() &&
66 _heap->is_in_active_generation(obj) &&
67 !_heap->marking_context()->is_marked(obj)) {
68 return nullptr;
69 }
70
71 // Prevent resurrection of unreachable weak references.
72 if (on_weak &&
73 _heap->is_concurrent_weak_root_in_progress() &&
74 _heap->is_in_active_generation(obj) &&
75 !_heap->marking_context()->is_marked_strong(obj)) {
76 return nullptr;
77 }
78
79 // Weak/phantom loads need additional cset check.
80 if (on_phantom || on_weak) {
81 if (!_heap->has_forwarded_objects() || !_heap->in_collection_set(obj)) {
82 return obj;
83 }
84 } else {
85 shenandoah_assert_in_cset(load_addr, obj);
86 }
87
88 oop fwd = ShenandoahForwarding::get_forwardee_mutator(obj);
89 if (obj == fwd) {
90 assert(_heap->is_evacuation_in_progress(), "evac should be in progress");
91 Thread* const t = Thread::current();
92 fwd = _heap->evacuate_object(obj, t);
93 }
94
95 if (load_addr != nullptr && fwd != obj) {
96 // Since we are here and we know the load address, update the reference.
97 ShenandoahHeap::atomic_update_oop(fwd, load_addr, obj);
98 }
99
100 return fwd;
101 }
102
103 inline oop ShenandoahBarrierSet::load_reference_barrier(oop obj) {
104 if (!ShenandoahLoadRefBarrier) {
105 return obj;
106 }
107 if (_heap->has_forwarded_objects() && _heap->in_collection_set(obj)) {
108 // Subsumes null-check
109 assert(obj != nullptr, "cset check must have subsumed null-check");
110 oop fwd = ShenandoahForwarding::get_forwardee(obj);
111 if (obj == fwd && _heap->is_evacuation_in_progress()) {
112 Thread* t = Thread::current();
113 return _heap->evacuate_object(obj, t);
114 }
115 return fwd;
116 }
117 return obj;
118 }
119
120 template <class T>
121 inline oop ShenandoahBarrierSet::load_reference_barrier(DecoratorSet decorators, oop obj, T* load_addr) {
122 if (obj == nullptr) {
123 return nullptr;
124 }
125
126 // Prevent resurrection of unreachable phantom (i.e. weak-native) references.
127 if ((decorators & ON_PHANTOM_OOP_REF) != 0 &&
128 _heap->is_concurrent_weak_root_in_progress() &&
129 _heap->is_in_active_generation(obj) &&
130 !_heap->marking_context()->is_marked(obj)) {
131 return nullptr;
132 }
133
134 // Prevent resurrection of unreachable weak references.
135 if ((decorators & ON_WEAK_OOP_REF) != 0 &&
136 _heap->is_concurrent_weak_root_in_progress() &&
137 _heap->is_in_active_generation(obj) &&
138 !_heap->marking_context()->is_marked_strong(obj)) {
139 return nullptr;
140 }
141
142 // Allow runtime to see unreachable objects that are visited during concurrent class-unloading.
143 if ((decorators & AS_NO_KEEPALIVE) != 0 &&
144 _heap->is_concurrent_weak_root_in_progress() &&
145 !_heap->marking_context()->is_marked(obj)) {
146 return obj;
147 }
148
149 oop fwd = load_reference_barrier(obj);
150 if (load_addr != nullptr && fwd != obj) {
151 // Since we are here and we know the load address, update the reference.
152 ShenandoahHeap::atomic_update_oop(fwd, load_addr, obj);
153 }
154
155 return fwd;
156 }
157
158 inline void ShenandoahBarrierSet::enqueue(oop obj, bool filter) {
159 assert(obj != nullptr, "checked by caller");
160 shenandoah_assert_correct(nullptr, obj);
161 assert(_satb_mark_queue_set.is_active(), "only get here when SATB active");
162
163 // Filter marked objects before hitting the SATB queues. The same predicate would
164 // be used by SATBMQ::filter to eliminate already marked objects downstream, but
165 // filtering here helps to avoid wasteful SATB queueing work to begin with.
166 if (filter && !_heap->requires_marking(obj)) return;
167
168 SATBMarkQueue& queue = ShenandoahThreadLocalData::satb_mark_queue(Thread::current());
169 _satb_mark_queue_set.enqueue_known_active(queue, obj);
170 }
171
172 template <DecoratorSet decorators, typename T>
173 inline void ShenandoahBarrierSet::satb_barrier(T *field) {
174 // Uninitialized and no-keepalive stores do not need barrier.
175 if (HasDecorator<decorators, IS_DEST_UNINITIALIZED>::value ||
176 HasDecorator<decorators, AS_NO_KEEPALIVE>::value) {
177 return;
178 }
179
180 // Stores to weak/phantom require no barrier. The original references would
181 // have been enqueued in the SATB buffer by the load barrier if they were needed.
182 if (HasDecorator<decorators, ON_WEAK_OOP_REF>::value ||
183 HasDecorator<decorators, ON_PHANTOM_OOP_REF>::value) {
184 return;
185 }
186
187 if (ShenandoahSATBBarrier && _heap->is_concurrent_mark_in_progress()) {
188 T heap_oop = RawAccess<>::oop_load(field);
189 if (!CompressedOops::is_null(heap_oop)) {
190 enqueue(CompressedOops::decode(heap_oop));
191 }
192 }
193 }
194
195 inline void ShenandoahBarrierSet::satb_enqueue(oop value) {
196 if (value != nullptr && ShenandoahSATBBarrier && _heap->is_concurrent_mark_in_progress()) {
197 enqueue(value);
198 }
199 }
200
201 inline void ShenandoahBarrierSet::keep_alive_if_weak(DecoratorSet decorators, oop value) {
202 assert((decorators & ON_UNKNOWN_OOP_REF) == 0, "Reference strength must be known");
203 const bool on_strong_oop_ref = (decorators & ON_STRONG_OOP_REF) != 0;
204 const bool peek = (decorators & AS_NO_KEEPALIVE) != 0;
205 if (!peek && !on_strong_oop_ref) {
206 satb_enqueue(value);
207 }
208 }
209
210 template <DecoratorSet decorators, typename T>
211 inline void ShenandoahBarrierSet::write_ref_field_post(T* field, oop new_value) {
212 assert(ShenandoahCardBarrier, "Should have been checked by caller");
213
214 if (new_value == nullptr) {
215 // Null reference stores do not require card mark.
216 return;
217 }
218
219 if (_heap->is_in_young(field)) {
220 // Young field stores do not require card mark.
221 return;
222 }
223
224 if (!_heap->is_in_young(new_value)) {
225 // Not an old->young reference store.
226 return;
227 }
228
229 volatile CardTable::CardValue* byte = card_table()->byte_for(field);
230 if (UseCondCardMark && (*byte == CardTable::dirty_card_val())) {
231 return;
232 }
233 *byte = CardTable::dirty_card_val();
234 }
235
236 template <typename T>
237 inline oop ShenandoahBarrierSet::oop_load(DecoratorSet decorators, T* addr) {
238 oop value = RawAccess<>::oop_load(addr);
239 value = load_reference_barrier(decorators, value, addr);
240 keep_alive_if_weak(decorators, value);
241 return value;
242 }
243
244 template <typename T>
245 inline oop ShenandoahBarrierSet::oop_cmpxchg(DecoratorSet decorators, T* addr, oop compare_value, oop new_value) {
246 shenandoah_assert_not_in_cset_except(nullptr, compare_value, (compare_value == nullptr || ShenandoahHeap::heap()->cancelled_gc()));
247 shenandoah_assert_not_in_cset_except(nullptr, new_value, (new_value == nullptr || ShenandoahHeap::heap()->cancelled_gc()));
248
249 // Handle the previous value through SATB, as we are about to perform the store.
250 oop prev = RawAccess<>::oop_load(addr);
251 satb_enqueue(prev);
252
253 // Perform LRB on location to fix it up for this and all following accesses.
254 // This guarantees there are no false negatives due to concurrent evacuation,
255 // and the value loaded later by CAS is sanitized by some LRB, or is null.
256 load_reference_barrier(decorators, prev, addr);
257
258 return RawAccess<>::oop_atomic_cmpxchg(addr, compare_value, new_value);
259 }
260
261 template <typename T>
262 inline oop ShenandoahBarrierSet::oop_xchg(DecoratorSet decorators, T* addr, oop new_value) {
263 shenandoah_assert_not_in_cset_except(nullptr, new_value, (new_value == nullptr || ShenandoahHeap::heap()->cancelled_gc()));
264
265 // Handle the previous value through SATB, as we are about to perform the store.
266 oop prev = RawAccess<>::oop_load(addr);
267 satb_enqueue(prev);
268
269 // Perform LRB on location to fix it up for this and all following accesses.
270 // This is purely opportunistic: we would not have any false negatives here.
271 // This guarantees the value loaded later by XCHG is sanitized by some LRB, or is null.
272 load_reference_barrier(decorators, prev, addr);
273
274 return RawAccess<>::oop_atomic_xchg(addr, new_value);
275 }
276
277 template <DecoratorSet decorators, typename BarrierSetT>
278 template <typename T>
279 inline oop ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_load_not_in_heap(T* addr) {
280 assert((decorators & ON_UNKNOWN_OOP_REF) == 0, "must be absent");
281 ShenandoahBarrierSet* const bs = ShenandoahBarrierSet::barrier_set();
282 return bs->oop_load(decorators, addr);
283 }
284
285 template <DecoratorSet decorators, typename BarrierSetT>
286 template <typename T>
287 inline oop ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_load_in_heap(T* addr) {
288 assert((decorators & ON_UNKNOWN_OOP_REF) == 0, "must be absent");
289 ShenandoahBarrierSet* const bs = ShenandoahBarrierSet::barrier_set();
290 return bs->oop_load(decorators, addr);
291 }
292
293 template <DecoratorSet decorators, typename BarrierSetT>
294 inline oop ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_load_in_heap_at(oop base, ptrdiff_t offset) {
295 ShenandoahBarrierSet* const bs = ShenandoahBarrierSet::barrier_set();
296 DecoratorSet resolved_decorators = AccessBarrierSupport::resolve_possibly_unknown_oop_ref_strength<decorators>(base, offset);
297 return bs->oop_load(resolved_decorators, AccessInternal::oop_field_addr<decorators>(base, offset));
298 }
299
300 template <DecoratorSet decorators, typename BarrierSetT>
301 template <typename T>
302 inline void ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_store_common(T* addr, oop value) {
303 shenandoah_assert_marked_if(nullptr, value,
304 !CompressedOops::is_null(value) && ShenandoahHeap::heap()->is_evacuation_in_progress()
305 && !(ShenandoahHeap::heap()->active_generation()->is_young()
306 && ShenandoahHeap::heap()->heap_region_containing(value)->is_old()));
307 shenandoah_assert_not_in_cset_if(addr, value, value != nullptr && !ShenandoahHeap::heap()->cancelled_gc());
308 ShenandoahBarrierSet* const bs = ShenandoahBarrierSet::barrier_set();
309 bs->satb_barrier<decorators>(addr);
310 Raw::oop_store(addr, value);
311 }
312
313 template <DecoratorSet decorators, typename BarrierSetT>
314 template <typename T>
315 inline void ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_store_not_in_heap(T* addr, oop value) {
316 assert((decorators & ON_UNKNOWN_OOP_REF) == 0, "Reference strength must be known");
317 oop_store_common(addr, value);
318 }
319
320 template <DecoratorSet decorators, typename BarrierSetT>
321 template <typename T>
322 inline void ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_store_in_heap(T* addr, oop value) {
323 shenandoah_assert_not_in_cset_loc_except(addr, ShenandoahHeap::heap()->cancelled_gc());
324 shenandoah_assert_not_forwarded_except (addr, value, value == nullptr || ShenandoahHeap::heap()->cancelled_gc() || !ShenandoahHeap::heap()->is_concurrent_mark_in_progress());
325
326 oop_store_common(addr, value);
327 if (ShenandoahCardBarrier) {
328 ShenandoahBarrierSet* bs = ShenandoahBarrierSet::barrier_set();
329 bs->write_ref_field_post<decorators>(addr, value);
330 }
331 }
332
333 template <DecoratorSet decorators, typename BarrierSetT>
334 inline void ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_store_in_heap_at(oop base, ptrdiff_t offset, oop value) {
335 oop_store_in_heap(AccessInternal::oop_field_addr<decorators>(base, offset), value);
336 }
337
338 template <DecoratorSet decorators, typename BarrierSetT>
339 template <typename T>
340 inline oop ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_atomic_cmpxchg_not_in_heap(T* addr, oop compare_value, oop new_value) {
341 assert((decorators & AS_NO_KEEPALIVE) == 0, "CAS only with keep-alive");
342 assert((decorators & ON_STRONG_OOP_REF) != 0, "CAS only for strong refs");
343 ShenandoahBarrierSet* bs = ShenandoahBarrierSet::barrier_set();
344 return bs->oop_cmpxchg(decorators, addr, compare_value, new_value);
345 }
346
347 template <DecoratorSet decorators, typename BarrierSetT>
348 template <typename T>
349 inline oop ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_atomic_cmpxchg_in_heap(T* addr, oop compare_value, oop new_value) {
350 assert((decorators & AS_NO_KEEPALIVE) == 0, "CAS only with keep-alive");
351 assert((decorators & ON_STRONG_OOP_REF) != 0, "CAS only for strong refs");
352 ShenandoahBarrierSet* bs = ShenandoahBarrierSet::barrier_set();
353 oop result = bs->oop_cmpxchg(decorators, addr, compare_value, new_value);
354 if (ShenandoahCardBarrier) {
355 bs->write_ref_field_post<decorators>(addr, new_value);
356 }
357 return result;
358 }
359
360 template <DecoratorSet decorators, typename BarrierSetT>
361 inline oop ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_atomic_cmpxchg_in_heap_at(oop base, ptrdiff_t offset, oop compare_value, oop new_value) {
362 assert((decorators & AS_NO_KEEPALIVE) == 0, "CAS only with keep-alive");
363 assert((decorators & (ON_STRONG_OOP_REF | ON_UNKNOWN_OOP_REF)) != 0, "CAS only for strong refs OR unknown refs (Unsafe)");
364 ShenandoahBarrierSet* bs = ShenandoahBarrierSet::barrier_set();
365
366 // Unsafe.compareAndExchange/Set come here with ON_UNKNOWN_OOP_REF set.
367 // These are normally strong refs, but one can use Unsafe on Reference.referent.
368 // We cannot deal with that case. If application does Unsafe operations on
369 // Reference.referent field, this likely breaks weak reference semantics already.
370 // We upgrade the access to strong in (sometimes futile) attempt to maintain heap
371 // integrity, and assert in debug builds for better diagnostics.
372 DecoratorSet resolved_decorators = AccessBarrierSupport::resolve_possibly_unknown_oop_ref_strength<decorators>(base, offset);
373 assert((resolved_decorators & ON_STRONG_OOP_REF) != 0, "Application error: CAS on weak location");
374 resolved_decorators = (resolved_decorators & ~ON_DECORATOR_MASK) | ON_STRONG_OOP_REF;
375
376 auto addr = AccessInternal::oop_field_addr<decorators>(base, offset);
377 oop result = bs->oop_cmpxchg(resolved_decorators, addr, compare_value, new_value);
378 if (ShenandoahCardBarrier) {
379 bs->write_ref_field_post<decorators>(addr, new_value);
380 }
381 return result;
382 }
383
384 template <DecoratorSet decorators, typename BarrierSetT>
385 template <typename T>
386 inline oop ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_atomic_xchg_not_in_heap(T* addr, oop new_value) {
387 assert((decorators & AS_NO_KEEPALIVE) == 0, "XCHG only with keep-alive");
388 assert((decorators & ON_STRONG_OOP_REF) != 0, "XCHG only for strong refs");
389 ShenandoahBarrierSet* bs = ShenandoahBarrierSet::barrier_set();
390 return bs->oop_xchg(decorators, addr, new_value);
391 }
392
393 template <DecoratorSet decorators, typename BarrierSetT>
394 template <typename T>
395 inline oop ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_atomic_xchg_in_heap(T* addr, oop new_value) {
396 assert((decorators & AS_NO_KEEPALIVE) == 0, "XCHG only with keep-alive");
397 assert((decorators & ON_STRONG_OOP_REF) != 0, "XCHG only for strong refs");
398 ShenandoahBarrierSet* bs = ShenandoahBarrierSet::barrier_set();
399 oop result = bs->oop_xchg(decorators, addr, new_value);
400 if (ShenandoahCardBarrier) {
401 bs->write_ref_field_post<decorators>(addr, new_value);
402 }
403 return result;
404 }
405
406 template <DecoratorSet decorators, typename BarrierSetT>
407 inline oop ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_atomic_xchg_in_heap_at(oop base, ptrdiff_t offset, oop new_value) {
408 assert((decorators & AS_NO_KEEPALIVE) == 0, "XCHG only with keep-alive");
409 assert((decorators & (ON_STRONG_OOP_REF | ON_UNKNOWN_OOP_REF)) != 0, "XCHG only for strong refs OR unknown refs (Unsafe)");
410 ShenandoahBarrierSet* bs = ShenandoahBarrierSet::barrier_set();
411
412 // Unsafe.getAndSet comes here with ON_UNKNOWN_OOP_REF set.
413 // These are normally strong refs, but one can use Unsafe on Reference.referent.
414 // We cannot deal with that case. If application does Unsafe operations on
415 // Reference.referent field, this likely breaks weak reference semantics already.
416 // We upgrade the access to strong in (sometimes futile) attempt to maintain heap
417 // integrity, and assert in debug builds for better diagnostics.
418 DecoratorSet resolved_decorators = AccessBarrierSupport::resolve_possibly_unknown_oop_ref_strength<decorators>(base, offset);
419 assert((resolved_decorators & ON_STRONG_OOP_REF) != 0, "Application error: XCHG on weak location");
420 resolved_decorators = (resolved_decorators & ~ON_DECORATOR_MASK) | ON_STRONG_OOP_REF;
421
422 auto addr = AccessInternal::oop_field_addr<decorators>(base, offset);
423 oop result = bs->oop_xchg(resolved_decorators, addr, new_value);
424 if (ShenandoahCardBarrier) {
425 bs->write_ref_field_post<decorators>(addr, new_value);
426 }
427 return result;
428 }
429
430 // Clone barrier support
431 template <bool EVAC>
432 class ShenandoahUpdateEvacForCloneOopClosure : public BasicOopIterateClosure {
433 private:
434 ShenandoahHeap* const _heap;
435 const ShenandoahCollectionSet* const _cset;
436 Thread* const _thread;
437
438 template <class T>
439 inline void do_oop_work(T* p) {
440 T o = RawAccess<>::oop_load(p);
441 if (!CompressedOops::is_null(o)) {
442 oop obj = CompressedOops::decode_not_null(o);
443 if (_cset->is_in(obj)) {
444 oop fwd = ShenandoahForwarding::get_forwardee(obj);
445 if (EVAC && obj == fwd) {
446 fwd = _heap->evacuate_object(obj, _thread);
447 }
448 shenandoah_assert_forwarded_except(p, obj, _heap->cancelled_gc());
449 ShenandoahHeap::atomic_update_oop(fwd, p, o);
450 obj = fwd;
451 }
452 }
453 }
454
455 public:
456 ShenandoahUpdateEvacForCloneOopClosure() :
457 _heap(ShenandoahHeap::heap()),
458 _cset(_heap->collection_set()),
459 _thread(Thread::current()) {}
460
461 virtual void do_oop(oop* p) { do_oop_work(p); }
462 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
463 };
464
465 template <bool EVAC>
466 void ShenandoahBarrierSet::clone_work(oop obj) {
467 if (need_bulk_update(cast_from_oop<HeapWord*>(obj))) {
468 ShenandoahUpdateEvacForCloneOopClosure<EVAC> cl;
469 obj->oop_iterate(&cl);
470 }
471 }
472
473 template <DecoratorSet decorators, typename BarrierSetT>
474 void ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::clone_in_heap(oop src, oop dst, size_t size) {
475 // Hot code path, called from compiler/runtime. Make sure fast path is fast.
476
477 // Fix up src before doing the copy, if needed.
478 const char gc_state = ShenandoahThreadLocalData::gc_state(Thread::current());
479 if (gc_state != 0 && ShenandoahCloneBarrier) {
480 ShenandoahBarrierSet* bs = ShenandoahBarrierSet::barrier_set();
481 if ((gc_state & ShenandoahHeap::EVACUATION) != 0) {
482 bs->clone_work<true>(src);
483 } else if ((gc_state & ShenandoahHeap::UPDATE_REFS) != 0) {
484 bs->clone_work<false>(src);
485 }
486 }
487
488 Raw::clone(src, dst, size);
489
490 // Current allocator never allocates in old, so clone destination is guaranteed to be in young.
491 // Otherwise we need card barriers.
492 shenandoah_assert_in_young_if(nullptr, dst, ShenandoahCardBarrier);
493 }
494
495 template <DecoratorSet decorators, typename BarrierSetT>
496 template <typename T>
497 OopCopyResult ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_arraycopy_in_heap(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
498 arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
499 size_t length) {
500 T* src = arrayOopDesc::obj_offset_to_raw(src_obj, src_offset_in_bytes, src_raw);
501 T* dst = arrayOopDesc::obj_offset_to_raw(dst_obj, dst_offset_in_bytes, dst_raw);
502
503 ShenandoahBarrierSet* bs = ShenandoahBarrierSet::barrier_set();
504 bs->arraycopy_barrier(src, dst, length);
505 OopCopyResult result = Raw::oop_arraycopy_in_heap(src_obj, src_offset_in_bytes, src_raw, dst_obj, dst_offset_in_bytes, dst_raw, length);
506 if (ShenandoahCardBarrier) {
507 bs->write_ref_array((HeapWord*) dst, length);
508 }
509 return result;
510 }
511
512 template <class T>
513 void ShenandoahBarrierSet::arraycopy_barrier(T* src, T* dst, size_t count) {
514 if (count == 0) {
515 // No elements to copy, no need for barrier
516 return;
517 }
518
519 const char gc_state = ShenandoahThreadLocalData::gc_state(Thread::current());
520 if ((gc_state & ShenandoahHeap::MARKING) != 0) {
521 // If marking old or young, we must evaluate the SATB barrier. This will be the only
522 // action if we are not marking old. If we are marking old, we must still evaluate the
523 // load reference barrier for a young collection.
524 if (_heap->mode()->is_generational()) {
525 arraycopy_marking<true>(dst, count);
526 } else {
527 arraycopy_marking<false>(dst, count);
528 }
529 }
530
531 if ((gc_state & ShenandoahHeap::EVACUATION) != 0) {
532 assert((gc_state & ShenandoahHeap::YOUNG_MARKING) == 0, "Cannot be marking young during evacuation");
533 arraycopy_evacuation(src, count);
534 } else if ((gc_state & ShenandoahHeap::UPDATE_REFS) != 0) {
535 assert((gc_state & ShenandoahHeap::YOUNG_MARKING) == 0, "Cannot be marking young during update-refs");
536 arraycopy_update(src, count);
537 }
538 }
539
540 template <bool IS_GENERATIONAL, class T>
541 void ShenandoahBarrierSet::arraycopy_marking(T* dst, size_t count) {
542 assert(_heap->is_concurrent_mark_in_progress(), "only during marking");
543 if (!ShenandoahSATBBarrier) {
544 return;
545 }
546
547 const ShenandoahMarkingContext* ctx = _heap->marking_context();
548 // Everything allocated above TAMS is alive and doesn't need the barrier to keep it that way
549 if (is_above_tams<IS_GENERATIONAL>(ctx, dst)) {
550 return;
551 }
552
553 assert(!_heap->has_forwarded_objects() || _heap->is_concurrent_old_mark_in_progress(), "Forwarded object status is sane");
554 Thread* thread = Thread::current();
555 SATBMarkQueue& queue = ShenandoahThreadLocalData::satb_mark_queue(thread);
556 T* end = dst + count;
557 for (T* elem_ptr = dst; elem_ptr < end; ++elem_ptr) {
558 T o = RawAccess<>::oop_load(elem_ptr);
559 if (!CompressedOops::is_null(o)) {
560 oop obj = CompressedOops::decode_not_null(o);
561 if (!ctx->is_marked_strong(obj)) {
562 _satb_mark_queue_set.enqueue_known_active(queue, obj);
563 }
564 }
565 }
566 }
567
568 template <bool IS_GENERATIONAL, class T>
569 bool ShenandoahBarrierSet::is_above_tams(const ShenandoahMarkingContext* ctx, T* dst) const {
570 // TAMS for an old region is unreliable during a young-only mark, so overwritten pointers in old dst arrays must
571 // be enqueued to preserve old->young referents copied in and overwritten after init mark. See JDK-8373116.
572 return ctx->allocated_after_mark_start(reinterpret_cast<HeapWord*>(dst))
573 && !(IS_GENERATIONAL
574 && _heap->heap_region_containing(dst)->is_old()
575 && _heap->is_concurrent_young_mark_in_progress());
576 }
577
578 inline bool ShenandoahBarrierSet::need_bulk_update(HeapWord* ary) const {
579 return ary < _heap->heap_region_containing(ary)->get_update_watermark();
580 }
581
582 template <class T>
583 void ShenandoahBarrierSet::arraycopy_evacuation(T* src, size_t count) {
584 assert(_heap->is_evacuation_in_progress(), "only during evacuation");
585 if (!need_bulk_update(reinterpret_cast<HeapWord*>(src))) {
586 return;
587 }
588
589 assert(_heap->has_forwarded_objects(), "Forwarded object status is sane");
590 Thread* thread = Thread::current();
591 const ShenandoahCollectionSet* const cset = _heap->collection_set();
592 T* end = src + count;
593 for (T* elem_ptr = src; elem_ptr < end; ++elem_ptr) {
594 T o = RawAccess<>::oop_load(elem_ptr);
595 if (!CompressedOops::is_null(o)) {
596 oop obj = CompressedOops::decode_not_null(o);
597 if (cset->is_in(obj)) {
598 oop fwd = ShenandoahForwarding::get_forwardee(obj);
599 if (obj == fwd) {
600 fwd = _heap->evacuate_object(obj, thread);
601 }
602 shenandoah_assert_forwarded_except(elem_ptr, obj, _heap->cancelled_gc());
603 ShenandoahHeap::atomic_update_oop(fwd, elem_ptr, o);
604 }
605 }
606 }
607 }
608
609 template <class T>
610 void ShenandoahBarrierSet::arraycopy_update(T* src, size_t count) {
611 assert(_heap->is_update_refs_in_progress(), "only during update-refs");
612 if (!need_bulk_update(reinterpret_cast<HeapWord*>(src))) {
613 return;
614 }
615
616 assert(_heap->has_forwarded_objects(), "Forwarded object status is sane");
617 const ShenandoahCollectionSet* const cset = _heap->collection_set();
618 T* end = src + count;
619 for (T* elem_ptr = src; elem_ptr < end; ++elem_ptr) {
620 T o = RawAccess<>::oop_load(elem_ptr);
621 if (!CompressedOops::is_null(o)) {
622 oop obj = CompressedOops::decode_not_null(o);
623 if (cset->is_in(obj)) {
624 oop fwd = ShenandoahForwarding::get_forwardee(obj);
625 shenandoah_assert_forwarded_except(elem_ptr, obj, _heap->cancelled_gc());
626 ShenandoahHeap::atomic_update_oop(fwd, elem_ptr, o);
627 }
628 }
629 }
630 }
631
632 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHBARRIERSET_INLINE_HPP