1 /*
2 * Copyright (c) 2015, 2020, Red Hat, Inc. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
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23 */
24
25 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP
26 #define SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP
27
28 #include "gc/shenandoah/shenandoahHeap.hpp"
29
30 #include "classfile/javaClasses.inline.hpp"
31 #include "gc/shared/markBitMap.inline.hpp"
32 #include "gc/shared/threadLocalAllocBuffer.inline.hpp"
33 #include "gc/shared/continuationGCSupport.inline.hpp"
34 #include "gc/shared/suspendibleThreadSet.hpp"
35 #include "gc/shared/tlab_globals.hpp"
36 #include "gc/shenandoah/shenandoahAsserts.hpp"
37 #include "gc/shenandoah/shenandoahBarrierSet.inline.hpp"
38 #include "gc/shenandoah/shenandoahCollectionSet.inline.hpp"
39 #include "gc/shenandoah/shenandoahForwarding.inline.hpp"
40 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
41 #include "gc/shenandoah/shenandoahHeapRegionSet.inline.hpp"
42 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
43 #include "gc/shenandoah/shenandoahControlThread.hpp"
44 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
45 #include "gc/shenandoah/shenandoahScanRemembered.inline.hpp"
46 #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
47 #include "gc/shenandoah/shenandoahScanRemembered.inline.hpp"
48 #include "gc/shenandoah/mode/shenandoahMode.hpp"
49 #include "oops/compressedOops.inline.hpp"
50 #include "oops/oop.inline.hpp"
51 #include "runtime/atomic.hpp"
52 #include "runtime/javaThread.hpp"
53 #include "runtime/prefetch.inline.hpp"
54 #include "utilities/copy.hpp"
55 #include "utilities/globalDefinitions.hpp"
56
57 inline ShenandoahHeap* ShenandoahHeap::heap() {
58 return named_heap<ShenandoahHeap>(CollectedHeap::Shenandoah);
59 }
60
61 inline ShenandoahHeapRegion* ShenandoahRegionIterator::next() {
62 size_t new_index = Atomic::add(&_index, (size_t) 1, memory_order_relaxed);
63 // get_region() provides the bounds-check and returns null on OOB.
64 return _heap->get_region(new_index - 1);
65 }
66
67 inline bool ShenandoahHeap::has_forwarded_objects() const {
68 return _gc_state.is_set(HAS_FORWARDED);
69 }
70
71 inline WorkerThreads* ShenandoahHeap::workers() const {
72 return _workers;
73 }
74
75 inline WorkerThreads* ShenandoahHeap::safepoint_workers() {
76 return _safepoint_workers;
77 }
78
79 inline size_t ShenandoahHeap::heap_region_index_containing(const void* addr) const {
80 uintptr_t region_start = ((uintptr_t) addr);
81 uintptr_t index = (region_start - (uintptr_t) base()) >> ShenandoahHeapRegion::region_size_bytes_shift();
82 assert(index < num_regions(), "Region index is in bounds: " PTR_FORMAT, p2i(addr));
83 return index;
84 }
85
86 inline ShenandoahHeapRegion* const ShenandoahHeap::heap_region_containing(const void* addr) const {
87 size_t index = heap_region_index_containing(addr);
88 ShenandoahHeapRegion* const result = get_region(index);
89 assert(addr >= result->bottom() && addr < result->end(), "Heap region contains the address: " PTR_FORMAT, p2i(addr));
90 return result;
91 }
92
93 inline void ShenandoahHeap::enter_evacuation(Thread* t) {
94 _oom_evac_handler.enter_evacuation(t);
95 }
96
97 inline void ShenandoahHeap::leave_evacuation(Thread* t) {
98 _oom_evac_handler.leave_evacuation(t);
99 }
100
101 template <class T>
102 inline void ShenandoahHeap::update_with_forwarded(T* p) {
103 T o = RawAccess<>::oop_load(p);
104 if (!CompressedOops::is_null(o)) {
105 oop obj = CompressedOops::decode_not_null(o);
106 if (in_collection_set(obj)) {
107 // Corner case: when evacuation fails, there are objects in collection
108 // set that are not really forwarded. We can still go and try and update them
109 // (uselessly) to simplify the common path.
110 shenandoah_assert_forwarded_except(p, obj, cancelled_gc());
111 oop fwd = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
112 shenandoah_assert_not_in_cset_except(p, fwd, cancelled_gc());
113
114 // Unconditionally store the update: no concurrent updates expected.
115 RawAccess<IS_NOT_NULL>::oop_store(p, fwd);
116 }
117 }
118 }
119
120 template <class T>
121 inline void ShenandoahHeap::conc_update_with_forwarded(T* p) {
122 T o = RawAccess<>::oop_load(p);
123 if (!CompressedOops::is_null(o)) {
124 oop obj = CompressedOops::decode_not_null(o);
125 if (in_collection_set(obj)) {
126 // Corner case: when evacuation fails, there are objects in collection
127 // set that are not really forwarded. We can still go and try CAS-update them
128 // (uselessly) to simplify the common path.
129 shenandoah_assert_forwarded_except(p, obj, cancelled_gc());
130 oop fwd = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
131 shenandoah_assert_not_in_cset_except(p, fwd, cancelled_gc());
132
133 // Sanity check: we should not be updating the cset regions themselves,
134 // unless we are recovering from the evacuation failure.
135 shenandoah_assert_not_in_cset_loc_except(p, !is_in(p) || cancelled_gc());
136
137 // Either we succeed in updating the reference, or something else gets in our way.
138 // We don't care if that is another concurrent GC update, or another mutator update.
139 atomic_update_oop(fwd, p, obj);
140 }
141 }
142 }
143
144 // Atomic updates of heap location. This is only expected to work with updating the same
145 // logical object with its forwardee. The reason why we need stronger-than-relaxed memory
146 // ordering has to do with coordination with GC barriers and mutator accesses.
147 //
148 // In essence, stronger CAS access is required to maintain the transitive chains that mutator
149 // accesses build by themselves. To illustrate this point, consider the following example.
150 //
151 // Suppose "o" is the object that has a field "x" and the reference to "o" is stored
152 // to field at "addr", which happens to be Java volatile field. Normally, the accesses to volatile
153 // field at "addr" would be matched with release/acquire barriers. This changes when GC moves
154 // the object under mutator feet.
155 //
156 // Thread 1 (Java)
157 // // --- previous access starts here
158 // ...
159 // T1.1: store(&o.x, 1, mo_relaxed)
160 // T1.2: store(&addr, o, mo_release) // volatile store
161 //
162 // // --- new access starts here
163 // // LRB: copy and install the new copy to fwdptr
164 // T1.3: var copy = copy(o)
165 // T1.4: cas(&fwd, t, copy, mo_release) // pointer-mediated publication
166 // <access continues>
167 //
168 // Thread 2 (GC updater)
169 // T2.1: var f = load(&fwd, mo_{consume|acquire}) // pointer-mediated acquisition
170 // T2.2: cas(&addr, o, f, mo_release) // this method
171 //
172 // Thread 3 (Java)
173 // T3.1: var o = load(&addr, mo_acquire) // volatile read
174 // T3.2: if (o != null)
175 // T3.3: var r = load(&o.x, mo_relaxed)
176 //
177 // r is guaranteed to contain "1".
178 //
179 // Without GC involvement, there is synchronizes-with edge from T1.2 to T3.1,
180 // which guarantees this. With GC involvement, when LRB copies the object and
181 // another thread updates the reference to it, we need to have the transitive edge
182 // from T1.4 to T2.1 (that one is guaranteed by forwarding accesses), plus the edge
183 // from T2.2 to T3.1 (which is brought by this CAS).
184 //
185 // Note that we do not need to "acquire" in these methods, because we do not read the
186 // failure witnesses contents on any path, and "release" is enough.
187 //
188
189 inline void ShenandoahHeap::atomic_update_oop(oop update, oop* addr, oop compare) {
190 assert(is_aligned(addr, HeapWordSize), "Address should be aligned: " PTR_FORMAT, p2i(addr));
191 Atomic::cmpxchg(addr, compare, update, memory_order_release);
192 }
193
194 inline void ShenandoahHeap::atomic_update_oop(oop update, narrowOop* addr, narrowOop compare) {
195 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
196 narrowOop u = CompressedOops::encode(update);
197 Atomic::cmpxchg(addr, compare, u, memory_order_release);
198 }
199
200 inline void ShenandoahHeap::atomic_update_oop(oop update, narrowOop* addr, oop compare) {
201 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
202 narrowOop c = CompressedOops::encode(compare);
203 narrowOop u = CompressedOops::encode(update);
204 Atomic::cmpxchg(addr, c, u, memory_order_release);
205 }
206
207 inline bool ShenandoahHeap::atomic_update_oop_check(oop update, oop* addr, oop compare) {
208 assert(is_aligned(addr, HeapWordSize), "Address should be aligned: " PTR_FORMAT, p2i(addr));
209 return (oop) Atomic::cmpxchg(addr, compare, update, memory_order_release) == compare;
210 }
211
212 inline bool ShenandoahHeap::atomic_update_oop_check(oop update, narrowOop* addr, narrowOop compare) {
213 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
214 narrowOop u = CompressedOops::encode(update);
215 return (narrowOop) Atomic::cmpxchg(addr, compare, u, memory_order_release) == compare;
216 }
217
218 inline bool ShenandoahHeap::atomic_update_oop_check(oop update, narrowOop* addr, oop compare) {
219 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
220 narrowOop c = CompressedOops::encode(compare);
221 narrowOop u = CompressedOops::encode(update);
222 return CompressedOops::decode(Atomic::cmpxchg(addr, c, u, memory_order_release)) == compare;
223 }
224
225 // The memory ordering discussion above does not apply for methods that store nulls:
226 // then, there is no transitive reads in mutator (as we see nulls), and we can do
227 // relaxed memory ordering there.
228
229 inline void ShenandoahHeap::atomic_clear_oop(oop* addr, oop compare) {
230 assert(is_aligned(addr, HeapWordSize), "Address should be aligned: " PTR_FORMAT, p2i(addr));
231 Atomic::cmpxchg(addr, compare, oop(), memory_order_relaxed);
232 }
233
234 inline void ShenandoahHeap::atomic_clear_oop(narrowOop* addr, oop compare) {
235 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
236 narrowOop cmp = CompressedOops::encode(compare);
237 Atomic::cmpxchg(addr, cmp, narrowOop(), memory_order_relaxed);
238 }
239
240 inline void ShenandoahHeap::atomic_clear_oop(narrowOop* addr, narrowOop compare) {
241 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
242 Atomic::cmpxchg(addr, compare, narrowOop(), memory_order_relaxed);
243 }
244
245 inline bool ShenandoahHeap::cancelled_gc() const {
246 return _cancelled_gc.get() == CANCELLED;
247 }
248
249 inline bool ShenandoahHeap::check_cancelled_gc_and_yield(bool sts_active) {
250 if (! (sts_active && ShenandoahSuspendibleWorkers)) {
251 return cancelled_gc();
252 }
253
254 jbyte prev = _cancelled_gc.cmpxchg(NOT_CANCELLED, CANCELLABLE);
255 if (prev == CANCELLABLE || prev == NOT_CANCELLED) {
256 if (SuspendibleThreadSet::should_yield()) {
257 SuspendibleThreadSet::yield();
258 }
259
260 // Back to CANCELLABLE. The thread that poked NOT_CANCELLED first gets
261 // to restore to CANCELLABLE.
262 if (prev == CANCELLABLE) {
263 _cancelled_gc.set(CANCELLABLE);
264 }
265 return false;
266 } else {
267 return true;
268 }
269 }
270
271 inline void ShenandoahHeap::clear_cancelled_gc(bool clear_oom_handler) {
272 _cancelled_gc.set(CANCELLABLE);
273 if (_cancel_requested_time > 0) {
274 double cancel_time = os::elapsedTime() - _cancel_requested_time;
275 log_info(gc)("GC cancellation took %.3fs", cancel_time);
276 _cancel_requested_time = 0;
277 }
278
279 if (clear_oom_handler) {
280 _oom_evac_handler.clear();
281 }
282 }
283
284 inline HeapWord* ShenandoahHeap::allocate_from_gclab(Thread* thread, size_t size) {
285 assert(UseTLAB, "TLABs should be enabled");
286
287 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
288 if (gclab == nullptr) {
289 assert(!thread->is_Java_thread() && !thread->is_Worker_thread(),
290 "Performance: thread should have GCLAB: %s", thread->name());
291 // No GCLABs in this thread, fallback to shared allocation
292 return nullptr;
293 }
294 HeapWord* obj = gclab->allocate(size);
295 if (obj != nullptr) {
296 return obj;
297 }
298 return allocate_from_gclab_slow(thread, size);
299 }
300
301 inline HeapWord* ShenandoahHeap::allocate_from_plab(Thread* thread, size_t size, bool is_promotion) {
302 assert(UseTLAB, "TLABs should be enabled");
303
304 PLAB* plab = ShenandoahThreadLocalData::plab(thread);
305 HeapWord* obj;
306 if (plab == nullptr) {
307 assert(!thread->is_Java_thread() && !thread->is_Worker_thread(), "Performance: thread should have PLAB: %s", thread->name());
308 // No PLABs in this thread, fallback to shared allocation
309 return nullptr;
310 } else if (is_promotion && (plab->words_remaining() > 0) && !ShenandoahThreadLocalData::allow_plab_promotions(thread)) {
311 return nullptr;
312 }
313 // if plab->word_size() <= 0, thread's plab not yet initialized for this pass, so allow_plab_promotions() is not trustworthy
314 obj = plab->allocate(size);
315 if ((obj == nullptr) && (plab->words_remaining() < PLAB::min_size())) {
316 // allocate_from_plab_slow will establish allow_plab_promotions(thread) for future invocations
317 obj = allocate_from_plab_slow(thread, size, is_promotion);
318 }
319 // if plab->words_remaining() >= PLAB::min_size(), just return nullptr so we can use a shared allocation
320 if (obj == nullptr) {
321 return nullptr;
322 }
323
324 if (is_promotion) {
325 ShenandoahThreadLocalData::add_to_plab_promoted(thread, size * HeapWordSize);
326 } else {
327 ShenandoahThreadLocalData::add_to_plab_evacuated(thread, size * HeapWordSize);
328 }
329 return obj;
330 }
331
332 inline oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) {
333 assert(thread == Thread::current(), "Expected thread parameter to be current thread.");
334 if (ShenandoahThreadLocalData::is_oom_during_evac(thread)) {
335 // This thread went through the OOM during evac protocol and it is safe to return
336 // the forward pointer. It must not attempt to evacuate any more.
337 return ShenandoahBarrierSet::resolve_forwarded(p);
338 }
339
340 assert(ShenandoahThreadLocalData::is_evac_allowed(thread), "must be enclosed in oom-evac scope");
341
342 ShenandoahHeapRegion* r = heap_region_containing(p);
343 assert(!r->is_humongous(), "never evacuate humongous objects");
344
345 ShenandoahRegionAffiliation target_gen = r->affiliation();
346 if (mode()->is_generational() && ShenandoahHeap::heap()->is_gc_generation_young() &&
347 target_gen == YOUNG_GENERATION) {
348 markWord mark = p->mark();
349 if (mark.is_marked()) {
350 // Already forwarded.
351 return ShenandoahBarrierSet::resolve_forwarded(p);
352 }
353 if (mark.has_displaced_mark_helper()) {
354 // We don't want to deal with MT here just to ensure we read the right mark word.
355 // Skip the potential promotion attempt for this one.
356 } else if (r->age() + mark.age() >= InitialTenuringThreshold) {
357 oop result = try_evacuate_object(p, thread, r, OLD_GENERATION);
358 if (result != nullptr) {
359 return result;
360 }
361 // If we failed to promote this aged object, we'll fall through to code below and evacuate to young-gen.
362 }
363 }
364 return try_evacuate_object(p, thread, r, target_gen);
365 }
366
367 // try_evacuate_object registers the object and dirties the associated remembered set information when evacuating
368 // to OLD_GENERATION.
369 inline oop ShenandoahHeap::try_evacuate_object(oop p, Thread* thread, ShenandoahHeapRegion* from_region,
370 ShenandoahRegionAffiliation target_gen) {
371 bool alloc_from_lab = true;
372 bool has_plab = false;
373 HeapWord* copy = nullptr;
374 size_t size = p->size();
375 bool is_promotion = (target_gen == OLD_GENERATION) && from_region->is_young();
376
377 #ifdef ASSERT
378 if (ShenandoahOOMDuringEvacALot &&
379 (os::random() & 1) == 0) { // Simulate OOM every ~2nd slow-path call
380 copy = nullptr;
381 } else {
382 #endif
383 if (UseTLAB) {
384 switch (target_gen) {
385 case YOUNG_GENERATION: {
386 copy = allocate_from_gclab(thread, size);
387 if ((copy == nullptr) && (size < ShenandoahThreadLocalData::gclab_size(thread))) {
388 // GCLAB allocation failed because we are bumping up against the limit on young evacuation reserve. Try resetting
389 // the desired GCLAB size and retry GCLAB allocation to avoid cascading of shared memory allocations.
390 ShenandoahThreadLocalData::set_gclab_size(thread, PLAB::min_size());
391 copy = allocate_from_gclab(thread, size);
392 // If we still get nullptr, we'll try a shared allocation below.
393 }
394 break;
395 }
396 case OLD_GENERATION: {
397
398 PLAB* plab = ShenandoahThreadLocalData::plab(thread);
399 if (plab != nullptr) {
400 has_plab = true;
401 }
402 copy = allocate_from_plab(thread, size, is_promotion);
403 if ((copy == nullptr) && (size < ShenandoahThreadLocalData::plab_size(thread)) &&
404 ShenandoahThreadLocalData::plab_retries_enabled(thread)) {
405 // PLAB allocation failed because we are bumping up against the limit on old evacuation reserve or because
406 // the requested object does not fit within the current plab but the plab still has an "abundance" of memory,
407 // where abundance is defined as >= PLAB::min_size(). In the former case, we try resetting the desired
408 // PLAB size and retry PLAB allocation to avoid cascading of shared memory allocations.
409
410 // In this situation, PLAB memory is precious. We'll try to preserve our existing PLAB by forcing
411 // this particular allocation to be shared.
412 if (plab->words_remaining() < PLAB::min_size()) {
413 ShenandoahThreadLocalData::set_plab_size(thread, PLAB::min_size());
414 copy = allocate_from_plab(thread, size, is_promotion);
415 // If we still get nullptr, we'll try a shared allocation below.
416 if (copy == nullptr) {
417 // If retry fails, don't continue to retry until we have success (probably in next GC pass)
418 ShenandoahThreadLocalData::disable_plab_retries(thread);
419 }
420 }
421 // else, copy still equals nullptr. this causes shared allocation below, preserving this plab for future needs.
422 }
423 break;
424 }
425 default: {
426 ShouldNotReachHere();
427 break;
428 }
429 }
430 }
431
432 if (copy == nullptr) {
433 // If we failed to allocate in LAB, we'll try a shared allocation.
434 if (!is_promotion || !has_plab || (size > PLAB::min_size())) {
435 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared_gc(size, target_gen);
436 copy = allocate_memory(req, is_promotion);
437 alloc_from_lab = false;
438 }
439 // else, we leave copy equal to nullptr, signaling a promotion failure below if appropriate.
440 // We choose not to promote objects smaller than PLAB::min_size() by way of shared allocations, as this is too
441 // costly. Instead, we'll simply "evacuate" to young-gen memory (using a GCLAB) and will promote in a future
442 // evacuation pass. This condition is denoted by: is_promotion && has_plab && (size <= PLAB::min_size())
443 }
444 #ifdef ASSERT
445 }
446 #endif
447
448 if (copy == nullptr) {
449 if (target_gen == OLD_GENERATION) {
450 assert(mode()->is_generational(), "Should only be here in generational mode.");
451 if (from_region->is_young()) {
452 // Signal that promotion failed. Will evacuate this old object somewhere in young gen.
453 report_promotion_failure(thread, size);
454 handle_promotion_failure();
455 return nullptr;
456 } else {
457 // Remember that evacuation to old gen failed. We'll want to trigger a full gc to recover from this
458 // after the evacuation threads have finished.
459 handle_old_evacuation_failure();
460 }
461 }
462
463 control_thread()->handle_alloc_failure_evac(size);
464
465 _oom_evac_handler.handle_out_of_memory_during_evacuation();
466
467 return ShenandoahBarrierSet::resolve_forwarded(p);
468 }
469
470 // Copy the object:
471 _evac_tracker->begin_evacuation(thread, size * HeapWordSize);
472 Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(p), copy, size);
473
474 oop copy_val = cast_to_oop(copy);
475
476 if (mode()->is_generational() && target_gen == YOUNG_GENERATION && is_aging_cycle()) {
477 ShenandoahHeap::increase_object_age(copy_val, from_region->age() + 1);
478 }
479
480 // Try to install the new forwarding pointer.
481 ContinuationGCSupport::relativize_stack_chunk(copy_val);
482
483 oop result = ShenandoahForwarding::try_update_forwardee(p, copy_val);
484 if (result == copy_val) {
485 // Successfully evacuated. Our copy is now the public one!
486 _evac_tracker->end_evacuation(thread, size * HeapWordSize, ShenandoahHeap::get_object_age(copy_val));
487 if (mode()->is_generational() && target_gen == OLD_GENERATION) {
488 handle_old_evacuation(copy, size, from_region->is_young());
489 }
490 shenandoah_assert_correct(nullptr, copy_val);
491 return copy_val;
492 } else {
493 // Failed to evacuate. We need to deal with the object that is left behind. Since this
494 // new allocation is certainly after TAMS, it will be considered live in the next cycle.
495 // But if it happens to contain references to evacuated regions, those references would
496 // not get updated for this stale copy during this cycle, and we will crash while scanning
497 // it the next cycle.
498 if (alloc_from_lab) {
499 // For LAB allocations, it is enough to rollback the allocation ptr. Either the next
500 // object will overwrite this stale copy, or the filler object on LAB retirement will
501 // do this.
502 switch (target_gen) {
503 case YOUNG_GENERATION: {
504 ShenandoahThreadLocalData::gclab(thread)->undo_allocation(copy, size);
505 break;
506 }
507 case OLD_GENERATION: {
508 ShenandoahThreadLocalData::plab(thread)->undo_allocation(copy, size);
509 if (is_promotion) {
510 ShenandoahThreadLocalData::subtract_from_plab_promoted(thread, size * HeapWordSize);
511 } else {
512 ShenandoahThreadLocalData::subtract_from_plab_evacuated(thread, size * HeapWordSize);
513 }
514 break;
515 }
516 default: {
517 ShouldNotReachHere();
518 break;
519 }
520 }
521 } else {
522 // For non-LAB allocations, we have no way to retract the allocation, and
523 // have to explicitly overwrite the copy with the filler object. With that overwrite,
524 // we have to keep the fwdptr initialized and pointing to our (stale) copy.
525 fill_with_object(copy, size);
526 shenandoah_assert_correct(nullptr, copy_val);
527 // For non-LAB allocations, the object has already been registered
528 }
529 shenandoah_assert_correct(nullptr, result);
530 return result;
531 }
532 }
533
534 void ShenandoahHeap::increase_object_age(oop obj, uint additional_age) {
535 markWord w = obj->has_displaced_mark() ? obj->displaced_mark() : obj->mark();
536 w = w.set_age(MIN2(markWord::max_age, w.age() + additional_age));
537 if (obj->has_displaced_mark()) {
538 obj->set_displaced_mark(w);
539 } else {
540 obj->set_mark(w);
541 }
542 }
543
544 uint ShenandoahHeap::get_object_age(oop obj) {
545 markWord w = obj->has_displaced_mark() ? obj->displaced_mark() : obj->mark();
546 return w.age();
547 }
548
549 inline bool ShenandoahHeap::clear_old_evacuation_failure() {
550 return _old_gen_oom_evac.try_unset();
551 }
552
553 bool ShenandoahHeap::is_in(const void* p) const {
554 HeapWord* heap_base = (HeapWord*) base();
555 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
556 return p >= heap_base && p < last_region_end;
557 }
558
559 inline bool ShenandoahHeap::is_in_active_generation(oop obj) const {
560 if (!mode()->is_generational()) {
561 // everything is the same single generation
562 return true;
563 }
564
565 if (active_generation() == nullptr) {
566 // no collection is happening, only expect this to be called
567 // when concurrent processing is active, but that could change
568 return false;
569 }
570
571 assert(is_in(obj), "only check if is in active generation for objects (" PTR_FORMAT ") in heap", p2i(obj));
572 assert((active_generation() == (ShenandoahGeneration*) old_generation()) ||
573 (active_generation() == (ShenandoahGeneration*) young_generation()) ||
574 (active_generation() == global_generation()), "Active generation must be old, young, or global");
575
576 size_t index = heap_region_containing(obj)->index();
577 switch (_affiliations[index]) {
578 case ShenandoahRegionAffiliation::FREE:
579 // Free regions are in Old, Young, Global
580 return true;
581 case ShenandoahRegionAffiliation::YOUNG_GENERATION:
582 // Young regions are in young_generation and global_generation, not in old_generation
583 return (active_generation() != (ShenandoahGeneration*) old_generation());
584 case ShenandoahRegionAffiliation::OLD_GENERATION:
585 // Old regions are in old_generation and global_generation, not in young_generation
586 return (active_generation() != (ShenandoahGeneration*) young_generation());
587 default:
588 assert(false, "Bad affiliation (%d) for region " SIZE_FORMAT, _affiliations[index], index);
589 return false;
590 }
591 }
592
593 inline bool ShenandoahHeap::is_in_young(const void* p) const {
594 return is_in(p) && (_affiliations[heap_region_index_containing(p)] == ShenandoahRegionAffiliation::YOUNG_GENERATION);
595 }
596
597 inline bool ShenandoahHeap::is_in_old(const void* p) const {
598 return is_in(p) && (_affiliations[heap_region_index_containing(p)] == ShenandoahRegionAffiliation::OLD_GENERATION);
599 }
600
601 inline bool ShenandoahHeap::is_old(oop obj) const {
602 return is_gc_generation_young() && is_in_old(obj);
603 }
604
605 inline ShenandoahRegionAffiliation ShenandoahHeap::region_affiliation(const ShenandoahHeapRegion *r) {
606 return (ShenandoahRegionAffiliation) _affiliations[r->index()];
607 }
608
609 inline void ShenandoahHeap::assert_lock_for_affiliation(ShenandoahRegionAffiliation orig_affiliation,
610 ShenandoahRegionAffiliation new_affiliation) {
611 // A lock is required when changing from FREE to NON-FREE. Though it may be possible to elide the lock when
612 // transitioning from in-use to FREE, the current implementation uses a lock for this transition. A lock is
613 // not required to change from YOUNG to OLD (i.e. when promoting humongous region).
614 //
615 // new_affiliation is: FREE YOUNG OLD
616 // orig_affiliation is: FREE X L L
617 // YOUNG L X
618 // OLD L X X
619 // X means state transition won't happen (so don't care)
620 // L means lock should be held
621 // Blank means no lock required because affiliation visibility will not be required until subsequent safepoint
622 //
623 // Note: during full GC, all transitions between states are possible. During Full GC, we should be in a safepoint.
624
625 if ((orig_affiliation == ShenandoahRegionAffiliation::FREE) || (new_affiliation == ShenandoahRegionAffiliation::FREE)) {
626 extern bool _is_at_shenandoah_safepoint();
627 shenandoah_assert_heaplocked_or_fullgc_safepoint();
628 }
629 }
630
631 inline void ShenandoahHeap::set_affiliation(ShenandoahHeapRegion* r, ShenandoahRegionAffiliation new_affiliation) {
632 #ifdef ASSERT
633 assert_lock_for_affiliation(region_affiliation(r), new_affiliation);
634 #endif
635 _affiliations[r->index()] = (uint8_t) new_affiliation;
636 }
637
638 inline ShenandoahRegionAffiliation ShenandoahHeap::region_affiliation(size_t index) {
639 return (ShenandoahRegionAffiliation) _affiliations[index];
640 }
641
642 inline void ShenandoahHeap::set_affiliation(size_t index, ShenandoahRegionAffiliation new_affiliation) {
643 #ifdef ASSERT
644 assert_lock_for_affiliation(region_affiliation(index), new_affiliation);
645 #endif
646 _affiliations[index] = (uint8_t) new_affiliation;
647 }
648
649 inline bool ShenandoahHeap::requires_marking(const void* entry) const {
650 oop obj = cast_to_oop(entry);
651 return !_marking_context->is_marked_strong(obj);
652 }
653
654 inline bool ShenandoahHeap::in_collection_set(oop p) const {
655 assert(collection_set() != nullptr, "Sanity");
656 return collection_set()->is_in(p);
657 }
658
659 inline bool ShenandoahHeap::in_collection_set_loc(void* p) const {
660 assert(collection_set() != nullptr, "Sanity");
661 return collection_set()->is_in_loc(p);
662 }
663
664 inline bool ShenandoahHeap::is_stable() const {
665 return _gc_state.is_clear();
666 }
667
668 inline bool ShenandoahHeap::is_idle() const {
669 return _gc_state.is_unset(YOUNG_MARKING | OLD_MARKING | EVACUATION | UPDATEREFS);
670 }
671
672 inline bool ShenandoahHeap::is_concurrent_mark_in_progress() const {
673 return _gc_state.is_set(YOUNG_MARKING | OLD_MARKING);
674 }
675
676 inline bool ShenandoahHeap::is_concurrent_young_mark_in_progress() const {
677 return _gc_state.is_set(YOUNG_MARKING);
678 }
679
680 inline bool ShenandoahHeap::is_concurrent_old_mark_in_progress() const {
681 return _gc_state.is_set(OLD_MARKING);
682 }
683
684 inline bool ShenandoahHeap::is_evacuation_in_progress() const {
685 return _gc_state.is_set(EVACUATION);
686 }
687
688 inline bool ShenandoahHeap::is_gc_in_progress_mask(uint mask) const {
689 return _gc_state.is_set(mask);
690 }
691
692 inline bool ShenandoahHeap::is_degenerated_gc_in_progress() const {
693 return _degenerated_gc_in_progress.is_set();
694 }
695
696 inline bool ShenandoahHeap::is_full_gc_in_progress() const {
697 return _full_gc_in_progress.is_set();
698 }
699
700 inline bool ShenandoahHeap::is_full_gc_move_in_progress() const {
701 return _full_gc_move_in_progress.is_set();
702 }
703
704 inline bool ShenandoahHeap::is_update_refs_in_progress() const {
705 return _gc_state.is_set(UPDATEREFS);
706 }
707
708 inline bool ShenandoahHeap::is_stw_gc_in_progress() const {
709 return is_full_gc_in_progress() || is_degenerated_gc_in_progress();
710 }
711
712 inline bool ShenandoahHeap::is_concurrent_strong_root_in_progress() const {
713 return _concurrent_strong_root_in_progress.is_set();
714 }
715
716 inline bool ShenandoahHeap::is_concurrent_weak_root_in_progress() const {
717 return _gc_state.is_set(WEAK_ROOTS);
718 }
719
720 inline bool ShenandoahHeap::is_aging_cycle() const {
721 return _is_aging_cycle.is_set();
722 }
723
724 inline bool ShenandoahHeap::is_prepare_for_old_mark_in_progress() const {
725 return _prepare_for_old_mark;
726 }
727
728 inline size_t ShenandoahHeap::set_promoted_reserve(size_t new_val) {
729 size_t orig = _promoted_reserve;
730 _promoted_reserve = new_val;
731 return orig;
732 }
733
734 inline size_t ShenandoahHeap::get_promoted_reserve() const {
735 return _promoted_reserve;
736 }
737
738 // returns previous value
739 size_t ShenandoahHeap::capture_old_usage(size_t old_usage) {
740 size_t previous_value = _captured_old_usage;
741 _captured_old_usage = old_usage;
742 return previous_value;
743 }
744
745 void ShenandoahHeap::set_previous_promotion(size_t promoted_bytes) {
746 shenandoah_assert_heaplocked();
747 _previous_promotion = promoted_bytes;
748 }
749
750 size_t ShenandoahHeap::get_previous_promotion() const {
751 return _previous_promotion;
752 }
753
754 inline size_t ShenandoahHeap::set_old_evac_reserve(size_t new_val) {
755 size_t orig = _old_evac_reserve;
756 _old_evac_reserve = new_val;
757 return orig;
758 }
759
760 inline size_t ShenandoahHeap::get_old_evac_reserve() const {
761 return _old_evac_reserve;
762 }
763
764 inline void ShenandoahHeap::reset_old_evac_expended() {
765 Atomic::store(&_old_evac_expended, (size_t) 0);
766 }
767
768 inline size_t ShenandoahHeap::expend_old_evac(size_t increment) {
769 return Atomic::add(&_old_evac_expended, increment);
770 }
771
772 inline size_t ShenandoahHeap::get_old_evac_expended() {
773 return Atomic::load(&_old_evac_expended);
774 }
775
776 inline void ShenandoahHeap::reset_promoted_expended() {
777 Atomic::store(&_promoted_expended, (size_t) 0);
778 }
779
780 inline size_t ShenandoahHeap::expend_promoted(size_t increment) {
781 return Atomic::add(&_promoted_expended, increment);
782 }
783
784 inline size_t ShenandoahHeap::unexpend_promoted(size_t decrement) {
785 return Atomic::sub(&_promoted_expended, decrement);
786 }
787
788 inline size_t ShenandoahHeap::get_promoted_expended() {
789 return Atomic::load(&_promoted_expended);
790 }
791
792 inline size_t ShenandoahHeap::set_young_evac_reserve(size_t new_val) {
793 size_t orig = _young_evac_reserve;
794 _young_evac_reserve = new_val;
795 return orig;
796 }
797
798 inline size_t ShenandoahHeap::get_young_evac_reserve() const {
799 return _young_evac_reserve;
800 }
801
802 inline intptr_t ShenandoahHeap::set_alloc_supplement_reserve(intptr_t new_val) {
803 intptr_t orig = _alloc_supplement_reserve;
804 _alloc_supplement_reserve = new_val;
805 return orig;
806 }
807
808 inline intptr_t ShenandoahHeap::get_alloc_supplement_reserve() const {
809 return _alloc_supplement_reserve;
810 }
811
812 template<class T>
813 inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl) {
814 marked_object_iterate(region, cl, region->top());
815 }
816
817 template<class T>
818 inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit) {
819 assert(! region->is_humongous_continuation(), "no humongous continuation regions here");
820
821 ShenandoahMarkingContext* const ctx = marking_context();
822
823 HeapWord* tams = ctx->top_at_mark_start(region);
824
825 size_t skip_bitmap_delta = 1;
826 HeapWord* start = region->bottom();
827 HeapWord* end = MIN2(tams, region->end());
828
829 // Step 1. Scan below the TAMS based on bitmap data.
830 HeapWord* limit_bitmap = MIN2(limit, tams);
831
832 // Try to scan the initial candidate. If the candidate is above the TAMS, it would
833 // fail the subsequent "< limit_bitmap" checks, and fall through to Step 2.
834 HeapWord* cb = ctx->get_next_marked_addr(start, end);
835
836 intx dist = ShenandoahMarkScanPrefetch;
837 if (dist > 0) {
838 // Batched scan that prefetches the oop data, anticipating the access to
839 // either header, oop field, or forwarding pointer. Not that we cannot
840 // touch anything in oop, while it still being prefetched to get enough
841 // time for prefetch to work. This is why we try to scan the bitmap linearly,
842 // disregarding the object size. However, since we know forwarding pointer
843 // precedes the object, we can skip over it. Once we cannot trust the bitmap,
844 // there is no point for prefetching the oop contents, as oop->size() will
845 // touch it prematurely.
846
847 // No variable-length arrays in standard C++, have enough slots to fit
848 // the prefetch distance.
849 static const int SLOT_COUNT = 256;
850 guarantee(dist <= SLOT_COUNT, "adjust slot count");
851 HeapWord* slots[SLOT_COUNT];
852
853 int avail;
854 do {
855 avail = 0;
856 for (int c = 0; (c < dist) && (cb < limit_bitmap); c++) {
857 Prefetch::read(cb, oopDesc::mark_offset_in_bytes());
858 slots[avail++] = cb;
859 cb += skip_bitmap_delta;
860 if (cb < limit_bitmap) {
861 cb = ctx->get_next_marked_addr(cb, limit_bitmap);
862 }
863 }
864
865 for (int c = 0; c < avail; c++) {
866 assert (slots[c] < tams, "only objects below TAMS here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(slots[c]), p2i(tams));
867 assert (slots[c] < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(slots[c]), p2i(limit));
868 oop obj = cast_to_oop(slots[c]);
869 assert(oopDesc::is_oop(obj), "sanity");
870 assert(ctx->is_marked(obj), "object expected to be marked");
871 cl->do_object(obj);
872 }
873 } while (avail > 0);
874 } else {
875 while (cb < limit_bitmap) {
876 assert (cb < tams, "only objects below TAMS here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cb), p2i(tams));
877 assert (cb < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cb), p2i(limit));
878 oop obj = cast_to_oop(cb);
879 assert(oopDesc::is_oop(obj), "sanity");
880 assert(ctx->is_marked(obj), "object expected to be marked");
881 cl->do_object(obj);
882 cb += skip_bitmap_delta;
883 if (cb < limit_bitmap) {
884 cb = ctx->get_next_marked_addr(cb, limit_bitmap);
885 }
886 }
887 }
888
889 // Step 2. Accurate size-based traversal, happens past the TAMS.
890 // This restarts the scan at TAMS, which makes sure we traverse all objects,
891 // regardless of what happened at Step 1.
892 HeapWord* cs = tams;
893 while (cs < limit) {
894 assert (cs >= tams, "only objects past TAMS here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cs), p2i(tams));
895 assert (cs < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cs), p2i(limit));
896 oop obj = cast_to_oop(cs);
897 assert(oopDesc::is_oop(obj), "sanity");
898 assert(ctx->is_marked(obj), "object expected to be marked");
899 size_t size = obj->size();
900 cl->do_object(obj);
901 cs += size;
902 }
903 }
904
905 template <class T>
906 class ShenandoahObjectToOopClosure : public ObjectClosure {
907 T* _cl;
908 public:
909 ShenandoahObjectToOopClosure(T* cl) : _cl(cl) {}
910
911 void do_object(oop obj) {
912 obj->oop_iterate(_cl);
913 }
914 };
915
916 template <class T>
917 class ShenandoahObjectToOopBoundedClosure : public ObjectClosure {
918 T* _cl;
919 MemRegion _bounds;
920 public:
921 ShenandoahObjectToOopBoundedClosure(T* cl, HeapWord* bottom, HeapWord* top) :
922 _cl(cl), _bounds(bottom, top) {}
923
924 void do_object(oop obj) {
925 obj->oop_iterate(_cl, _bounds);
926 }
927 };
928
929 template<class T>
930 inline void ShenandoahHeap::marked_object_oop_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* top) {
931 if (region->is_humongous()) {
932 HeapWord* bottom = region->bottom();
933 if (top > bottom) {
934 region = region->humongous_start_region();
935 ShenandoahObjectToOopBoundedClosure<T> objs(cl, bottom, top);
936 marked_object_iterate(region, &objs);
937 }
938 } else {
939 ShenandoahObjectToOopClosure<T> objs(cl);
940 marked_object_iterate(region, &objs, top);
941 }
942 }
943
944 inline ShenandoahHeapRegion* const ShenandoahHeap::get_region(size_t region_idx) const {
945 if (region_idx < _num_regions) {
946 return _regions[region_idx];
947 } else {
948 return nullptr;
949 }
950 }
951
952 inline ShenandoahMarkingContext* ShenandoahHeap::complete_marking_context() const {
953 assert (_marking_context->is_complete()," sanity");
954 return _marking_context;
955 }
956
957 inline ShenandoahMarkingContext* ShenandoahHeap::marking_context() const {
958 return _marking_context;
959 }
960
961 inline void ShenandoahHeap::clear_cards_for(ShenandoahHeapRegion* region) {
962 if (mode()->is_generational()) {
963 _card_scan->mark_range_as_empty(region->bottom(), pointer_delta(region->end(), region->bottom()));
964 }
965 }
966
967 inline void ShenandoahHeap::dirty_cards(HeapWord* start, HeapWord* end) {
968 assert(mode()->is_generational(), "Should only be used for generational mode");
969 size_t words = pointer_delta(end, start);
970 _card_scan->mark_range_as_dirty(start, words);
971 }
972
973 inline void ShenandoahHeap::clear_cards(HeapWord* start, HeapWord* end) {
974 assert(mode()->is_generational(), "Should only be used for generational mode");
975 size_t words = pointer_delta(end, start);
976 _card_scan->mark_range_as_clean(start, words);
977 }
978
979 inline void ShenandoahHeap::mark_card_as_dirty(void* location) {
980 if (mode()->is_generational()) {
981 _card_scan->mark_card_as_dirty((HeapWord*)location);
982 }
983 }
984
985 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP