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.
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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/suspendibleThreadSet.hpp"
34 #include "gc/shared/tlab_globals.hpp"
35 #include "gc/shenandoah/shenandoahAsserts.hpp"
36 #include "gc/shenandoah/shenandoahBarrierSet.inline.hpp"
37 #include "gc/shenandoah/shenandoahCollectionSet.inline.hpp"
38 #include "gc/shenandoah/shenandoahForwarding.inline.hpp"
39 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
40 #include "gc/shenandoah/shenandoahHeapRegionSet.inline.hpp"
41 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
42 #include "gc/shenandoah/shenandoahControlThread.hpp"
43 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
44 #include "gc/shenandoah/shenandoahScanRemembered.inline.hpp"
45 #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
46 #include "gc/shenandoah/shenandoahScanRemembered.inline.hpp"
47 #include "gc/shenandoah/mode/shenandoahMode.hpp"
48 #include "oops/compressedOops.inline.hpp"
49 #include "oops/oop.inline.hpp"
50 #include "runtime/atomic.hpp"
51 #include "runtime/prefetch.inline.hpp"
52 #include "runtime/thread.hpp"
53 #include "utilities/copy.hpp"
54 #include "utilities/globalDefinitions.hpp"
55
56 inline ShenandoahHeap* ShenandoahHeap::heap() {
57 return named_heap<ShenandoahHeap>(CollectedHeap::Shenandoah);
58 }
59
60 inline ShenandoahHeapRegion* ShenandoahRegionIterator::next() {
61 size_t new_index = Atomic::add(&_index, (size_t) 1, memory_order_relaxed);
62 // get_region() provides the bounds-check and returns NULL on OOB.
63 return _heap->get_region(new_index - 1);
64 }
65
66 inline bool ShenandoahHeap::has_forwarded_objects() const {
67 return _gc_state.is_set(HAS_FORWARDED);
68 }
69
70 inline WorkerThreads* ShenandoahHeap::workers() const {
71 return _workers;
72 }
73
74 inline WorkerThreads* ShenandoahHeap::safepoint_workers() {
75 return _safepoint_workers;
76 }
77
78 inline size_t ShenandoahHeap::heap_region_index_containing(const void* addr) const {
79 uintptr_t region_start = ((uintptr_t) addr);
80 uintptr_t index = (region_start - (uintptr_t) base()) >> ShenandoahHeapRegion::region_size_bytes_shift();
81 assert(index < num_regions(), "Region index is in bounds: " PTR_FORMAT, p2i(addr));
82 return index;
83 }
84
85 inline ShenandoahHeapRegion* const ShenandoahHeap::heap_region_containing(const void* addr) const {
86 size_t index = heap_region_index_containing(addr);
87 ShenandoahHeapRegion* const result = get_region(index);
88 assert(addr >= result->bottom() && addr < result->end(), "Heap region contains the address: " PTR_FORMAT, p2i(addr));
89 return result;
90 }
91
92 inline void ShenandoahHeap::enter_evacuation(Thread* t) {
93 _oom_evac_handler.enter_evacuation(t);
94 }
95
96 inline void ShenandoahHeap::leave_evacuation(Thread* t) {
97 _oom_evac_handler.leave_evacuation(t);
98 }
99
100 template <class T>
101 inline void ShenandoahHeap::update_with_forwarded(T* p) {
102 T o = RawAccess<>::oop_load(p);
103 if (!CompressedOops::is_null(o)) {
104 oop obj = CompressedOops::decode_not_null(o);
105 if (in_collection_set(obj)) {
106 // Corner case: when evacuation fails, there are objects in collection
107 // set that are not really forwarded. We can still go and try and update them
108 // (uselessly) to simplify the common path.
109 shenandoah_assert_forwarded_except(p, obj, cancelled_gc());
110 oop fwd = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
111 shenandoah_assert_not_in_cset_except(p, fwd, cancelled_gc());
112
113 // Unconditionally store the update: no concurrent updates expected.
114 RawAccess<IS_NOT_NULL>::oop_store(p, fwd);
115 }
116 }
117 }
118
119 template <class T>
120 inline void ShenandoahHeap::conc_update_with_forwarded(T* p) {
121 T o = RawAccess<>::oop_load(p);
122 if (!CompressedOops::is_null(o)) {
123 oop obj = CompressedOops::decode_not_null(o);
124 if (in_collection_set(obj)) {
125 // Corner case: when evacuation fails, there are objects in collection
126 // set that are not really forwarded. We can still go and try CAS-update them
127 // (uselessly) to simplify the common path.
128 shenandoah_assert_forwarded_except(p, obj, cancelled_gc());
129 oop fwd = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
130 shenandoah_assert_not_in_cset_except(p, fwd, cancelled_gc());
131
132 // Sanity check: we should not be updating the cset regions themselves,
133 // unless we are recovering from the evacuation failure.
134 shenandoah_assert_not_in_cset_loc_except(p, !is_in(p) || cancelled_gc());
135
136 // Either we succeed in updating the reference, or something else gets in our way.
137 // We don't care if that is another concurrent GC update, or another mutator update.
138 atomic_update_oop(fwd, p, obj);
139 }
140 }
141 }
142
143 // Atomic updates of heap location. This is only expected to work with updating the same
144 // logical object with its forwardee. The reason why we need stronger-than-relaxed memory
145 // ordering has to do with coordination with GC barriers and mutator accesses.
146 //
147 // In essence, stronger CAS access is required to maintain the transitive chains that mutator
148 // accesses build by themselves. To illustrate this point, consider the following example.
149 //
150 // Suppose "o" is the object that has a field "x" and the reference to "o" is stored
151 // to field at "addr", which happens to be Java volatile field. Normally, the accesses to volatile
152 // field at "addr" would be matched with release/acquire barriers. This changes when GC moves
153 // the object under mutator feet.
154 //
155 // Thread 1 (Java)
156 // // --- previous access starts here
157 // ...
158 // T1.1: store(&o.x, 1, mo_relaxed)
159 // T1.2: store(&addr, o, mo_release) // volatile store
160 //
161 // // --- new access starts here
162 // // LRB: copy and install the new copy to fwdptr
163 // T1.3: var copy = copy(o)
164 // T1.4: cas(&fwd, t, copy, mo_release) // pointer-mediated publication
165 // <access continues>
166 //
167 // Thread 2 (GC updater)
168 // T2.1: var f = load(&fwd, mo_{consume|acquire}) // pointer-mediated acquisition
169 // T2.2: cas(&addr, o, f, mo_release) // this method
170 //
171 // Thread 3 (Java)
172 // T3.1: var o = load(&addr, mo_acquire) // volatile read
173 // T3.2: if (o != null)
174 // T3.3: var r = load(&o.x, mo_relaxed)
175 //
176 // r is guaranteed to contain "1".
177 //
178 // Without GC involvement, there is synchronizes-with edge from T1.2 to T3.1,
179 // which guarantees this. With GC involvement, when LRB copies the object and
180 // another thread updates the reference to it, we need to have the transitive edge
181 // from T1.4 to T2.1 (that one is guaranteed by forwarding accesses), plus the edge
182 // from T2.2 to T3.1 (which is brought by this CAS).
183 //
184 // Note that we do not need to "acquire" in these methods, because we do not read the
185 // failure witnesses contents on any path, and "release" is enough.
186 //
187
188 inline void ShenandoahHeap::atomic_update_oop(oop update, oop* addr, oop compare) {
189 assert(is_aligned(addr, HeapWordSize), "Address should be aligned: " PTR_FORMAT, p2i(addr));
190 Atomic::cmpxchg(addr, compare, update, memory_order_release);
191 }
192
193 inline void ShenandoahHeap::atomic_update_oop(oop update, narrowOop* addr, narrowOop compare) {
194 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
195 narrowOop u = CompressedOops::encode(update);
196 Atomic::cmpxchg(addr, compare, u, memory_order_release);
197 }
198
199 inline void ShenandoahHeap::atomic_update_oop(oop update, narrowOop* addr, oop compare) {
200 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
201 narrowOop c = CompressedOops::encode(compare);
202 narrowOop u = CompressedOops::encode(update);
203 Atomic::cmpxchg(addr, c, u, memory_order_release);
204 }
205
206 inline bool ShenandoahHeap::atomic_update_oop_check(oop update, oop* addr, oop compare) {
207 assert(is_aligned(addr, HeapWordSize), "Address should be aligned: " PTR_FORMAT, p2i(addr));
208 return (oop) Atomic::cmpxchg(addr, compare, update, memory_order_release) == compare;
209 }
210
211 inline bool ShenandoahHeap::atomic_update_oop_check(oop update, narrowOop* addr, narrowOop compare) {
212 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
213 narrowOop u = CompressedOops::encode(update);
214 return (narrowOop) Atomic::cmpxchg(addr, compare, u, memory_order_release) == compare;
215 }
216
217 inline bool ShenandoahHeap::atomic_update_oop_check(oop update, narrowOop* addr, oop compare) {
218 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
219 narrowOop c = CompressedOops::encode(compare);
220 narrowOop u = CompressedOops::encode(update);
221 return CompressedOops::decode(Atomic::cmpxchg(addr, c, u, memory_order_release)) == compare;
222 }
223
224 // The memory ordering discussion above does not apply for methods that store NULLs:
225 // then, there is no transitive reads in mutator (as we see NULLs), and we can do
226 // relaxed memory ordering there.
227
228 inline void ShenandoahHeap::atomic_clear_oop(oop* addr, oop compare) {
229 assert(is_aligned(addr, HeapWordSize), "Address should be aligned: " PTR_FORMAT, p2i(addr));
230 Atomic::cmpxchg(addr, compare, oop(), memory_order_relaxed);
231 }
232
233 inline void ShenandoahHeap::atomic_clear_oop(narrowOop* addr, oop compare) {
234 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
235 narrowOop cmp = CompressedOops::encode(compare);
236 Atomic::cmpxchg(addr, cmp, narrowOop(), memory_order_relaxed);
237 }
238
239 inline void ShenandoahHeap::atomic_clear_oop(narrowOop* addr, narrowOop compare) {
240 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
241 Atomic::cmpxchg(addr, compare, narrowOop(), memory_order_relaxed);
242 }
243
244 inline bool ShenandoahHeap::cancelled_gc() const {
245 return _cancelled_gc.get() == CANCELLED;
246 }
247
248 inline bool ShenandoahHeap::check_cancelled_gc_and_yield(bool sts_active) {
249 if (! (sts_active && ShenandoahSuspendibleWorkers)) {
250 return cancelled_gc();
251 }
252
253 jbyte prev = _cancelled_gc.cmpxchg(NOT_CANCELLED, CANCELLABLE);
254 if (prev == CANCELLABLE || prev == NOT_CANCELLED) {
255 if (SuspendibleThreadSet::should_yield()) {
256 SuspendibleThreadSet::yield();
257 }
258
259 // Back to CANCELLABLE. The thread that poked NOT_CANCELLED first gets
260 // to restore to CANCELLABLE.
261 if (prev == CANCELLABLE) {
262 _cancelled_gc.set(CANCELLABLE);
263 }
264 return false;
265 } else {
266 return true;
267 }
268 }
269
270 inline void ShenandoahHeap::clear_cancelled_gc(bool clear_oom_handler) {
271 _cancelled_gc.set(CANCELLABLE);
272 if (_cancel_requested_time > 0) {
273 double cancel_time = os::elapsedTime() - _cancel_requested_time;
274 log_info(gc)("GC cancellation took %.3fs", cancel_time);
275 _cancel_requested_time = 0;
276 }
277
278 if (clear_oom_handler) {
279 _oom_evac_handler.clear();
280 }
281 }
282
283 inline HeapWord* ShenandoahHeap::allocate_from_gclab(Thread* thread, size_t size) {
284 assert(UseTLAB, "TLABs should be enabled");
285
286 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
287 if (gclab == NULL) {
288 assert(!thread->is_Java_thread() && !thread->is_Worker_thread(),
289 "Performance: thread should have GCLAB: %s", thread->name());
290 // No GCLABs in this thread, fallback to shared allocation
291 return NULL;
292 }
293 HeapWord* obj = gclab->allocate(size);
294 if (obj != NULL) {
295 return obj;
296 }
297 return allocate_from_gclab_slow(thread, size);
298 }
299
300 inline HeapWord* ShenandoahHeap::allocate_from_plab(Thread* thread, size_t size, bool is_promotion) {
301 assert(UseTLAB, "TLABs should be enabled");
302
303 PLAB* plab = ShenandoahThreadLocalData::plab(thread);
304 if (is_promotion && !ShenandoahThreadLocalData::allow_plab_promotions(thread)) {
305 return NULL;
306 } else if (plab == NULL) {
307 assert(!thread->is_Java_thread() && !thread->is_Worker_thread(),
308 "Performance: thread should have PLAB: %s", thread->name());
309 // No PLABs in this thread, fallback to shared allocation
310 return NULL;
311 }
312 HeapWord* obj = plab->allocate(size);
313 if (obj == NULL) {
314 obj = allocate_from_plab_slow(thread, size, is_promotion);
315 }
316 if (is_promotion) {
317 ShenandoahThreadLocalData::add_to_plab_promoted(thread, size * HeapWordSize);
318 } else {
319 ShenandoahThreadLocalData::add_to_plab_evacuated(thread, size * HeapWordSize);
320 }
321 return obj;
322 }
323
324 inline oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) {
325 assert(thread == Thread::current(), "Expected thread parameter to be current thread.");
326 if (ShenandoahThreadLocalData::is_oom_during_evac(thread)) {
327 // This thread went through the OOM during evac protocol and it is safe to return
328 // the forward pointer. It must not attempt to evacuate any more.
329 return ShenandoahBarrierSet::resolve_forwarded(p);
330 }
331
332 assert(ShenandoahThreadLocalData::is_evac_allowed(thread), "must be enclosed in oom-evac scope");
333
334 ShenandoahHeapRegion* r = heap_region_containing(p);
335 assert(!r->is_humongous(), "never evacuate humongous objects");
336
337 ShenandoahRegionAffiliation target_gen = r->affiliation();
338 if (mode()->is_generational() && ShenandoahHeap::heap()->is_gc_generation_young() &&
339 target_gen == YOUNG_GENERATION && ShenandoahPromoteTenuredObjects) {
340 markWord mark = p->mark();
341 if (mark.is_marked()) {
342 // Already forwarded.
343 return ShenandoahBarrierSet::resolve_forwarded(p);
344 }
345 if (mark.has_displaced_mark_helper()) {
346 // We don't want to deal with MT here just to ensure we read the right mark word.
347 // Skip the potential promotion attempt for this one.
348 } else if (r->age() + mark.age() >= InitialTenuringThreshold) {
349 oop result = try_evacuate_object(p, thread, r, OLD_GENERATION);
350 if (result != NULL) {
351 return result;
352 }
353 // If we failed to promote this aged object, we'll fall through to code below and evacuat to young-gen.
354 }
355 }
356 return try_evacuate_object(p, thread, r, target_gen);
357 }
358
359 // try_evacuate_object registers the object and dirties the associated remembered set information when evacuating
360 // to OLD_GENERATION.
361 inline oop ShenandoahHeap::try_evacuate_object(oop p, Thread* thread, ShenandoahHeapRegion* from_region,
362 ShenandoahRegionAffiliation target_gen) {
363 bool alloc_from_lab = true;
364 HeapWord* copy = NULL;
365 size_t size = p->size();
366 bool is_promotion = (target_gen == OLD_GENERATION) && from_region->is_young();
367
368 #ifdef ASSERT
369 if (ShenandoahOOMDuringEvacALot &&
370 (os::random() & 1) == 0) { // Simulate OOM every ~2nd slow-path call
371 copy = NULL;
372 } else {
373 #endif
374 if (UseTLAB) {
375 switch (target_gen) {
376 case YOUNG_GENERATION: {
377 copy = allocate_from_gclab(thread, size);
378 if ((copy == nullptr) && (size < ShenandoahThreadLocalData::gclab_size(thread))) {
379 // GCLAB allocation failed because we are bumping up against the limit on young evacuation reserve. Try resetting
380 // the desired GCLAB size and retry GCLAB allocation to avoid cascading of shared memory allocations.
381 ShenandoahThreadLocalData::set_gclab_size(thread, PLAB::min_size());
382 copy = allocate_from_gclab(thread, size);
383 // If we still get nullptr, we'll try a shared allocation below.
384 }
385 break;
386 }
387 case OLD_GENERATION: {
388 if (ShenandoahUsePLAB) {
389 copy = allocate_from_plab(thread, size, is_promotion);
390 if ((copy == nullptr) && (size < ShenandoahThreadLocalData::plab_size(thread))) {
391 // PLAB allocation failed because we are bumping up against the limit on old evacuation reserve. Try resetting
392 // the desired PLAB size and retry PLAB allocation to avoid cascading of shared memory allocations.
393 ShenandoahThreadLocalData::set_plab_size(thread, PLAB::min_size());
394 copy = allocate_from_plab(thread, size, is_promotion);
395 // If we still get nullptr, we'll try a shared allocation below.
396 }
397 }
398 break;
399 }
400 default: {
401 ShouldNotReachHere();
402 break;
403 }
404 }
405 }
406
407 if (copy == NULL) {
408 // If we failed to allocated in LAB, we'll try a shared allocation.
409 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared_gc(size, target_gen);
410 copy = allocate_memory(req, is_promotion);
411 alloc_from_lab = false;
412 }
413 #ifdef ASSERT
414 }
415 #endif
416
417 if (copy == NULL) {
418 if (target_gen == OLD_GENERATION) {
419 assert(mode()->is_generational(), "Should only be here in generational mode.");
420 if (from_region->is_young()) {
421 // Signal that promotion failed. Will evacuate this old object somewhere in young gen.
422 handle_promotion_failure();
423 return NULL;
424 } else {
425 // Remember that evacuation to old gen failed. We'll want to trigger a full gc to recover from this
426 // after the evacuation threads have finished.
427 handle_old_evacuation_failure();
428 }
429 }
430
431 control_thread()->handle_alloc_failure_evac(size);
432
433 _oom_evac_handler.handle_out_of_memory_during_evacuation();
434
435 return ShenandoahBarrierSet::resolve_forwarded(p);
436 }
437
438 // Copy the object:
439 Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(p), copy, size);
440
441 oop copy_val = cast_to_oop(copy);
442
443 if (mode()->is_generational() && target_gen == YOUNG_GENERATION && is_aging_cycle()) {
444 ShenandoahHeap::increase_object_age(copy_val, from_region->age() + 1);
445 }
446
447 // Try to install the new forwarding pointer.
448 oop result = ShenandoahForwarding::try_update_forwardee(p, copy_val);
449 if (result == copy_val) {
450 // Successfully evacuated. Our copy is now the public one!
451 if (mode()->is_generational() && target_gen == OLD_GENERATION) {
452 handle_old_evacuation(copy, size, from_region->is_young());
453 }
454 shenandoah_assert_correct(NULL, copy_val);
455 return copy_val;
456 } else {
457 // Failed to evacuate. We need to deal with the object that is left behind. Since this
458 // new allocation is certainly after TAMS, it will be considered live in the next cycle.
459 // But if it happens to contain references to evacuated regions, those references would
460 // not get updated for this stale copy during this cycle, and we will crash while scanning
461 // it the next cycle.
462 if (alloc_from_lab) {
463 // For LAB allocations, it is enough to rollback the allocation ptr. Either the next
464 // object will overwrite this stale copy, or the filler object on LAB retirement will
465 // do this.
466 switch (target_gen) {
467 case YOUNG_GENERATION: {
468 ShenandoahThreadLocalData::gclab(thread)->undo_allocation(copy, size);
469 break;
470 }
471 case OLD_GENERATION: {
472 ShenandoahThreadLocalData::plab(thread)->undo_allocation(copy, size);
473 if (is_promotion) {
474 ShenandoahThreadLocalData::subtract_from_plab_promoted(thread, size * HeapWordSize);
475 } else {
476 ShenandoahThreadLocalData::subtract_from_plab_evacuated(thread, size * HeapWordSize);
477 }
478 break;
479 }
480 default: {
481 ShouldNotReachHere();
482 break;
483 }
484 }
485 } else {
486 // For non-LAB allocations, we have no way to retract the allocation, and
487 // have to explicitly overwrite the copy with the filler object. With that overwrite,
488 // we have to keep the fwdptr initialized and pointing to our (stale) copy.
489 fill_with_object(copy, size);
490 shenandoah_assert_correct(NULL, copy_val);
491 // For non-LAB allocations, the object has already been registered
492 }
493 shenandoah_assert_correct(NULL, result);
494 return result;
495 }
496 }
497
498 void ShenandoahHeap::increase_object_age(oop obj, uint additional_age) {
499 markWord w = obj->has_displaced_mark() ? obj->displaced_mark() : obj->mark();
500 w = w.set_age(MIN2(markWord::max_age, w.age() + additional_age));
501 if (obj->has_displaced_mark()) {
502 obj->set_displaced_mark(w);
503 } else {
504 obj->set_mark(w);
505 }
506 }
507
508 inline bool ShenandoahHeap::clear_old_evacuation_failure() {
509 return _old_gen_oom_evac.try_unset();
510 }
511
512 inline bool ShenandoahHeap::is_old(oop obj) const {
513 return is_gc_generation_young() && is_in_old(obj);
514 }
515
516 inline bool ShenandoahHeap::requires_marking(const void* entry) const {
517 oop obj = cast_to_oop(entry);
518 return !_marking_context->is_marked_strong(obj);
519 }
520
521 inline bool ShenandoahHeap::in_collection_set(oop p) const {
522 assert(collection_set() != NULL, "Sanity");
523 return collection_set()->is_in(p);
524 }
525
526 inline bool ShenandoahHeap::in_collection_set_loc(void* p) const {
527 assert(collection_set() != NULL, "Sanity");
528 return collection_set()->is_in_loc(p);
529 }
530
531 inline bool ShenandoahHeap::is_stable() const {
532 return _gc_state.is_clear();
533 }
534
535 inline bool ShenandoahHeap::is_idle() const {
536 return _gc_state.is_unset(YOUNG_MARKING | OLD_MARKING | EVACUATION | UPDATEREFS);
537 }
538
539 inline bool ShenandoahHeap::is_concurrent_mark_in_progress() const {
540 return _gc_state.is_set(YOUNG_MARKING | OLD_MARKING);
541 }
542
543 inline bool ShenandoahHeap::is_concurrent_young_mark_in_progress() const {
544 return _gc_state.is_set(YOUNG_MARKING);
545 }
546
547 inline bool ShenandoahHeap::is_concurrent_old_mark_in_progress() const {
548 return _gc_state.is_set(OLD_MARKING);
549 }
550
551 inline bool ShenandoahHeap::is_evacuation_in_progress() const {
552 return _gc_state.is_set(EVACUATION);
553 }
554
555 inline bool ShenandoahHeap::is_gc_in_progress_mask(uint mask) const {
556 return _gc_state.is_set(mask);
557 }
558
559 inline bool ShenandoahHeap::is_degenerated_gc_in_progress() const {
560 return _degenerated_gc_in_progress.is_set();
561 }
562
563 inline bool ShenandoahHeap::is_full_gc_in_progress() const {
564 return _full_gc_in_progress.is_set();
565 }
566
567 inline bool ShenandoahHeap::is_full_gc_move_in_progress() const {
568 return _full_gc_move_in_progress.is_set();
569 }
570
571 inline bool ShenandoahHeap::is_update_refs_in_progress() const {
572 return _gc_state.is_set(UPDATEREFS);
573 }
574
575 inline bool ShenandoahHeap::is_stw_gc_in_progress() const {
576 return is_full_gc_in_progress() || is_degenerated_gc_in_progress();
577 }
578
579 inline bool ShenandoahHeap::is_concurrent_strong_root_in_progress() const {
580 return _concurrent_strong_root_in_progress.is_set();
581 }
582
583 inline bool ShenandoahHeap::is_concurrent_weak_root_in_progress() const {
584 return _gc_state.is_set(WEAK_ROOTS);
585 }
586
587 inline bool ShenandoahHeap::is_aging_cycle() const {
588 return _is_aging_cycle.is_set();
589 }
590
591 inline size_t ShenandoahHeap::set_promotion_reserve(size_t new_val) {
592 size_t orig = _promotion_reserve;
593 _promotion_reserve = new_val;
594 return orig;
595 }
596
597 inline size_t ShenandoahHeap::get_promotion_reserve() const {
598 return _promotion_reserve;
599 }
600
601 // returns previous value
602 size_t ShenandoahHeap::capture_old_usage(size_t old_usage) {
603 size_t previous_value = _captured_old_usage;
604 _captured_old_usage = old_usage;
605 return previous_value;
606 }
607
608 void ShenandoahHeap::set_previous_promotion(size_t promoted_bytes) {
609 _previous_promotion = promoted_bytes;
610 }
611
612 size_t ShenandoahHeap::get_previous_promotion() const {
613 return _previous_promotion;
614 }
615
616 inline size_t ShenandoahHeap::set_old_evac_reserve(size_t new_val) {
617 size_t orig = _old_evac_reserve;
618 _old_evac_reserve = new_val;
619 return orig;
620 }
621
622 inline size_t ShenandoahHeap::get_old_evac_reserve() const {
623 return _old_evac_reserve;
624 }
625
626 inline void ShenandoahHeap::reset_old_evac_expended() {
627 _old_evac_expended = 0;
628 }
629
630 inline size_t ShenandoahHeap::expend_old_evac(size_t increment) {
631 _old_evac_expended += increment;
632 return _old_evac_expended;
633 }
634
635 inline size_t ShenandoahHeap::get_old_evac_expended() const {
636 return _old_evac_expended;
637 }
638
639 inline size_t ShenandoahHeap::set_young_evac_reserve(size_t new_val) {
640 size_t orig = _young_evac_reserve;
641 _young_evac_reserve = new_val;
642 return orig;
643 }
644
645 inline size_t ShenandoahHeap::get_young_evac_reserve() const {
646 return _young_evac_reserve;
647 }
648
649 inline intptr_t ShenandoahHeap::set_alloc_supplement_reserve(intptr_t new_val) {
650 intptr_t orig = _alloc_supplement_reserve;
651 _alloc_supplement_reserve = new_val;
652 return orig;
653 }
654
655 inline intptr_t ShenandoahHeap::get_alloc_supplement_reserve() const {
656 return _alloc_supplement_reserve;
657 }
658
659 template<class T>
660 inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl) {
661 marked_object_iterate(region, cl, region->top());
662 }
663
664 template<class T>
665 inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit) {
666 assert(! region->is_humongous_continuation(), "no humongous continuation regions here");
667
668 ShenandoahMarkingContext* const ctx = marking_context();
669
670 HeapWord* tams = ctx->top_at_mark_start(region);
671
672 size_t skip_bitmap_delta = 1;
673 HeapWord* start = region->bottom();
674 HeapWord* end = MIN2(tams, region->end());
675
676 // Step 1. Scan below the TAMS based on bitmap data.
677 HeapWord* limit_bitmap = MIN2(limit, tams);
678
679 // Try to scan the initial candidate. If the candidate is above the TAMS, it would
680 // fail the subsequent "< limit_bitmap" checks, and fall through to Step 2.
681 HeapWord* cb = ctx->get_next_marked_addr(start, end);
682
683 intx dist = ShenandoahMarkScanPrefetch;
684 if (dist > 0) {
685 // Batched scan that prefetches the oop data, anticipating the access to
686 // either header, oop field, or forwarding pointer. Not that we cannot
687 // touch anything in oop, while it still being prefetched to get enough
688 // time for prefetch to work. This is why we try to scan the bitmap linearly,
689 // disregarding the object size. However, since we know forwarding pointer
690 // preceeds the object, we can skip over it. Once we cannot trust the bitmap,
691 // there is no point for prefetching the oop contents, as oop->size() will
692 // touch it prematurely.
693
694 // No variable-length arrays in standard C++, have enough slots to fit
695 // the prefetch distance.
696 static const int SLOT_COUNT = 256;
697 guarantee(dist <= SLOT_COUNT, "adjust slot count");
698 HeapWord* slots[SLOT_COUNT];
699
700 int avail;
701 do {
702 avail = 0;
703 for (int c = 0; (c < dist) && (cb < limit_bitmap); c++) {
704 Prefetch::read(cb, oopDesc::mark_offset_in_bytes());
705 slots[avail++] = cb;
706 cb += skip_bitmap_delta;
707 if (cb < limit_bitmap) {
708 cb = ctx->get_next_marked_addr(cb, limit_bitmap);
709 }
710 }
711
712 for (int c = 0; c < avail; c++) {
713 assert (slots[c] < tams, "only objects below TAMS here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(slots[c]), p2i(tams));
714 assert (slots[c] < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(slots[c]), p2i(limit));
715 oop obj = cast_to_oop(slots[c]);
716 assert(oopDesc::is_oop(obj), "sanity");
717 assert(ctx->is_marked(obj), "object expected to be marked");
718 cl->do_object(obj);
719 }
720 } while (avail > 0);
721 } else {
722 while (cb < limit_bitmap) {
723 assert (cb < tams, "only objects below TAMS here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cb), p2i(tams));
724 assert (cb < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cb), p2i(limit));
725 oop obj = cast_to_oop(cb);
726 assert(oopDesc::is_oop(obj), "sanity");
727 assert(ctx->is_marked(obj), "object expected to be marked");
728 cl->do_object(obj);
729 cb += skip_bitmap_delta;
730 if (cb < limit_bitmap) {
731 cb = ctx->get_next_marked_addr(cb, limit_bitmap);
732 }
733 }
734 }
735
736 // Step 2. Accurate size-based traversal, happens past the TAMS.
737 // This restarts the scan at TAMS, which makes sure we traverse all objects,
738 // regardless of what happened at Step 1.
739 HeapWord* cs = tams;
740 while (cs < limit) {
741 assert (cs >= tams, "only objects past TAMS here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cs), p2i(tams));
742 assert (cs < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cs), p2i(limit));
743 oop obj = cast_to_oop(cs);
744 assert(oopDesc::is_oop(obj), "sanity");
745 assert(ctx->is_marked(obj), "object expected to be marked");
746 size_t size = obj->size();
747 cl->do_object(obj);
748 cs += size;
749 }
750 }
751
752 template <class T>
753 class ShenandoahObjectToOopClosure : public ObjectClosure {
754 T* _cl;
755 public:
756 ShenandoahObjectToOopClosure(T* cl) : _cl(cl) {}
757
758 void do_object(oop obj) {
759 obj->oop_iterate(_cl);
760 }
761 };
762
763 template <class T>
764 class ShenandoahObjectToOopBoundedClosure : public ObjectClosure {
765 T* _cl;
766 MemRegion _bounds;
767 public:
768 ShenandoahObjectToOopBoundedClosure(T* cl, HeapWord* bottom, HeapWord* top) :
769 _cl(cl), _bounds(bottom, top) {}
770
771 void do_object(oop obj) {
772 obj->oop_iterate(_cl, _bounds);
773 }
774 };
775
776 template<class T>
777 inline void ShenandoahHeap::marked_object_oop_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* top) {
778 if (region->is_humongous()) {
779 HeapWord* bottom = region->bottom();
780 if (top > bottom) {
781 region = region->humongous_start_region();
782 ShenandoahObjectToOopBoundedClosure<T> objs(cl, bottom, top);
783 marked_object_iterate(region, &objs);
784 }
785 } else {
786 ShenandoahObjectToOopClosure<T> objs(cl);
787 marked_object_iterate(region, &objs, top);
788 }
789 }
790
791 inline ShenandoahHeapRegion* const ShenandoahHeap::get_region(size_t region_idx) const {
792 if (region_idx < _num_regions) {
793 return _regions[region_idx];
794 } else {
795 return NULL;
796 }
797 }
798
799 inline ShenandoahMarkingContext* ShenandoahHeap::complete_marking_context() const {
800 assert (_marking_context->is_complete()," sanity");
801 return _marking_context;
802 }
803
804 inline ShenandoahMarkingContext* ShenandoahHeap::marking_context() const {
805 return _marking_context;
806 }
807
808 inline void ShenandoahHeap::clear_cards_for(ShenandoahHeapRegion* region) {
809 if (mode()->is_generational()) {
810 _card_scan->mark_range_as_empty(region->bottom(), pointer_delta(region->end(), region->bottom()));
811 }
812 }
813
814 inline void ShenandoahHeap::dirty_cards(HeapWord* start, HeapWord* end) {
815 assert(mode()->is_generational(), "Should only be used for generational mode");
816 size_t words = pointer_delta(end, start);
817 _card_scan->mark_range_as_dirty(start, words);
818 }
819
820 inline void ShenandoahHeap::clear_cards(HeapWord* start, HeapWord* end) {
821 assert(mode()->is_generational(), "Should only be used for generational mode");
822 size_t words = pointer_delta(end, start);
823 _card_scan->mark_range_as_clean(start, words);
824 }
825
826 inline void ShenandoahHeap::mark_card_as_dirty(void* location) {
827 if (mode()->is_generational()) {
828 _card_scan->mark_card_as_dirty((HeapWord*)location);
829 }
830 }
831
832 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP