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/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/shenandoahObjectUtils.inline.hpp"
45 #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
46 #include "oops/compressedOops.inline.hpp"
47 #include "oops/oop.inline.hpp"
48 #include "runtime/atomic.hpp"
49 #include "runtime/prefetch.inline.hpp"
50 #include "runtime/thread.hpp"
51 #include "utilities/copy.hpp"
52 #include "utilities/globalDefinitions.hpp"
53
54 inline ShenandoahHeap* ShenandoahHeap::heap() {
55 return named_heap<ShenandoahHeap>(CollectedHeap::Shenandoah);
56 }
57
58 inline ShenandoahHeapRegion* ShenandoahRegionIterator::next() {
59 size_t new_index = Atomic::add(&_index, (size_t) 1, memory_order_relaxed);
60 // get_region() provides the bounds-check and returns NULL on OOB.
61 return _heap->get_region(new_index - 1);
62 }
63
64 inline bool ShenandoahHeap::has_forwarded_objects() const {
65 return _gc_state.is_set(HAS_FORWARDED);
66 }
67
68 inline WorkGang* ShenandoahHeap::workers() const {
69 return _workers;
70 }
71
72 inline WorkGang* ShenandoahHeap::safepoint_workers() {
73 return _safepoint_workers;
74 }
75
76 inline size_t ShenandoahHeap::heap_region_index_containing(const void* addr) const {
77 uintptr_t region_start = ((uintptr_t) addr);
78 uintptr_t index = (region_start - (uintptr_t) base()) >> ShenandoahHeapRegion::region_size_bytes_shift();
79 assert(index < num_regions(), "Region index is in bounds: " PTR_FORMAT, p2i(addr));
80 return index;
81 }
82
83 inline ShenandoahHeapRegion* const ShenandoahHeap::heap_region_containing(const void* addr) const {
84 size_t index = heap_region_index_containing(addr);
85 ShenandoahHeapRegion* const result = get_region(index);
86 assert(addr >= result->bottom() && addr < result->end(), "Heap region contains the address: " PTR_FORMAT, p2i(addr));
87 return result;
88 }
89
90 inline void ShenandoahHeap::enter_evacuation(Thread* t) {
91 _oom_evac_handler.enter_evacuation(t);
92 }
93
94 inline void ShenandoahHeap::leave_evacuation(Thread* t) {
95 _oom_evac_handler.leave_evacuation(t);
96 }
97
98 template <class T>
99 inline void ShenandoahHeap::update_with_forwarded(T* p) {
100 T o = RawAccess<>::oop_load(p);
101 if (!CompressedOops::is_null(o)) {
102 oop obj = CompressedOops::decode_not_null(o);
103 if (in_collection_set(obj)) {
104 // Corner case: when evacuation fails, there are objects in collection
105 // set that are not really forwarded. We can still go and try and update them
106 // (uselessly) to simplify the common path.
107 shenandoah_assert_forwarded_except(p, obj, cancelled_gc());
108 oop fwd = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
109 shenandoah_assert_not_in_cset_except(p, fwd, cancelled_gc());
110
111 // Unconditionally store the update: no concurrent updates expected.
112 RawAccess<IS_NOT_NULL>::oop_store(p, fwd);
113 }
114 }
115 }
116
117 template <class T>
118 inline void ShenandoahHeap::conc_update_with_forwarded(T* p) {
119 T o = RawAccess<>::oop_load(p);
120 if (!CompressedOops::is_null(o)) {
121 oop obj = CompressedOops::decode_not_null(o);
122 if (in_collection_set(obj)) {
123 // Corner case: when evacuation fails, there are objects in collection
124 // set that are not really forwarded. We can still go and try CAS-update them
125 // (uselessly) to simplify the common path.
126 shenandoah_assert_forwarded_except(p, obj, cancelled_gc());
127 oop fwd = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
128 shenandoah_assert_not_in_cset_except(p, fwd, cancelled_gc());
129
130 // Sanity check: we should not be updating the cset regions themselves,
131 // unless we are recovering from the evacuation failure.
132 shenandoah_assert_not_in_cset_loc_except(p, !is_in(p) || cancelled_gc());
133
134 // Either we succeed in updating the reference, or something else gets in our way.
135 // We don't care if that is another concurrent GC update, or another mutator update.
136 // We only check that non-NULL store still updated with non-forwarded reference.
137 oop witness = cas_oop(fwd, p, obj);
138 shenandoah_assert_not_forwarded_except(p, witness, (witness == NULL) || (witness == obj));
139 }
140 }
141 }
142
143 inline oop ShenandoahHeap::cas_oop(oop n, oop* addr, oop c) {
144 assert(is_aligned(addr, HeapWordSize), "Address should be aligned: " PTR_FORMAT, p2i(addr));
145 return (oop) Atomic::cmpxchg(addr, c, n);
146 }
147
148 inline oop ShenandoahHeap::cas_oop(oop n, narrowOop* addr, narrowOop c) {
149 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
150 narrowOop val = CompressedOops::encode(n);
151 return CompressedOops::decode(Atomic::cmpxchg(addr, c, val));
152 }
153
154 inline oop ShenandoahHeap::cas_oop(oop n, narrowOop* addr, oop c) {
155 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
156 narrowOop cmp = CompressedOops::encode(c);
157 narrowOop val = CompressedOops::encode(n);
158 return CompressedOops::decode(Atomic::cmpxchg(addr, cmp, val));
159 }
160
161 inline bool ShenandoahHeap::cancelled_gc() const {
162 return _cancelled_gc.get() == CANCELLED;
163 }
164
165 inline bool ShenandoahHeap::check_cancelled_gc_and_yield(bool sts_active) {
166 if (! (sts_active && ShenandoahSuspendibleWorkers)) {
167 return cancelled_gc();
168 }
169
170 jbyte prev = _cancelled_gc.cmpxchg(NOT_CANCELLED, CANCELLABLE);
171 if (prev == CANCELLABLE || prev == NOT_CANCELLED) {
172 if (SuspendibleThreadSet::should_yield()) {
173 SuspendibleThreadSet::yield();
174 }
175
176 // Back to CANCELLABLE. The thread that poked NOT_CANCELLED first gets
177 // to restore to CANCELLABLE.
178 if (prev == CANCELLABLE) {
179 _cancelled_gc.set(CANCELLABLE);
180 }
181 return false;
182 } else {
183 return true;
184 }
185 }
186
187 inline void ShenandoahHeap::clear_cancelled_gc() {
188 _cancelled_gc.set(CANCELLABLE);
189 _oom_evac_handler.clear();
190 }
191
192 inline HeapWord* ShenandoahHeap::allocate_from_gclab(Thread* thread, size_t size) {
193 assert(UseTLAB, "TLABs should be enabled");
194
195 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
196 if (gclab == NULL) {
197 assert(!thread->is_Java_thread() && !thread->is_Worker_thread(),
198 "Performance: thread should have GCLAB: %s", thread->name());
199 // No GCLABs in this thread, fallback to shared allocation
200 return NULL;
201 }
202 HeapWord* obj = gclab->allocate(size);
203 if (obj != NULL) {
204 return obj;
205 }
206 // Otherwise...
207 return allocate_from_gclab_slow(thread, size);
208 }
209
210 inline oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) {
211 if (ShenandoahThreadLocalData::is_oom_during_evac(Thread::current())) {
212 // This thread went through the OOM during evac protocol and it is safe to return
213 // the forward pointer. It must not attempt to evacuate any more.
214 return ShenandoahBarrierSet::resolve_forwarded(p);
215 }
216
217 assert(ShenandoahThreadLocalData::is_evac_allowed(thread), "must be enclosed in oom-evac scope");
218
219 size_t size = ShenandoahObjectUtils::size(p);
220
221 assert(!heap_region_containing(p)->is_humongous(), "never evacuate humongous objects");
222
223 bool alloc_from_gclab = true;
224 HeapWord* copy = NULL;
225
226 #ifdef ASSERT
227 if (ShenandoahOOMDuringEvacALot &&
228 (os::random() & 1) == 0) { // Simulate OOM every ~2nd slow-path call
229 copy = NULL;
230 } else {
231 #endif
232 if (UseTLAB) {
233 copy = allocate_from_gclab(thread, size);
234 }
235 if (copy == NULL) {
236 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared_gc(size);
237 copy = allocate_memory(req);
238 alloc_from_gclab = false;
239 }
240 #ifdef ASSERT
241 }
242 #endif
243
244 if (copy == NULL) {
245 control_thread()->handle_alloc_failure_evac(size);
246
247 _oom_evac_handler.handle_out_of_memory_during_evacuation();
248
249 return ShenandoahBarrierSet::resolve_forwarded(p);
250 }
251
252 // Copy the object:
253 Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(p), copy, size);
254
255 // Try to install the new forwarding pointer.
256 oop copy_val = cast_to_oop(copy);
257 oop result = ShenandoahForwarding::try_update_forwardee(p, copy_val);
258 if (result == copy_val) {
259 // Successfully evacuated. Our copy is now the public one!
260 shenandoah_assert_correct(NULL, copy_val);
261 return copy_val;
262 } else {
263 // Failed to evacuate. We need to deal with the object that is left behind. Since this
264 // new allocation is certainly after TAMS, it will be considered live in the next cycle.
265 // But if it happens to contain references to evacuated regions, those references would
266 // not get updated for this stale copy during this cycle, and we will crash while scanning
267 // it the next cycle.
268 //
269 // For GCLAB allocations, it is enough to rollback the allocation ptr. Either the next
270 // object will overwrite this stale copy, or the filler object on LAB retirement will
271 // do this. For non-GCLAB allocations, we have no way to retract the allocation, and
272 // have to explicitly overwrite the copy with the filler object. With that overwrite,
273 // we have to keep the fwdptr initialized and pointing to our (stale) copy.
274 if (alloc_from_gclab) {
275 ShenandoahThreadLocalData::gclab(thread)->undo_allocation(copy, size);
276 } else {
277 fill_with_object(copy, size);
278 shenandoah_assert_correct(NULL, copy_val);
279 }
280 shenandoah_assert_correct(NULL, result);
281 return result;
282 }
283 }
284
285 inline bool ShenandoahHeap::requires_marking(const void* entry) const {
286 oop obj = cast_to_oop(entry);
287 return !_marking_context->is_marked_strong(obj);
288 }
289
290 inline bool ShenandoahHeap::in_collection_set(oop p) const {
291 assert(collection_set() != NULL, "Sanity");
292 return collection_set()->is_in(p);
293 }
294
295 inline bool ShenandoahHeap::in_collection_set_loc(void* p) const {
296 assert(collection_set() != NULL, "Sanity");
297 return collection_set()->is_in_loc(p);
298 }
299
300 inline bool ShenandoahHeap::is_stable() const {
301 return _gc_state.is_clear();
302 }
303
304 inline bool ShenandoahHeap::is_idle() const {
305 return _gc_state.is_unset(MARKING | EVACUATION | UPDATEREFS);
306 }
307
308 inline bool ShenandoahHeap::is_concurrent_mark_in_progress() const {
309 return _gc_state.is_set(MARKING);
310 }
311
312 inline bool ShenandoahHeap::is_evacuation_in_progress() const {
313 return _gc_state.is_set(EVACUATION);
314 }
315
316 inline bool ShenandoahHeap::is_gc_in_progress_mask(uint mask) const {
317 return _gc_state.is_set(mask);
318 }
319
320 inline bool ShenandoahHeap::is_degenerated_gc_in_progress() const {
321 return _degenerated_gc_in_progress.is_set();
322 }
323
324 inline bool ShenandoahHeap::is_full_gc_in_progress() const {
325 return _full_gc_in_progress.is_set();
326 }
327
328 inline bool ShenandoahHeap::is_full_gc_move_in_progress() const {
329 return _full_gc_move_in_progress.is_set();
330 }
331
332 inline bool ShenandoahHeap::is_update_refs_in_progress() const {
333 return _gc_state.is_set(UPDATEREFS);
334 }
335
336 inline bool ShenandoahHeap::is_stw_gc_in_progress() const {
337 return is_full_gc_in_progress() || is_degenerated_gc_in_progress();
338 }
339
340 inline bool ShenandoahHeap::is_concurrent_strong_root_in_progress() const {
341 return _concurrent_strong_root_in_progress.is_set();
342 }
343
344 inline bool ShenandoahHeap::is_concurrent_weak_root_in_progress() const {
345 return _gc_state.is_set(WEAK_ROOTS);
346 }
347
348 template<class T>
349 inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl) {
350 marked_object_iterate(region, cl, region->top());
351 }
352
353 template<class T>
354 inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit) {
355 assert(! region->is_humongous_continuation(), "no humongous continuation regions here");
356
357 ShenandoahMarkingContext* const ctx = complete_marking_context();
358 assert(ctx->is_complete(), "sanity");
359
360 HeapWord* tams = ctx->top_at_mark_start(region);
361
362 size_t skip_bitmap_delta = 1;
363 HeapWord* start = region->bottom();
364 HeapWord* end = MIN2(tams, region->end());
365
366 // Step 1. Scan below the TAMS based on bitmap data.
367 HeapWord* limit_bitmap = MIN2(limit, tams);
368
369 // Try to scan the initial candidate. If the candidate is above the TAMS, it would
370 // fail the subsequent "< limit_bitmap" checks, and fall through to Step 2.
371 HeapWord* cb = ctx->get_next_marked_addr(start, end);
372
373 intx dist = ShenandoahMarkScanPrefetch;
374 if (dist > 0) {
375 // Batched scan that prefetches the oop data, anticipating the access to
376 // either header, oop field, or forwarding pointer. Not that we cannot
377 // touch anything in oop, while it still being prefetched to get enough
378 // time for prefetch to work. This is why we try to scan the bitmap linearly,
379 // disregarding the object size. However, since we know forwarding pointer
380 // preceeds the object, we can skip over it. Once we cannot trust the bitmap,
381 // there is no point for prefetching the oop contents, as oop->size() will
382 // touch it prematurely.
383
384 // No variable-length arrays in standard C++, have enough slots to fit
385 // the prefetch distance.
386 static const int SLOT_COUNT = 256;
387 guarantee(dist <= SLOT_COUNT, "adjust slot count");
388 HeapWord* slots[SLOT_COUNT];
389
390 int avail;
391 do {
392 avail = 0;
393 for (int c = 0; (c < dist) && (cb < limit_bitmap); c++) {
394 Prefetch::read(cb, oopDesc::mark_offset_in_bytes());
395 slots[avail++] = cb;
396 cb += skip_bitmap_delta;
397 if (cb < limit_bitmap) {
398 cb = ctx->get_next_marked_addr(cb, limit_bitmap);
399 }
400 }
401
402 for (int c = 0; c < avail; c++) {
403 assert (slots[c] < tams, "only objects below TAMS here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(slots[c]), p2i(tams));
404 assert (slots[c] < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(slots[c]), p2i(limit));
405 oop obj = cast_to_oop(slots[c]);
406 assert(oopDesc::is_oop(obj), "sanity");
407 assert(ctx->is_marked(obj), "object expected to be marked");
408 cl->do_object(obj);
409 }
410 } while (avail > 0);
411 } else {
412 while (cb < limit_bitmap) {
413 assert (cb < tams, "only objects below TAMS here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cb), p2i(tams));
414 assert (cb < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cb), p2i(limit));
415 oop obj = cast_to_oop(cb);
416 assert(oopDesc::is_oop(obj), "sanity");
417 assert(ctx->is_marked(obj), "object expected to be marked");
418 cl->do_object(obj);
419 cb += skip_bitmap_delta;
420 if (cb < limit_bitmap) {
421 cb = ctx->get_next_marked_addr(cb, limit_bitmap);
422 }
423 }
424 }
425
426 // Step 2. Accurate size-based traversal, happens past the TAMS.
427 // This restarts the scan at TAMS, which makes sure we traverse all objects,
428 // regardless of what happened at Step 1.
429 HeapWord* cs = tams;
430 while (cs < limit) {
431 assert (cs >= tams, "only objects past TAMS here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cs), p2i(tams));
432 assert (cs < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cs), p2i(limit));
433 oop obj = cast_to_oop(cs);
434 assert(oopDesc::is_oop(obj), "sanity");
435 assert(ctx->is_marked(obj), "object expected to be marked");
436 size_t size = ShenandoahObjectUtils::size(obj);
437 cl->do_object(obj);
438 cs += size;
439 }
440 }
441
442 template <class T>
443 class ShenandoahObjectToOopClosure : public ObjectClosure {
444 T* _cl;
445 public:
446 ShenandoahObjectToOopClosure(T* cl) : _cl(cl) {}
447
448 void do_object(oop obj) {
449 obj->oop_iterate(_cl);
450 }
451 };
452
453 template <class T>
454 class ShenandoahObjectToOopBoundedClosure : public ObjectClosure {
455 T* _cl;
456 MemRegion _bounds;
457 public:
458 ShenandoahObjectToOopBoundedClosure(T* cl, HeapWord* bottom, HeapWord* top) :
459 _cl(cl), _bounds(bottom, top) {}
460
461 void do_object(oop obj) {
462 obj->oop_iterate(_cl, _bounds);
463 }
464 };
465
466 template<class T>
467 inline void ShenandoahHeap::marked_object_oop_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* top) {
468 if (region->is_humongous()) {
469 HeapWord* bottom = region->bottom();
470 if (top > bottom) {
471 region = region->humongous_start_region();
472 ShenandoahObjectToOopBoundedClosure<T> objs(cl, bottom, top);
473 marked_object_iterate(region, &objs);
474 }
475 } else {
476 ShenandoahObjectToOopClosure<T> objs(cl);
477 marked_object_iterate(region, &objs, top);
478 }
479 }
480
481 inline ShenandoahHeapRegion* const ShenandoahHeap::get_region(size_t region_idx) const {
482 if (region_idx < _num_regions) {
483 return _regions[region_idx];
484 } else {
485 return NULL;
486 }
487 }
488
489 inline void ShenandoahHeap::mark_complete_marking_context() {
490 _marking_context->mark_complete();
491 }
492
493 inline void ShenandoahHeap::mark_incomplete_marking_context() {
494 _marking_context->mark_incomplete();
495 }
496
497 inline ShenandoahMarkingContext* ShenandoahHeap::complete_marking_context() const {
498 assert (_marking_context->is_complete()," sanity");
499 return _marking_context;
500 }
501
502 inline ShenandoahMarkingContext* ShenandoahHeap::marking_context() const {
503 return _marking_context;
504 }
505
506 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP