1 /*
2 * Copyright (c) 2015, 2019, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP
25 #define SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP
26
27 #include "classfile/javaClasses.inline.hpp"
28 #include "gc/shared/markBitMap.inline.hpp"
29 #include "gc/shared/threadLocalAllocBuffer.inline.hpp"
30 #include "gc/shared/suspendibleThreadSet.hpp"
31 #include "gc/shenandoah/shenandoahAsserts.hpp"
32 #include "gc/shenandoah/shenandoahBarrierSet.inline.hpp"
33 #include "gc/shenandoah/shenandoahCollectionSet.inline.hpp"
34 #include "gc/shenandoah/shenandoahForwarding.inline.hpp"
35 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
36 #include "gc/shenandoah/shenandoahHeap.hpp"
37 #include "gc/shenandoah/shenandoahHeapRegionSet.inline.hpp"
38 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
39 #include "gc/shenandoah/shenandoahControlThread.hpp"
40 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
41 #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
42 #include "oops/oop.inline.hpp"
43 #include "runtime/atomic.hpp"
44 #include "runtime/prefetch.inline.hpp"
45 #include "runtime/thread.hpp"
46 #include "utilities/copy.hpp"
47 #include "utilities/globalDefinitions.hpp"
48
49
50 inline ShenandoahHeapRegion* ShenandoahRegionIterator::next() {
51 size_t new_index = Atomic::add((size_t) 1, &_index);
52 // get_region() provides the bounds-check and returns NULL on OOB.
53 return _heap->get_region(new_index - 1);
54 }
55
56 inline bool ShenandoahHeap::has_forwarded_objects() const {
57 return _gc_state.is_set(HAS_FORWARDED);
58 }
59
60 inline WorkGang* ShenandoahHeap::workers() const {
61 return _workers;
62 }
63
64 inline WorkGang* ShenandoahHeap::get_safepoint_workers() {
65 return _safepoint_workers;
66 }
67
68 inline size_t ShenandoahHeap::heap_region_index_containing(const void* addr) const {
69 uintptr_t region_start = ((uintptr_t) addr);
70 uintptr_t index = (region_start - (uintptr_t) base()) >> ShenandoahHeapRegion::region_size_bytes_shift();
71 assert(index < num_regions(), "Region index is in bounds: " PTR_FORMAT, p2i(addr));
72 return index;
73 }
74
75 inline ShenandoahHeapRegion* const ShenandoahHeap::heap_region_containing(const void* addr) const {
76 size_t index = heap_region_index_containing(addr);
77 ShenandoahHeapRegion* const result = get_region(index);
78 assert(addr >= result->bottom() && addr < result->end(), "Heap region contains the address: " PTR_FORMAT, p2i(addr));
79 return result;
80 }
81
82 template <class T>
83 inline oop ShenandoahHeap::update_with_forwarded_not_null(T* p, oop obj) {
84 if (in_collection_set(obj)) {
85 shenandoah_assert_forwarded_except(p, obj, is_full_gc_in_progress() || cancelled_gc() || is_degenerated_gc_in_progress());
86 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
87 RawAccess<IS_NOT_NULL>::oop_store(p, obj);
88 }
89 #ifdef ASSERT
90 else {
91 shenandoah_assert_not_forwarded(p, obj);
92 }
93 #endif
94 return obj;
95 }
96
97 template <class T>
98 inline oop ShenandoahHeap::maybe_update_with_forwarded(T* p) {
99 T o = RawAccess<>::oop_load(p);
100 if (!CompressedOops::is_null(o)) {
101 oop obj = CompressedOops::decode_not_null(o);
102 return maybe_update_with_forwarded_not_null(p, obj);
103 } else {
104 return NULL;
105 }
106 }
107
108 template <class T>
109 inline oop ShenandoahHeap::evac_update_with_forwarded(T* p) {
110 T o = RawAccess<>::oop_load(p);
111 if (!CompressedOops::is_null(o)) {
112 oop heap_oop = CompressedOops::decode_not_null(o);
113 if (in_collection_set(heap_oop)) {
114 oop forwarded_oop = ShenandoahBarrierSet::resolve_forwarded_not_null(heap_oop);
115 if (oopDesc::equals_raw(forwarded_oop, heap_oop)) {
116 forwarded_oop = evacuate_object(heap_oop, Thread::current());
117 }
118 oop prev = atomic_compare_exchange_oop(forwarded_oop, p, heap_oop);
119 if (oopDesc::equals_raw(prev, heap_oop)) {
120 return forwarded_oop;
121 } else {
122 return NULL;
123 }
124 }
125 return heap_oop;
126 } else {
127 return NULL;
128 }
129 }
130
131 inline oop ShenandoahHeap::atomic_compare_exchange_oop(oop n, oop* addr, oop c) {
132 return (oop) Atomic::cmpxchg(n, addr, c);
133 }
134
135 inline oop ShenandoahHeap::atomic_compare_exchange_oop(oop n, narrowOop* addr, oop c) {
136 narrowOop cmp = CompressedOops::encode(c);
137 narrowOop val = CompressedOops::encode(n);
138 return CompressedOops::decode((narrowOop) Atomic::cmpxchg(val, addr, cmp));
139 }
140
141 template <class T>
142 inline oop ShenandoahHeap::maybe_update_with_forwarded_not_null(T* p, oop heap_oop) {
143 shenandoah_assert_not_in_cset_loc_except(p, !is_in(p) || is_full_gc_in_progress() || is_degenerated_gc_in_progress());
144 shenandoah_assert_correct(p, heap_oop);
145
146 if (in_collection_set(heap_oop)) {
147 oop forwarded_oop = ShenandoahBarrierSet::resolve_forwarded_not_null(heap_oop);
148 if (oopDesc::equals_raw(forwarded_oop, heap_oop)) {
149 // E.g. during evacuation.
150 return forwarded_oop;
151 }
152
153 shenandoah_assert_forwarded_except(p, heap_oop, is_full_gc_in_progress() || is_degenerated_gc_in_progress());
154 shenandoah_assert_not_in_cset_except(p, forwarded_oop, cancelled_gc());
155
156 // If this fails, another thread wrote to p before us, it will be logged in SATB and the
157 // reference be updated later.
158 oop result = atomic_compare_exchange_oop(forwarded_oop, p, heap_oop);
159
160 if (oopDesc::equals_raw(result, heap_oop)) { // CAS successful.
161 return forwarded_oop;
162 } else {
163 // Note: we used to assert the following here. This doesn't work because sometimes, during
164 // marking/updating-refs, it can happen that a Java thread beats us with an arraycopy,
165 // which first copies the array, which potentially contains from-space refs, and only afterwards
166 // updates all from-space refs to to-space refs, which leaves a short window where the new array
167 // elements can be from-space.
168 // assert(CompressedOops::is_null(result) ||
169 // oopDesc::equals_raw(result, ShenandoahBarrierSet::resolve_oop_static_not_null(result)),
170 // "expect not forwarded");
171 return NULL;
172 }
173 } else {
174 shenandoah_assert_not_forwarded(p, heap_oop);
175 return heap_oop;
176 }
177 }
178
179 inline bool ShenandoahHeap::cancelled_gc() const {
180 return _cancelled_gc.get() == CANCELLED;
181 }
182
183 inline bool ShenandoahHeap::check_cancelled_gc_and_yield(bool sts_active) {
184 if (! (sts_active && ShenandoahSuspendibleWorkers)) {
185 return cancelled_gc();
186 }
187
188 jbyte prev = _cancelled_gc.cmpxchg(NOT_CANCELLED, CANCELLABLE);
189 if (prev == CANCELLABLE || prev == NOT_CANCELLED) {
190 if (SuspendibleThreadSet::should_yield()) {
191 SuspendibleThreadSet::yield();
192 }
193
194 // Back to CANCELLABLE. The thread that poked NOT_CANCELLED first gets
195 // to restore to CANCELLABLE.
196 if (prev == CANCELLABLE) {
197 _cancelled_gc.set(CANCELLABLE);
198 }
199 return false;
200 } else {
201 return true;
202 }
203 }
204
205 inline void ShenandoahHeap::clear_cancelled_gc() {
206 _cancelled_gc.set(CANCELLABLE);
207 _oom_evac_handler.clear();
208 }
209
210 inline HeapWord* ShenandoahHeap::allocate_from_gclab(Thread* thread, size_t size) {
211 assert(UseTLAB, "TLABs should be enabled");
212
213 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
214 if (gclab == NULL) {
215 assert(!thread->is_Java_thread() && !thread->is_Worker_thread(),
216 "Performance: thread should have GCLAB: %s", thread->name());
217 // No GCLABs in this thread, fallback to shared allocation
218 return NULL;
219 }
220 HeapWord* obj = gclab->allocate(size);
221 if (obj != NULL) {
222 return obj;
223 }
224 // Otherwise...
225 return allocate_from_gclab_slow(thread, size);
226 }
227
228 inline oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) {
229 if (ShenandoahThreadLocalData::is_oom_during_evac(Thread::current())) {
230 // This thread went through the OOM during evac protocol and it is safe to return
231 // the forward pointer. It must not attempt to evacuate any more.
232 return ShenandoahBarrierSet::resolve_forwarded(p);
233 }
234
235 assert(ShenandoahThreadLocalData::is_evac_allowed(thread), "must be enclosed in oom-evac scope");
236
237 size_t size = p->size();
238
239 assert(!heap_region_containing(p)->is_humongous(), "never evacuate humongous objects");
240
241 bool alloc_from_gclab = true;
242 HeapWord* copy = NULL;
243
244 #ifdef ASSERT
245 if (ShenandoahOOMDuringEvacALot &&
246 (os::random() & 1) == 0) { // Simulate OOM every ~2nd slow-path call
247 copy = NULL;
248 } else {
249 #endif
250 if (UseTLAB) {
251 copy = allocate_from_gclab(thread, size);
252 }
253 if (copy == NULL) {
254 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared_gc(size);
255 copy = allocate_memory(req);
256 alloc_from_gclab = false;
257 }
258 #ifdef ASSERT
259 }
260 #endif
261
262 if (copy == NULL) {
263 control_thread()->handle_alloc_failure_evac(size);
264
265 _oom_evac_handler.handle_out_of_memory_during_evacuation();
266
267 return ShenandoahBarrierSet::resolve_forwarded(p);
268 }
269
270 // Copy the object:
271 Copy::aligned_disjoint_words((HeapWord*) p, copy, size);
272
273 // Try to install the new forwarding pointer.
274 oop copy_val = oop(copy);
275 oop result = ShenandoahForwarding::try_update_forwardee(p, copy_val);
276 if (oopDesc::equals_raw(result, p)) {
277 // Successfully evacuated. Our copy is now the public one!
278 shenandoah_assert_correct(NULL, copy_val);
279 return copy_val;
280 } else {
281 // Failed to evacuate. We need to deal with the object that is left behind. Since this
282 // new allocation is certainly after TAMS, it will be considered live in the next cycle.
283 // But if it happens to contain references to evacuated regions, those references would
284 // not get updated for this stale copy during this cycle, and we will crash while scanning
285 // it the next cycle.
286 //
287 // For GCLAB allocations, it is enough to rollback the allocation ptr. Either the next
288 // object will overwrite this stale copy, or the filler object on LAB retirement will
289 // do this. For non-GCLAB allocations, we have no way to retract the allocation, and
290 // have to explicitly overwrite the copy with the filler object. With that overwrite,
291 // we have to keep the fwdptr initialized and pointing to our (stale) copy.
292 if (alloc_from_gclab) {
293 ShenandoahThreadLocalData::gclab(thread)->undo_allocation(copy, size);
294 } else {
295 fill_with_object(copy, size);
296 shenandoah_assert_correct(NULL, copy_val);
297 }
298 shenandoah_assert_correct(NULL, result);
299 return result;
300 }
301 }
302
303 template<bool RESOLVE>
304 inline bool ShenandoahHeap::requires_marking(const void* entry) const {
305 oop obj = oop(entry);
306 if (RESOLVE) {
307 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
308 }
309 return !_marking_context->is_marked(obj);
310 }
311
312 template <class T>
313 inline bool ShenandoahHeap::in_collection_set(T p) const {
314 HeapWord* obj = (HeapWord*) p;
315 assert(collection_set() != NULL, "Sanity");
316 assert(is_in(obj), "should be in heap");
317
318 return collection_set()->is_in(obj);
319 }
320
321 inline bool ShenandoahHeap::is_stable() const {
322 return _gc_state.is_clear();
323 }
324
325 inline bool ShenandoahHeap::is_idle() const {
326 return _gc_state.is_unset(MARKING | EVACUATION | UPDATEREFS | TRAVERSAL);
327 }
328
329 inline bool ShenandoahHeap::is_concurrent_mark_in_progress() const {
330 return _gc_state.is_set(MARKING);
331 }
332
333 inline bool ShenandoahHeap::is_concurrent_traversal_in_progress() const {
334 return _gc_state.is_set(TRAVERSAL);
335 }
336
337 inline bool ShenandoahHeap::is_evacuation_in_progress() const {
338 return _gc_state.is_set(EVACUATION);
339 }
340
341 inline bool ShenandoahHeap::is_gc_in_progress_mask(uint mask) const {
342 return _gc_state.is_set(mask);
343 }
344
345 inline bool ShenandoahHeap::is_degenerated_gc_in_progress() const {
346 return _degenerated_gc_in_progress.is_set();
347 }
348
349 inline bool ShenandoahHeap::is_full_gc_in_progress() const {
350 return _full_gc_in_progress.is_set();
351 }
352
353 inline bool ShenandoahHeap::is_full_gc_move_in_progress() const {
354 return _full_gc_move_in_progress.is_set();
355 }
356
357 inline bool ShenandoahHeap::is_update_refs_in_progress() const {
358 return _gc_state.is_set(UPDATEREFS);
359 }
360
361 template<class T>
362 inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl) {
363 marked_object_iterate(region, cl, region->top());
364 }
365
366 template<class T>
367 inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit) {
368 assert(! region->is_humongous_continuation(), "no humongous continuation regions here");
369
370 ShenandoahMarkingContext* const ctx = complete_marking_context();
371 assert(ctx->is_complete(), "sanity");
372
373 MarkBitMap* mark_bit_map = ctx->mark_bit_map();
374 HeapWord* tams = ctx->top_at_mark_start(region);
375
376 size_t skip_bitmap_delta = 1;
377 HeapWord* start = region->bottom();
378 HeapWord* end = MIN2(tams, region->end());
379
380 // Step 1. Scan below the TAMS based on bitmap data.
381 HeapWord* limit_bitmap = MIN2(limit, tams);
382
383 // Try to scan the initial candidate. If the candidate is above the TAMS, it would
384 // fail the subsequent "< limit_bitmap" checks, and fall through to Step 2.
385 HeapWord* cb = mark_bit_map->get_next_marked_addr(start, end);
386
387 intx dist = ShenandoahMarkScanPrefetch;
388 if (dist > 0) {
389 // Batched scan that prefetches the oop data, anticipating the access to
390 // either header, oop field, or forwarding pointer. Not that we cannot
391 // touch anything in oop, while it still being prefetched to get enough
392 // time for prefetch to work. This is why we try to scan the bitmap linearly,
393 // disregarding the object size. However, since we know forwarding pointer
394 // preceeds the object, we can skip over it. Once we cannot trust the bitmap,
395 // there is no point for prefetching the oop contents, as oop->size() will
396 // touch it prematurely.
397
398 // No variable-length arrays in standard C++, have enough slots to fit
399 // the prefetch distance.
400 static const int SLOT_COUNT = 256;
401 guarantee(dist <= SLOT_COUNT, "adjust slot count");
402 HeapWord* slots[SLOT_COUNT];
403
404 int avail;
405 do {
406 avail = 0;
407 for (int c = 0; (c < dist) && (cb < limit_bitmap); c++) {
408 Prefetch::read(cb, oopDesc::mark_offset_in_bytes());
409 slots[avail++] = cb;
410 cb += skip_bitmap_delta;
411 if (cb < limit_bitmap) {
412 cb = mark_bit_map->get_next_marked_addr(cb, limit_bitmap);
413 }
414 }
415
416 for (int c = 0; c < avail; c++) {
417 assert (slots[c] < tams, "only objects below TAMS here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(slots[c]), p2i(tams));
418 assert (slots[c] < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(slots[c]), p2i(limit));
419 oop obj = oop(slots[c]);
420 assert(oopDesc::is_oop(obj), "sanity");
421 assert(ctx->is_marked(obj), "object expected to be marked");
422 cl->do_object(obj);
423 }
424 } while (avail > 0);
425 } else {
426 while (cb < limit_bitmap) {
427 assert (cb < tams, "only objects below TAMS here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cb), p2i(tams));
428 assert (cb < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cb), p2i(limit));
429 oop obj = oop(cb);
430 assert(oopDesc::is_oop(obj), "sanity");
431 assert(ctx->is_marked(obj), "object expected to be marked");
432 cl->do_object(obj);
433 cb += skip_bitmap_delta;
434 if (cb < limit_bitmap) {
435 cb = mark_bit_map->get_next_marked_addr(cb, limit_bitmap);
436 }
437 }
438 }
439
440 // Step 2. Accurate size-based traversal, happens past the TAMS.
441 // This restarts the scan at TAMS, which makes sure we traverse all objects,
442 // regardless of what happened at Step 1.
443 HeapWord* cs = tams;
444 while (cs < limit) {
445 assert (cs >= tams, "only objects past TAMS here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cs), p2i(tams));
446 assert (cs < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cs), p2i(limit));
447 oop obj = oop(cs);
448 assert(oopDesc::is_oop(obj), "sanity");
449 assert(ctx->is_marked(obj), "object expected to be marked");
450 int size = obj->size();
451 cl->do_object(obj);
452 cs += size;
453 }
454 }
455
456 template <class T>
457 class ShenandoahObjectToOopClosure : public ObjectClosure {
458 T* _cl;
459 public:
460 ShenandoahObjectToOopClosure(T* cl) : _cl(cl) {}
461
462 void do_object(oop obj) {
463 obj->oop_iterate(_cl);
464 }
465 };
466
467 template <class T>
468 class ShenandoahObjectToOopBoundedClosure : public ObjectClosure {
469 T* _cl;
470 MemRegion _bounds;
471 public:
472 ShenandoahObjectToOopBoundedClosure(T* cl, HeapWord* bottom, HeapWord* top) :
473 _cl(cl), _bounds(bottom, top) {}
474
475 void do_object(oop obj) {
476 obj->oop_iterate(_cl, _bounds);
477 }
478 };
479
480 template<class T>
481 inline void ShenandoahHeap::marked_object_oop_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* top) {
482 if (region->is_humongous()) {
483 HeapWord* bottom = region->bottom();
484 if (top > bottom) {
485 region = region->humongous_start_region();
486 ShenandoahObjectToOopBoundedClosure<T> objs(cl, bottom, top);
487 marked_object_iterate(region, &objs);
488 }
489 } else {
490 ShenandoahObjectToOopClosure<T> objs(cl);
491 marked_object_iterate(region, &objs, top);
492 }
493 }
494
495 inline ShenandoahHeapRegion* const ShenandoahHeap::get_region(size_t region_idx) const {
496 if (region_idx < _num_regions) {
497 return _regions[region_idx];
498 } else {
499 return NULL;
500 }
501 }
502
503 inline void ShenandoahHeap::mark_complete_marking_context() {
504 _marking_context->mark_complete();
505 }
506
507 inline void ShenandoahHeap::mark_incomplete_marking_context() {
508 _marking_context->mark_incomplete();
509 }
510
511 inline ShenandoahMarkingContext* ShenandoahHeap::complete_marking_context() const {
512 assert (_marking_context->is_complete()," sanity");
513 return _marking_context;
514 }
515
516 inline ShenandoahMarkingContext* ShenandoahHeap::marking_context() const {
517 return _marking_context;
518 }
519
520 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP