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