1 /*
2 * Copyright (c) 2013, 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 #include "precompiled.hpp"
25 #include "gc/shenandoah/shenandoahAsserts.hpp"
26 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
27 #include "gc/shenandoah/shenandoahBarrierSetClone.inline.hpp"
28 #include "gc/shenandoah/shenandoahBarrierSetAssembler.hpp"
29 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
30 #include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
31 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
32 #include "gc/shenandoah/shenandoahHeuristics.hpp"
33 #include "gc/shenandoah/shenandoahTraversalGC.hpp"
34 #include "memory/iterator.inline.hpp"
35 #include "runtime/interfaceSupport.inline.hpp"
36 #ifdef COMPILER1
37 #include "gc/shenandoah/c1/shenandoahBarrierSetC1.hpp"
38 #endif
39 #ifdef COMPILER2
40 #include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
41 #endif
42
43 class ShenandoahBarrierSetC1;
44 class ShenandoahBarrierSetC2;
45
46 ShenandoahBarrierSet::ShenandoahBarrierSet(ShenandoahHeap* heap) :
47 BarrierSet(make_barrier_set_assembler<ShenandoahBarrierSetAssembler>(),
48 make_barrier_set_c1<ShenandoahBarrierSetC1>(),
49 make_barrier_set_c2<ShenandoahBarrierSetC2>(),
50 NULL /* barrier_set_nmethod */,
51 BarrierSet::FakeRtti(BarrierSet::ShenandoahBarrierSet)),
52 _heap(heap),
53 _satb_mark_queue_buffer_allocator("SATB Buffer Allocator", ShenandoahSATBBufferSize),
54 _satb_mark_queue_set(&_satb_mark_queue_buffer_allocator)
55 {
56 }
57
58 ShenandoahBarrierSetAssembler* ShenandoahBarrierSet::assembler() {
59 BarrierSetAssembler* const bsa = BarrierSet::barrier_set()->barrier_set_assembler();
60 return reinterpret_cast<ShenandoahBarrierSetAssembler*>(bsa);
61 }
62
63 void ShenandoahBarrierSet::print_on(outputStream* st) const {
64 st->print("ShenandoahBarrierSet");
65 }
66
67 bool ShenandoahBarrierSet::is_a(BarrierSet::Name bsn) {
68 return bsn == BarrierSet::ShenandoahBarrierSet;
69 }
70
71 bool ShenandoahBarrierSet::is_aligned(HeapWord* hw) {
72 return true;
73 }
74
75 bool ShenandoahBarrierSet::need_load_reference_barrier(DecoratorSet decorators, BasicType type) {
76 if (!ShenandoahLoadRefBarrier) return false;
77 // Only needed for references
78 return is_reference_type(type);
79 }
80
81 bool ShenandoahBarrierSet::use_load_reference_barrier_native(DecoratorSet decorators, BasicType type) {
82 assert(need_load_reference_barrier(decorators, type), "Should be subset of LRB");
83 assert(is_reference_type(type), "Why we here?");
84 // Native load reference barrier is only needed for concurrent root processing
85 if (!ShenandoahConcurrentRoots::can_do_concurrent_roots()) {
86 return false;
87 }
88
89 return (decorators & IN_NATIVE) != 0;
90 }
91
92 bool ShenandoahBarrierSet::need_keep_alive_barrier(DecoratorSet decorators,BasicType type) {
93 if (!ShenandoahKeepAliveBarrier) return false;
94 // Only needed for references
95 if (!is_reference_type(type)) return false;
96
97 bool keep_alive = (decorators & AS_NO_KEEPALIVE) == 0;
98 bool unknown = (decorators & ON_UNKNOWN_OOP_REF) != 0;
99 bool is_traversal_mode = ShenandoahHeap::heap()->is_traversal_mode();
100 bool on_weak_ref = (decorators & (ON_WEAK_OOP_REF | ON_PHANTOM_OOP_REF)) != 0;
101 return (on_weak_ref || unknown) && (keep_alive || is_traversal_mode);
102 }
103
104 oop ShenandoahBarrierSet::load_reference_barrier_not_null(oop obj) {
105 if (ShenandoahLoadRefBarrier && _heap->has_forwarded_objects()) {
106 return load_reference_barrier_impl(obj);
107 } else {
108 return obj;
109 }
110 }
111
112 oop ShenandoahBarrierSet::load_reference_barrier(oop obj) {
113 if (obj != NULL) {
114 return load_reference_barrier_not_null(obj);
115 } else {
116 return obj;
117 }
118 }
119
120 oop ShenandoahBarrierSet::load_reference_barrier_mutator(oop obj, oop* load_addr) {
121 return load_reference_barrier_mutator_work(obj, load_addr);
122 }
123
124 oop ShenandoahBarrierSet::load_reference_barrier_mutator(oop obj, narrowOop* load_addr) {
125 return load_reference_barrier_mutator_work(obj, load_addr);
126 }
127
128 template <class T>
129 oop ShenandoahBarrierSet::load_reference_barrier_mutator_work(oop obj, T* load_addr) {
130 assert(ShenandoahLoadRefBarrier, "should be enabled");
131 shenandoah_assert_in_cset(load_addr, obj);
132
133 oop fwd = resolve_forwarded_not_null(obj);
134 if (obj == fwd) {
135 assert(_heap->is_gc_in_progress_mask(ShenandoahHeap::EVACUATION | ShenandoahHeap::TRAVERSAL),
136 "evac should be in progress");
137
138 ShenandoahEvacOOMScope oom_evac_scope;
139
140 Thread* thread = Thread::current();
141 oop res_oop = _heap->evacuate_object(obj, thread);
142
143 // Since we are already here and paid the price of getting through runtime call adapters
144 // and acquiring oom-scope, it makes sense to try and evacuate more adjacent objects,
145 // thus amortizing the overhead. For sparsely live heaps, scan costs easily dominate
146 // total assist costs, and can introduce a lot of evacuation latency. This is why we
147 // only scan for _nearest_ N objects, regardless if they are eligible for evac or not.
148 // The scan itself should also avoid touching the non-marked objects below TAMS, because
149 // their metadata (notably, klasses) may be incorrect already.
150
151 size_t max = ShenandoahEvacAssist;
152 if (max > 0) {
153 // Traversal is special: it uses incomplete marking context, because it coalesces evac with mark.
154 // Other code uses complete marking context, because evac happens after the mark.
155 ShenandoahMarkingContext* ctx = _heap->is_concurrent_traversal_in_progress() ?
156 _heap->marking_context() : _heap->complete_marking_context();
157
158 ShenandoahHeapRegion* r = _heap->heap_region_containing(obj);
159 assert(r->is_cset(), "sanity");
160
161 HeapWord* cur = (HeapWord*)obj + obj->size();
162
163 size_t count = 0;
164 while ((cur < r->top()) && ctx->is_marked(oop(cur)) && (count++ < max)) {
165 oop cur_oop = oop(cur);
166 if (cur_oop == resolve_forwarded_not_null(cur_oop)) {
167 _heap->evacuate_object(cur_oop, thread);
168 }
169 cur = cur + cur_oop->size();
170 }
171 }
172
173 fwd = res_oop;
174 }
175
176 if (load_addr != NULL && fwd != obj) {
177 // Since we are here and we know the load address, update the reference.
178 ShenandoahHeap::cas_oop(fwd, load_addr, obj);
179 }
180
181 return fwd;
182 }
183
184 oop ShenandoahBarrierSet::load_reference_barrier_impl(oop obj) {
185 assert(ShenandoahLoadRefBarrier, "should be enabled");
186 if (!CompressedOops::is_null(obj)) {
187 bool evac_in_progress = _heap->is_gc_in_progress_mask(ShenandoahHeap::EVACUATION | ShenandoahHeap::TRAVERSAL);
188 oop fwd = resolve_forwarded_not_null(obj);
189 if (evac_in_progress &&
190 _heap->in_collection_set(obj) &&
191 obj == fwd) {
192 Thread *t = Thread::current();
193 if (t->is_GC_task_thread()) {
194 return _heap->evacuate_object(obj, t);
195 } else {
196 ShenandoahEvacOOMScope oom_evac_scope;
197 return _heap->evacuate_object(obj, t);
198 }
199 } else {
200 return fwd;
201 }
202 } else {
203 return obj;
204 }
205 }
206
207 void ShenandoahBarrierSet::on_thread_create(Thread* thread) {
208 // Create thread local data
209 ShenandoahThreadLocalData::create(thread);
210 }
211
212 void ShenandoahBarrierSet::on_thread_destroy(Thread* thread) {
213 // Destroy thread local data
214 ShenandoahThreadLocalData::destroy(thread);
215 }
216
217 void ShenandoahBarrierSet::on_thread_attach(Thread *thread) {
218 assert(!thread->is_Java_thread() || !SafepointSynchronize::is_at_safepoint(),
219 "We should not be at a safepoint");
220 SATBMarkQueue& queue = ShenandoahThreadLocalData::satb_mark_queue(thread);
221 assert(!queue.is_active(), "SATB queue should not be active");
222 assert( queue.is_empty(), "SATB queue should be empty");
223 queue.set_active(_satb_mark_queue_set.is_active());
224 if (thread->is_Java_thread()) {
225 ShenandoahThreadLocalData::set_gc_state(thread, _heap->gc_state());
226 ShenandoahThreadLocalData::initialize_gclab(thread);
227 }
228 }
229
230 void ShenandoahBarrierSet::on_thread_detach(Thread *thread) {
231 SATBMarkQueue& queue = ShenandoahThreadLocalData::satb_mark_queue(thread);
232 queue.flush();
233 if (thread->is_Java_thread()) {
234 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
235 if (gclab != NULL) {
236 gclab->retire();
237 }
238 }
239 }
240
241 oop ShenandoahBarrierSet::load_reference_barrier_native(oop obj, oop* load_addr) {
242 return load_reference_barrier_native_impl(obj, load_addr);
243 }
244
245 oop ShenandoahBarrierSet::load_reference_barrier_native(oop obj, narrowOop* load_addr) {
246 // Assumption: narrow oop version should not be used anywhere.
247 ShouldNotReachHere();
248 return NULL;
249 }
250
251 template <class T>
252 oop ShenandoahBarrierSet::load_reference_barrier_native_impl(oop obj, T* load_addr) {
253 if (CompressedOops::is_null(obj)) {
254 return NULL;
255 }
256
257 ShenandoahMarkingContext* const marking_context = _heap->marking_context();
258 if (_heap->is_evacuation_in_progress() && !marking_context->is_marked(obj)) {
259 Thread* thr = Thread::current();
260 if (thr->is_Java_thread()) {
261 return NULL;
262 } else {
263 return obj;
264 }
265 }
266
267 oop fwd = load_reference_barrier_not_null(obj);
268 if (load_addr != NULL && fwd != obj) {
269 // Since we are here and we know the load address, update the reference.
270 ShenandoahHeap::cas_oop(fwd, load_addr, obj);
271 }
272
273 return fwd;
274 }
275
276 void ShenandoahBarrierSet::clone_barrier_runtime(oop src) {
277 if (_heap->has_forwarded_objects()) {
278 clone_barrier(src);
279 }
280 }
281