1 /*
2 * Copyright (c) 2015, 2022, 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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24
25 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHMARK_INLINE_HPP
26 #define SHARE_GC_SHENANDOAH_SHENANDOAHMARK_INLINE_HPP
27
28 #include "gc/shenandoah/shenandoahMark.hpp"
29
30 #include "gc/shared/continuationGCSupport.inline.hpp"
31 #include "gc/shenandoah/shenandoahAsserts.hpp"
32 #include "gc/shenandoah/shenandoahBarrierSet.inline.hpp"
33 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
34 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
35 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
36 #include "gc/shenandoah/shenandoahStringDedup.inline.hpp"
37 #include "gc/shenandoah/shenandoahTaskqueue.inline.hpp"
38 #include "gc/shenandoah/shenandoahUtils.hpp"
39 #include "memory/iterator.inline.hpp"
40 #include "oops/compressedOops.inline.hpp"
41 #include "oops/oop.inline.hpp"
42 #include "runtime/prefetch.inline.hpp"
43 #include "utilities/devirtualizer.inline.hpp"
44 #include "utilities/powerOfTwo.hpp"
45
46 template <StringDedupMode STRING_DEDUP>
47 void ShenandoahMark::dedup_string(oop obj, StringDedup::Requests* const req) {
48 if (STRING_DEDUP == ENQUEUE_DEDUP) {
49 if (ShenandoahStringDedup::is_candidate(obj)) {
50 req->add(obj);
51 }
52 } else if (STRING_DEDUP == ALWAYS_DEDUP) {
53 if (ShenandoahStringDedup::is_string_candidate(obj) &&
54 !ShenandoahStringDedup::dedup_requested(obj)) {
55 req->add(obj);
56 }
57 }
58 }
59
60 template <class T, ShenandoahGenerationType GENERATION, StringDedupMode STRING_DEDUP>
61 void ShenandoahMark::do_task(ShenandoahObjToScanQueue* q, T* cl, ShenandoahLiveData* live_data, StringDedup::Requests* const req, ShenandoahMarkTask* task) {
62 oop obj = task->obj();
63
64 shenandoah_assert_not_forwarded(nullptr, obj);
65 shenandoah_assert_marked(nullptr, obj);
66 shenandoah_assert_not_in_cset_except(nullptr, obj, ShenandoahHeap::heap()->cancelled_gc());
67
68 // Are we in weak subgraph scan?
69 bool weak = task->is_weak();
70 cl->set_weak(weak);
71
72 if (task->is_not_chunked()) {
73 if (obj->is_instance()) {
74 // Case 1: Normal oop, process as usual.
75 if (ContinuationGCSupport::relativize_stack_chunk(obj)) {
76 // Loom doesn't support mixing of weak marking and strong marking of
77 // stack chunks.
78 cl->set_weak(false);
79 }
80
81 obj->oop_iterate(cl);
82 dedup_string<STRING_DEDUP>(obj, req);
83 } else if (obj->is_objArray()) {
84 // Case 2: Object array instance and no chunk is set. Must be the first
85 // time we visit it, start the chunked processing.
86 do_chunked_array_start<T>(q, cl, obj, weak);
87 } else {
88 // Case 3: Primitive array. Do nothing, no oops there. We use the same
89 // performance tweak TypeArrayKlass::oop_oop_iterate_impl is using:
90 // We skip iterating over the klass pointer since we know that
91 // Universe::TypeArrayKlass never moves.
92 assert (obj->is_typeArray(), "should be type array");
93 }
94 // Count liveness the last: push the outstanding work to the queues first
95 // Avoid double-counting objects that are visited twice due to upgrade
96 // from final- to strong mark.
97 if (task->count_liveness()) {
98 count_liveness<GENERATION>(live_data, obj);
99 }
100 } else {
101 // Case 4: Array chunk, has sensible chunk id. Process it.
102 do_chunked_array<T>(q, cl, obj, task->chunk(), task->pow(), weak);
103 }
104 }
105
106 template <ShenandoahGenerationType GENERATION>
107 inline void ShenandoahMark::count_liveness(ShenandoahLiveData* live_data, oop obj) {
108 ShenandoahHeap* const heap = ShenandoahHeap::heap();
109 size_t region_idx = heap->heap_region_index_containing(obj);
110 ShenandoahHeapRegion* region = heap->get_region(region_idx);
111 size_t size = obj->size();
112
113 if (!region->is_humongous_start()) {
114 assert(!region->is_humongous(), "Cannot have continuations here");
115 ShenandoahLiveData cur = live_data[region_idx];
116 size_t new_val = size + cur;
117 if (new_val >= SHENANDOAH_LIVEDATA_MAX) {
118 // overflow, flush to region data
119 region->increase_live_data_gc_words(new_val);
120 live_data[region_idx] = 0;
121 } else {
122 // still good, remember in locals
123 live_data[region_idx] = (ShenandoahLiveData) new_val;
124 }
125 } else {
126 shenandoah_assert_in_correct_region(nullptr, obj);
127 size_t num_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
128
129 for (size_t i = region_idx; i < region_idx + num_regions; i++) {
130 ShenandoahHeapRegion* chain_reg = heap->get_region(i);
131 assert(chain_reg->is_humongous(), "Expecting a humongous region");
132 chain_reg->increase_live_data_gc_words(chain_reg->used() >> LogHeapWordSize);
133 }
134 }
135 }
136
137 template <class T>
138 inline void ShenandoahMark::do_chunked_array_start(ShenandoahObjToScanQueue* q, T* cl, oop obj, bool weak) {
139 assert(obj->is_objArray(), "expect object array");
140 objArrayOop array = objArrayOop(obj);
141 int len = array->length();
142
143 // Mark objArray klass metadata
144 if (Devirtualizer::do_metadata(cl)) {
145 Devirtualizer::do_klass(cl, array->klass());
146 }
147
148 if (len <= (int) ObjArrayMarkingStride*2) {
149 // A few slices only, process directly
150 array->oop_iterate_range(cl, 0, len);
151 } else {
152 int bits = log2i_graceful(len);
153 // Compensate for non-power-of-two arrays, cover the array in excess:
154 if (len != (1 << bits)) bits++;
155
156 // Only allow full chunks on the queue. This frees do_chunked_array() from checking from/to
157 // boundaries against array->length(), touching the array header on every chunk.
158 //
159 // To do this, we cut the prefix in full-sized chunks, and submit them on the queue.
160 // If the array is not divided in chunk sizes, then there would be an irregular tail,
161 // which we will process separately.
162
163 int last_idx = 0;
164
165 int chunk = 1;
166 int pow = bits;
167
168 // Handle overflow
169 if (pow >= 31) {
170 assert (pow == 31, "sanity");
171 pow--;
172 chunk = 2;
173 last_idx = (1 << pow);
174 bool pushed = q->push(ShenandoahMarkTask(array, true, weak, 1, pow));
175 assert(pushed, "overflow queue should always succeed pushing");
176 }
177
178 // Split out tasks, as suggested in ShenandoahMarkTask docs. Record the last
179 // successful right boundary to figure out the irregular tail.
180 while ((1 << pow) > (int)ObjArrayMarkingStride &&
181 (chunk*2 < ShenandoahMarkTask::chunk_size())) {
182 pow--;
183 int left_chunk = chunk*2 - 1;
184 int right_chunk = chunk*2;
185 int left_chunk_end = left_chunk * (1 << pow);
186 if (left_chunk_end < len) {
187 bool pushed = q->push(ShenandoahMarkTask(array, true, weak, left_chunk, pow));
188 assert(pushed, "overflow queue should always succeed pushing");
189 chunk = right_chunk;
190 last_idx = left_chunk_end;
191 } else {
192 chunk = left_chunk;
193 }
194 }
195
196 // Process the irregular tail, if present
197 int from = last_idx;
198 if (from < len) {
199 array->oop_iterate_range(cl, from, len);
200 }
201 }
202 }
203
204 template <class T>
205 inline void ShenandoahMark::do_chunked_array(ShenandoahObjToScanQueue* q, T* cl, oop obj, int chunk, int pow, bool weak) {
206 assert(obj->is_objArray(), "expect object array");
207 objArrayOop array = objArrayOop(obj);
208
209 assert (ObjArrayMarkingStride > 0, "sanity");
210
211 // Split out tasks, as suggested in ShenandoahMarkTask docs. Avoid pushing tasks that
212 // are known to start beyond the array.
213 while ((1 << pow) > (int)ObjArrayMarkingStride && (chunk*2 < ShenandoahMarkTask::chunk_size())) {
214 pow--;
215 chunk *= 2;
216 bool pushed = q->push(ShenandoahMarkTask(array, true, weak, chunk - 1, pow));
217 assert(pushed, "overflow queue should always succeed pushing");
218 }
219
220 int chunk_size = 1 << pow;
221
222 int from = (chunk - 1) * chunk_size;
223 int to = chunk * chunk_size;
224
225 #ifdef ASSERT
226 int len = array->length();
227 assert (0 <= from && from < len, "from is sane: %d/%d", from, len);
228 assert (0 < to && to <= len, "to is sane: %d/%d", to, len);
229 #endif
230
231 array->oop_iterate_range(cl, from, to);
232 }
233
234 template <ShenandoahGenerationType GENERATION>
235 class ShenandoahSATBBufferClosure : public SATBBufferClosure {
236 private:
237 ShenandoahObjToScanQueue* _queue;
238 ShenandoahHeap* _heap;
239 ShenandoahMarkingContext* const _mark_context;
240 public:
241 ShenandoahSATBBufferClosure(ShenandoahObjToScanQueue* q) :
242 _queue(q),
243 _heap(ShenandoahHeap::heap()),
244 _mark_context(_heap->marking_context())
245 {
246 }
247
248 void do_buffer(void **buffer, size_t size) {
249 assert(size == 0 || !_heap->has_forwarded_objects(), "Forwarded objects are not expected here");
250 for (size_t i = 0; i < size; ++i) {
251 oop *p = (oop *) &buffer[i];
252 ShenandoahMark::mark_through_ref<oop, GENERATION>(p, _queue, _mark_context, false);
253 }
254 }
255 };
256
257 template<class T, ShenandoahGenerationType GENERATION>
258 inline void ShenandoahMark::mark_through_ref(T* p, ShenandoahObjToScanQueue* q, ShenandoahMarkingContext* const mark_context, bool weak) {
259 T o = RawAccess<>::oop_load(p);
260 if (!CompressedOops::is_null(o)) {
261 oop obj = CompressedOops::decode_not_null(o);
262
263 shenandoah_assert_not_forwarded(p, obj);
264 shenandoah_assert_not_in_cset_except(p, obj, ShenandoahHeap::heap()->cancelled_gc());
265
266 bool skip_live = false;
267 bool marked;
268 if (weak) {
269 marked = mark_context->mark_weak(obj);
270 } else {
271 marked = mark_context->mark_strong(obj, /* was_upgraded = */ skip_live);
272 }
273 if (marked) {
274 bool pushed = q->push(ShenandoahMarkTask(obj, skip_live, weak));
275 assert(pushed, "overflow queue should always succeed pushing");
276 }
277
278 shenandoah_assert_marked(p, obj);
279 }
280 }
281
282 ShenandoahObjToScanQueueSet* ShenandoahMark::task_queues() const {
283 return _task_queues;
284 }
285
286 ShenandoahObjToScanQueue* ShenandoahMark::get_queue(uint index) const {
287 return _task_queues->queue(index);
288 }
289 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHMARK_INLINE_HPP