1 /*
2 * Copyright (c) 2015, 2018, 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_VM_GC_SHENANDOAH_SHENANDOAHCONCURRENTMARK_INLINE_HPP
25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHCONCURRENTMARK_INLINE_HPP
26
27 #include "gc_implementation/shenandoah/shenandoahAsserts.hpp"
28 #include "gc_implementation/shenandoah/shenandoahBarrierSet.inline.hpp"
29 #include "gc_implementation/shenandoah/shenandoahConcurrentMark.hpp"
30 #include "gc_implementation/shenandoah/shenandoahMarkingContext.inline.hpp"
31 #include "gc_implementation/shenandoah/shenandoahHeap.inline.hpp"
32 #include "gc_implementation/shenandoah/shenandoahOopClosures.inline.hpp"
33 #include "gc_implementation/shenandoah/shenandoahStringDedup.hpp"
34 #include "gc_implementation/shenandoah/shenandoahTaskqueue.inline.hpp"
35 #include "memory/iterator.inline.hpp"
36 #include "oops/oop.inline.hpp"
37 #include "runtime/prefetch.inline.hpp"
38
39 template <class T>
40 void ShenandoahConcurrentMark::do_task(ShenandoahObjToScanQueue* q, T* cl, ShenandoahLiveData* live_data, ShenandoahMarkTask* task) {
41 oop obj = task->obj();
42
43 shenandoah_assert_not_forwarded(NULL, obj);
44 shenandoah_assert_marked(NULL, obj);
45 shenandoah_assert_not_in_cset_except(NULL, obj, _heap->cancelled_gc());
46
47 if (task->is_not_chunked()) {
48 if (obj->is_instance()) {
49 // Case 1: Normal oop, process as usual.
50 obj->oop_iterate(cl);
51 } else if (obj->is_objArray()) {
52 // Case 2: Object array instance and no chunk is set. Must be the first
53 // time we visit it, start the chunked processing.
54 do_chunked_array_start<T>(q, cl, obj);
55 } else {
56 // Case 3: Primitive array. Do nothing, no oops there. We use the same
57 // performance tweak TypeArrayKlass::oop_oop_iterate_impl is using:
58 // We skip iterating over the klass pointer since we know that
59 // Universe::TypeArrayKlass never moves.
60 assert (obj->is_typeArray(), "should be type array");
61 }
62 // Count liveness the last: push the outstanding work to the queues first
63 count_liveness(live_data, obj);
64 } else {
65 // Case 4: Array chunk, has sensible chunk id. Process it.
66 do_chunked_array<T>(q, cl, obj, task->chunk(), task->pow());
67 }
68 }
69
70 inline void ShenandoahConcurrentMark::count_liveness(ShenandoahLiveData* live_data, oop obj) {
71 size_t region_idx = _heap->heap_region_index_containing(obj);
72 ShenandoahHeapRegion* region = _heap->get_region(region_idx);
73 size_t size = obj->size();
74
75 if (!region->is_humongous_start()) {
76 assert(!region->is_humongous(), "Cannot have continuations here");
77 ShenandoahLiveData cur = live_data[region_idx];
78 size_t new_val = size + cur;
79 if (new_val >= SHENANDOAH_LIVEDATA_MAX) {
80 // overflow, flush to region data
81 region->increase_live_data_gc_words(new_val);
82 live_data[region_idx] = 0;
83 } else {
84 // still good, remember in locals
85 live_data[region_idx] = (ShenandoahLiveData) new_val;
86 }
87 } else {
88 shenandoah_assert_in_correct_region(NULL, obj);
89 size_t num_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
90
91 for (size_t i = region_idx; i < region_idx + num_regions; i++) {
92 ShenandoahHeapRegion* chain_reg = _heap->get_region(i);
93 assert(chain_reg->is_humongous(), "Expecting a humongous region");
94 chain_reg->increase_live_data_gc_words(chain_reg->used() >> LogHeapWordSize);
95 }
96 }
97 }
98
99 template <class T>
100 inline void ShenandoahConcurrentMark::do_chunked_array_start(ShenandoahObjToScanQueue* q, T* cl, oop obj) {
101 assert(obj->is_objArray(), "expect object array");
102 objArrayOop array = objArrayOop(obj);
103 int len = array->length();
104
105 if (len <= (int) ObjArrayMarkingStride*2) {
106 // A few slices only, process directly
107 array->oop_iterate_range(cl, 0, len);
108 } else {
109 int bits = log2_long(len);
110 // Compensate for non-power-of-two arrays, cover the array in excess:
111 if (len != (1 << bits)) bits++;
112
113 // Only allow full chunks on the queue. This frees do_chunked_array() from checking from/to
114 // boundaries against array->length(), touching the array header on every chunk.
115 //
116 // To do this, we cut the prefix in full-sized chunks, and submit them on the queue.
117 // If the array is not divided in chunk sizes, then there would be an irregular tail,
118 // which we will process separately.
119
120 int last_idx = 0;
121
122 int chunk = 1;
123 int pow = bits;
124
125 // Handle overflow
126 if (pow >= 31) {
127 assert (pow == 31, "sanity");
128 pow--;
129 chunk = 2;
130 last_idx = (1 << pow);
131 bool pushed = q->push(ShenandoahMarkTask(array, 1, pow));
132 assert(pushed, "overflow queue should always succeed pushing");
133 }
134
135 // Split out tasks, as suggested in ShenandoahMarkTask docs. Record the last
136 // successful right boundary to figure out the irregular tail.
137 while ((1 << pow) > (int)ObjArrayMarkingStride &&
138 (chunk*2 < ShenandoahMarkTask::chunk_size())) {
139 pow--;
140 int left_chunk = chunk*2 - 1;
141 int right_chunk = chunk*2;
142 int left_chunk_end = left_chunk * (1 << pow);
143 if (left_chunk_end < len) {
144 bool pushed = q->push(ShenandoahMarkTask(array, left_chunk, pow));
145 assert(pushed, "overflow queue should always succeed pushing");
146 chunk = right_chunk;
147 last_idx = left_chunk_end;
148 } else {
149 chunk = left_chunk;
150 }
151 }
152
153 // Process the irregular tail, if present
154 int from = last_idx;
155 if (from < len) {
156 array->oop_iterate_range(cl, from, len);
157 }
158 }
159 }
160
161 template <class T>
162 inline void ShenandoahConcurrentMark::do_chunked_array(ShenandoahObjToScanQueue* q, T* cl, oop obj, int chunk, int pow) {
163 assert(obj->is_objArray(), "expect object array");
164 objArrayOop array = objArrayOop(obj);
165
166 assert (ObjArrayMarkingStride > 0, "sanity");
167
168 // Split out tasks, as suggested in ShenandoahMarkTask docs. Avoid pushing tasks that
169 // are known to start beyond the array.
170 while ((1 << pow) > (int)ObjArrayMarkingStride && (chunk*2 < ShenandoahMarkTask::chunk_size())) {
171 pow--;
172 chunk *= 2;
173 bool pushed = q->push(ShenandoahMarkTask(array, chunk - 1, pow));
174 assert(pushed, "overflow queue should always succeed pushing");
175 }
176
177 int chunk_size = 1 << pow;
178
179 int from = (chunk - 1) * chunk_size;
180 int to = chunk * chunk_size;
181
182 #ifdef ASSERT
183 int len = array->length();
184 assert (0 <= from && from < len, err_msg("from is sane: %d/%d", from, len));
185 assert (0 < to && to <= len, err_msg("to is sane: %d/%d", to, len));
186 #endif
187
188 array->oop_iterate_range(cl, from, to);
189 }
190
191 class ShenandoahSATBBufferClosure : public SATBBufferClosure {
192 private:
193 ShenandoahObjToScanQueue* _queue;
194 ShenandoahStrDedupQueue* _dedup_queue;
195 ShenandoahHeap* _heap;
196 ShenandoahMarkingContext* const _mark_context;
197 public:
198 ShenandoahSATBBufferClosure(ShenandoahObjToScanQueue* q, ShenandoahStrDedupQueue* dq) :
199 _queue(q),
200 _dedup_queue(dq),
201 _heap(ShenandoahHeap::heap()),
202 _mark_context(_heap->marking_context())
203 {
204 }
205
206 void do_buffer(void **buffer, size_t size) {
207 assert(size == 0 || !_heap->has_forwarded_objects(), "Forwarded objects are not expected here");
208 if (ShenandoahStringDedup::is_enabled()) {
209 do_buffer_impl<ENQUEUE_DEDUP>(buffer, size);
210 } else {
211 do_buffer_impl<NO_DEDUP>(buffer, size);
212 }
213 }
214
215 template<StringDedupMode STRING_DEDUP>
216 void do_buffer_impl(void **buffer, size_t size) {
217 for (size_t i = 0; i < size; ++i) {
218 oop *p = (oop *) &buffer[i];
219 ShenandoahConcurrentMark::mark_through_ref<oop, NONE, STRING_DEDUP>(p, _heap, _queue, _mark_context, _dedup_queue);
220 }
221 }
222 };
223
224 template<class T, UpdateRefsMode UPDATE_REFS, StringDedupMode STRING_DEDUP>
225 inline void ShenandoahConcurrentMark::mark_through_ref(T *p, ShenandoahHeap* heap, ShenandoahObjToScanQueue* q, ShenandoahMarkingContext* const mark_context, ShenandoahStrDedupQueue* dq) {
226 T o = oopDesc::load_heap_oop(p);
227 if (! oopDesc::is_null(o)) {
228 oop obj = oopDesc::decode_heap_oop_not_null(o);
229 switch (UPDATE_REFS) {
230 case NONE:
231 break;
232 case RESOLVE:
233 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
234 break;
235 case SIMPLE:
236 // We piggy-back reference updating to the marking tasks.
237 obj = heap->update_with_forwarded_not_null(p, obj);
238 break;
239 case CONCURRENT:
240 obj = heap->maybe_update_with_forwarded_not_null(p, obj);
241 break;
242 default:
243 ShouldNotReachHere();
244 }
245
246 // Note: Only when concurrently updating references can obj be different
247 // (that is, really different, not just different from-/to-space copies of the same)
248 // from the one we originally loaded. Mutator thread can beat us by writing something
249 // else into the location. In that case, we would mark through that updated value,
250 // on the off-chance it is not handled by other means (e.g. via SATB). However,
251 // if that write was NULL, we don't need to do anything else.
252 if (UPDATE_REFS != CONCURRENT || !oopDesc::is_null(obj)) {
253 shenandoah_assert_not_forwarded(p, obj);
254 shenandoah_assert_not_in_cset_except(p, obj, heap->cancelled_gc());
255
256 if (mark_context->mark(obj)) {
257 bool pushed = q->push(ShenandoahMarkTask(obj));
258 assert(pushed, "overflow queue should always succeed pushing");
259
260 if ((STRING_DEDUP == ENQUEUE_DEDUP) && ShenandoahStringDedup::is_candidate(obj)) {
261 assert(ShenandoahStringDedup::is_enabled(), "Must be enabled");
262 assert(dq != NULL, "Dedup queue not set");
263 ShenandoahStringDedup::enqueue_candidate(obj, dq);
264 }
265 }
266
267 shenandoah_assert_marked(p, obj);
268 }
269 }
270 }
271
272 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHCONCURRENTMARK_INLINE_HPP