1 /*
2 * Copyright (c) 2014, Oracle and/or its affiliates. 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.
18 *
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
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1PARSCANTHREADSTATE_INLINE_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1PARSCANTHREADSTATE_INLINE_HPP
27
28 #include "gc_implementation/g1/g1ParScanThreadState.hpp"
29 #include "gc_implementation/g1/g1RemSet.inline.hpp"
30 #include "oops/oop.inline.hpp"
31
32 template <class T> inline void G1ParScanThreadState::immediate_rs_update(HeapRegion* from, T* p, int tid) {
33 if (!from->is_survivor()) {
34 _g1_rem->par_write_ref(from, p, tid);
35 }
36 }
37
38 template <class T> void G1ParScanThreadState::update_rs(HeapRegion* from, T* p, int tid) {
39 if (G1DeferredRSUpdate) {
40 deferred_rs_update(from, p, tid);
41 } else {
42 immediate_rs_update(from, p, tid);
43 }
44 }
45
46 template <class T> void G1ParScanThreadState::do_oop_evac(T* p, HeapRegion* from) {
47 assert(!oopDesc::is_null(oopDesc::load_decode_heap_oop(p)),
48 "Reference should not be NULL here as such are never pushed to the task queue.");
49 oop obj = oopDesc::load_decode_heap_oop_not_null(p);
50
51 // Although we never intentionally push references outside of the collection
52 // set, due to (benign) races in the claim mechanism during RSet scanning more
53 // than one thread might claim the same card. So the same card may be
54 // processed multiple times. So redo this check.
55 if (_g1h->is_in_cset_or_humongous(obj)) {
56 oop forwardee;
57 if (obj->is_forwarded()) {
58 forwardee = obj->forwardee();
59 } else {
60 forwardee = copy_to_survivor_space(obj);
61 }
62 if (forwardee != NULL) {
63 oopDesc::encode_store_heap_oop(p, forwardee);
64 }
65 }
66
67 assert(obj != NULL, "Must be");
68 update_rs(from, p, queue_num());
69 }
70
71 inline void G1ParScanThreadState::do_oop_partial_array(oop* p) {
72 assert(has_partial_array_mask(p), "invariant");
73 oop from_obj = clear_partial_array_mask(p);
74
75 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
76 assert(from_obj->is_objArray(), "must be obj array");
77 objArrayOop from_obj_array = objArrayOop(from_obj);
78 // The from-space object contains the real length.
79 int length = from_obj_array->length();
80
81 assert(from_obj->is_forwarded(), "must be forwarded");
82 oop to_obj = from_obj->forwardee();
83 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
84 objArrayOop to_obj_array = objArrayOop(to_obj);
85 // We keep track of the next start index in the length field of the
86 // to-space object.
87 int next_index = to_obj_array->length();
88 assert(0 <= next_index && next_index < length,
89 err_msg("invariant, next index: %d, length: %d", next_index, length));
90
91 int start = next_index;
92 int end = length;
93 int remainder = end - start;
94 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
95 if (remainder > 2 * ParGCArrayScanChunk) {
96 end = start + ParGCArrayScanChunk;
97 to_obj_array->set_length(end);
98 // Push the remainder before we process the range in case another
99 // worker has run out of things to do and can steal it.
100 oop* from_obj_p = set_partial_array_mask(from_obj);
101 push_on_queue(from_obj_p);
102 } else {
103 assert(length == end, "sanity");
104 // We'll process the final range for this object. Restore the length
105 // so that the heap remains parsable in case of evacuation failure.
106 to_obj_array->set_length(end);
107 }
108 _scanner.set_region(_g1h->heap_region_containing_raw(to_obj));
109 // Process indexes [start,end). It will also process the header
110 // along with the first chunk (i.e., the chunk with start == 0).
111 // Note that at this point the length field of to_obj_array is not
112 // correct given that we are using it to keep track of the next
113 // start index. oop_iterate_range() (thankfully!) ignores the length
114 // field and only relies on the start / end parameters. It does
115 // however return the size of the object which will be incorrect. So
116 // we have to ignore it even if we wanted to use it.
117 to_obj_array->oop_iterate_range(&_scanner, start, end);
118 }
119
120 template <class T> inline void G1ParScanThreadState::deal_with_reference(T* ref_to_scan) {
121 if (!has_partial_array_mask(ref_to_scan)) {
122 // Note: we can use "raw" versions of "region_containing" because
123 // "obj_to_scan" is definitely in the heap, and is not in a
124 // humongous region.
125 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
126 do_oop_evac(ref_to_scan, r);
127 } else {
128 do_oop_partial_array((oop*)ref_to_scan);
129 }
130 }
131
132 inline void G1ParScanThreadState::dispatch_reference(StarTask ref) {
133 assert(verify_task(ref), "sanity");
134 if (ref.is_narrow()) {
135 deal_with_reference((narrowOop*)ref);
136 } else {
137 deal_with_reference((oop*)ref);
138 }
139 }
140
141 void G1ParScanThreadState::steal_and_trim_queue(RefToScanQueueSet *task_queues) {
142 StarTask stolen_task;
143 while (task_queues->steal(queue_num(), hash_seed(), stolen_task)) {
144 assert(verify_task(stolen_task), "sanity");
145 dispatch_reference(stolen_task);
146
147 // We've just processed a reference and we might have made
148 // available new entries on the queues. So we have to make sure
149 // we drain the queues as necessary.
150 trim_queue();
151 }
152 }
153
154 #endif /* SHARE_VM_GC_IMPLEMENTATION_G1_G1PARSCANTHREADSTATE_INLINE_HPP */
155