Thu, 07 Apr 2011 09:53:20 -0700
7009266: G1: assert(obj->is_oop_or_null(true )) failed: Error
Summary: A referent object that is only weakly reachable at the start of concurrent marking but is re-attached to the strongly reachable object graph during marking may not be marked as live. This can cause the reference object to be processed prematurely and leave dangling pointers to the referent object. Implement a read barrier for the java.lang.ref.Reference::referent field by intrinsifying the Reference.get() method, and intercepting accesses though JNI, reflection, and Unsafe, so that when a non-null referent object is read it is also logged in an SATB buffer.
Reviewed-by: kvn, iveresov, never, tonyp, dholmes
1 /*
2 * copyright (c) 2011, 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
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23 */
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSET_INLINE_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSET_INLINE_HPP
28 #include "gc_implementation/g1/heapRegionSet.hpp"
30 //////////////////// HeapRegionSetBase ////////////////////
32 inline void HeapRegionSetBase::update_for_addition(HeapRegion* hr) {
33 // Assumes the caller has already verified the region.
35 _length += 1;
36 if (!hr->isHumongous()) {
37 _region_num += 1;
38 } else {
39 _region_num += calculate_region_num(hr);
40 }
41 _total_used_bytes += hr->used();
42 }
44 inline void HeapRegionSetBase::add_internal(HeapRegion* hr) {
45 hrs_assert_region_ok(this, hr, NULL);
46 assert(hr->next() == NULL, hrs_ext_msg(this, "should not already be linked"));
48 update_for_addition(hr);
49 hr->set_containing_set(this);
50 }
52 inline void HeapRegionSetBase::update_for_removal(HeapRegion* hr) {
53 // Assumes the caller has already verified the region.
54 assert(_length > 0, hrs_ext_msg(this, "pre-condition"));
55 _length -= 1;
57 size_t region_num_diff;
58 if (!hr->isHumongous()) {
59 region_num_diff = 1;
60 } else {
61 region_num_diff = calculate_region_num(hr);
62 }
63 assert(region_num_diff <= _region_num,
64 hrs_err_msg("[%s] region's region num: "SIZE_FORMAT" "
65 "should be <= region num: "SIZE_FORMAT,
66 name(), region_num_diff, _region_num));
67 _region_num -= region_num_diff;
69 size_t used_bytes = hr->used();
70 assert(used_bytes <= _total_used_bytes,
71 hrs_err_msg("[%s] region's used bytes: "SIZE_FORMAT" "
72 "should be <= used bytes: "SIZE_FORMAT,
73 name(), used_bytes, _total_used_bytes));
74 _total_used_bytes -= used_bytes;
75 }
77 inline void HeapRegionSetBase::remove_internal(HeapRegion* hr) {
78 hrs_assert_region_ok(this, hr, this);
79 assert(hr->next() == NULL, hrs_ext_msg(this, "should already be unlinked"));
81 hr->set_containing_set(NULL);
82 update_for_removal(hr);
83 }
85 //////////////////// HeapRegionSet ////////////////////
87 inline void HeapRegionSet::add(HeapRegion* hr) {
88 hrs_assert_mt_safety_ok(this);
89 // add_internal() will verify the region.
90 add_internal(hr);
91 }
93 inline void HeapRegionSet::remove(HeapRegion* hr) {
94 hrs_assert_mt_safety_ok(this);
95 // remove_internal() will verify the region.
96 remove_internal(hr);
97 }
99 inline void HeapRegionSet::remove_with_proxy(HeapRegion* hr,
100 HeapRegionSet* proxy_set) {
101 // No need to fo the MT safety check here given that this method
102 // does not update the contents of the set but instead accumulates
103 // the changes in proxy_set which is assumed to be thread-local.
104 hrs_assert_sets_match(this, proxy_set);
105 hrs_assert_region_ok(this, hr, this);
107 hr->set_containing_set(NULL);
108 proxy_set->update_for_addition(hr);
109 }
111 //////////////////// HeapRegionLinkedList ////////////////////
113 inline void HeapRegionLinkedList::add_as_head(HeapRegion* hr) {
114 hrs_assert_mt_safety_ok(this);
115 assert((length() == 0 && _head == NULL && _tail == NULL) ||
116 (length() > 0 && _head != NULL && _tail != NULL),
117 hrs_ext_msg(this, "invariant"));
118 // add_internal() will verify the region.
119 add_internal(hr);
121 // Now link the region.
122 if (_head != NULL) {
123 hr->set_next(_head);
124 } else {
125 _tail = hr;
126 }
127 _head = hr;
128 }
130 inline void HeapRegionLinkedList::add_as_tail(HeapRegion* hr) {
131 hrs_assert_mt_safety_ok(this);
132 assert((length() == 0 && _head == NULL && _tail == NULL) ||
133 (length() > 0 && _head != NULL && _tail != NULL),
134 hrs_ext_msg(this, "invariant"));
135 // add_internal() will verify the region.
136 add_internal(hr);
138 // Now link the region.
139 if (_tail != NULL) {
140 _tail->set_next(hr);
141 } else {
142 _head = hr;
143 }
144 _tail = hr;
145 }
147 inline HeapRegion* HeapRegionLinkedList::remove_head() {
148 hrs_assert_mt_safety_ok(this);
149 assert(!is_empty(), hrs_ext_msg(this, "the list should not be empty"));
150 assert(length() > 0 && _head != NULL && _tail != NULL,
151 hrs_ext_msg(this, "invariant"));
153 // We need to unlink it first.
154 HeapRegion* hr = _head;
155 _head = hr->next();
156 if (_head == NULL) {
157 _tail = NULL;
158 }
159 hr->set_next(NULL);
161 // remove_internal() will verify the region.
162 remove_internal(hr);
163 return hr;
164 }
166 inline HeapRegion* HeapRegionLinkedList::remove_head_or_null() {
167 hrs_assert_mt_safety_ok(this);
169 if (!is_empty()) {
170 return remove_head();
171 } else {
172 return NULL;
173 }
174 }
176 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSET_INLINE_HPP