1 /*
2 * Copyright (c) 2002, 2015, 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 #include "precompiled.hpp"
26 #include "gc/parallel/mutableSpace.hpp"
27 #include "gc/parallel/parallelScavengeHeap.hpp"
28 #include "gc/parallel/psPromotionLAB.hpp"
29 #include "oops/oop.inline.hpp"
30
31 size_t PSPromotionLAB::filler_header_size;
32
33 // This is the shared initialization code. It sets up the basic pointers,
34 // and allows enough extra space for a filler object. We call a virtual
35 // method, "lab_is_valid()" to handle the different asserts the old/young
36 // labs require.
37 void PSPromotionLAB::initialize(MemRegion lab) {
38 assert(lab_is_valid(lab), "Sanity");
39
40 HeapWord* bottom = lab.start();
41 HeapWord* end = lab.end();
42
43 set_bottom(bottom);
44 set_end(end);
45 set_top(bottom);
46
47 // Initialize after VM starts up because header_size depends on compressed
48 // oops.
49 filler_header_size = align_object_size(typeArrayOopDesc::header_size(T_INT));
50
51 // We can be initialized to a zero size!
52 if (free() > 0) {
53 if (ZapUnusedHeapArea) {
54 debug_only(Copy::fill_to_words(top(), free()/HeapWordSize, badHeapWord));
55 }
56
57 // NOTE! We need to allow space for a filler object.
58 assert(lab.word_size() >= filler_header_size, "lab is too small");
59 end = end - filler_header_size;
60 set_end(end);
61
62 _state = needs_flush;
63 } else {
64 _state = zero_size;
65 }
66
67 assert(this->top() <= this->end(), "pointers out of order");
68 }
69
70 // Fill all remaining lab space with an unreachable object.
71 // The goal is to leave a contiguous parseable span of objects.
72 void PSPromotionLAB::flush() {
73 assert(_state != flushed, "Attempt to flush PLAB twice");
74 assert(top() <= end(), "pointers out of order");
75
76 // If we were initialized to a zero sized lab, there is
77 // nothing to flush
78 if (_state == zero_size)
79 return;
80
81 // PLAB's never allocate the last aligned_header_size
82 // so they can always fill with an array.
83 HeapWord* tlab_end = end() + filler_header_size;
84 typeArrayOop filler_oop = (typeArrayOop) top();
85 filler_oop->set_mark(markOopDesc::prototype());
86 filler_oop->set_klass(Universe::intArrayKlassObj());
87 const size_t array_length =
88 pointer_delta(tlab_end, top()) - typeArrayOopDesc::header_size(T_INT);
89 assert( (array_length * (HeapWordSize/sizeof(jint))) < (size_t)max_jint, "array too big in PSPromotionLAB");
90 filler_oop->set_length((int)(array_length * (HeapWordSize/sizeof(jint))));
91
92 #ifdef ASSERT
93 // Note that we actually DO NOT want to use the aligned header size!
94 HeapWord* elt_words = ((HeapWord*)filler_oop) + typeArrayOopDesc::header_size(T_INT);
95 Copy::fill_to_words(elt_words, array_length, 0xDEAABABE);
96 #endif
97
98 set_bottom(NULL);
99 set_end(NULL);
100 set_top(NULL);
101
102 _state = flushed;
103 }
104
105 bool PSPromotionLAB::unallocate_object(HeapWord* obj, size_t obj_size) {
106 assert(ParallelScavengeHeap::heap()->is_in(obj), "Object outside heap");
107
108 if (contains(obj)) {
109 HeapWord* object_end = obj + obj_size;
110 assert(object_end == top(), "Not matching last allocation");
111
112 set_top(obj);
113 return true;
114 }
115
116 return false;
117 }
118
119 // Fill all remaining lab space with an unreachable object.
120 // The goal is to leave a contiguous parseable span of objects.
121 void PSOldPromotionLAB::flush() {
122 assert(_state != flushed, "Attempt to flush PLAB twice");
123 assert(top() <= end(), "pointers out of order");
124
125 if (_state == zero_size)
126 return;
127
128 HeapWord* obj = top();
129
130 PSPromotionLAB::flush();
131
132 assert(_start_array != NULL, "Sanity");
133
134 _start_array->allocate_block(obj);
135 }
136
137 #ifdef ASSERT
138
139 bool PSYoungPromotionLAB::lab_is_valid(MemRegion lab) {
140 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
141 MutableSpace* to_space = heap->young_gen()->to_space();
142 MemRegion used = to_space->used_region();
143 if (used.contains(lab)) {
144 return true;
145 }
146
147 return false;
148 }
149
150 bool PSOldPromotionLAB::lab_is_valid(MemRegion lab) {
151 assert(_start_array->covered_region().contains(lab), "Sanity");
152
153 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
154 PSOldGen* old_gen = heap->old_gen();
155 MemRegion used = old_gen->object_space()->used_region();
156
157 if (used.contains(lab)) {
158 return true;
159 }
160
161 return false;
162 }
163
164 #endif /* ASSERT */