1 /*
2 * Copyright (c) 2002, 2018, 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 "memory/universe.hpp"
30 #include "oops/oop.inline.hpp"
31
32 size_t PSPromotionLAB::filler_header_size;
33
34 // This is the shared initialization code. It sets up the basic pointers,
35 // and allows enough extra space for a filler object. We call a virtual
36 // method, "lab_is_valid()" to handle the different asserts the old/young
37 // labs require.
38 void PSPromotionLAB::initialize(MemRegion lab) {
39 assert(lab_is_valid(lab), "Sanity");
40
41 HeapWord* bottom = lab.start();
42 HeapWord* end = lab.end();
43
44 set_bottom(bottom);
45 set_end(end);
46 set_top(bottom);
47
48 // Initialize after VM starts up because header_size depends on compressed
49 // oops.
50 filler_header_size = align_object_size((arrayOopDesc::base_offset_in_bytes(T_INT) + BytesPerWord) / BytesPerWord);
51
52 // We can be initialized to a zero size!
53 if (free() > 0) {
54 if (ZapUnusedHeapArea) {
55 debug_only(Copy::fill_to_words(top(), free()/HeapWordSize, badHeapWord));
56 }
57
58 // NOTE! We need to allow space for a filler object.
59 assert(lab.word_size() >= filler_header_size, "lab is too small");
60 end = end - filler_header_size;
61 set_end(end);
62
63 _state = needs_flush;
64 } else {
65 _state = zero_size;
66 }
67
68 assert(this->top() <= this->end(), "pointers out of order");
69 }
70
71 // Fill all remaining lab space with an unreachable object.
72 // The goal is to leave a contiguous parseable span of objects.
73 void PSPromotionLAB::flush() {
74 assert(_state != flushed, "Attempt to flush PLAB twice");
75 assert(top() <= end(), "pointers out of order");
76
77 // If we were initialized to a zero sized lab, there is
78 // nothing to flush
79 if (_state == zero_size)
80 return;
81
82 // PLAB's never allocate the last aligned_header_size
83 // so they can always fill with an array.
84 HeapWord* tlab_end = end() + filler_header_size;
85 typeArrayOop filler_oop = (typeArrayOop) cast_to_oop(top());
86 if (UseCompactObjectHeaders) {
87 filler_oop->set_mark(Universe::intArrayKlassObj()->prototype_header());
88 } else {
89 filler_oop->set_mark(markWord::prototype());
90 filler_oop->set_klass(Universe::intArrayKlassObj());
91 }
92 int header_size = arrayOopDesc::base_offset_in_bytes(T_INT);
93 const size_t array_length_bytes = pointer_delta(tlab_end, top(), 1) - header_size;
94 assert((array_length_bytes / sizeof(jint)) < (size_t)max_jint, "array too big in PSPromotionLAB");
95 filler_oop->set_length((int)(array_length_bytes / sizeof(jint)));
96
97 #ifdef ASSERT
98 // Note that we actually DO NOT want to use the aligned header size!
99 const size_t array_length_words = pointer_delta(tlab_end, top()) - heap_word_size(header_size);
100 HeapWord* elt_words = cast_from_oop<HeapWord*>(filler_oop) + heap_word_size(header_size);
101 Copy::fill_to_words(elt_words, array_length_words, 0xDEAABABE);
102 #endif
103
104 set_bottom(NULL);
105 set_end(NULL);
106 set_top(NULL);
107
108 _state = flushed;
109 }
110
111 bool PSPromotionLAB::unallocate_object(HeapWord* obj, size_t obj_size) {
112 assert(ParallelScavengeHeap::heap()->is_in(obj), "Object outside heap");
113
114 if (contains(obj)) {
115 HeapWord* object_end = obj + obj_size;
116 assert(object_end == top(), "Not matching last allocation");
117
118 set_top(obj);
119 return true;
120 }
121
122 return false;
123 }
124
125 // Fill all remaining lab space with an unreachable object.
126 // The goal is to leave a contiguous parseable span of objects.
127 void PSOldPromotionLAB::flush() {
128 assert(_state != flushed, "Attempt to flush PLAB twice");
129 assert(top() <= end(), "pointers out of order");
130
131 if (_state == zero_size)
132 return;
133
134 HeapWord* obj = top();
135
136 PSPromotionLAB::flush();
137
138 assert(_start_array != NULL, "Sanity");
139
140 _start_array->allocate_block(obj);
141 }
142
143 #ifdef ASSERT
144
145 bool PSYoungPromotionLAB::lab_is_valid(MemRegion lab) {
146 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
147 MutableSpace* to_space = heap->young_gen()->to_space();
148 MemRegion used = to_space->used_region();
149 if (used.contains(lab)) {
150 return true;
151 }
152
153 return false;
154 }
155
156 bool PSOldPromotionLAB::lab_is_valid(MemRegion lab) {
157 assert(_start_array->covered_region().contains(lab), "Sanity");
158
159 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
160 PSOldGen* old_gen = heap->old_gen();
161 MemRegion used = old_gen->object_space()->used_region();
162
163 if (used.contains(lab)) {
164 return true;
165 }
166
167 return false;
168 }
169
170 #endif /* ASSERT */