1 /*
2 * Copyright (c) 2002, 2008, 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 "incls/_precompiled.incl"
26 #include "incls/_psPromotionLAB.cpp.incl"
27
28 size_t PSPromotionLAB::filler_header_size;
29
30 // This is the shared initialization code. It sets up the basic pointers,
31 // and allows enough extra space for a filler object. We call a virtual
32 // method, "lab_is_valid()" to handle the different asserts the old/young
33 // labs require.
34 void PSPromotionLAB::initialize(MemRegion lab) {
35 assert(lab_is_valid(lab), "Sanity");
36
37 HeapWord* bottom = lab.start();
38 HeapWord* end = lab.end();
39
40 set_bottom(bottom);
41 set_end(end);
42 set_top(bottom);
43
44 // Initialize after VM starts up because header_size depends on compressed
45 // oops.
46 filler_header_size = align_object_size(typeArrayOopDesc::header_size(T_INT));
47
48 // We can be initialized to a zero size!
49 if (free() > 0) {
50 if (ZapUnusedHeapArea) {
51 debug_only(Copy::fill_to_words(top(), free()/HeapWordSize, badHeapWord));
52 }
53
54 // NOTE! We need to allow space for a filler object.
55 assert(lab.word_size() >= filler_header_size, "lab is too small");
56 end = end - filler_header_size;
57 set_end(end);
58
59 _state = needs_flush;
60 } else {
61 _state = zero_size;
62 }
63
64 assert(this->top() <= this->end(), "pointers out of order");
65 }
66
67 // Fill all remaining lab space with an unreachable object.
68 // The goal is to leave a contiguous parseable span of objects.
69 void PSPromotionLAB::flush() {
70 assert(_state != flushed, "Attempt to flush PLAB twice");
71 assert(top() <= end(), "pointers out of order");
72
73 // If we were initialized to a zero sized lab, there is
74 // nothing to flush
75 if (_state == zero_size)
76 return;
77
78 // PLAB's never allocate the last aligned_header_size
79 // so they can always fill with an array.
80 HeapWord* tlab_end = end() + filler_header_size;
81 typeArrayOop filler_oop = (typeArrayOop) top();
82 filler_oop->set_mark(markOopDesc::prototype());
83 filler_oop->set_klass(Universe::intArrayKlassObj());
84 const size_t array_length =
85 pointer_delta(tlab_end, top()) - typeArrayOopDesc::header_size(T_INT);
86 assert( (array_length * (HeapWordSize/sizeof(jint))) < (size_t)max_jint, "array too big in PSPromotionLAB");
87 filler_oop->set_length((int)(array_length * (HeapWordSize/sizeof(jint))));
88
89 #ifdef ASSERT
90 // Note that we actually DO NOT want to use the aligned header size!
91 HeapWord* elt_words = ((HeapWord*)filler_oop) + typeArrayOopDesc::header_size(T_INT);
92 Copy::fill_to_words(elt_words, array_length, 0xDEAABABE);
93 #endif
94
95 set_bottom(NULL);
96 set_end(NULL);
97 set_top(NULL);
98
99 _state = flushed;
100 }
101
102 bool PSPromotionLAB::unallocate_object(oop obj) {
103 assert(Universe::heap()->is_in(obj), "Object outside heap");
104
105 if (contains(obj)) {
106 HeapWord* object_end = (HeapWord*)obj + obj->size();
107 assert(object_end <= top(), "Object crosses promotion LAB boundary");
108
109 if (object_end == top()) {
110 set_top((HeapWord*)obj);
111 return true;
112 }
113 }
114
115 return false;
116 }
117
118 // Fill all remaining lab space with an unreachable object.
119 // The goal is to leave a contiguous parseable span of objects.
120 void PSOldPromotionLAB::flush() {
121 assert(_state != flushed, "Attempt to flush PLAB twice");
122 assert(top() <= end(), "pointers out of order");
123
124 if (_state == zero_size)
125 return;
126
127 HeapWord* obj = top();
128
129 PSPromotionLAB::flush();
130
131 assert(_start_array != NULL, "Sanity");
132
133 _start_array->allocate_block(obj);
134 }
135
136 #ifdef ASSERT
137
138 bool PSYoungPromotionLAB::lab_is_valid(MemRegion lab) {
139 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
140 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
141
142 MutableSpace* to_space = heap->young_gen()->to_space();
143 MemRegion used = to_space->used_region();
144 if (used.contains(lab)) {
145 return true;
146 }
147
148 return false;
149 }
150
151 bool PSOldPromotionLAB::lab_is_valid(MemRegion lab) {
152 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
153 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
154 assert(_start_array->covered_region().contains(lab), "Sanity");
155
156 PSOldGen* old_gen = heap->old_gen();
157 MemRegion used = old_gen->object_space()->used_region();
158
159 if (used.contains(lab)) {
160 return true;
161 }
162
163 return false;
164 }
165
166 #endif /* ASSERT */