psPromotionLAB.cpp revision 8413:92457dfb91bd 
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.
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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 */
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
31size_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.
37void 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.
72void 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
105bool 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.
121void 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
139bool 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
150bool 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 */
165