freeChunk.cpp revision 8413:92457dfb91bd 
1/*
2 * Copyright (c) 2001, 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/cms/freeChunk.hpp"
27#include "memory/freeBlockDictionary.hpp"
28#include "utilities/copy.hpp"
29
30#ifndef PRODUCT
31
32#define baadbabeHeapWord badHeapWordVal
33#define deadbeefHeapWord 0xdeadbeef
34
35size_t const FreeChunk::header_size() {
36  return sizeof(FreeChunk)/HeapWordSize;
37}
38
39void FreeChunk::mangleAllocated(size_t size) {
40  // mangle all but the header of a just-allocated block
41  // of storage
42  assert(size >= MinChunkSize, "smallest size of object");
43  // we can't assert that _size == size because this may be an
44  // allocation out of a linear allocation block
45  assert(sizeof(FreeChunk) % HeapWordSize == 0,
46         "shouldn't write beyond chunk");
47  HeapWord* addr = (HeapWord*)this;
48  size_t hdr = header_size();
49  Copy::fill_to_words(addr + hdr, size - hdr, baadbabeHeapWord);
50}
51
52void FreeChunk::mangleFreed(size_t sz) {
53  assert(baadbabeHeapWord != deadbeefHeapWord, "Need distinct patterns");
54  // mangle all but the header of a just-freed block of storage
55  // just prior to passing it to the storage dictionary
56  assert(sz >= MinChunkSize, "smallest size of object");
57  assert(sz == size(), "just checking");
58  HeapWord* addr = (HeapWord*)this;
59  size_t hdr = header_size();
60  Copy::fill_to_words(addr + hdr, sz - hdr, deadbeefHeapWord);
61}
62
63void FreeChunk::verifyList() const {
64  FreeChunk* nextFC = next();
65  if (nextFC != NULL) {
66    assert(this == nextFC->prev(), "broken chain");
67    assert(size() == nextFC->size(), "wrong size");
68    nextFC->verifyList();
69  }
70}
71#endif
72
73void FreeChunk::print_on(outputStream* st) {
74  st->print_cr("Next: " PTR_FORMAT " Prev: " PTR_FORMAT " %s",
75    p2i(next()), p2i(prev()), cantCoalesce() ? "[can't coalesce]" : "");
76}
77