1/*
2 * Copyright (c) 2016, 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.
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23 */
24
25#ifndef SHARE_VM_GC_PARALLEL_OBJECTSTARTARRAY_INLINE_HPP
26#define SHARE_VM_GC_PARALLEL_OBJECTSTARTARRAY_INLINE_HPP
27
28#include "gc/parallel/objectStartArray.hpp"
29
30// Optimized for finding the first object that crosses into
31// a given block. The blocks contain the offset of the last
32// object in that block. Scroll backwards by one, and the first
33// object hit should be at the beginning of the block
34HeapWord* ObjectStartArray::object_start(HeapWord* addr) const {
35  assert_covered_region_contains(addr);
36  jbyte* block = block_for_addr(addr);
37  HeapWord* scroll_forward = offset_addr_for_block(block--);
38  while (scroll_forward > addr) {
39    scroll_forward = offset_addr_for_block(block--);
40  }
41
42  HeapWord* next = scroll_forward;
43  while (next <= addr) {
44    scroll_forward = next;
45    next += oop(next)->size();
46  }
47  assert(scroll_forward <= addr, "wrong order for current and arg");
48  assert(addr <= next, "wrong order for arg and next");
49  return scroll_forward;
50}
51
52
53#endif // SHARE_VM_GC_PARALLEL_OBJECTSTARTARRAY_INLINE_HPP
54