1/*
2 * Copyright (c) 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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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22 */
23
24#ifndef SHARE_GC_SHARED_GCTHREADLOCALDATA_HPP
25#define SHARE_GC_SHARED_GCTHREADLOCALDATA_HPP
26
27#include "utilities/globalDefinitions.hpp"
28
29// Thread local data area for GC-specific information. Each GC
30// is free to decide the internal structure and contents of this
31// area. It is represented as a 64-bit aligned opaque blob to
32// avoid circular dependencies between Thread and all GCs. For
33// the same reason, the size of the data area is hard coded to
34// provide enough space for all current GCs. Adjust the size if
35// needed, but avoid making it excessively large as it adds to
36// the memory overhead of creating a thread.
37//
38// Use Thread::gc_data<T>() to access the data, where T is the
39// GC-specific type describing the structure of the data. GCs
40// should consider placing frequently accessed fields first in
41// T, so that field offsets relative to Thread are small, which
42// often allows for a more compact instruction encoding.
43typedef uint64_t GCThreadLocalData[18]; // 144 bytes
44
45#endif // SHARE_GC_SHARED_GCTHREADLOCALDATA_HPP
46