prefetch.hpp revision 1879:f95d63e2154a 
1/*
2 * Copyright (c) 2003, 2010, 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
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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 *
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24
25#ifndef SHARE_VM_RUNTIME_PREFETCH_HPP
26#define SHARE_VM_RUNTIME_PREFETCH_HPP
27
28#include "memory/allocation.hpp"
29
30// If calls to prefetch methods are in a loop, the loop should be cloned
31// such that if Prefetch{Scan,Copy}Interval and/or PrefetchFieldInterval
32// say not to do prefetching, these methods aren't called.  At the very
33// least, they take up a memory issue slot.  They should be implemented
34// as inline assembly code: doing an actual call isn't worth the cost.
35
36class Prefetch : AllStatic {
37 public:
38  enum style {
39    do_none,  // Do no prefetching
40    do_read,  // Do read prefetching
41    do_write  // Do write prefetching
42  };
43
44  // Prefetch anticipating read; must not fault, semantically a no-op
45  static void read(void* loc, intx interval);
46
47  // Prefetch anticipating write; must not fault, semantically a no-op
48  static void write(void* loc, intx interval);
49};
50
51#endif // SHARE_VM_RUNTIME_PREFETCH_HPP
52