1/*
2 * Copyright (c) 1997, 2019, 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.
22 *
23 */
24
25#ifndef SHARE_RUNTIME_FLAGS_FLAGSETTING_HPP
26#define SHARE_RUNTIME_FLAGS_FLAGSETTING_HPP
27
28#include "memory/allocation.hpp"
29
30// debug flags control various aspects of the VM and are global accessible
31
32// use FlagSetting to temporarily change some debug flag
33// e.g. FlagSetting fs(DebugThisAndThat, true);
34// restored to previous value upon leaving scope
35class FlagSetting : public StackObj {
36 bool val;
37 bool* flag;
38public:
39 FlagSetting(bool& fl, bool newValue) { flag = &fl; val = fl; fl = newValue; }
40 ~FlagSetting() { *flag = val; }
41};
42
43class UIntFlagSetting : public StackObj {
44 uint val;
45 uint* flag;
46public:
47 UIntFlagSetting(uint& fl, uint newValue) { flag = &fl; val = fl; fl = newValue; }
48 ~UIntFlagSetting() { *flag = val; }
49};
50
51class SizeTFlagSetting : public StackObj {
52 size_t val;
53 size_t* flag;
54public:
55 SizeTFlagSetting(size_t& fl, size_t newValue) { flag = &fl; val = fl; fl = newValue; }
56 ~SizeTFlagSetting() { *flag = val; }
57};
58
59// Helper class for temporarily saving the value of a flag during a scope.
60template <size_t SIZE>
61class FlagGuard {
62 unsigned char _value[SIZE];
63 void* const _addr;
64public:
65 FlagGuard(void* flag_addr) : _addr(flag_addr) { memcpy(_value, _addr, SIZE); }
66 ~FlagGuard() { memcpy(_addr, _value, SIZE); }
67};
68
69#define FLAG_GUARD(f) FlagGuard<sizeof(f)> f ## _guard(&f)
70
71#endif // SHARE_RUNTIME_FLAGS_FLAGSETTING_HPP
72