1 /* 2 * Copyright (c) 1997, 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. 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_VM_RUNTIME_FLAGS_FLAGSETTING_HPP 26 #define SHARE_VM_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 35 class FlagSetting : public StackObj { 36 bool val; 37 bool* flag; 38 public: 39 FlagSetting(bool& fl, bool newValue) { flag = &fl; val = fl; fl = newValue; } 40 ~FlagSetting() { *flag = val; } 41 }; 42 43 class UIntFlagSetting : public StackObj { 44 uint val; 45 uint* flag; 46 public: 47 UIntFlagSetting(uint& fl, uint newValue) { flag = &fl; val = fl; fl = newValue; } 48 ~UIntFlagSetting() { *flag = val; } 49 }; 50 51 class SizeTFlagSetting : public StackObj { 52 size_t val; 53 size_t* flag; 54 public: 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. 60 template <size_t SIZE> 61 class FlagGuard { 62 unsigned char _value[SIZE]; 63 void* const _addr; 64 public: 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_VM_RUNTIME_FLAGS_FLAGSETTING_HPP