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