1 /*

     2  * Copyright (c) 2000, 2014, 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 #include "precompiled.hpp"

    26 #include "memory/allocation.hpp"

    27 #include "memory/allocation.inline.hpp"

    28 #include "memory/memRegion.hpp"

    29 #include "runtime/globals.hpp"

    30 

    31 // A very simple data structure representing a contigous word-aligned

    32 // region of address space.

    33 

    34 MemRegion MemRegion::intersection(const MemRegion mr2) const {

    35   MemRegion res;

    36   HeapWord* res_start = MAX2(start(), mr2.start());

    37   HeapWord* res_end   = MIN2(end(),   mr2.end());

    38   if (res_start < res_end) {

    39     res.set_start(res_start);

    40     res.set_end(res_end);

    41   }

    42   return res;

    43 }

    44 

    45 MemRegion MemRegion::_union(const MemRegion mr2) const {

    46   // If one region is empty, return the other

    47   if (is_empty()) return mr2;

    48   if (mr2.is_empty()) return MemRegion(start(), end());

    49 

    50   // Otherwise, regions must overlap or be adjacent

    51   assert(((start() <= mr2.start()) && (end() >= mr2.start())) ||

    52          ((mr2.start() <= start()) && (mr2.end() >= start())),

    53              "non-adjacent or overlapping regions");

    54   MemRegion res;

    55   HeapWord* res_start = MIN2(start(), mr2.start());

    56   HeapWord* res_end   = MAX2(end(),   mr2.end());

    57   res.set_start(res_start);

    58   res.set_end(res_end);

    59   return res;

    60 }

    61 

    62 MemRegion MemRegion::minus(const MemRegion mr2) const {

    63   // There seem to be 6 cases:

    64   //                  |this MemRegion|

    65   // |strictly below|

    66   //   |overlap beginning|

    67   //                    |interior|

    68   //                        |overlap ending|

    69   //                                   |strictly above|

    70   //              |completely overlapping|

    71   // We can't deal with an interior case because it would

    72   // produce two disjoint regions as a result.

    73   // We aren't trying to be optimal in the number of tests below,

    74   // but the order is important to distinguish the strictly cases

    75   // from the overlapping cases.

    76   if (mr2.end() <= start()) {

    77     // strictly below

    78     return MemRegion(start(), end());

    79   }

    80   if (mr2.start() <= start() && mr2.end() <= end()) {

    81     // overlap beginning

    82     return MemRegion(mr2.end(), end());

    83   }

    84   if (mr2.start() >= end()) {

    85     // strictly above

    86     return MemRegion(start(), end());

    87   }

    88   if (mr2.start() >= start() && mr2.end() >= end()) {

    89     // overlap ending

    90     return MemRegion(start(), mr2.start());

    91   }

    92   if (mr2.start() <= start() && mr2.end() >= end()) {

    93     // completely overlapping

    94     return MemRegion();

    95   }

    96   if (mr2.start() > start() && mr2.end() < end()) {

    97     // interior

    98     guarantee(false, "MemRegion::minus, but interior");

    99     return MemRegion();

   100   }

   101   ShouldNotReachHere();

   102   return MemRegion();

   103 }

   104 

   105 void* MemRegion::operator new(size_t size) throw() {

   106   return (address)AllocateHeap(size, mtGC, CURRENT_PC,

   107     AllocFailStrategy::RETURN_NULL);

   108 }

   109 

   110 void* MemRegion::operator new [](size_t size) throw() {

   111   return (address)AllocateHeap(size, mtGC, CURRENT_PC,

   112     AllocFailStrategy::RETURN_NULL);

   113 }

   114 void  MemRegion::operator delete(void* p) {

   115   FreeHeap(p);

   116 }

   117 

   118 void  MemRegion::operator delete [](void* p) {

   119   FreeHeap(p);

   120 }

   121