1/*
2 * Copyright (c) 2000, 2013, 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.
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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
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23 */
24
25#ifndef SHARE_VM_MEMORY_MEMREGION_HPP
26#define SHARE_VM_MEMORY_MEMREGION_HPP
27
28#include "memory/allocation.hpp"
29#include "utilities/debug.hpp"
30#include "utilities/globalDefinitions.hpp"
31
32// A very simple data structure representing a contigous region
33// region of address space.
34
35// Note that MemRegions are passed by value, not by reference.
36// The intent is that they remain very small and contain no
37// objects. _ValueObj should never be allocated in heap but we do
38// create MemRegions (in CardTableModRefBS) in heap so operator
39// new and operator new [] added for this special case.
40
41class MetaWord;
42
43class MemRegion VALUE_OBJ_CLASS_SPEC {
44  friend class VMStructs;
45private:
46  HeapWord* _start;
47  size_t    _word_size;
48
49public:
50  MemRegion() : _start(NULL), _word_size(0) {};
51  MemRegion(HeapWord* start, size_t word_size) :
52    _start(start), _word_size(word_size) {};
53  MemRegion(HeapWord* start, HeapWord* end) :
54    _start(start), _word_size(pointer_delta(end, start)) {
55    assert(end >= start, "incorrect constructor arguments");
56  }
57  MemRegion(MetaWord* start, MetaWord* end) :
58    _start((HeapWord*)start), _word_size(pointer_delta(end, start)) {
59    assert(end >= start, "incorrect constructor arguments");
60  }
61
62  MemRegion(const MemRegion& mr): _start(mr._start), _word_size(mr._word_size) {}
63
64  MemRegion intersection(const MemRegion mr2) const;
65  // regions must overlap or be adjacent
66  MemRegion _union(const MemRegion mr2) const;
67  // minus will fail a guarantee if mr2 is interior to this,
68  // since there's no way to return 2 disjoint regions.
69  MemRegion minus(const MemRegion mr2) const;
70
71  HeapWord* start() const { return _start; }
72  HeapWord* end() const   { return _start + _word_size; }
73  HeapWord* last() const  { return _start + _word_size - 1; }
74
75  void set_start(HeapWord* start) { _start = start; }
76  void set_end(HeapWord* end)     { _word_size = pointer_delta(end, _start); }
77  void set_word_size(size_t word_size) {
78    _word_size = word_size;
79  }
80
81  bool contains(const MemRegion mr2) const {
82    return _start <= mr2._start && end() >= mr2.end();
83  }
84  bool contains(const void* addr) const {
85    return addr >= (void*)_start && addr < (void*)end();
86  }
87  bool equals(const MemRegion mr2) const {
88    // first disjunct since we do not have a canonical empty set
89    return ((is_empty() && mr2.is_empty()) ||
90            (start() == mr2.start() && end() == mr2.end()));
91  }
92
93  size_t byte_size() const { return _word_size * sizeof(HeapWord); }
94  size_t word_size() const { return _word_size; }
95
96  bool is_empty() const { return word_size() == 0; }
97  void* operator new(size_t size) throw();
98  void* operator new [](size_t size) throw();
99  void  operator delete(void* p);
100  void  operator delete [](void* p);
101};
102
103// For iteration over MemRegion's.
104
105class MemRegionClosure : public StackObj {
106public:
107  virtual void do_MemRegion(MemRegion mr) = 0;
108};
109
110// A ResourceObj version of MemRegionClosure
111
112class MemRegionClosureRO: public MemRegionClosure {
113public:
114  void* operator new(size_t size, ResourceObj::allocation_type type, MEMFLAGS flags) throw() {
115        return ResourceObj::operator new(size, type, flags);
116  }
117  void* operator new(size_t size, Arena *arena) throw() {
118        return ResourceObj::operator new(size, arena);
119  }
120  void* operator new(size_t size) throw() {
121        return ResourceObj::operator new(size);
122  }
123
124  void  operator delete(void* p) {} // nothing to do
125};
126
127#endif // SHARE_VM_MEMORY_MEMREGION_HPP
128