Thu, 13 Jun 2013 22:02:40 -0700
8014431: cleanup warnings indicated by the -Wunused-value compiler option on linux
Reviewed-by: dholmes, coleenp
Contributed-by: jeremymanson@google.com, calvin.cheung@oracle.com
1 /*
2 * Copyright (c) 2000, 2012, 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
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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 */
25 #ifndef SHARE_VM_MEMORY_MEMREGION_HPP
26 #define SHARE_VM_MEMORY_MEMREGION_HPP
28 #include "memory/allocation.hpp"
29 #include "utilities/debug.hpp"
30 #include "utilities/globalDefinitions.hpp"
32 // A very simple data structure representing a contigous region
33 // region of address space.
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.
41 class MetaWord;
43 class MemRegion VALUE_OBJ_CLASS_SPEC {
44 friend class VMStructs;
45 private:
46 HeapWord* _start;
47 size_t _word_size;
49 public:
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 }
62 MemRegion(const MemRegion& mr): _start(mr._start), _word_size(mr._word_size) {}
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;
71 HeapWord* start() const { return _start; }
72 HeapWord* end() const { return _start + _word_size; }
73 HeapWord* last() const { return _start + _word_size - 1; }
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 }
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 }
93 size_t byte_size() const { return _word_size * sizeof(HeapWord); }
94 size_t word_size() const { return _word_size; }
96 bool is_empty() const { return word_size() == 0; }
97 void* operator new(size_t size);
98 void* operator new [](size_t size);
99 void operator delete(void* p);
100 void operator delete [](void* p);
101 };
103 // For iteration over MemRegion's.
105 class MemRegionClosure : public StackObj {
106 public:
107 virtual void do_MemRegion(MemRegion mr) = 0;
108 };
110 // A ResourceObj version of MemRegionClosure
112 class MemRegionClosureRO: public MemRegionClosure {
113 public:
114 void* operator new(size_t size, ResourceObj::allocation_type type, MEMFLAGS flags) {
115 return ResourceObj::operator new(size, type, flags);
116 }
117 void* operator new(size_t size, Arena *arena) {
118 return ResourceObj::operator new(size, arena);
119 }
120 void* operator new(size_t size) {
121 return ResourceObj::operator new(size);
122 }
124 void operator delete(void* p) {} // nothing to do
125 };
127 #endif // SHARE_VM_MEMORY_MEMREGION_HPP