1 /*
2 * Copyright (c) 2015, 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.
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23 */
24
25 #ifndef SHARE_VM_GC_SHARED_CMBITMAP_HPP
26 #define SHARE_VM_GC_SHARED_CMBITMAP_HPP
27
28 #include "memory/memRegion.hpp"
29 #include "oops/oop.inline.hpp"
30 #include "utilities/bitMap.hpp"
31 #include "utilities/globalDefinitions.hpp"
32
33 // A generic CM bit map. This is essentially a wrapper around the BitMap
34 // class, with one bit per (1<<_shifter) HeapWords.
35
36 class CMBitMapRO VALUE_OBJ_CLASS_SPEC {
37 protected:
38 HeapWord* _bmStartWord; // base address of range covered by map
39 size_t _bmWordSize; // map size (in #HeapWords covered)
40 const int _shifter; // map to char or bit
41 BitMap _bm; // the bit map itself
42
43 public:
44 // constructor
45 CMBitMapRO(int shifter);
46
47 enum { do_yield = true };
48
49 // inquiries
50 HeapWord* startWord() const { return _bmStartWord; }
51 size_t sizeInWords() const { return _bmWordSize; }
52 // the following is one past the last word in space
53 HeapWord* endWord() const { return _bmStartWord + _bmWordSize; }
54
55 // read marks
56
57 bool isMarked(HeapWord* addr) const {
58 assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
59 "outside underlying space?");
60 return _bm.at(heapWordToOffset(addr));
61 }
62
63 // iteration
64 inline bool iterate(BitMapClosure* cl, MemRegion mr);
65 inline bool iterate(BitMapClosure* cl);
66
67 // Return the address corresponding to the next marked bit at or after
68 // "addr", and before "limit", if "limit" is non-NULL. If there is no
69 // such bit, returns "limit" if that is non-NULL, or else "endWord()".
70 HeapWord* getNextMarkedWordAddress(const HeapWord* addr,
71 const HeapWord* limit = NULL) const;
72 // Return the address corresponding to the next unmarked bit at or after
73 // "addr", and before "limit", if "limit" is non-NULL. If there is no
74 // such bit, returns "limit" if that is non-NULL, or else "endWord()".
75 HeapWord* getNextUnmarkedWordAddress(const HeapWord* addr,
76 const HeapWord* limit = NULL) const;
77
78 // conversion utilities
79 HeapWord* offsetToHeapWord(size_t offset) const {
80 return _bmStartWord + (offset << _shifter);
81 }
82 size_t heapWordToOffset(const HeapWord* addr) const {
83 return pointer_delta(addr, _bmStartWord) >> _shifter;
84 }
85 int heapWordDiffToOffsetDiff(size_t diff) const;
86
87 // The argument addr should be the start address of a valid object
88 HeapWord* nextObject(HeapWord* addr) {
89 oop obj = (oop) addr;
90 HeapWord* res = addr + obj->size();
91 assert(offsetToHeapWord(heapWordToOffset(res)) == res, "sanity");
92 return res;
93 }
94
95 void print_on_error(outputStream* st, const char* prefix) const;
96
97 // debugging
98 NOT_PRODUCT(bool covers(MemRegion rs) const;)
99 };
100
101 class CMBitMap : public CMBitMapRO {
102
103 public:
104 static size_t compute_size(size_t heap_size);
105 // Returns the amount of bytes on the heap between two marks in the bitmap.
106 static size_t mark_distance();
107 // Returns how many bytes (or bits) of the heap a single byte (or bit) of the
108 // mark bitmap corresponds to. This is the same as the mark distance above. static size_t heap_map_factor() {
109 static size_t heap_map_factor() {
110 return mark_distance();
111 }
112
113 CMBitMap() : CMBitMapRO(LogMinObjAlignment) {}
114
115 // Initializes the underlying BitMap to cover the given area.
116 void initialize(MemRegion heap, MemRegion bitmap);
117
118 // Write marks.
119 inline void mark(HeapWord* addr);
120 inline void clear(HeapWord* addr);
121 inline bool parMark(HeapWord* addr);
122 inline bool parClear(HeapWord* addr);
123
124 void markRange(MemRegion mr);
125 void parMarkRange(MemRegion mr);
126 void clearRange(MemRegion mr);
127
128 // Starting at the bit corresponding to "addr" (inclusive), find the next
129 // "1" bit, if any. This bit starts some run of consecutive "1"'s; find
130 // the end of this run (stopping at "end_addr"). Return the MemRegion
131 // covering from the start of the region corresponding to the first bit
132 // of the run to the end of the region corresponding to the last bit of
133 // the run. If there is no "1" bit at or after "addr", return an empty
134 // MemRegion.
135 MemRegion getAndClearMarkedRegion(HeapWord* addr, HeapWord* end_addr);
136
137 // Clear the whole mark bitmap.
138 virtual void clearAll();
139 };
140
141 #endif // SHARE_VM_GC_SHARED_CMBITMAP_HPP