comparison src/hotspot/share/gc/shared/markBitMap.hpp @ 52321:31b159f30fb2

8180193: Make marking bitmap code available to other GCs Reviewed-by: shade, stefank
author rkennke
date Wed, 29 Aug 2018 20:15:09 +0200
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children 5b87d3fc1093
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-1:000000000000 0:80f1e2d4b11b
1 /*
2 * Copyright (c) 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_GC_SHARED_MARKBITMAP_HPP
26 #define SHARE_VM_GC_SHARED_MARKBITMAP_HPP
27
28 #include "memory/memRegion.hpp"
29 #include "oops/oopsHierarchy.hpp"
30 #include "utilities/bitMap.hpp"
31
32 // A generic mark bitmap for concurrent marking. This is essentially a wrapper
33 // around the BitMap class that is based on HeapWords, with one bit per (1 << _shifter) HeapWords.
34 class MarkBitMap {
35 protected:
36 MemRegion _covered; // The heap area covered by this bitmap.
37
38 const int _shifter; // Shift amount from heap index to bit index in the bitmap.
39
40 BitMapView _bm; // The actual bitmap.
41
42 virtual void check_mark(HeapWord* addr) NOT_DEBUG_RETURN;
43
44 // Convert from bit offset to address.
45 HeapWord* offset_to_addr(size_t offset) const {
46 return _covered.start() + (offset << _shifter);
47 }
48 // Convert from address to bit offset.
49 size_t addr_to_offset(const HeapWord* addr) const {
50 return pointer_delta(addr, _covered.start()) >> _shifter;
51 }
52 public:
53 static size_t compute_size(size_t heap_size);
54 // Returns the amount of bytes on the heap between two marks in the bitmap.
55 static size_t mark_distance();
56 // Returns how many bytes (or bits) of the heap a single byte (or bit) of the
57 // mark bitmap corresponds to. This is the same as the mark distance above.
58 static size_t heap_map_factor() {
59 return mark_distance();
60 }
61
62 MarkBitMap() : _covered(), _shifter(LogMinObjAlignment), _bm() {}
63
64 // Initializes the underlying BitMap to cover the given area.
65 void initialize(MemRegion heap, MemRegion storage);
66
67 // Read marks
68 bool is_marked(oop obj) const;
69 bool is_marked(HeapWord* addr) const {
70 assert(_covered.contains(addr),
71 "Address " PTR_FORMAT " is outside underlying space from " PTR_FORMAT " to " PTR_FORMAT,
72 p2i(addr), p2i(_covered.start()), p2i(_covered.end()));
73 return _bm.at(addr_to_offset(addr));
74 }
75
76 // Return the address corresponding to the next marked bit at or after
77 // "addr", and before "limit", if "limit" is non-NULL. If there is no
78 // such bit, returns "limit" if that is non-NULL, or else "endWord()".
79 inline HeapWord* get_next_marked_addr(const HeapWord* addr,
80 const HeapWord* limit) const;
81
82 void print_on_error(outputStream* st, const char* prefix) const;
83
84 // Write marks.
85 inline void mark(HeapWord* addr);
86 inline void clear(HeapWord* addr);
87 inline void clear(oop obj);
88 inline bool par_mark(HeapWord* addr);
89 inline bool par_mark(oop obj);
90
91 void clear_range(MemRegion mr);
92 };
93
94 #endif // SHARE_VM_GC_SHARED_MARKBITMAP_HPP