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annotate src/share/vm/gc_implementation/parallelScavenge/objectStartArray.hpp @ 3687:7958ebb561b0
Merge
author | Lukas Stadler <lukas.stadler@jku.at> |
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date | Fri, 18 Nov 2011 17:20:38 +0100 |
parents | f95d63e2154a |
children | d2a62e0f25eb |
rev | line source |
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0 | 1 /* |
1972 | 2 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved. |
0 | 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 * | |
1552
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #ifndef SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_OBJECTSTARTARRAY_HPP |
26 #define SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_OBJECTSTARTARRAY_HPP | |
27 | |
28 #include "gc_implementation/parallelScavenge/psVirtualspace.hpp" | |
29 #include "memory/allocation.hpp" | |
30 #include "memory/memRegion.hpp" | |
31 #include "oops/oop.hpp" | |
32 | |
0 | 33 // |
34 // This class can be used to locate the beginning of an object in the | |
35 // covered region. | |
36 // | |
37 | |
38 class ObjectStartArray : public CHeapObj { | |
39 friend class VerifyObjectStartArrayClosure; | |
40 | |
41 private: | |
42 PSVirtualSpace _virtual_space; | |
43 MemRegion _reserved_region; | |
44 MemRegion _covered_region; | |
45 MemRegion _blocks_region; | |
46 jbyte* _raw_base; | |
47 jbyte* _offset_base; | |
48 | |
49 public: | |
50 | |
51 enum BlockValueConstants { | |
52 clean_block = -1 | |
53 }; | |
54 | |
55 enum BlockSizeConstants { | |
56 block_shift = 9, | |
57 block_size = 1 << block_shift, | |
58 block_size_in_words = block_size / sizeof(HeapWord) | |
59 }; | |
60 | |
61 protected: | |
62 | |
63 // Mapping from address to object start array entry | |
64 jbyte* block_for_addr(void* p) const { | |
65 assert(_covered_region.contains(p), | |
66 "out of bounds access to object start array"); | |
67 jbyte* result = &_offset_base[uintptr_t(p) >> block_shift]; | |
68 assert(_blocks_region.contains(result), | |
69 "out of bounds result in byte_for"); | |
70 return result; | |
71 } | |
72 | |
73 // Mapping from object start array entry to address of first word | |
74 HeapWord* addr_for_block(jbyte* p) { | |
75 assert(_blocks_region.contains(p), | |
76 "out of bounds access to object start array"); | |
77 size_t delta = pointer_delta(p, _offset_base, sizeof(jbyte)); | |
78 HeapWord* result = (HeapWord*) (delta << block_shift); | |
79 assert(_covered_region.contains(result), | |
80 "out of bounds accessor from card marking array"); | |
81 return result; | |
82 } | |
83 | |
84 // Mapping that includes the derived offset. | |
85 // If the block is clean, returns the last address in the covered region. | |
86 // If the block is < index 0, returns the start of the covered region. | |
87 HeapWord* offset_addr_for_block (jbyte* p) const { | |
88 // We have to do this before the assert | |
89 if (p < _raw_base) { | |
90 return _covered_region.start(); | |
91 } | |
92 | |
93 assert(_blocks_region.contains(p), | |
94 "out of bounds access to object start array"); | |
95 | |
96 if (*p == clean_block) { | |
97 return _covered_region.end(); | |
98 } | |
99 | |
100 size_t delta = pointer_delta(p, _offset_base, sizeof(jbyte)); | |
101 HeapWord* result = (HeapWord*) (delta << block_shift); | |
102 result += *p; | |
103 | |
104 assert(_covered_region.contains(result), | |
105 "out of bounds accessor from card marking array"); | |
106 | |
107 return result; | |
108 } | |
109 | |
110 public: | |
111 | |
112 // This method is in lieu of a constructor, so that this class can be | |
113 // embedded inline in other classes. | |
114 void initialize(MemRegion reserved_region); | |
115 | |
116 void set_covered_region(MemRegion mr); | |
117 | |
118 void reset(); | |
119 | |
120 MemRegion covered_region() { return _covered_region; } | |
121 | |
122 void allocate_block(HeapWord* p) { | |
123 assert(_covered_region.contains(p), "Must be in covered region"); | |
124 jbyte* block = block_for_addr(p); | |
125 HeapWord* block_base = addr_for_block(block); | |
126 size_t offset = pointer_delta(p, block_base, sizeof(HeapWord*)); | |
127 assert(offset < 128, "Sanity"); | |
128 // When doing MT offsets, we can't assert this. | |
129 //assert(offset > *block, "Found backwards allocation"); | |
130 *block = (jbyte)offset; | |
131 | |
132 // tty->print_cr("[%p]", p); | |
133 } | |
134 | |
135 // Optimized for finding the first object that crosses into | |
136 // a given block. The blocks contain the offset of the last | |
137 // object in that block. Scroll backwards by one, and the first | |
605 | 138 // object hit should be at the beginning of the block |
0 | 139 HeapWord* object_start(HeapWord* addr) const { |
140 assert(_covered_region.contains(addr), "Must be in covered region"); | |
141 jbyte* block = block_for_addr(addr); | |
142 HeapWord* scroll_forward = offset_addr_for_block(block--); | |
143 while (scroll_forward > addr) { | |
144 scroll_forward = offset_addr_for_block(block--); | |
145 } | |
146 | |
147 HeapWord* next = scroll_forward; | |
148 while (next <= addr) { | |
149 scroll_forward = next; | |
150 next += oop(next)->size(); | |
151 } | |
152 assert(scroll_forward <= addr, "wrong order for current and arg"); | |
153 assert(addr <= next, "wrong order for arg and next"); | |
154 return scroll_forward; | |
155 } | |
156 | |
157 bool is_block_allocated(HeapWord* addr) { | |
158 assert(_covered_region.contains(addr), "Must be in covered region"); | |
159 jbyte* block = block_for_addr(addr); | |
160 if (*block == clean_block) | |
161 return false; | |
162 | |
163 return true; | |
164 } | |
165 | |
166 // Return true if an object starts in the range of heap addresses. | |
167 // If an object starts at an address corresponding to | |
168 // "start", the method will return true. | |
169 bool object_starts_in_range(HeapWord* start_addr, HeapWord* end_addr) const; | |
170 }; | |
1972 | 171 |
172 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_OBJECTSTARTARRAY_HPP |