Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/parallelScavenge/objectStartArray.hpp @ 1562:dfe27f03244a
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author | trims |
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date | Tue, 01 Jun 2010 11:48:33 -0700 |
parents | c18cbe5936b8 |
children | f95d63e2154a |
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0 | 1 /* |
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2 * Copyright (c) 2001, 2005, 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
c18cbe5936b8
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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 | |
25 // | |
26 // This class can be used to locate the beginning of an object in the | |
27 // covered region. | |
28 // | |
29 | |
30 class ObjectStartArray : public CHeapObj { | |
31 friend class VerifyObjectStartArrayClosure; | |
32 | |
33 private: | |
34 PSVirtualSpace _virtual_space; | |
35 MemRegion _reserved_region; | |
36 MemRegion _covered_region; | |
37 MemRegion _blocks_region; | |
38 jbyte* _raw_base; | |
39 jbyte* _offset_base; | |
40 | |
41 public: | |
42 | |
43 enum BlockValueConstants { | |
44 clean_block = -1 | |
45 }; | |
46 | |
47 enum BlockSizeConstants { | |
48 block_shift = 9, | |
49 block_size = 1 << block_shift, | |
50 block_size_in_words = block_size / sizeof(HeapWord) | |
51 }; | |
52 | |
53 protected: | |
54 | |
55 // Mapping from address to object start array entry | |
56 jbyte* block_for_addr(void* p) const { | |
57 assert(_covered_region.contains(p), | |
58 "out of bounds access to object start array"); | |
59 jbyte* result = &_offset_base[uintptr_t(p) >> block_shift]; | |
60 assert(_blocks_region.contains(result), | |
61 "out of bounds result in byte_for"); | |
62 return result; | |
63 } | |
64 | |
65 // Mapping from object start array entry to address of first word | |
66 HeapWord* addr_for_block(jbyte* p) { | |
67 assert(_blocks_region.contains(p), | |
68 "out of bounds access to object start array"); | |
69 size_t delta = pointer_delta(p, _offset_base, sizeof(jbyte)); | |
70 HeapWord* result = (HeapWord*) (delta << block_shift); | |
71 assert(_covered_region.contains(result), | |
72 "out of bounds accessor from card marking array"); | |
73 return result; | |
74 } | |
75 | |
76 // Mapping that includes the derived offset. | |
77 // If the block is clean, returns the last address in the covered region. | |
78 // If the block is < index 0, returns the start of the covered region. | |
79 HeapWord* offset_addr_for_block (jbyte* p) const { | |
80 // We have to do this before the assert | |
81 if (p < _raw_base) { | |
82 return _covered_region.start(); | |
83 } | |
84 | |
85 assert(_blocks_region.contains(p), | |
86 "out of bounds access to object start array"); | |
87 | |
88 if (*p == clean_block) { | |
89 return _covered_region.end(); | |
90 } | |
91 | |
92 size_t delta = pointer_delta(p, _offset_base, sizeof(jbyte)); | |
93 HeapWord* result = (HeapWord*) (delta << block_shift); | |
94 result += *p; | |
95 | |
96 assert(_covered_region.contains(result), | |
97 "out of bounds accessor from card marking array"); | |
98 | |
99 return result; | |
100 } | |
101 | |
102 public: | |
103 | |
104 // This method is in lieu of a constructor, so that this class can be | |
105 // embedded inline in other classes. | |
106 void initialize(MemRegion reserved_region); | |
107 | |
108 void set_covered_region(MemRegion mr); | |
109 | |
110 void reset(); | |
111 | |
112 MemRegion covered_region() { return _covered_region; } | |
113 | |
114 void allocate_block(HeapWord* p) { | |
115 assert(_covered_region.contains(p), "Must be in covered region"); | |
116 jbyte* block = block_for_addr(p); | |
117 HeapWord* block_base = addr_for_block(block); | |
118 size_t offset = pointer_delta(p, block_base, sizeof(HeapWord*)); | |
119 assert(offset < 128, "Sanity"); | |
120 // When doing MT offsets, we can't assert this. | |
121 //assert(offset > *block, "Found backwards allocation"); | |
122 *block = (jbyte)offset; | |
123 | |
124 // tty->print_cr("[%p]", p); | |
125 } | |
126 | |
127 // Optimized for finding the first object that crosses into | |
128 // a given block. The blocks contain the offset of the last | |
129 // object in that block. Scroll backwards by one, and the first | |
605 | 130 // object hit should be at the beginning of the block |
0 | 131 HeapWord* object_start(HeapWord* addr) const { |
132 assert(_covered_region.contains(addr), "Must be in covered region"); | |
133 jbyte* block = block_for_addr(addr); | |
134 HeapWord* scroll_forward = offset_addr_for_block(block--); | |
135 while (scroll_forward > addr) { | |
136 scroll_forward = offset_addr_for_block(block--); | |
137 } | |
138 | |
139 HeapWord* next = scroll_forward; | |
140 while (next <= addr) { | |
141 scroll_forward = next; | |
142 next += oop(next)->size(); | |
143 } | |
144 assert(scroll_forward <= addr, "wrong order for current and arg"); | |
145 assert(addr <= next, "wrong order for arg and next"); | |
146 return scroll_forward; | |
147 } | |
148 | |
149 bool is_block_allocated(HeapWord* addr) { | |
150 assert(_covered_region.contains(addr), "Must be in covered region"); | |
151 jbyte* block = block_for_addr(addr); | |
152 if (*block == clean_block) | |
153 return false; | |
154 | |
155 return true; | |
156 } | |
157 | |
158 // Return true if an object starts in the range of heap addresses. | |
159 // If an object starts at an address corresponding to | |
160 // "start", the method will return true. | |
161 bool object_starts_in_range(HeapWord* start_addr, HeapWord* end_addr) const; | |
162 }; |