1 /*
2 * Copyright (c) 2010, 2016, 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_CMS_PROMOTIONINFO_HPP
26 #define SHARE_VM_GC_CMS_PROMOTIONINFO_HPP
27
28 #include "gc/cms/freeChunk.hpp"
29
30 // Forward declarations
31 class CompactibleFreeListSpace;
32
33 class PromotedObject {
34 private:
35 enum {
36 promoted_mask = right_n_bits(2), // i.e. 0x3
37 displaced_mark = nth_bit(2), // i.e. 0x4
38 next_mask = ~(right_n_bits(3)) // i.e. ~(0x7)
39 };
40
41 // Below, we want _narrow_next in the "higher" 32 bit slot,
42 // whose position will depend on endian-ness of the platform.
43 // This is so that there is no interference with the
44 // cms_free_bit occupying bit position 7 (lsb == 0)
45 // when we are using compressed oops; see FreeChunk::is_free().
46 // We cannot move the cms_free_bit down because currently
47 // biased locking code assumes that age bits are contiguous
48 // with the lock bits. Even if that assumption were relaxed,
49 // the least position we could move this bit to would be
50 // to bit position 3, which would require 16 byte alignment.
51 typedef struct {
52 #ifdef VM_LITTLE_ENDIAN
53 LP64_ONLY(narrowOop _pad;)
54 narrowOop _narrow_next;
55 #else
56 narrowOop _narrow_next;
57 LP64_ONLY(narrowOop _pad;)
58 #endif
59 } Data;
60
61 union {
62 intptr_t _next;
63 Data _data;
64 };
65 public:
66 PromotedObject* next() const;
67 void setNext(PromotedObject* x);
68 inline void setPromotedMark() {
69 _next |= promoted_mask;
70 assert(!((FreeChunk*)this)->is_free(), "Error");
71 }
72 inline bool hasPromotedMark() const {
73 assert(!((FreeChunk*)this)->is_free(), "Error");
74 return (_next & promoted_mask) == promoted_mask;
75 }
76 inline void setDisplacedMark() {
77 _next |= displaced_mark;
78 assert(!((FreeChunk*)this)->is_free(), "Error");
79 }
80 inline bool hasDisplacedMark() const {
81 assert(!((FreeChunk*)this)->is_free(), "Error");
82 return (_next & displaced_mark) != 0;
83 }
84 inline void clear_next() {
85 _next = 0;
86 assert(!((FreeChunk*)this)->is_free(), "Error");
87 }
88 debug_only(void *next_addr() { return (void *) &_next; })
89 };
90
91 class SpoolBlock: public FreeChunk {
92 friend class PromotionInfo;
93 protected:
94 SpoolBlock* nextSpoolBlock;
95 size_t bufferSize; // number of usable words in this block
96 markOop* displacedHdr; // the displaced headers start here
97
98 // Note about bufferSize: it denotes the number of entries available plus 1;
99 // legal indices range from 1 through BufferSize - 1. See the verification
100 // code verify() that counts the number of displaced headers spooled.
101 size_t computeBufferSize() {
102 return (size() * sizeof(HeapWord) - sizeof(*this)) / sizeof(markOop);
103 }
104
105 public:
106 void init() {
107 bufferSize = computeBufferSize();
108 displacedHdr = (markOop*)&displacedHdr;
109 nextSpoolBlock = NULL;
110 }
111
112 void print_on(outputStream* st) const;
113 void print() const { print_on(tty); }
114 };
115
116 class PromotionInfo {
117 bool _tracking; // set if tracking
118 CompactibleFreeListSpace* _space; // the space to which this belongs
119 PromotedObject* _promoHead; // head of list of promoted objects
120 PromotedObject* _promoTail; // tail of list of promoted objects
121 SpoolBlock* _spoolHead; // first spooling block
122 SpoolBlock* _spoolTail; // last non-full spooling block or null
123 SpoolBlock* _splice_point; // when _spoolTail is null, holds list tail
124 SpoolBlock* _spareSpool; // free spool buffer
125 size_t _firstIndex; // first active index in
126 // first spooling block (_spoolHead)
127 size_t _nextIndex; // last active index + 1 in last
128 // spooling block (_spoolTail)
129 private:
130 // ensure that spooling space exists; return true if there is spooling space
131 bool ensure_spooling_space_work();
132
133 public:
134 PromotionInfo() :
135 _tracking(0), _space(NULL),
136 _promoHead(NULL), _promoTail(NULL),
137 _spoolHead(NULL), _spoolTail(NULL),
138 _spareSpool(NULL), _firstIndex(1),
139 _nextIndex(1) {}
140
141 bool noPromotions() const {
142 assert(_promoHead != NULL || _promoTail == NULL, "list inconsistency");
143 return _promoHead == NULL;
144 }
145 void startTrackingPromotions();
146 void stopTrackingPromotions();
147 bool tracking() const { return _tracking; }
148 void track(PromotedObject* trackOop); // keep track of a promoted oop
149 // The following variant must be used when trackOop is not fully
150 // initialized and has a NULL klass:
151 void track(PromotedObject* trackOop, Klass* klassOfOop); // keep track of a promoted oop
152 void setSpace(CompactibleFreeListSpace* sp) { _space = sp; }
153 CompactibleFreeListSpace* space() const { return _space; }
154 markOop nextDisplacedHeader(); // get next header & forward spool pointer
155 void saveDisplacedHeader(markOop hdr);
156 // save header and forward spool
157
158 inline size_t refillSize() const;
159
160 SpoolBlock* getSpoolBlock(); // return a free spooling block
161 inline bool has_spooling_space() {
162 return _spoolTail != NULL && _spoolTail->bufferSize > _nextIndex;
163 }
164 // ensure that spooling space exists
165 bool ensure_spooling_space() {
166 return has_spooling_space() || ensure_spooling_space_work();
167 }
168 #define PROMOTED_OOPS_ITERATE_DECL(OopClosureType, nv_suffix) \
169 void promoted_oops_iterate##nv_suffix(OopClosureType* cl);
170 ALL_SINCE_SAVE_MARKS_CLOSURES(PROMOTED_OOPS_ITERATE_DECL)
171 #undef PROMOTED_OOPS_ITERATE_DECL
172 void promoted_oops_iterate(OopsInGenClosure* cl) {
173 promoted_oops_iterate_v(cl);
174 }
175 void verify() const;
176 void reset() {
177 _promoHead = NULL;
178 _promoTail = NULL;
179 _spoolHead = NULL;
180 _spoolTail = NULL;
181 _spareSpool = NULL;
182 _firstIndex = 0;
183 _nextIndex = 0;
184
185 }
186
187 void print_on(outputStream* st) const;
188 };
189
190
191 #endif // SHARE_VM_GC_CMS_PROMOTIONINFO_HPP