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.
22 *
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 #include "memory/allocation.hpp"
30
31 // Forward declarations
32 class CompactibleFreeListSpace;
33
34 class PromotedObject VALUE_OBJ_CLASS_SPEC {
35 private:
36 enum {
37 promoted_mask = right_n_bits(2), // i.e. 0x3
38 displaced_mark = nth_bit(2), // i.e. 0x4
39 next_mask = ~(right_n_bits(3)) // i.e. ~(0x7)
40 };
41
42 // Below, we want _narrow_next in the "higher" 32 bit slot,
43 // whose position will depend on endian-ness of the platform.
44 // This is so that there is no interference with the
45 // cms_free_bit occupying bit position 7 (lsb == 0)
46 // when we are using compressed oops; see FreeChunk::is_free().
47 // We cannot move the cms_free_bit down because currently
48 // biased locking code assumes that age bits are contiguous
49 // with the lock bits. Even if that assumption were relaxed,
50 // the least position we could move this bit to would be
51 // to bit position 3, which would require 16 byte alignment.
52 typedef struct {
53 #ifdef VM_LITTLE_ENDIAN
54 LP64_ONLY(narrowOop _pad;)
55 narrowOop _narrow_next;
56 #else
57 narrowOop _narrow_next;
58 LP64_ONLY(narrowOop _pad;)
59 #endif
60 } Data;
61
62 union {
63 intptr_t _next;
64 Data _data;
65 };
66 public:
67 PromotedObject* next() const;
68 void setNext(PromotedObject* x);
69 inline void setPromotedMark() {
70 _next |= promoted_mask;
71 assert(!((FreeChunk*)this)->is_free(), "Error");
72 }
73 inline bool hasPromotedMark() const {
74 assert(!((FreeChunk*)this)->is_free(), "Error");
75 return (_next & promoted_mask) == promoted_mask;
76 }
77 inline void setDisplacedMark() {
78 _next |= displaced_mark;
79 assert(!((FreeChunk*)this)->is_free(), "Error");
80 }
81 inline bool hasDisplacedMark() const {
82 assert(!((FreeChunk*)this)->is_free(), "Error");
83 return (_next & displaced_mark) != 0;
84 }
85 inline void clear_next() {
86 _next = 0;
87 assert(!((FreeChunk*)this)->is_free(), "Error");
88 }
89 debug_only(void *next_addr() { return (void *) &_next; })
90 };
91
92 class SpoolBlock: public FreeChunk {
93 friend class PromotionInfo;
94 protected:
95 SpoolBlock* nextSpoolBlock;
96 size_t bufferSize; // number of usable words in this block
97 markOop* displacedHdr; // the displaced headers start here
98
99 // Note about bufferSize: it denotes the number of entries available plus 1;
100 // legal indices range from 1 through BufferSize - 1. See the verification
101 // code verify() that counts the number of displaced headers spooled.
102 size_t computeBufferSize() {
103 return (size() * sizeof(HeapWord) - sizeof(*this)) / sizeof(markOop);
104 }
105
106 public:
107 void init() {
108 bufferSize = computeBufferSize();
109 displacedHdr = (markOop*)&displacedHdr;
110 nextSpoolBlock = NULL;
111 }
112
113 void print_on(outputStream* st) const;
114 void print() const { print_on(tty); }
115 };
116
117 class PromotionInfo VALUE_OBJ_CLASS_SPEC {
118 bool _tracking; // set if tracking
119 CompactibleFreeListSpace* _space; // the space to which this belongs
120 PromotedObject* _promoHead; // head of list of promoted objects
121 PromotedObject* _promoTail; // tail of list of promoted objects
122 SpoolBlock* _spoolHead; // first spooling block
123 SpoolBlock* _spoolTail; // last non-full spooling block or null
124 SpoolBlock* _splice_point; // when _spoolTail is null, holds list tail
125 SpoolBlock* _spareSpool; // free spool buffer
126 size_t _firstIndex; // first active index in
127 // first spooling block (_spoolHead)
128 size_t _nextIndex; // last active index + 1 in last
129 // spooling block (_spoolTail)
130 private:
131 // ensure that spooling space exists; return true if there is spooling space
132 bool ensure_spooling_space_work();
133
134 public:
135 PromotionInfo() :
136 _tracking(0), _space(NULL),
137 _promoHead(NULL), _promoTail(NULL),
138 _spoolHead(NULL), _spoolTail(NULL),
139 _spareSpool(NULL), _firstIndex(1),
140 _nextIndex(1) {}
141
142 bool noPromotions() const {
143 assert(_promoHead != NULL || _promoTail == NULL, "list inconsistency");
144 return _promoHead == NULL;
145 }
146 void startTrackingPromotions();
147 void stopTrackingPromotions();
148 bool tracking() const { return _tracking; }
149 void track(PromotedObject* trackOop); // keep track of a promoted oop
150 // The following variant must be used when trackOop is not fully
151 // initialized and has a NULL klass:
152 void track(PromotedObject* trackOop, Klass* klassOfOop); // keep track of a promoted oop
153 void setSpace(CompactibleFreeListSpace* sp) { _space = sp; }
154 CompactibleFreeListSpace* space() const { return _space; }
155 markOop nextDisplacedHeader(); // get next header & forward spool pointer
156 void saveDisplacedHeader(markOop hdr);
157 // save header and forward spool
158
159 inline size_t refillSize() const;
160
161 SpoolBlock* getSpoolBlock(); // return a free spooling block
162 inline bool has_spooling_space() {
163 return _spoolTail != NULL && _spoolTail->bufferSize > _nextIndex;
164 }
165 // ensure that spooling space exists
166 bool ensure_spooling_space() {
167 return has_spooling_space() || ensure_spooling_space_work();
168 }
169 #define PROMOTED_OOPS_ITERATE_DECL(OopClosureType, nv_suffix) \
170 void promoted_oops_iterate##nv_suffix(OopClosureType* cl);
171 ALL_SINCE_SAVE_MARKS_CLOSURES(PROMOTED_OOPS_ITERATE_DECL)
172 #undef PROMOTED_OOPS_ITERATE_DECL
173 void promoted_oops_iterate(OopsInGenClosure* cl) {
174 promoted_oops_iterate_v(cl);
175 }
176 void verify() const;
177 void reset() {
178 _promoHead = NULL;
179 _promoTail = NULL;
180 _spoolHead = NULL;
181 _spoolTail = NULL;
182 _spareSpool = NULL;
183 _firstIndex = 0;
184 _nextIndex = 0;
185
186 }
187
188 void print_on(outputStream* st) const;
189 };
190
191
192 #endif // SHARE_VM_GC_CMS_PROMOTIONINFO_HPP