1 /*
2 * Copyright (c) 2010, 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 // Forward declarations
26 class CompactibleFreeListSpace;
27
28 class PromotedObject VALUE_OBJ_CLASS_SPEC {
29 private:
30 enum {
31 promoted_mask = right_n_bits(2), // i.e. 0x3
32 displaced_mark = nth_bit(2), // i.e. 0x4
33 next_mask = ~(right_n_bits(3)) // i.e. ~(0x7)
34 };
35
36 // Below, we want _narrow_next in the "higher" 32 bit slot,
37 // whose position will depend on endian-ness of the platform.
38 // This is so that there is no interference with the
39 // cms_free_bit occupying bit position 7 (lsb == 0)
40 // when we are using compressed oops; see FreeChunk::isFree().
41 // We cannot move the cms_free_bit down because currently
42 // biased locking code assumes that age bits are contiguous
43 // with the lock bits. Even if that assumption were relaxed,
44 // the least position we could move this bit to would be
45 // to bit position 3, which would require 16 byte alignment.
46 typedef struct {
47 #ifdef VM_LITTLE_ENDIAN
48 LP64_ONLY(narrowOop _pad;)
49 narrowOop _narrow_next;
50 #else
51 narrowOop _narrow_next;
52 LP64_ONLY(narrowOop _pad;)
53 #endif
54 } Data;
55
56 union {
57 intptr_t _next;
58 Data _data;
59 };
60 public:
61 inline PromotedObject* next() const {
62 assert(!((FreeChunk*)this)->isFree(), "Error");
63 PromotedObject* res;
64 if (UseCompressedOops) {
65 // The next pointer is a compressed oop stored in the top 32 bits
66 res = (PromotedObject*)oopDesc::decode_heap_oop(_data._narrow_next);
67 } else {
68 res = (PromotedObject*)(_next & next_mask);
69 }
70 assert(oop(res)->is_oop_or_null(true /* ignore mark word */), "Not an oop?");
71 return res;
72 }
73 inline void setNext(PromotedObject* x) {
74 assert(((intptr_t)x & ~next_mask) == 0, "Conflict in bit usage, "
75 "or insufficient alignment of objects");
76 if (UseCompressedOops) {
77 assert(_data._narrow_next == 0, "Overwrite?");
78 _data._narrow_next = oopDesc::encode_heap_oop(oop(x));
79 } else {
80 _next |= (intptr_t)x;
81 }
82 assert(!((FreeChunk*)this)->isFree(), "Error");
83 }
84 inline void setPromotedMark() {
85 _next |= promoted_mask;
86 assert(!((FreeChunk*)this)->isFree(), "Error");
87 }
88 inline bool hasPromotedMark() const {
89 assert(!((FreeChunk*)this)->isFree(), "Error");
90 return (_next & promoted_mask) == promoted_mask;
91 }
92 inline void setDisplacedMark() {
93 _next |= displaced_mark;
94 assert(!((FreeChunk*)this)->isFree(), "Error");
95 }
96 inline bool hasDisplacedMark() const {
97 assert(!((FreeChunk*)this)->isFree(), "Error");
98 return (_next & displaced_mark) != 0;
99 }
100 inline void clearNext() {
101 _next = 0;
102 assert(!((FreeChunk*)this)->isFree(), "Error");
103 }
104 debug_only(void *next_addr() { return (void *) &_next; })
105 };
106
107 class SpoolBlock: public FreeChunk {
108 friend class PromotionInfo;
109 protected:
110 SpoolBlock* nextSpoolBlock;
111 size_t bufferSize; // number of usable words in this block
112 markOop* displacedHdr; // the displaced headers start here
113
114 // Note about bufferSize: it denotes the number of entries available plus 1;
115 // legal indices range from 1 through BufferSize - 1. See the verification
116 // code verify() that counts the number of displaced headers spooled.
117 size_t computeBufferSize() {
118 return (size() * sizeof(HeapWord) - sizeof(*this)) / sizeof(markOop);
119 }
120
121 public:
122 void init() {
123 bufferSize = computeBufferSize();
124 displacedHdr = (markOop*)&displacedHdr;
125 nextSpoolBlock = NULL;
126 }
127
128 void print_on(outputStream* st) const;
129 void print() const { print_on(gclog_or_tty); }
130 };
131
132 class PromotionInfo VALUE_OBJ_CLASS_SPEC {
133 bool _tracking; // set if tracking
134 CompactibleFreeListSpace* _space; // the space to which this belongs
135 PromotedObject* _promoHead; // head of list of promoted objects
136 PromotedObject* _promoTail; // tail of list of promoted objects
137 SpoolBlock* _spoolHead; // first spooling block
138 SpoolBlock* _spoolTail; // last non-full spooling block or null
139 SpoolBlock* _splice_point; // when _spoolTail is null, holds list tail
140 SpoolBlock* _spareSpool; // free spool buffer
141 size_t _firstIndex; // first active index in
142 // first spooling block (_spoolHead)
143 size_t _nextIndex; // last active index + 1 in last
144 // spooling block (_spoolTail)
145 private:
146 // ensure that spooling space exists; return true if there is spooling space
147 bool ensure_spooling_space_work();
148
149 public:
150 PromotionInfo() :
151 _tracking(0), _space(NULL),
152 _promoHead(NULL), _promoTail(NULL),
153 _spoolHead(NULL), _spoolTail(NULL),
154 _spareSpool(NULL), _firstIndex(1),
155 _nextIndex(1) {}
156
157 bool noPromotions() const {
158 assert(_promoHead != NULL || _promoTail == NULL, "list inconsistency");
159 return _promoHead == NULL;
160 }
161 void startTrackingPromotions();
162 void stopTrackingPromotions(uint worker_id = 0);
163 bool tracking() const { return _tracking; }
164 void track(PromotedObject* trackOop); // keep track of a promoted oop
165 // The following variant must be used when trackOop is not fully
166 // initialized and has a NULL klass:
167 void track(PromotedObject* trackOop, klassOop klassOfOop); // keep track of a promoted oop
168 void setSpace(CompactibleFreeListSpace* sp) { _space = sp; }
169 CompactibleFreeListSpace* space() const { return _space; }
170 markOop nextDisplacedHeader(); // get next header & forward spool pointer
171 void saveDisplacedHeader(markOop hdr);
172 // save header and forward spool
173
174 inline size_t refillSize() const;
175
176 SpoolBlock* getSpoolBlock(); // return a free spooling block
177 inline bool has_spooling_space() {
178 return _spoolTail != NULL && _spoolTail->bufferSize > _nextIndex;
179 }
180 // ensure that spooling space exists
181 bool ensure_spooling_space() {
182 return has_spooling_space() || ensure_spooling_space_work();
183 }
184 #define PROMOTED_OOPS_ITERATE_DECL(OopClosureType, nv_suffix) \
185 void promoted_oops_iterate##nv_suffix(OopClosureType* cl);
186 ALL_SINCE_SAVE_MARKS_CLOSURES(PROMOTED_OOPS_ITERATE_DECL)
187 #undef PROMOTED_OOPS_ITERATE_DECL
188 void promoted_oops_iterate(OopsInGenClosure* cl) {
189 promoted_oops_iterate_v(cl);
190 }
191 void verify() const;
192 void reset() {
193 _promoHead = NULL;
194 _promoTail = NULL;
195 _spoolHead = NULL;
196 _spoolTail = NULL;
197 _spareSpool = NULL;
198 _firstIndex = 0;
199 _nextIndex = 0;
200
201 }
202
203 void print_on(outputStream* st) const;
204 void print_statistics(uint worker_id) const;
205 };
206