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(jint _pad;) 55 jint _narrow_next; 56 #else 57 jint _narrow_next; 58 LP64_ONLY(jint _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