1 /* 2 * Copyright (c) 2010, 2015, 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 inline PromotedObject* next() const { 68 assert(!((FreeChunk*)this)->is_free(), "Error"); 69 PromotedObject* res; 70 if (UseCompressedOops) { 71 // The next pointer is a compressed oop stored in the top 32 bits 72 res = (PromotedObject*)oopDesc::decode_heap_oop(_data._narrow_next); 73 } else { 74 res = (PromotedObject*)(_next & next_mask); 75 } 76 assert(oop(res)->is_oop_or_null(true /* ignore mark word */), "Expected an oop or NULL at " PTR_FORMAT, p2i(oop(res))); 77 return res; 78 } 79 inline void setNext(PromotedObject* x) { 80 assert(((intptr_t)x & ~next_mask) == 0, "Conflict in bit usage, " 81 "or insufficient alignment of objects"); 82 if (UseCompressedOops) { 83 assert(_data._narrow_next == 0, "Overwrite?"); 84 _data._narrow_next = oopDesc::encode_heap_oop(oop(x)); 85 } else { 86 _next |= (intptr_t)x; 87 } 88 assert(!((FreeChunk*)this)->is_free(), "Error"); 89 } 90 inline void setPromotedMark() { 91 _next |= promoted_mask; 92 assert(!((FreeChunk*)this)->is_free(), "Error"); 93 } 94 inline bool hasPromotedMark() const { 95 assert(!((FreeChunk*)this)->is_free(), "Error"); 96 return (_next & promoted_mask) == promoted_mask; 97 } 98 inline void setDisplacedMark() { 99 _next |= displaced_mark; 100 assert(!((FreeChunk*)this)->is_free(), "Error"); 101 } 102 inline bool hasDisplacedMark() const { 103 assert(!((FreeChunk*)this)->is_free(), "Error"); 104 return (_next & displaced_mark) != 0; 105 } 106 inline void clear_next() { 107 _next = 0; 108 assert(!((FreeChunk*)this)->is_free(), "Error"); 109 } 110 debug_only(void *next_addr() { return (void *) &_next; }) 111 }; 112 113 class SpoolBlock: public FreeChunk { 114 friend class PromotionInfo; 115 protected: 116 SpoolBlock* nextSpoolBlock; 117 size_t bufferSize; // number of usable words in this block 118 markOop* displacedHdr; // the displaced headers start here 119 120 // Note about bufferSize: it denotes the number of entries available plus 1; 121 // legal indices range from 1 through BufferSize - 1. See the verification 122 // code verify() that counts the number of displaced headers spooled. 123 size_t computeBufferSize() { 124 return (size() * sizeof(HeapWord) - sizeof(*this)) / sizeof(markOop); 125 } 126 127 public: 128 void init() { 129 bufferSize = computeBufferSize(); 130 displacedHdr = (markOop*)&displacedHdr; 131 nextSpoolBlock = NULL; 132 } 133 134 void print_on(outputStream* st) const; 135 void print() const { print_on(gclog_or_tty); } 136 }; 137 138 class PromotionInfo VALUE_OBJ_CLASS_SPEC { 139 bool _tracking; // set if tracking 140 CompactibleFreeListSpace* _space; // the space to which this belongs 141 PromotedObject* _promoHead; // head of list of promoted objects 142 PromotedObject* _promoTail; // tail of list of promoted objects 143 SpoolBlock* _spoolHead; // first spooling block 144 SpoolBlock* _spoolTail; // last non-full spooling block or null 145 SpoolBlock* _splice_point; // when _spoolTail is null, holds list tail 146 SpoolBlock* _spareSpool; // free spool buffer 147 size_t _firstIndex; // first active index in 148 // first spooling block (_spoolHead) 149 size_t _nextIndex; // last active index + 1 in last 150 // spooling block (_spoolTail) 151 private: 152 // ensure that spooling space exists; return true if there is spooling space 153 bool ensure_spooling_space_work(); 154 155 public: 156 PromotionInfo() : 157 _tracking(0), _space(NULL), 158 _promoHead(NULL), _promoTail(NULL), 159 _spoolHead(NULL), _spoolTail(NULL), 160 _spareSpool(NULL), _firstIndex(1), 161 _nextIndex(1) {} 162 163 bool noPromotions() const { 164 assert(_promoHead != NULL || _promoTail == NULL, "list inconsistency"); 165 return _promoHead == NULL; 166 } 167 void startTrackingPromotions(); 168 void stopTrackingPromotions(uint worker_id = 0); 169 bool tracking() const { return _tracking; } 170 void track(PromotedObject* trackOop); // keep track of a promoted oop 171 // The following variant must be used when trackOop is not fully 172 // initialized and has a NULL klass: 173 void track(PromotedObject* trackOop, Klass* klassOfOop); // keep track of a promoted oop 174 void setSpace(CompactibleFreeListSpace* sp) { _space = sp; } 175 CompactibleFreeListSpace* space() const { return _space; } 176 markOop nextDisplacedHeader(); // get next header & forward spool pointer 177 void saveDisplacedHeader(markOop hdr); 178 // save header and forward spool 179 180 inline size_t refillSize() const; 181 182 SpoolBlock* getSpoolBlock(); // return a free spooling block 183 inline bool has_spooling_space() { 184 return _spoolTail != NULL && _spoolTail->bufferSize > _nextIndex; 185 } 186 // ensure that spooling space exists 187 bool ensure_spooling_space() { 188 return has_spooling_space() || ensure_spooling_space_work(); 189 } 190 #define PROMOTED_OOPS_ITERATE_DECL(OopClosureType, nv_suffix) \ 191 void promoted_oops_iterate##nv_suffix(OopClosureType* cl); 192 ALL_SINCE_SAVE_MARKS_CLOSURES(PROMOTED_OOPS_ITERATE_DECL) 193 #undef PROMOTED_OOPS_ITERATE_DECL 194 void promoted_oops_iterate(OopsInGenClosure* cl) { 195 promoted_oops_iterate_v(cl); 196 } 197 void verify() const; 198 void reset() { 199 _promoHead = NULL; 200 _promoTail = NULL; 201 _spoolHead = NULL; 202 _spoolTail = NULL; 203 _spareSpool = NULL; 204 _firstIndex = 0; 205 _nextIndex = 0; 206 207 } 208 209 void print_on(outputStream* st) const; 210 void print_statistics(uint worker_id) const; 211 }; 212 213 214 #endif // SHARE_VM_GC_CMS_PROMOTIONINFO_HPP