heap/CopiedBlock.h

   1 /*
   2  * Copyright (C) 2011 Apple Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #ifndef CopiedBlock_h
  27 #define CopiedBlock_h
  28
  29 #include "BlockAllocator.h"
  30 #include "CopyWorkList.h"
  31 #include "HeapBlock.h"
  32 #include "JSCJSValue.h"
  33 #include "Options.h"
  34 #include <wtf/Atomics.h>
  35 #include <wtf/OwnPtr.h>
  36 #include <wtf/PassOwnPtr.h>
  37
  38 namespace JSC {
  39
  40 class CopiedSpace;
  41
  42 class CopiedBlock : public HeapBlock<CopiedBlock> {
  43     friend class CopiedSpace;
  44     friend class CopiedAllocator;
  45 public:
  46     static CopiedBlock* create(DeadBlock*);
  47     static CopiedBlock* createNoZeroFill(DeadBlock*);
  48
  49     void pin();
  50     bool isPinned();
  51
  52     bool isOversize();
  53
  54     unsigned liveBytes();
  55     void reportLiveBytes(JSCell*, unsigned);
  56     void didSurviveGC();
  57     void didEvacuateBytes(unsigned);
  58     bool shouldEvacuate();
  59     bool canBeRecycled();
  60
  61     // The payload is the region of the block that is usable for allocations.
  62     char* payload();
  63     char* payloadEnd();
  64     size_t payloadCapacity();
  65
  66     // The data is the region of the block that has been used for allocations.
  67     char* data();
  68     char* dataEnd();
  69     size_t dataSize();
  70
  71     // The wilderness is the region of the block that is usable for allocations
  72     // but has not been so used.
  73     char* wilderness();
  74     char* wildernessEnd();
  75     size_t wildernessSize();
  76
  77     size_t size();
  78     size_t capacity();
  79
  80     static const size_t blockSize = 32 * KB;
  81
  82     bool hasWorkList();
  83     CopyWorkList& workList();
  84
  85 private:
  86     CopiedBlock(Region*);
  87     void zeroFillWilderness(); // Can be called at any time to zero-fill to the end of the block.
  88
  89 #if ENABLE(PARALLEL_GC)
  90     SpinLock m_workListLock;
  91 #endif
  92     OwnPtr<CopyWorkList> m_workList;
  93
  94     size_t m_remaining;
  95     uintptr_t m_isPinned;
  96     unsigned m_liveBytes;
  97 };
  98
  99 inline CopiedBlock* CopiedBlock::createNoZeroFill(DeadBlock* block)
 100 {
 101     Region* region = block->region();
 102     return new(NotNull, block) CopiedBlock(region);
 103 }
 104
 105 inline CopiedBlock* CopiedBlock::create(DeadBlock* block)
 106 {
 107     CopiedBlock* newBlock = createNoZeroFill(block);
 108     newBlock->zeroFillWilderness();
 109     return newBlock;
 110 }
 111
 112 inline void CopiedBlock::zeroFillWilderness()
 113 {
 114 #if USE(JSVALUE64)
 115     memset(wilderness(), 0, wildernessSize());
 116 #else
 117     JSValue emptyValue;
 118     JSValue* limit = reinterpret_cast_ptr<JSValue*>(wildernessEnd());
 119     for (JSValue* currentValue = reinterpret_cast_ptr<JSValue*>(wilderness()); currentValue < limit; currentValue++)
 120         *currentValue = emptyValue;
 121 #endif
 122 }
 123
 124 inline CopiedBlock::CopiedBlock(Region* region)
 125     : HeapBlock<CopiedBlock>(region)
 126     , m_remaining(payloadCapacity())
 127     , m_isPinned(false)
 128     , m_liveBytes(0)
 129 {
 130 #if ENABLE(PARALLEL_GC)
 131     m_workListLock.Init();
 132 #endif
 133     ASSERT(is8ByteAligned(reinterpret_cast<void*>(m_remaining)));
 134 }
 135
 136 inline void CopiedBlock::didSurviveGC()
 137 {
 138     m_liveBytes = 0;
 139     m_isPinned = false;
 140     if (m_workList)
 141         m_workList.clear();
 142 }
 143
 144 inline void CopiedBlock::didEvacuateBytes(unsigned bytes)
 145 {
 146     ASSERT(m_liveBytes >= bytes);
 147     m_liveBytes -= bytes;
 148 }
 149
 150 inline bool CopiedBlock::canBeRecycled()
 151 {
 152     return !m_liveBytes;
 153 }
 154
 155 inline bool CopiedBlock::shouldEvacuate()
 156 {
 157     return static_cast<double>(m_liveBytes) / static_cast<double>(payloadCapacity()) <= Options::minCopiedBlockUtilization();
 158 }
 159
 160 inline void CopiedBlock::pin()
 161 {
 162     m_isPinned = true;
 163     if (m_workList)
 164         m_workList.clear();
 165 }
 166
 167 inline bool CopiedBlock::isPinned()
 168 {
 169     return m_isPinned;
 170 }
 171
 172 inline bool CopiedBlock::isOversize()
 173 {
 174     return region()->isCustomSize();
 175 }
 176
 177 inline unsigned CopiedBlock::liveBytes()
 178 {
 179     return m_liveBytes;
 180 }
 181
 182 inline char* CopiedBlock::payload()
 183 {
 184     return reinterpret_cast<char*>(this) + ((sizeof(CopiedBlock) + 7) & ~7);
 185 }
 186
 187 inline char* CopiedBlock::payloadEnd()
 188 {
 189     return reinterpret_cast<char*>(this) + region()->blockSize();
 190 }
 191
 192 inline size_t CopiedBlock::payloadCapacity()
 193 {
 194     return payloadEnd() - payload();
 195 }
 196
 197 inline char* CopiedBlock::data()
 198 {
 199     return payload();
 200 }
 201
 202 inline char* CopiedBlock::dataEnd()
 203 {
 204     return payloadEnd() - m_remaining;
 205 }
 206
 207 inline size_t CopiedBlock::dataSize()
 208 {
 209     return dataEnd() - data();
 210 }
 211
 212 inline char* CopiedBlock::wilderness()
 213 {
 214     return dataEnd();
 215 }
 216
 217 inline char* CopiedBlock::wildernessEnd()
 218 {
 219     return payloadEnd();
 220 }
 221
 222 inline size_t CopiedBlock::wildernessSize()
 223 {
 224     return wildernessEnd() - wilderness();
 225 }
 226
 227 inline size_t CopiedBlock::size()
 228 {
 229     return dataSize();
 230 }
 231
 232 inline size_t CopiedBlock::capacity()
 233 {
 234     return region()->blockSize();
 235 }
 236
 237 inline bool CopiedBlock::hasWorkList()
 238 {
 239     return !!m_workList;
 240 }
 241
 242 inline CopyWorkList& CopiedBlock::workList()
 243 {
 244     return *m_workList;
 245 }
 246
 247 } // namespace JSC
 248
 249 #endif