heap/CopiedAllocator.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 CopiedAllocator_h
  27 #define CopiedAllocator_h
  28
  29 #include "CopiedBlock.h"
  30
  31 namespace JSC {
  32
  33 class CopiedAllocator {
  34     friend class JIT;
  35 public:
  36     CopiedAllocator();
  37     void* allocate(size_t);
  38     bool fitsInCurrentBlock(size_t);
  39     bool wasLastAllocation(void*, size_t);
  40     void startedCopying();
  41     void resetCurrentBlock(CopiedBlock*);
  42     size_t currentCapacity();
  43
  44 private:
  45     CopiedBlock* currentBlock() { return m_currentBlock; }
  46
  47     char* m_currentOffset;
  48     CopiedBlock* m_currentBlock;
  49 };
  50
  51 inline CopiedAllocator::CopiedAllocator()
  52     : m_currentOffset(0)
  53     , m_currentBlock(0)
  54 {
  55 }
  56
  57 inline void* CopiedAllocator::allocate(size_t bytes)
  58 {
  59     ASSERT(m_currentOffset);
  60     ASSERT(is8ByteAligned(reinterpret_cast<void*>(bytes)));
  61     ASSERT(fitsInCurrentBlock(bytes));
  62     void* ptr = static_cast<void*>(m_currentOffset);
  63     m_currentOffset += bytes;
  64     ASSERT(is8ByteAligned(ptr));
  65     return ptr;
  66 }
  67
  68 inline bool CopiedAllocator::fitsInCurrentBlock(size_t bytes)
  69 {
  70     return m_currentOffset + bytes < reinterpret_cast<char*>(m_currentBlock) + HeapBlock::s_blockSize && m_currentOffset + bytes > m_currentOffset;
  71 }
  72
  73 inline bool CopiedAllocator::wasLastAllocation(void* ptr, size_t size)
  74 {
  75     return static_cast<char*>(ptr) + size == m_currentOffset && ptr > m_currentBlock && ptr < reinterpret_cast<char*>(m_currentBlock) + HeapBlock::s_blockSize;
  76 }
  77
  78 inline void CopiedAllocator::startedCopying()
  79 {
  80     if (m_currentBlock)
  81         m_currentBlock->m_offset = static_cast<void*>(m_currentOffset);
  82     m_currentOffset = 0;
  83     m_currentBlock = 0;
  84 }
  85
  86 inline void CopiedAllocator::resetCurrentBlock(CopiedBlock* newBlock)
  87 {
  88     if (m_currentBlock)
  89         m_currentBlock->m_offset = static_cast<void*>(m_currentOffset);
  90     m_currentBlock = newBlock;
  91     m_currentOffset = static_cast<char*>(newBlock->m_offset);
  92 }
  93
  94 inline size_t CopiedAllocator::currentCapacity()
  95 {
  96     return m_currentBlock->capacity();
  97 }
  98
  99 } // namespace JSC
 100
 101 #endif