heap/ConservativeRoots.cpp

   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. AND ITS CONTRIBUTORS ``AS IS''
  14  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  15  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
  17  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  18  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  19  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  20  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  21  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  22  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  23  * THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #include "config.h"
  27 #include "ConservativeRoots.h"
  28
  29 #include "CopiedSpace.h"
  30 #include "CopiedSpaceInlineMethods.h"
  31 #include "CodeBlock.h"
  32 #include "DFGCodeBlocks.h"
  33 #include "JSCell.h"
  34 #include "JSObject.h"
  35 #include "Structure.h"
  36
  37 namespace JSC {
  38
  39 ConservativeRoots::ConservativeRoots(const MarkedBlockSet* blocks, CopiedSpace* copiedSpace)
  40     : m_roots(m_inlineRoots)
  41     , m_size(0)
  42     , m_capacity(inlineCapacity)
  43     , m_blocks(blocks)
  44     , m_copiedSpace(copiedSpace)
  45 {
  46 }
  47
  48 ConservativeRoots::~ConservativeRoots()
  49 {
  50     if (m_roots != m_inlineRoots)
  51         OSAllocator::decommitAndRelease(m_roots, m_capacity * sizeof(JSCell*));
  52 }
  53
  54 void ConservativeRoots::grow()
  55 {
  56     size_t newCapacity = m_capacity == inlineCapacity ? nonInlineCapacity : m_capacity * 2;
  57     JSCell** newRoots = static_cast<JSCell**>(OSAllocator::reserveAndCommit(newCapacity * sizeof(JSCell*)));
  58     memcpy(newRoots, m_roots, m_size * sizeof(JSCell*));
  59     if (m_roots != m_inlineRoots)
  60         OSAllocator::decommitAndRelease(m_roots, m_capacity * sizeof(JSCell*));
  61     m_capacity = newCapacity;
  62     m_roots = newRoots;
  63 }
  64
  65 class DummyMarkHook {
  66 public:
  67     void mark(void*) { }
  68 };
  69
  70 template<typename MarkHook>
  71 inline void ConservativeRoots::genericAddPointer(void* p, TinyBloomFilter filter, MarkHook& markHook)
  72 {
  73     markHook.mark(p);
  74
  75     CopiedBlock* block;
  76     if (m_copiedSpace->contains(p, block))
  77         m_copiedSpace->pin(block);
  78
  79     MarkedBlock* candidate = MarkedBlock::blockFor(p);
  80     if (filter.ruleOut(reinterpret_cast<Bits>(candidate))) {
  81         ASSERT(!candidate || !m_blocks->set().contains(candidate));
  82         return;
  83     }
  84
  85     if (!MarkedBlock::isAtomAligned(p))
  86         return;
  87
  88     if (!m_blocks->set().contains(candidate))
  89         return;
  90
  91     if (!candidate->isLiveCell(p))
  92         return;
  93
  94     if (m_size == m_capacity)
  95         grow();
  96
  97     m_roots[m_size++] = static_cast<JSCell*>(p);
  98 }
  99
 100 template<typename MarkHook>
 101 void ConservativeRoots::genericAddSpan(void* begin, void* end, MarkHook& markHook)
 102 {
 103     ASSERT(begin <= end);
 104     ASSERT((static_cast<char*>(end) - static_cast<char*>(begin)) < 0x1000000);
 105     ASSERT(isPointerAligned(begin));
 106     ASSERT(isPointerAligned(end));
 107
 108     TinyBloomFilter filter = m_blocks->filter(); // Make a local copy of filter to show the compiler it won't alias, and can be register-allocated.
 109     for (char** it = static_cast<char**>(begin); it != static_cast<char**>(end); ++it)
 110         genericAddPointer(*it, filter, markHook);
 111 }
 112
 113 void ConservativeRoots::add(void* begin, void* end)
 114 {
 115     DummyMarkHook hook;
 116     genericAddSpan(begin, end, hook);
 117 }
 118
 119 void ConservativeRoots::add(void* begin, void* end, DFGCodeBlocks& dfgCodeBlocks)
 120 {
 121     genericAddSpan(begin, end, dfgCodeBlocks);
 122 }
 123
 124 } // namespace JSC