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 "CodeBlock.h"
  30 #include "CodeBlockSet.h"
  31 #include "CopiedSpace.h"
  32 #include "CopiedSpaceInlines.h"
  33 #include "JSCell.h"
  34 #include "JSObject.h"
  35 #include "JSCInlines.h"
  36 #include "Structure.h"
  37
  38 namespace JSC {
  39
  40 ConservativeRoots::ConservativeRoots(const MarkedBlockSet* blocks, CopiedSpace* copiedSpace)
  41     : m_roots(m_inlineRoots)
  42     , m_size(0)
  43     , m_capacity(inlineCapacity)
  44     , m_blocks(blocks)
  45     , m_copiedSpace(copiedSpace)
  46 {
  47 }
  48
  49 ConservativeRoots::~ConservativeRoots()
  50 {
  51     if (m_roots != m_inlineRoots)
  52         OSAllocator::decommitAndRelease(m_roots, m_capacity * sizeof(JSCell*));
  53 }
  54
  55 void ConservativeRoots::grow()
  56 {
  57     size_t newCapacity = m_capacity == inlineCapacity ? nonInlineCapacity : m_capacity * 2;
  58     JSCell** newRoots = static_cast<JSCell**>(OSAllocator::reserveAndCommit(newCapacity * sizeof(JSCell*)));
  59     memcpy(newRoots, m_roots, m_size * sizeof(JSCell*));
  60     if (m_roots != m_inlineRoots)
  61         OSAllocator::decommitAndRelease(m_roots, m_capacity * sizeof(JSCell*));
  62     m_capacity = newCapacity;
  63     m_roots = newRoots;
  64 }
  65
  66 template<typename MarkHook>
  67 inline void ConservativeRoots::genericAddPointer(void* p, TinyBloomFilter filter, MarkHook& markHook)
  68 {
  69     markHook.mark(p);
  70
  71     m_copiedSpace->pinIfNecessary(p);
  72
  73     MarkedBlock* candidate = MarkedBlock::blockFor(p);
  74     if (filter.ruleOut(reinterpret_cast<Bits>(candidate))) {
  75         ASSERT(!candidate || !m_blocks->set().contains(candidate));
  76         return;
  77     }
  78
  79     if (!MarkedBlock::isAtomAligned(p))
  80         return;
  81
  82     if (!m_blocks->set().contains(candidate))
  83         return;
  84
  85     if (!candidate->isLiveCell(p))
  86         return;
  87
  88     if (m_size == m_capacity)
  89         grow();
  90
  91     m_roots[m_size++] = static_cast<JSCell*>(p);
  92 }
  93
  94 template<typename MarkHook>
  95 void ConservativeRoots::genericAddSpan(void* begin, void* end, MarkHook& markHook)
  96 {
  97     if (begin > end) {
  98         void* swapTemp = begin;
  99         begin = end;
 100         end = swapTemp;
 101     }
 102
 103     RELEASE_ASSERT(isPointerAligned(begin));
 104     RELEASE_ASSERT(isPointerAligned(end));
 105
 106     TinyBloomFilter filter = m_blocks->filter(); // Make a local copy of filter to show the compiler it won't alias, and can be register-allocated.
 107     for (char** it = static_cast<char**>(begin); it != static_cast<char**>(end); ++it)
 108         genericAddPointer(*it, filter, markHook);
 109 }
 110
 111 class DummyMarkHook {
 112 public:
 113     void mark(void*) { }
 114 };
 115
 116 void ConservativeRoots::add(void* begin, void* end)
 117 {
 118     DummyMarkHook dummy;
 119     genericAddSpan(begin, end, dummy);
 120 }
 121
 122 void ConservativeRoots::add(void* begin, void* end, JITStubRoutineSet& jitStubRoutines)
 123 {
 124     genericAddSpan(begin, end, jitStubRoutines);
 125 }
 126
 127 template<typename T, typename U>
 128 class CompositeMarkHook {
 129 public:
 130     CompositeMarkHook(T& first, U& second)
 131         : m_first(first)
 132         , m_second(second)
 133     {
 134     }
 135
 136     void mark(void* address)
 137     {
 138         m_first.mark(address);
 139         m_second.mark(address);
 140     }
 141
 142 private:
 143     T& m_first;
 144     U& m_second;
 145 };
 146
 147 void ConservativeRoots::add(
 148     void* begin, void* end, JITStubRoutineSet& jitStubRoutines, CodeBlockSet& codeBlocks)
 149 {
 150     CompositeMarkHook<JITStubRoutineSet, CodeBlockSet> markHook(jitStubRoutines, codeBlocks);
 151     genericAddSpan(begin, end, markHook);
 152 }
 153
 154 } // namespace JSC