JavaScriptCore/runtime/MarkStack.h

   1 /*
   2  * Copyright (C) 2009 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 MarkStack_h
  27 #define MarkStack_h
  28
  29 #include "JSValue.h"
  30 #include <wtf/Noncopyable.h>
  31
  32 namespace JSC {
  33
  34     class JSGlobalData;
  35     class Register;
  36
  37     enum MarkSetProperties { MayContainNullValues, NoNullValues };
  38
  39     class MarkStack : Noncopyable {
  40     public:
  41         MarkStack(void* jsArrayVPtr)
  42             : m_jsArrayVPtr(jsArrayVPtr)
  43 #ifndef NDEBUG
  44             , m_isCheckingForDefaultMarkViolation(false)
  45 #endif
  46         {
  47         }
  48
  49         ALWAYS_INLINE void append(JSValue);
  50         void append(JSCell*);
  51
  52         ALWAYS_INLINE void appendValues(Register* values, size_t count, MarkSetProperties properties = NoNullValues)
  53         {
  54             appendValues(reinterpret_cast<JSValue*>(values), count, properties);
  55         }
  56
  57         ALWAYS_INLINE void appendValues(JSValue* values, size_t count, MarkSetProperties properties = NoNullValues)
  58         {
  59             if (count)
  60                 m_markSets.append(MarkSet(values, values + count, properties));
  61         }
  62
  63         inline void drain();
  64         void compact();
  65
  66         ~MarkStack()
  67         {
  68             ASSERT(m_markSets.isEmpty());
  69             ASSERT(m_values.isEmpty());
  70         }
  71
  72     private:
  73         void markChildren(JSCell*);
  74
  75         struct MarkSet {
  76             MarkSet(JSValue* values, JSValue* end, MarkSetProperties properties)
  77                 : m_values(values)
  78                 , m_end(end)
  79                 , m_properties(properties)
  80             {
  81                 ASSERT(values);
  82             }
  83             JSValue* m_values;
  84             JSValue* m_end;
  85             MarkSetProperties m_properties;
  86         };
  87
  88         static void* allocateStack(size_t size);
  89         static void releaseStack(void* addr, size_t size);
  90
  91         static void initializePagesize();
  92         static size_t pageSize()
  93         {
  94             if (!s_pageSize)
  95                 initializePagesize();
  96             return s_pageSize;
  97         }
  98
  99         template <typename T> struct MarkStackArray {
 100             MarkStackArray()
 101                 : m_top(0)
 102                 , m_allocated(MarkStack::pageSize())
 103                 , m_capacity(m_allocated / sizeof(T))
 104             {
 105                 m_data = reinterpret_cast<T*>(allocateStack(m_allocated));
 106             }
 107
 108             ~MarkStackArray()
 109             {
 110                 releaseStack(m_data, m_allocated);
 111             }
 112
 113             void expand()
 114             {
 115                 size_t oldAllocation = m_allocated;
 116                 m_allocated *= 2;
 117                 m_capacity = m_allocated / sizeof(T);
 118                 void* newData = allocateStack(m_allocated);
 119                 memcpy(newData, m_data, oldAllocation);
 120                 releaseStack(m_data, oldAllocation);
 121                 m_data = reinterpret_cast<T*>(newData);
 122             }
 123
 124             inline void append(const T& v)
 125             {
 126                 if (m_top == m_capacity)
 127                     expand();
 128                 m_data[m_top++] = v;
 129             }
 130
 131             inline T removeLast()
 132             {
 133                 ASSERT(m_top);
 134                 return m_data[--m_top];
 135             }
 136
 137             inline T& last()
 138             {
 139                 ASSERT(m_top);
 140                 return m_data[m_top - 1];
 141             }
 142
 143             inline bool isEmpty()
 144             {
 145                 return m_top == 0;
 146             }
 147
 148             inline size_t size() { return m_top; }
 149
 150             inline void shrinkAllocation(size_t size)
 151             {
 152                 ASSERT(size <= m_allocated);
 153                 ASSERT(0 == (size % MarkStack::pageSize()));
 154                 if (size == m_allocated)
 155                     return;
 156 #if PLATFORM(WIN_OS) || PLATFORM(SYMBIAN)
 157                 // We cannot release a part of a region with VirtualFree.  To get around this,
 158                 // we'll release the entire region and reallocate the size that we want.
 159                 releaseStack(m_data, m_allocated);
 160                 m_data = reinterpret_cast<T*>(allocateStack(size));
 161 #else
 162                 releaseStack(reinterpret_cast<char*>(m_data) + size, m_allocated - size);
 163 #endif
 164                 m_allocated = size;
 165                 m_capacity = m_allocated / sizeof(T);
 166             }
 167
 168         private:
 169             size_t m_top;
 170             size_t m_allocated;
 171             size_t m_capacity;
 172             T* m_data;
 173         };
 174
 175         void* m_jsArrayVPtr;
 176         MarkStackArray<MarkSet> m_markSets;
 177         MarkStackArray<JSCell*> m_values;
 178         static size_t s_pageSize;
 179
 180 #ifndef NDEBUG
 181     public:
 182         bool m_isCheckingForDefaultMarkViolation;
 183 #endif
 184     };
 185 }
 186
 187 #endif