dfg/DFGByteCodeCache.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 DFGByteCodeCache_h
  27 #define DFGByteCodeCache_h
  28
  29 #include <wtf/Platform.h>
  30
  31 #if ENABLE(DFG_JIT)
  32
  33 #include "CodeBlock.h"
  34 #include "Executable.h"
  35 #include "JSFunction.h"
  36 #include <wtf/HashMap.h>
  37
  38 namespace JSC { namespace DFG {
  39
  40 class CodeBlockKey {
  41 public:
  42     CodeBlockKey()
  43         : m_executable(0)
  44         , m_kind(CodeForCall) // CodeForCall = empty value
  45     {
  46     }
  47
  48     CodeBlockKey(WTF::HashTableDeletedValueType)
  49         : m_executable(0)
  50         , m_kind(CodeForConstruct) // CodeForConstruct = deleted value
  51     {
  52     }
  53
  54     CodeBlockKey(FunctionExecutable* executable, CodeSpecializationKind kind)
  55         : m_executable(executable)
  56         , m_kind(kind)
  57     {
  58     }
  59
  60     bool operator==(const CodeBlockKey& other) const
  61     {
  62         return m_executable == other.m_executable
  63             && m_kind == other.m_kind;
  64     }
  65
  66     unsigned hash() const
  67     {
  68         return WTF::PtrHash<FunctionExecutable*>::hash(m_executable) ^ static_cast<unsigned>(m_kind);
  69     }
  70
  71     FunctionExecutable* executable() const { return m_executable; }
  72     CodeSpecializationKind kind() const { return m_kind; }
  73
  74     bool isHashTableDeletedValue() const
  75     {
  76         return !m_executable && m_kind == CodeForConstruct;
  77     }
  78
  79 private:
  80     FunctionExecutable* m_executable;
  81     CodeSpecializationKind m_kind;
  82 };
  83
  84 struct CodeBlockKeyHash {
  85     static unsigned hash(const CodeBlockKey& key) { return key.hash(); }
  86     static bool equal(const CodeBlockKey& a, const CodeBlockKey& b) { return a == b; }
  87
  88     static const bool safeToCompareToEmptyOrDeleted = true;
  89 };
  90
  91 } } // namespace JSC::DFG
  92
  93 namespace WTF {
  94
  95 template<typename T> struct DefaultHash;
  96 template<> struct DefaultHash<JSC::DFG::CodeBlockKey> {
  97     typedef JSC::DFG::CodeBlockKeyHash Hash;
  98 };
  99
 100 template<typename T> struct HashTraits;
 101 template<> struct HashTraits<JSC::DFG::CodeBlockKey> : SimpleClassHashTraits<JSC::DFG::CodeBlockKey> { };
 102
 103 } // namespace WTF
 104
 105 namespace JSC { namespace DFG {
 106
 107 struct ByteCodeCacheValue {
 108     FunctionCodeBlock* codeBlock;
 109     bool owned;
 110     bool oldValueOfShouldDiscardBytecode;
 111
 112     // All uses of this struct initialize everything manually. But gcc isn't
 113     // smart enough to see that, so this constructor is just here to make the
 114     // compiler happy.
 115     ByteCodeCacheValue()
 116         : codeBlock(0)
 117         , owned(false)
 118         , oldValueOfShouldDiscardBytecode(false)
 119     {
 120     }
 121 };
 122
 123 template<bool (*filterFunction)(CodeBlock*, CodeSpecializationKind)>
 124 class ByteCodeCache {
 125 public:
 126     typedef HashMap<CodeBlockKey, ByteCodeCacheValue> Map;
 127
 128     ByteCodeCache() { }
 129
 130     ~ByteCodeCache()
 131     {
 132         Map::iterator begin = m_map.begin();
 133         Map::iterator end = m_map.end();
 134         for (Map::iterator iter = begin; iter != end; ++iter) {
 135             if (!iter->second.codeBlock)
 136                 continue;
 137             if (iter->second.owned) {
 138                 delete iter->second.codeBlock;
 139                 continue;
 140             }
 141         }
 142     }
 143
 144     CodeBlock* get(const CodeBlockKey& key, ScopeChainNode* scope)
 145     {
 146         Map::iterator iter = m_map.find(key);
 147         if (iter != m_map.end())
 148             return iter->second.codeBlock;
 149
 150         ByteCodeCacheValue value;
 151
 152         // First see if there is already a parsed code block that still has some
 153         // bytecode in it.
 154         value.codeBlock = key.executable()->codeBlockWithBytecodeFor(key.kind());
 155         if (value.codeBlock) {
 156             value.owned = false;
 157         } else {
 158             // Nope, so try to parse one.
 159             JSObject* exception;
 160             value.owned = true;
 161             value.codeBlock = key.executable()->produceCodeBlockFor(scope, OptimizingCompilation, key.kind(), exception).leakPtr();
 162         }
 163
 164         // Check if there is any reason to reject this from our cache. If so, then
 165         // poison it.
 166         if (!!value.codeBlock && !filterFunction(value.codeBlock, key.kind())) {
 167             if (value.owned)
 168                 delete value.codeBlock;
 169             value.codeBlock = 0;
 170         }
 171
 172         m_map.add(key, value);
 173
 174         return value.codeBlock;
 175     }
 176
 177 private:
 178     Map m_map;
 179 };
 180
 181 } } // namespace JSC::DFG
 182
 183 #endif // ENABLE(DFG_JIT)
 184
 185 #endif // DFGByteCodeCache_h