Imported WebKit commit 2ea9d364d0f6efa8fa64acf19f451504c59be0e4 (http://svn.webkit.org/repository/webkit/trunk@104285)

1 files changed, 194 insertions, 0 deletions

diff --git a/Source/JavaScriptCore/dfg/DFGByteCodeCache.h b/Source/JavaScriptCore/dfg/DFGByteCodeCache.h
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+++ b/Source/JavaScriptCore/dfg/DFGByteCodeCache.h
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+/*
+ * Copyright (C) 2011 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+ */
+
+#ifndef DFGByteCodeCache_h
+#define DFGByteCodeCache_h
+
+#include <wtf/Platform.h>
+
+#if ENABLE(DFG_JIT)
+
+#include "CodeBlock.h"
+#include "Executable.h"
+#include "JSFunction.h"
+#include <wtf/HashMap.h>
+
+namespace JSC { namespace DFG {
+
+class CodeBlockKey {
+public:
+    CodeBlockKey()
+        : m_executable(0)
+        , m_kind(CodeForCall) // CodeForCall = empty value
+    {
+    }
+    
+    CodeBlockKey(WTF::HashTableDeletedValueType)
+        : m_executable(0)
+        , m_kind(CodeForConstruct) // CodeForConstruct = deleted value
+    {
+    }
+    
+    CodeBlockKey(FunctionExecutable* executable, CodeSpecializationKind kind)
+        : m_executable(executable)
+        , m_kind(kind)
+    {
+    }
+    
+    bool operator==(const CodeBlockKey& other) const
+    {
+        return m_executable == other.m_executable
+            && m_kind == other.m_kind;
+    }
+    
+    unsigned hash() const
+    {
+        return WTF::PtrHash<FunctionExecutable*>::hash(m_executable) ^ static_cast<unsigned>(m_kind);
+    }
+    
+    FunctionExecutable* executable() const { return m_executable; }
+    CodeSpecializationKind kind() const { return m_kind; }
+
+    bool isHashTableDeletedValue() const
+    {
+        return !m_executable && m_kind == CodeForConstruct;
+    }
+
+private:
+    FunctionExecutable* m_executable;
+    CodeSpecializationKind m_kind;
+};
+
+struct CodeBlockKeyHash {
+    static unsigned hash(const CodeBlockKey& key) { return key.hash(); }
+    static bool equal(const CodeBlockKey& a, const CodeBlockKey& b) { return a == b; }
+    
+    static const bool safeToCompareToEmptyOrDeleted = true;
+};
+
+} } // namespace JSC::DFG
+
+namespace WTF {
+
+template<typename T> struct DefaultHash;
+template<> struct DefaultHash<JSC::DFG::CodeBlockKey> {
+    typedef JSC::DFG::CodeBlockKeyHash Hash;
+};
+
+template<typename T> struct HashTraits;
+template<> struct HashTraits<JSC::DFG::CodeBlockKey> : SimpleClassHashTraits<JSC::DFG::CodeBlockKey> { };
+
+} // namespace WTF
+
+namespace JSC { namespace DFG {
+
+struct ByteCodeCacheValue {
+    FunctionCodeBlock* codeBlock;
+    bool owned;
+    bool oldValueOfShouldDiscardBytecode;
+    
+    // All uses of this struct initialize everything manually. But gcc isn't
+    // smart enough to see that, so this constructor is just here to make the
+    // compiler happy.
+    ByteCodeCacheValue()
+        : codeBlock(0)
+        , owned(false)
+        , oldValueOfShouldDiscardBytecode(false)
+    {
+    }
+};
+
+template<bool (*filterFunction)(CodeBlock*, CodeSpecializationKind)>
+class ByteCodeCache {
+public:
+    typedef HashMap<CodeBlockKey, ByteCodeCacheValue> Map;
+    
+    ByteCodeCache() { }
+    
+    ~ByteCodeCache()
+    {
+        Map::iterator begin = m_map.begin();
+        Map::iterator end = m_map.end();
+        for (Map::iterator iter = begin; iter != end; ++iter) {
+            if (!iter->second.codeBlock)
+                continue;
+            if (iter->second.owned) {
+                delete iter->second.codeBlock;
+                continue;
+            }
+            iter->second.codeBlock->m_shouldDiscardBytecode = iter->second.oldValueOfShouldDiscardBytecode;
+        }
+    }
+    
+    CodeBlock* get(const CodeBlockKey& key, ScopeChainNode* scope)
+    {
+        Map::iterator iter = m_map.find(key);
+        if (iter != m_map.end())
+            return iter->second.codeBlock;
+        
+        ByteCodeCacheValue value;
+        
+        // First see if there is already a parsed code block that still has some
+        // bytecode in it.
+        value.codeBlock = key.executable()->codeBlockWithBytecodeFor(key.kind());
+        if (value.codeBlock) {
+            value.owned = false;
+            value.oldValueOfShouldDiscardBytecode = value.codeBlock->m_shouldDiscardBytecode;
+        } else {
+            // Nope, so try to parse one.
+            JSObject* exception;
+            value.owned = true;
+            value.codeBlock = key.executable()->produceCodeBlockFor(scope, OptimizingCompilation, key.kind(), exception).leakPtr();
+        }
+        
+        // Check if there is any reason to reject this from our cache. If so, then
+        // poison it.
+        if (!!value.codeBlock && !filterFunction(value.codeBlock, key.kind())) {
+            if (value.owned)
+                delete value.codeBlock;
+            value.codeBlock = 0;
+        }
+        
+        // If we're about to return a code block, make sure that we're not going
+        // to be discarding its bytecode if a GC were to happen during DFG
+        // compilation. That's unlikely, but it's good to thoroughly enjoy this
+        // kind of paranoia.
+        if (!!value.codeBlock)
+            value.codeBlock->m_shouldDiscardBytecode = false;
+        
+        m_map.add(key, value);
+        
+        return value.codeBlock;
+    }
+
+private:
+    Map m_map;
+};
+
+} } // namespace JSC::DFG
+
+#endif // ENABLE(DFG_JIT)
+
+#endif // DFGByteCodeCache_h