webkitgtk-2.10.2webkitgtk-2.10.2

1 files changed, 95 insertions, 0 deletions

diff --git a/Source/JavaScriptCore/bytecode/EvalCodeCache.h b/Source/JavaScriptCore/bytecode/EvalCodeCache.h
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+++ b/Source/JavaScriptCore/bytecode/EvalCodeCache.h
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+/*
+ * Copyright (C) 2008, 2009 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.
+ * 3.  Neither the name of Apple Inc. ("Apple") nor the names of
+ *     its contributors may be used to endorse or promote products derived
+ *     from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "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 OR ITS 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 EvalCodeCache_h
+#define EvalCodeCache_h
+
+#include "Executable.h"
+#include "JSGlobalObject.h"
+#include "Options.h"
+#include "SourceCode.h"
+#include <wtf/HashMap.h>
+#include <wtf/RefPtr.h>
+#include <wtf/text/StringHash.h>
+
+namespace JSC {
+
+    class SlotVisitor;
+
+    class EvalCodeCache {
+    public:
+        EvalExecutable* tryGet(bool inStrictContext, const String& evalSource, JSScope* scope)
+        {
+            if (isCacheable(inStrictContext, evalSource, scope))
+                return m_cacheMap.get(evalSource.impl()).get();
+            return 0;
+        }
+        
+        EvalExecutable* getSlow(ExecState* exec, ScriptExecutable* owner, bool inStrictContext, ThisTDZMode thisTDZMode, const String& evalSource, JSScope* scope)
+        {
+            VariableEnvironment variablesUnderTDZ;
+            JSScope::collectVariablesUnderTDZ(scope, variablesUnderTDZ);
+            EvalExecutable* evalExecutable = EvalExecutable::create(exec, makeSource(evalSource), inStrictContext, thisTDZMode, &variablesUnderTDZ);
+            if (!evalExecutable)
+                return 0;
+
+            if (isCacheable(inStrictContext, evalSource, scope) && m_cacheMap.size() < maxCacheEntries)
+                m_cacheMap.set(evalSource.impl(), WriteBarrier<EvalExecutable>(exec->vm(), owner, evalExecutable));
+            
+            return evalExecutable;
+        }
+
+        bool isEmpty() const { return m_cacheMap.isEmpty(); }
+
+        void visitAggregate(SlotVisitor&);
+
+        void clear()
+        {
+            m_cacheMap.clear();
+        }
+
+    private:
+        ALWAYS_INLINE bool isCacheable(bool inStrictContext, const String& evalSource, JSScope* scope) const
+        {
+            // If eval() is called and it has access to a lexical scope, we can't soundly cache it.
+            // If the eval() only has access to the "var" scope, then we can cache it.
+            return !inStrictContext 
+                && evalSource.length() < Options::maximumEvalCacheableSourceLength() 
+                && scope->begin()->isVariableObject()
+                && !scope->isLexicalScope()
+                && !scope->isCatchScope();
+        }
+        static const int maxCacheEntries = 64;
+
+        typedef HashMap<RefPtr<StringImpl>, WriteBarrier<EvalExecutable>> EvalCacheMap;
+        EvalCacheMap m_cacheMap;
+    };
+
+} // namespace JSC
+
+#endif // EvalCodeCache_h