Imported WebKit commit 3a8c29f35d00659d2ce7a0ccdfa8304f14e82327 (http://svn.webkit.org/repository/webkit/trunk@120813)

New snapshot with Windows build fixes

1 files changed, 101 insertions, 0 deletions

diff --git a/Source/JavaScriptCore/runtime/JSSegmentedVariableObject.h b/Source/JavaScriptCore/runtime/JSSegmentedVariableObject.h
new file mode 100644
index 000000000..f1fe0483d
--- /dev/null
+++ b/Source/JavaScriptCore/runtime/JSSegmentedVariableObject.h
@@ -0,0 +1,101 @@
+/*
+ * Copyright (C) 2012 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 Computer, 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 JSSegmentedVariableObject_h
+#define JSSegmentedVariableObject_h
+
+#include "JSObject.h"
+#include "JSSymbolTableObject.h"
+#include "Register.h"
+#include "SymbolTable.h"
+#include <wtf/OwnArrayPtr.h>
+#include <wtf/SegmentedVector.h>
+#include <wtf/UnusedParam.h>
+
+namespace JSC {
+
+class LLIntOffsetsExtractor;
+class Register;
+
+// This is a mostly drop-in replacement for JSVariableObject, except that it preserves
+// the invariant that after a variable is created, its address in memory will not change
+// so long as the JSSegmentedVariableObject is alive. This allows optimizations based
+// on getting the address of the variable and remembering it. As well, unlike a
+// JSVariableObject, this will manage the memory for the registers itself and neither
+// requires nor allows for the subclasses to manage that memory. Finally,
+// JSSegmentedVariableObject has its own GC tracing functionality, since it knows the
+// exact dimensions of the variables array at all times.
+
+class JSSegmentedVariableObject : public JSSymbolTableObject {
+    friend class JIT;
+    friend class LLIntOffsetsExtractor;
+
+public:
+    typedef JSSymbolTableObject Base;
+
+    WriteBarrier<Unknown>& registerAt(int index) { return m_registers[index]; }
+    
+    // This is a slow method call, which searches the register bank to find the index
+    // given a pointer. It will CRASH() if it does not find the register. Only use this
+    // in debug code (like bytecode dumping).
+    JS_EXPORT_PRIVATE int findRegisterIndex(void*);
+    
+    WriteBarrier<Unknown>* assertRegisterIsInThisObject(WriteBarrier<Unknown>* registerPointer)
+    {
+#if !ASSERT_DISABLED
+        findRegisterIndex(registerPointer);
+#endif
+        return registerPointer;
+    }
+    
+    // Adds numberOfRegistersToAdd registers, initializes them to Undefined, and returns
+    // the index of the first one added.
+    JS_EXPORT_PRIVATE int addRegisters(int numberOfRegistersToAdd);
+    
+    JS_EXPORT_PRIVATE static void visitChildren(JSCell*, SlotVisitor&);
+
+protected:
+    static const unsigned StructureFlags = OverridesVisitChildren | JSSymbolTableObject::StructureFlags;
+
+    JSSegmentedVariableObject(JSGlobalData& globalData, Structure* structure, SymbolTable* symbolTable)
+        : JSSymbolTableObject(globalData, structure, symbolTable)
+    {
+    }
+
+    void finishCreation(JSGlobalData& globalData)
+    {
+        Base::finishCreation(globalData);
+    }
+
+    SegmentedVector<WriteBarrier<Unknown>, 16> m_registers;
+};
+
+} // namespace JSC
+
+#endif // JSSegmentedVariableObject_h
+