JavaScriptCore-521.tar.gz

[apple/javascriptcore.git] / bytecompiler / Label.h

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+/*
+ * Copyright (C) 2008 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 Label_h
+#define Label_h
+
+#include "CodeBlock.h"
+#include "Instruction.h"
+#include <wtf/Assertions.h>
+#include <wtf/Vector.h>
+#include <limits.h>
+
+namespace JSC {
+
+    class Label {
+    public:
+        explicit Label(CodeBlock* codeBlock)
+            : m_refCount(0)
+            , m_location(invalidLocation)
+            , m_codeBlock(codeBlock)
+        {
+        }
+
+        void setLocation(unsigned location)
+        {
+            m_location = location;
+
+            unsigned size = m_unresolvedJumps.size();
+            for (unsigned i = 0; i < size; ++i) {
+                unsigned j = m_unresolvedJumps[i];
+                m_codeBlock->instructions()[j].u.operand = m_location - j;
+            }
+        }
+
+        int offsetFrom(int location) const
+        {
+            if (m_location == invalidLocation) {
+                m_unresolvedJumps.append(location);
+                return 0;
+            }
+            return m_location - location;
+        }
+
+        void ref() { ++m_refCount; }
+        void deref()
+        {
+            --m_refCount;
+            ASSERT(m_refCount >= 0);
+        }
+        int refCount() const { return m_refCount; }
+
+        bool isForward() const { return m_location == invalidLocation; }
+
+    private:
+        typedef Vector<int, 8> JumpVector;
+
+        static const unsigned invalidLocation = UINT_MAX;
+
+        int m_refCount;
+        unsigned m_location;
+        CodeBlock* m_codeBlock;
+        mutable JumpVector m_unresolvedJumps;
+    };
+
+} // namespace JSC
+
+#endif // Label_h