JavaScriptCore-1097.3.tar.gz

[apple/javascriptcore.git] / bytecode / MethodOfGettingAValueProfile.h

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+/*
+ * 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.
+ *
+ * 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 MethodOfGettingAValueProfile_h
+#define MethodOfGettingAValueProfile_h
+
+#include <wtf/Platform.h>
+
+// This is guarded by ENABLE_DFG_JIT only because it uses some value profiles
+// that are currently only used if the DFG is enabled (i.e. they are not
+// available in the profile-only configuration). Hopefully someday all of
+// these #if's will disappear...
+#if ENABLE(DFG_JIT)
+
+#include "JSValue.h"
+
+namespace JSC {
+
+class CodeBlock;
+class LazyOperandValueProfileKey;
+struct ValueProfile;
+
+class MethodOfGettingAValueProfile {
+public:
+    MethodOfGettingAValueProfile()
+        : m_kind(None)
+    {
+    }
+    
+    explicit MethodOfGettingAValueProfile(ValueProfile* profile)
+    {
+        if (profile) {
+            m_kind = Ready;
+            u.profile = profile;
+        } else
+            m_kind = None;
+    }
+    
+    static MethodOfGettingAValueProfile fromLazyOperand(
+        CodeBlock*, const LazyOperandValueProfileKey&);
+    
+    bool operator!() const { return m_kind == None; }
+    
+    // This logically has a pointer to a "There exists X such that
+    // ValueProfileBase<X>". But since C++ does not have existential
+    // templates, I cannot return it. So instead, for any methods that
+    // users of this class would like to call, we'll just have to provide
+    // a method here that does it through an indirection. Or we could
+    // possibly just make ValueProfile less template-based. But last I
+    // tried that, it felt more yucky than this class.
+    
+    EncodedJSValue* getSpecFailBucket(unsigned index) const;
+    
+private:
+    enum Kind {
+        None,
+        Ready,
+        LazyOperand
+    };
+    
+    Kind m_kind;
+    union {
+        ValueProfile* profile;
+        struct {
+            CodeBlock* codeBlock;
+            unsigned bytecodeOffset;
+            int operand;
+        } lazyOperand;
+    } u;
+};
+
+} // namespace JSC
+
+#endif // ENABLE(DFG_JIT)
+
+#endif // MethodOfGettingAValueProfile_h
+