Imported WebKit commit bb52bf3c0119e8a128cd93afe5572413a8617de9 (http://svn.webkit.org/repository/webkit/trunk@108790)

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diff --git a/Source/JavaScriptCore/dfg/DFGArithNodeFlagsInferencePhase.h b/Source/JavaScriptCore/dfg/DFGArithNodeFlagsInferencePhase.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 DFGArithNodeFlagsInferencePhase_h
+#define DFGArithNodeFlagsInferencePhase_h
+
+#include <wtf/Platform.h>
+
+#if ENABLE(DFG_JIT)
+
+namespace JSC { namespace DFG {
+
+class Graph;
+
+// Determine which arithmetic nodes' results are only used in a context that
+// truncates to integer anyway. This is great for optimizing away checks for
+// overflow and negative zero. NB the way this phase integrates into the rest
+// of the DFG makes it non-optional. Instead of proving that a node is only
+// used in integer context, it actually does the opposite: finds nodes that
+// are used in non-integer contexts. Hence failing to run this phase will make
+// the compiler assume that all nodes are just used as integers!
+
+void performArithNodeFlagsInference(Graph&);
+
+} } // namespace JSC::DFG::Phase
+
+#endif // ENABLE(DFG_JIT)
+
+#endif // DFGArithNodeFlagsInferencePhase_h