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diff --git a/Source/JavaScriptCore/dfg/DFGArithMode.h b/Source/JavaScriptCore/dfg/DFGArithMode.h
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+++ b/Source/JavaScriptCore/dfg/DFGArithMode.h
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+/*
+ * Copyright (C) 2014 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 DFGArithMode_h
+#define DFGArithMode_h
+
+#if ENABLE(DFG_JIT)
+
+namespace JSC { namespace DFG {
+
+// Arith::Mode describes the mode of an arithmetic operation that speculates integer.
+// Note that not all modes are valid for all operations.
+namespace Arith {
+enum Mode {
+    NotSet, // Arithmetic mode is either not relevant because we're using doubles anyway or we are at a phase in compilation where we don't know what we're doing, yet. Should never see this after FixupPhase except for nodes that take doubles as inputs already.
+    Unchecked, // Don't check anything and just do the direct hardware operation.
+    CheckOverflow, // Check for overflow but don't bother with negative zero.
+    CheckOverflowAndNegativeZero, // Check for both overflow and negative zero.
+    DoOverflow // Up-convert to the smallest type that soundly represents all possible results after input type speculation.
+};
+
+// Define the type of operation the rounding operation will perform.
+enum class RoundingMode {
+    Int32, // The round operation produces a integer and -0 is considered as 0.
+    Int32WithNegativeZeroCheck, // The round operation produces a integer and checks for -0.
+    Double // The round operation produce a double. The result can be -0, NaN or (+/-)Infinity.
+};
+
+} // namespace Arith
+
+inline bool doesOverflow(Arith::Mode mode)
+{
+    switch (mode) {
+    case Arith::NotSet:
+        ASSERT_NOT_REACHED();
+#if ASSERT_DISABLED
+        FALLTHROUGH;
+#endif
+    case Arith::Unchecked:
+    case Arith::CheckOverflow:
+    case Arith::CheckOverflowAndNegativeZero:
+        return false;
+    case Arith::DoOverflow:
+        return true;
+    }
+    ASSERT_NOT_REACHED();
+    return true;
+}
+
+// It's only valid to call this once you've determined that you don't need to *do*
+// overflow. For most nodes, that's implicit.
+inline bool shouldCheckOverflow(Arith::Mode mode)
+{
+    switch (mode) {
+    case Arith::NotSet:
+    case Arith::DoOverflow:
+        ASSERT_NOT_REACHED();
+        return true;
+    case Arith::Unchecked:
+        return false;
+    case Arith::CheckOverflow:
+    case Arith::CheckOverflowAndNegativeZero:
+        return true;
+    }
+    ASSERT_NOT_REACHED();
+    return true;
+}
+
+inline bool shouldCheckNegativeZero(Arith::Mode mode)
+{
+    switch (mode) {
+    case Arith::NotSet:
+    case Arith::DoOverflow:
+        ASSERT_NOT_REACHED();
+        return true;
+    case Arith::Unchecked:
+    case Arith::CheckOverflow:
+        return false;
+    case Arith::CheckOverflowAndNegativeZero:
+        return true;
+    }
+    ASSERT_NOT_REACHED();
+    return true;
+}
+
+inline bool subsumes(Arith::Mode earlier, Arith::Mode later)
+{
+    switch (earlier) {
+    case Arith::CheckOverflow:
+        switch (later) {
+        case Arith::Unchecked:
+        case Arith::CheckOverflow:
+            return true;
+        default:
+            return false;
+        }
+    case Arith::CheckOverflowAndNegativeZero:
+        switch (later) {
+        case Arith::Unchecked:
+        case Arith::CheckOverflow:
+        case Arith::CheckOverflowAndNegativeZero:
+            return true;
+        default:
+            return false;
+        }
+    default:
+        return earlier == later;
+    }
+}
+
+inline bool producesInteger(Arith::RoundingMode mode)
+{
+    return mode == Arith::RoundingMode::Int32WithNegativeZeroCheck || mode == Arith::RoundingMode::Int32;
+}
+
+inline bool shouldCheckNegativeZero(Arith::RoundingMode mode)
+{
+    return mode == Arith::RoundingMode::Int32WithNegativeZeroCheck;
+}
+
+} } // namespace JSC::DFG
+
+namespace WTF {
+
+class PrintStream;
+void printInternal(PrintStream&, JSC::DFG::Arith::Mode);
+void printInternal(PrintStream&, JSC::DFG::Arith::RoundingMode);
+
+} // namespace WTF
+
+#endif // ENABLE(DFG_JIT)
+
+#endif // DFGArithMode_h
+