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diff --git a/Source/JavaScriptCore/runtime/PureNaN.h b/Source/JavaScriptCore/runtime/PureNaN.h
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--- a/Source/JavaScriptCore/runtime/PureNaN.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 PureNaN_h
-#define PureNaN_h
-
-#include <wtf/Assertions.h>
-#include <wtf/StdLibExtras.h>
-
-namespace JSC {
-
-// NaN (not-a-number) double values are central to how JavaScriptCore encodes JavaScript
-// values (JSValues).  All values, including integers and non-numeric values, are always
-// encoded using the IEEE 854 binary double format.  Non-double values are encoded using
-// a NaN with the sign bit set.  The 51-bit payload is then used for encoding the actual
-// value - be it an integer or a pointer to an object, or something else. But we only
-// make use of the low 49 bits and the top 15 bits being all set to 1 is the indicator
-// that a value is not a double. Top 15 bits being set to 1 also indicate a signed
-// signaling NaN with some additional NaN payload bits.
-//
-// Our use of NaN encoding means that we have to be careful with how we use NaNs for
-// ordinary doubles. For example, it would be wrong to ever use a NaN that has the top
-// 15 bits set, as that would look like a non-double value to JSC.
-//
-// We can trust that on all of the hardware/OS combinations that we care about,
-// NaN-producing math operations never produce a NaN that looks like a tagged value. But
-// if we're ever in a situation where we worry about it, we can use purifyNaN() to get a
-// NaN that doesn't look like a tagged non-double value. The JavaScript language doesn't
-// distinguish between different flavors of NaN and there is no way to detect what kind
-// of NaN you have - hence so long as all double NaNs are purified then our tagging
-// scheme remains sound.
-//
-// It's worth noting that there are cases, like sin(), that will almost produce a NaN
-// that breaks us. sin(-inf) returns 0xfff8000000000000. This doesn't break us because
-// not all of the top 15 bits are set. But it's very close. Hence our assumptions about
-// NaN are just about the most aggressive assumptions we could possibly make without
-// having to call purifyNaN() in surprising places.
-//
-// For naming purposes, we say that a NaN is "pure" if it is safe to tag, in the sense
-// that doing so would result in a tagged value that would pass the "are you a double"
-// test. We say that a NaN is "impure" if attempting to tag it would result in a value
-// that would look like something other than a double.
-
-// Returns some kind of pure NaN.
-inline double pureNaN()
-{
-    // Be sure that we return exactly the kind of NaN that is safe. We engineer the bits
-    // ourselves to ensure that it's !isImpureNaN(). FWIW, this is what
-    // numeric_limits<double>::quiet_NaN() returns on Mac/X86_64. But AFAICT there is
-    // no guarantee that quiet_NaN would return a pureNaN on all platforms. For example,
-    // the docs appear to imply that quiet_NaN could even return a double with the
-    // signaling bit set on hardware that doesn't do signaling. That would probably
-    // never happen, but it's healthy to be paranoid.
-    return bitwise_cast<double>(0x7ff8000000000000ll);
-}
-
-#define PNaN (pureNaN())
-
-inline bool isImpureNaN(double value)
-{
-    // Tests if the double value would break JSVALUE64 encoding, which is the most
-    // aggressive kind of encoding that we currently use.
-    return bitwise_cast<uint64_t>(value) >= 0xfffe000000000000llu;
-}
-
-// If the given value is NaN then return a NaN that is known to be pure.
-inline double purifyNaN(double value)
-{
-    if (value != value)
-        return PNaN;
-    return value;
-}   
-
-} // namespace JSC
-
-#endif // PureNaN_h