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Roll back -ffast-math

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Summary:
@public

`-ffast-math` does not have measurable performance benefits.

By using `NaN` for *undefined* values again, we can squeeze `YGFloatOptional` into 32 bits.
This will also enable us to store `YGValue` (or a variant of it) in 32 bits.

Reviewed By: SidharthGuglani

Differential Revision: D13119110

fbshipit-source-id: 4e6964240bf74ebc22d8783107b89d536a1a0842
This commit is contained in:
David Aurelio
2018-12-06 07:35:07 -08:00
committed by Facebook Github Bot
parent b9972cee6e
commit 0962c5220c
7 changed files with 21 additions and 77 deletions
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23
csharp/Facebook.Yoga/YogaConstants.cs
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@@ -1,4 +1,4 @@
/**
/**
* Copyright (c) Facebook, Inc. and its affiliates.
*
* This source code is licensed under the MIT license found in the
@@ -9,28 +9,11 @@ namespace Facebook.Yoga
{
public static class YogaConstants
{
/**
* Large positive number signifies that the property(float) is undefined. Earlier we used to have
* YGundefined as NAN, but the downside of this is that we can't use -ffast-math compiler flag as
* it assumes all floating-point calculation involve and result into finite numbers. For more
* information regarding -ffast-math compiler flag in clang, have a look at
* https://clang.llvm.org/docs/UsersManual.html#cmdoption-ffast-math
*/
public const float Undefined = 10E20F;
public const float Undefined = float.NaN;
public static bool IsUndefined(float value)
{
// Value of a float in the case of it being not defined is 10.1E20. Earlier it used to be NAN,
// the benefit of which
// was that if NAN is involved in any mathematical expression the result was NAN. But since we
// want to have `-ffast-math`
// flag being used by compiler which assumes that the floating point values are not NAN and Inf,
// we represent YGUndefined as 10.1E20.
// But now if YGUndefined is involved in any mathematical operations this value(10.1E20) would
// change.
// So the following check makes sure that if the value is outside a range (-10E8, 10E8) then it
// is undefined.
return value >= 10E8F || value <= -10E8;
return float.IsNaN(value);
}
public static bool IsUndefined(YogaValue value)