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Fix Half comparison #39773

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merged 3 commits into from
Jul 27, 2020
Merged

Fix Half comparison #39773

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9378edf
Fix Half comparison
Gnbrkm41 Jul 22, 2020
a1819fa
Add parentheses for clarity
Gnbrkm41 Jul 23, 2020
bc61692
Add tests validating comparison between negative numbers for Single/D…
Gnbrkm41 Jul 23, 2020
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4 changes: 2 additions & 2 deletions src/libraries/System.Private.CoreLib/src/System/Half.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -116,7 +116,7 @@ private ushort Significand
// says they should be equal, even if the signs differ.
return leftIsNegative && !AreZero(left, right);
}
return (short)(left._value) < (short)(right._value);
return left._value < right._value ^ leftIsNegative;
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Just for reference, here is the lt implementation: https://github.com/ucb-bar/berkeley-softfloat-3/blob/master/source/f16_lt_quiet.c

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Looks like it's pretty much the same.

}

public static bool operator >(Half left, Half right)
Expand All @@ -141,7 +141,7 @@ private ushort Significand
// says they should be equal, even if the signs differ.
return leftIsNegative || AreZero(left, right);
}
return (short)(left._value) <= (short)(right._value);
return left._value <= right._value ^ leftIsNegative;
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}

public static bool operator >=(Half left, Half right)
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4 changes: 4 additions & 0 deletions src/libraries/System.Runtime/tests/System/HalfTests.cs
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Expand Up @@ -281,6 +281,10 @@ public static IEnumerable<object[]> CompareTo_TestData()
yield return new object[] { Half.NaN, Half.NaN, 0 };
yield return new object[] { Half.NaN, UInt16BitsToHalf(0x0000), -1 };
yield return new object[] { Half.MaxValue, null, 1 };
yield return new object[] { Half.MinValue, Half.NegativeInfinity, 1 };
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yield return new object[] { Half.NegativeInfinity, Half.MinValue, -1 };
yield return new object[] { UInt16BitsToHalf(0x8000), Half.NegativeInfinity, 1 }; // Negative zero
yield return new object[] { Half.NegativeInfinity, UInt16BitsToHalf(0x8000), -1 }; // Negative zero
}

[Theory]
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