[PATCH] D149185: ValueTracking: Fix computeKnownFPClass handling for copysign

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added inline comments.


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Comment at: llvm/include/llvm/Analysis/ValueTracking.h:403
+    if (Sign.isKnownNever(fcPositive | fcNan) || (SignBit && *SignBit))
+      KnownFPClasses &= (fcNegative | fcNan);
+    if (Sign.isKnownNever(fcNegative | fcNan) || (SignBit && !*SignBit))
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foad wrote:
> How do you know the result is not nan?
You don’t. This is avoiding clearing the bits that say it could be nan


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D149185/new/

https://reviews.llvm.org/D149185