[llvm] [ValueTracking] Fix incorrect inferrence about the signbit of sqrt (PR #92510)

[Matt Arsenault via llvm-commits]

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@@ -4940,11 +4940,8 @@ void computeKnownFPClass(const Value *V, const APInt &DemandedElts,
       // subnormal input could produce a negative zero output.
       const Function *F = II->getFunction();
       if (Q.IIQ.hasNoSignedZeros(II) ||
-          (F && KnownSrc.isKnownNeverLogicalNegZero(*F, II->getType()))) {
+          (F && KnownSrc.isKnownNeverLogicalNegZero(*F, II->getType())))
         Known.knownNot(fcNegZero);
-        if (KnownSrc.isKnownNeverNaN())
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arsenm wrote:

Semi-related, this should be using propagateNaN instead of repeating the snan logic 

https://github.com/llvm/llvm-project/pull/92510