[llvm] [ValueTracking] Compute known FPClass from signbit idiom (PR #80740)

[Matt Arsenault via llvm-commits]

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@@ -66,6 +66,10 @@ static void findAffectedValues(Value *Cond,
         // A > C3 && A < C4.
         if (match(A, m_Add(m_Value(X), m_ConstantInt())))
           AddAffected(X);
+        // Handle icmp slt/sgt (bitcast X to int), 0/-1
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arsenm wrote:

This comment would be more helpful at the actual use in computeKnownFPClassFromCond

https://github.com/llvm/llvm-project/pull/80740