[llvm] [ValueTracking] Compute known FPClass from dominating condition (PR #80941)

[Matt Arsenault via llvm-commits]

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@@ -69,6 +69,13 @@ static void findAffectedValues(Value *Cond,
       }
     }
   }
+  // Handle patterns that computeKnownFPClass() support.
+  FCmpInst::Predicate Pred;
+  Value *A;
+  if (match(Cond, m_FCmp(Pred, m_Value(A), m_Constant())))
+    AddAffected(A);
+  if (match(Cond, m_Intrinsic<Intrinsic::is_fpclass>(m_Value(A), m_Constant())))
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arsenm wrote:

This can be else if 

https://github.com/llvm/llvm-project/pull/80941