!fixup use dyn_cast

Author: fhahn

llvm/lib/Transforms/Utils/Evaluator.cpp

@@ -74,13 +74,12 @@ isSimpleEnoughValueToCommitHelper(Constant *C,
     return true;
   }
 
-  if (isa<ConstantPtrAuth>(C))
-    return false;
-
   // We don't know exactly what relocations are allowed in constant expressions,
   // so we allow &global+constantoffset, which is safe and uniformly supported
   // across targets.
-  ConstantExpr *CE = cast<ConstantExpr>(C);
+  ConstantExpr *CE = dyn_cast<ConstantExpr>(C);
+  if (!CE)
+    return false;
   switch (CE->getOpcode()) {
   case Instruction::BitCast:
     // Bitcast is fine if the casted value is fine.