In the absence of type feedback, pessimistically force Tagged representation for UnaryAdd

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 4d9bc9bc64ef3b693e59c4d66645873af43a0cbf..d45f320db35d9d2fd0d5108a4aa9ea0587054cb4 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -8613,6 +8613,11 @@ void HOptimizedGraphBuilder::VisitAdd(UnaryOperation* expr) {
   HValue* context = environment()->LookupContext();
   HInstruction* instr =
       HMul::New(zone(), context, value, graph()->GetConstant1());
+  if (instr->IsBinaryOperation()) {
+    // Since we don't have type feedback, we must be cautious/pessimistic.
+    HBinaryOperation::cast(instr)->set_observed_input_representation(
+        Representation::Tagged(), Representation::Tagged());
+  }
   return ast_context()->ReturnInstruction(instr, expr->id());
 }