Remove redundant argument cloning.

lib/Differentiator/ReverseModeVisitor.cpp

@@ -1888,17 +1888,6 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
       m_ExternalSource->ActBeforeFinalizingVisitCallExpr(
         CE, OverloadedDerivedFn, DerivedCallArgs, ArgResultDecls, asGrad);
 
-    // FIXME: Why are we cloning args here? We already created different
-    // expressions for call to original function and call to gradient.
-    // Re-clone function arguments again, since they are required at 2 places:
-    // call to gradient and call to original function. At this point, each arg
-    // is either a simple expression or a reference to a temporary variable.
-    // Therefore cloning it has constant complexity.
-    std::transform(std::begin(CallArgs),
-                   std::end(CallArgs),
-                   std::begin(CallArgs),
-                   [this](Expr* E) { return Clone(E); });
-
     Expr* call = nullptr;
 
     if (FD->getReturnType()->isReferenceType()) {