Avoid duplicated constructions of expression

in add_guarded_claim.

Author: petr-bauch

src/analyses/goto_check.cpp

@@ -1474,24 +1474,19 @@ void goto_checkt::add_guarded_claim(
   const exprt &src_expr,
   const guardt &guard)
 {
-  exprt simplified_expr(asserted_expr);
-
   // first try simplifier on it
-  if(enable_simplify)
-    simplify(simplified_expr, ns);
+  exprt simplified_expr =
+    enable_simplify ? simplify_expr(asserted_expr, ns) : asserted_expr;
 
   // throw away trivial properties?
   if(!retain_trivial && simplified_expr.is_true())
     return;
 
   // add the guard
-
-  exprt guarded_expr;
-
-  if(guard.is_true())
-    guarded_expr.swap(simplified_expr);
-  else
-    guarded_expr = implies_exprt(guard.as_expr(), std::move(simplified_expr));
+  exprt guarded_expr =
+    guard.is_true()
+      ? simplified_expr
+      : implies_exprt{guard.as_expr(), std::move(simplified_expr)};
 
   if(assertions.insert(guarded_expr).second)
   {