Optimize NewExpression visiting

- less enumerations
- less collections created

Author: alex-kulakov

Orm/Xtensive.Orm/Orm/Linq/Translator.Expressions.cs

@@ -690,17 +690,14 @@ protected override Expression VisitNew(NewExpression newExpression)
       // ReSharper restore ConditionIsAlwaysTrueOrFalse
       // ReSharper restore HeuristicUnreachableCode
 
-      IList<Expression> arguments = VisitNewExpressionArguments(newExpression);
-      if (arguments.Count == 0)
-        arguments = Array.Empty<Expression>();
+      var arguments = VisitNewExpressionArguments(newExpression, out var constructorParameters);
       if (newExpression.IsAnonymousConstructor()) {
         return newExpression.Members == null
           ? Expression.New(newExpression.Constructor, arguments)
           : Expression.New(newExpression.Constructor, arguments, newExpression.Members);
       }
 
-      var constructorParameters = newExpression.GetConstructorParameters();
-      if (constructorParameters.Length != arguments.Count)
+      if (constructorParameters.Length != arguments.Length)
         throw Exceptions.InternalError(Strings.ExInvalidNumberOfParametersInNewExpression, OrmLog.Instance);
 
       var bindings = GetBindingsForConstructor(constructorParameters, arguments, newExpression);

Orm/Xtensive.Orm/Orm/Linq/Translator.Materialization.cs

@@ -152,10 +152,15 @@ private Materializer
       return new Materializer(projectorExpression.CachingCompile());
     }
 
-    private List<Expression> VisitNewExpressionArguments(NewExpression n)
+    private Expression[] VisitNewExpressionArguments(NewExpression n, out ParameterInfo[] constructorParameters)
     {
-      var arguments = new List<Expression>();
+      constructorParameters = n.GetConstructorParameters();
+      if (n.Arguments.Count == 0) {
+        return Array.Empty<Expression>();
+      }
+      var arguments = new Expression[n.Arguments.Count];
       var origArguments = n.Arguments;
+
       for (int i = 0, count = origArguments.Count; i < count; i++) {
         var argument = origArguments[i];
 
@@ -169,16 +174,14 @@ private List<Expression> VisitNewExpressionArguments(NewExpression n)
         body = body.IsProjection()
           ? BuildSubqueryResult((ProjectionExpression) body, argument.Type)
           : ProcessProjectionElement(body);
-        arguments.Add(body);
-      }
-      var constructorParameters = n.GetConstructorParameters();
-      for (int i = 0; i < arguments.Count; i++) {
-        if (arguments[i].Type != constructorParameters[i].ParameterType)
-          arguments[i] = Expression.Convert(arguments[i], constructorParameters[i].ParameterType);
+        arguments[i] = body.Type != constructorParameters[i].ParameterType
+          ? Expression.Convert(body, constructorParameters[i].ParameterType)
+          : body;
       }
       return arguments;
     }
 
+
     private void VisitNewExpressionArgumentsSkipResults(NewExpression n)
     {
       var origArguments = n.Arguments;