Optimize IronPython.Compiler.Ast.Arg (#1169)

Author: BCSharp

Src/IronPython/Compiler/Ast/Arg.cs

@@ -8,33 +8,33 @@
 
 namespace IronPython.Compiler.Ast {
     public class Arg : Node {
+        private static readonly Argument _listTypeArgument = new(ArgumentType.List);
+        private static readonly Argument _dictTypeArgument = new(ArgumentType.Dictionary);
+
         public Arg(Expression expression) : this(null, expression) { }
 
         public Arg(string? name, Expression expression) {
             Name = name;
             Expression = expression;
+
+            ArgumentInfo = name switch {
+                null => Argument.Simple,
+                "*"  => _listTypeArgument,
+                "**" => _dictTypeArgument,
+                _    => new Argument(name)
+            };
         }
 
         public string? Name { get; }
 
         public Expression Expression { get; }
 
+        internal Argument ArgumentInfo { get; }
+
         public override string ToString() {
             return base.ToString() + ":" + Name;
         }
 
-        internal Argument GetArgumentInfo() {
-            if (Name == null) {
-                return Argument.Simple;
-            } else if (Name == "*") {
-                return new Argument(ArgumentType.List);
-            } else if (Name == "**") {
-                return new Argument(ArgumentType.Dictionary);
-            } else {
-                return new Argument(Name);
-            }
-        }
-
         public override void Walk(PythonWalker walker) {
             if (walker.Walk(this)) {
                 Expression?.Walk(walker);

Src/IronPython/Compiler/Ast/CallExpression.cs

@@ -77,8 +77,8 @@ public override MSAst.Expression Reduce() {
             if (firstListPos > 0) {
                 foreach (var arg in args) {
                     if (i == firstListPos) break;
-                    Debug.Assert(arg.GetArgumentInfo().Kind == ArgumentType.Simple);
-                    kinds[i] = arg.GetArgumentInfo();
+                    Debug.Assert(arg.ArgumentInfo.Kind == ArgumentType.Simple);
+                    kinds[i] = arg.ArgumentInfo;
                     values[i + 2] = arg.Expression;
                     i++;
                 }
@@ -87,16 +87,16 @@ public override MSAst.Expression Reduce() {
             // unpack list arguments
             if (numList > 0) {
                 var arg = args[firstListPos];
-                Debug.Assert(arg.GetArgumentInfo().Kind == ArgumentType.List);
-                kinds[i] = arg.GetArgumentInfo();
+                Debug.Assert(arg.ArgumentInfo.Kind == ArgumentType.List);
+                kinds[i] = arg.ArgumentInfo;
                 values[i + 2] = UnpackListHelper(args, firstListPos);
                 i++;
             }
 
             // add named arguments
             if (Kwargs.Count != numDict) {
                 foreach (var arg in Kwargs) {
-                    var info = arg.GetArgumentInfo();
+                    var info = arg.ArgumentInfo;
                     if (info.Kind == ArgumentType.Named) {
                         kinds[i] = info;
                         values[i + 2] = arg.Expression;
@@ -108,8 +108,8 @@ public override MSAst.Expression Reduce() {
             // unpack dict arguments
             if (numDict > 0) {
                 var arg = Kwargs[firstDictPos];
-                Debug.Assert(arg.GetArgumentInfo().Kind == ArgumentType.Dictionary);
-                kinds[i] = arg.GetArgumentInfo();
+                Debug.Assert(arg.ArgumentInfo.Kind == ArgumentType.Dictionary);
+                kinds[i] = arg.ArgumentInfo;
                 values[i + 2] = UnpackDictHelper(Parent.LocalContext, Kwargs, numDict, firstDictPos);
             }
 
@@ -126,7 +126,7 @@ static void ScanArgs(IReadOnlyList<Arg> args, ArgumentType scanForType, out int
 
                 for (var i = args.Count - 1; i >= 0; i--) {
                     var arg = args[i];
-                    var info = arg.GetArgumentInfo();
+                    var info = arg.ArgumentInfo;
                     if (info.Kind == scanForType) {
                         firstArgPos = i;
                         numArgs++;
@@ -136,7 +136,7 @@ static void ScanArgs(IReadOnlyList<Arg> args, ArgumentType scanForType, out int
 
             static MSAst.Expression UnpackListHelper(IReadOnlyList<Arg> args, int firstListPos) {
                 Debug.Assert(args.Count > 0);
-                Debug.Assert(args[firstListPos].GetArgumentInfo().Kind == ArgumentType.List);
+                Debug.Assert(args[firstListPos].ArgumentInfo.Kind == ArgumentType.List);
 
                 if (args.Count - firstListPos == 1) return args[firstListPos].Expression;
 
@@ -145,7 +145,7 @@ static MSAst.Expression UnpackListHelper(IReadOnlyList<Arg> args, int firstListP
                 expressions.Add(Expression.Assign(varExpr, Expression.Call(AstMethods.MakeEmptyList)));
                 for (int i = firstListPos; i < args.Count; i++) {
                     var arg = args[i];
-                    if (arg.GetArgumentInfo().Kind == ArgumentType.List) {
+                    if (arg.ArgumentInfo.Kind == ArgumentType.List) {
                         expressions.Add(Expression.Call(AstMethods.ListExtend, varExpr, AstUtils.Convert(arg.Expression, typeof(object))));
                     } else {
                         expressions.Add(Expression.Call(AstMethods.ListAppend, varExpr, AstUtils.Convert(arg.Expression, typeof(object))));
@@ -158,7 +158,7 @@ static MSAst.Expression UnpackListHelper(IReadOnlyList<Arg> args, int firstListP
             static MSAst.Expression UnpackDictHelper(MSAst.Expression context, IReadOnlyList<Arg> kwargs, int numDict, int firstDictPos) {
                 Debug.Assert(kwargs.Count > 0);
                 Debug.Assert(0 < numDict && numDict <= kwargs.Count);
-                Debug.Assert(kwargs[firstDictPos].GetArgumentInfo().Kind == ArgumentType.Dictionary);
+                Debug.Assert(kwargs[firstDictPos].ArgumentInfo.Kind == ArgumentType.Dictionary);
 
                 if (numDict == 1) return kwargs[firstDictPos].Expression;
 
@@ -167,7 +167,7 @@ static MSAst.Expression UnpackDictHelper(MSAst.Expression context, IReadOnlyList
                 expressions.Add(Expression.Assign(varExpr, Expression.Call(AstMethods.MakeEmptyDict)));
                 for (int i = firstDictPos; i < kwargs.Count; i++) {
                     var arg = kwargs[i];
-                    if (arg.GetArgumentInfo().Kind == ArgumentType.Dictionary) {
+                    if (arg.ArgumentInfo.Kind == ArgumentType.Dictionary) {
                         expressions.Add(Expression.Call(AstMethods.DictMerge, context, varExpr, arg.Expression));
                     }
                 }
@@ -190,7 +190,7 @@ void IInstructionProvider.AddInstructions(LightCompiler compiler) {
             }
 
             for (int i = 0; i < args.Count; i++) {
-                if (!args[i].GetArgumentInfo().IsSimple) {
+                if (!args[i].ArgumentInfo.IsSimple) {
                     compiler.Compile(Reduce());
                     return;
                 }

Src/IronPython/Compiler/Parser.cs

@@ -1013,7 +1013,7 @@ private ClassDefinition ParseClassDef() {
             var keywords = new List<Arg>();
             if (MaybeEat(TokenKind.LeftParenthesis)) {
                 foreach (var arg in FinishArgumentList(null)) {
-                    var info = arg.GetArgumentInfo();
+                    var info = arg.ArgumentInfo;
                     if (info.Kind == Microsoft.Scripting.Actions.ArgumentType.Simple) {
                         bases.Add(arg.Expression);
                     } else if (info.Kind == Microsoft.Scripting.Actions.ArgumentType.Named) {