[X] generate less IL for x:Array (#21615)

- fixes #20745
dotnet · May 20, 2024 · db7a6ff · db7a6ff
1 parent 60a46c5
commit db7a6ff
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Showing 4 changed files with 65 additions and 33 deletions.
diff --git a/src/Controls/src/Build.Tasks/CompiledMarkupExtensions/ArrayExtension.cs b/src/Controls/src/Build.Tasks/CompiledMarkupExtensions/ArrayExtension.cs
@@ -26,7 +26,17 @@ IEnumerable<Instruction> ProvideValue(TypeReference typeTypeRef, IReadOnlyList<I
 
 			for (var i = 0; i < n; i++)
 			{
-				var vardef = context.Variables[items[i] as IElementNode];
+				var node = items[i] as IElementNode;
+				var vardef = context.Variables[node];
+				var vardefref = new VariableDefinitionReference(vardef);
+				context.IL.Append(SetPropertiesVisitor.ProvideValue(vardefref, context, module, node as ElementNode));
+				if (vardef != vardefref.VariableDefinition)
+				{
+					vardef = vardefref.VariableDefinition;
+					context.Body.Variables.Add(vardef);
+					context.Variables[node] = vardef;
+				}
+
 				if (typeTypeRef.IsValueType)
 				{
 					yield return Instruction.Create(OpCodes.Dup);

diff --git a/src/Controls/src/Build.Tasks/CreateObjectVisitor.cs b/src/Controls/src/Build.Tasks/CreateObjectVisitor.cs
@@ -51,6 +51,38 @@ public void Visit(ElementNode node, INode parentNode)
 			var typeref = Module.ImportReference(node.XmlType.GetTypeReference(Context.Cache, Module, node));
 			TypeDefinition typedef = typeref.ResolveCached(Context.Cache);
 
+			if (typeref.FullName == "Microsoft.Maui.Controls.Xaml.ArrayExtension")
+			{
+				var visitor = new SetPropertiesVisitor(Context);
+				var children = node.Properties.Values.ToList();
+				children.AddRange(node.CollectionItems);
+				foreach (var cnode in children)
+				{
+					if (cnode is not IElementNode en)
+						continue;
+					foreach (var n in en.Properties.Values.ToList())
+						n.Accept(visitor, cnode);
+					foreach (var n in en.CollectionItems)
+						n.Accept(visitor, cnode);
+				}
+
+				var il = new ArrayExtension().ProvideValue(node, Module, Context, out typeref);
+				var vardef = new VariableDefinition(typeref);
+				Context.Variables[node] = vardef;
+				Context.Body.Variables.Add(vardef);
+
+				Context.IL.Append(il);
+				Context.IL.Emit(OpCodes.Stloc, vardef);
+
+				//clean the node as it has been fully exhausted
+				foreach (var prop in node.Properties)
+					if (!node.SkipProperties.Contains(prop.Key))
+						node.SkipProperties.Add(prop.Key);
+				node.CollectionItems.Clear();
+
+				return;
+			}
+
 			if (IsXaml2009LanguagePrimitive(node))
 			{
 				var vardef = new VariableDefinition(typeref);
@@ -216,34 +248,6 @@ public void Visit(ElementNode node, INode parentNode)
 					Context.IL.Emit(OpCodes.Ldloca, vardef);
 					Context.IL.Emit(OpCodes.Initobj, Module.ImportReference(typedef));
 				}
-
-				if (typeref.FullName == "Microsoft.Maui.Controls.Xaml.ArrayExtension")
-				{
-					var visitor = new SetPropertiesVisitor(Context);
-					foreach (var cnode in node.Properties.Values.ToList())
-						cnode.Accept(visitor, node);
-					foreach (var cnode in node.CollectionItems)
-						cnode.Accept(visitor, node);
-
-					markupProvider = new ArrayExtension();
-
-					var il = markupProvider.ProvideValue(node, Module, Context, out typeref);
-
-					vardef = new VariableDefinition(typeref);
-					Context.Variables[node] = vardef;
-					Context.Body.Variables.Add(vardef);
-
-					Context.IL.Append(il);
-					Context.IL.Emit(OpCodes.Stloc, vardef);
-
-					//clean the node as it has been fully exhausted
-					foreach (var prop in node.Properties)
-						if (!node.SkipProperties.Contains(prop.Key))
-							node.SkipProperties.Add(prop.Key);
-					node.CollectionItems.Clear();
-
-					return;
-				}
 			}
 		}
 

diff --git a/src/Controls/tests/Xaml.UnitTests/XArray.xaml b/src/Controls/tests/Xaml.UnitTests/XArray.xaml
@@ -5,7 +5,7 @@
 	xmlns:sys="clr-namespace:System;assembly=mscorlib"
 	xmlns:local="clr-namespace:Microsoft.Maui.Controls.Xaml.UnitTests;assembly=Microsoft.Maui.Controls.Xaml.UnitTests"
 	x:Class="Microsoft.Maui.Controls.Xaml.UnitTests.XArray">
-	<x:Array Type="{x:Type sys:String}" x:Key="array">
+	<x:Array Type="{x:Type sys:String}" >
 		<x:String>Hello</x:String>
 		<x:String>World</x:String>
 	</x:Array>

diff --git a/src/Controls/tests/Xaml.UnitTests/XArray.xaml.cs b/src/Controls/tests/Xaml.UnitTests/XArray.xaml.cs
@@ -1,6 +1,6 @@
-using System;
-using System.Collections.Generic;
-using Microsoft.Maui.Controls;
+using System.Linq;
+using Mono.Cecil;
+using Mono.Cecil.Cil;
 using NUnit.Framework;
 
 namespace Microsoft.Maui.Controls.Xaml.UnitTests
@@ -38,6 +38,24 @@ public void SupportsXArray(bool useCompiledXaml)
 				Assert.AreEqual("Hello", ((string[])layout.Content)[0]);
 				Assert.AreEqual("World", ((string[])layout.Content)[1]);
 			}
+
+			[Test]
+			public void ArrayExtensionNotPresentInGeneratedCode([Values(false)] bool useCompiledXaml)
+			{
+				MockCompiler.Compile(typeof(XArray), out var methodDef);
+				Assert.That(!methodDef.Body.Instructions.Any(instr => InstructionIsArrayExtensionCtor(methodDef, instr)), "This Xaml still generates a new ArrayExtension()");
+			}
+
+			bool InstructionIsArrayExtensionCtor(MethodDefinition methodDef, Mono.Cecil.Cil.Instruction instruction)
+			{
+				if (instruction.OpCode != OpCodes.Newobj)
+					return false;
+				if (instruction.Operand is not MethodReference methodRef)
+					return false;
+				if (!Build.Tasks.TypeRefComparer.Default.Equals(methodRef.DeclaringType, methodDef.Module.ImportReference(typeof(ArrayExtension))))
+					return false;
+				return true;
+			}
 		}
 	}
 }