perf: Improve DependencyProperty propagation

- Remove linq usage in GetChildrenDependencyObjects
- Use HashTableEx in dependency property inheritance propagation to avoid JIT costs and improve lookup performance.

src/Uno.UI/UI/Xaml/DependencyObjectStore.AncestorsDictionary.cs

@@ -0,0 +1,54 @@
+#nullable enable
+
+using System;
+using Uno.UI.DataBinding;
+using System.Collections.Generic;
+using Uno.Extensions;
+using Uno.Logging;
+using Uno.Diagnostics.Eventing;
+using Uno.Disposables;
+using System.Linq;
+using System.Threading;
+using Uno.Collections;
+using System.Runtime.CompilerServices;
+using System.Diagnostics;
+using Windows.UI.Xaml.Data;
+using Uno.UI;
+using System.Collections;
+
+#if XAMARIN_ANDROID
+using View = Android.Views.View;
+#elif XAMARIN_IOS_UNIFIED
+using View = UIKit.UIView;
+#elif XAMARIN_IOS
+using View = MonoTouch.UIKit.UIView;
+#endif
+
+namespace Windows.UI.Xaml
+{
+	public partial class DependencyObjectStore : IDisposable
+	{
+		private class AncestorsDictionary
+		{
+			private readonly HashtableEx _entries = new HashtableEx();
+
+			internal bool TryGetValue(object key, out bool isAncestor)
+			{
+				if (_entries.TryGetValue(key, out var value))
+				{
+					isAncestor = (bool)value!;
+					return true;
+				}
+
+				isAncestor = false;
+				return false;
+			}
+
+			internal void Set(object key, bool isAncestor)
+				=> _entries[key] = isAncestor;
+
+			internal void Clear()
+				=> _entries.Clear();
+		}
+	}
+}

src/Uno.UI/UI/Xaml/DependencyObjectStore.cs

@@ -1183,11 +1183,17 @@ private void UpdateChildResourceBindings(bool isThemeChangedUpdate)
 		/// </remarks>
 		private IEnumerable<DependencyObject> GetChildrenDependencyObjects()
 		{
-			var propertyValues = _properties.GetAllDetails()
-				.Except(_properties.DataContextPropertyDetails, _properties.TemplatedParentPropertyDetails)
-				.Select(d => GetValue(d));
-			foreach (var propertyValue in propertyValues)
+			foreach (var propertyDetail in _properties.GetAllDetails())
 			{
+				if(propertyDetail == null
+					|| propertyDetail == _properties.DataContextPropertyDetails
+					|| propertyDetail == _properties.TemplatedParentPropertyDetails)
+				{
+					continue;
+				}
+
+				var propertyValue = GetValue(propertyDetail);
+
 				if (propertyValue is IEnumerable<DependencyObject> dependencyObjectCollection &&
 					// Try to avoid enumerating collections that shouldn't be enumerated, since we may be encountering user-defined values. This may need to be refined to somehow only consider values coming from the framework itself.
 					(propertyValue is ICollection || propertyValue is DependencyObjectCollectionBase)
@@ -1326,7 +1332,7 @@ private void PropagateInheritedNonLocalProperties(DependencyObjectStore? childSt
 			// properties.
 
 			// Ancestors is a local cache to avoid walking up the tree multiple times.
-			var ancestors = new Dictionary<object, bool>();
+			var ancestors = new AncestorsDictionary();
 
 			// This alias is used to avoid the resolution of the underlying WeakReference during the
 			// call to IsAncestor.
@@ -1374,7 +1380,7 @@ void Propagate(DependencyObjectStore store)
 			}
 		}
 
-		private static bool IsAncestor(DependencyObject? instance, Dictionary<object, bool> map, object ancestor)
+		private static bool IsAncestor(DependencyObject? instance, AncestorsDictionary map, object ancestor)
 		{
 #if DEBUG
 			var hashSet = new HashSet<DependencyObject>(Uno.ReferenceEqualityComparer<DependencyObject>.Default);
@@ -1417,7 +1423,7 @@ private static bool IsAncestor(DependencyObject? instance, Dictionary<object, bo
 
 				}
 
-				map[ancestor] = isAncestor;
+				map.Set(ancestor, isAncestor);
 			}
 
 			return isAncestor;

src/Uno.UI/UI/Xaml/DependencyPropertyDetailsCollection.cs

@@ -22,7 +22,7 @@ namespace Windows.UI.Xaml
 	/// </remarks>
 	partial class DependencyPropertyDetailsCollection : IDisposable
 	{
-		private static readonly DependencyPropertyDetails[] Empty = new DependencyPropertyDetails[0];
+		private static readonly DependencyPropertyDetails?[] Empty = new DependencyPropertyDetails?[0];
 
 		private readonly Type _ownerType;
 		private readonly ManagedWeakReference _ownerReference;
@@ -33,9 +33,9 @@ partial class DependencyPropertyDetailsCollection : IDisposable
 		private DependencyPropertyDetails? _dataContextPropertyDetails;
 		private DependencyPropertyDetails? _templatedParentPropertyDetails;
 
-		private readonly static ArrayPool<DependencyPropertyDetails> _pool = ArrayPool<DependencyPropertyDetails>.Create(500, 100);
+		private readonly static ArrayPool<DependencyPropertyDetails?> _pool = ArrayPool<DependencyPropertyDetails?>.Create(500, 100);
 
-		private DependencyPropertyDetails[]? _entries;
+		private DependencyPropertyDetails?[]? _entries;
 		private int _entriesLength;
 		private int _minId;
 		private int _maxId;
@@ -56,7 +56,7 @@ public DependencyPropertyDetailsCollection(Type ownerType, ManagedWeakReference
 			_templatedParentProperty = templatedParentProperty;
 		}
 
-		private DependencyPropertyDetails[] Entries
+		private DependencyPropertyDetails?[] Entries
 		{
 			get
 			{
@@ -154,7 +154,7 @@ public DependencyPropertyDetails FindPropertyDetails(DependencyProperty property
 				if (forceCreate)
 				{
 					int newEntriesSize;
-					DependencyPropertyDetails[] newEntries;
+					DependencyPropertyDetails?[] newEntries;
 
 					if (entryIndex < 0)
 					{
@@ -210,7 +210,7 @@ private bool TryResolveDefaultValueFromProviders(DependencyProperty property, ou
 			return false;
 		}
 
-		private void AssignEntries(DependencyPropertyDetails[] newEntries, int newSize)
+		private void AssignEntries(DependencyPropertyDetails?[] newEntries, int newSize)
 		{
 			ReturnEntriesToPool();
 
@@ -230,7 +230,7 @@ private void ReturnEntriesToPool()
 			}
 		}
 
-		internal IEnumerable<DependencyPropertyDetails> GetAllDetails() => Entries.Trim();
+		internal DependencyPropertyDetails?[] GetAllDetails() => Entries;
 
 		/// <summary>
 		/// Adds a default value provider.