ILLink: Add EventDefinitionNode to dependency analysis

src/tools/illink/src/linker/Linker.Steps/DependencyNodes/EventDefinitionNode.cs

@@ -0,0 +1,42 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System.Collections.Generic;
+using ILCompiler.DependencyAnalysisFramework;
+using Mono.Cecil;
+
+namespace Mono.Linker.Steps
+{
+	public partial class MarkStep
+	{
+		internal sealed class EventDefinitionNode : DependencyNodeCore<NodeFactory>
+		{
+			EventDefinition _event;
+			public EventDefinitionNode (EventDefinition @event) => _event = @event;
+
+			public override bool InterestingForDynamicDependencyAnalysis => false;
+
+			public override bool HasDynamicDependencies => false;
+
+			public override bool HasConditionalStaticDependencies => false;
+
+			public override bool StaticDependenciesAreComputed => true;
+
+			public override IEnumerable<CombinedDependencyListEntry>? GetConditionalStaticDependencies (NodeFactory context) => null;
+
+			public override IEnumerable<DependencyListEntry>? GetStaticDependencies (NodeFactory context)
+			{
+				var eventOrigin = new MessageOrigin (_event);
+				context.MarkStep.MarkCustomAttributes (_event, new DependencyInfo (DependencyKind.CustomAttribute, _event), eventOrigin);
+				context.MarkStep.DoAdditionalEventProcessing (_event);
+				context.MarkStep.Annotations.MarkProcessed (_event);
+
+				return null;
+			}
+
+			public override IEnumerable<CombinedDependencyListEntry>? SearchDynamicDependencies (List<DependencyNodeCore<NodeFactory>> markedNodes, int firstNode, NodeFactory context) => null;
+
+			protected override string GetName (NodeFactory context) => _event.GetDisplayName ();
+		}
+	}
+}

src/tools/illink/src/linker/Linker.Steps/MarkStep.NodeFactory.cs

@@ -15,6 +15,7 @@ internal sealed class NodeFactory (MarkStep markStep)
 			public MarkStep MarkStep { get; } = markStep;
 			readonly NodeCache<TypeDefinition, TypeDefinitionNode> _typeNodes = new (static t => new TypeDefinitionNode(t));
 			readonly NodeCache<MethodDefinition, MethodDefinitionNode> _methodNodes = new (static _ => throw new InvalidOperationException ("Creation of node requires more than the key."));
+			readonly NodeCache<EventDefinition, EventDefinitionNode> _eventNodes = new (static e => new EventDefinitionNode (e));
 			readonly NodeCache<PropertyDefinition, PropertyDefinitionNode> _propertyNodes = new (static p => new PropertyDefinitionNode(p));
 			readonly NodeCache<TypeDefinition, TypeIsRelevantToVariantCastingNode> _typeIsRelevantToVariantCastingNodes = new (static (t) => new TypeIsRelevantToVariantCastingNode (t));
 
@@ -33,6 +34,11 @@ internal TypeIsRelevantToVariantCastingNode GetTypeIsRelevantToVariantCastingNod
 				return _typeIsRelevantToVariantCastingNodes.GetOrAdd (type);
 			}
 
+			internal EventDefinitionNode GetEventDefinitionNode (EventDefinition evt)
+			{
+				return _eventNodes.GetOrAdd (evt);
+			}
+
 			internal PropertyDefinitionNode GetPropertyNode (PropertyDefinition prop)
 			{
 				return _propertyNodes.GetOrAdd (prop);

src/tools/illink/src/linker/Linker.Steps/MarkStep.cs

@@ -3517,12 +3517,8 @@ protected internal virtual void MarkEvent (EventDefinition evt, in DependencyInf
 			MarkMethodIfNotNull (evt.InvokeMethod, new DependencyInfo (dependencyKind, evt), origin);
 			MarkMethodIfNotNull (evt.RemoveMethod, new DependencyInfo (dependencyKind, evt), origin);
 
-			if (!Annotations.MarkProcessed (evt, reason))
-				return;
-
-			var eventOrigin = new MessageOrigin (evt);
-			MarkCustomAttributes (evt, new DependencyInfo (DependencyKind.CustomAttribute, evt), eventOrigin);
-			DoAdditionalEventProcessing (evt);
+			Tracer.AddDirectDependency (evt, reason, true);
+			_dependencyGraph.AddRoot (_nodeFactory.GetEventDefinitionNode (evt), Enum.GetName (reason.Kind));
 		}
 
 		internal void MarkMethodIfNotNull (MethodReference method, in DependencyInfo reason, in MessageOrigin origin)

src/tools/illink/src/linker/Linker/Annotations.cs

@@ -280,6 +280,12 @@ public bool MarkProcessed (IMetadataTokenProvider provider, in DependencyInfo re
 			return processed.Add (provider);
 		}
 
+		internal bool MarkProcessed (IMetadataTokenProvider provider)
+		{
+			marked_pending.Remove (provider);
+			return processed.Add (provider);
+		}
+
 		public TypeDefinition[] GetPendingPreserve ()
 		{
 			return pending_preserve.ToArray ();