[NativeAOT] Generate optimized type mapping

build-tools/create-packs/Microsoft.Android.Runtime.proj

@@ -44,6 +44,10 @@ projects that use the Microsoft.Android framework in .NET 6+.
           Include="$(_MonoAndroidNETOutputRoot)$(AndroidLatestStableApiLevel)\Microsoft.Android.Runtime.NativeAOT.dll"
           Condition=" '$(AndroidRuntime)' == 'NativeAOT' "
       />
+      <_AndroidRuntimePackAssemblies
+          Include="$(_MonoAndroidNETOutputRoot)$(AndroidLatestStableApiLevel)\System.IO.Hashing.dll"
+          Condition=" '$(AndroidRuntime)' == 'NativeAOT' "
+      />
       <_AndroidRuntimePackAssemblies Include="$(_MonoAndroidNETOutputRoot)$(AndroidLatestStableApiLevel)\Mono.Android.Export.dll" />
     </ItemGroup>
 

src/Microsoft.Android.Runtime.NativeAOT/Android.Runtime.NativeAOT/NativeAotTypeManager.cs

@@ -11,20 +11,8 @@ partial class NativeAotTypeManager : JniRuntime.JniTypeManager {
 	internal const DynamicallyAccessedMemberTypes Methods = DynamicallyAccessedMemberTypes.PublicMethods | DynamicallyAccessedMemberTypes.NonPublicMethods;
 	internal const DynamicallyAccessedMemberTypes MethodsAndPrivateNested = Methods | DynamicallyAccessedMemberTypes.NonPublicNestedTypes;
 
-	readonly IDictionary<string, Type> TypeMappings = new Dictionary<string, Type> (StringComparer.Ordinal);
-
 	public NativeAotTypeManager ()
 	{
-		var startTicks  = global::System.Environment.TickCount;
-		InitializeTypeMappings ();
-		var endTicks    = global::System.Environment.TickCount;
-		AndroidLog.Print (AndroidLogLevel.Info, "NativeAotTypeManager", $"InitializeTypeMappings() took {endTicks - startTicks}ms");
-	}
-
-	void InitializeTypeMappings ()
-	{
-		// Should be replaced by src/Microsoft.Android.Sdk.ILLink/TypeMappingStep.cs
-		throw new InvalidOperationException ("TypeMappings should be replaced during trimming!");
 	}
 
 	[return: DynamicallyAccessedMembers (Constructors)]
@@ -139,7 +127,7 @@ public override void RegisterNativeMembers (
 
 	protected override IEnumerable<Type> GetTypesForSimpleReference (string jniSimpleReference)
 	{
-		if (TypeMappings.TryGetValue (jniSimpleReference, out var target)) {
+		if (TypeMapping.TryGetType (jniSimpleReference, out var target)) {
 			yield return target;
 		}
 		foreach (var t in base.GetTypesForSimpleReference (jniSimpleReference)) {
@@ -150,15 +138,7 @@ protected override IEnumerable<Type> GetTypesForSimpleReference (string jniSimpl
 	protected override IEnumerable<string> GetSimpleReferences (Type type)
 	{
 		return base.GetSimpleReferences (type)
-			.Concat (CreateSimpleReferencesEnumerator (type));
-	}
-
-	IEnumerable<string> CreateSimpleReferencesEnumerator (Type type)
-	{
-		foreach (var e in TypeMappings) {
-			if (e.Value == type)
-				yield return e.Key;
-		}
+			.Concat (TypeMapping.GetJavaClassNames (type));
 	}
 
 	static int CountMethods (ReadOnlySpan<char> methodsSpan)

src/Microsoft.Android.Runtime.NativeAOT/Android.Runtime.NativeAOT/TypeMapping.cs

@@ -0,0 +1,59 @@
+using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
+using System.IO.Hashing;
+using System.Runtime.InteropServices;
+using System.Text;
+
+using Android.Runtime;
+
+namespace Microsoft.Android.Runtime;
+
+internal static class TypeMapping
+{
+	private static Dictionary<Type, string[]> s_javaClassNames = new ();
+
+	internal static bool TryGetType (string javaClassName, [NotNullWhen (true)] out Type? type)
+	{
+		ReadOnlySpan<byte> bytes = MemoryMarshal.AsBytes(javaClassName.AsSpan ());
+		ulong hash = XxHash3.HashToUInt64 (bytes);
+		type = GetType (hash);
+		return type is not null;
+	}
+
+	internal static IEnumerable<string> GetJavaClassNames (Type type)
+	{
+		if (!s_javaClassNames.TryGetValue (type, out var javaClassNames)) {
+			javaClassNames = GetJavaClassNamesSlow (type).ToArray ();
+			_ = s_javaClassNames.TryAdd (type, javaClassNames);
+		}
+
+		return javaClassNames;
+	}
+
+	private static IEnumerable<string> GetJavaClassNamesSlow (Type type)
+	{
+		for (int i = 0; i < Hashes.Length; i++) {
+			if (GetTypeByIndex (i) == type) {
+				var javaClassName = TypeMapping.GetJavaClassNameByIndex (i);
+				if (javaClassName is not null) {
+					yield return javaClassName;
+				}
+			}
+		}
+	}
+
+	private static Type? GetType (ulong hash)
+	{
+		int index = MemoryExtensions.BinarySearch (Hashes, hash);
+		if (index < 0) {
+			return null;
+		}
+
+		return GetTypeByIndex (index);
+	}
+
+	// Replaced by src/Microsoft.Android.Sdk.ILLink/TypeMappingStep.cs
+	private static ReadOnlySpan<ulong> Hashes => throw new NotImplementedException ();
+	private static Type? GetTypeByIndex (int index) => throw new NotImplementedException ();
+	private static string? GetJavaClassNameByIndex (int index) => throw new NotImplementedException ();
+}

src/Microsoft.Android.Runtime.NativeAOT/Microsoft.Android.Runtime.NativeAOT.csproj

@@ -21,6 +21,10 @@
     <ProjectReference Include="..\Mono.Android\Mono.Android.csproj" />
   </ItemGroup>
 
+  <ItemGroup>
+    <PackageReference Include="System.IO.Hashing" Version="$(SystemIOHashingPackageVersion)" />
+  </ItemGroup>
+
   <Import Project="Sdk.targets" Sdk="Microsoft.NET.Sdk" />
 
   <!-- Copy runtime assemblies to bin/$(Configuration)/dotnet/packs folder -->
@@ -34,6 +38,7 @@
   <Target Name="_CopyToPackDirs">
     <ItemGroup>
       <_RuntimePackFiles Include="$(OutputPath)Microsoft.Android.Runtime.NativeAOT.dll" AndroidRID="%(AndroidAbiAndRuntimeFlavor.AndroidRID)" AndroidRuntime="%(AndroidAbiAndRuntimeFlavor.AndroidRuntime)" />
+      <_RuntimePackFiles Include="$(OutputPath)System.IO.Hashing.dll" AndroidRID="%(AndroidAbiAndRuntimeFlavor.AndroidRID)" AndroidRuntime="%(AndroidAbiAndRuntimeFlavor.AndroidRuntime)" />
     </ItemGroup>
     <Message Importance="high" Text="$(TargetPath) %(AndroidAbiAndRuntimeFlavor.AndroidRID)" />
     <Copy