[Xamarin.Android.Build.Tasks] Profiled AOT can Full AOT the main assembly (#6482)

jonathanpeppers · web-flow · commit 8ac442519063 · 2021-11-16T08:28:00.000-06:00
When using the built-in profiles for Profiled AOT, one drawback is
the user's code isn't AOT'd.  We only AOT types that are called in
the BCL, `Java.Interop.dll`, `Mono.Android.dll`, etc.

To make this better, we can AOT the "main" assembly.  Most code in
the users' main assembly would likely get called on startup.  This
should have a minor impact to `.apk` size, but gain us a better
startup boost by default.

When testing, I can see more methods AOT'd:

	11-11 09:01:01.441 16386 16386 D Mono    : AOT: FOUND method foo.MainActivity:OnCreate (Android.OS.Bundle) [0x7c050e8e20f0 - 0x7c050e8e213b 0x7c050e8e2673]

~~ Results ~~

| Test                                  |     File Size (Δ) |    Activity Displayed (Δ) |
| ------------------------------------- | ----------------: | ------------------------: |
|      `dotnet new android` w/o AOT app |        -baseline- |                     193ms |
|   `dotnet new android` *with* AOT app |              (0%) |               192ms (99%) |
|         `dotnet new maui` w/o AOT app |        -baseline- |                     641ms | 
|      `dotnet new maui` *with* AOT app |   +20,480 (0.14%) |               627ms (98%) |

The `dotnet new android` app is built with:

	&gt; dotnet build -c Release -p:AndroidEnableProfiledAot=true -p:RunAOTCompilation=true -r android-arm64 -p:AndroidPackageFormat=apk

File size differences:

	&gt; apkdiff -f before.apk after.apk
	Size difference in bytes ([*1] apk1 only, [*2] apk2 only):
	+       5,632 lib/arm64-v8a/libaot-foo.dll.so
	+           5 assemblies/assemblies.blob
	Summary:
	+           5 Other entries 0.00% (of 787,048)
	+           0 Dalvik executables 0.00% (of 345,340)
	+       5,632 Shared libraries 0.09% (of 6,008,168)
	+           0 Package size difference 0.00% (of 3,169,571)

10 runs on a Pixel 5 was an average of 193ms before, and 192ms after
(the `Activity Displayed` time).  There may not, in fact, be a
difference for `dotnet new android`.

Next I installed .NET MAUI 6.0.101-preview.11.2149, and tried a
`dotnet new maui` app:

File size:

	&gt; apkdiff -f before.apk after.apk
	Size difference in bytes ([*1] apk1 only, [*2] apk2 only):
	+      67,144 lib/arm64-v8a/libaot-foo.dll.so
	Summary:
	+           0 Other entries 0.00% (of 7,765,174)
	+           0 Dalvik executables 0.00% (of 6,443,152)
	+      67,144 Shared libraries 0.50% (of 13,388,688)
	+      20,480 Package size difference 0.14% (of 14,272,332)

Total file size difference:

	--14,251,852
	++14,272,332

The average over 10 runs on a Pixel 5, before applying this change,
is ~641ms.  After applying this change, it's ~627ms.

I think this might help startup by ~14ms in a `dotnet new maui` app.
It would likely improve more depending on the app.
diff --git a/src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.Aot.targets b/src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.Aot.targets
@@ -30,7 +30,7 @@ They run in a context of an inner build with a single $(RuntimeIdentifier).
     <Import Project="Sdk.props" Sdk="Microsoft.NETCore.App.Runtime.AOT.Cross.android-arm64" />
   </ImportGroup>
 
-  <UsingTask TaskName="Xamarin.Android.Tasks.GetAotArguments" AssemblyFile="$(_XamarinAndroidBuildTasksAssembly)" />
+  <UsingTask TaskName="Xamarin.Android.Tasks.GetAotAssemblies" AssemblyFile="$(_XamarinAndroidBuildTasksAssembly)" />
 
   <Target Name="_AndroidAotInputs">
     <ItemGroup>
@@ -43,39 +43,34 @@ They run in a context of an inner build with a single $(RuntimeIdentifier).
       DependsOnTargets="_AndroidAotInputs"
       Inputs="@(_AndroidAotInputs)"
       Outputs="$(_AndroidStampDirectory)_AndroidAot.stamp">
-    <GetAotArguments
+    <ItemGroup>
+      <AndroidAotProfile Include="$(MSBuildThisFileDirectory)dotnet.aotprofile" Condition=" '$(AndroidEnableProfiledAot)' == 'true' and '$(AndroidUseDefaultAotProfile)' != 'false' " />
+    </ItemGroup>
+    <GetAotAssemblies
         AndroidAotMode="$(AndroidAotMode)"
         AndroidNdkDirectory="$(_AndroidNdkDirectory)"
         AndroidBinUtilsDirectory="$(AndroidBinUtilsDirectory)"
         AndroidApiLevel="$(_AndroidApiLevel)"
         MinimumSupportedApiLevel="$(AndroidMinimumSupportedApiLevel)"
         AndroidSequencePointsMode="$(_SequencePointsMode)"
         AotAdditionalArguments="$(AndroidAotAdditionalArguments)"
+        TargetName="$(TargetName)"
+        ResolvedAssemblies="@(_AndroidAotInputs)"
         AotOutputDirectory="$(_AndroidAotBinDirectory)"
         RuntimeIdentifier="$(RuntimeIdentifier)"
         EnableLLVM="$(EnableLLVM)"
         UsingAndroidNETSdk="true"
-        Profiles="@(_AotProfiles)">
-      <Output PropertyName="_AotArguments" TaskParameter="Arguments" />
-      <Output PropertyName="_AotOutputDirectory" TaskParameter="OutputDirectory" />
-    </GetAotArguments>
+        Profiles="@(AndroidAotProfile)">
+      <Output ItemName="_MonoAOTAssemblies" TaskParameter="ResolvedAssemblies" />
+    </GetAotAssemblies>
     <PropertyGroup>
       <_MonoAOTCompilerPath>@(MonoAotCrossCompiler->WithMetadataValue('RuntimeIdentifier', '$(RuntimeIdentifier)'))</_MonoAOTCompilerPath>
       <_LLVMPath Condition=" '$(EnableLLVM)' == 'true' ">$([System.IO.Path]::GetDirectoryName ('$(_MonoAOTCompilerPath)'))</_LLVMPath>
     </PropertyGroup>
-    <ItemGroup>
-      <_MonoAOTAssemblies
-          Include="@(_AndroidAotInputs->'%(FullPath)')"
-          TempDirectory="$([MSBuild]::EnsureTrailingSlash($(_AotOutputDirectory)))%(FileName)"
-          AotArguments="$(_AotArguments),temp-path=$([System.IO.Path]::GetFullPath(%(_MonoAOTAssemblies.TempDirectory)))"
-      />
-      <AndroidAotProfile Include="$(MSBuildThisFileDirectory)dotnet.aotprofile" Condition=" '$(AndroidEnableProfiledAot)' == 'true' and '$(AndroidUseDefaultAotProfile)' != 'false' " />
-    </ItemGroup>
-    <MakeDir Directories="$(IntermediateOutputPath)aot\;@(_MonoAOTAssemblies->'%(TempDirectory)')" />
+    <MakeDir Directories="$(IntermediateOutputPath)aot\" />
     <MonoAOTCompiler
-        Assemblies="@(_MonoAOTAssemblies)"
+        Assemblies="@(_MonoAOTAssemblies->'%(FullPath)')"
         CompilerBinaryPath="$(_MonoAOTCompilerPath)"
-        AotProfilePath="@(AndroidAotProfile->'%(FullPath)')"
         DisableParallelAot="$(_DisableParallelAot)"
         IntermediateOutputPath="$(IntermediateOutputPath)"
         LibraryFormat="So"
diff --git a/src/Xamarin.Android.Build.Tasks/Tasks/Aot.cs b/src/Xamarin.Android.Build.Tasks/Tasks/Aot.cs
@@ -32,9 +32,6 @@ public class Aot : GetAotArguments
 	{
 		public override string TaskPrefix => "AOT";
 
-		[Required]
-		public ITaskItem[] ResolvedAssemblies { get; set; }
-
 		// Which ABIs to include native libs for
 		[Required]
 		public string [] SupportedAbis { get; set; }
@@ -145,6 +142,17 @@ IEnumerable<Config> GetAotConfigs (NdkTools ndk)
 					aotOptions.Insert (0, $"outfile={outputFile}");
 					aotOptions.Insert (0, $"llvm-path={SdkBinDirectory}");
 					aotOptions.Insert (0, $"temp-path={tempDir}");
+					if (Profiles != null && Profiles.Length > 0) {
+						if (Path.GetFileNameWithoutExtension (assembly.ItemSpec) == TargetName) {
+							LogDebugMessage ($"Not using profile(s) for main assembly: {assembly.ItemSpec}");
+						} else {
+							aotOptions.Add ("profile-only");
+							foreach (var p in Profiles) {
+								var fp = Path.GetFullPath (p.ItemSpec);
+								aotOptions.Add ($"profile={fp}");
+							}
+						}
+					}
 
 					// we need to quote the entire --aot arguments here to make sure it is parsed
 					// on windows as one argument. Otherwise it will be split up into multiple
diff --git a/src/Xamarin.Android.Build.Tasks/Tasks/GetAotArguments.cs b/src/Xamarin.Android.Build.Tasks/Tasks/GetAotArguments.cs
@@ -2,7 +2,6 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
-using System.Threading.Tasks;
 using Java.Interop.Tools.Diagnostics;
 using Microsoft.Android.Build.Tasks;
 using Microsoft.Build.Framework;
@@ -12,12 +11,10 @@ namespace Xamarin.Android.Tasks
 {
 	/// <summary>
 	/// The <Aot/> task subclasses this in "legacy" Xamarin.Android.
-	/// Called directly in .NET 5 to populate %(AotArguments) metadata.
+	/// The <GetAotAssemblies/> task subclasses this in .NET 6+.
 	/// </summary>
-	public class GetAotArguments : AndroidAsyncTask
+	public abstract class GetAotArguments : AndroidAsyncTask
 	{
-		public override string TaskPrefix => "GAOT";
-
 		[Required]
 		public string AndroidApiLevel { get; set; }
 
@@ -30,6 +27,9 @@ public class GetAotArguments : AndroidAsyncTask
 		[Required]
 		public string AndroidBinUtilsDirectory { get; set; }
 
+		[Required]
+		public string TargetName { get; set; }
+
 		/// <summary>
 		/// Will be blank in .NET 6+
 		/// </summary>
@@ -54,11 +54,8 @@ public class GetAotArguments : AndroidAsyncTask
 
 		public string AotAdditionalArguments { get; set; }
 
-		[Output]
-		public string Arguments { get; set; }
-
-		[Output]
-		public string OutputDirectory { get; set; }
+		[Required, Output]
+		public ITaskItem [] ResolvedAssemblies { get; set; }
 
 		protected AotMode AotMode;
 		protected SequencePointsMode SequencePointsMode;
@@ -110,42 +107,6 @@ public static bool TryGetSequencePointsMode (string value, out SequencePointsMod
 			return false;
 		}
 
-		public override Task RunTaskAsync ()
-		{
-			NdkTools? ndk = NdkTools.Create (AndroidNdkDirectory, Log);
-			if (ndk == null) {
-				return Task.CompletedTask; // NdkTools.Create will log appropriate error
-			}
-
-			bool hasValidAotMode = GetAndroidAotMode (AndroidAotMode, out AotMode);
-			if (!hasValidAotMode) {
-				LogCodedError ("XA3002", Properties.Resources.XA3002, AndroidAotMode);
-				return Task.CompletedTask;
-			}
-
-			if (AotMode == AotMode.Interp) {
-				LogDebugMessage ("Interpreter AOT mode enabled");
-				return Task.CompletedTask;
-			}
-
-			TryGetSequencePointsMode (AndroidSequencePointsMode, out SequencePointsMode);
-
-			SdkBinDirectory = MonoAndroidHelper.GetOSBinPath ();
-
-			var abi = AndroidRidAbiHelper.RuntimeIdentifierToAbi (RuntimeIdentifier);
-			if (string.IsNullOrEmpty (abi)) {
-				Log.LogCodedError ("XA0035", Properties.Resources.XA0035, RuntimeIdentifier);
-				return Task.CompletedTask;
-			}
-
-			(_, string outdir, string mtriple, AndroidTargetArch arch) = GetAbiSettings (abi);
-			string toolPrefix = GetToolPrefix (ndk, arch, out int level);
-
-			Arguments = string.Join (",", GetAotOptions (ndk, arch, level, outdir, mtriple, toolPrefix));
-			OutputDirectory = outdir;
-			return Task.CompletedTask;
-		}
-
 		protected string GetToolPrefix (NdkTools ndk, AndroidTargetArch arch, out int level)
 		{
 			level = 0;
@@ -252,13 +213,6 @@ protected List<string> GetAotOptions (NdkTools ndk, AndroidTargetArch arch, int
 		{
 			List<string> aotOptions = new List<string> ();
 
-			if (Profiles != null && Profiles.Length > 0) {
-				aotOptions.Add ("profile-only");
-				foreach (var p in Profiles) {
-					var fp = Path.GetFullPath (p.ItemSpec);
-					aotOptions.Add ($"profile={fp}");
-				}
-			}
 			if (!string.IsNullOrEmpty (AotAdditionalArguments))
 				aotOptions.Add (AotAdditionalArguments);
 			if (SequencePointsMode == SequencePointsMode.Offline)
diff --git a/src/Xamarin.Android.Build.Tasks/Tasks/GetAotAssemblies.cs b/src/Xamarin.Android.Build.Tasks/Tasks/GetAotAssemblies.cs
@@ -0,0 +1,74 @@
+using System.IO;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.Android.Build.Tasks;
+using Xamarin.Android.Tools;
+
+namespace Xamarin.Android.Tasks
+{
+	/// <summary>
+	/// Called in .NET 6+ to populate %(AotArguments) metadata in the ResolvedAssemblies [Output] property.
+	/// </summary>
+	public class GetAotAssemblies : GetAotArguments
+	{
+		public override string TaskPrefix => "GAOT";
+
+		public override Task RunTaskAsync ()
+		{
+			NdkTools? ndk = NdkTools.Create (AndroidNdkDirectory, Log);
+			if (ndk == null) {
+				return Task.CompletedTask; // NdkTools.Create will log appropriate error
+			}
+
+			bool hasValidAotMode = GetAndroidAotMode (AndroidAotMode, out AotMode);
+			if (!hasValidAotMode) {
+				LogCodedError ("XA3002", Properties.Resources.XA3002, AndroidAotMode);
+				return Task.CompletedTask;
+			}
+
+			if (AotMode == AotMode.Interp) {
+				LogDebugMessage ("Interpreter AOT mode enabled");
+				return Task.CompletedTask;
+			}
+
+			TryGetSequencePointsMode (AndroidSequencePointsMode, out SequencePointsMode);
+
+			SdkBinDirectory = MonoAndroidHelper.GetOSBinPath ();
+
+			var abi = AndroidRidAbiHelper.RuntimeIdentifierToAbi (RuntimeIdentifier);
+			if (string.IsNullOrEmpty (abi)) {
+				Log.LogCodedError ("XA0035", Properties.Resources.XA0035, RuntimeIdentifier);
+				return Task.CompletedTask;
+			}
+
+			(_, string outdir, string mtriple, AndroidTargetArch arch) = GetAbiSettings (abi);
+			string toolPrefix = GetToolPrefix (ndk, arch, out int level);
+
+			var aotOptions = GetAotOptions (ndk, arch, level, outdir, mtriple, toolPrefix);
+
+			var aotProfiles = new StringBuilder ();
+			if (Profiles != null && Profiles.Length > 0) {
+				aotProfiles.Append (",profile-only");
+				foreach (var p in Profiles) {
+					var fp = Path.GetFullPath (p.ItemSpec);
+					aotProfiles.Append (",profile=");
+					aotProfiles.Append (fp);
+				}
+			}
+
+			var arguments = string.Join (",", aotOptions);
+			foreach (var assembly in ResolvedAssemblies) {
+				var temp = Path.GetFullPath (Path.Combine (outdir, Path.GetFileNameWithoutExtension (assembly.ItemSpec)));
+				Directory.CreateDirectory (temp);
+				if (Path.GetFileNameWithoutExtension (assembly.ItemSpec) == TargetName) {
+					LogDebugMessage ($"Not using profile(s) for main assembly: {assembly.ItemSpec}");
+					assembly.SetMetadata ("AotArguments", $"{arguments},temp-path={temp}");
+				} else {
+					assembly.SetMetadata ("AotArguments", $"{arguments},temp-path={temp}{aotProfiles}");
+				}
+			}
+
+			return Task.CompletedTask;
+		}
+	}
+}
diff --git a/src/Xamarin.Android.Build.Tasks/Xamarin.Android.Legacy.targets b/src/Xamarin.Android.Build.Tasks/Xamarin.Android.Legacy.targets
@@ -700,6 +700,7 @@ projects. .NET 5 projects will not import this file.
         AndroidSequencePointsMode="$(_SequencePointsMode)"
         AotAdditionalArguments="$(AndroidAotAdditionalArguments)"
         ExtraAotOptions="$(AndroidExtraAotOptions)"
+        TargetName="$(TargetName)"
         ResolvedAssemblies="@(_ShrunkAssemblies)"
         AotOutputDirectory="$(_AndroidAotBinDirectory)"
         IntermediateAssemblyDir="$(MonoAndroidIntermediateAssemblyDir)"
diff --git a/tests/apk-sizes-reference/Xamarin.Forms_Performance_Integration-Signed-Release-Profiled-Aot.apkdesc b/tests/apk-sizes-reference/Xamarin.Forms_Performance_Integration-Signed-Release-Profiled-Aot.apkdesc
@@ -245,7 +245,7 @@
       "Size": 13656
     },
     "lib/armeabi-v7a/libaot-Xamarin.Forms.Performance.Integration.Droid.dll.so": {
-      "Size": 10648
+      "Size": 260040
     },
     "lib/armeabi-v7a/libaot-Xamarin.Forms.Platform.Android.dll.so": {
       "Size": 1333820
@@ -389,7 +389,7 @@
       "Size": 21520
     },
     "lib/x86/libaot-Xamarin.Forms.Performance.Integration.Droid.dll.so": {
-      "Size": 14488
+      "Size": 178024
     },
     "lib/x86/libaot-Xamarin.Forms.Platform.Android.dll.so": {
       "Size": 1182700
@@ -2243,5 +2243,5 @@
       "Size": 347268
     }
   },
-  "PackageSize": 17233092
+  "PackageSize": 17417412
 }
