[msbuild] Add ILStrip'ing for net6 applications. Fixes #11445. (#12563)

- Controlled by EnableAssemblyILStripping which defaults to true - Integration test included Before - https://gist.github.com/chamons/c7886f7bacbc2e5ac5966e4251d13e71 After - https://gist.github.com/chamons/148e1bef22fa336f953f3d02dcf20667 859,136 -> 527,872 managed Fixes #11445.
xamarin · Oct 5, 2021 · a300dfc · a300dfc · vs-mobiletools-engineering-service2 · Oct 5, 2021
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Showing 13 changed files with 169 additions and 18 deletions.
diff --git a/dotnet/targets/Xamarin.Shared.Sdk.targets b/dotnet/targets/Xamarin.Shared.Sdk.targets
@@ -12,6 +12,7 @@
 	<UsingTask TaskName="Xamarin.MacDev.Tasks.LinkNativeCode" AssemblyFile="$(_XamarinTaskAssembly)" />
 	<UsingTask TaskName="Xamarin.MacDev.Tasks.SymbolStrip" AssemblyFile="$(_XamarinTaskAssembly)" />
 	<UsingTask TaskName="Xamarin.MacDev.Tasks.MergeAppBundles" AssemblyFile="$(_XamarinTaskAssembly)" />
+	<UsingTask TaskName="Xamarin.MacDev.Tasks.ILStrip" AssemblyFile="$(_XamarinTaskAssembly)" />
 
 	<!-- Project types and how do we distinguish between them
 
@@ -209,6 +210,7 @@
 		<!-- We re-use ComputeFilesToPublish & CopyFilesToPublishDirectory to copy files to the .app -->
 		<!-- ComputeFilesToPublish will run ILLink -->
 		<!-- single-rid build (either plain single, or inner build for multi-rid build) -->
+		<!-- Note - _ComputeStripAssemblyIL must be before _StripAssemblyIL as msbuild DependsOn do not execute before Conditions are evaluated -->
 		<CreateAppBundleDependsOn Condition="'$(RuntimeIdentifiers)' == ''">
 			$(CreateAppBundleDependsOn);
 			_CopyResourcesToBundle;
@@ -226,6 +228,8 @@
 			_ComputeFrameworkFilesToPublish;
 			_ComputeDynamicLibrariesToPublish;
 			ComputeFilesToPublish;
+			_ComputeStripAssemblyIL;
+			_StripAssemblyIL;
 			_LoadLinkerOutput;
 			_CompileNativeExecutable;
 			_LinkNativeExecutable;
@@ -628,6 +632,40 @@
 		</ItemGroup>
 	</Target>
 
+	<Target Name="_ComputeStripAssemblyIL" Condition=" '$(EnableAssemblyILStripping)' == '' " DependsOnTargets="_ComputeVariables;ComputeFilesToPublish">
+		<PropertyGroup>
+			<!-- Don't strip IL by default -->
+			<EnableAssemblyILStripping>false</EnableAssemblyILStripping>
+
+			<!-- Strip if we are AOT and Release  -->
+			<EnableAssemblyILStripping Condition="'$(_RunAotCompiler)' == 'true' And '$(Configuration)' == 'Release'">true</EnableAssemblyILStripping>
+
+			<!-- Don't strip if we are running the interpreter  -->
+			<EnableAssemblyILStripping Condition="'$(MtouchInterpreter)' != ''">false</EnableAssemblyILStripping>
+		</PropertyGroup>
+	</Target>
+
+	<!-- The DependsOnTargets here will not force EnableAssemblyILStripping to be calculated before the condition is evaulated. The order in CreateAppBundleDependsOn matters. -->
+	<Target Name="_StripAssemblyIL" Condition="'$(EnableAssemblyILStripping)' == 'true'" DependsOnTargets="_ComputeStripAssemblyIL">
+		<PropertyGroup>
+			<_StrippedAssemblyDirectory>$(DeviceSpecificIntermediateOutputPath)\stripped</_StrippedAssemblyDirectory>
+		</PropertyGroup>
+		<MakeDir SessionId="$(BuildSessionId)" Condition="'$(IsMacEnabled)' == 'true'" Directories="$(_StrippedAssemblyDirectory)" />
+		<ItemGroup>
+			<_AssembliesToBeStripped Include="@(ResolvedFileToPublish)" Condition="'%(Extension)' == '.dll'">
+				<OutputPath>$(_StrippedAssemblyDirectory)\%(Filename)%(Extension)</OutputPath>
+			</_AssembliesToBeStripped>
+		</ItemGroup>
+		<Xamarin.MacDev.Tasks.ILStrip Assemblies="@(_AssembliesToBeStripped)" SessionId="$(BuildSessionId)">
+			<Output TaskParameter="StrippedAssemblies" PropertyName="_StrippedAssemblies" />
+		</Xamarin.MacDev.Tasks.ILStrip>
+		<ItemGroup>
+			<ResolvedFileToPublish Remove="@(_AssembliesToBeStripped)" />
+			<ResolvedFileToPublish Include="@(_StrippedAssemblies)" />
+		</ItemGroup>
+	</Target>
+
+
 	<Target Name="_LoadLinkerOutput" DependsOnTargets="ComputeFilesToPublish">
 		<!-- Load _MainFile -->
 		<ReadItemsFromFile SessionId="$(BuildSessionId)" File="$(_LinkerItemsDirectory)/_MainFile.items" Condition="Exists('$(_LinkerItemsDirectory)/_MainFile.items')">

diff --git a/eng/Versions.props b/eng/Versions.props
@@ -4,5 +4,6 @@
     <MicrosoftDotnetSdkInternalPackageVersion>6.0.100-rtm.21480.21</MicrosoftDotnetSdkInternalPackageVersion>
     <MicrosoftNETILLinkTasksPackageVersion>6.0.100-1.21473.1</MicrosoftNETILLinkTasksPackageVersion>
     <MicrosoftDotNetBuildTasksFeedPackageVersion>6.0.0-beta.21212.6</MicrosoftDotNetBuildTasksFeedPackageVersion>
+    <MicrosoftNETILStripTasksPackageVersion>6.0.0-rc.2.21468.3</MicrosoftNETILStripTasksPackageVersion>
   </PropertyGroup>
 </Project>
diff --git a/msbuild/ILMerge.targets b/msbuild/ILMerge.targets
@@ -32,6 +32,7 @@
       <MergedAssemblies Include="@(ReferencePath)" Condition="'%(FileName)' == 'Xamarin.MacDev'" />
       <MergedAssemblies Include="@(ReferencePath)" Condition="'%(FileName)' == 'DotNetZip'" />
       <MergedAssemblies Include="@(ReferencePath)" Condition="'%(FileName)' == 'ILLink.Tasks'" />
+      <MergedAssemblies Include="@(ReferencePath)" Condition="'%(FileName)' == 'ILStrip'" />
       <MergedAssemblies Include="@(ReferencePath)" Condition="'%(FileName)' == 'Newtonsoft.Json'" />
       <MergedAssemblies Include="@(ReferencePath)" Condition="'%(FileName)' == 'Renci.SshNet'" />
       <MergedAssemblies Include="@(ReferencePath)" Condition="'%(FileName)' == 'SshNet.Security.Cryptography'" />

diff --git a/msbuild/Xamarin.MacDev.Tasks.Core/Tasks/ParseBundlerArgumentsTaskBase.cs b/msbuild/Xamarin.MacDev.Tasks.Core/Tasks/ParseBundlerArgumentsTaskBase.cs
@@ -35,6 +35,9 @@ public abstract class ParseBundlerArgumentsTaskBase : XamarinTask {
 		public string Registrar { get; set; }
 
 		// This is input too
+		[Output]
+		public string NoStrip { get; set; }
+
 		[Output]
 		public int Verbosity { get; set; }
 
@@ -142,6 +145,10 @@ public override bool Execute ()
 						value = hasValue ? value : nextValue; // requires a value, which might be the next option
 						xml.Add (value);
 						break;
+					case "nostrip":
+						// Output is EnableAssemblyILStripping so we enable if --nostrip=false and disable if true
+						NoStrip = ParseBool (value) ? "false" : "true";
+						break;
 					default:
 						Log.LogMessage (MessageImportance.Low, "Skipping unknown argument '{0}' with value '{1}'", name, value);
 						break;

diff --git a/msbuild/Xamarin.Shared/Xamarin.Shared.targets b/msbuild/Xamarin.Shared/Xamarin.Shared.targets
@@ -1647,6 +1647,7 @@ Copyright (C) 2018 Microsoft. All rights reserved.
 			<Output TaskParameter="Registrar" PropertyName="_BundlerRegistrar" />
 			<Output TaskParameter="Verbosity" PropertyName="_BundlerVerbosity" />
 			<Output TaskParameter="XmlDefinitions" ItemName="_BundlerXmlDefinitions" />
+			<Output TaskParameter="NoStrip" PropertyName="EnableAssemblyILStripping" />
 		</ParseBundlerArguments>
 
 		<PropertyGroup>

diff --git a/msbuild/Xamarin.iOS.Tasks.Core/Tasks/ILStripBase.cs b/msbuild/Xamarin.iOS.Tasks.Core/Tasks/ILStripBase.cs
@@ -0,0 +1,35 @@
+using System.Collections.Generic;
+using System.IO;
+using Microsoft.Build.Framework;
+using Microsoft.Build.Utilities;
+
+// Normally this would be ILStrip.Tasks but ILStrip is in the global namespace
+// And having a type and the parent namespace have the same name really confuses the compiler
+namespace ILStripTasks {
+	public class ILStripBase : ILStrip
+	{
+		public string SessionId { get; set; }
+
+		[Output]
+		public ITaskItem [] StrippedAssemblies { get; set; }
+
+		public override bool Execute ()
+		{
+			var result = base.Execute ();
+
+			var stripedItems = new List<ITaskItem> ();
+
+			if (result)
+			{
+				foreach (var item in Assemblies)
+				{
+					stripedItems.Add (new TaskItem (item.GetMetadata("OutputPath")));
+				}
+			}
+
+			StrippedAssemblies = stripedItems.ToArray();
+
+			return result;
+		}
+	}
+}
diff --git a/msbuild/Xamarin.iOS.Tasks.Core/Xamarin.iOS.Tasks.Core.csproj b/msbuild/Xamarin.iOS.Tasks.Core/Xamarin.iOS.Tasks.Core.csproj
@@ -14,6 +14,7 @@
     <PackageReference Include="Microsoft.Build.Tasks.Core" Version="16.8.0" IncludeAssets="compile" />
     <PackageReference Include="Microsoft.Build.Utilities.Core" Version="16.8.0" IncludeAssets="compile" />
     <PackageReference Include="Microsoft.NET.ILLink.Tasks" Version="$(MicrosoftNETILLinkTasksPackageVersion)" />
+    <PackageReference Include="Microsoft.NET.Runtime.MonoTargets.Sdk" Version="$(MicrosoftNETILStripTasksPackageVersion)" GeneratePathProperty="true"/>
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\external\Xamarin.MacDev\Xamarin.MacDev\Xamarin.MacDev.csproj" />
@@ -24,6 +25,10 @@
       <!-- We need the net472 impl, otherwise the Build agent needs to be a net5.0 app -->
       <HintPath>$(PkgMicrosoft_NET_ILLink_Tasks)\tools\net472\ILLink.Tasks.dll</HintPath>
     </Reference>
+    <Reference Include="ILStrip">
+      <!-- We need the net472 impl, otherwise the Build agent needs to be a net5.0 app -->
+      <HintPath>$(PkgMicrosoft_NET_Runtime_MonoTargets_Sdk)\tasks\net472\ILStrip.dll</HintPath>
+    </Reference>
   </ItemGroup>
   <ItemGroup>
     <None Include="NoCode.cs">

diff --git a/msbuild/Xamarin.iOS.Tasks/Tasks/ILStrip.cs b/msbuild/Xamarin.iOS.Tasks/Tasks/ILStrip.cs
@@ -0,0 +1,25 @@
+using System.Collections.Generic;
+using System.Linq;
+using Microsoft.Build.Tasks;
+using Microsoft.Build.Framework;
+using Xamarin.Messaging.Build.Client;
+
+namespace Xamarin.MacDev.Tasks 
+{
+	public class ILStrip : ILStripTasks.ILStripBase, ITaskCallback
+	{
+		public override bool Execute ()
+		{
+			if (this.ShouldExecuteRemotely (SessionId))
+				return new TaskRunner (SessionId, BuildEngine4).RunAsync (this).Result;
+
+			return base.Execute ();
+		}
+
+		public bool ShouldCopyToBuildServer (ITaskItem item) => false;
+
+		public bool ShouldCreateOutputFile (ITaskItem item) => true;
+
+		public IEnumerable<ITaskItem> GetAdditionalItemsToBeCopied () => Enumerable.Empty<ITaskItem> ();
+	}
+}
diff --git a/msbuild/Xamarin.iOS.Tasks/Xamarin.iOS.Tasks.csproj b/msbuild/Xamarin.iOS.Tasks/Xamarin.iOS.Tasks.csproj
@@ -24,6 +24,7 @@
     <PackageReference Include="Microsoft.Build.Tasks.Core" Version="16.8.0" IncludeAssets="$(IncludeMSBuildAssets)" />
     <PackageReference Include="Microsoft.Build.Utilities.Core" Version="16.8.0" IncludeAssets="$(IncludeMSBuildAssets)" />
     <PackageReference Include="Microsoft.NET.ILLink.Tasks" Version="$(MicrosoftNETILLinkTasksPackageVersion)" />
+    <PackageReference Include="Microsoft.NET.Runtime.MonoTargets.Sdk" Version="$(MicrosoftNETILStripTasksPackageVersion)" GeneratePathProperty="true"/>
     <PackageReference Include="Xamarin.Messaging.Build.Client" Version="$(MessagingVersion)" />
   </ItemGroup>
 
@@ -32,6 +33,10 @@
     <Reference Include="ILLink.Tasks">
       <HintPath>$(PkgMicrosoft_NET_ILLink_Tasks)\tools\net472\ILLink.Tasks.dll</HintPath>
     </Reference>
+    <Reference Include="ILStrip">
+      <!-- We need the net472 impl, otherwise the Build agent needs to be a net5.0 app -->
+      <HintPath>$(PkgMicrosoft_NET_Runtime_MonoTargets_Sdk)\tasks\net472\ILStrip.dll</HintPath>
+    </Reference>
   </ItemGroup>
 
   <ItemGroup>

diff --git a/tests/dotnet/Makefile b/tests/dotnet/Makefile
@@ -57,12 +57,10 @@ build-dotnet: $(TARGETS)
 	$(DOTNET6) build size-comparison/MySingleView/dotnet/MySingleView.csproj --runtime ios-arm64 $(COMMON_ARGS) /bl:$@.binlog $(MSBUILD_VERBOSITY)
 
 run-dotnet: $(TARGETS)
-	$(DOTNET6) build -t:Run size-comparison/MySingleView/dotnet/MySingleView.csproj --runtime ios-arm64 $(COMMON_ARGS)
+	$(DOTNET6) build -t:Run size-comparison/MySingleView/dotnet/MySingleView.csproj --runtime ios-arm64 $(COMMON_ARGS) /bl:$@.binlog $(MSBUILD_VERBOSITY)
 
-# this will break the signature, so app won't run anymore. Use it only to compare final size w/legacy
-# https://github.com/xamarin/xamarin-macios/issues/11445
-strip-dotnet:
-	$(foreach file, $(wildcard size-comparison/MySingleView/dotnet/bin/iPhone/Release/net6.0-ios/ios-arm64/MySingleView.app/*.dll), mono-cil-strip $(file) $(file);)
+run-dotnet-sim: $(TARGETS)
+	$(DOTNET6) build -t:Run size-comparison/MySingleView/dotnet/MySingleView.csproj /p:Configuration=Release --runtime iossimulator-x64 /p:Platform=iPhoneSimulator /bl:$@.binlog
 
 # this target will copy NuGet.config and global.json to the directories that need it for their .NET build to work correctly.
 copy-dotnet-config: $(TARGETS)

diff --git a/tests/dotnet/README.md b/tests/dotnet/README.md
@@ -16,11 +16,4 @@ Add this option inside the `Release|iPhone` configuration of `size-comparison/My
 
 * net6
 
-**IL stripping is not yet available** so there's nothing to disable right now.
-
-If you want to compare (trimmed) size you can manually call `mono-cil-strip`
-on each assembly inside the app bundle.
-
-`make strip-dotnet` will remove the IL from the dotnet app version.
-However this is done after the code signature so it will not be possible
-to deploy and execute the app afterward. Use for binary analysis only!
+Build with `/p:EnableAssemblyILStripping=false` set. The `MtouchExtraArgs` legacy option is also honored. 
diff --git a/tests/dotnet/UnitTests/PostBuildTest.cs b/tests/dotnet/UnitTests/PostBuildTest.cs
@@ -9,6 +9,7 @@
 
 using Microsoft.Build.Framework;
 using Microsoft.Build.Logging.StructuredLogger;
+using Mono.Cecil;
 
 namespace Xamarin.Tests {
 	[TestFixture]
@@ -50,15 +51,38 @@ public void BuildIpaTest (ApplePlatform platform, string runtimeIdentifiers)
 			var project = "MySimpleApp";
 			Configuration.IgnoreIfIgnoredPlatform (platform);
 
-			var project_path = GetProjectPath (project, runtimeIdentifiers: runtimeIdentifiers, platform: platform, out var appPath);
+			var project_path = GetProjectPath (project, runtimeIdentifiers: runtimeIdentifiers, platform: platform, out var appPath, configuration: "Release");
 			Clean (project_path);
 			var properties = GetDefaultProperties (runtimeIdentifiers);
 			properties ["BuildIpa"] = "true";
+			properties ["Configuration"] = "Release";
 
 			DotNet.AssertBuild (project_path, properties);
 
 			var pkgPath = Path.Combine (appPath, "..", $"{project}.ipa");
 			Assert.That (pkgPath, Does.Exist, "pkg creation");
+
+			AssertBundleAssembliesStripStatus (appPath, true);
+		}
+
+		[Test]
+		[TestCase (ApplePlatform.iOS, "ios-arm64", true)]
+		[TestCase (ApplePlatform.iOS, "ios-arm64", false)]
+		public void AssemblyStripping (ApplePlatform platform, string runtimeIdentifiers, bool shouldStrip)
+		{
+			var project = "MySimpleApp";
+			Configuration.IgnoreIfIgnoredPlatform (platform);
+
+			var project_path = GetProjectPath (project, runtimeIdentifiers: runtimeIdentifiers, platform: platform, out var appPath);
+			Clean (project_path);
+			var properties = GetDefaultProperties (runtimeIdentifiers);
+
+			// Force EnableAssemblyILStripping since we are building debug which never will by default
+			properties ["EnableAssemblyILStripping"] = shouldStrip ? "true" : "false";
+
+			DotNet.AssertBuild (project_path, properties);
+
+			AssertBundleAssembliesStripStatus (appPath, shouldStrip);
 		}
 
 		[Test]

diff --git a/tests/dotnet/UnitTests/TestBaseClass.cs b/tests/dotnet/UnitTests/TestBaseClass.cs
@@ -36,18 +36,18 @@ protected void SetRuntimeIdentifiers (Dictionary<string, string> properties, str
 			properties [multiRid] = runtimeIdentifiers;
 		}
 
-		protected string GetProjectPath (string project, string runtimeIdentifiers, ApplePlatform platform, out string appPath, string? subdir = null)
+		protected string GetProjectPath (string project, string runtimeIdentifiers, ApplePlatform platform, out string appPath, string? subdir = null, string configuration = "Debug")
 		{
-			return GetProjectPath (project, null, runtimeIdentifiers, platform, out appPath);
+			return GetProjectPath (project, null, runtimeIdentifiers, platform, out appPath, configuration);
 		}
 
-		protected string GetProjectPath (string project, string? subdir, string runtimeIdentifiers, ApplePlatform platform, out string appPath)
+		protected string GetProjectPath (string project, string? subdir, string runtimeIdentifiers, ApplePlatform platform, out string appPath, string configuration = "Debug")
 		{
 			var rv = GetProjectPath (project, subdir, platform);
 			if (string.IsNullOrEmpty (runtimeIdentifiers))
 				runtimeIdentifiers = GetDefaultRuntimeIdentifier (platform);
 			var appPathRuntimeIdentifier = runtimeIdentifiers.IndexOf (';') >= 0 ? "" : runtimeIdentifiers;
-			appPath = Path.Combine (Path.GetDirectoryName (rv)!, "bin", "Debug", platform.ToFramework (), appPathRuntimeIdentifier, project + ".app");
+			appPath = Path.Combine (Path.GetDirectoryName (rv)!, "bin", configuration, platform.ToFramework (), appPathRuntimeIdentifier, project + ".app");
 			return rv;
 		}
 
@@ -141,6 +141,24 @@ protected string GetInfoPListPath (ApplePlatform platform, string app_directory)
 			}
 		}
 
+		protected void AssertBundleAssembliesStripStatus (string appPath, bool shouldStrip)
+		{
+			var assemblies = Directory.GetFiles (appPath, "*.dll", SearchOption.AllDirectories);
+			var assembliesWithOnlyEmptyMethods = new List<String> ();
+			foreach (var assembly in assemblies) {
+				ModuleDefinition definition = ModuleDefinition.ReadModule (assembly, new ReaderParameters { ReadingMode = ReadingMode.Deferred });
+
+				bool onlyHasEmptyMethods = definition.Assembly.MainModule.Types.All (t => 
+					t.Methods.Where (m => m.HasBody).All (m => m.Body.Instructions.Count == 1));
+				if (onlyHasEmptyMethods) {
+					assembliesWithOnlyEmptyMethods.Add (assembly);
+				}
+			}
+
+			// Some assemblies, such as Facades, will be completely empty even when not stripped
+			Assert.That (assemblies.Length == assembliesWithOnlyEmptyMethods.Count, Is.EqualTo (shouldStrip), $"Unexpected stripping status: of {assemblies.Length} assemblies {assembliesWithOnlyEmptyMethods.Count} were empty.");
+		}
+
 		protected string GetNativeExecutable (ApplePlatform platform, string app_directory)
 		{
 			var executableName = Path.GetFileNameWithoutExtension (app_directory);