[Build] Split _GenerateJavaStubs into independent sub-targets for incremental build performance

src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.TypeMap.LlvmIr.targets

@@ -24,25 +24,21 @@
       _PrepareNativeAssemblySources;
       $(_AfterPrepareAssemblies);
       _GetGenerateJavaStubsInputs;
+      _GetGenerateJavaCallableWrappersInputs;
+      _GetGenerateJavaStubsCoreInputs;
+      _GetGenerateTypeMappingsInputs;
+      _GetGenerateAndroidManifestInputs;
+      _GenerateJavaCallableWrappers;
+      _GenerateJavaStubsCore;
+      _GenerateTypeMappings;
+      _GenerateAndroidManifest;
     </_GenerateJavaStubsDependsOnTargets>
   </PropertyGroup>
 
-  <Target Name="_GenerateJavaStubs"
-      DependsOnTargets="$(_GenerateJavaStubsDependsOnTargets);$(BeforeGenerateAndroidManifest)"
-      Inputs="@(_GenerateJavaStubsInputs)"
-      Outputs="$(_AndroidStampDirectory)_GenerateJavaStubs.stamp">
-
-    <PropertyGroup>
-      <_ManifestOutput Condition=" '$(AndroidManifestMerger)' == 'legacy' ">$(IntermediateOutputPath)android\AndroidManifest.xml</_ManifestOutput>
-      <_ManifestOutput Condition=" '$(AndroidManifestMerger)' != 'legacy' ">$(IntermediateOutputPath)AndroidManifest.xml</_ManifestOutput>
-      <_LinkingEnabled Condition=" '$(AndroidLinkMode)' != 'None'">True</_LinkingEnabled>
-      <_LinkingEnabled Condition=" '$(AndroidLinkMode)' == 'None'">False</_LinkingEnabled>
-      <_HaveMultipleRIDs Condition=" '$(RuntimeIdentifiers)' != '' ">True</_HaveMultipleRIDs>
-      <_HaveMultipleRIDs Condition=" '$(RuntimeIdentifiers)' == '' ">False</_HaveMultipleRIDs>
-    </PropertyGroup>
-    <ItemGroup>
-      <_MergedManifestDocuments Condition=" '$(AndroidManifestMerger)' == 'legacy' " Include="@(ExtractedManifestDocuments)" />
-    </ItemGroup>
+  <Target Name="_GenerateJavaCallableWrappers"
+      DependsOnTargets="_PrepareAssemblies;_GetGenerateJavaCallableWrappersInputs"
+      Inputs="@(_GenerateJavaCallableWrappersInputs)"
+      Outputs="$(_AndroidStampDirectory)_GenerateJavaCallableWrappers.stamp">
 
     <GenerateJavaCallableWrappers
         CodeGenerationTarget="$(_AndroidJcwCodegenTarget)"
@@ -60,6 +56,16 @@
         SupportedAbis="@(_BuildTargetAbis)">
     </GenerateACWMap>
 
+    <Touch Files="$(_AndroidStampDirectory)_GenerateJavaCallableWrappers.stamp" AlwaysCreate="True" />
+  </Target>
+
+  <Target Name="_GenerateJavaStubsCore"
+      DependsOnTargets="_PrepareAssemblies;_GetGenerateJavaStubsInputs;_GetGenerateJavaStubsCoreInputs"
+      Inputs="@(_GenerateJavaStubsCoreInputs)"
+      Outputs="$(_AndroidStampDirectory)_GenerateJavaStubsCore.stamp">
+
+    <!-- GeneratedJavaFiles may be empty when _GenerateJavaCallableWrappers is skipped;
+         safe because it's only used in RunCheckedBuild validation -->
     <GenerateJavaStubs
         CodeGenerationTarget="$(_AndroidJcwCodegenTarget)"
         ResolvedAssemblies="@(_ResolvedAssemblies)"
@@ -85,6 +91,14 @@
         IntermediateOutputDirectory="$(IntermediateOutputPath)">
     </RewriteMarshalMethods>
 
+    <Touch Files="$(_AndroidStampDirectory)_GenerateJavaStubsCore.stamp" AlwaysCreate="True" />
+  </Target>
+
+  <Target Name="_GenerateTypeMappings"
+      DependsOnTargets="_GenerateJavaStubsCore;_PrepareNativeAssemblySources;_GetGenerateTypeMappingsInputs"
+      Inputs="@(_GenerateTypeMappingsInputs)"
+      Outputs="$(_AndroidStampDirectory)_GenerateTypeMappings.stamp">
+
     <GenerateTypeMappings
         AndroidRuntime="$(_AndroidRuntime)"
         Debug="$(AndroidIncludeDebugSymbols)"
@@ -96,8 +110,40 @@
         SupportedAbis="@(_BuildTargetAbis)"
         TypemapImplementation="$(_AndroidTypeMapImplementation)"
         TypemapOutputDirectory="$(_NativeAssemblySourceDir)">
+      <Output TaskParameter="JniAddNativeMethodRegistrationAttributePresent" PropertyName="_JniAddNativeMethodRegistrationAttributePresent" />
     </GenerateTypeMappings>
 
+    <!-- Persist the JNI registration flag for downstream targets that may run
+         even when this target is skipped on subsequent incremental builds -->
+    <WriteLinesToFile
+        File="$(IntermediateOutputPath)jni-registration-attribute.cache"
+        Lines="$(_JniAddNativeMethodRegistrationAttributePresent)"
+        Overwrite="true"
+        WriteOnlyWhenDifferent="true" />
+
+    <ItemGroup>
+      <FileWrites Include="@(_TypeMapAssemblySource)" />
+      <FileWrites Include="@(_TypeMapAssemblyInclude)" />
+      <FileWrites Include="@(_AndroidTypeMapping)" Condition=" '@(_AndroidTypeMapping->Count())' == '0' " />
+      <FileWrites Include="$(IntermediateOutputPath)jni-registration-attribute.cache" />
+    </ItemGroup>
+
+    <Touch Files="$(_AndroidStampDirectory)_GenerateTypeMappings.stamp" AlwaysCreate="True" />
+  </Target>
+
+  <Target Name="_GenerateAndroidManifest"
+      DependsOnTargets="_GenerateJavaStubsCore;_GetGenerateJavaStubsInputs;$(BeforeGenerateAndroidManifest);_GetGenerateAndroidManifestInputs"
+      Inputs="@(_GenerateAndroidManifestInputs)"
+      Outputs="$(_AndroidStampDirectory)_GenerateAndroidManifest.stamp">
+
+    <PropertyGroup>
+      <_ManifestOutput Condition=" '$(AndroidManifestMerger)' == 'legacy' ">$(IntermediateOutputPath)android\AndroidManifest.xml</_ManifestOutput>
+      <_ManifestOutput Condition=" '$(AndroidManifestMerger)' != 'legacy' ">$(IntermediateOutputPath)AndroidManifest.xml</_ManifestOutput>
+    </PropertyGroup>
+    <ItemGroup>
+      <_MergedManifestDocuments Condition=" '$(AndroidManifestMerger)' == 'legacy' " Include="@(ExtractedManifestDocuments)" />
+    </ItemGroup>
+
     <GenerateACWMap
         Condition=" '$(_AndroidJLOCheckedBuild)' == 'true' "
         AcwMapFile="$(_AcwMapFile)"
@@ -147,13 +193,16 @@
     </GenerateAdditionalProviderSources>
 
     <ItemGroup>
-      <FileWrites Include="@(_TypeMapAssemblySource)" />
-      <FileWrites Include="@(_TypeMapAssemblyInclude)" />
-      <FileWrites Include="@(_AndroidTypeMapping)" Condition=" '@(_AndroidTypeMapping->Count())' == '0' " />
       <FileWrites Include="$(_ManifestOutput)" />
     </ItemGroup>
 
-    <Touch Files="$(_AndroidStampDirectory)_GenerateJavaStubs.stamp" AlwaysCreate="True" />
+    <Touch Files="$(_AndroidStampDirectory)_GenerateAndroidManifest.stamp" AlwaysCreate="True" />
+  </Target>
+
+  <Target Name="_GenerateJavaStubs"
+      DependsOnTargets="$(_GenerateJavaStubsDependsOnTargets)">
+    <!-- This target is preserved for backward compatibility.
+         All work is done by the sub-targets listed in _GenerateJavaStubsDependsOnTargets. -->
   </Target>
 
   <!-- ILLink customization: custom trimmer steps, root descriptors, etc. -->

src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.TypeMap.Trimmable.targets

@@ -17,12 +17,42 @@
        tasks needed by all typemap paths, but they currently depend on NativeCodeGenState
        from the Cecil-based GenerateJavaStubs task. Extracting them into a shared target
        requires decoupling from NativeCodeGenState first. See #10807. -->
+  <Target Name="_GenerateJavaCallableWrappers"
+      DependsOnTargets="_SetLatestTargetFrameworkVersion;_PrepareAssemblies;_GetGenerateJavaCallableWrappersInputs"
+      Inputs="@(_GenerateJavaCallableWrappersInputs)"
+      Outputs="$(_AndroidStampDirectory)_GenerateJavaCallableWrappers.stamp">
+    <Message Text="Trimmable typemap: skipping _GenerateJavaCallableWrappers" Importance="High" />
+    <Touch Files="$(_AndroidStampDirectory)_GenerateJavaCallableWrappers.stamp" AlwaysCreate="True" />
+  </Target>
+
+  <Target Name="_GenerateJavaStubsCore"
+      DependsOnTargets="_SetLatestTargetFrameworkVersion;_PrepareAssemblies;_GetGenerateJavaStubsCoreInputs"
+      Inputs="@(_GenerateJavaStubsCoreInputs)"
+      Outputs="$(_AndroidStampDirectory)_GenerateJavaStubsCore.stamp">
+    <Message Text="Trimmable typemap: skipping _GenerateJavaStubsCore" Importance="High" />
+    <Touch Files="$(_AndroidStampDirectory)_GenerateJavaStubsCore.stamp" AlwaysCreate="True" />
+  </Target>
+
+  <Target Name="_GenerateTypeMappings"
+      DependsOnTargets="_SetLatestTargetFrameworkVersion;_PrepareAssemblies;_GetGenerateTypeMappingsInputs"
+      Inputs="@(_GenerateTypeMappingsInputs)"
+      Outputs="$(_AndroidStampDirectory)_GenerateTypeMappings.stamp">
+    <Message Text="Trimmable typemap: skipping _GenerateTypeMappings" Importance="High" />
+    <Touch Files="$(_AndroidStampDirectory)_GenerateTypeMappings.stamp" AlwaysCreate="True" />
+  </Target>
+
+  <Target Name="_GenerateAndroidManifest"
+      DependsOnTargets="_SetLatestTargetFrameworkVersion;_PrepareAssemblies;_GetGenerateAndroidManifestInputs"
+      Inputs="@(_GenerateAndroidManifestInputs)"
+      Outputs="$(_AndroidStampDirectory)_GenerateAndroidManifest.stamp">
+    <Message Text="Trimmable typemap: skipping _GenerateAndroidManifest" Importance="High" />
+    <Touch Files="$(_AndroidStampDirectory)_GenerateAndroidManifest.stamp" AlwaysCreate="True" />
+  </Target>
+
   <Target Name="_GenerateJavaStubs"
-      DependsOnTargets="_SetLatestTargetFrameworkVersion;_PrepareAssemblies;_GetGenerateJavaStubsInputs"
-      Inputs="@(_GenerateJavaStubsInputs)"
-      Outputs="$(_AndroidStampDirectory)_GenerateJavaStubs.stamp">
-    <Message Text="Trimmable typemap: skipping legacy _GenerateJavaStubs" Importance="High" />
-    <Touch Files="$(_AndroidStampDirectory)_GenerateJavaStubs.stamp" AlwaysCreate="True" />
+      DependsOnTargets="_SetLatestTargetFrameworkVersion;_PrepareAssemblies;_GetGenerateJavaStubsInputs;_GenerateJavaCallableWrappers;_GenerateJavaStubsCore;_GenerateTypeMappings;_GenerateAndroidManifest">
+    <!-- This target is preserved for backward compatibility.
+         In the trimmable typemap path, all sub-targets are stubs. -->
   </Target>
 
 </Project>

src/Xamarin.Android.Build.Tasks/Tasks/CompileNativeAssembly.cs

@@ -22,6 +22,7 @@ sealed class Config
 			public string? AssemblerPath;
 			public string? AssemblerOptions;
 			public string? InputSource;
+			public string? OutputFile;
 		}
 
 		[Required]
@@ -43,6 +44,14 @@ public override System.Threading.Tasks.Task RunTaskAsync ()
 
 		void RunAssembler (Config config)
 		{
+			if (config.OutputFile is not null && File.Exists (config.OutputFile)) {
+				string sourceFile = Path.Combine (WorkingDirectory, Path.GetFileName (config.InputSource));
+				if (File.Exists (sourceFile) && File.GetLastWriteTimeUtc (config.OutputFile) >= File.GetLastWriteTimeUtc (sourceFile)) {
+					LogDebugMessage ($"[LLVM llc] Skipping '{Path.GetFileName (config.InputSource)}' because '{Path.GetFileName (config.OutputFile)}' is up to date");
+					return;
+				}
+			}
+
 			var stdout_completed = new ManualResetEvent (false);
 			var stderr_completed = new ManualResetEvent (false);
 			var psi = new ProcessStartInfo () {
@@ -118,10 +127,13 @@ IEnumerable<Config> GetAssemblerConfigs ()
 				string executableDir = Path.GetDirectoryName (llcPath);
 				string executableName = MonoAndroidHelper.GetExecutablePath (executableDir, Path.GetFileName (llcPath));
 
+				string outputFilePath = Path.Combine (WorkingDirectory, sourceFile.Replace (".ll", ".o"));
+
 				yield return new Config {
 					InputSource = item.ItemSpec,
 					AssemblerPath = Path.Combine (executableDir, executableName),
 					AssemblerOptions = $"{assemblerOptions} -o={outputFile} {QuoteFileName (sourceFile)}",
+					OutputFile = outputFilePath,
 				};
 			}
 		}

src/Xamarin.Android.Build.Tasks/Tasks/GenerateNativeApplicationConfigSources.cs

@@ -57,6 +57,7 @@ public class GenerateNativeApplicationConfigSources : AndroidTask
 
 		public bool EnableMarshalMethods { get; set; }
 		public bool EnableManagedMarshalMethodsLookup { get; set; }
+		public bool JniAddNativeMethodRegistrationAttributePresent { get; set; }
 		public string? RuntimeConfigBinFilePath { get; set; }
 		public string ProjectRuntimeConfigFilePath { get; set; } = String.Empty;
 		public string? BoundExceptionType { get; set; }
@@ -251,7 +252,7 @@ public override bool RunTask ()
 					UsesAssemblyPreload = envBuilder.Parser.UsesAssemblyPreload,
 					AndroidPackageName = AndroidPackageName,
 					PackageNamingPolicy = pnp,
-					JniAddNativeMethodRegistrationAttributePresent = NativeCodeGenState.TemplateJniAddNativeMethodRegistrationAttributePresent,
+					JniAddNativeMethodRegistrationAttributePresent = JniAddNativeMethodRegistrationAttributePresent,
 					NumberOfAssembliesInApk = assemblyCount,
 					BundledAssemblyNameWidth = assemblyNameWidth,
 					NativeLibraries = uniqueNativeLibraries,
@@ -277,7 +278,7 @@ public override bool RunTask ()
 					BrokenExceptionTransitions = envBuilder.Parser.BrokenExceptionTransitions,
 					PackageNamingPolicy = pnp,
 					BoundExceptionType = boundExceptionType,
-					JniAddNativeMethodRegistrationAttributePresent = NativeCodeGenState.TemplateJniAddNativeMethodRegistrationAttributePresent,
+					JniAddNativeMethodRegistrationAttributePresent = JniAddNativeMethodRegistrationAttributePresent,
 					HaveRuntimeConfigBlob = haveRuntimeConfigBlob,
 					NumberOfAssembliesInApk = assemblyCount,
 					BundledAssemblyNameWidth = assemblyNameWidth,

src/Xamarin.Android.Build.Tasks/Tasks/GenerateTypeMappings.cs

@@ -31,6 +31,9 @@ public class GenerateTypeMappings : AndroidTask
 	[Required]
 	public string IntermediateOutputDirectory { get; set; } = "";
 
+	[Output]
+	public bool JniAddNativeMethodRegistrationAttributePresent { get; set; }
+
 	public bool SkipJniAddNativeMethodRegistrationAttributeScan { get; set; }
 
 	[Required]
@@ -102,6 +105,7 @@ void GenerateTypeMap (AndroidTargetArch arch, List<ITaskItem> assemblies)
 
 		// Set for use by <GeneratePackageManagerJava/> task later
 		NativeCodeGenState.TemplateJniAddNativeMethodRegistrationAttributePresent = state.JniAddNativeMethodRegistrationAttributePresent;
+		JniAddNativeMethodRegistrationAttributePresent = NativeCodeGenState.TemplateJniAddNativeMethodRegistrationAttributePresent;
 
 		AddOutputTypeMaps (tmg, state.TargetArch);
 	}
@@ -126,8 +130,10 @@ void GenerateAllTypeMappingsFromNativeState (bool useMarshalMethods)
 			throw new InvalidOperationException ($"Internal error: no native code generator state defined");
 
 		// Set for use by <GenerateNativeApplicationConfigSources/> task later
-		if (useMarshalMethods)
+		if (useMarshalMethods) {
 			NativeCodeGenState.TemplateJniAddNativeMethodRegistrationAttributePresent = templateCodeGenState.JniAddNativeMethodRegistrationAttributePresent;
+			JniAddNativeMethodRegistrationAttributePresent = NativeCodeGenState.TemplateJniAddNativeMethodRegistrationAttributePresent;
+		}
 	}
 
 	void GenerateTypeMapFromNativeState (NativeCodeGenState state, bool useMarshalMethods)

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/AndroidUpdateResourcesTest.cs

@@ -543,7 +543,7 @@ protected override void OnClick()
 				Assert.IsFalse (StringAssertEx.ContainsText (b.LastBuildOutput, "AndroidResgen: Warning while updating Resource XML"),
 					"Warning while processing resources should not have been raised.");
 				Assert.IsTrue (b.Build (proj, doNotCleanupOnUpdate: true), "Build should have succeeded.");
-				Assert.IsTrue (b.Output.IsTargetSkipped ("_GenerateJavaStubs"), "Target _GenerateJavaStubs should have been skipped");
+				Assert.IsTrue (b.Output.IsTargetSkipped ("_GenerateJavaStubsCore"), "Target _GenerateJavaStubsCore should have been skipped");
 
 				lib.Touch ("CustomTextView.cs");
 

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/IncrementalBuildTest.cs

@@ -746,7 +746,7 @@ public void ProduceReferenceAssembly ([Values] AndroidRuntime runtime)
 				appBuilder.Output.AssertTargetIsSkipped ("CoreCompile");
 				appBuilder.Output.AssertTargetIsSkipped ("_BuildLibraryImportsCache");
 				appBuilder.Output.AssertTargetIsSkipped ("_ResolveLibraryProjectImports");
-				appBuilder.Output.AssertTargetIsSkipped ("_GenerateJavaStubs");
+				appBuilder.Output.AssertTargetIsSkipped ("_GenerateJavaStubsCore");
 
 				appBuilder.Output.AssertTargetIsPartiallyBuilt (KnownTargets.LinkAssembliesNoShrink);
 
@@ -1237,7 +1237,10 @@ public void GenerateJavaStubsAndAssembly ([Values] bool isRelease, [Values] Andr
 			}
 
 			var targets = new [] {
-				"_GenerateJavaStubs",
+				"_GenerateJavaCallableWrappers",
+				"_GenerateJavaStubsCore",
+				"_GenerateTypeMappings",
+				"_GenerateAndroidManifest",
 				"_GeneratePackageManagerJava",
 			};
 			var proj = new XamarinAndroidApplicationProject {
@@ -1289,6 +1292,34 @@ public void GenerateJavaStubsAndAssembly ([Values] bool isRelease, [Values] Andr
 			}
 		}
 
+		[Test]
+		public void GenerateJavaStubsSubTargetIncrementality ([Values (false, true)] bool isRelease)
+		{
+			// Test that all sub-targets correctly skip on no-change rebuilds.
+			var targets = new [] {
+				"_GenerateJavaCallableWrappers",
+				"_GenerateJavaStubsCore",
+				"_GenerateTypeMappings",
+				"_GenerateAndroidManifest",
+			};
+			var proj = new XamarinAndroidApplicationProject {
+				IsRelease = isRelease,
+			};
+
+			using (var b = CreateApkBuilder ()) {
+				Assert.IsTrue (b.Build (proj), "first build should have succeeded.");
+				foreach (var target in targets) {
+					Assert.IsFalse (b.Output.IsTargetSkipped (target), $"first build: `{target}` should *not* be skipped!");
+				}
+
+				// No-change rebuild: all sub-targets should skip
+				Assert.IsTrue (b.Build (proj, doNotCleanupOnUpdate: true, saveProject: false), "no-change rebuild should have succeeded.");
+				foreach (var target in targets) {
+					Assert.IsTrue (b.Output.IsTargetSkipped (target), $"no-change: `{target}` should be skipped!");
+				}
+			}
+		}
+
 		readonly string [] ExpectedAssemblyFiles = new [] {
 			Path.Combine ("android", "environment.@ABI@.o"),
 			Path.Combine ("android", "environment.@ABI@.ll"),
@@ -1683,7 +1714,7 @@ public void AndroidResourceChange ([Values] AndroidRuntime runtime)
 
 				// TODO: NativeAOT doesn't skip this target
 				if (runtime != AndroidRuntime.NativeAOT) {
-					builder.Output.AssertTargetIsSkipped ("_GenerateJavaStubs");
+					builder.Output.AssertTargetIsSkipped ("_GenerateJavaStubsCore");
 				}
 				builder.Output.AssertTargetIsSkipped ("_CompileJava");
 				builder.Output.AssertTargetIsSkipped ("_CompileToDalvik");