Initial scaffolding and partial implementation of ilasm in C#

eng/Subsets.props

@@ -254,6 +254,7 @@
     <SubsetName Include="Tools.Cdac" Description="Diagnostic data contract reader and related projects." />
     <SubsetName Include="Tools.ILLinkTests" OnDemand="true" Description="Unit tests for the tools.illink subset." />
     <SubsetName Include="Tools.CdacTests" OnDemand="true" Description="Unit tests for the diagnostic data contract reader." />
+    <SubsetName Include="Tools.ILAsm" OnDemand="true" Description="Build only the managed ilasm tool." />
 
     <!-- Host -->
     <SubsetName Include="Host" Description="The .NET hosts, packages, hosting libraries, and tests. Equivalent to: $(DefaultHostSubsets)" />
@@ -510,7 +511,7 @@
 
   <ItemGroup Condition="$(_subset.Contains('+tools.cdac+'))">
     <ProjectToBuild Include="$(SharedNativeRoot)managed\compile-native.proj" Category="tools" />
-    
+
     <!-- Direct references to cDAC projects for packing -->
     <ProjectToBuild Include="$(SharedNativeRoot)managed\cdac\Microsoft.Diagnostics.DataContractReader\Microsoft.Diagnostics.DataContractReader.csproj;
                              $(SharedNativeRoot)managed\cdac\Microsoft.Diagnostics.DataContractReader.Abstractions\Microsoft.Diagnostics.DataContractReader.Abstractions.csproj;
@@ -547,6 +548,11 @@
       Test="true" Category="tools"/>
   </ItemGroup>
 
+  <ItemGroup Condition="$(_subset.Contains('+tools.ilasm+'))">
+    <ProjectToBuild Include="$(ToolsProjectRoot)ilasm\ILAssembler\ILAssembler.csproj" Category="tools" />
+    <ProjectToBuild Include="$(ToolsProjectRoot)ilasm\ILAssembler.Tests\ILAssembler.Tests.csproj" Category="tools" Test="true" />
+  </ItemGroup>
+
   <ItemGroup Condition="$(_subset.Contains('+clr.nativecorelib+'))">
     <ProjectToBuild Include="$(CoreClrProjectRoot)crossgen-corelib.proj" Category="clr" />
   </ItemGroup>

eng/pipelines/coreclr/ilasm.yml

@@ -8,6 +8,7 @@ pr:
     include:
     - src/coreclr/ilasm/*
     - src/coreclr/ildasm/*
+    - src/tools/ilasm/*
 
 schedules:
 - cron: "0 19 * * 6"
@@ -32,3 +33,20 @@ extends:
     - windows_x86
     - windows_arm64
     testGroup: ilasm
+
+    stages:
+      - stage: Managed_ILAsm
+        displayName: Managed IL Assembler Tests
+        dependsOn: []
+        jobs:
+          - template: /eng/pipelines/common/platform-matrix.yml
+            parameters:
+              jobTemplate: /eng/pipelines/common/global-build-job.yml
+              buildConfig: Debug
+              platforms:
+              - windows_x64
+              jobParameters:
+                nameSuffix: ILAsm
+                buildArgs: -s tools.ilasm -c $(_BuildConfig) -test
+                timeoutInMinutes: 120
+        condition: and(succeeded(), ne(variables['Build.Reason'], 'Schedule'))

eng/pipelines/coreclr/templates/jit-outerloop-pipeline.yml

@@ -4,6 +4,9 @@ parameters:
   - name: testGroup
     type: string
     default: outerloop
+  - name: stages
+    type: stageList
+    default: []
 
 extends:
   template:  /eng/pipelines/common/templates/pipeline-with-resources.yml
@@ -55,3 +58,5 @@ extends:
             testGroup: ${{ parameters.testGroup }}
             liveLibrariesBuildConfig: Release
             unifiedArtifactsName: BuildArtifacts_$(osGroup)$(osSubgroup)_$(archType)_$(_BuildConfig)
+    - ${{ each stage in parameters.stages }}:
+        - ${{ stage }}

src/tools/ilasm/ILAssembler.Tests/DocumentCompilerTests.cs

@@ -0,0 +1,53 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection.Metadata;
+using System.Reflection.Metadata.Ecma335;
+using System.Reflection.PortableExecutable;
+using System.Text;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace ILAssembler.Tests
+{
+    public class DocumentCompilerTests
+    {
+        [Fact]
+        public void SingleTypeNoMembers()
+        {
+            string source = """
+                .class public auto ansi sealed beforefieldinit Test
+                {
+                }
+                """;
+
+            using var pe = CompileAndGetReader(source, new Options());
+            var reader = pe.GetMetadataReader();
+
+            // One for the <Module> type, one for Test.
+            Assert.Equal(2, reader.TypeDefinitions.Count);
+            var typeDef = reader.GetTypeDefinition(MetadataTokens.TypeDefinitionHandle(2));
+            Assert.Equal(string.Empty, reader.GetString(typeDef.Namespace));
+            Assert.Equal("Test", reader.GetString(typeDef.Name));
+        }
+
+        private static PEReader CompileAndGetReader(string source, Options options)
+        {
+            var sourceText = new SourceText(source, "test.il");
+            var documentCompiler = new DocumentCompiler();
+            var (diagnostics, result) = documentCompiler.Compile(sourceText, _ =>
+            {
+                Assert.Fail("Expected no includes");
+                return default;
+            }, _ => { Assert.Fail("Expected no resources"); return default; }, options);
+            Assert.Empty(diagnostics);
+            Assert.NotNull(result);
+            var blobBuilder = new BlobBuilder();
+            result!.Serialize(blobBuilder);
+            return new PEReader(blobBuilder.ToImmutableArray());
+        }
+    }
+}

src/tools/ilasm/ILAssembler.Tests/ILAssembler.Tests.csproj

@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>$(NetCoreAppToolCurrent)</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\ILAssembler\ILAssembler.csproj" />
+  </ItemGroup>
+</Project>