feat: support NativeAOT-LLVM backend

docs/.vitepress/config.ts

@@ -60,7 +60,8 @@ export default defineConfig({
                         { text: "Interop Instances", link: "/guide/interop-instances" },
                         { text: "Emit Preferences", link: "/guide/emit-prefs" },
                         { text: "Build Configuration", link: "/guide/build-config" },
-                        { text: "Sideloading Binaries", link: "/guide/sideloading" }
+                        { text: "Sideloading Binaries", link: "/guide/sideloading" },
+                        { text: "NativeAOT-LLVM", link: "/guide/llvm" }
                     ]
                 },
                 {

docs/guide/build-config.md

@@ -7,6 +7,7 @@ Build and publish related options are configured in `.csproj` file via MSBuild p
 | BootsharpName               | bootsharp  | Name of the generated JavaScript module.                     |
 | BootsharpEmbedBinaries      | true       | Whether to embed binaries to the JavaScript module file.     |
 | BootsharpAggressiveTrimming | false      | Whether to disable some .NET features to reduce binary size. |
+| BootsharpLLVM               | false      | Enable experimental [NativeAOT-LLVM](/guide/llvm) backend.   |
 | BootsharpBundleCommand      | npx rollup | The command to bundle generated JavaScrip solution.          |
 | BootsharpPublishDirectory   | /bin       | Directory to publish generated JavaScript module.            |
 | BootsharpTypesDirectory     | /types     | Directory to publish type declarations.                      |

docs/guide/llvm.md

@@ -0,0 +1,61 @@
+# NativeAOT-LLVM
+
+Starting with v0.6.0 Bootsharp supports .NET's experimental [NativeAOT-LLVM](https://github.com/dotnet/runtimelab/tree/feature/NativeAOT-LLVM) backend.
+
+By default, when targeting `browser-wasm`, .NET is using the Mono runtime, even when compiled in AOT mode. Compared to the modern NativeAOT (previously CoreRT) runtime, Mono's performance is lacking in speed, binary size and compilation times. NativeAOT-LLVM backend not only uses the modern runtime instead of Mono, but also optimizes it with the [LLVM](https://llvm.org) toolchain, further improving the performance.
+
+Below is a benchmark comparing interop and compute performance of various languages and .NET versions compiled to WASM to give you a rough idea on the differences:
+
+|             | Rust  | .NET LLVM | .NET AOT  | Go      |
+|-------------|-------|-----------|-----------|---------|
+| Echo Number | `1.0` | `11.9`    | `21.1`    | `718.7` |
+| Echo Struct | `1.0` | `1.6`     | `4.3`     | `20.8`  |
+| Fibonacci   | `1.0` | `1.1`     | `1.5`     | `3.8`   |
+
+— the results are relative to the Rust baseline (lower is better). Sources of the benchmark are here: https://github.com/elringus/bootsharp/tree/main/samples/bench.
+
+## Setup
+
+Use following `.csproj` as a reference for enabling NativeAOT-LLVM with Bootsharp:
+
+```xml
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <!-- Notice '-browser' postfix. -->
+        <TargetFramework>net9.0-browser</TargetFramework>
+        <RuntimeIdentifier>browser-wasm</RuntimeIdentifier>
+        <!-- Let Bootsharp know you're using the LLVM backend. -->
+        <BootsharpLLVM>true</BootsharpLLVM>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <PackageReference Include="Bootsharp" Version="*-*"/>
+    </ItemGroup>
+
+    <!-- Below are properties required to enable LLVM backend. -->
+    <!-- Due to experimental nature of the project, specifics may change over time. -->
+
+    <PropertyGroup>
+        <PublishTrimmed>true</PublishTrimmed>
+        <DotNetJsApi>true</DotNetJsApi>
+        <DebugType>none</DebugType>
+        <EmccFlags>$(EmccFlags) -O3</EmccFlags> <!-- optimize speed; use -Oz for min. size -->
+        <UsingBrowserRuntimeWorkload>false</UsingBrowserRuntimeWorkload>
+        <RestoreAdditionalProjectSources>
+            https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-experimental/nuget/v3/index.json;
+        </RestoreAdditionalProjectSources>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <PackageReference Include="Microsoft.DotNet.ILCompiler.LLVM" Version="10.0.0-*"/>
+        <PackageReference Condition="'$([MSBuild]::IsOSPlatform(&quot;Windows&quot;))' == 'true'" Include="runtime.win-x64.Microsoft.DotNet.ILCompiler.LLVM" Version="10.0.0-*"/>
+        <PackageReference Condition="'$([MSBuild]::IsOSPlatform(&quot;Windows&quot;))' == 'false'" Include="runtime.linux-x64.Microsoft.DotNet.ILCompiler.LLVM" Version="10.0.0-*"/>
+        <EmscriptenEnvVars Include="DOTNET_EMSCRIPTEN_LLVM_ROOT=$(EmscriptenUpstreamBinPath)"/>
+        <EmscriptenEnvVars Include="DOTNET_EMSCRIPTEN_BINARYEN_ROOT=$(EmscriptenSdkToolsPath)"/>
+        <EmscriptenEnvVars Include="DOTNET_EMSCRIPTEN_NODE_JS=$(EmscriptenNodeBinPath)node$(ExecutableExtensionName)"/>
+        <EmscriptenEnvVars Include="EM_CACHE=$(EmscriptenCacheSdkCacheDir)"/>
+    </ItemGroup>
+
+</Project>
+```

samples/bench/bench.mjs

@@ -19,7 +19,7 @@ if (!lang || lang.toLowerCase() === "rust")
 if (!lang || lang.toLowerCase() === "llvm")
     await run(".NET LLVM", await initDotNetLLVM());
 if (!lang || lang.toLowerCase() === "net")
-    await run(".NET", await initDotNet());
+    await run(".NET AOT", await initDotNet());
 if (!lang || lang.toLowerCase() === "boot")
     await run("Bootsharp", await initBootsharp());
 if (!lang || lang.toLowerCase() === "go")

samples/bench/bootsharp/Boot.csproj

@@ -1,12 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFramework>net9.0</TargetFramework>
-        <Configuration>Release</Configuration>
+        <TargetFramework>net9.0-browser</TargetFramework>
         <RuntimeIdentifier>browser-wasm</RuntimeIdentifier>
-        <RunAOTCompilation>true</RunAOTCompilation>
-        <OptimizationPreference>Speed</OptimizationPreference>
-        <WasmEnableSIMD>true</WasmEnableSIMD>
     </PropertyGroup>
 
     <ItemGroup>
@@ -15,4 +11,28 @@
         <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="*"/>
     </ItemGroup>
 
+    <!-- https://github.com/dotnet/runtime/issues/113979#issuecomment-2759220563 -->
+
+    <PropertyGroup>
+        <BootsharpLLVM>true</BootsharpLLVM>
+        <PublishTrimmed>true</PublishTrimmed>
+        <DotNetJsApi>true</DotNetJsApi>
+        <DebugType>none</DebugType>
+        <EmccFlags>$(EmccFlags) -O3</EmccFlags>
+        <UsingBrowserRuntimeWorkload>false</UsingBrowserRuntimeWorkload>
+        <RestoreAdditionalProjectSources>
+            https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-experimental/nuget/v3/index.json;
+        </RestoreAdditionalProjectSources>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <PackageReference Include="Microsoft.DotNet.ILCompiler.LLVM" Version="10.0.0-*"/>
+        <PackageReference Condition="'$([MSBuild]::IsOSPlatform(&quot;Windows&quot;))' == 'true'" Include="runtime.win-x64.Microsoft.DotNet.ILCompiler.LLVM" Version="10.0.0-*"/>
+        <PackageReference Condition="'$([MSBuild]::IsOSPlatform(&quot;Windows&quot;))' == 'false'" Include="runtime.linux-x64.Microsoft.DotNet.ILCompiler.LLVM" Version="10.0.0-*"/>
+        <EmscriptenEnvVars Include="DOTNET_EMSCRIPTEN_LLVM_ROOT=$(EmscriptenUpstreamBinPath)"/>
+        <EmscriptenEnvVars Include="DOTNET_EMSCRIPTEN_BINARYEN_ROOT=$(EmscriptenSdkToolsPath)"/>
+        <EmscriptenEnvVars Include="DOTNET_EMSCRIPTEN_NODE_JS=$(EmscriptenNodeBinPath)node$(ExecutableExtensionName)"/>
+        <EmscriptenEnvVars Include="EM_CACHE=$(EmscriptenCacheSdkCacheDir)"/>
+    </ItemGroup>
+
 </Project>

samples/bench/dotnet-llvm/Program.cs

@@ -10,7 +10,6 @@ public struct Data
     public string[] Messages;
 }
 
-
 [JsonSerializable(typeof(Data))]
 internal partial class SourceGenerationContext : JsonSerializerContext;
 

samples/bench/readme.md

@@ -14,8 +14,8 @@ All results are relative to the Rust baseline (lower is better).
 
 ## 2024 (.NET 9)
 
-|             | Rust  | .NET LLVM | .NET   | Bootsharp | Go      |
-|-------------|-------|-----------|--------|-----------|---------|
-| Echo Number | `1.0` | `14.4`    | `21.1` | `25.7`    | `718.7` |
-| Echo Struct | `1.0` | `1.5`     | `4.3`  | `4.9`     | `20.8`  |
-| Fibonacci   | `1.0` | `1.1`     | `1.5`  | `1.6`     | `3.8`   |
+|             | Rust  | .NET LLVM | Bootsharp | .NET AOT  | Go      |
+|-------------|-------|-----------|-----------|-----------|---------|
+| Echo Number | `1.0` | `11.9`    | `11.9`    | `21.1`    | `718.7` |
+| Echo Struct | `1.0` | `1.6`     | `1.6`     | `4.3`     | `20.8`  |
+| Fibonacci   | `1.0` | `1.1`     | `1.5`     | `1.5`     | `3.8`   |

samples/trimming/README.md

@@ -6,7 +6,7 @@ To test and measure build size:
 
 ### Measurements (KB)
 
-| .NET  | Raw   | Brotli |
-|-------|-------|--------|
-| 8.0.1 | 2,298 | 739    |
-| 9.0.1 | 2,369 | 761    |
+|             | Raw   | Brotli |
+|-------------|-------|--------|
+| .NET 8      | 2,298 | 739    |
+| .NET 9 LLVM | 1,749 | 520    |

samples/trimming/cs/Program.cs

@@ -1,9 +1,12 @@
 using Bootsharp;
 
-Log("Hello from .NET!");
-
 public static partial class Program
 {
+    public static void Main ()
+    {
+        Log("Hello from .NET!");
+    }
+
     [JSFunction]
     public static partial void Log (string message);
 }

samples/trimming/cs/Trimming.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFramework>net9.0</TargetFramework>
+        <TargetFramework>net9.0-browser</TargetFramework>
         <RuntimeIdentifier>browser-wasm</RuntimeIdentifier>
         <!-- Not embedding binaries to source module reduces build size by ~30%. -->
         <BootsharpEmbedBinaries>false</BootsharpEmbedBinaries>
@@ -19,4 +19,28 @@
               WorkingDirectory="$(BootsharpPublishDirectory)"/>
     </Target>
 
+    <!-- Using experimental NativeAOT-LLM backend, which yeilds a smaller WASM binary. -->
+
+    <PropertyGroup>
+        <BootsharpLLVM>true</BootsharpLLVM>
+        <PublishTrimmed>true</PublishTrimmed>
+        <DotNetJsApi>true</DotNetJsApi>
+        <DebugType>none</DebugType>
+        <EmccFlags>$(EmccFlags) -Oz</EmccFlags> <!-- optimize for smaller binary -->
+        <UsingBrowserRuntimeWorkload>false</UsingBrowserRuntimeWorkload>
+        <RestoreAdditionalProjectSources>
+            https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-experimental/nuget/v3/index.json;
+        </RestoreAdditionalProjectSources>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <PackageReference Include="Microsoft.DotNet.ILCompiler.LLVM" Version="10.0.0-*"/>
+        <PackageReference Condition="'$([MSBuild]::IsOSPlatform(&quot;Windows&quot;))' == 'true'" Include="runtime.win-x64.Microsoft.DotNet.ILCompiler.LLVM" Version="10.0.0-*"/>
+        <PackageReference Condition="'$([MSBuild]::IsOSPlatform(&quot;Windows&quot;))' == 'false'" Include="runtime.linux-x64.Microsoft.DotNet.ILCompiler.LLVM" Version="10.0.0-*"/>
+        <EmscriptenEnvVars Include="DOTNET_EMSCRIPTEN_LLVM_ROOT=$(EmscriptenUpstreamBinPath)"/>
+        <EmscriptenEnvVars Include="DOTNET_EMSCRIPTEN_BINARYEN_ROOT=$(EmscriptenSdkToolsPath)"/>
+        <EmscriptenEnvVars Include="DOTNET_EMSCRIPTEN_NODE_JS=$(EmscriptenNodeBinPath)node$(ExecutableExtensionName)"/>
+        <EmscriptenEnvVars Include="EM_CACHE=$(EmscriptenCacheSdkCacheDir)"/>
+    </ItemGroup>
+
 </Project>

src/cs/Bootsharp.Publish.Test/Pack/PackTest.cs

@@ -45,6 +45,7 @@ protected override void AddAssembly (string assemblyName, params MockSource[] so
         BuildEngine = Engine,
         TrimmingEnabled = false,
         EmbedBinaries = false,
-        Threading = false
+        Threading = false,
+        LLVM = false
     };
 }

src/cs/Bootsharp.Publish.Test/Pack/SolutionInspectionTest.cs

@@ -25,4 +25,52 @@ public void WhenAssemblyInspectionFailsWarningIsLogged ()
         Execute();
         Assert.Contains(Engine.Warnings, w => w.Contains("Failed to inspect 'foo.dll' assembly"));
     }
+
+    [Fact]
+    public void IgnoresAssembliesNotPresentInBuildDirectory ()
+    {
+        var buildDir = $"{Project.Root}/build";
+        Task.BuildDirectory = buildDir;
+        Directory.CreateDirectory(buildDir);
+        File.WriteAllText($"{buildDir}/foo.wasm", "");
+
+        foreach (var file in Directory.EnumerateFiles(Project.Root))
+            File.WriteAllText($"{buildDir}/{Path.GetFileName(file)}", File.ReadAllText(file));
+
+        AddAssembly("foo.dll",
+            WithClass("[JSInvokable] public static void InvFoo () {}")
+        );
+        AddAssembly("bar.dll",
+            WithClass("[JSInvokable] public static void InvBar () {}")
+        );
+        Execute();
+
+        Assert.Contains(Engine.Messages, w => w.Contains("foo"));
+        Assert.DoesNotContain(Engine.Messages, w => w.Contains("bar"));
+    }
+
+    [Fact]
+    public void DoesntIgnoreAssembliesWhenLLVM ()
+    {
+        Task.LLVM = true;
+
+        var buildDir = $"{Project.Root}/build";
+        Task.BuildDirectory = buildDir;
+        Directory.CreateDirectory(buildDir);
+        File.WriteAllText($"{buildDir}/foo.wasm", "");
+
+        foreach (var file in Directory.EnumerateFiles(Project.Root))
+            File.WriteAllText($"{buildDir}/{Path.GetFileName(file)}", File.ReadAllText(file));
+
+        AddAssembly("foo.dll",
+            WithClass("[JSInvokable] public static void InvFoo () {}")
+        );
+        AddAssembly("bar.dll",
+            WithClass("[JSInvokable] public static void InvBar () {}")
+        );
+        Execute();
+
+        Assert.Contains(Engine.Messages, w => w.Contains("foo"));
+        Assert.Contains(Engine.Messages, w => w.Contains("bar"));
+    }
 }

src/cs/Bootsharp.Publish/Pack/BootsharpPack.cs

@@ -11,6 +11,7 @@ public sealed class BootsharpPack : Microsoft.Build.Utilities.Task
     public required bool TrimmingEnabled { get; set; }
     public required bool EmbedBinaries { get; set; }
     public required bool Threading { get; set; }
+    public required bool LLVM { get; set; }
 
     public override bool Execute ()
     {
@@ -32,13 +33,18 @@ private Preferences ResolvePreferences ()
     private SolutionInspection InspectSolution (Preferences prefs)
     {
         var inspector = new SolutionInspector(prefs, EntryAssemblyName);
-        // Assemblies in publish dir are trimmed and don't contain some data (eg, method arg names).
-        // While the inspected dir contains extra assemblies we don't need in build. Hence the filtering.
-        var included = Directory.GetFiles(BuildDirectory, "*.wasm").Select(Path.GetFileNameWithoutExtension).ToHashSet();
-        var inspected = Directory.GetFiles(InspectedDirectory, "*.dll").Where(p => included.Contains(Path.GetFileNameWithoutExtension(p)));
-        var inspection = inspector.Inspect(InspectedDirectory, inspected);
+        var inspection = inspector.Inspect(InspectedDirectory, GetFiles());
         new InspectionReporter(Log).Report(inspection);
         return inspection;
+
+        IEnumerable<string> GetFiles ()
+        {
+            if (LLVM) return Directory.GetFiles(InspectedDirectory, "*.dll");
+            // Assemblies in publish dir are trimmed and don't contain some data (eg, method arg names).
+            // While the inspected dir contains extra assemblies we don't need in build. Hence the filtering.
+            var included = Directory.GetFiles(BuildDirectory, "*.wasm").Select(Path.GetFileNameWithoutExtension).ToHashSet();
+            return Directory.GetFiles(InspectedDirectory, "*.dll").Where(p => included.Contains(Path.GetFileNameWithoutExtension(p)));
+        }
     }
 
     private void GenerateBindings (Preferences prefs, SolutionInspection inspection)

src/cs/Bootsharp/Bootsharp.csproj

@@ -2,11 +2,9 @@
 
     <PropertyGroup>
         <TargetFramework>net9.0</TargetFramework>
-        <Nullable>enable</Nullable>
-        <ImplicitUsings>enable</ImplicitUsings>
         <AssemblyTitle>Bootsharp</AssemblyTitle>
         <PackageId>Bootsharp</PackageId>
-        <Description>Compile C# solution into single-file ES module with auto-generated JavaScript bindings and type definitions.</Description>
+        <Description>Use C# in web apps with comfort.</Description>
         <NoWarn>NU5100</NoWarn>
     </PropertyGroup>
 
@@ -15,15 +13,12 @@
     </ItemGroup>
 
     <ItemGroup>
-        <AssemblyAttribute Include="System.Runtime.Versioning.SupportedOSPlatform">
-            <_Parameter1>browser</_Parameter1>
-        </AssemblyAttribute>
         <Content Include="Build/**" Pack="true" PackagePath="build/"/>
         <Content Include="../../../src/js/dist/**" Pack="true" PackagePath="js/" Visible="false"/>
     </ItemGroup>
 
     <Target Name="PackPublisher" BeforeTargets="CoreCompile">
-        <MSBuild Projects="../Bootsharp.Publish/Bootsharp.Publish.csproj" Targets="Publish;PublishItemsOutputGroup" Properties="Configuration=Release">
+        <MSBuild Projects="../Bootsharp.Publish/Bootsharp.Publish.csproj" Targets="Publish;PublishItemsOutputGroup">
             <Output TaskParameter="TargetOutputs" ItemName="_TasksProjectOutputs"/>
         </MSBuild>
         <ItemGroup>

src/cs/Bootsharp/Build/Bootsharp.props

@@ -10,13 +10,16 @@
         <InvariantGlobalization>true</InvariantGlobalization>
         <WasmGenerateAppBundle>true</WasmGenerateAppBundle>
         <WasmEnableLegacyJsInterop>false</WasmEnableLegacyJsInterop>
+        <WasmEnableSIMD>true</WasmEnableSIMD>
 
         <!-- Name of the generated JavaScript module; 'bootsharp' by default. -->
         <BootsharpName>bootsharp</BootsharpName>
         <!-- Whether to embed binaries to the JavaScript module file (true or false); true by default. -->
         <BootsharpEmbedBinaries>true</BootsharpEmbedBinaries>
         <!-- Whether to disable some .NET features to reduce binary size (true or false); false by default. -->
         <BootsharpAggressiveTrimming>false</BootsharpAggressiveTrimming>
+        <!-- Whether to app is built with the new experimental NativeAOT-LLVM backend; false by default. -->
+        <BootsharpLLVM>false</BootsharpLLVM>
         <!-- The command to run when compiling/bundling generated JavaScrip solution. -->
         <BootsharpBundleCommand/>
         <!-- Directory to publish generated JavaScript module; 'base-output/module-name' by default. -->