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[WIP] Enable wasm-tools workload for CoreCLR WASM targets #130226

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0d0bf9d
Prototype: Enable wasm-tools workload for CoreCLR WASM targets
lewing Jul 5, 2026
873e867
Fix BrowserWasmApp.CoreCLR.targets for workload import path
lewing Jul 5, 2026
daa5eb7
Fix CoreCLR WASM runtime pack and test issues
lewing Jul 5, 2026
fd3b441
Fix static web asset ordering for CoreCLR WASM native relink
lewing Jul 5, 2026
01d60f4
Fix satellite assembly handling in CoreCLR WASM nested publish
lewing Jul 5, 2026
0b6d888
Implement struct return thunks in InterpToNativeGenerator
lewing Jul 5, 2026
f5c0e67
Fix duplicate libminipal.a in runtime pack packaging
lewing Jul 6, 2026
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73 changes: 68 additions & 5 deletions src/mono/browser/build/BrowserWasmApp.CoreCLR.targets
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Expand Up @@ -75,8 +75,12 @@
<WasmEnvironmentVariable Condition="'$(_WasmPerfInstInterval)' != ''" Include="DOTNET_EventPipeThreadSamplingRate" Value="$(_WasmPerfInstInterval)" />
</ItemGroup>

<!-- Import shared native.wasm.targets for Emscripten SDK, ICU, exported functions/methods -->
<Import Project="$(RepositoryEngineeringDir)native.wasm.targets" />
<!-- Import shared native.wasm.targets for Emscripten SDK, ICU, exported functions/methods.
Only available in-tree (RepositoryEngineeringDir is set by the build system).
For the workload path we use EmSdkRepo.Defaults.props and inline the exported
functions/methods below. -->
<Import Project="$(RepositoryEngineeringDir)native.wasm.targets"
Condition="'$(RepositoryEngineeringDir)' != '' and Exists('$(RepositoryEngineeringDir)native.wasm.targets')" />

<!-- Derive Emscripten paths from EMSDK_PATH when workload paths are not set -->
<Import Project="$(MSBuildThisFileDirectory)EmSdkRepo.Defaults.props"
Expand All @@ -92,6 +96,55 @@
TaskFactory="TaskHostFactory"
Condition="'$(WasmAppBuilderTasksAssemblyPath)' != ''" />

<!-- Exported runtime methods and functions for the emcc link step.

@pavelsavara pavelsavara Jul 6, 2026

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In Mono we store some of the build/link flags as json file and restore it into MSBuild properties. I don't remember what was our original motivation for that. Maybe DRY ?

In the in-tree path native.wasm.targets also defines a GenerateEmccExports target
with the same items plus NativeCMakeArg entries; the last definition wins in MSBuild
and the CMake args are unused during app relink, so the override is harmless. -->
<Target Name="GenerateEmccExports"
Condition="'$(TargetsBrowser)' == 'true'">
<ItemGroup>
<EmccExportedRuntimeMethod Include="FS" />
<EmccExportedRuntimeMethod Include="HEAP8" />
<EmccExportedRuntimeMethod Include="HEAP16" />
<EmccExportedRuntimeMethod Include="HEAPU8" />
<EmccExportedRuntimeMethod Include="HEAPU16" />
<EmccExportedRuntimeMethod Include="HEAP32" />
<EmccExportedRuntimeMethod Include="HEAPU32" />
<EmccExportedRuntimeMethod Include="HEAPF32" />
<EmccExportedRuntimeMethod Include="HEAPF64" />
<EmccExportedRuntimeMethod Include="HEAP64" />
<EmccExportedRuntimeMethod Include="HEAPU64" />
<EmccExportedRuntimeMethod Include="out" />
<EmccExportedRuntimeMethod Include="err" />
<EmccExportedRuntimeMethod Include="ccall" />
<EmccExportedRuntimeMethod Include="cwrap" />
<EmccExportedRuntimeMethod Include="setValue" />
<EmccExportedRuntimeMethod Include="getValue" />
<EmccExportedRuntimeMethod Include="UTF8ToString" />
<EmccExportedRuntimeMethod Include="UTF8ArrayToString" />
<EmccExportedRuntimeMethod Include="lengthBytesUTF8" />
<EmccExportedRuntimeMethod Include="stringToUTF8Array" />
<EmccExportedRuntimeMethod Include="safeSetTimeout" />
<EmccExportedRuntimeMethod Include="runtimeKeepalivePush" />
<EmccExportedRuntimeMethod Include="runtimeKeepalivePop" />
<EmccExportedRuntimeMethod Include="abort" />

<EmccExportedFunction Include="_free" />
<EmccExportedFunction Include="_htons" />
<EmccExportedFunction Include="_malloc" />
<EmccExportedFunction Include="_sbrk" />
<EmccExportedFunction Include="_memalign" />
<EmccExportedFunction Include="_posix_memalign" />
<EmccExportedFunction Include="_memset" />
<EmccExportedFunction Include="_ntohs" />
<EmccExportedFunction Include="stackAlloc" />
<EmccExportedFunction Include="stackRestore" />
<EmccExportedFunction Include="stackSave" />
<EmccExportedFunction Include="___stack_pointer" />
<EmccExportedFunction Include="___coreclr_wasm_rtlrestorecontext_tag" />
</ItemGroup>
</Target>

<!-- Allow running/debugging from VS -->
<ItemGroup>
<ProjectCapability Include="DotNetCoreWeb"/>
Expand Down Expand Up @@ -177,7 +230,7 @@
served binary would be the original (runtime pack) dotnet.native.wasm. -->
<Target Name="_CoreCLRWasmNativeForBuild"
DependsOnTargets="WasmBuildApp"
BeforeTargets="_ResolveWasmOutputs"
BeforeTargets="_ComputeWasmBuildCandidates;_ResolveWasmOutputs"
Condition="'$(IsBrowserWasmProject)' == 'true' and
'$(WasmBuildingForNestedPublish)' != 'true' and
'$(WasmBuildOnlyAfterPublish)' != 'true' and
Expand Down Expand Up @@ -232,7 +285,7 @@
_GatherWasmFilesToBuild (unlike _ComputeWasmBuildCandidates) does not pull it in on its own.
-->
<Target Name="_CoreCLRResolveRuntimePackVsAppLocalConflicts"
BeforeTargets="_ComputeWasmBuildCandidates;_GatherWasmFilesToBuild"
BeforeTargets="_ComputeWasmBuildCandidates;_GatherWasmFilesToBuild;_CoreCLRGatherWasmFiles"
DependsOnTargets="ResolveReferences"
Condition="'$(IsBrowserWasmProject)' == 'true'">
<PropertyGroup>
Expand Down Expand Up @@ -318,7 +371,7 @@
<_CoreCLRWasmBuildAppCoreDependsOn>
_CoreCLRWasmInitialize;
_CoreCLRSetupEmscripten;
_GatherWasmFilesToBuild;
_CoreCLRGatherWasmFiles;
_CoreCLRPrepareForNativeBuild;
_CoreCLRGenerateManagedToNative;
_CoreCLRWriteCompileRsp;
Expand All @@ -334,6 +387,16 @@
Condition="'$(WasmBuildNative)' == 'true'"
DependsOnTargets="$(_CoreCLRWasmBuildAppCoreDependsOn)" />

<!-- During a nested publish, _GatherWasmFilesToPublish already populated
WasmAssembliesToBundle from ResolvedFileToPublish (which includes app
satellite assemblies). Calling _GatherWasmFilesToBuild would overwrite
that list with build-time items (IntermediateAssembly + ReferenceCopyLocalPaths)
which omit app satellites, causing ComputeWasmPublishAssets to fail.
Only call the SDK's _GatherWasmFilesToBuild for non-publish builds. -->
<Target Name="_CoreCLRGatherWasmFiles"
DependsOnTargets="_GatherWasmFilesToBuild"
Condition="'$(WasmBuildingForNestedPublish)' != 'true'" />

<!-- ======================== Initialize ======================== -->

<Target Name="_CoreCLRWasmInitialize">
Expand Down
1 change: 1 addition & 0 deletions ...nuget/Microsoft.NET.Runtime.WebAssembly.Sdk/Microsoft.NET.Runtime.WebAssembly.Sdk.pkgproj
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Expand Up @@ -17,6 +17,7 @@

<PackageFile Include="$(BrowserProjectRoot)build\BrowserWasmApp.props" TargetPath="Sdk" />
<PackageFile Include="$(BrowserProjectRoot)build\BrowserWasmApp.targets" TargetPath="Sdk" />
<PackageFile Include="$(BrowserProjectRoot)build\BrowserWasmApp.CoreCLR.targets" TargetPath="Sdk" />

<PackageFile Include="$(WasmProjectRoot)build\WasmApp.Common.props" TargetPath="Sdk" />
<PackageFile Include="$(WasmProjectRoot)build\WasmApp.Common.targets" TargetPath="Sdk" />
Expand Down
3 changes: 2 additions & 1 deletion src/mono/nuget/Microsoft.NET.Runtime.WebAssembly.Sdk/Sdk/Sdk.targets.in
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Expand Up @@ -13,5 +13,6 @@
</PropertyGroup>

<Import Project="$(MSBuildThisFileDirectory)\BrowserWasmApp.props" />
<Import Project="$(MSBuildThisFileDirectory)\BrowserWasmApp.targets" />
<Import Project="$(MSBuildThisFileDirectory)\BrowserWasmApp.targets" Condition="'$(UseMonoRuntime)' != 'false'" />
<Import Project="$(MSBuildThisFileDirectory)\BrowserWasmApp.CoreCLR.targets" Condition="'$(UseMonoRuntime)' == 'false'" />
</Project>
9 changes: 9 additions & 0 deletions ...ono/nuget/Microsoft.NET.Workload.Mono.Toolchain.Current.Manifest/WorkloadManifest.json.in
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Expand Up @@ -15,6 +15,15 @@
"extends": [ "microsoft-net-runtime-mono-tooling", "microsoft-net-sdk-emscripten" ],
"platforms": [ "win-x64", "win-arm64", "linux-x64", "linux-arm64", "linux-musl-x64", "linux-musl-arm64", "osx-x64", "osx-arm64" ]
},
"wasm-tools-coreclr": {
"description": ".NET WebAssembly build tools (CoreCLR) for ${NetVersion}.0",
"packs": [
"Microsoft.NET.Runtime.WebAssembly.Sdk.${NetVersion}",
"Microsoft.NET.Sdk.WebAssembly.Pack.${NetVersion}"
],

@akoeplinger akoeplinger Jul 6, 2026 •
edited
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should probably add the coreclr browser-wasm runtime pack here
(and as you know this will need to actually be done in the sdk repo as well)

"extends": [ "microsoft-net-sdk-emscripten" ],
"platforms": [ "win-x64", "win-arm64", "linux-x64", "linux-arm64", "linux-musl-x64", "linux-musl-arm64", "osx-x64", "osx-arm64" ]
},
"wasm-experimental": {
"description": ".NET WebAssembly experimental tooling for ${NetVersion}.0",
"packs": [
Expand Down
12 changes: 10 additions & 2 deletions .../nuget/Microsoft.NET.Workload.Mono.Toolchain.Current.Manifest/WorkloadManifest.targets.in
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Expand Up @@ -153,7 +153,7 @@

<!-- start of TFM specific logic, make sure every node has a TargetsCurrent/TargetsNet* condition -->

<Import Condition="'$(TargetsCurrent)' == 'true' and '$(RunAOTCompilation)' == 'true' and ('$(UsingBrowserRuntimeWorkload)' == 'true' or '$(UsingMobileWorkload)' == 'true' or '$(UsingWasiRuntimeWorkload)' == 'true')" Project="Sdk.props" Sdk="Microsoft.NET.Runtime.MonoAOTCompiler.Task.${NetVersion}" />
<Import Condition="'$(TargetsCurrent)' == 'true' and '$(RunAOTCompilation)' == 'true' and '$(UseMonoRuntime)' != 'false' and ('$(UsingBrowserRuntimeWorkload)' == 'true' or '$(UsingMobileWorkload)' == 'true' or '$(UsingWasiRuntimeWorkload)' == 'true')" Project="Sdk.props" Sdk="Microsoft.NET.Runtime.MonoAOTCompiler.Task.${NetVersion}" />

<ImportGroup Condition="'$(TargetsCurrent)' == 'true' and ('$(TargetPlatformIdentifier)' == 'android' or '$(_IsAndroidLibraryMode)' == 'true')">
<Import Project="Sdk.props" Sdk="Microsoft.NET.Runtime.MonoTargets.Sdk.${NetVersion}" />
Expand Down Expand Up @@ -204,14 +204,22 @@
<Import Project="Sdk.props" Sdk="Microsoft.NETCore.App.Runtime.AOT.Cross.${NetVersion}.tvossimulator-x64" />
</ImportGroup>

<ImportGroup Condition="'$(TargetsCurrent)' == 'true' and '$(RuntimeIdentifier)' == 'browser-wasm' and '$(UsingBrowserRuntimeWorkload)' == 'true'">
<ImportGroup Condition="'$(TargetsCurrent)' == 'true' and '$(RuntimeIdentifier)' == 'browser-wasm' and '$(UsingBrowserRuntimeWorkload)' == 'true' and '$(UseMonoRuntime)' != 'false'">
<Import Project="Sdk.props" Sdk="Microsoft.NET.Runtime.MonoTargets.Sdk.${NetVersion}" />
<Import Project="Sdk.props" Sdk="Microsoft.NET.Runtime.WebAssembly.Sdk.${NetVersion}" />
<Import Project="Sdk.targets" Sdk="Microsoft.NET.Runtime.WebAssembly.Sdk.${NetVersion}" />
<Import Project="Sdk.props" Sdk="Microsoft.NETCore.App.Runtime.AOT.Cross.${NetVersion}.browser-wasm" />
<Import Project="Sdk.targets" Sdk="Microsoft.NET.Runtime.MonoTargets.Sdk.${NetVersion}" />
</ImportGroup>

<!-- CoreCLR browser-wasm: only needs the WebAssembly.Sdk (build targets + emscripten).
No MonoTargets.Sdk, no MonoAOTCompiler, no AOT.Cross pack — the SDK resolves
the CoreCLR runtime pack and crossgen2 via its own KnownRuntimePack/KnownCrossgen2Pack. -->
<ImportGroup Condition="'$(TargetsCurrent)' == 'true' and '$(RuntimeIdentifier)' == 'browser-wasm' and '$(UsingBrowserRuntimeWorkload)' == 'true' and '$(UseMonoRuntime)' == 'false'">
<Import Project="Sdk.props" Sdk="Microsoft.NET.Runtime.WebAssembly.Sdk.${NetVersion}" />
<Import Project="Sdk.targets" Sdk="Microsoft.NET.Runtime.WebAssembly.Sdk.${NetVersion}" />
</ImportGroup>

<ImportGroup Condition="'$(TargetsCurrent)' == 'true' and '$(RuntimeIdentifier)' == 'wasi-wasm' and '$(UsingWasiRuntimeWorkload)' == 'true'">
<Import Project="Sdk.props" Sdk="Microsoft.NET.Runtime.MonoTargets.Sdk.${NetVersion}" />
<Import Project="Sdk.props" Sdk="Microsoft.NET.Runtime.WebAssembly.Wasi.Sdk.${NetVersion}" />
Expand Down
3 changes: 1 addition & 2 deletions src/mono/wasm/Wasm.Build.Tests/PInvokeTableGeneratorTests.cs
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Expand Up @@ -334,7 +334,7 @@ private async Task EnsureWasmAbiRulesAreFollowed(Configuration config, bool aot)
// FIXME: Not possible in in-process mode for some reason, even with verbosity at "diagnostic"
// Assert.Contains("Adding pinvoke signature FD for method 'Test.", output);

string pinvokeTableFileName = IsCoreClrRuntime ? "pinvoke-table.cpp" : "pinvoke-table.h";
string pinvokeTableFileName = IsCoreClrRuntime ? "callhelpers-pinvoke.cpp" : "pinvoke-table.h";
string pinvokeTable = File.ReadAllText(Path.Combine(objDir, pinvokeTableFileName));
// Verify that the invoke is in the pinvoke table. Under various circumstances we will silently skip it,
// for example if the module isn't found
Expand Down Expand Up @@ -367,7 +367,6 @@ public async Task EnsureWasmAbiRulesAreFollowedInAOT(Configuration config, bool

[Theory]
[BuildAndRun(aot: false)]
[TestCategory("native-mono")] // coreclr ActiveIssue: https://github.com/dotnet/runtime/issues/120897
public async Task EnsureWasmAbiRulesAreFollowedInInterpreter(Configuration config, bool aot) =>
await EnsureWasmAbiRulesAreFollowed(config, aot);

Expand Down
30 changes: 27 additions & 3 deletions src/tasks/WasmAppBuilder/coreclr/InterpToNativeGenerator.cs
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Expand Up @@ -63,6 +63,15 @@ private static void Emit(StreamWriter w, IEnumerable<string> cookies)
var signatures = cookies.OrderBy(c => c).Distinct().ToArray();
Array.Sort(signatures, StringComparer.Ordinal);

// Collect unique struct return sizes so we can emit typedefs
var structReturnSizes = new SortedSet<int>();
foreach (var sig in signatures)
{
var toks = SignatureMapper.ParseSignatureTokens(sig);
if (toks[0][0] == 'S' && toks[0].Length > 1)
structReturnSizes.Add(int.Parse(toks[0].Substring(1)));
}

w.Write(
"""
// Licensed to the .NET Foundation under one or more agreements.
Expand All @@ -85,6 +94,17 @@ private static void Emit(StreamWriter w, IEnumerable<string> cookies)
#define ARG_F32(i) (*(float*)ARG_ADDR(i))
#define ARG_F64(i) (*(double*)ARG_ADDR(i))

""");

// Emit typedefs for struct return types so emcc generates the correct sret ABI
foreach (var size in structReturnSizes)
{
w.WriteLine($"typedef struct {{ char d[{size}]; }} wasm_ret_S{size};");
}

w.Write(
"""

namespace
{
""");
Expand All @@ -104,7 +124,6 @@ private static void Emit(StreamWriter w, IEnumerable<string> cookies)
tokens.RemoveAt(tokens.Count - 1);
}
var args = Args(tokens);
var portabilityAssert = returnToken[0] == 'S' ? "PORTABILITY_ASSERT(\"Indirect struct return is not yet implemented.\");\n " : "";

var portableEntryPointComma = args.Count > 0 ? ", " : "";
var portableEntrypointDeclaration = isPortableEntryPointCall ? portableEntryPointComma + "PCODE" : "";
Expand All @@ -118,7 +137,7 @@ private static void Emit(StreamWriter w, IEnumerable<string> cookies)
{{(isPortableEntryPointCall ? "NOINLINE " : "")}}static void {{CallFuncName(args, SignatureMapper.TokenToNameType(returnToken), isPortableEntryPointCall)}}(PCODE {{(isPortableEntryPointCall ? "pPortableEntryPoint" : "pcode")}}, int8_t* pArgs, int8_t* pRet)
{{{(isPortableEntryPointCall ? "\n alignas(16) int framePointer = TERMINATE_R2R_STACK_WALK;" : "")}}
{{result.nativeType}} (*fptr)({{portableEntrypointStackDeclaration}}{{string.Join(", ", args.Select(static t => SignatureMapper.TokenToNativeType(t)))}}{{portableEntrypointDeclaration}}) = {{portableEntrypointPointerRD}}({{result.nativeType}} ({{portableEntrypointPointerRD}}*)({{portableEntrypointStackDeclaration}}{{string.Join(", ", args.Select(static t => SignatureMapper.TokenToNativeType(t)))}}{{portableEntrypointDeclaration}})){{(isPortableEntryPointCall ? "(pPortableEntryPoint)" : "pcode")}};
{{portabilityAssert}}{{(result.isVoid ? "" : "*" + "((" + result.nativeType + "*)pRet) = ")}}(*fptr)({{portableEntrypointStackParam}}{{string.Join(", ", ArgsWithSlotOffsets(args))}}{{portableEntrypointParam}});
{{(result.isVoid ? "" : "*" + "((" + result.nativeType + "*)pRet) = ")}}(*fptr)({{portableEntrypointStackParam}}{{string.Join(", ", ArgsWithSlotOffsets(args))}}{{portableEntrypointParam}});
}

""");
Expand Down Expand Up @@ -169,7 +188,12 @@ static List<string> ArgsWithSlotOffsets(List<string> args)
}

static (bool isVoid, string nativeType) Result(string returnToken)
=> new(returnToken == "v", SignatureMapper.TokenToNativeType(returnToken));
{
// For struct returns, use the typedef so emcc generates the correct sret ABI
if (returnToken[0] == 'S' && returnToken.Length > 1)
return (false, $"wasm_ret_{returnToken}");
return new(returnToken == "v", SignatureMapper.TokenToNativeType(returnToken));
}

static bool IsPortableEntryPointCall(List<string> tokens)
{
Expand Down