[browser][coreCLR] browserhost to load R2R#129634
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Pull request overview
This PR extends the WebAssembly build/publish pipeline to support ReadyToRun (R2R) “webcil-in-wasm” assemblies by staging prebuilt R2R .wasm images, emitting webcil payload/table sizing into the boot config, and updating the JS loader/host to instantiate webcil modules using those sizes (enabling streaming instantiation and avoiding runtime-side wasm parsing).
Changes:
- Add an MSBuild path to crossgen selected assemblies to R2R webcil-in-wasm and feed those artifacts into webcil conversion/staging.
- Emit
payloadSize(andtableSizefor R2R) into the boot config assets so the loader can instantiate without callinggetWebcilSize/ parsing wasm. - Update the JS loader/host surface and typings to pass these sizes through to
instantiateWebcilModule.
Reviewed changes
Copilot reviewed 15 out of 16 changed files in this pull request and generated 9 comments.
Show a summary per file
| File | Description |
|---|---|
| src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/GenerateWasmBootJson.cs | Plumbs webcil size metadata into boot config generation and passes it to asset transformation. |
| src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ConvertDllsToWebCil.cs | Adds optional staging of prebuilt R2R .wasm replacements and emits a WebcilSizes output by parsing wasm. |
| src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/BootJsonData.cs | Extends boot asset schema with tableSize/payloadSize fields. |
| src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/BootJsonBuilderHelper.cs | Writes payloadSize/tableSize onto boot assets during resources→assets transformation. |
| src/native/libs/Common/JavaScript/types/public-api.ts | Exposes tableSize/payloadSize on AssemblyAsset in public TS types. |
| src/native/libs/Common/JavaScript/types/internal.ts | Adds internal asset fields for tableSize/payloadSize. |
| src/native/libs/Common/JavaScript/types/ems-ambient.ts | Extends ambient emscripten symbol typing for wasm exports needed by R2R webcil imports. |
| src/native/libs/Common/JavaScript/loader/dotnet.d.ts | Updates loader .d.ts for AssemblyAsset to include tableSize/payloadSize. |
| src/native/libs/Common/JavaScript/loader/assets.ts | Passes tableSize/payloadSize to browser-host instantiateWebcilModule. |
| src/native/libs/Common/JavaScript/host/assets.ts | Reworks instantiateWebcilModule to allocate payload and instantiate webcil wasm (streaming when possible) using boot-config sizes. |
| src/mono/nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targets | Wires R2R candidates into ConvertDllsToWebcil, propagates WebcilSizes, and adds a _WasmCrossgenReadyToRunAssemblies target. |
| src/mono/browser/build/WasmApp.InTree.props | Defines in-tree crossgen2/jit/reference paths consumed by the new R2R target. |
| src/mono/sample/wasm/browser-R2R/Wasm.Browser.R2R.csproj | Adds a new sample that opts its app assembly into R2R cross-compilation. |
| src/mono/sample/wasm/browser-R2R/Program.cs | Sample app entrypoint. |
| src/mono/sample/wasm/browser-R2R/wwwroot/index.html | Sample web page host. |
| src/mono/sample/wasm/browser-R2R/wwwroot/main.js | Sample boot/run script using dotnet.js. |
This was referenced Jun 20, 2026
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| // Key by the logical assembly name (".dll"), not the produced ".wasm" file name: the boot | ||
| // config lists webcil assemblies under their logical ".dll" name, and GenerateWasmBootJson | ||
| // looks these sizes up by that name (resourceName). Using ".wasm" here would never match. | ||
| // Keying by ".dll" also avoids colliding with same-stem assets (e.g. a "X.pdb" never matches | ||
| // "X.dll"). | ||
| string fileName = Path.ChangeExtension(Path.GetFileName(webcilPath), ".dll"); | ||
| string key = string.IsNullOrEmpty(culture) ? fileName : culture + "/" + fileName; | ||
| var item = new TaskItem(key); |
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| export async function instantiateWebcilModule(webcilPromise: Promise<Response>, memory: WebAssembly.Memory, virtualPath: string, tableSize?: number, payloadSize?: number): Promise<void> { | ||
| // The boot config carries payloadSize for every webcil asset (and tableSize for R2R images), so | ||
| // the loader never buffers the bytes, parses the data section or calls getWebcilSize. Assets | ||
| // without a tableSize are plain (Webcil wrapper version 0) images. | ||
| if (typeof payloadSize !== "number" || payloadSize === 0) { | ||
| throw new Error(`Webcil asset '${virtualPath}' is missing payloadSize in the boot config.`); | ||
| } |
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| <ConvertDllsToWebcil | ||
| Candidates="@(_WasmDllBuildCandidates)" | ||
| IntermediateOutputPath="$(_WasmBuildTmpWebcilPath)" | ||
| OutputPath="$(_WasmBuildWebcilPath)" | ||
| IsEnabled="$(_WasmEnableWebcil)" | ||
| WebcilVersion="$(_WasmWebcilVersion)" | ||
| R2RWebcilCandidates="@(WasmR2RWebcilCandidate)"> | ||
| <Output TaskParameter="FileWrites" ItemName="FileWrites" /> | ||
| <Output TaskParameter="FileWrites" ItemName="_WasmConvertedWebcilOutputs" /> | ||
| <Output TaskParameter="WebcilSizes" ItemName="_WasmWebcilSizes" /> |
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| /// <summary> | ||
| /// Payload/table sizes for each webcil (keyed by the logical assembly name, e.g. "App.dll"), | ||
| /// produced by ConvertDllsToWebcil. Emitted into the boot config so the runtime loader doesn't | ||
| /// parse the wasm or call getWebcilSize. | ||
| /// </summary> | ||
| public ITaskItem[] WebcilSizes { get; set; } |
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| /// <summary> | ||
| /// Payload/table sizes for each produced webcil, keyed by the logical assembly name as it | ||
| /// appears in the boot config: the file name (e.g. "System.Console.dll"), or | ||
| /// "{culture}/{name}.dll" for satellite assemblies so that same-named satellites in different | ||
| /// cultures don't collide. Lets the boot config carry the sizes so the runtime loader doesn't | ||
| /// buffer/parse the wasm. PayloadSize is set for every webcil; TableSize is non-zero only for | ||
| /// R2R images. | ||
| /// </summary> |
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| extern "C" UINT_PTR STDCALL GetCurrentIP(void) | ||
| { | ||
| PORTABILITY_ASSERT("GetCurrentIP is not implemented on wasm"); | ||
| // WASM-TODO: Implement this function to return the current instruction pointer in the interpreter. | ||
| return 0; |
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| int want = dataLength >= 8 ? 8 : 4; | ||
| byte[] sizes = new byte[8]; | ||
| if (!TryFill(fs, sizes, want)) | ||
| { | ||
| failureReason = "data segment 0 was truncated before the sizes could be read"; | ||
| return false; | ||
| } | ||
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| payloadSize = (int)ReadUInt32LE(sizes, 0); | ||
| tableSize = want == 8 ? (int)ReadUInt32LE(sizes, 4) : 0; | ||
| return true; |
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| function displayMeaning(meaning) { | ||
| console.log(`Meaning of life is ${meaning}`); | ||
| document.getElementById("out").innerHTML = `${meaning}`; | ||
| } | ||
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| function delay(ms) { | ||
| return new Promise(resolve => setTimeout(resolve, ms)); | ||
| } | ||
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| try { | ||
| const { setModuleImports, getAssemblyExports } = await dotnet | ||
| .withConfig({ appendElementOnExit: true, exitOnUnhandledError: true, forwardConsole: true, logExitCode: true }) | ||
| .withDiagnosticTracing(true) | ||
| .withApplicationArguments("--meaning", "42") | ||
| .create(); |
3 tasks
…thods CallDescrWorkerInternal (the wasm reflection/CallDescr invoke path) resolved the interpreter byte code via MethodDesc::GetInterpreterCode() and, after a DoPrestub retry, passed the pointer straight to ExecuteInterpretedMethodWithArgs. When the target method has no interpreter byte code because it was compiled to native (R2R) code, GetInterpreterCode() returns NULL. On wasm a NULL pointer reads zeroed low linear memory instead of faulting, so the interpreter dispatched the NULL byte code as INTOP_INVALID and aborted with Unimplemented or invalid interpreter opcode plus a secondary stackwalk assert. Add the InvokeManagedMethod fallback (the interpreter->R2R thunk) when there is no interpreter code, mirroring the existing pattern in ExecuteInterpretedMethodWithArgs_PortableEntryPoint_Complex and the CALL_INTERP_METHOD path in InterpExecMethod. Also harden the sibling entry points: ExecuteInterpretedMethodFromUnmanaged now takes the same fallback, and ExecuteInterpretedMethodWithArgs asserts a non-NULL targetIp so future misuse fails loudly at the point of error.
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| using System; | ||
| using System.Runtime.InteropServices.JavaScript; | ||
| using System.Runtime.InteropServices; | ||
| using System.Threading.Tasks; |
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| /// </summary> | ||
| [Output] | ||
| public ITaskItem[] WebcilSizes { get; set; } |
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