Port runtime PR dotnet/runtime#133111 R2R changes to SDK Crossgen tasks by maraf · Pull Request #56395 · dotnet/sdk

maraf · 2026-09-24T15:43:58Z

Why

dotnet/runtime's src/tasks/Crossgen2Tasks is a simplified fork of the SDK's shared Crossgen2/ReadyToRun task implementation. Runtime PR dotnet/runtime#133111 ("Use SDK pipeline for WebAssembly framework R2R") made changes to the shared task logic that were never migrated back into this SDK repo. This PR ports the task-and-target portions that apply to the SDK, excluding runtime-only WebCIL and runtime-pack policy.

What changed

Microsoft.NET.CrossGen.targets: _CreateR2RImages now tracks @(CrossgenTool), @(Crossgen2Tool), and @(_ReadyToRunCompilerInputs) as incremental inputs, so R2R images are recompiled when the compiler or its dependencies change. Both R2R compiler invocations also forward the runtime-private $(_PublishReadyToRunCrossgen2ExtraArgs) property alongside the existing public arguments.
PrepareForReadyToRunCompilation.cs: the R2R output-path helper now supports WebAssembly output. Separately compiled WASM images and composite component stubs use the .wasm paths emitted by Crossgen2, and a composite owner is published as <entry>.r2r.wasm.
Existing SDK-specific Mach-O behavior is preserved: separately compiled images use intermediate .o output linked into a published .dylib, while Mach-O composite components retain their managed assembly identity and do not receive native-link metadata.

Testing

Added focused PrepareForReadyToRunCompilation unit coverage for:

WASM output and publish paths for separately compiled images
WASM composite owner and component-stub paths
Mach-O native-link metadata for separately compiled images
Unchanged Mach-O composite component paths and metadata

Local validation:

Full Debug repository build completed successfully with 0 warnings and 0 errors.
Created and published a Blazor WebAssembly sample with the built 11.0.100-dev SDK, UseMonoRuntime=false, and PublishReadyToRun=true.
The captured publish binlog confirms the locally built Microsoft.NET.Build.Tasks.dll ran PrepareForReadyToRunCompilation and produced 37 .wasm paths in both _ReadyToRunCompileList and _ReadyToRunFilesToPublish.

Note

This PR description was generated with the assistance of GitHub Copilot.

Bring the SDK's shared Crossgen2/ReadyToRun task implementation in sync with the equivalent runtime-side changes from dotnet/runtime PR #133111 ("Use SDK pipeline for WebAssembly framework R2R"): - Track CrossgenTool, Crossgen2Tool, and the new @(_ReadyToRunCompilerInputs) item as incremental inputs to _CreateR2RImages, so R2R images are recompiled when the compiler or its dependencies change. - Forward the runtime-private $(_PublishReadyToRunCrossgen2ExtraArgs) property alongside the existing public extra-args property on both R2R compiler invocations. - Extend R2R output-path calculation to support WebAssembly output (.wasm), which Crossgen2 now emits directly, while preserving the existing Mach-O intermediate (.o) to final (.dylib) linking behavior for assemblies that are compiled separately. Composite component assemblies keep their original publish identity (no container-format extension rewriting or native-link metadata), matching pre-existing SDK behavior; only images that are compiled separately go through the container-aware output-path helper. Added focused regression tests covering WASM output/publish paths, preserved Mach-O native-link metadata for separately compiled images, unaffected composite component paths, and the new target-level incremental input/argument wiring. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

azure-pipelines · 2026-09-24T15:44:15Z

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lewing · 2026-09-24T21:59:51Z

dotnet/runtime#134618 enables PublishReadyToRunComposite for CoreCLR browser-wasm and depends on the composite owner path this PR introduces: with Crossgen2ContainerFormat=wasm, the owner must be compiled and published as <entry>.r2r.wasm. Crossgen2 records that exact name in each component stub, and the browser loader identifies and probes the owner by it. On current SDK main the owner would come out as <entry>.r2r.dll, so composite browser publishing only works through runtime's Crossgen2Tasks override today.

The added tests cover separately compiled wasm images and Mach-O composite components, but not the wasm composite owner. Could you add a case such as composite: true with "wasm" asserting that the owner's OutputR2RImage, ItemSpec, and RelativePath end in <entry>.r2r.wasm with no RequiresNativeLink, and that component images keep their original identity? That would keep this contract from regressing.

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This comment was generated with GitHub Copilot assistance.

maraf · 2026-09-25T12:12:43Z

@copilot apply feedback #56395 (comment)

Co-authored-by: maraf <10020471+maraf@users.noreply.github.com>

Copilot · 2026-09-25T12:24:56Z

[!WARNING]
Threat Detection Engine Failure — The analysis engine could not complete. This is a tooling failure, not a security finding.
...

Fixed in 37f4fbc. The XML assertions now handle nullable values safely and report missing required attributes clearly; the focused test passes.

@copilot apply feedback #56395 (comment)

Applied the linked build-feedback fix in 37f4fbc. The focused ReadyToRun task test now passes.

Preserve forward slashes from RelativePath metadata in cross-platform assertions and verify the composite WASM owner is published without native linking. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

lewing

The wasm composite owner test added in 0ad552b covers my earlier comment, thanks. One remaining question inline about behavior differing from dotnet/runtime#133111.

Note

This review was generated with GitHub Copilot assistance.

Apply container-aware output naming to all WebAssembly inputs so composite component publish items match the .wasm stubs emitted by Crossgen2, while preserving SDK-specific Mach-O behavior. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

maraf · 2026-09-29T08:19:01Z

Keep the task tests focused on unit behavior and stop copying the shipping targets file into the test output. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot

Copilot review overview

🟡 Changes recommended

The incremental target behavior lacks an automated MSBuild-level regression test.

Review effort: Balanced
Findings: 1

Open (1)

Add MSBuild regression test for incremental R2R invalidation · New

What changed in this PR

Ports WebAssembly ReadyToRun behavior from the runtime fork into the SDK’s shared Crossgen pipeline.

Changes:

Adds WASM output-path handling while preserving Mach-O behavior.
Tracks compiler inputs for incremental R2R builds and forwards private compiler arguments.
Adds focused task-level path and metadata tests.

File	Description
`PrepareForReadyToRunCompilation.cs`	Computes WASM and Mach-O compiler/publish paths.
`Microsoft.NET.CrossGen.targets`	Adds incremental inputs and private Crossgen2 arguments.
`GivenAPrepareForReadyToRunCompilation.cs`	Tests WASM and Mach-O task outputs.

Copilot

Copilot review overview

🟡 Changes recommended

WASI composite output naming is incompatible with its consumer, and incremental invalidation lacks automated coverage.

Review effort: Balanced
Findings: 1 · 1

Open (2)

Use fixed composite-r2r.wasm name for WASI targets · New
Add MSBuild regression test for incremental R2R invalidation · New

Resolved since last review (1)

Add MSBuild regression test for incremental R2R invalidation

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

## Why CoreCLR WASI composite ReadyToRun currently names the composite owner image `composite-r2r.wasm`. `PrepareForReadyToRunCompilation` in Crossgen2Tasks forces that name whenever `Crossgen2Tool` TargetOS is `wasi`. The browser composite work in #134618 uses the task's default name instead: `<entry>.r2r.wasm`, the main assembly name with `.r2r.wasm`. This PR drops the TargetOS special case so WASI gets the same owner name as browser. It lands ahead of the dotnet/sdk#56395 port, so that PR doesn't carry the WASI rule into the SDK. The two delivery models stay different on purpose. Browser instantiates the composite at runtime through the JS loader. WASI composes it offline into the host with `wasm-merge`/`wasm-opt`. Only the naming contract changes. ## Design The composite's own file name, as written by crossgen2, is the single authority. It is also the owner name every component stub records. - **`PrepareForReadyToRunCompilation`:** the `wasi` branch is removed. A wasm composite owner is now `<entry>.r2r.wasm` on both targets. - **`WasiApp.CoreCLR.targets`:** the composite path now comes from the planned composite compilation, `@(_ReadyToRunCompileList)` with `CreateCompositeImage=true`, via `%(OutputR2RImage)`. The build errors unless there is exactly one composite compilation. Because the path isn't hardcoded, WASI keeps working with either SDK naming. - **`wasi_r2r_probe.hpp`:** the host reserves a 256-byte composite name buffer, zero-initialized, and exports its address and capacity (`wasi_r2r_composite_name_base`, `wasi_r2r_composite_name_cap`). The probe serves the composite only when the requested name matches the recorded name, and only if that name is non-empty. An uncomposed host therefore serves no composite. There is no wildcard matching and no name compiled into C++. - **`ComposeWasiReadyToRun`:** the composer reads the two new exports and checks that the name is non-empty, contains no NUL, and fits the buffer. Its shim now imports `webcil.memory` and includes an active data segment that writes `Path.GetFileName(CompositePath)`, NUL-terminated, into the host buffer. This is the same mechanism that already installs the payload. A prebuilt host, such as the runtime-test corerun, can therefore be composed with a composite of any name. - **Docs:** updated the WASI host composition section of `docs/design/mono/webcil.md` and `docs/workflow/building/coreclr/wasi-r2r.md`. ## Validation - `./build.sh clr+libs+host+packs -os wasi -arch wasm -c Release` finished with 0 warnings and 0 errors. - `./dotnet.sh publish src/mono/sample/wasi/console/Wasi.Console.Sample.csproj -c Release -p:TargetOS=wasi -p:TargetArchitecture=wasm -p:RuntimeFlavor=CoreCLR -p:PublishReadyToRun=true` succeeded. The composer logged `composite='Wasi.Console.Sample.r2r.wasm'`. - The published app ran under wasmtime with `DOTNET_ReadyToRunLogFile` set. It exited 0, and the log shows `Ready to Run initialized successfully` for System.Private.CoreLib, Wasi.Console.Sample, System.Runtime, System.Console, System.Threading and System.Runtime.InteropServices. - **Negative check:** I composed the same host with a copy of the composite renamed to `Wrong.r2r.wasm`. Startup then traps in `EEStartup` because CoreLib's owner composite isn't served. A name mismatch fails loudly rather than silently interpreting. - **Non-R2R publish** of the same sample: the app runs on the interpreter, and the log shows `Ready to Run header not found`. - **Not run:** browser `ReadyToRunTests`. The removed code only executed when TargetOS was `wasi`, and the browser naming path is unchanged. ## Interaction with #134813 This PR merges cleanly with #134813's head (checked with `git merge-tree`); it doesn't depend on #134813. The runtime-test harness in #134813 passes the same `composite-r2r.wasm` path to both crossgen2 and `WasiR2RComposer.proj`. The composer records that name in the shared corerun, so the harness needs no changes. I did not build or run the runtime tests with both PRs merged. ## Follow-up in dotnet/sdk#56395 - Remove the `wasi` TargetOS block from `CreateReadyToRunFileToPublish`. - Change `It_uses_the_fixed_wasm_path_for_a_wasi_composite_owner` to expect `<entry>.r2r.wasm`, the same as browser. > [!NOTE] > This pull request description was generated with assistance from GitHub Copilot. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

## Summary - Enable `PublishReadyToRunComposite` for CoreCLR browser-wasm when WebCIL is enabled. Composite is opt-in; the default per-assembly R2R mode is unchanged. - Publish the composite owner (`<entry>.r2r.wasm`, the name crossgen2 records in each component stub) as a static web asset with a `readyToRunComposite` trait, defined through `DefineStaticWebAssets`. - `GenerateWasmBootJson` routes the owner to `resources.coreAssembly` and flags it `isCompositeImage: true`. The loader keeps its `.wasm` virtual path and leaves it out of the TPA, and component stubs stay in the TPA. Owner identity comes from the flag, not the file name, so an ordinary library named `*.r2r` still loads as a managed assembly. - Route composite component stubs through `ConvertDllsToWebcil`, keep the linked R2R closure across repeated trimmed publishes, and prune stale per-app images and stubs. - Invalidate per-app R2R images when the composite mode or crossgen2 arguments change. Component stubs share the per-assembly `<name>.wasm` names, so without this, switching composite to per-assembly shipped stale stubs that failed at startup. - Composite needs ReadyToRun tasks that name the owner `<entry>.r2r.wasm`. The base SDK doesn't yet (dotnet/sdk#56395), so a composite publish with stock SDK tasks fails fast with an actionable error. Wasm.Build.Tests use the in-repo Crossgen2Tasks, which now also ship in the `BuildWasmApps` Helix payload. ## Validation On `main` as of 2026-09-29, including WebCIL wrapper v2 (#134312), WASI composite in the shared Crossgen2Tasks (#133265), and the browser R2R strip defaults (#134690): - Rebuilt the CoreCLR browser Release runtime pack (`clr+libs+host`) and the WebAssembly SDK pack. - `Wasm.Build.Tests.ReadyToRunTests`: 10/10 passed. This covers: - composite trimmed, untrimmed and native-relinked, run in Chrome - a repeated trimmed publish - a composite → per-assembly → composite switch - per-assembly publish, native relink and dev-loop build - composite without WebCIL (negative) - Negative checks: - With the composite mode removed from the invalidation stamp, the mode-switch assertion fails. - With stock SDK ReadyToRun tasks, composite publish hits the new error. - CI: `PublishRunAllPagesComposite` passed on Helix on Linux and Windows. The remaining failures matched known issues (#133953, #133373). Benchmark (`IndexOfMax<double>(3079)`, browser, earlier revision of this PR): composite R2R ran the SIMD path with a median of **4,040 ns/op**, vs. **1,013,940 ns/op** interpreted and **10,652,060 ns/op** with per-assembly R2R. Part of testing #134559. That issue's default per-assembly scenario is not changed by this PR. > [!NOTE] > This pull request description was generated with GitHub Copilot assistance. --------- Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

maraf self-assigned this Sep 24, 2026

maraf added Area-WasmSdk Area-ReadyToRun labels Sep 24, 2026

maraf added this to the 12.0-preview1 milestone Sep 24, 2026

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Copilot started work on behalf of maraf September 25, 2026 12:13 View session

Copilot AI and others added 3 commits September 25, 2026 12:23

Fix ReadyToRun test nullability

cba8513

Co-authored-by: maraf <10020471+maraf@users.noreply.github.com>

Preserve ReadyToRun target lookup behavior

f4d938e

Co-authored-by: maraf <10020471+maraf@users.noreply.github.com>

Improve ReadyToRun XML test diagnostics

37f4fbc

Co-authored-by: maraf <10020471+maraf@users.noreply.github.com>

Copilot finished work on behalf of maraf September 25, 2026 12:25

lewing reviewed Sep 27, 2026

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Comment thread src/Tasks/Microsoft.NET.Build.Tasks/PrepareForReadyToRunCompilation.cs Outdated

lewing mentioned this pull request Sep 28, 2026

Add CoreCLR WASM composite R2R microbenchmark lane dotnet/performance#5324

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Remove XML inspection test for CrossGen targets

981825e

Keep the task tests focused on unit behavior and stop copying the shipping targets file into the test output. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

maraf marked this pull request as ready for review September 29, 2026 08:23

maraf requested a review from a team as a code owner September 29, 2026 08:23

maraf requested review from jkoritzinsky and pavelsavara and a balanced review from Copilot September 29, 2026 08:23

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Comment thread src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.CrossGen.targets

maraf requested review from lewing and a balanced review from Copilot September 29, 2026 09:27

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Comment thread src/Tasks/Microsoft.NET.Build.Tasks/PrepareForReadyToRunCompilation.cs

Comment thread src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.CrossGen.targets

Fix WASI composite ReadyToRun output name

f4a0674

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[wasm][coreclr] Enable composite ReadyToRun publishing dotnet/runtime#134618

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[wasi] Use the <entry>.r2r.wasm composite owner name on WASI dotnet/runtime#134874

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lewing mentioned this pull request Oct 1, 2026

[wasm] Remove the in-repo Crossgen2Tasks shim for browser composite R2R once the SDK names wasm R2R outputs dotnet/runtime#135023

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Align WASI composite ReadyToRun naming

1d1452e

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maraf enabled auto-merge (squash) October 2, 2026 11:43

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maraf merged commit 8c2c860 into main Oct 2, 2026
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maraf deleted the maraf-compare-crossgen2-tasks branch October 2, 2026 16:15

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[main] Source code updates from dotnet/sdk dotnet/dotnet#9906

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Port runtime PR dotnet/runtime#133111 R2R changes to SDK Crossgen tasks - #56395

Port runtime PR dotnet/runtime#133111 R2R changes to SDK Crossgen tasks#56395
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