Acquire coherent nightly WASM workloads

[lewing]

Summary

• add --wasm-workload-source to acquire the SDK-pinned wasm-tools closure and exact CoreCLR browser-WASM runtime/ref, WebAssembly SDK, host-RID Crossgen2, and ILLink packages
• carry coherent workload sources through performance CI and Helix while preserving Mono WASM and private runtime payload behavior
• validate cohort versions/completeness and document local nightly/VMR CoreCLR WASM R2R usage

Validation

• python3 -m pytest -q scripts/tests/test_wasm_coreclr_r2r.py (21 passed)
• clean SDK smoke: installed 11.0.100-preview.6.26351.102 and its exact WASM cohort from the exclusive dotnet11 feed, including osx-arm64 Crossgen2 and native WASM tooling
• Python compile checks and git diff --check

Stack

Depends on #5297. This draft targets lewing-wasm-coreclr-r2r-perf and should be reviewed/merged after the lower CoreCLR WASM R2R layer.

[Copilot]

🟡 Changes recommended

wasm_sdk_cohort detection in run_performance_job.py treats an empty workload source as enabled, which can skip payload setup and then fail inconsistently.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

This PR adds support for acquiring and using a coherent, SDK-pinned CoreCLR browser-WASM workload cohort (including wasm-tools closure and exact runtime/ref/Crossgen2/ILLink/WebAssembly SDK packs) and propagates that source through performance CI/Helix, with documentation for local usage.

Changes:

• Add --wasm-workload-source option and forward it into Helix work item execution for CoreCLR WASM ReadyToRun runs.
• Implement cohort resolution and installation logic based on the SDK’s BundledVersions.props, with validation for coherent versions and required packages.
• Plumb the new option through pipeline templates and document nightly/VMR CoreCLR WASM R2R usage.

File summaries

File	Description
scripts/tests/test_wasm_coreclr_r2r.py	Adds coverage for forwarding/command generation and cohort version/package validation behavior.
scripts/run_performance_job.py	Threads --wasm-workload-source through Helix setup and payload preparation for CoreCLR WASM R2R runs.
scripts/dotnet.py	Adds host-RID detection plus coherent WASM workload cohort derivation and installation from an exclusive source.
scripts/benchmarks_ci.py	Adds CLI validation and local installation step for coherent CoreCLR WASM workload sources.
eng/pipelines/templates/runtime-perf-job.yml	Introduces a wasmWorkloadSource parameter for runtime perf jobs and forwards it downstream.
eng/pipelines/templates/run-performance-job.yml	Passes --wasm-workload-source into run_performance_job.py when configured.
docs/benchmarking-workflow-dotnet-runtime.md	Documents how to run CoreCLR WASM ReadyToRun using a nightly/VMR SDK + coherent package source.
docs/benchmarkdotnet.md	Updates the table-of-contents entry naming for private runtime builds.

Review details

• Files reviewed: 8/8 changed files
• Comments generated: 1
• Review effort level: Lite

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[Copilot]

🟡 Changes recommended

There are a couple of correctness/usability issues in the updated docs/CLI error messaging that should be fixed before merge.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Review details

• Files reviewed: 8/8 changed files
• Comments generated: 2
• Review effort level: Lite

[Copilot]

🔵 Needs a closer look

There are a couple of correctness/documentation issues (empty workload source handling and a duplicate TOC entry) that should be fixed before merging.

Review details

Suppressed comments (3)

docs/benchmarkdotnet.md:31

• The Table of Contents lists “Private Runtime Builds” twice (two bullets with the same #private-runtime-builds anchor), which makes the ToC confusing and adds a duplicate link.

    - [Running In Process](#running-in-process)
    - [CoreRun](#corerun)
    - [dotnet cli](#dotnet-cli)
    - [Private Runtime Builds](#private-runtime-builds)
    - [Private CoreRT Build](#private-corert-build)

scripts/dotnet.py:278

• This error message is inaccurate: the code allows omitting --dotnet-versions (sdk_versions can be empty) and resolves the SDK from dotnet --version. The message should only reject multiple SDK versions.

    if len(sdk_versions) > 1:
        raise ValueError(
            '--wasm-workload-source requires exactly one SDK version')

scripts/run_performance_job.py:987

• wasm_sdk_cohort becomes True when --wasm-workload-source is an empty string, which then skips the wasm_coreclr payload build and leaves dotnet_path unset later. Treat empty/whitespace values the same as “not provided”.

    wasm_sdk_cohort = (
        wasm_coreclr
        and args.r2r_run_type == "r2r"
        and args.wasm_workload_source is not None)

• Files reviewed: 8/8 changed files
• Comments generated: 0 new
• Review effort level: Lite