[perf][wasm] Stage Crossgen2 pack for CoreCLR R2R benchmarks

[lewing]

Summary

Stage the matching locally built, non-symbol Microsoft.NETCore.App.Crossgen2 package in the BrowserWasmCoreCLR performance artifact under staging/built-nugets.

This enables isolated Helix machines to resolve the same-build Crossgen2 pack when per-application browser-WASM benchmarks publish with PublishReadyToRun=true. The CoreCLR performance build enables BuildHostTools, and the pack subset permits browser builds with that explicit opt-in to run Microsoft.NETCore.App.Crossgen2.Host.sfxproj. The package selection excludes *.symbols.nupkg and fails if no matching non-symbol package is available. These changes apply only to BrowserWasmCoreCLR; Mono artifact behavior is unchanged.

End-to-end runtime-wasm-perf validation depends on the companion dotnet/performance change currently at commit 17449e9826d0ecc224e92a3ad854796b0be41219.

Validation

• Parsed the changed XML and YAML build configuration.
• Ran git diff --check and commit checks.
• Simulated staging with matching non-symbol, symbols, and unrelated nupkgs; only the non-symbol Crossgen2 package was copied.
• Evaluated the MSBuild project graph and confirmed:
  • browser CoreCLR with BuildHostTools=true includes Microsoft.NETCore.App.Crossgen2.Host.sfxproj;
  • browser CoreCLR without the opt-in excludes it;
  • Android remains excluded even with BuildHostTools=true.

Note

This pull request was generated with the assistance of GitHub Copilot.

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[Copilot]

🟢 Approval recommended

The changes are narrowly scoped to the CoreCLR browser-wasm perf pipeline and the updated conditions/staging logic are consistent with existing TargetsMobile semantics for TargetOS=browser.

Pull request overview

This PR updates the WASM performance build to produce and stage the host Crossgen2 pack alongside the CoreCLR browser-wasm performance artifact, enabling downstream R2R publishing on isolated machines using same-build assets.

Changes:

• Allow building the Crossgen2 host pack when TargetOS=browser and BuildHostTools=true (even though browser sets TargetsMobile=true).
• Add an optional pipeline step to copy the non-symbol Microsoft.NETCore.App.Crossgen2.*.nupkg into the staged built-nugets feed and fail if none is present.
• Enable BuildHostTools=true for the CoreCLR browser-wasm perf build job and turn on Crossgen2 pack staging for its artifact.

File summaries

File	Description
eng/Subsets.props	Adjusts pack-building conditions so browser-wasm CoreCLR builds can produce the host Crossgen2 pack when opted in.
eng/pipelines/performance/templates/perf-wasm-prepare-artifacts-steps.yml	Adds an opt-in step to stage only non-symbol Crossgen2 nupkgs into the perf artifact’s local feed.
eng/pipelines/performance/templates/perf-wasm-build-jobs.yml	Opts the CoreCLR browser-wasm perf job into BuildHostTools and Crossgen2 pack staging.

Review details

• Files reviewed: 3/3 changed files
• Comments generated: 0
• Review effort level: Lite