Cross-build browser WASM performance host tools

[lewing]

Summary

• add an opt-in CrossBuildHostTools property that defaults to false
• use it only for the host cross-component CoreCLR child build
• enable it for the browser CoreCLR performance build so the universal WASM JIT uses the existing Bionic sysroot
• leave the actual browser runtime build, normal browser builds, Mono, and mobile platforms unchanged

Validation

• evaluated ProjectToBuild with the repository SDK and confirmed the default host child remains CrossBuild=false
• confirmed the performance opt-in changes only the x64/Linux host child to CrossBuild=true, with ClrWasmJitSubset=true and CLR_CROSS_COMPONENTS_BUILD=1
• confirmed the top-level browser runtime build keeps CrossBuild unset
• confirmed Android and Mono continue to exclude the host Crossgen2 package
• confirmed the targeted clr.crossarchtools+clr.tools+packs graph includes the cross-built WASM JIT and host Crossgen2 pack
• parsed the modified YAML and ran git diff --check

Native GLIBC dependency inspection was not run locally because the development workspace is macOS without the Linux webassembly container. A runtime-wasm-perf run is required to verify the packaged JIT against Ubuntu 22.04 end to end.

Note

This pull request description was generated with GitHub Copilot.

[azure-pipelines]

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[Copilot]

🔵 Needs a closer look

This changes cross-build behavior in the build graph and performance pipeline; it needs end-to-end CI validation to confirm it packages and runs correctly across the intended Linux environments.

Pull request overview

Adds an opt-in MSBuild property to control whether the CoreCLR host cross-components child build is invoked with CrossBuild=true, and enables that opt-in for the browser WASM performance build job to allow cross-building the host toolset in that scenario.

Changes:

• Introduced CrossBuildHostTools (defaulting to false) to gate cross-building of the host cross-components build.
• Switched the CoreCLR cross-tools runtime.proj child invocation from CrossBuild=false to CrossBuild=$(CrossBuildHostTools).
• Enabled /p:CrossBuildHostTools=true for the browser_wasm CoreCLR perf build job.

File summaries

File	Description
eng/Subsets.props	Adds CrossBuildHostTools and uses it to control CrossBuild for the CoreCLR host cross-components child build.
eng/pipelines/performance/templates/perf-wasm-build-jobs.yml	Enables CrossBuildHostTools for the browser WASM CoreCLR perf build.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Lite

[lewing]

performance pr is dotnet/performance#5297 pipeline failure is https://dev.azure.com/dnceng-public/public/_build/results?buildId=1579905&view=results

[lewing]

/ba0g the sos failures are tracked in #133175

[lewing]

/ba-g the sos failures are tracked in #133175