Add r2 r composite

[DrewScoggins]

No description provided.

[LoopedBard3]

Looks good, some merge conflicts that need to be fixed.

[Copilot]

Pull request overview

Adds a new runtime flavor to the performance infrastructure to run CoreCLR microbenchmarks using a Composite R2R setup with interpreter fallback, including payload staging and pipeline wiring.

Changes:

• Add coreclr_r2r_interpreter runtime type handling to build a Helix payload and pass the required BenchmarkDotNet arguments.
• Introduce a new payload builder helper to stage a runtime pack + crossgen2 tool layout for R2R compilation.
• Wire a new Azure Pipelines job matrix toggle/job and bump BenchmarkDotNet nightly.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
scripts/run_performance_job.py	Adds BDN arg selection and payload staging for coreclr_r2r_interpreter.
scripts/build_runtime_payload.py	Adds build_r2r_interpreter_payload() to extract runtime pack + crossgen2 into the expected layout.
eng/Versions.props	Updates BenchmarkDotNet nightly version.
eng/pipelines/templates/runtime-perf-job.yml	Adds build dependency and artifact download logic for the new runtime type.
eng/pipelines/runtime-perf-jobs.yml	Adds a new Viper microbenchmarks job toggle/matrix for coreclr_r2r_interpreter.

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[Copilot]

use_r2r_interpreter is assigned but never referenced later in run_performance_job, which makes the new code path harder to reason about and suggests a missing integration step. Either remove the variable entirely, or use it to drive whatever behavior difference is intended for the coreclr_r2r_interpreter runtime type (e.g., selecting a different dotnet install/payload logic).

Suggested change

	use_r2r_interpreter = False
	if args.runtime_type == "coreclr_r2r_interpreter":
	use_r2r_interpreter = True
	if args.runtime_type == "coreclr_r2r_interpreter":