Copilot instructions

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2applyTo: "src/coreclr/jit/**"
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5# RyuJIT (JIT compiler) — Folder-Specific Guidance
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7## Code Review Guidelines
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9- **Do not routinely request new targeted tests for pure refactors, mechanical cleanups, or other non-behavioral JIT codebase improvements.** JIT changes alter global codegen and are often validated by existing end-to-end suites and differential testing, so additional per-PR regression tests may not be needed for changes that do not affect observable behavior. However, targeted tests are appropriate and should be encouraged for bug fixes, changes with a clear repro, observable behavior changes, and previously untested edge cases that are not already covered by existing tests.
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