[llvm] [LAA] Avoid duplicate runtime-check group members (PR #226829)

[Dávid Bolvanský via llvm-commits]

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davidbolvansky wrote:

Yes, that is the intended functional effect: duplicate read/write entries previously consumed comparison-budget iterations and could hit this break early. Keying  by  removes those duplicate entries before grouping, so only actual members count toward the threshold. The updated analysis expectations exercise the resulting group membership/output.

https://github.com/llvm/llvm-project/pull/226829