[llvm] [VectorCombine] Fix duplicate freeze scheduling for shared indexes (PR #213461)

[Aditya prakash jha via llvm-commits]

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AdityaOP007 wrote:

@ParkHanbum ,I've updated the regression test based on the reduced reproducer from llvm-autoreduce#255 so it now exercises the failing path. I also removed the unrelated changes to keep this PR focused. Let me know if anything else needs to be adjusted.

https://github.com/llvm/llvm-project/pull/213461