[llvm] [InstCombine] signum: or (ashr X, BW-1), (lshr (-X), BW-1) --> scmp(X, 0) (PR #205365)

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AZero13 wrote:

> Please cite the specific real-world code where this pattern occurs.

Oh it definitely occurs in the real world... just that a previous pattern was covering a hyper-specific version of it (the most common case), but when I replace that fold with this one, it still works!

https://github.com/llvm/llvm-project/pull/205365