[SimplifyCFG] Support not in chain of comparisons. #156497
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dtcxzyw
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Sep 4, 2025
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sound nice find that the regression can be handled in sccp. |
dtcxzyw
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Sep 17, 2025
If we know x in R1, the range check `x in R2` can be relaxed into `x in Union(R2, Inverse(R1))`. The latter one may be more efficient if we can represent it with one icmp. Fixes regressions introduced by #156497. Proof for `(X & -Pow2) == C -> (X - C) < Pow2`: https://alive2.llvm.org/ce/z/HMgkuu Compile-time impact: https://llvm-compile-time-tracker.com/compare.php?from=ead4f3e271fdf6918aef2ede3a7134811147d276&to=bee3d902dd505cf9b11499ba4f230e4e8ae96b92&stat=instructions%3Au
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If we know x in R1, the range check `x in R2` can be relaxed into `x in Union(R2, Inverse(R1))`. The latter one may be more efficient if we can represent it with one icmp. Fixes regressions introduced by llvm/llvm-project#156497. Proof for `(X & -Pow2) == C -> (X - C) < Pow2`: https://alive2.llvm.org/ce/z/HMgkuu Compile-time impact: https://llvm-compile-time-tracker.com/compare.php?from=ead4f3e271fdf6918aef2ede3a7134811147d276&to=bee3d902dd505cf9b11499ba4f230e4e8ae96b92&stat=instructions%3Au
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Proof: https://alive2.llvm.org/ce/z/cpXuCb