two: Avoid branch in computation of idx2 #469
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I haven't been able to find any changes in the benchmarks so far. The generated code looks better though. |
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I'm a bit surprised GHC doesn't undo this optimization. If the generated code looks better, go for it. |
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Yeah, GHC is pretty eager to generate a branch here. E.g. |
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We have index :: Hash -> Shift -> Int
index w s = fromIntegral $ unsafeShiftR w s .&. subkeyMaskSo I think another option would be to shift the |
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Yes, there are more low-level tweaks that can be applied here. #468 (comment) is related. |
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