C2: apply KnownBits and unsigned bounds to And / Or operations

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    • Type: Enhancement
    • Resolution: Fixed
    • Priority: P4
    • 27
    • Affects Version/s: 26
    • Component/s: hotspot
    • b03

      After JDK-8315066, we should apply especially the KnownBits to And / Or nodes.

      Feel free to file more RFE's for the other ideas, if you only want to do KnownBits for And / Or.

      This would help us generate more KnownBit patterns in the first place, and then it also helps us verify KnownBit types by extracting bits.

      Without, it is a bit hard to generate good tests for optimizations that already use KnownBits.

      A somewhat related concern: we should have a good way to restrict values on the unsigned range. Maybe some unsigned min/max node, or at least cast after unsigned comparison? Maybe that already works, would just be nice to know so we can use it in verification. Also related to JDK-8359412.

      It would have been really helpful to already have in JDK-8365205, and will be helpful in any further KnownBits optimizations.

            Assignee:
            Quan Anh Mai
            Reporter:
            Emanuel Peter
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              Updated:
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