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  1. JDK
  2. JDK-8001436

C2: Implement bitwise constant propagation

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    Details

    • Type: Enhancement
    • Status: Open
    • Priority: P4
    • Resolution: Unresolved
    • Affects Version/s: 14
    • Fix Version/s: tbd
    • Component/s: hotspot
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      Description

      In type.[ch]pp, to TypeInt and TypeLong, add bitwise constant information.

      Specifically, in addition to arithmetic upper and lower bounds _hi and _lo, add bitwise upper and lower bounds, _up and _dn.

      Push this information through TypePtr offsets, to track alignment information.

      Use this information to help decide if ALU operations can be strength reduced.

      The bit equations can be derived with some thought. A working Java prototype is attached (creation date is 4/18/2007, by jrose).

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              Assignee:
              Unassigned Unassigned
              Reporter:
              jrose John Rose
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                Created:
                Updated: