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  1. JDK
  2. JDK-8211518

C2 should optimize if diamonds that feed into Phis merging the same value

    Details

    • Type: Enhancement
    • Status: Open
    • Priority: P4
    • Resolution: Unresolved
    • Affects Version/s: 12
    • Fix Version/s: tbd
    • Component/s: hotspot
    • Labels:

      Description

      C2 should optimize the following code shape:

             If
            / \
         Proj Proj
           \ / [...]
            \ / /
            Region1
             |
             | x x y
              \ | | /
                Phi

      This optimization was added with JDK-8210215 for regions with 2 and 3 inputs but should be extended/replaced for the general case. See discussion in:
      http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2018-October/030834.html

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              • Assignee:
                Unassigned
                Reporter:
                thartmann Tobias Hartmann
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                Dates

                • Created:
                  Updated: