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  1. JDK
  2. JDK-8168318

PPC64: Use cmpldi instead of li/cmpld

    Details

    • Subcomponent:
    • Resolved In Build:
      b146
    • CPU:
      ppc
    • OS:
      linux

      Backports

        Description

        On profiling some specific Neo4j workloads, some cases where a sequence of load (li) and compare (cmpld) can be
        replaced by a single cmpldi instructions were identified. On replacing that sequence by a single instruction it's
        possible to reduce the path length so the program is shorter, and therefore is faster.

        Additionally, the 2 instruction sequence requires an additional register that with enough register pressure a
        spill would be needed to accommodate that approach.

        It's related to the discussion started here:
        http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2016-October/024664.html

          Activity

          Hide
          gromero Gustavo Romero added a comment -
          FC Extension Request

          Justification: This is a significant ppc64-only performance improvement
          Risk: Low. Does not affect any of the Oracle platforms in any way
          Proposed Integration Date: As soon as granted
          Remaining work: none

          Webrev: http://cr.openjdk.java.net/~gromero/8168318/01/
          Show
          gromero Gustavo Romero added a comment - FC Extension Request Justification: This is a significant ppc64-only performance improvement Risk: Low. Does not affect any of the Oracle platforms in any way Proposed Integration Date: As soon as granted Remaining work: none Webrev: http://cr.openjdk.java.net/~gromero/8168318/01/
          Show
          gromero Gustavo Romero added a comment - Review thread: http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2016-October/024771.html
          Hide
          kvn Vladimir Kozlov added a comment -
          Approved.
          Show
          kvn Vladimir Kozlov added a comment - Approved.
          Hide
          hgupdate HG Updates added a comment -
          URL: http://hg.openjdk.java.net/jdk9/hs/hotspot/rev/622d3fe587f2
          User: goetz
          Date: 2016-10-27 10:26:54 +0000
          Show
          hgupdate HG Updates added a comment - URL: http://hg.openjdk.java.net/jdk9/hs/hotspot/rev/622d3fe587f2 User: goetz Date: 2016-10-27 10:26:54 +0000
          Hide
          hgupdate HG Updates added a comment -
          URL: http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/622d3fe587f2
          User: lana
          Date: 2016-11-22 22:03:30 +0000
          Show
          hgupdate HG Updates added a comment - URL: http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/622d3fe587f2 User: lana Date: 2016-11-22 22:03:30 +0000

            People

            • Assignee:
              gromero Gustavo Romero
              Reporter:
              gromero Gustavo Romero
            • Votes:
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              Watchers:
              3 Start watching this issue

              Dates

              • Due:
                Created:
                Updated:
                Resolved: