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  1. JDK
  2. JDK-8168318

PPC64: Use cmpldi instead of li/cmpld

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

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        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

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                • Assignee:
                  gromero Gustavo Romero
                  Reporter:
                  gromero Gustavo Romero
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