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  1. JDK
  2. JDK-8150313

aarch64: optimise array copy using SIMD instructions

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    Details

    • Type: Enhancement
    • Status: Resolved
    • Priority: P4
    • Resolution: Fixed
    • Affects Version/s: 9
    • Fix Version/s: 9
    • Component/s: hotspot
    • Labels:
      None
    • Subcomponent:
    • Resolved In Build:
      b112
    • CPU:
      aarch64
    • OS:
      linux

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        Description

        This uses SIMD ldp/stp Qx, Qy instructions instead of scalar ldp/stp instructions, thereby loading/storing 32 bytes at a time instead of 16.

        It also extends the small copy code to copy 0-96 instead of 0-80 (because 80 is not divisible by 32).

        This improves performance on some micro-arches and not on others so I have provided a -XX:+UseSIMDForMemoryOps switch which defaults to false (we could look at enabling this by default for micro-arches where we know SIMD is better).

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                Assignee:
                enevill Ed Nevill
                Reporter:
                enevill Ed Nevill
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                  Updated:
                  Resolved: