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  1. JDK
  2. JDK-8222859

Improve object arraycopy to do single-loop

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    Details

    • Type: Enhancement
    • Status: Resolved
    • Priority: P4
    • Resolution: Withdrawn
    • Affects Version/s: 8-shenandoah, 11-shenandoah, 12, 13
    • Fix Version/s: tbd
    • Component/s: hotspot
    • Subcomponent:
      gc
    • CPU:
      generic
    • OS:
      generic

      Description

      Currently, object arraycopies requires up to 3 scans of the array:
      1. Pre-barrier scans the dst array for SATB
      2. Actual copy (using blit transfer)
      3. Post-barrier scans the dst array again to update any from-space refs to to-space

      This can be folded into a single loop which does the above per-element, and ensures to-space invariant before actually storing the object into the dst array. The latter would help other code that currently needs to deal with (temporary) from-space refs in arrays. See JDK-8222766.

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              Assignee:
              rkennke Roman Kennke
              Reporter:
              rkennke Roman Kennke
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                Created:
                Updated:
                Resolved: