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  1. JDK
  2. JDK-8149758

Small arraycopy of non-constant length is slower than individual load/stores

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      JDK-6912521 added support for exploding arraycopy into the series of individual loads and stores. However, that apparently only works when copy size is statically known. In some interesting cases, it does not, see e.g. JDK-8148937, that uses String APIs doing the arraycopies for trivial delimiters, and that apparently penalizes performance.

      Benchmark + performance data:
       http://cr.openjdk.java.net/~shade/8149758/ArrayCopyDynamic.java

      Runnable JAR:
       http://cr.openjdk.java.net/~shade/8149758/benchmarks.jar

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          relates to

          Enhancement - null JDK-8150730 Improve performance of x86_64 arraycopy stubs

          • P3 - Major loss of function.
          • Open

          Enhancement - null JDK-8148937 (str) Adapt StringJoiner for Compact Strings

          • P3 - Major loss of function.
          • Resolved

          Enhancement - null JDK-6912521 System.arraycopy works slower than the simple loop for little lengths

          • P5 - Cosmetic problem like misspelt words or misaligned text.
          • Resolved

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              Unassigned Unassigned
              shade Aleksey Shipilev
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                Created:
                Updated: