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  1. JDK
  2. JDK-8287697

Limit auto vectorization to 32-byte vector on Cascade Lake

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Details

    • Enhancement
    • Resolution: Fixed
    • P4
    • 19
    • 19
    • hotspot
    • b26
    • x86

    Description

      ~20% regression in SPECjvm2008 mpegaudio sub benchmark is observed on Cascade Lake with Default vs -XX:UseAVX=2.
      The performance of all the other non-startup sub benchmarks of SPECjvm2008 is within +/- 5%.
      The performance regression is due to auto-vectorization of small loops.
      We don’t have AVX3Threshold consideration in auto-vectorization.
      The performance regression in mpegaudio can be recovered by limiting auto-vectorization to 32-byte vectors.

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          relates to

          Bug - A problem which impairs or prevents the functions of the product. JDK-8287980 Build is broken due to SuperWordMaxVectorSize when C2 is disabled after JDK-8287697

          • P2 - Crashes, loss of data, severe memory leak.
          • Resolved

          Enhancement - null JDK-8311911 C2 Superword does not honor AVX3Threshold

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

          Enhancement - null JDK-8304301 Remove the global option SuperWordMaxVectorSize

          • P4 - Minor loss of function, or other problem where easy workaround is present.
          • Resolved
          links to

          Commit Commit openjdk/jdk/45f1b72a

          Review Review openjdk/jdk/8877

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              sviswanathan Sandhya Viswanathan
              sviswanathan Sandhya Viswanathan
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                Created:
                Updated:
                Resolved: