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  1. JDK
  2. JDK-8287697

Limit auto vectorization to 32-byte vector on Cascade Lake

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    • x86

      ~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.

            sviswanathan Sandhya Viswanathan
            sviswanathan Sandhya Viswanathan
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