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  1. JDK
  2. JDK-4659977

Allocate buffers for arrays at 8-byte aligned addresses

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    • gc
    • sparc
    • solaris_2.6

    Description


      I am not sure if native_interface is the correct subcategory for this issue.
      If not, please reassign it.

      As you know, for better performance, 8-byte aligned buffers are desired,
      especially when SIMD-style instructions like the VIS on UltraSPARC are
      used. The Get<PrimitiveType>ArrayElements functions seem to be able to
      copy arrays to native buffers starting from 8-byte aligned addresses all
      the time, which is good.

      It came to my notice that non-double arrays pinned by the JNI function
      GetPrimitiveArrayCritical are always starting from addresses which are
      not 8-byte aligned. In fact, they are always starting from either ...4
      or ...C. I hope that the VM can be somewhat modified to allocate arrays
      starting from 8-byte aligned addresses.

      A test case, TestArray.java, is attached to this report. The results
      I got are as follows:

      solarcell % run.csh
      java version "1.4.0"
      Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-b92)
      Java HotSpot(TM) Client VM (build 1.4.0-b92, mixed mode)
      ------ i = 0 ------
      bp = e243ee14, Get-isCopy = 0, Release-isCopy = 2
      sp = e243f2ec, Get-isCopy = 0, Release-isCopy = 2
      ip = e243fbc4, Get-isCopy = 0, Release-isCopy = 2
      fp = e2440c9c, Get-isCopy = 0, Release-isCopy = 2
      dp = e2441d78, Get-isCopy = 0, Release-isCopy = 2
      ------ i = 1 ------
      bp = e2443f9c, Get-isCopy = 0, Release-isCopy = 2
      sp = e24443ac, Get-isCopy = 0, Release-isCopy = 2
      ip = e2444bbc, Get-isCopy = 0, Release-isCopy = 2
      fp = e2445bcc, Get-isCopy = 0, Release-isCopy = 2
      dp = e2446be0, Get-isCopy = 0, Release-isCopy = 2
      ------ i = 2 ------
      bp = e2448d3c, Get-isCopy = 0, Release-isCopy = 2
      sp = e244914c, Get-isCopy = 0, Release-isCopy = 2
      ip = e244995c, Get-isCopy = 0, Release-isCopy = 2
      fp = e244a96c, Get-isCopy = 0, Release-isCopy = 2
      dp = e244b980, Get-isCopy = 0, Release-isCopy = 2
      ------ i = 3 ------
      bp = e244dadc, Get-isCopy = 0, Release-isCopy = 2
      sp = e244deec, Get-isCopy = 0, Release-isCopy = 2
      ip = e244e6fc, Get-isCopy = 0, Release-isCopy = 2
      fp = e244f70c, Get-isCopy = 0, Release-isCopy = 2
      dp = e2450720, Get-isCopy = 0, Release-isCopy = 2
      ------ i = 4 ------
      bp = e245287c, Get-isCopy = 0, Release-isCopy = 2
      sp = e2452c8c, Get-isCopy = 0, Release-isCopy = 2
      ip = e245349c, Get-isCopy = 0, Release-isCopy = 2
      fp = e24544ac, Get-isCopy = 0, Release-isCopy = 2
      dp = e24554c0, Get-isCopy = 0, Release-isCopy = 2

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              phh Paul Hohensee
              xuecheng James Cheng
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