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  1. JDK
  2. JDK-8209735

Disable avx512 by default

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    • Subcomponent:
    • Introduced In Version:
      9
    • Resolved In Build:
      b28
    • CPU:
      x86

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        Description

        I am working on JDK-8209594 (short branches distance too big when avx512 is used) and I found more issues with it and I need time to find all cases.

        Some instructions are totally wrong (copy-paste error) when register >=16 are used:
        http://hg.openjdk.java.net/jdk/jdk11/file/f729ca27cf9a/src/hotspot/cpu/x86/macroAssembler_x86.cpp#l4680
        http://hg.openjdk.java.net/jdk/jdk11/file/f729ca27cf9a/src/hotspot/cpu/x86/macroAssembler_x86.cpp#l4581

        Also some vector predicated in .ad file are wrong for the same issue:
        http://hg.openjdk.java.net/jdk/jdk11/file/f729ca27cf9a/src/hotspot/cpu/x86/x86.ad#l5647

        I am currently trying to instrument code to emulate situation when only xmm16-31 are used, as we discussed before, to find incorrect cases and I need time for that.

        At this later time I want to switch off avx512 in JDK 11.

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                Assignee:
                kvn Vladimir Kozlov
                Reporter:
                kvn Vladimir Kozlov
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                  Updated:
                  Resolved: