[jdk17] RFR: 8269825: [TESTBUG] Missing testing for x86 KNL platforms

[Jatin Bhateja]

On Fri, 2 Jul 2021 20:37:24 GMT, Dean Long <dlong at openjdk.org> wrote:

>> Knights family of X86 Intel CPU (KNL) does not support some of avx512 features (AVX512VL/BW) and have other restrictions. We may not have such kind of machines in our testing environment and may miss bugs as JBS history shows (look recent fixes for KNL).
>> On other hand we have some Windows VM instances which seem emulate KNL configuration and limit avx512 instructions on CPU which supports full set. Recent bug JDK-8269775 shows such example.
>> I suggest to add -XX:+UseKNLSetting x86 diagnostic flag to emulate KNL settings in HotSpot VM to test such configuration.
>
> Marked as reviewed by dlong (Reviewer).

Hi @dean-long , @vnkozlov ,
Since the idea is to test KNL settings on any latest X86 Server platform we should also turn off following options.

 if (is_intel()) { // Intel cpus specific settings
    if (is_knights_family()) {
      _features &= ~CPU_VZEROUPPER;
      _features &= ~CPU_AVX512BW;
      _features &= ~CPU_AVX512VL;
+      _features &= ~CPU_AVX512DQ;
+      _features &= ~CPU_AVX512_VNNI;
+      _features &= ~CPU_AVX512_VAES;
+      _features &= ~CPU_AVX512_VPOPCNTDQ;
+      _features &= ~CPU_AVX512_VPCLMULQDQ;
+      _features &= ~CPU_AVX512_VBMI;
+      _features &= ~CPU_AVX512_VBMI2;
    }
  }

-------------

PR: https://git.openjdk.java.net/jdk17/pull/205