RFR: 8287794: Reverse*VNode::Identity problem [v4]

[Xiaohong Gong]

On Thu, 28 Jul 2022 07:04:44 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> Thanks for updating the tests! I ran the test in our internal testing system,  and unfortunately, this case will fail with "-XX:UseSVE=0" as expected. The reason is actually like what I said above. So to fix this, could you please:
>> 
>> 1. Limit the whole test on aarch64 os systems by adding "`@requires vm.cpu.features ~= ".*simd.*"`" before the test. And limit the single IR test by adding "`applyIf={"UseSVE", ">0"}`" .
>> 
>> OR
>> 
>> 2. Fix the IR framework, to make "applyIf" and "applyIfCPUFeature" can co-work with each other.
>> 
>> WDYT?
>
> I am not clear, if UseSVE=0 then why does "sve" feature getting populated during VM initialization?
> Entire handling of applyIfCPUFeature* is based on white box CPU feature API which queries the feature list populated during VM initialization, we are not directly queries the target features seen in /proc/cpuinfo.

Yeah, that's the difference from X86. `UseSVE` is a vm flag which lets user to choose whether use the sve feature or not. And the sve cpu feature is still there that will not been influenced by the VM flag.

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PR: https://git.openjdk.org/jdk/pull/9623