RFR: 8324734: Relax too-strict assert(VM_Version::supports_evex()) in Assembler::locate_operand() [v2]

[Vladimir Kozlov]

On Mon, 29 Jan 2024 09:30:02 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

>> Details see bug report. The gist is that HotSpot downgrades to UseAVX=2 on some processors, and reports supports_evex() == false, but the instruction decoder can still encounter EVEX instructions when (e.g.) hitting a SIGBUS in memset() - which does have EVEX instructions.
>> 
>> Testing:
>>  - [x] runtime/Unsafe/InternalErrorTest.java
>>  - [x] tier1
>
> Roman Kennke has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Distinguish between CPU and HotSpot features for supports_evex()

Good. I will submit our testing before approval.
And this needs second review.

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PR Review: https://git.openjdk.org/jdk/pull/17590#pullrequestreview-1849438969