RFR: 8356760: VectorAPI: Optimize VectorMask.fromLong for all-true/all-false cases [v2]

[erifan]

On Fri, 27 Jun 2025 06:04:54 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

>> src/hotspot/share/opto/vectorIntrinsics.cpp line 80:
>> 
>>> 78:     return false;
>>> 79:   }
>>> 80:   long mask = (0xFFFFFFFFFFFFFFFFULL >> (64 - vlen));
>> 
>> The higher bits of long input should be cleared. So we should generate an unsigned right shift instead of the signed one?
>
> I noticed that you used `ULL` suffix. So it should be fine. Please ignore above comment. Thanks!

Yeah, thanks~

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PR Review Comment: https://git.openjdk.org/jdk/pull/25793#discussion_r2181359573