RFR: 8262096: Vector API fails to work due to VectorShape initialization exception [v7]

[Paul Sandoz]

On Tue, 2 Mar 2021 02:11:08 GMT, Jie Fu <jiefu at openjdk.org> wrote:

>> Hi all,
>> 
>> Vector API fails to work when:
>>  - case 1: MaxVectorSize is set to <=8, or
>>  - case 2: C2 is disabled
>> 
>> The reason is that {max/preferred} VectorShape initialization fails in both cases.
>> And the root cause is that VectorSupport_GetMaxLaneCount [1] returns unreasonable values (0 for case 1 and -1 for case 2).
>> 
>> Vector API should not depend on C2 to run.
>> It should work even there is no JIT compiler since it's a Java-level api.
>> So let's fix it.
>> 
>> Testing:
>>   - jdk/incubator/vector with -XX:MaxVectorSize=default/8 on Linux/x64
>> 
>> Thanks.
>> Best regards,
>> Jie
>> 
>> [1] https://github.com/openjdk/jdk/blob/master/src/hotspot/share/prims/vectorSupport.cpp#L364
>
> Jie Fu has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add VectorShape.getMaxVectorBitSize

Marked as reviewed by psandoz (Reviewer).

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PR: https://git.openjdk.java.net/jdk/pull/2722