RFR: 8283307: Vectorize unsigned shift right on signed subword types [v3]

[Jie Fu]

On Sat, 4 Jun 2022 01:02:30 GMT, Jie Fu <jiefu at openjdk.org> wrote:

>>> Two questions @fg1417 :
>>> 
>>> 1. Is `RShiftVB` generated with `-XX:UseAVX=0 -XX:UseSSE=2` on x86?
>>> 2. If the answer is no for question 1, why `TestVectorizeURShiftSubword.java` get passed?
>>>    Thanks.
>> 
>> @DamonFool , no `RShiftB` nodes are generated with `-XX:UseAVX=0 -XX:UseSSE=2` on x86. The test passed because when adding VM options `-XX:UseAVX=0 -XX:UseSSE=2` externally, the IR framework won't do the IR check and just run the java code, I verified and made the guess. But I'm not clear whether all external VM options would stop the IR framework to do the IR check.
>
>> As @fg1417 pointed, IR framework will not do any IR verification testing (it does not run test) when some flags are passed to test and not whitelisted (`UseAVX` and `UseSSE` are not on list):
>> https://github.com/openjdk/jdk/blob/master/test/hotspot/jtreg/compiler/lib/ir_framework/TestFramework.java#L105
> 
> Ah, I see.
> Thanks @vnkozlov for your explanation.

> > I don't see these changes passed pre-submit GitHub testing. Make sure they passed.
> 
> I don't know why the pre-submit GitHub testing didn't run in this PR. So I create a draft PR for this patch to run the pre-submit testing: #9026 .

The pre-submit testing finished without regression. @vnkozlov @fg1417 
Thanks.

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

PR: https://git.openjdk.java.net/jdk/pull/7979