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

[Jie Fu]

On Fri, 3 Jun 2022 03:46:18 GMT, Jie Fu <jiefu at openjdk.org> wrote:

>> We do run vectorization (superword, vectorization, VectorAPI) tests in our testing with:
>> `-XX:UseAVX=0 -XX:UseSSE=3` and `-XX:UseAVX=0 -XX:UseSSE=2`
>
>> We do run vectorization (superword, vectorization, VectorAPI) tests in our testing with: `-XX:UseAVX=0 -XX:UseSSE=3` and `-XX:UseAVX=0 -XX:UseSSE=2`
> 
> 
> `compiler/c2/irTests/TestVectorizeURShiftSubword.java` still passed with `-XX:UseAVX=0 -XX:UseSSE=3` and `-XX:UseAVX=0 -XX:UseSSE=2`.
> 
> Maybe the IR test framework wouldn't accept VM args like `-XX:UseAVX=? -XX:UseSSE=?`?

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.

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