RFR: 8280511: AArch64: Combine shift and negate to a single instruction [v2]

[Fei Gao]

On Thu, 31 Mar 2022 13:55:41 GMT, Nick Gasson <ngasson at openjdk.org> wrote:

>> Fei Gao has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:
>> 
>>  - Merge branch 'master' into fg8280511
>>    
>>    Change-Id: I80c9540ef3191d1d828b1d123ee346050152ac5b
>>  - 8280511: AArch64: Combine shift and negate to a single instruction
>>    
>>    In AArch64,
>>    
>>    asr     x10, x1, #31
>>    neg     x0, x10
>>    
>>    can be optimized to:
>>    
>>    neg    x0, x1, asr #31
>>    
>>    To implement the instruction combining, we add matching rules in
>>    the backend.
>>    
>>    Change-Id: Iaee06f7a03e97a7e092e13da75812f3722549c3b
>
> Looks OK to me too.

Thanks for your review @nick-arm :)

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PR: https://git.openjdk.java.net/jdk/pull/7471