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

[Fei Gao]

On Tue, 15 Feb 2022 06:48:10 GMT, Fei Gao <fgao at openjdk.org> wrote:

> Hi,
> 
> 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.
> 
> Thanks.

Hi @theRealAph , can I have your review :)? Thanks.

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