RFR: 8287567: AArch64: Implement post-call NOPs

[Rickard Bäckman]

On Wed, 1 Jun 2022 02:01:02 GMT, Dean Long <dlong at openjdk.org> wrote:

> Is there any advantage to having the first instruction be "nop" instead of a branch that skips over the movks?
> 
> ```
> b done
> movk zr, lo
> movk zr, hi
> done:
> ```
> 
> I was going to suggest:
> 
> ```
>  b done
>  (raw data)
>  done:
> ```
> 
> but then it might be hard for NativePostCallNop::check() to prevent false positives.

The NOP is required for deoptimization.

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PR: https://git.openjdk.java.net/jdk/pull/8955