RFR: 8288992: AArch64: CMN should be handled the same way as CMP

[Andrew Dinn]

On Wed, 22 Jun 2022 17:03:42 GMT, Andrew Haley <aph at openjdk.org> wrote:

> At present, `cmp(r8, -1)` fails at compile time, but `cmn(r8, -1)` fails at runtime. We should fix cmn() to be the same as `cmp()`. 
> 
> After this change, it's much less likely that we'll be surprised by immediate overflows in `cmn()`.

Looks good.

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Marked as reviewed by adinn (Reviewer).

PR: https://git.openjdk.org/jdk/pull/9246