RFR: 8292338: aarch64: Use cbnz instruction in gen_continuation_enter when possible

[Fei Yang]

On Mon, 15 Aug 2022 01:52:35 GMT, Fei Yang <fyang at openjdk.org> wrote:

> This is a trivial improvement for gen_continuation_enter on AArch64.
> On AAch64, we can combine Compare and Branch on Zero/Nonzero into CBZ/CBNZ to save one instruction.
> Tier1 tested with fastdebug build on aarch64-linux-gnu.

Thanks all for the quick review.

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PR: https://git.openjdk.org/jdk/pull/9872