RFR: 8255339: CodeBuffer::_last_insn is only used on AArch64

[Eric Liu]

On Thu, 7 Jan 2021 08:07:16 GMT, Eric Liu <github.com+10482586+theRealELiu at openjdk.org> wrote:

> CodeBuffer::_last_insn was used to merge consecutive memory barriers and
> adjacent load/store on AArch64.
> 
> This patch marks it as AArch64 only so that 8 bytes could be dropped
> from CodeBuffer on other architectures.

Can anyone help to take a look at this **trivial** PR?

-------------

PR: https://git.openjdk.java.net/jdk/pull/1971