RFR: 8372285: G1: Micro-optimize x86 barrier code [v3]

[Aleksey Shipilev]

On Fri, 21 Nov 2025 10:03:16 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Okay, thanks for the information, I am good with that. Although I think it would not hurt to make it explicit that we cared.
>
> Right, we can make some of these backward branches explicitly short, just to drive the point home. Done in new commit, let's see if testing complains about any new shortenings.

tier1 passes, running more tests now.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/28446#discussion_r2549343272