RFR: 8255243: Reinforce escape barrier interactions with ZGC conc stack processing

[Richard Reingruber]

On Fri, 23 Oct 2020 10:39:10 GMT, Erik Österlund <eosterlund at openjdk.org> wrote:

>> @reinrich Since you wrote the escape barrier, I thought I'd ping you in case you are interested. This makes the mechanism more robust and reliable, w.r.t. concurrent stack processing. No issue observed, but looks wrong with the new vector API deoptimization code that was integrated recently. This makes it more future-proof and easy to reason about.
>
> Forgot to mention, but I tested this from tier1-5, to sanity check that the new solution doesn't introduce any new issues.

@fisk thanks for pinging. I remember reading about a new vector API a while ago and noticed that it potentially interferes with escape barriers but then I lost track. I'll look at this.

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

PR: https://git.openjdk.java.net/jdk/pull/832