RFR: 8325821: [REDO] use "dmb.ishst+dmb.ishld" for release barrier [v2]

[Aleksey Shipilev]

On Thu, 23 May 2024 10:55:41 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Test is added as merge_dmb_all_kinds
>
> Right. I was implicitly thinking that we can do this without coding the explicit patterns into the test. As it stands now, it is hard to check that generated patterns are actually correct. Let me see if I can whip up a sample of what I had in mind.

I was thinking about this: [improve-tests.patch](https://github.com/openjdk/jdk/files/15419452/improve-tests.patch). Note how it uses the constants for better readability, and also runs the test in both `AlwaysMergeDMB` modes. You might want to adapt other tests to similar pattern.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19278#discussion_r1611958667