C1: Plain memory accesses are emitted with membars with +AlwaysAtomicAccesses

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    • Type: Enhancement
    • Resolution: Fixed
    • Priority: P4
    • 24
    • Affects Version/s: 17, 21, 23, 24
    • Component/s: hotspot
    • b25

      Noticed this while looking at current AlwaysAtomicAccesses uses. This flag is useful to experiment with Valhalla flattening and generically with long atomicity.

      See for example here: https://github.com/openjdk/jdk/blob/895a7b64f01dec7248549b127875edcf006457cf/src/hotspot/share/gc/shared/c1/barrierSetC1.cpp#L143 -- we set `is_volatile` when `+AlwaysAtomicAccesses`, so it emit barriers.

            Assignee:
            Xiaolong Peng
            Reporter:
            Aleksey Shipilev
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              Created:
              Updated:
              Resolved: