[foreign-memaccess+abi] RFR: 8315096: Allowed access modes in memory segment should depend on layout alignment

[Paul Sandoz]

On Mon, 28 Aug 2023 17:23:02 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

> > I don't exactly recall why we restricted on 32-bit platforms, but it might have been because of some `Unsafe` restriction/complexity in supporting the atomicity that is required for volatile (or more generally non-plain) access (e.g., see https://shipilev.net/blog/2014/all-accesses-are-atomic/#_implementation_specifics). So we probably said well we won't support it at all, but i doubt we assert on that given 32-bit is not a system we generally focus on.
> 
> Note: I believe this text is really meant to mean: "these access modes are supported, but access is not atomic" (as in: might tear).
> 
> Which is caused by the slightly overloaded use of the letters `atomic` in the var handle javadoc.

Yes, i agree.. I will log an issue to update the text VarHandle text.

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PR Comment: https://git.openjdk.org/panama-foreign/pull/876#issuecomment-1696077997