[flang-commits] [flang] [flang][rfc] Add represention of volatile references (PR #132486)

[Asher Mancinelli via flang-commits]

ashermancinelli wrote:

Thanks for the reviews, everyone!

In response to @kiranchandramohan and @jeanPerier 's questions/comments:
> What about array_merge_store?

> fir_CopyOp will also need this interface.

There are several ops (copy, array_merge, embox, ext_embox) and at least one more type (`fir.box`) that will need to be updated to handle volatility. I will update this PR with those changes. I don't intend to merge this all at once, but it will be nice to have the full change in one diff to agree on the design before I start sending smaller patches.

Also, Jean suggested on the discourse thread that the volatile argument should _not_ have a default:
> it is easier to control/make sure code is aware of VOLATILE aspect by adding a flag in the existing memory type and making it a mandatory (not optional) value in the type builder/ctor of that type. That way, people have to provide some VOLATILE parameter when construction new result types and think for a minute where this information should come from in their case.

I like this idea and will include it in the next revision. This will make the diff much larger, but I agree that this will make it harder for users of the type to forget to handle volatility.

https://github.com/llvm/llvm-project/pull/132486