[llvm-dev] Various Intermediate Representations. IR

[James Courtier-Dutton via llvm-dev]

On Wed, 15 Apr 2020 at 17:28, David Blaikie <dblaikie at gmail.com> wrote:
>
> opaque pointers don't exist in the IR yet - the goal is to reduce the places that use non-opacity of pointer types already/today and then opacify the existing pointer type, rather than introducing an opaque pointer type & having it concurrently with non-opaque pointer types. (though in retrospect such a migration might've been worth considering and/or might still be used as part of the migration, I guess)
>

I would have thought that it would have been useful to have both
pointer types available.
For example, if one wished to move from an opaque pointer to MLIR, one
would need to add passes to derive types first.
So, having a pass that converts from opaque pointer to typed pointer
and back again would have been useful.
The approach you describe kind of reduces the flexibility of LLVM.
I think LLVM IR -> MLIR and MLIR -> LLVM IR  round tripping is a useful goal.

Kind Regards

James