[llvm] [flang] [compiler-rt] [clang-tools-extra] [mlir] [clang] [mlir][tosa] Add dialect version. (PR #79514)

[Jacques Pienaar via cfe-commits]

jpienaar wrote:

> This lack some information to me:
> 
> * What is the purpose of this?

To be able to flag incompatible bytecode files rather than have it fail later in mysterious ways. E.g., allows for a more strict failure.

> * What kind of compatibility is this supposed to provide?

None today. Aspirational to use to avoid making cross repo changes in more atomic manner.

> * What is the versioning scheme?

Version is just a single number but this doesn't mean this is versioned in any deep way vs being able to flag incompatible versions (some small update hooks such as for things like where i64 attribute is changed to i8 etc could be utilized, no promises yet on these existing for any extent of time). Main goal is really to reduce cross repo sync changes without initially any additional expectations.

Currently there aren't even any tests to flag if a version bump is needed. That would be nice, but no policy there yet.

https://github.com/llvm/llvm-project/pull/79514