xrcf

The xr compiler framework

Notes

Name

"There are only two hard things in Computer Science: cache invalidation and naming things."

The meaning of "xrcf" is xr compiler framework. What the x and r stand for is undefined. The r could be "rust", "rewrite", "recursive", or something else. The x could be anything.

LLVM's codebase

Let's not include any LLVM code like Zig is moving towards. LLVM is great, but it's also big. Including the C files would require lots of compilation. Calling out to an installed LLVM version is better but is hard with package versions and such. Let's for now just generate LLVM IR and let the client compile it themselves.

Operation

MLIR has a Op trait where each struct that implements it contains a Operation field. This means that Operation is very generic and the various Op implementations all access the real data through the Operation field.

A downside of the Operation field is that it may contain fields that are not necessary. For example, arith.constant does not take any operands, but the Operation field will still contain an empty operands field.

The benefit is that transformations do not require the fields to be copied. They can just call it a different type while pointing to the same Operation struct. This is probably why MLIR uses it. Otherwise, transforming all ops from one dialect to another would require copying all op fields.

But wait, it's not that much copying. Many fields are just pointers to other data. Instead focus on the fact that any Op transformation takes ownership of the data. Then, it's will be harder to mess up the underlying data. There will be less state to keep track of.

In summary: Do not prematurely optimize!