> Here's my question: It seems inevitable that people will eventually port all LLVM's smarts directly into MLIR, and remove the need to shift between the two. I

> Here's my question: It seems inevitable that people will eventually port all LLVM's smarts directly into MLIR, and remove the need to shift between the two. Is that right? Theoretically, yes -- taking years if not decades for sure. And set aside (middle-end) optimizations, I think people often forgot another big part of LLVM that is (much) more difficult to port: code generation. Again, it's not impossible to port the entire codegen pipeline, it just takes lots of time and you need to try really hard to justify the advantage of moving over to MLIR, which at least needs to show that codegen with MLIR brings X% of performance improvement.