I think they had a good dive here
https://www.youtube.com/watch?v=SEwTjZvy8vw
The gist is that MLIR (unlike LLVM) was designed to be multithreaded so the whole stack above LLVM IR is parallel, and then LLVM is used as a per-function codegen tool in parallel, so although LLVM itself is single threaded there are multiple seperate contexts of it. also I think they wrote their own linker.
That is hardly novel, here is the thesis for the Oberon multithreaded compiler from 2003.
https://www.research-collection.ethz.ch/entities/publication...
C# compiler is also fully multithreaded since the Roslyn rewrite in 2016.
The novelty is in parrelizing LLVM, which is traditionally a single-thread code generator.
So basically LLVM catching up with times.
Well, LLVM itself is still single-threaded; they just designed Mojo's compiler in such a way that the code generation part can be parallelised, which is something you can do if you understand LLVM from top to bottom. As far as I can see, no other production-grade LLVM consumer has been able to make it parallel; the single-threaded nature remains a major performance bottleneck.
loading story #49272226