The PR itself says: > The new Rust version of YJIT has reached parity with the C version, in that it passes all the CRuby tests, is able to run all of the YJIT

The PR itself says: > The new Rust version of YJIT has reached parity with the C version, in that it passes all the CRuby tests, is able to run all of the YJIT benchmarks, and performs similarly to the C version (because it works the same way and largely generates the same machine code). We've even incorporated some design improvements, such as a more fine-grained constant invalidation mechanism which we expect will make a big difference in Ruby on Rails applications.