We are in the final stages of a grand transformation on the Rust compiler internals. Over the past year or so, we have been steadily working on a plan to change our internal compiler pipeline, as shown here: That is, we are introducing a new intermediate representation (IR) of your program that we call MIR: MIR stands for mid-level IR, because the MIR comes between the existing HIR ("high-level IR
![Introducing MIR](https://cdn-ak-scissors.b.st-hatena.com/image/square/cc73843c221f67fc442877f4f77a487e6f19c548/height=288;version=1;width=512/https%3A%2F%2Fwww.rust-lang.org%2Fstatic%2Fimages%2Frust-social-wide.jpg)